Mon·May 19, 2025Monday·May 19, 2025

1. 01*

   Unearthing large pseudoscalar Yukawa couplings with Machine Learning

   Fernando Abreu de Souza🇵🇹 · Rafael Boto🇵🇹 · Miguel Crispim Romão🇬🇧 · Pedro N. Figueiredo🇵🇹 · Jorge C. Romão🇵🇹 · João P. Silva🇵🇹

   With the Large Hadron Collider's Run 3 in progress, the 125 GeV Higgs boson couplings are being examined in greater detail, while searching for additional scalars. Multi-Higgs frameworks allow Higgs couplings to significantly deviate from Standard Model values, enabling indirect probes of extra scalars. We consider the possibility of large pseudoscalar Yukawa couplings in the softly-broken Z2xZ2' three-Higgs doublet model with CP violating coefficients. To explore the parameter space of the model, we employ a Machine Learning algorithm that significantly enhances sampling efficiency. Using it, we find new regions of parameter space and observable consequences, not found with previous techniques. This method leverages an Evolutionary Strategy to quickly converge towards valid regions with an additional Novelty Reward mechanism. We use this model as a prototype to illustrate the potential of the new techniques, applicable to any Physics Beyond the Standard Model scenario.

   hep-phphysics.comp-phJHEP(2025)·11 citations
2. 02*

   Spontaneous Magnetogenesis at the Electroweak Phase Transition

   Valerie Domcke🇨🇭 · Yohei Ema🇨🇭 · Teerthal Patel🇺🇸

   Spontaneous CP violation during the electroweak phase transition can induce a twisting of the magnetic field configuration of Standard Model dumbbells, resulting in sizable intergalactic magnetic fields and a small baryon asymmetry, in agreement with observations. We demonstrate this by coupling the electroweak gauge group of the Standard Model to an axion-like particle with a non-vanishing velocity. Studying the resulting monopole, string and dumbbell configurations, we conclude that the helicity fraction of the magnetic fields generated at the electroweak phase transition is roughly given by the dimensionless axion velocity.

   hep-phastro-ph.COhep-thJCAP(2025)·2 citations
3. 03*

   Distribution Functions of $\Lambda$ and ${\Sigma }^0$ Baryons

   Yang Yu🇨🇳 · Peng Cheng🇨🇳 · Hui-Yu Xing🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳

   Treating baryons as quark + interacting-diquark bound states, a symmetry-preserving formulation of a vector$\times$vector contact interaction (SCI) is used to deliver an extensive, coherent set of predictions for $\Lambda ,{\Sigma }^0$ baryon unpolarised and polarised distribution functions (DFs) -- valence, glue, and four-flavour separated sea -- and compare them with those of a like-structured nucleon. $\Lambda ,{\Sigma }^0$ baryons are strangeness negative-one isospin partners within the SU$(3)$-flavour baryon octet. This makes such structural comparisons significant. The study reveals impacts of diquark correlations and SU$(3)$-flavour symmetry breaking on $\Lambda$, ${\Sigma }^0$ structure functions, some of which are significant. For instance, were it not for the presence of axialvector diquarks in the ${\Sigma }^0$ at the hadron scale, the $s$ quark could carry none of the ${\Sigma }^0$ spin. The discussion canvasses issues that include helicity retention in hard scattering processes; the sign and size of polarised gluon DFs; and the origin and decomposition of baryon spins. Interpreted judiciously, the SCI analysis delivers an insightful explanation of baryon structure as expressed in DFs.

   hep-phhep-exhep-latnucl-ex+1EPJA(2025)·8 citations
4. 04*

   An Analytic Prescription for $t$-channel Singularities

   Kento Asai🇯🇵 · Nagisa Hiroshima🇯🇵 · Joe Sato🇯🇵 · Ryusei Sato🇯🇵 · Masaki J. S. Yang🇯🇵

   The $t$-channel singularity is a divergence in the scattering amplitude which occurs when a stable particle propagating in $t$-channel scattering process becomes an on-shell state. Such situations appear either in the system of collider experiments or in the context of the cosmological particle production. No scheme which is generally applicable is known. In this work, we propose a new formulation to identify and remove the source of the divergence. The scheme is fully analytical and various applications can be expected. This work provides a valuable tool in this research field.

   hep-phPRD(2025)·1 citation
5. 05*

   Angular structure of Drell-Yan reaction in the TMD factorization approach

   Alexey Vladimirov🇪🇸

   We study angular distributions in the Drell-Yan process using an extended transverse momentum dependent (TMD) factorization framework that includes kinematic power corrections. This approach allows the description of observables previously considered power-suppressed. The results show good agreement with experimental data and provide the first LHC-based indication of the Boer-Mulders function, highlighting the value of power corrections in TMD phenomenology.

   hep-ph1 citation
6. 06*

   Some Aspects of Three-Quark Potentials (Part II)

   Oleg Andreev🇩🇪

   We continue our investigation of the effective string model for the triply heavy quark system, mimicking that in pure $SU(3)$ gauge theory. We present analytical and numerical studies of the three-quark potential for isosceles and collinear geometries. In the general case, we derive the asymptotic expression of the potential in the infrared limit. Here we also demonstrate the universality of the string tension and interpret the transition between two distinct regimes, occurring when one of the triangle's angles formed by the quarks is equal to $\frac{2}{3}\pi$, as a breaking of permutational symmetry. This symmetry breaking implies the emergence of a heavy quark dressed by gluons, transforming in the two-index antisymmetric representation. Additionally, we discuss various aspects of the $Y$- and $\Delta$-laws, diquarks, and connections to lattice QCD.

   hep-phhep-lathep-thnucl-thPRD(2025)·3 citations
7. 07*

   Depolarization of synchrotron radiation of a relativistic electron beam

   O. Novak🇺🇦 · M. Diachenko🇺🇦 · R. Kholodov🇺🇦

   We present a theoretical study on the radiative self-polarization of a high-energy electron beam propagating perpendicular to a strong magnetic field. Recently, a similar setup has been proposed as a source of polarized electron and photon beams. We focus on the dependence of electron and radiation polarization on the dimensionless parameter $\epsilon$, which is proportional to the product of electron energy and magnetic field strength. The numerical solution of the balance equation shows that the resulting electron beam polarization increases rapidly as a function of $\epsilon$ for $\epsilon \ll 1$ and saturates at a value of approximately $-0.8$. If $\epsilon \gg 1$, the rate of self-polarization decreases significantly. At the same time, a substantial or nearly complete depolarization of synchrotron radiation is observed, particularly for an electron beam with spins initially aligned parallel to the field.

   hep-phMod.Phys.Lett.A(2026)·0 citations
8. 08*

   The LHC has ruled out Supersymmetry -- really?

   L. Constantin🇫🇷 · S. Kraml🇫🇷 · F. Mahmoudi🇫🇷

   Despite early hopes that the Large Hadron Collider (LHC) would quickly unveil supersymmetric particles, none have been detected to date. This review examines the impact of the LHC results on the viability of weak-scale supersymmetry, and discusses whether the possibility of discovering supersymmetric particles remains within reach.

   hep-phNPB(2025)·15 citations
9. 09*

   Spin effect in vacuum pair production under two-color rotating electric fields

   Zhao-Yuan Chen🇨🇳 · Orkash Amat🇨🇳 · Jin-hui Bai🇨🇳 · Mamat Ali Bake🇨🇳

   We investigated the spin effect on the vacuum pair production by Dirac-Heisenberg-Wigner (DHW) formalism under two-color counter-rotating electric fields. We primarily studied the combined effects of the field asymmetry, time delay, and frequency chirp on the particle momentum spectrum with and without considering the spin effect. We have observed that the vacuum pair production process demonstrates spin dependence even in a pure electric field and is sensitive to variations in the field parameters. The results indicate that the spin-dependent momentum spectrum exhibited distinct outcomes for various asymmetric fields with different chirp values and time delay. For an extended asymmetric field with large chirp and time delay, the particle number density can be increased by more than six orders of magnitude. The spin-up and spin-down particles are approximately comparable for a symmetric field with a small-frequency chirp and are dominated by the spin-up particles for a larger chirp. However, in the case of an asymmetric field, the increase in field asymmetry and the chirp parameter lead to a reversal of the spin asymmetry degree. For a shortened asymmetric electric field with a large-frequency chirp, the number of spin-up particles increases, leading to a spin asymmetry degree of $98.62\%$. Conversely, in an extended asymmetric field, the number of spin-down particles increases significantly, which corresponds to a spin asymmetry degree of $99.94\%$.

   hep-phPRD(2025)·13 citations
10. 10*

    Inferring correlated distributions: boosted top jets

    Ezequiel Alvarez🇦🇷 · Manuel Szewc🇺🇸 · Alejandro Szynkman🇦🇷 · Santiago Tanco🇦🇷 · Tatiana Tarutina🇦🇷

    Improving the understanding of signal and background distributions in signal-region is a valuable key to enhance any analysis in collider physics. This is usually a difficult task because -- among others -- signal and backgrounds are hard to discriminate in signal-region, simulations may reach a limit of reliability if they need to model non-perturbative QCD, and distributions are multi-dimensional and many times may be correlated within each class. Bayesian density estimation is a technique that leverages prior knowledge and data correlations to effectively extract information from data in signal-region. In this work we extend previous works on data-driven mixture models for meaningful unsupervised signal extraction in collider physics to incorporate correlations between features. Using a standard dataset of top and QCD jets, we show how simulators, despite having an expected bias, can be used to inject sufficient inductive nuance into an inference model in terms of priors to then be corrected by data and estimate the true correlated distributions between features within each class. We compare the model with and without correlations to show how the signal extraction is sensitive to their inclusion and we quantify the improvement due to the inclusion of correlations using both supervised and unsupervised metrics.

    hep-phhep-exSciPost Phys.Core(2025)·2 citations
11. 11*

    Anomalies in Hadronic $B$ Decays: an Update

    Bhubanjyoti Bhattacharya🇺🇸 · Marianne Bouchard🇨🇦 · Luke Hudy🇺🇸 · Alexandre Jean🇨🇦 · David London🇨🇦 · Christopher MacKenzie🇺🇸

    Recently, $B\to PP$ decays ($B=\{B^0,B^{+},B_s^0\}$, $P=\{\pi ,K\}$) were analyzed under the assumption of flavor SU(3) symmetry (SU(3)${}_F$). Although the individual fits to $\Delta S=0$ or $\Delta S=1$ decays are good, it was found that the combined fit is very poor: there is a $3.6\sigma$ disagreement with the SU(3)${}_F$ limit of the standard model (SM${}_{{\mathrm{SU}(3)}_{\mathrm{F}}}$). One can remove this discrepancy by adding SU(3)${}_F$-breaking effects, but 1000\% SU(3)${}_F$ breaking is required. In this paper, we extend this analysis to include decays in which there is an $\eta$ and/or ${\eta }^{\prime }$ meson in the final state. We now find that the combined fit exhibits a $4.1\sigma$ discrepancy with the SM${}_{{\mathrm{SU}(3)}_{\mathrm{F}}}$, and 1000\% SU(3)${}_F$-breaking effects are still required to explain the data. These results are rigorous, group-theoretically -- no theoretical assumptions have been made. But when one adds some theoretical input motivated by QCD factorization, the discrepancy with the SM${}_{{\mathrm{SU}(3)}_{\mathrm{F}}}$ grows to $4.9\sigma$.

    hep-phhep-exPRD(2025)·19 citations
12. 12*

    Gauged $\tau$-lepton chiral currents and $B\to K^{(\ast )}{E}_{\mathrm{miss}}$

    Luca Di Luzio🇮🇹 · Marco Nardecchia🇮🇹 · Claudio Toni🇫🇷

    We consider a class of theories with a $U(1{)}_X$ gauge symmetry associated with leptonic chiral currents. The low-energy effective field theory includes a light spin-$1$ boson coupled to the electroweak gauge sector via a Wess-Zumino term, which ensures anomaly cancellation in the infrared. As a concrete application, we show that a light vector boson with mass $m_X\simeq 2.1\text{GeV}$, coupled to a $\tau$-lepton chiral current, can readily account for the recent $3\sigma$ excess observed in $B\to K^{(\ast )}{E}_{\mathrm{miss}}$ at Belle II, while remaining consistent with existing constraints from $Z\to \gamma E_{\mathrm{miss}}$ and direct searches for anomalon fields responsible for anomaly cancellation in the ultraviolet. After classifying phenomenologically viable models, we explore in greater detail two concrete realizations which give rise to distinctive phenomenological signatures, potentially accessible at future experiments at the high-energy and intensity frontiers.

    hep-phPRD(2025)·11 citations
13. 13*

    Suggestions of decreasing dark energy from supernova and BAO data: an update

    Mark Van Raamsdonk🇨🇦 · Chris Waddell🇨🇦

    In a previous work 2305.04946, we found that supernova and baryon acoustic oscillation data support the hypothesis that late time cosmic acceleration is caused by the potential energy of a scalar field descending its potential, as suggested by holographically defined models of quantum gravity. In this note, we update our analysis using the Dark Energy Survey 5 year supernova data set (DES-SN5YR) and the baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument Data Release 2 (DESI DR2). Approximating the scalar potential via a first order Taylor series $V\approx V_0+V_1\varphi$ about the present value, and making use of only recent-time data from DES-SN5YR and DESI DR2, we find that the slope parameter is constrained as $V_1=1.49\pm 0.25$ in a standard likelihood analysis. This is naively a $>5\sigma$ discrepancy with $\Lambda$CDM (which has $V_1=0$), though a more detailed analysis not assuming a Gaussian likelihood distribution suggests $4\sigma$ significance. Based only on the $\Delta {\chi }^2=-13.7$ improvement of fit while ignoring parameter space volumes disfavours $\Lambda$CDM at a $3\sigma$ significance level. These significance measures are substantially improved from our previous analysis using older data sets. We also reproduce the DESI DR2 parameter constraints based on the same combination of data and find that the $\Lambda$CDM is more strongly disfavoured in the context of the linear potential extension (dubbed $V_0{V}_1$) as compared with the $w_0{w}_a$ extension of $\Lambda$CDM. A caveat is that for both $w_0{w}_a$ and $V_0{V}_1$, much of the significance relies on the historical $z<0.1$ supernova samples included in the DES-SN5YR data set.

    ↳ astro-ph.COhep-phhep-th9 citations
14. 14*

    Astrophysical Gamma-ray and Neutrino Production Following from the Physics of Photon-Nucleon Interactions

    Floyd W. Stecker🇺🇸

    The aim of this paper is to present a more complete consideration of the theoretical concepts and experimental aspects of the physics of photoproduction interactions involving nuclei. This treatment is based in large part on the most recent and extensive empirical data on particle photoproduction interactions with protons. The implications of photoproduction involving helium nuclei are also treated and compared with photoproduction involving protons. It is found that photoproduction interactions with helium nuclei produce approximately 10% of the number of pions as compared with photoproduction interactions involving protons in astrophysical sources, assuming the cosmological abundance of He. In addition to the production of pions, we also demonstrate the relative effect of excited nucleon p-pi and p-2pi resonances and rho, eta, omega, and K meson production and decay channels that result in neutrino and gamma-ray production. The production of mesons other than pions is shown not to be significant for calculations of astrophysical gamma-ray and neutrino production. It is further shown that, for astrophysical purposes, the Delta(1232) resonance channel clearly dominates. However, a blend of nucleon resonances at 1400 GeV can contribute as much as 20% to the neutrino flux.

    ↳ astro-ph.HEhep-ph2 citations
15. 15*

    Detector Designs for Frontier Measurements in Neutrino and Collider Physics in the 21st Century

    Wonyong Chung🇺🇸

    The last energy-frontier lepton collider, LEP, established several limits that still hold today. A key one is the counting of three light neutrino species from the invisible decay width of the Z boson. From a collider calorimetry standpoint, the missing energy is an invitation to design an experiment to directly measure the neutrino mass. We present a new type of EM spectrometer which leverages the first adiabatic invariant in magnetic gradient drift to achieve exponentially bounded resolution in a highly compact and scalable format, enabling the PTOLEMY experiment to not only measure the neutrino mass at the tritium endpoint, but one day directly detect the Cosmic Neutrino Background. Meanwhile, the next lepton collider promises to expose the Higgs self-coupling and complete the accounting of lepton universality. We present a dual-readout, segmented crystal calorimeter for future collider detectors, combining new hardware capabilities with novel AI/ML reconstruction techniques towards realizing a detector that must definitively and unambiguously surpass its predecessors. Together, these studies confront the most pressing challenges for 21st century particle physics experiments to achieve the sensitivities needed to bridge the gap between the largest and smallest scales of reality.

    ↳ physics.ins-dethep-exhep-ph0 citations
16. 16*

    Improved Holographic QCD on a Curved Background: an Application of Dynamical System Theory in Holography

    Elias Kiritsis🇫🇷 · Francesco Nitti🇫🇷 · Jean-Loup Raymond🇫🇷

    The finite-curvature phase diagram of IHQCD, a bottom-up holographic model for large $N_c$ non-supersymmetric YM${}_4$, is investigated. This holographic theory belongs to a class of Einstein-Dilaton theories that exhibit no scaling in the IR. We use advanced techniques from dynamical system theory to address this problem that is harder than other holographic setups. We classify all solutions where the dual theory is defined on a constant curvature manifold, both with positive and negative curvature. For general theories in this class a quantum phase transition occurs at finite curvature. For IHQCD in particular, we find that the phase transition occurs at zero curvature.

    ↳ hep-thhep-phFortsch.Phys.(2025)·7 citations
17. 17*

    Graviton-photon conversion in stochastic magnetic fields

    Wataru Chiba🇯🇵 · Ryusuke Jinno🇯🇵 · Kimihiro Nomura🇯🇵

    We study graviton-photon conversion in the presence of stochastic magnetic fields. Assuming Gaussian magnetic fields that may possess nontrivial helicity, and unpolarized gravitational waves (GWs) as the initial state, we obtain expressions for the intensity and linear/circular polarizations of GWs after propagation over a finite distance. We calculate both the expectation values and variances of these observables, and find their nontrivial dependence on the typical correlation length of the magnetic field, the propagation distance, and the photon plasma mass. Our analysis reveals that an observationally favorable frequency range with narrower variance can emerge for the intensity, while a peak structure appears in the expectation value of the circular polarization when the magnetic field has nonzero helicity. We also identify a consistency relation between the GW intensity and circular polarization.

    ↳ gr-qcastro-ph.COhep-phPRD(2025)·5 citations
18. 18*

    Generalized Parton Distributions from Lattice QCD with Asymmetric Momentum Transfer: Tensor Case

    Shohini Bhattacharya🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Andreas Metz🇺🇸 · Joshua Miller🇺🇸 · Peter Petreczky🇺🇸 · Fernanda Steffens🇩🇪

    The calculation of generalized parton distributions (GPDs) in lattice QCD was traditionally done by calculating matrix elements in the symmetric frame. Recent advancements have significantly reduced computational costs by calculating these matrix elements in the asymmetric frame, allowing us to choose the momentum transfer to be in either the initial or final states only. The theoretical methodology requires a new parametrization of the matrix element to obtain Lorentz-invariant amplitudes, which are then related to the GPDs. The formulation and implementation of this approach have already been established for the unpolarized and helicity GPDs. Building upon this idea, we extend this formulation to the four leading-twist quark transversity GPDs ($H_T$, $E_T$, ${\tilde{H}}_T$, ${\tilde{E}}_T$). We also present numerical results for zero skewness using an $N_f=2+1+1$ ensemble of twisted mass fermions with a clover improvement. The light quark masses employed in these calculations correspond to a pion mass of about 260 MeV. Furthermore, we include a comparison between the symmetric and asymmetric frame calculations to demonstrate frame independence of the Lorentz-invariant amplitudes. Analysis of the matrix elements in the asymmetric frame is performed at several values of the momentum transfer squared, $-t$, ranging from 0.17 GeV${}^2$ to 2.29 GeV${}^2$.

    ↳ hep-lathep-exhep-phhep-thPRD(2025)·14 citations
19. 19*

    Thermal Static Potential and Pseudo-Scalar Quarkonium Spectral Functions from 2+1 Flavor Lattice QCD

    Sajid Ali🇩🇪 · Dibyendu Bala🇩🇪 · Olaf Kaczmarek🇩🇪 · Pavan🇩🇪

    Quarkonia, which are bound states of a heavy quark and antiquark, play a key role in probing the quark-gluon plasma (QGP). The dynamics of quarkonia in the QGP are encoded in their finite-temperature spectral functions. In this work, we estimate the quarkonium spectral functions in the pseudo-scalar channel using 2+1 flavor lattice QCD with a pion mass of $320\text{MeV}$, at temperatures of $220\text{MeV}(1.2T_{pc}),251\text{MeV}(1.4T_{pc})\text{and}293\text{MeV}(1.6T_{pc})$. Reconstructing the spectral function from the Euclidean lattice correlator is a well-known ill-posed problem, requiring additional physics-motivated input. We address this by smoothly matching contributions from different frequency regions of the spectral function, using appropriate physics valid for each region. The spectral function around $\omega \sim 2M_q$ is obtained using a non-perturbative complex potential, while for $\omega \gg 2M_q$ it is modeled using results from vacuum perturbation theory. Since the pseudoscalar channel does not receive a transport contribution near $\omega \sim 0$, we find that the combination of these two regions already provides a good description of the relativistic lattice pseudoscalar correlator. We observe a substantial thermal width in the ${\eta }_c(1S)$ state, indicating that pseudoscalar charmonium (${\eta }_c$) is nearing dissolution at the studied temperatures. In comparison, the ${\eta }_b$ ground state exhibits little change and remains well-defined.

    ↳ hep-lathep-exhep-phhep-th+1PRD(2025)·14 citations
20. 20*

    Truly Confining Supersymmetric Gauge Theories

    Riku Ishikawa🇯🇵 · Hitoshi Murayama🇺🇸 · Shota Saito🇯🇵

    We classify ``truly confining'' (t-confining) supersymmetric gauge theories, in which no center charges can be screened, and Wilson loops in the fundamental representation are therefore expected to exhibit an area law. In all cases, we identify the condensation of certain ``magnetic'' operators. Many of them have more than three branches, and one with vanishing superpotential, a phenomenon not previously observed.

    ↳ hep-thhep-ph2 citations
21. 21*

    Weakly-Coupled Trace Anomaly Action for Gravity

    Gregory Gabadadze🇺🇸 · Giorgi Tukhashvili🇺🇸

    We discuss a local, diff-invariant quantum effective action for gravity that captures the trace anomaly via a counter-term. We discuss why this counter-term is the most significant among infinitely many possible ones, and show how the counter-term leads to a scattering amplitude that is strongly coupled at arbitrarily low energies. We show how the introduction of a new sector with spontaneously broken scale invariance removes the strong coupling problem, and discuss some physical consequences due to the new sector. Three Appendices summarize quantum effective actions -- highlighting connections between their local, and seemingly non-local formulations -- for the scale anomaly in 4D QED, for the axial anomaly in 2D QED, and for the scale anomaly in a 2D sigma model.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.A(2025)·1 citation
22. 22*

    Flavor Equilibration of Supernova Neutrinos: Exploring the Dynamics of Slow Modes

    Ian Padilla-Gay🇺🇸 · Heng-Hao Chen🇹🇼 · Sajad Abbar🇩🇪 · Meng-Ru Wu🇹🇼 · Zewei Xiong🇩🇪

    Neutrinos experience collective flavor conversion in extreme astrophysical environments such as core-collapse supernovae (CCSNe). One manifestation of collective conversion is slow flavor conversion (SFC), which has recently attracted renewed interest owing to its ubiquity across different regions of the supernova environment. In this study, we systematically examine the evolution of kinematic decoherence in a dense neutrino gas undergoing SFC, considering lepton number asymmetries as large as $30\%$. Our findings show that the neutrino gas asymptotically evolves toward a generic state of coarse-grained flavor equilibration which is constrained by approximate lepton number conservation. The equilibration occurs within a few factors of the inverse vacuum oscillation frequency, ${\omega }^{-1}$, which corresponds to (anti)neutrinos reaching near flavor equipartition after a few kilometers for typical supernova neutrino energies. Notably, the quasi-steady state of the neutrino number densities can be quantitatively described by the neutrino-antineutrino number density ratio $n_{{\bar{\nu }}_e}/n_{{\nu }_e}$ alone. Such a simple estimation opens new opportunities for incorporating SFC into CCSN simulations, particularly in regions where SFC develops on scales much shorter than those of collisions.

    ↳ astro-ph.HEhep-phPRD(2025)·20 citations
23. 23*

    The Prospect from the Upcoming CMB Experiment LiteBIRD to Discover Axion-like Particles Using Milky Way

    Harsh Mehta🇮🇳 · Suvodip Mukherjee🇮🇳

    The existence of axion-like particles (ALPs) can be probed from their signatures in the Cosmic Microwave Background (CMB) due to the photon-ALP resonant conversion over the mass range of ALPs that matches with the effective mass of photons in the plasma in the astrophysical systems. Such a conversion can also occur in the Milky Way halo and disk and can cause a unique spatial and spectral distortion. The signal is highly non-Gaussian and cannot be measured precisely by the usual power-spectrum approach. We devise a new technique to search for this signal from the upcoming full-sky CMB experiment LiteBIRD using its multi-frequency band using a template-based spatial profile of the ALP distortion signal. This technique captures the large-scale non-Gaussian aspects of the ALP distortion signal in terms of a spatial template and makes it possible to search for any non-zero ALP signal. We show that the inference of the ALP coupling using the template-based technique from LiteBIRD can provide constraints on the coupling constant approximately $g_{a\gamma }<6.5\times 10^{-12}{\mathrm{GeV}}^{-1}$ for ALP masses below $10^{-14}$ eV at 95\% confidence interval which is an order of magnitude better than the current bounds from CERN Axion Solar Telescope (CAST) at $g_{a\gamma }<6.6\times 10^{-11}{\mathrm{GeV}}^{-1}$, This shows the capability of future multi-band CMB experiment LiteBIRD in opening the discovery space towards physics beyond the standard model.

    ↳ astro-ph.COastro-ph.GAastro-ph.HEhep-phJCAP(2025)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.