Using stars as natural laboratories for fundamental physics is an idea with deep roots, but recent years have seen a dynamic resurgence in this approach. In this talk, we will explore how stellar observations - both historical and cutting-edge - are shedding light on axions and other feebly interacting particles. By tracing the evolution of these ideas, from classic arguments to modern...
Pseudo-scalar axions are ubiquitous in high-energy theory, and so are their scalar partners, here called ‟dilatons”, that dynamicalise the corresponding gauge couplings. In this talk, I will discuss the cosmology of dilatons and axions, focussing on the impact of dilaton phase transitions. First, I will show how cosmological dilaton phase transitions can lead to the trapping and compression of...
In this talk, we will study minimal versions of Higgs inflation in the presence of a massless QCD axion. While the inflationary energy scale of the metric variant is too high to accommodate isocurvature bounds, it was argued that Palatini Higgs inflation could evade these constraints. We show, however, that an energy-dependent decay constant enhances isocurvature perturbations, implying that...
NA64 is a fixed target experiment at the CERN Super Proton Synchrotron accelerator searching for Dark Sectors employing high-energy electron, positron, hadron, and muon beams. This talk reports the 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...
At DESY in Hamburg, the ALPS group is developing detection systems for rare event searches based on superconducting Transition Edge Sensors (TES) together with international partners. In addition to the activities regarding an application within the ALPS II experiment, the TES platform at DESY has been adapted for direct detection of sub-MeV dark matter (DM) particles. Profiting from their low...
We explore the prospects for indirect dark-matter (DM) detection through gamma-ray emission from the annihilation of weakly interacting massive particles (WIMPs). Within the ΛCDM cosmological framework, hierarchical structure formation predicts the existence of DM halos and subhalos. If WIMPs constitute DM, they are expected to annihilate within subhalos, emitting gamma rays detectable by...
Axions and Axion-Like-Particles (ALPs) are theoretically well-motivated candidates for dark matter that, due to their large occupation number, can be described as oscillating classical fields. These particles may feature a quadratic interaction with ordinary matter which can modify the field's dynamics in the vicinity of such objects, inducing a very interesting phenomenology. In this talk, I...
In this talk I will do three things. First, I will outline the conditions under which the interaction rate of inelastic processes with a system consisting of N targets scales as N^2. Second, I will present computations of interaction rates for several weakly interacting particles, including the Cosmic Neutrino Background and Axion Dark Matter, and will explain the underlying physics. Third, I...
Electron capture (EC) decays of Xe-125 and Xe-127 constitute a known background in dark matter searches with dual phase xenon time projection chambers (TPCs) such as the LUX-ZEPLIN (LZ) experiment. The signals produced by these processes present a lower charge-to-light ratio compared to β-particle interactions of the same energy, which is attributed to enhanced recombination at the EC site as...
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 inflation.
The CRESST-III (Cryogenic Rare Event Search with Superconducting Thermometers) experiment is looking for the direct detection of dark matter particles via their scattering off target nuclei in cryogenic detectors, operated at mK temperatures. Energy thresholds of O(10 eV) allow for the search of sub-GeV dark matter masses, making CRESST one of the leading experiments in the low-mass DM regime....
We present recent developments from The Oscillating Resonant Group AxioN (ORGAN) Collaboration, focusing primarily on two experimental platforms beyond the main experiment - ORGAN-Q and ORGAN-Low Frequency (ORGAN-LF) - designed to expand axion parameter space coverage and test technologies for future searches.
ORGAN-Q is a pathfinding and testbed experiment targeting the range around ~25...
Recent Gaia observations, together with advances in the theory of stellar evolution, open up the possibility to study color-magnitude diagrams of Galactic globular clusters with unprecedented accuracy. In particular, lists of cluster members, their metallicity, helium mass fraction, age, distance from the Sun, and reddening can be precisely determined. We present our study of 35 Galactic...
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...
This talk will provide an overview of quantum sensing and its
emerging applications in fundamental physics. In particular, it will
highlight the use of qubits, the foundational units of quantum computing
as novel sensors capable of detecting single quanta of energy beyond the
reach of traditional dark matter detection methods.
The axion remains a compelling dark matter candidate, yet a substantial portion of its potential mass range remains unexplored. Post-inflation QCD axion string models suggest that axions could possess higher masses than what current haloscopes can detect. Traditional tunable cavity-based haloscopes have shown exceptional sensitivity at lower frequencies, but their effectiveness diminishes at...
In this talk I will introduce angular redshift fluctuations (ARF), a novel cosmological observable that, contrary to other standard probes that measure the counts and the shapes of galaxies, looks at the galaxies' redshifts and their fluctuations when projected under any given redshift shell. I will show ARF are found to be extremely sensitive to radial peculiar velocities, and also to the...
In this talk I want to discuss the (unorthodox) scenario when the baryogenesis is replaced by a charge separation process in which the global baryon number of the Universe remains zero. In this, the so-called axion quark nugget (AQN) dark matter (DM) model the unobserved antibaryons come to comprise the dark matter in the form of nuclear density nuggets. In this talk I specifically focus...
The inflationary diffusion of (pseudo-)scalar fields with discrete symmetries can seed the formation of a gas of closed domain walls after inflation, when the distance between degenerate minima in field space is not too far from the inflationary Hubble scale. Primordial black holes (PBHs) can then be formed once sufficiently heavy domain walls re-enter the Hubble sphere. In this scenario,...
Axion and axion-like particles are hypothesized to interact with photons, inducing a time-varying
rotation in the polarization of linearly polarized laser light. This work presents a highly sensitive
apparatus designed to detect this rotation. The setup employs a polarimetry configuration featuring
two quarter-wave plates inside a Fabry-P´erot cavity, allowing us to investigate unexplored...
Dark matter candidates such as axions and dark photons can generate coherent, oscillating magnetic fields at the Earth’s surface, arising from boundary conditions between the conductive Earth and the ionosphere. The Search for Non-Interacting Particles Experiment (SNIPE) collaboration employs a global network of magnetometers in radio-quiet locations to search for these signals. An update on...
According to the ΛCDM model, spectral distortions of the CMB from a perfect blackbody shape are expected. The COBE experiment was the first to measure the absolute spectrum of the CMB in the 1 to 95 cm⁻¹ frequency range, but it did not detect any deviations from a pure blackbody. Absolute measurements of the CMB at longer wavelengths than those covered by COBE have been performed by a few...
Conventional closed resonator haloscopes become increasingly ineffective at probing axion masses above $\sim 40 \mathrm{\mu eV} $, as their effective volume scales as $V_\mathrm{eff} \propto 1/m_a^{3}$, leading to a steep decline in signal power with increasing mass. Open resonators, in contrast, relax the transverse boundary conditions, resulting in a more favorable scaling of $V_\mathrm{eff}...
In 2022, GRB221009A was detected by the LHAASO collaboration as the brightest gamma-ray burst (GRB) ever recorded with photon energies that extended up to 18TeV. Combined with the redshift of $z=0.151$ of the GRB, it has been questioned whether these observations can be reconciled with standard physics, since such high energy photons suffer from absorption on the extragalactic background light...
Axion-like particles and similar new pseudoscalar bosons coupled to nucleons and electrons are known to lead to spin-dependent forces in atoms and ions. We argue that hyperfine structure measurements in the hydrogen- and lithium-like charge states are a sensitive probe to this effect. Focusing on specific differences reduces uncertainties due to nuclear effects in hyperfine structure...
Neutrinos are elementary particles that interact only very weakly with matter. Neutrino experiments are therefore usually big, with masses on the multi-ton scale. The thresholdless interaction of coherent elastic neutrino-nucleus scattering (CEνNS) leads to drastically enhanced interaction rates, which allows for much smaller detectors. This could open the path for reactor monitoring through...
Cosmological models featuring QCD axions or axion-like particles (ALPs) can face a serious domain wall (DW) problem when the domain wall number $N_{DW}$, exceeds unity. While biased potentials are a commonly proposed solution, we explore alternative mechanisms based on thermal plasma friction.
Using techniques from nonequilibrium quantum field theory, we evaluate the quantum equations of...
A critical challenge in cavity haloscope experiments is the development of fast and wide-range frequency tuning systems. One promising approach is to incorporate qubits based on DC SQUIDs into the cavity, where the qubit-cavity interaction is controlled by an external magnetic flux [1]. This non-mechanical method is particularly attractive for fast scanning, as it avoids the frictional heating...
We explore how gravitational wave detectors, such as LIGO and Virgo, can be leveraged to search for spin-2 ultralight dark matter. These particles are expected to produce a continuous signal, making them well-suited for search methods originally developed for continuous gravitational waves. In this context, we develop a search using the Band Sampled Data framework (a gravitational wave data...
Axion-like particles (ALPs) can be copiously produced in binary neutron star (BNS) mergers through nucleon-nucleon bremsstrahlung if the ALP-nucleon couplings $g_{a N}$ are sizable. Furthermore, the ALP-photon coupling $g_{a\gamma}$ may trigger conversions of ultralight ALPs into photons in the magnetic fields of the merger remnant and of the Milky Way. This effect would lead to a potentially...
The Any Light Particle Search II (ALPS II), a light-shining-through-a-wall experiment located in Hamburg, Germany at the Deutsches Elektronen-Synchrotron (DESY), completed its first science runs in early 2024. The experiment principally searched for axions and axion-like particles in two data-taking stretches deemed a "scalar" run and a "pseudoscalar" run. The analysis of the data from these...
The RADES (Relic Axion Detector Experimental Setup) collaboration is dedicated to the search for axions, hypothetical particles that are compelling dark matter candidates and a natural solution to the strong CP problem in QCD. Our approach focuses on haloscope detectors, a well-established technique that exploits the axion-photon conversion in strong magnetic fields and resonant cavities. Over...
Axion-like particles (ALPs) are promising candidates for new physics beyond the Standard Model, motivated by their potential to resolve one of the greatest mysteries of the Universe: Dark Matter (DM). Their ability to oscillate into photons in the presence of an external magnetic field, leads to expected signatures imposed on the observed photon spectra of astrophysical sources. In gamma-ray...
"The QCD axion is a well-motivated hypothetical particle that simultaneously addresses the strong CP problem and
constitutes a compelling cold dark matter candidate. The MADMAX experiment (Magnetized Disk and Mirror Axion
Experiment) is designed to search for axions in the mass range around 100 μeV by boosting the microwave radiation in induced by the inverse Primakoff effect in a dielectric...
Even before Wilczek and Weinberg proposed the quantum chromodynamic (QCD) axion as a new light boson beyond the standard model, Sato and Sato used astrophysical considerations to suggest that such a particle cannot have rest-mass energy around 0.5 eV. A decade later, Turner and Raffelt used the observation of the neutrino pulse from supernova 1987A to come to the same conclusion. But a decade...
A new window to the universe was opened up with the detection of gravitational waves. While observations have been made at frequencies around hundreds of herz, and evidence was found at nHz frequencies, the high frequency region is still unexplored experimentally. To change this the GravNet initiative was founded with the aim to setup a global network of high frequency gravitational wave...
Axion dark matter thermalizes by gravitational self-interactions and forms a Bose-Einstein condensate. It is shown that the rethermalization of the axion fluid during the initial collapse of large scale overdensities at cosmic dawn transports angular momentum outward sufficiently fast that black holes form with masses ranging from approximately $10^5$ to a few times $10^{10}~M_\odot$.
The axion is a well-motivated hypothetical particle that could account for dark matter. In strong magnetic fields, such as those surrounding neutron stars and magnetars, axions can convert into photons, a process that could, in principle, produce detectable electromagnetic signatures. Traditionally, searches have focused on the microwave (centimeter wave regime), corresponding to axion masses...
Blazars are a class of active galactic nuclei, supermassive black holes located at the centres of distant galaxies characterised by strong emission across the entire electromagnetic spectrum, from radio waves to gamma rays. Their relativistic jets, closely aligned to the line of sight from Earth, are a rich and complex environment, characterised by the presence of strong magnetic fields over...
The LUX-ZEPLIN (LZ) experiment features a dual-phase xenon time projection chamber designed to detect weakly interacting massive particles (WIMPs) with unprecedented sensitivity. Among its backgrounds, scintillation-only events are particularly challenging to study due to their small size and consequential poor spatial reconstruction; yet, they play a significant role by contributing to...
Dark photon is one of the candidates for cold dark matter, predicted by specific models of string theories and high-scale inflation models. Dark photons interact with ordinary photons via the coupling constant $\chi$. Owing to this interaction, the dark photons convert into millimeter-wave light at electromagnetic boundaries, such as the surface of a metal plate. The frequency of the...
String theory models generically lead to a large number of axion-like particles (ALPs), known as the string axiverse. I will discuss the possible astrophysical and experimental signatures of the string axiverse, and how the phenomenology of many ALP systems differs from that of a single ALP or axion.
We present a unified program of complementary experiments targeting axions, axion-like particles (ALPs), and high-frequency gravitational waves (HFGWs) across a broad range of masses and couplings. The WISPFI experiment probes ALPs in the 28 to 100 meV range using resonant photon-axion conversion in a fiber-based interferometer with hollow-core photonic crystal fibers inside a magnetic field....
I will discuss recent progress on the understanding of the production of light dark matter in core-collapse supernova explosions. This leads to not only a constraint in the relevant parameter space due to cooling arguments of SN 1987A but also to a range of phenomenological consequences that can open new venues for detection. In particular, we will focus on the application to sub-GeV dark...
Physics beyond the standard model can be probed via the
birefringence effects associated with axion dark matter backgrounds or a
passing gravitational wave (GW). Exploiting the unified formalism
between axion and high frequency GW effects, the use of optical cavities
offer an opportunity for pre-existing experiments to adapt themselves to
measure these polarization shifts. We demonstrate...
Ultraprecise mechanical sensors such as magnetically levitated (Maglev) superconductors offer new ways to test the coupling between ultra-light dark matter and electromagnetism. In this talk, building on the ideas and technology proposed for spin-0 and spin-1, I will show how magnetically levitated resonators can be used as detectors for spin-2 dark matter, also known as dark gravitons. I will...
We present the design and simulation results of a superconducting quantum sensor aimed at the direct detection of axion and hidden photon dark matter in the microwave regime. These dark matter candidates are predicted to convert into microwave photons at very low event rates through their weak coupling to electromagnetic fields, posing a significant experimental challenge.
To overcome this,...
New light CP-even scalars arise in a variety of BSM scenarios aimed at solving the dark matter puzzle, generating neutrino masses and/or tackling the electroweak hierarchy problem. I will discuss supernova cooling constraints on new scalars that mix with the Higgs, couple only to nucleons, or couple only to leptons. In all these cases scalars with masses smaller than the plasma frequency in...
The Relic Axion Detector Exploratory Setup (RADES) Collaboration works on the development of new techniques for axion haloscopes. In 2021 we performed a haloscope axion search performed using a custom-made radio-frequency cavity coated with high-temperature superconducting tape, using an 11.7 T dipole magnet at CERN. We will present the results of the search, after analysing a set of 27 h of...
The particles composing the dark matter are thought to be distributed in haloes around the galaxies and then, they can be detected on Earth-based very sensitive instruments if they couple to normal matter other than gravitationally. Direct dark matter searches sensitivity has been steadily improving for about forty years, profiting from the development of new detection strategies, application...
DALI (Dark-photons & Axion-Like particles Interferometer) is a next-generation haloscope experiment targeting the 25–250 μeV mass range in the search for axion dark matter. It introduces a novel experimental approach based on a magnetized phased array (MPA) architecture and a tunable resonator, offering significant advantages over conventional designs.
This presentation will outline the DALI...
The KM3NeT experiment, a next-generation neutrino observatory under construction in the depths of the Mediterranean Sea, aims to reveal the mysteries of the high-energy Universe by detecting neutrinos originating from astrophysical sources. In this talk, we present the observation of a high-energy neutrino event recorded by the KM3NeT detector, marking a significant milestone in its scientific...
WISPFI (WISP Searches on a Fiber Interferometer) is a novel table-top experiment designed to detect photon-axion conversion using resonant mixing. The experiment employs hollow-core photonic crystal fibers (HC-PCF) to fulfill the resonant condition, which can be precisely tuned by adjusting the gas pressure within the fiber. This technique enables the probing of an unexplored axion mass range...
A collaboration between three main laboratories of CNRS, Université Grenoble-Alpes and DMAG/IBS in South Korea (ex-CAPP) is bringing together key expertises to build and operate several haloscopes for axion dark matter searches with unprecedented sensitivity. Based on existing infrastructures at Grenoble like the 9 T/43 T modular hybrid magnet of LNCMI recently put in operation up to 8.5 T/42...
The large-scale structure of our Universe is well described by a model in which matter is predominantly Cold Dark Matter (CDM). While CDM was initially thought to have trouble reproducing observations of dwarf galaxies, it has generally become accepted in the last decade that a proper treatment of the gas and stars (baryonic matter) can alleviate those tensions. However, the models of...
First proposed to solve the strong CP problem, axions are also plausible candidates for dark matter as they are expected to have a mass and as they have seemingly weak interactions with known particles. The Cosmic Axion Spin Precession Experiment (CASPEr) encompasses multiple projects using nuclear magnetic resonance (NMR) to search for axion dark matter. The CASPEr-Gradient Low Field (LF) and...
Axions with a mass around 1 eV can decay into near-infrared photons. Utilising blank-sky observations from the James Webb Space Telescope, I search for a narrow emission line due to decaying dark matter and derive leading constraints on the axion-photon coupling in the eV-scale mass range.
The fifth force may arise due to “new physics” beyond the Standard Model. We focus on the spin-dependent fifth forces [1] that are mediated by new particles, such as spin-0 particles (axion and axion-like particles) and spin-1 particles (e.g., light Z’ particle or massless paraphoton). These new ultralight particles are also candidates for dark matter and dark energy, and may also break...
As direct detection experiments continue to tighten constraints on heavy WIMPs, the low-mass region of the dark matter (DM) parameter space remains largely unexplored. Detecting Light Dark Matter (LDM) requires both sub-keV energy thresholds and large exposure. While solid-state detectors can achieve energy thresholds on the order of 10 eV, their limited target mass restricts the achievable...
The DMRadio series of experiments is designed to probe pre-inflationary dark matter axions in the peV-neV range. Specifically, DMRadio-GUT is the ultimate DMRadio experiment with sensitivity to dark matter axions at DFSZ coupling in the 0.4-120 neV (100 kHz-30 MHz) range. To achieve this sensitivity to DFSZ axions at such low masses, new technologies are necessary to scan the desired parameter...
Axion-like particles (ALPs) are a class of hypothetical bosons beyond the standard model of particle physis, which are
very weakly-interacting and long- lived. Since many ALPs may be produced in hot plasma in supernovae (SNe), a nearby
SNe Ia can be used as a probe of ALPs. It is desirable to predict the ALP emission from SNe Ia to discuss a possible
constraint that can be obtained from the...
We present a search for hidden photon dark matter using superconducting qubits, based on the method proposed by our group (Moroi et al., Phys. Rev. Lett. 131, 211001 (2023)). Hidden photon dark matter induces an AC electric field through the kinetic mixing with ordinary photons. This electric field can excite a qubit on resonance. Assuming that fake excitations are uniformly distributed in...
We report the QUAX haloscope improvements for the search of post-inflationary QCD axions at about $10\,$GHz frequency. With respect to previous QUAX results, a wide-tuning system is introduced and proved to work in a quasi-automatic protocol.
The haloscope resonator is a cylindrical copper cavity with a sapphire inner cylinder, which allows for a higher effective volume compared to an empty...
We present evidence for deviations from the collisionless Cold Dark Matter (CDM) paradigm. In the standard model, dark matter (DM) is collisionless and forms halos with dense central cusps, known as NFW profiles. However, observed galaxies often exhibit flat central cores, typical of systems in thermodynamic equilibrium. While baryonic processes can transform cusps into cores in more massive...
The plasma haloscope is a promising variant of cavity haloscope for axion dark matter searches, employing an array of equidistant metallic wires. ALPHA is a global collaboration dedicated to the development and operation of such plasma haloscope experiments. The resonant frequency of these wire-array cavities is primarily determined by the inter-wire spacing, enabling access to higher mass...
Cryogenic transition edge sensors (TESs) are single photon detectors featuring high quantum efficiency and excellent energy resolution below 10% at optical and near-infrared wavelengths. If thermal backgrounds can be suppressed to sufficiently low levels, such detectors would be ideally suited for experiments searching for photon-axion conversion at these wavelengths such as...
