Dark Matter 2025: From the Smallest to the Largest Scale

Jun 2, 2025, 11:00 AM → Jun 6, 2025, 6:00 PM Europe/Madrid

Santander, Spain

Bradley Kavanagh

06/06/2025: Dark Matter 2025 has now concluded. Many thanks to the organisers and participants. All the talk slides can be found here. 

Conference photos here: Monday, Wednesday.

Dark Matter 2025: From the Smallest to the Largest Scales is a conference devoted to discussing the latest developments in the field of dark matter, from experiments to theory and phenomenology. Alongside a small number of invited talks, the main focus will be on contributed talks and posters from members of the community. 

The conference will take place on 2 - 6 June 2025 in the city of Santander, a well known Summer resort on the northern coast of Spain, at the Gran Hotel Victoria. The conference will start in the afternoon on 2 June and will close at the end of the morning on 6 June.

Confirmed speakers:

• Rebekka Coles-Bieri (University of Zurich)⁠⁠
• Babette Döbrich (MPI, Munich)
• James Frost (University of Oxford)
• Vera Gluscevic (USC)
• Gudrid Moortgat-Pick (DESY, Hamburg)
• Roberto Ruiz de Austri (IFIC, Valencia)
• Tim Tait (UC Irvine)
• Pedro de la Torre Luque (IFT/UAM, Madrid) 

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The contributions from the previous meetings can be found here: Dark Matter 2016, Dark Matter 2018, Dark Matter 2021 (virtual), Dark Matter 2023. 

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DarkMatter2025-Logo.png

DarkMatter2025_posterDesign.pdf

Santander_guide_June2025.pdf

Mon, June 2

1 Registration + Coffee

2 Introduction (Addresses from IFCA, UC and LOC Chair)

OpeningRemarks_DM2025.pdf

Monday Afternoon I

3 Probing dark matter with strong lensing and the line of sight

Gravitational lensing is a powerful tool for constraining the nature and distribution of dark matter. Strong lensing observations allow comparisons between the mass and light profiles of galaxies, and dark matter subhalos have been detected through their perturbations to lensed images. Weak lensing probes the matter power spectrum, and thus the abundance and behaviour of dark matter, as well as placing constraints on new dark matter couplings.

Matter along the line of sight in strong lens systems complicates the comparison of the mass and light profiles of galaxies. However, it also leaves a potentially measurable imprint on strong lens images. In the last decade, strong lensing has been proposed as a novel probe of cosmic shear, and thus the matter power spectrum. I will present the current status of this work: the interpretation of the line-of-sight shear, the reasons to believe this signal can be reliably measured with current and upcoming survey telescopes, the lens modelling challenges which remain as obstacles, and the anticipated power of this technique in improving dark matter constraints.

Speaker: Daniel Johnson (CNRS/University of Montpellier)

Santander talk - Dark Matter and strong lensing.pdf

Santander talk - Dark Matter and strong lensing.pptx

4 Dark matter from extremely lensed stars at cosmological distances

Background stars at cosmological distances that appear near the critical curves of galaxy clusters can be magnified by extreme factors of O(1000) and be detectable in deep observations with the Hubble or James Webb space telescopes. The stellar nature of this objects can be confirmed thanks to microlensing by stars in the galaxy cluster that can temporarily boost the flux of the lensed star by a factor of a few. Larger and more luminous objects, such as small star forming regions or globular clusters are virtually immune to microlensing so when microlensing is observed, it indirectly confirms the background object is as small as an individual star. The magnification experienced by these stars is also very sensitive to the presence of dark matter substructures. I will review a few examples where lensed stars have been used to set tight constraints on certain models of dark matter and discuss the prospects to get even tighter constraints from future observations.

Speaker: Jose Maria Diego Rodriguez (IFCA)

Santander_DM2025_Kaiju.pdf

5 Phasing-in dark matter

Despite being an elegant mechanism to explain Dark Matter (DM) production, freeze-in introduces challenges: If DM interacts via non-renormalizable operators, the predictions are highly sensitive to the initial conditions, such as the reheating temperature of the universe. These issues are particularly relevant in models in which the universe deviates from radiation domination and the entropy of the Standard Model (SM) thermal bath is not conserved. In this talk, I will present a general freeze-in scenario in which a scalar field dominates the energy density of the universe before undergoing a first-order phase transition and then slowly decaying to visible particles. The decays lead to a second phase of reheating of the radiation bath and to additional contributions to DM freeze-in. I will explore the conditions under which these late contributions dominate over the initial DM abundance produced at primordial reheating. In this scenario, referred to as phase-in, the final abundance of DM is primarily determined by the details of the phase transition and subsequent reheating, and insensitive to the details of inflationary reheating.

Speaker: Henda Mansour (KIT)

DM Phase-in.pdf

6 Towards realistic SIMP dark matter

The so-called "strongly interacting massive particles" (SIMPs) refer to a class of dark matter candidates with the relic abundance set by the 3$\to$2 interactions which allows for dark matter with sub-GeV masses, not yet strongly constrained by direct detection experiments. Interestingly, SIMP dark matter features relatively strong self-interactions that may explain the small-scale structure puzzles. We investigate the realisation of SIMP models where dark pions form dark matter, protected from decay by dark flavour symmetries. We observe that the relic abundance of the dark pions depends sensitively on the masses of heavier states present in dark QCD-like scenarios such as dark vector mesons. We improve on existing results by using recent lattice simulations connecting the masses of dark pions and vector mesons. Furthermore, a portal between dark and visible sectors is usually assumed to maintain thermal equilibrium. To obtain fully realistic results, we explicitly add the dark photon portal and study its effect on dark matter relic abundance and stability.

Speaker: Halvor Melkild (University of Oslo)

dm25_melkild.pdf

7 Cogenesis by QCD axion

We show how cogenesis of dark matter and baryon asymnmetry can arise from kinetic misalignment of the QCD axion. For this, we work out the DFSZ and KSVZ axion models associated with the type-I seesaw mechanism and the PQ inflacion.

Speaker: EUNG JIN CHUN (Korea Institute for Advanced Study)

2506 Santander Cogenesis.pdf

8 Testing the dark origin of neutrino masses with oscillation experiments

The origin of neutrino masses remains unknown to date. One popular idea involves interactions between neutrinos and ultralight dark matter, described as fields or particles with masses $m_\phi \lesssim 10\,\mathrm{eV}$. Due to the large phase-space number density, this type of dark matter exists in coherent states and can be effectively described by an oscillating classical field. As a result, neutrino mass-squared differences undergo field-induced interference in spacetime, potentially generating detectable effects in oscillation experiments. By analyzing data from the Kamioka Liquid Scintillator Antineutrino Detector (KamLAND), a benchmark long-baseline reactor experiment, we show that the hypothesis of a dark origin for the neutrino masses is disfavored for $m_\phi \lesssim 10^{-14}\,\mathrm{eV}$, compared to the case of constant mass values in vacuum. The mass range $10^{-17}\,\mathrm{eV} \lesssim m_\phi \lesssim 10^{-14}\,\mathrm{eV}$ can be further tested in current and future oscillation experiments by searching for time variations (rather than periodicity) in oscillation parameters. Furthermore, we demonstrate that if $m_\phi\gg 10^{-14}\,\mathrm{eV}$, the mechanism becomes sensitive to dark matter density fluctuations, which suppresses the oscillatory behavior of flavor-changing probabilities as a function of neutrino propagation distance in a model-independent way, thereby ruling out this regime.

Speaker: Hong-Yi Zhang (Tsung-Dao Lee Institute)

nu_mass

4:30 PM Coffee Break

Monday Afternoon II

9 Constraining Flavored Dark Matter: A Systematic Study in the DMFV Framework

The null results of dark matter searches targeting weakly interacting massive particles (WIMPs) put increasing pressure on the simplest realizations of WIMP models. In response, we explore an extended dark sector with a non-trivial flavor structure within the Dark Minimal Flavor Violation (DMFV) framework. These models extend the standard dark matter paradigm by introducing flavor-dependent interactions between dark matter and the Standard Model. Flavored dark matter models offer a rich phenomenology, linking dark matter properties to the flavor structure of the visible sector, which leads to distinctive signatures in cosmology, direct detection, flavor observables, and collider experiments. We therefore develop a framework to perform an automated systematic study of the phenomenology of different DMFV models. Using this framework, we analyze the viable parameter space of a specific flavored dark matter model and identify which constraints have a significant impact on the parameter space. Furthermore, we discuss new potential opportunities for searches for the model at colliders.

Speaker: Lena Rathmann (RWTH Aachen University)

DM2025_Rathmann.pdf

10 Unlocking the Inelastic Dark Matter Window with Vector Mediators

Despite the robust cosmological and astrophysical evidence confirming the existence of a non-baryonic matter component in the Universe, the underlying nature of Dark Matter (DM) remains a mystery. Among the several possible scenarios, light DM candidates thermally produced in the early Universe are especially interesting, since their abundance could be set via the standard freeze-out mechanism. Additionally, new light states can present a rich phenomenology and are attracting increasing attention due to recent experimental capabilities to probe dark sectors with feeble interactions. In particular, inelastic DM (iDM) candidates are an appealing option, since they can avoid cosmic microwave background (CMB) radiation bounds as well as indirect and direct detection searches. Although such models have been intensively studied in the literature, the usual scenario is to consider a secluded dark photon mediator. In this work, we consider the case of iDM with general vector mediators and explore the consequences of such a choice in the relic density computation, as well as for the cosmological and experimental bounds. We examine models with couplings to baryon and lepton number and show new viable parameter regions for inelastic dark matter models. Especially, anomaly-free gauge groups with non-universal couplings to leptons open new windows of the parameter space for thermal dark matter yet unexplored by experiments. We also provide a numerical Python library to compute the relic densities for user-defined gauge charges.

Speaker: Ana Luisa Foguel (University of São Paulo)

general_mediators_iDM_DM2025_pdf.pdf

11 Resonant or asymmetric: The status of sub-GeV dark matter

Sub-GeV dark matter (DM) has been gaining significant interest in recent years, since it can account for the thermal relic abundance while evading nuclear recoil direct detection constraints. However, sub-GeV DM is still subject to a number of constraints from laboratory experiments, and from astrophysical and cosmological observations. In this work, we compare these observations with the predictions of two sub-GeV DM models (Dirac fermion and scalar DM) within frequentist and Bayesian global analyses using the Global And Modular BSM Inference Tool (GAMBIT). We infer the regions in parameter space preferred by current data, and compare with projections of near-future experiments, providing a status update to sub-GeV DM.

Speaker: Taylor Gray (Chalmers University of Technology)

DM_TaylorGray.pdf

12 Dark matter as bound states in asymptotically safe quantum gravity.

Many dark matter models become unviable when embedded into the framework of asymptotically safe quantum gravity. In this work, we investigate dark matter arising as bound states of fundamental fermions in the strongly-coupled regime of a gauge theory. Modeling the self-interactions of dark baryons via the effective-range approach, we perform a multi-scale analysis in which we combine phenomenological constraints with the theoretical requirements imposed by consistent embedding into asymptotically safe quantum gravity. We find a regime in parameter space that is compatible with all constraints, indicating that this theory may account for dark matter while being ultraviolet complete and predictive. Additionally, we discover a generic feature: kinetic mixing between visible and dark photons is dynamically driven towards tiny values within the ultraviolet complete setting; a crucial condition to prevent an overabundance of dark matter produced via the kinetic mixing portal in the freeze-in mechanism.

Speaker: Abhishek Chikkaballi (National Centre for Nuclear Research, Warsaw)

Chikkaballi_DM_2025.pdf

13 Listening for ultra-heavy dark matter with underwater acoustic detectors

Ultra-heavy dark matter is a class of candidates for which direct detection experiments are ineffective due to the suppressed dark matter flux. We explore the potential of large underwater acoustic arrays, developed for ultra-high energy neutrino detection, to detect ultra-heavy dark matter. As ultra-heavy dark matter traverses seawater, it deposits energy through nuclear scattering, generating thermo-acoustic waves detectable by hydrophones. We derive the dark matter-induced acoustic pressure wave from first principles and characterise attenuation effects, including frequency-dependent modifications due to viscous and chemical relaxation effects in seawater, providing an improved framework for signal modelling. Our sensitivity analysis for a hypothetical 100 cubic kilometre hydrophone array in the Mediterranean Sea shows that such an array could probe unexplored regions of parameter space for ultra-heavy dark matter, with sensitivity to both spin-independent and spin-dependent interactions. Our results establish acoustic detection as a promising dark matter search method, paving the way for analysing existing hydrophone data and guiding future detector designs.

Speaker: Damon Cleaver (damon.cleaver@kcl.ac.uk)

DM2025_DamonCleaver.pdf

14 Interactions of boosted dark matter with nuclei and implications for DUNE

Halo dark matter particles with sub-GeV masses do not have sufficient kinetic energy to induce detectable recoils of heavy nuclei in the detectors, direct detection experiments, hence, loose sensitivity to such light dark matter. Dark matter particles can be, however, accelerated by different mechanisms and even light dark matter can then provide observable signatures. These signatures include not only coherent dark matter-nucleus scattering, but also scattering off individual nucleons or deep inelastic scattering. The latter processes can be detected by neutrino experiments and we demonstrate their importance on the example of dark matter boosted by scattering with galactic cosmic rays that might be observed by the DUNE experiment.

Speaker: Helena Kolesova (University of Stavanger)

Santander_Kolesova.pdf

7:30 PM Welcome Reception

Tue, June 3

Tuesday Morning I

15 An Overview of Direct Detection

Direct detection experiments aim to shed light on the thus far elusive nature of dark matter through measuring its potential interactions with ordinary matter. This talk will provide an overview of these experiments and the status of the field. After briefly summarising the possible dark matter candidates, I will cover some of the detection strategies and recent results, before discussing the prospects for upcoming projects that will lead to future, more sensitive searches.

Speaker: Dr Amy Cottle (University College London)

DarkMatter_Santander_Cottle.pdf

16 Latest results from the LUX-ZEPLIN (LZ) Experiment

The LUX-ZEPLIN (LZ) experiment is located at the Sanford Underground Research Facility in Lead, South Dakota. LZ is primarily designed to detect interactions of dark matter in the form of weakly-interacting massive particles (WIMPs) using a 7 tonne dual-phase xenon time projection chamber (TPC). LZ has been acquiring science data since 2021 under stable operating conditions. Now, with a combined exposure of 4.2 tonne-years from all science campaigns, LZ has placed the most stringent limits on spin-independent WIMP-nucleon cross section down to $2.2 \times 10^{-48}$ cm$^2$ for a 43 GeV/c$^2$ WIMP mass. In this talk I'll present the current status of the LZ experiment and its latest dark matter search results.

Speaker: Paulo Brás (LIP)

Latest_results_from_the_LUX-ZEPLIN_(LZ)_Experiment-DM2025_v2.pdf

17 WIMP and Neutrino Direct Detection with XENONnT

Direct detection experiments look for scattering events of dark matter with known Standard Model particles. Scattering on heavy nuclei is a promising approach to searching for heavy (above a few GeV) dark matter candidates. Liquid noble elements, like xenon, are especially suited because of their inert behavior, ability to be purified and be low in radioactivity.
XENONnT is the result of two decades of detector development for direct dark matter searches by the XENON collaboration. Starting in 2020 with a total xenon mass of 8.6 tons, the experiment is still collecting and analyzing data.
The collaboration has set some of the most stringent limits on dark matter interactions with nuclei and has measured coherent elastic neutrino-nucleus scattering (CEvNS) with solar neutrinos, pushing into the "neutrino fog." This measurement demonstrates XENONnT’s capabilities not just as a dark matter detector, but also as a powerful tool for rare-event searches, including neutrino physics, double beta decay, and axion searches. In this talk, the newest results are presented.

Speaker: Kai Böse (Max-Planck-Institut für Kernphysik)

Boese_WIMP_and_Neutrino_Direct_Detection_with_XENONnT.pdf

18 Direct detection of dark matter at the CRESST III experiment

Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) is a direct dark matter (DM) detection experiment located in the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The experiment operates scintillating crystals at cryogenic temperatures to search for nuclear recoils from DM particles and has achieved a threshold of $\sim$10 eV in its third phase (CRESST III). The sensitivity to measure small energy depositions makes CRESST one of the leading experiments in sub-GeV DM searches. A major challenge for all direct low-mass DM searches with solid state detectors is the presence of an unknown event population at very low energies, called the low energy excesses (LEE). The scientific effort at CRESST in the latest run has been primarily towards the understanding of the origin of this excess.
This talk will provide an overview of CRESST, highlighting the latest results from the experiment, and the plans for the future.

Speaker: Samir Banik

DM2025_Santander_SB.pdf

11:35 AM Coffee Break

Tuesday Morning II

19 DAMIC-M status and latest results

The DAMIC-M (DArk Matter In CCDs at Modane) experiment will use Skipper CCDs to search for low-mass (sub-GeV) dark matter underground at the Laboratoire Souterrain de Modane (LSM). With approximately 0.7 kg of silicon target mass and sub-electron energy resolution, the detector will exceed both the exposure and energy threshold (eV scale) of previous experiments. These capabilities will grant DAMIC-M world-leading sensitivity to a variety of hidden-sector dark matter candidates. In this talk, we will present science results from a prototype detector, assess the performance of CCD modules, and provide an update on the detector construction at LSM.

Speaker: Carlos Centeno (IFCA (UC-CSIC))

CarlosCenteno_2025DMtalk.pdf

20 Searching for sub-GeV particle dark matter with Spherical Proportional Counters

The NEWS-G collaboration is searching for light dark matter using spherical proportional counters [1]. Access to 50 MeV to 10 GeV mass range is enabled by the combination of single electron threshold, light gaseous targets (H, He, Ne), and highly radio-pure detector construction. Most recently, new constraints on spin-dependent
interactions of dark matter with protons were obtained [2] with the commissioning data of a 140 cm in diameter spherical proportional counter, S140, constructed at LSM using 4N copper with 500 μm electroplated inner layer [3]. The detector currently operates in SNOLAB, with the first physics data-taking campaign recently completed. The latest physics results will be presented along with the recent developments on the detector instrumentation, namely individual read-out of the multi-anode sensor and electroformation techniques. The path towards DarkSPHERE, a large-scale spherical proportional counter fully electroformed underground at the Boulby Underground Laboratory will be discussed [4].

[1] https://arxiv.org/abs/2502.11870
[2] https://arxiv.org/abs/2407.12769
[3] https://arxiv.org/abs/2008.03153
[4] https://arxiv.org/abs/2301.05183

Speaker: Konstantinos Nikolopoulos (University of Hamburg/University of Birmingham)

20250603_kn_DM25.pdf

21 BULLKID-DM: searching for light WIMP with monolithic arrays of silicon detectors

BULLKID-DM is a new experiment aimed at searching for hypothetical
WIMP-like Dark-Matter particles with mass around 1 GeV or below and
cross-section with nucleons smaller than $10^{-41}$ cm$^{2}$. The
target detector consists of a stack of diced silicon phonon collectors,
acting as an array of particle absorbers sensed by multiplexed Kinetic
Inductance Detectors (KIDs). The target will amount to 800 g subdivided
in more than 2000 silicon dice. The aim is to control the backgrounds
by creating a fully active structure and by applying fiducialization
techniques.

Following the encouraging results from a 20 g prototype detector,
here we present the first operation of 3-wafer demonstrator array
(for a total of 60 g and 180 silicon dice), operated on surface with
a mild shield. The recorded background is here compared with Geant4
simulations conducted by the collaboration.

Finally, we present the plan for the deployment of the experiment
at the shielded underground site of Gran Sasso laboratories in Italy.
The commissioning will happen in two stages: first, the demonstrator
array will be deployed at the beginning of 2026 in the cryo-platform.
Once the success of the demonstrator stage is ensured and the setup
is fully characterized, the full experimental setup will follow and
is expected to be commissioned at Gran Sasso in the beginning of 2027.

Speaker: Angelo Cruciani (INFN Sezione Di Roma)

BULLKID-DM DM2025.pdf

22 Dark Matter Particle Flux in a Dynamically Self-consistent Milky Way Model

We present a dynamically self-consistent model of the Milky Way constrained by Gaia observations, which includes a radially anisotropic dark matter (DM) halo component. The component is the result of a galaxy merger and affects the DM velocity distribution functions, which in turn affects the measured DM flux in both heliocentric and geocentric reference frames. Comparing our model with previous ones, we observe a modest but significant effect on the derived DM detection rates. In particular, direction-sensitive detectors would observe a unique kinematic signature caused by the non-Gaussian component.
Our results underline the importance of taking into account the dynamics of our galaxy in the construction of the dark matter model and its effect on potential detections in the future.

Speaker: Lucijana Stanic (University of Zurich)

DMflux_Stanic

23 Axion Search with RADES

The RADES (Relic Axion Detection Exploratory Setup) team originated in 2016 for the search of dark matter axions with haloscopes. Recently, the RADES collaboration has produced their most sensitive physics results for axion masses around 36.56 µeV. This team has made further research advances in topics such as the design of cylindrical (for operation at the MPP Bluefors system) and quasi-cylindrical (to be installed at the BabyIAXO magnet) cavities with mechanical tuning systems (for frequencies of the order of 8.2-9 GHz and 300 MHz, respectively), the use of high temperature superconducting coatings, or the implementation of quantum technologies for the improvement of haloscopes (quantum-limited detection) employing Superconducting QuBits (transmons). This talk gives a brief overview of these recent developments in the collaboration.

Speaker: Dr Jose María García Barceló (Max Planck Institut für Physik)

Poster_DM2025_JMGB.pdf

Slides_JMGB.pdf

Slides_JMGB.pptx

1:30 PM Lunch

Tuesday Afternoon I

24 Galaxy Simulations and what they can tell us about Dark Matter

Galaxy simulations provide a powerful framework for testing dark matter models by linking theoretical predictions to observable structures across cosmic scales. By studying the formation and evolution of galaxies in different dark matter scenarios, simulations help identify signatures that could distinguish between cold dark matter and alternative models. Low surface brightness features, such as stellar streams and diffuse halos, are particularly promising probes since their structure and persistence are sensitive to the gravitational potential they evolve in. Dwarf galaxies, with their shallow potentials and high dark matter fractions, offer additional constraints, as their formation and abundance depend on the fundamental properties of dark matter. However, the complex interplay of baryonic processes complicates this picture, making it essential to disentangle their effects from those of dark matter. I will highlight recent advances in high-resolution cosmological and idealized simulations that aim to address this challenge, including efforts within the ARRAKIHS mission to leverage detailed observations of Milky Way analogs. These combined approaches are key to refining our understanding of dark matter’s role in shaping galaxies and the large-scale universe.

Speaker: Rebekka Bieri (University of Zurich)

DMSantander_Simulations_ARRAKIHS_Bieri.pdf

25 Constraining WDM Particle Mass with Dwarf Galaxies Using DREAMS Simulations

The small-scale distribution of dark matter (DM) remains a key challenge in modern cosmology. While the ΛCDM paradigm successfully describes large-scale structure formation, tensions persist at galactic and sub-galactic scales, particularly in the abundance and internal structure of dwarf galaxies. Warm dark matter (WDM) has emerged as a compelling alternative to cold dark matter (CDM), as its suppressed small-scale power spectrum modifies the formation and evolution of low-mass galaxies.
In my talk, I will discuss, using high-resolution hydrodynamical simulations from the DREAMS project (DaRk mattEr with AI and siMulationS), a procedure to constrain the mass of WDM particles, by examining its impact on galactic scaling relations and number density of low-mass galaxies.
I will show that the number of galaxies with stellar masses M_{*} ≲ 10^{8}M_{☉} is sensitive to the WDM particle mass. As the WDM mass decreases, the number of dwarf galaxies predicted in simulations drops. This effect emerges clearly in Milky Way zoom-in simulations, where the higher resolution allows us to probe lower-mass galaxies.
By comparing simulated scaling relations —such as size, dark matter content, dark matter fraction, and total mass versus stellar mass in galaxies—with observational datasets, such as SPARC and Local Volume dwarf galaxies, I will assess degeneracies between WDM effects and baryonic feedback. Using a statistical approach based on χ² minimization, I will demonstrate how the WDM particle mass influences both the number and structural properties of dwarf galaxies.
Looking ahead, the vast number of dwarf galaxies discovered in wide-field surveys, such as the Euclid Wide Survey, will strengthen the statistical power needed to test these predictions.

Speaker: Michela Silvestrini (INAF, Osservatorio Astronomico di Capodimonte-Università di Napoli, Federico II)

SILVESTRINIMichela_DM2025.pdf

26 A detailed characterization of low-mass dark matter subhalo tidal tracks via numerical simulations

A number of studies assert that dark matter (DM) subhaloes without a baryonic counterpart and with an inner cusp always survive no matter the strength of the tidal force they undergo.
In this work, we perform a suite of numerical simulations specifically designed to analyse the evolution of the circular velocity peaks ($V_\mathrm{max}$, and its radial value $r_\mathrm{max}$) of low-mass DM subhaloes due to tidal stripping. To perform this task, we have employed the improved version of the DASH library, introduced in our previous work Aguirre-Santaella et al. (2023) to study subhalo survival.
More specifically, we follow the tidal evolution of a single DM subhalo orbiting a Milky Way (MW)-size halo, the latter with a baryonic disc and a bulge replicating the actual mass distribution of the MW. We simulate subhaloes with unprecedented accuracy, varying their initial mass, concentration, orbital parameters and inner slope (NFW and prompt cusps are considered). We also consider the effect of the time-evolving gravitational potential of the MW itself.
Here, we also broaden our vision with respect to previous literature not just characterizing tidal tracks at the apocentres, but exploring the pericentres as well. Several important discrepancies arise, especially with respect to works that do not account for baryonic material inside the host.
For our fiducial setting, we find $V_\mathrm{max}$ to change approximately the same after each orbital period, whilst $r_\mathrm{max}$ decreases less drastically for later orbits. This implies a larger increase in velocity concentrations for the first orbit compared to subsequent ones.
In general, $r_\mathrm{max}$ shrinks more than $V_\mathrm{max}$, leading to a continuous rise of subhalo concentration with time. The velocity concentration at present is found to be up to two orders of magnitude higher than the one at infall.
These findings significantly enhance our understanding of the dynamics and properties of low-mass DM subhaloes, providing valuable insights for future research, simulations and observations, as well as for indirect searches of DM.

Speaker: Alejandra Aguirre-Santaella (Institute for Computational Cosmology, Durham University (ICC Durham))

AAguirreSantaella-ttracks.pptx

27 Diverse dark matter haloes in Two-field Fuzzy Dark Matter

Fuzzy dark matter (FDM) is a compelling candidate for dark matter, offering a natural explanation for the structure of diffuse low-mass haloes. However, the canonical FDM model with a mass of $10^{-22}~{\rm eV}$ encounters challenges in reproducing the observed diversity of dwarf galaxies, except for possibly scenarios where strong galactic feedback is invoked. The introduction of multiple-field FDM can provide a potential resolution to this diversity issue. The theoretical plausibility of this dark matter model is also enhanced by the fact that multiple axion species with logarithmically-distributed mass spectrum exist as a generic prediction of string theory. In this talk, I consider the axiverse hypothesis and investigate non-linear structure formation in the two-field fuzzy dark matter (2FDM) model.

Speaker: Hoang Nhan Luu (Donostia International Physics Center)

DM2025_HNL.pdf

4:35 PM Coffee Break + Poster Session

Tuesday Afternoon II

28 Deep Learning in the Search for Dark Matter: An Overview

Deep learning has quickly become a valuable tool in the quest to understand dark matter, helping researchers explore faint signals across a range of experiments—from high-energy colliders to direct and indirect searches. By sifting through vast datasets and uncovering subtle patterns, these techniques can reveal signs of dark matter that traditional approaches might miss. This talk provides a broad overview of how deep learning and related machine learning methods are reshaping our search for dark matter, with an emphasis on key breakthroughs and ongoing challenges. We will also look ahead to promising future directions.

Speaker: Roberto Ruiz de Austri (IFIC, Valencia)

DM_AI_rruiz.pdf

29 Leveraging Machine Learning to Detect Dark Matter Subhalos in the Milky Way

Detecting dark (matter) subhalos on sub-galactic scales could offer critical insights into the nature of DM, given the limited observational constraints on the low-mass end of the subhalo mass function. In this talk, we will explore a novel method for finding dark subhalos by detecting stellar wakes —perturbations in the positions and velocities of stars caused by interactions with orbiting dark subhalos. We will discuss the feasibility of using supervised and unsupervised Machine Learning techniques to detect these stellar wakes, given the tremendous increase in high-precision data from current and future astronomical surveys.

Speaker: María Benito (Tartu observatory, University of Tartu)

2025_DM2025_Santander_indico.pptx

30 The Dark Matter distribution in the Milky Way and external galaxies

In the first part of this talk, I will discuss the impact of Gaia data on determining the dark matter distribution of our host galaxy, the Milky Way, presenting state-of-the-art results based on the latest data within a framework that has been tested over the past decade.

In the second part, I will introduce a recently developed machine learning method designed to infer the dark matter distribution in external galaxies. I will highlight how algorithms trained on synthetic galaxies within cosmological simulations can achieve a high level of accuracy, potentially providing a viable alternative to the traditional Rotation Curve method.

Speaker: Fabio Iocco (Università di Napoli "Federico II")

iocco-Santander-draft1.pdf

31 Dark matter minihalos from primordial magnetic fields

Primordial magnetic fields (PMFs) offer a simple explanation for the origin of galactic magnetic fields as well as of the purportedly detected magnetic fields in cosmic voids. In this talk, I show how PMFs can enhance the abundance of dark matter minihalos of masses between 10^3-10^-11 solar masses. I conclude by arguing that search for dark matter minihalos can potentially provide the most sensitive probe for PMFs.

Speaker: Pranjal Ralegankar (sissa)

PMF DM minihalos.pdf

Wed, June 4

Wednesday Morning I

32 Status and prospects for indirect Dark Matter searches

More than 80% of the matter in the Universe is made up of a substance whose nature remains one of the greatest mysteries in physics: dark matter. Although there is clear evidence of its existence and gravitational effects, no evidence has been found of dark matter interacting with Standard Model matter beyond gravity.
Astrophysical and cosmological observations serve as powerful tools to study a variety of dark matter scenarios and to constrain its interactions with conventional matter. In this talk, I will discuss the main signatures that different dark matter models would leave in astrophysical observations and comment on astrophysical anomalies that may be related to dark matter. Moreover, I will provide an overview of the current constraints and discuss the most suitable observations to probe dark matter.

Speaker: Pedro De la Torre Luque (Institute of theoretical physics (IFT-UAM))

DM2025_Santander_DelaTorreLuque.pdf

33 Unveiling low mass WIMP Dark Matter in the Galactic Centre through KM3NeT

The method of indirect detection of Dark Matter (DM) in neutrino telescopes involves the observation of a Cherenkov light pattern left by their annihilation or decay products crossing the detector. An excess of neutrinos produced by these processes is searched in astrophysical targets such as the Galactic Centre or the Sun, where large amounts of DM are believed to accumulate. An interesting candidate for a DM component are Weakly Interacting Massive Particles (WIMPs), as they would be consistent with gravitational evidence for DM and are expected to interact weakly with Standard Model particles. The KM3NeT infrastructure, located in abyssal sites of the Mediterranean Sea, includes multiple detectors, among which ORCA is optimized for measuring low-energy neutrinos. In its final configuration, ORCA will consist of 115 vertical detection lines, each containing 18 optical modules with 31 photomultiplier tubes that detect light signals. In this contribution we present an analysis with an unbinned likelihood method looking for WIMP-like DM annihilations occurring at the Galactic Centre, where we consider DM with masses ranging from approximately 10 GeV up to 1 TeV. We use various partial ORCA-detector configurations with 6, 10, 11, 15 lines to explore low masses.

Speaker: Adriana Bariego Quintana (IFIC)

Talk_KM3NeT_DM2025Conference_AdrianaBariegoQuintana.pdf

34 Probing dark matter annihilation through planetary airglow and internal heat flow

The annihilation of accumulated dark matter within planetary bodies could lead to observable signatures in the form of anomalous UV airglow and excess internal heat flow. We use existing UV and IR spectral data obtained by spaceprobe flybys of Solar System planets to constrain such effects. By comparing the measured spectra to potential dark matter-induced emissions, we place limits on scenarios where dark matter annihilation could contribute significantly to planetary emissions. We consider dark matter annihilating through both short- and long-lived mediators and account for the spatial distribution of dark matter within planetary interiors. Our results highlight planetary spectroscopy as a complementary approach for probing dark matter properties.

Speaker: Marianne Moore (MIT)

Santander_airglow.pdf

Santander_airglow.pptx

35 Celestial objects as Leptophilic dark matter detectors

With their large exposures from the heaven, celestial objects serve as natural dark matter detectors. For leptophilic dark matter, interactions with electrons inside these objects can lead to energy loss, allowing dark matter to become gravitationally bound. Using the Sun and observations by Super-Kamiokande, we set world-leading constraints on the dark matter–electron scattering cross section for dark matter masses above 4 GeV. For sub-GeV dark matter, we propose a novel approach by considering Jupiter as a capture target. This leads to the strongest existing constraints on sub-GeV leptophilic dark matter, probing a significant portion of the theoretically motivated parameter space in a class of hidden sector models.

Speaker: Thong T. Q. Nguyen (OKC, Stockholm University)

Santander_5min_short_Thong.pdf

36 Nano-Hertz gravitational waves and sub-GeV dark matter form a classically conformal phase transition

Strong first-order phase transitions offer a compelling explanation for the stochastic gravitational wave background in the nano-Hertz range measured by pulsar timing arrays (PTA). In this talk, I will consider a classically conformal dark sector in which the symmetry breaking of a dark $U(1)$ gives rise to a gravitational wave background that can fit the PTA data and additionally sources the mass of a stable fermionic sub-GeV dark mattercandidate. The model is coupled to the Standard Model via a dark photon mediator which is tightly constrained by laboratory searches. I will discuss these accelerator constraints as well as cosmological constraints coming from the decay of dark Higgs bosons after the phase transition. Finally I will present the results of a global fit and show that the model has viable parameter space where it fits the PTA data, reproduces the observed relic abundance and avoids all relevant constraints.

Speaker: Jonas Matuszak (Karlsruher Institute of Technology)

DM2025_JonasMatuszak.pdf

Conference Photo

11:30 AM Coffee Break

Wednesday Morning II

37 Dark Matter Production in Unusual Cosmologies

I will discuss how new physics can modify the cosmological history of the Universe at the time of dark matter production, and how this can dramatically change our inference of favored parameter space and what experimental searches for dark matter can expect to see.

Speaker: Tim Tait (University of California, Irvine)

Tait-Santander.pdf

38 BBN constraints on resonant DM annihilations

Dark Matter (DM) annihilations in the early universe can inject energy into the Standard Model (SM) plasma, impacting Big Bang Nucleosynthesis (BBN) through photodisintegration of light elements. Observed element abundances thus provide constraints on DM annihilation strength. I will present bounds on resonant DM models, where an additional particle with mass near twice the DM mass enhances annihilations—potentially leading to stringent BBN constraints.

Speaker: Pieter Braat (Nikhef)

DM2025_Braat.pdf

39 Round Table Discussion

1:30 PM Lunch

Thu, June 5

Thursday Morning I

40 Dark Matter at the LHC

The astrophysical evidence for dark matter provides compelling argument for the existence of physics beyond the Standard Model. Collider experiments such as ATLAS offer the ability to search for dark matter at high energy scales and characterise its interactions, and provide complementarity probes to direct and indirect dark matter detection searches and dedicated low mass dark matter experiments. LHC Run 2 (2015-2018) provided a hugely sensitive dataset for a wide range of potential dark matter candidates and models at ATLAS, CMS and LHCb. An overview of these search results will be presented, before a brief outlook to the ongoing LHC Run-3 and prospects for the High-Luminosity LHC phase to start in 2030.

Speaker: James Frost (University of Oxford)

DM2025.pdf

41 Searches for new physics using unconventional signatures or unconventional workflows using the ATLAS detector

Many theories beyond the Standard Model (SM) have been proposed to address several of the SM shortcomings. Some of these beyond-the-SM extensions predict new particles or interactions directly accessible at the LHC, but which would leave unconventional signatures in the ATLAS detector. These unconventional signatures require special techniques and reconstruction algorithms to be developed, enabling analysers to perform unique searches for new physics. Conversely, some searches for more standard models also make use of unconventional workflows to improve sensitivity. This talk will cover several such searches using the Run-2 dataset.

Speaker: Viktoriia Lysenko (Czech Technical University, Prague)

DarkMatter_25_06_05_ATLAS_v4.pdf

42 Searches for dark sector signatures from CMS (emerging jets, semivisible jets, SUEP)

Among the intriguing scenarios of new physics that provide explanation to several shortcomings of the Standard Model (SM), hidden valley scenarios include a Dark Sector that extends the SM with a non-Abelian gauge group, similar to quantum chromodynamics with new matter and gauge fields analogous to the SM quark and gluon fields. This may result in a rich phenomenology which we can access through portal interactions. In this talk we present the most recent results from CMS that explore such Dark Sectors by exploiting dedicated data streams and innovative usage of the CMS detector. We focus on the recent results obtained using the full Run-II data-set collected at the LHC.

Speaker: Cesare Cazzaniga (ETH Zürich)

presentation_DM2025.pdf

43 Constraining Dark Photon Kinetic Mixing in Heavy-Ion Collisions from SIS to LHC energies

Vector $U$-bosons, commonly known as 'dark photons', are hypothesized mediators of dark matter interactions. In this study, we establish a methodology to set theoretical constraints on the upper limit of the kinetic mixing parameter $\varepsilon^2(M_U)$ by analyzing dilepton spectra from heavy-ion collisions spanning SIS to LHC energies. Our approach relies on the microscopic Parton-Hadron-String Dynamics (PHSD) transport model, which accurately describes measured dilepton production in $p+p$, $p+A$, and $A+A$ collisions. In addition to the conventional dilepton sources from Standard Model processes, such as mesonic and baryonic interactions and decays, we extend the PHSD framework to incorporate dilepton decays of hypothetical $U$-bosons via $U \to e^+ e^-$. These $U$-bosons are produced via Dalitz decays of $\pi$, $\eta$, $\eta^{\prime}$, and $\omega$ mesons, as well as $\Delta$ resonances. Additional contributions arise from the decays of vector mesons $\rho,\omega,\phi$ and $K^+$ mesons. Our findings impose an upper bound on $\varepsilon^2(M_U)$ and highlight the precision required for future experimental searches for dark photons in dilepton channels.

Speaker: Adrian William Romero Jorge (Frankfurt Institute for Advanced Studies/Institut für Theoretische Physik, Johann Wolfgang Goethe-University/HFHF)

DM25_Adrian_Romero.pdf

DM25_Poster.pdf

11:30 AM Coffee Break

Thursday Morning II

44 Dark Photon Searches at LHCb

The LHCb experiment searches the existence of dark photons ($A'$) as potential mediators between the Standard Model and a hypothesized dark sector, which is expected to interact feebly with Standard Model (SM) particles through kinetic mixing. Results from Run 1 and Run 2, focusing on prompt and displaced dark photon decays into muon pairs ($A'→\mu^+\mu^-$), have set world-leading exclusion limits on the dark photon mass and kinetic mixing parameter at 90% C.L., including the first-ever limit outside of beam dump experiments in a displaced phase space region. The focus of this talk is on future prospects on the dark photon search with the Upgraded LHCb detector in Run 3. This new detector and new trigger capabilities enabled also an extended search for electron final states ($A'→e^+e^-$) to probe dark photon masses below the dimuon threshold, benefiting from enhanced particle identification, larger datasets and optimized soft trigger thresholds. The ongoing efforts aim to explore previously inaccessible phase space parameter space, with promising preliminary results from electron-based analyses and low-mass resonance searches.

Speaker: Carlos Eduardo Cocha Toapaxi (Heidelberg University)

Carlos_LHCb_DM25.pdf

45 Recent results on dark sector searches at Belle II

The Belle II experiment has unique reach for a broad class of models that postulate the existence of dark matter particles with MeV—GeV masses. This talk presents recent world-leading physics results from Belle II searches for Z' bosons, axion-like particles, and dark scalars in association with two muons in e+e- collisions; long-lived (pseudo)scalars produced in decays of B-mesons; inelastic dark matter; as well as the near-term prospects for other dark-sector searches.

Speaker: Foteini Trantou (University of Pisa)

DM2025_TFoteini.pdf

46 Consistent excesses in SUSY DM production at the LHC

In the SUSY DM searches, both ATLAS and CMS show consistent excesses in two independent search channels. While each of these four searches is at the 1-2 $\sigma$ level, it is the first time that all relevant channels show these consistent excesses. These searches indicate a DM mass (of the lightest neutralino) of about 200 GeV, with two more particles (the second lightest neutralino and the lightest chargino) only slightly heavier by about 25 GeV. We analyze which parts of the (N)MSSM parameter space yields a good description of these excesses. They may constitute the step towards the production of DM at the LHC.

Speaker: Sven Heinemeyer (IFT (CSIC, Madrid))

sven.pdf

47 DM at the ILC

Dark matter phenomenology in BSM models at future lepton colliders (focus on the ILC) are discussed. As an explicit example, a strategy for parameter determination of a supersymmetric DM candidate in the MSSM is presented. The importance of polarized beams and threshold scans is critically analyzed. Precision requirements of masses and cross sections are worked out and compared for the different collider options. Experimental constraints from LHC, cosmology, experiments and theory have been included.

Speaker: Gudrid Moortgat-Pick (University of Hamburg / DESY)

dm-ilc.pdf

1:35 PM Lunch

Thursday Afternoon I

48 Weakly interacting particles from beam-dumps & new NA62 results

The talk also aims at giving a short overview of the overall community attempts of new physics searches in proton beam-dumps.As a concrete example it will then focus on the NA62 experiment at CERN. This was designed to measure the highly-suppressed decay $K^{+} \rightarrow \pi^{+}\nu\bar{\nu}$, has the capability to collect data in a beam-dump mode, where 400~GeV protons are dumped on an absorber. In this configuration, New Physics particles, including dark photons, dark scalars and axion-like particles, may be produced and reach a decay volume beginning 80~m downstream of the absorber. This talk then presents in detail the newest analysis results from the search of these particles and their possible connection to Dark Matter.

Speaker: Babette Döbrich (MPP)

BabetteDöbrich_BeamDumps.pdf

49 Latest results from the NA64 experiment

NA64 is a fixed target experiment at the CERN Super Proton Synchrotron accelerator searching for Dark Sectors employing high energy electron, positron and muon beams. In this talk, we report its latest results on sub-GeV Dark Matter searches with the 2016-2022 statistics. With the new data, NA64 is starting to probe for the first time the very interesting region of parameter space motivated by benchmark Light Dark Matter models. The experiment can also probe a variety of well-motivated New Physics scenarios that will be briefly covered in this talk such as: ALPs, inelastic DM, B − L and $L_{\mu}-L_{\tau}$ $Z'$ boson searches. Moreover, in this contribution we will also present the first results of NA64 running in positron and muon modes as well as the future plans of the experiment.

Speaker: Mr Mirald Tuzi (IFIC (CSIC/UV))

tuzi_DarkMatter_5062025_final.pdf

50 Probing new physics at the LUXE experiment

The proposed LUXE experiment (LASER Und XFEL Experiment) at DESY, Hamburg, using the electron beam from the European XFEL, aims to probe QED in the non-perturbative regime created in collisions between high-intensity laser pulses and high-energy electron or photon beams. This setup also provides a unique opportunity to probe physics beyond the standard model. In this talk we show that by leveraging the large photon flux generated at LUXE, and by optimising the design setup to obtain a background-free experiment, one can probe axion-like-particles (ALPs) for masses around ~ 200 MeV and with photon couplings in the region of $10^{-5}~ \text{GeV}^{-1}$. This parameter space is yet unexplored by running experiments.

Speaker: Shan Huang (IFIC, Valencia)

LUXE_NPOD_DM2025-SH.pdf

4:30 PM Coffee break + Poster Session

Thursday Afternoon II

51 Cosmological concordance from the early universe to the near field

[Connecting via Zoom] Cosmological observables, from the Lyman-alpha forest to the Milky Way substructure, offer unique avenues for probing dark matter and neutrino sectors. Moreover, they often reveal anomalies and tensions that could signal new physics. I will review the status of the recent early-universe and late-universe searches for dark matter and neutrino interactions, highlighting in particular the new simulation and EFT based efforts to understand their effects on the distribution of matter on small scales. I will highlight the interplay between complementary probes and discuss cosmological concordance in light of new data and modeling efforts.

Speaker: Vera Gluscevic (University of Southern California)

Santander-2025-Gluscevic-shared.pdf

Santander-2025-Gluscevic-shared.pptx

52 Unexplained correlation between Local Matter Density Distribution and the Cosmic Microwave Background Temperature

Recent observations have revealed a Cosmic Microwave Background (CMB) temperature decrement toward local galaxies within the 2MASS Redshift Survey. We examine this detection by investigating its frequency dependence and sensitivity to component separation methods, indicating that Galactic foregrounds are unlikely responsible. Unlike previous studies, our findings show the decrement is independent of galaxy type, suggesting a possible correlation between the CMB and the overall matter density field. To investigate this hypothesis, we utilize three analytical methods: cross-correlation analysis, template fitting, and Bayes Factor calculation. Our results consistently demonstrate a moderate correlation (with significance levels between 1% - 5%) between the CMB and the 2MASS Redshift Survey projected matter density at distances under 50 Mpc/h. Notably, this signal is not detected beyond 50 Mpc/h, which limits potential physical interpretations and highlights the need for caution regarding possible look-elsewhere effects in our analysis. We discuss that the physical origin of this correlation may potentially be connected to dark matter distribution in galaxy halos. Additional research is necessary to validate and elucidate this relationship between the CMB and local matter distribution.

Speaker: Marcos Cruz (IFCA (UC-CSIC, Santander))

Santander_20250605.pdf

53 Impact of heavy axions on gamma-ray bursts

Short gamma-ray bursts (GRBs) are some of the brightest transients in the universe. Heavy axion-like particles (ALPs) can be produced in the hot plasma of GRB fireballs and escape, transporting energy away the from the source. When they decay outside the source, we show that the resulting photon field is too rarefied to re-thermalize, effectively preventing the re-emergence of the fireball, thus dimming or disrupting GRBs. Using existing observations of short GRBs, we place competitive bounds reaching ALP-photon couplings of $g_{a \gamma \gamma} \sim 4 \times 10^{-12}~\text{GeV}^{-1}$ for ALP masses between 200 MeV and 5 GeV.

Speaker: Oindrila Ghosh (OKC, Stockholm)

Oindrila_Ghosh_DM_Santander_talk.pdf

54 Quantum Technology searches for axion dark matter

Axion-like particles (ALPs) are compelling dark matter candidates, particularly in the "ultralight mass regime." In this talk, I will discuss the theoretical framework for ALP interactions with Standard Model fields, emphasising the renormalization group (RG) running and low-energy matching in quantum field theory. Many quantum sensor experiments are designed to probe very light ALPs, which are especially sensitive to these effects due to large decay constants where running effects become significant. Furthermore, while linear axion interactions are dictated by their pseudoscalar nature, quadratic interactions resemble scalar interactions, leading to distinct experimental signatures. I will explore the discovery potential of various quantum technology-based experiments, including atomic clocks, interferometers, haloscopes, and fifth force searches.

Speaker: Sreemanti Chakraborti (IPPP, Durham University)

DM2025_sreemanti.pdf

9:00 PM Conference Dinner - Gran Casino Sardinero

Fri, June 6

Friday Morning I

55 ANAIS-112 six-year results and future prospects

The ANAIS (Annual modulation with NaI(Tl) Scintillators) experiment is intended to search for dark matter annual modulation with ultrapure NaI(Tl) scintillators in order to provide a model independent confirmation or refutation of the long-standing DAMA/LIBRA positive annual modulation signal in the low energy detection rate, using the same target and technique. Other experiments exclude the region of parameters singled out by DAMA/LIBRA. However, these experiments use different target materials, so the comparison of their results depends on the models assumed for the dark matter particle and its velocity distribution in the galactic halo. ANAIS-112, consisting of nine 12.5 kg NaI(Tl) modules produced by Alpha Spectra Inc., disposed in a 3×3 matrix configuration, is taking data smoothly with excellent performance at the Canfranc Underground Laboratory, Spain, since August 2017. Results based on three-year exposure were consistent with the absence of modulation and not compatible with DAMA/LIBRA for a sensitivity of almost 3σ C.L. In this talk, the current state of the experiment and results with 6 years of data will be discussed. Updated sensitivity projections will be provided, foreseeing a 5σ sensitivity to the DAMA/LIBRA signal by the end of 2025.

Speaker: Iván Coarasa Casas (CAPA - Universidad de Zaragoza)

DarkMatter2025_ANAIS112_IvanCoarasa.pdf

56 COSINUS - cross-checking the DAMA/LIBRA signal using cryogenic NaI detectors

The signal measured by the DAMA/LIBRA experiment matches the expectations of an annually modulating signal caused by particle dark matter (DM) from the galactic halo with very high statistical significance. At the same time, this result is in strong tension with null results from many other DM direct detection experiments. These tensions, however, critically depend on assumptions about the exact nature of DM, its interaction mechanism with the Standard Model, and other systematic uncertainties. An unambiguous, model- and detector-material-independent cross-check is therefore crucial, yet still pending.

The COSINUS experiment, located at the LNGS (Laboratori Nazionali del Gran Sasso) in Italy, will answer whether the signal recorded by the DAMA/LIBRA collaboration can originate from DM nuclear recoils. To achieve this, COSINUS employs ultrapure NaI crystals operated as cryogenic scintillating calorimeters, which renders it unique among NaI-based experiments (like DAMA/LIBRA) and allows a cross-check that is both DM-model- and quenching-factor-independent. This key technology is a combination of 1) using transition edge sensors (TESs) on NaI crystals at millikelvin temperatures to measure phonon signals caused by particle interactions, and 2) additionally capturing the scintillation light. The resulting advantages include a low threshold for nuclear recoils, absolute energy calibration using the phonon channel, superior energy resolution, and effective discrimination of electromagnetic backgrounds on an event-by-event basis due to the dual-channel readout.

This talk will discuss the latest results from the COSINUS prototype detectors, the status of the novel cryogenic low-background facility located at the LNGS, and the last steps of the commissioning towards starting the first physics data-taking campaign in late 2025.

Speaker: Philipp Schreiner (HEPHY, TU Wien)

2025_06_06_COSINUS_SCHREINER.pdf

57 The SABRE South Experiment at the Stawell Underground Physics Laboratory

SABRE is an international collaboration that will operate similar particle detectors in the Northern (SABRE North) and Southern Hemispheres (SABRE South). This innovative approach distinguishes possible dark matter signals from seasonal backgrounds, a pioneering strategy only possible with a southern hemisphere experiment. SABRE South is located at the Stawell Underground Physics Laboratory (SUPL), in regional Victoria, Australia.
SUPL is a newly built facility located 1024 m underground (∼2900 m water
equivalent) within the Stawell Gold Mine and its construction has been completed in 2023.
SABRE South employs ultra-high purity NaI(Tl) crystals immersed in a Linear Alkyl Benzene (LAB) based liquid scintillator veto, enveloped by passive steel and polyethylene shielding alongside a plastic scintillator muon veto. Significant progress has been made in the procurement, testing, and preparation of equipment for installation of SABRE South. The SABRE South muon detector and the data acquisition systems are actively collecting data at SUPL and the SABRE South’s commissioning is planned to be completed by the end of 2025.
This presentation will provide an update on the overall progress of the SABRE South construction, its anticipated performance, and its potential physics reach.

Speaker: Sharry Kapoor (The University of Sydney and ARC Centre of Excellence for Dark Matter and Particle Physics)

DM2025 (1).pdf

DM2025.pptx

58 Advances in searching for axions with MADMAX

The MAgnetized Disk and Mirror Axion eXperiment (MADMAX) is a future experiment for the search of axion dark matter. Its detection principle is based on the conversion of axions into photons in a magnetic field. The axion to photon conversion is enhanced by a booster made of dielectric disks placed in front of a mirror. In its final version, MADMAX aims to scan the uncharted QCD axion mass range from 40 to 400 $\mu$eV, favoured by post-inflationary theories.
Several small-scale prototype systems have been developed and used to validate the experimental principles. As a result of this, first competitive limits on axion dark matter and on dark photons have been lately released.
This talk will discuss the latest progress of the experiment and its prototypes, highlighting ongoing research, development efforts, and remaining challenges.

Speaker: Dagmar Kreikemeyer-Lorenzo (Max Planck Institute for Physics)

MADMAX_DKreikemeyerLorenzo_Santander2025.pdf

11:30 AM Coffee break

Friday Morning II

59 Primordial black hole accretion in astronomical and cosmological settings

Massive primordial black holes may accrete baryonic matter and accretion disk are expected to form around them. The radiation emitted in this process can reveal their presence both in astronomical and cosmological settings.
In order to compute realistic constraints, it is critical to understand accretion physics. In this talk I will discuss an accretion model that takes into account radiation feedback, and present several applications aimed at deriving bounds on the PBH abundance above the solar mass.
I will mention astronomical searches focused in the inner Galaxy, analyze the cosmological bound arising from the CMB angular power spectrum, and conclude with an outlook towards future data from SKA and HERA in the context of 21 cm cosmology.

Speaker: Daniele Gaggero (INFN Pisa)

DMSantander_DG.pdf

60 The Canfranc Axion Detection Experiment (CADEx): a novel haloscope search for Dark Matter axions in the mass range 330–460 μeV

A range of haloscope searches are currently probing axions in the mass range ~2-40 μeV. However, simulations of the axion field in the early Universe are increasingly pointing towards heavier masses if we want the axion to comprise all of the Dark Matter in the Universe. I will briefly review these developments and then I will present The Canfranc Axion Detection Experiment (CADEx), a proposed haloscope search in the well-motivated but currently under-explored mass range 330-460 μeV. CADEx, to be installed at the Canfranc Underground Laboratory, will consist of an array of microwave resonant cavities in a static magnetic field, coupled to a highly sensitive detecting system based on Kinetic Inductance Detectors. I will present the timeline for CADEx as well as forecasts for its sensitivity to axions and dark photons.

Speaker: Alicia Gómez (CAB (CSIC-INTA))

AliciaGomez_DM2025.pdf

61 Discovering Axion-like particles using Multi-band observations of Galaxy clusters and CMB as a backlight.

Axions or axion-like particles (ALPs) are hypothetical particles predicted by various BSM theories, which make one of the dark matter candidates. If ALPs exist in nature, the CMB photons as they pass through galaxy clusters will convert to ALPs (of mass range $10^{-11}-10^{-14}$ eV), resulting in a polarized spectral distortion in the CMB. The resonant conversions dominate over the non-resonant ones, and occur when the effective masses of the photon and ALP are equal. The probability of this conversion will depend on the mass of ALPs, photon-ALP coupling constant $g_{a\gamma}$, electron density and transverse magnetic field profiles of the clusters, as well as the photon frequency at the conversion location. If galaxy clusters are resolvable in various frequency bands, their astrophysical information can be obtained. We have developed a multi-band framework, SpectrAx, which uses radio synchrotron observations (say, with SKA), to obtain the transverse magnetic field profiles of clusters. Through X-ray observations (say, with eROSITA), their electron density and temperature profiles can be constrained. Using the spectral and spatial information of the CMB, the ALP signal from these clusters can be estimated. Such a signal will result in an increase in the CMB power spectrum along the cluster line of sight at high multipoles, following the spectrum of the ALP signal. The clusters that are unresolved , will create a diffused ALP background in the microwave sky and can be studied using the distribution of clusters across different redshifts. These two regimes can be probed using the upcoming CMB experiments, such as the Simons Observatory and CMB-S4, which will be able to provide bounds $(g_{a\gamma}< 4\times{10}^{-12} \, \mathrm{GeV}^{-1})$ more than an order better than the current bounds from CAST $(g_{a\gamma}< 6.6\times{10}^{-11} \, \mathrm{GeV}^{-1})$.

Speaker: Harsh Mehta (Tata Institute of Fundamental Research, Mumbai)

DM2025_Talk.pptx

62 Axion population inside magnetized neutron stars

We study the axionic field structure inside magnetized neutron stars where a non-vanishing magnetic field is present. Typically magnetic field strength may be as large as 1e15 G in the surface for magnetars and a few orders of magnitude larger in the very central core. We explore the additional effect of a tiny electric field under the non-perfect conductor approximation using hypothetical scalar or pseudoscalar axion nature. We find that phenomenological constraints from neutron stars yield an effective constraint on the coupling and axion mass parameter space.

Speaker: M. Angeles Perez-Garcia

DM2025_mperezga_USAL.pdf

63 Impressions from DM2025

Speaker: Tim Tait (University of California, Irvine)

64 Closing Remarks

Speaker: Bradley Kavanagh

ClosingRemarks_DM2025.pdf