Mon·Mar 11, 2024Monday·March 11, 2024

1. 01*

   Dark Matter Line Searches with the Cherenkov Telescope Array

   S. Abe🇯🇵 · J. Abhir🇨🇭 · A. Abhishek🇮🇹 · F. Acero🇫🇷 · A. Acharyya🇺🇸 · R. Adam🇫🇷 · A. Aguasca-Cabot🇪🇸 · I. Agudo🇪🇸 · A. Aguirre-Santaella🇬🇧 · J. Alfaro🇨🇱 · R. Alfaro🇲🇽 · N. Alvarez-Crespo🇪🇸 and 553 other authors

   Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of selected dwarf spheroidal galaxies. We find that current limits and detection prospects for dark matter masses above 300 GeV will be significantly improved, by up to an order of magnitude in the multi-TeV range. This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing on regions with large dark matter densities. Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g.~box-shaped spectra, that would likewise very clearly point to a particle dark matter origin.

   hep-phastro-ph.HEhep-exJCAP(2024)·52 citations
2. 02*

   Reappraisal of SU(3)-flavor breaking in $B\to DP$

   Jonathan Davies🇬🇧 · Stefan Schacht🇬🇧 · Nicola Skidmore🇬🇧 · Amarjit Soni🇺🇸

   In light of recently found deviations of the experimental data from predictions from QCD factorization for $B_{(s)}\to D_{(s)}P$ decays, where $P=\{\pi ,K\}$, we systematically probe the current status of the SU(3)${}_F$ expansion from a fit to experimental branching ratio data without any further theory input. We find that the current data are in agreement with the power counting of the SU(3)${}_F$ expansion. While the SU(3)${}_F$ limit is excluded at $>5\sigma$, amplitude-level SU(3)${}_F$-breaking contributions of $\sim 20\%$ suffice for an excellent description of the data. SU(3)${}_F$ breaking is needed in tree ($>5\sigma$) and color-suppressed tree ($2.4\sigma$) diagrams. We are not yet sensitive to SU(3)${}_F$ breaking in exchange diagrams. From the underlying SU(3)${}_F$ parametrization we predict the unmeasured branching ratios $\mathcal{B}({\overline{B}}_s^0\to {\pi }^{-}{D}^{+})=2\mathcal{B}({\overline{B}}_s^0\to {\pi }^0{D}^0)=[0.3,7.2]\times 10^{-6}$ of suppressed decays that can be searched for at the LHCb experiment.

   hep-phhep-exPRD(2024)·8 citations
3. 03*

   Information divergences to parametrize astrophysical uncertainties in dark matter direct detection

   Gonzalo Herrera🇺🇸 · Andreas Rappelt🇩🇪

   Astrophysical uncertainties in dark matter direct detection experiments are typically addressed by parametrizing the velocity distribution in terms of a few uncertain parameters that vary around some central values. Here we propose a method to optimize over all velocity distributions lying within a given distance measure from a central distribution. We discretize the dark matter velocity distribution as a superposition of streams, and use a variety of information divergences to parametrize its uncertainties. With this, we bracket the limits on the dark matter-nucleon and dark matter-electron scattering cross sections, when the true dark matter velocity distribution deviates from the commonly assumed Maxwell-Boltzmann form. The methodology pursued is general and could be applied to other physics scenarios where a given physical observable depends on a function that is uncertain.

   hep-phastro-ph.COhep-exPRD(2025)·6 citations
4. 04*

   Heavy quarkonium spectral function in an anisotropic background

   Wen-Bin Chang🇨🇳 · De-fu Hou🇨🇳

   In this paper, we use a five-dimensional Einstein-dilaton-two-Maxwell holographic QCD model to investigate the dissociation effects of $J/\Psi$ and ${\rm Y}(1S)$ states in an anisotropic medium by calculating their spectral functions. First, we present the holographic quarkonium masses at zero temperature via Physics-Informed Neural Networks. Then, at finite temperature, we derive the spectral functions, representing heavy vector mesons as peaks, and observe that with increasing anisotropy, temperature, chemical potential, and warp factor, the peak height diminishes while its width expands, indicating an accelerated dissociation process. Additionally, the results indicate the anisotropy induces a stronger dissociation effect in the direction parallel to the polarization compared to the perpendicular, revealing the anisotropy's directional influence.

   hep-phPRD(2024)·16 citations
5. 05*

   Constraints on evaporating primordial black holes from the AMS-02 positron data

   Jia-Zhi Huang🇨🇳 · Yu-Feng Zhou🇨🇳

   Cosmic-ray (CR) positrons are relatively rare due to their secondary origin and thus sensitive to exotic contributions. Primordial black holes (PBHs) with masses above $\sim 5\times 10^{14}\mathrm{g}$ can be stable sources of CR positrons due to Hawking radiation. The energies of the evaporated positrons can increase significantly through scattering with the Galactic random magnetic fields during the propagation in the Galaxy, which is a generic feature in diffusive re-acceleration CR propagation models. We show that in well-constrained diffusive re-acceleration models, a significant portion of CR positron flux can enter the energy region of $\mathcal{O}(\text{GeV})$, and can be constrained by the current AMS-02 data. As an example, we show that in the Galprop+Helmod model for CR propagation in the Galaxy and heliosphere, an upper limit of $f_{\text{PBH}}\lesssim 2.15\times 10^{-4}$ at PBH mass $2\times 10^{16}$~g can be obtained, which improve the previous constraints from the Voyager CR all-electron data by around an order of magnitude.

   hep-phPRD(2025)·16 citations
6. 06*

   Jet Discrimination with Quantum Complete Graph Neural Network

   Yi-An Chen🇹🇼 · Kai-Feng Chen🇹🇼

   Machine learning, particularly deep neural networks, has been widely used in high-energy physics, demonstrating remarkable results in various applications. Furthermore, the extension of machine learning to quantum computers has given rise to the emerging field of quantum machine learning. In this paper, we propose the Quantum Complete Graph Neural Network (QCGNN), which is a variational quantum algorithm based model designed for learning on complete graphs. QCGNN with deep parametrized operators offers a polynomial speedup over its classical and quantum counterparts, leveraging the property of quantum parallelism. We investigate the application of QCGNN with the challenging task of jet discrimination, where the jets are represented as complete graphs. Additionally, we conduct a comparative analysis with classical models to establish a performance benchmark.

   hep-phcs.LGquant-phPRD(2025)·14 citations
7. 07*

   Decay-angular-distribution correlated $CP$ violation in heavy hadron cascade decays

   Yu-Jie Zhao🇨🇳 · Zhen-Hua Zhang🇨🇳 · Xin-Heng Guo🇨🇳

   $CP$ violation in baryon decay processes is still undiscovered to date. We present a general analysis of the decay-angular-distributions and the corresponding $CP$ asymmetries in cascade decays of the type $\mathbb{H}\to R(\to ab)c$, where $\mathbb{H}$ is a heavy hadron that decays through weak interactions $\mathbb{H}\to Rc$, and the resonance $R$ decays strongly via $R\to ab$. Based on the analysis, we propose to search for $CP$ violation in the decay-angular-distributions in the cascade decay processes $\mathbb{B}\to \mathcal{B}M$, with $\mathcal{B}$ or $M$ subsequently decaying through strong interactions, where $\mathbb{B}$ is the mother baryon, $\mathcal{B}$ or $M$ are the daughter baryon and meson, respectively, and $M$ has to be spin-nonzero. We also present some typical decay channels in which the search for such kinds of $CP$ asymmetries can be performed.

   hep-phPRD(2024)·5 citations
8. 08*

   Phenomenological model for $\gamma {\gamma }^{\ast }\to K{\bar{K}}^{\ast }(892)$ constraining the $f_1(1420)$ transition form factor

   Xiu-Lei Ren🇩🇪 · Igor Danilkin🇩🇪 · Marc Vanderhaeghen🇩🇪

   We present a phenomenological study of the $\gamma {\gamma }^{\ast }\to K{\bar{K}}^{\ast }(892)$ process by including the $s$-channel production of the $\eta (1475)$ and $f_1(1420)$ resonances. The non-resonant channel via $K$- and $K^{\ast }$-exchanges is investigated carefully by performing the Lorentz tensor decomposition and is constructed to yield a correct high-energy Regge behavior. The transition form factor of $f_1(1420)$ is adjusted to achieve a reasonable description of the existing L3 data in the $f_1(1420)$ resonance region. This model is intended to serve as a Monte Carlo generator for the analysis currently being performed by the BESIII Collaboration. We also estimate the polarized $\gamma {\gamma }^{\ast }\to K{\bar{K}}^{\ast }(892)$ cross sections and demonstrate how to extract the transition form factors of $f_1(1420)$ from the polarized cross sections.

   hep-phnucl-thPRD(2024)·1 citation
9. 09*

   Effects of gravitational particle production on Higgs portal dark matter

   Soichiro Izumine🇯🇵 · Kazunori Nakayama🇯🇵

   The gravitational interaction is ubiquitous and the effect of gravitational particle production necessarily contributes to the dark matter abundance. A simple candidate of dark matter is a scalar particle, whose only renormalizable interaction is the Higgs portal coupling. We show that the abundance of Higgs portal dark matter is significantly affected by the gravitational production effect. In particular, the gravitational production from the coherently oscillating inflaton field during the reheating often gives dominant contribution.

   hep-phJCAP(2024)·1 citation
10. 10*

    The minimal cosmological standard model

    Gabriela Barenboim🇪🇸 · P. Ko🇰🇷 · Wan-il Park🇰🇷

    We propose a novel minimal scenario which simultaneously addresses the following theoretical/cosmological/phenomenological puzzles: (i) the origin of scales, (ii) primordial inflation, (iii) matter-antimatter asymmetry, (iv) tiny neutrino masses, (v) dark matter, and (vi) the strong CP-problem. Exact scale-symmetry was assumed. A global $U(1{)}_{\mathrm{PQ}}$-symmetry was also assumed but only in the matter sector. The novelty of the scenario is the introduction of an explicit $U(1{)}_{\mathrm{PQ}}$-breaking term in the gravity sector only. Such a term does not disturb the axion solution whereas naturally realizes an axi-majoron hybrid inflation which allows a natural realization of Affleck-Dine mechanism for generating Peccei-Quinn number asymmetry. The asymmetry can be transferred to the visible sector via the right-handed neutrino portal through non-thermal decay and thermal processes, even without the presence of a CP-violating phase in the matter sector. Dark matter and dark radiation are obtained by cold and hot components of axi-majorons, respectively.

    hep-phgr-qcNPB(2025)·6 citations
11. 11*

    Particle shells from relativistic bubble walls

    Iason Baldes🇫🇷 · Maximilian Dichtl🇫🇷 · Yann Gouttenoire🇮🇱 · Filippo Sala🇮🇹

    Relativistic bubble walls from cosmological phase transitions (PT) necessarily accumulate expanding shells of particles. We systematically characterize shell properties, and identify and calculate the processes that prevent them from free streaming: phase-space saturation effects, out-of-equilibrium $2\to 2$ and $3\to 2$ shell-shell and shell-bath interactions, and shell interactions with bubble walls. We find that shells do not free stream in scenarios widely studied in the literature, where standard predictions will need to be reevaluated, including those of bubble wall velocities, gravitational waves (GW) and particle production. Our results support the use of bulk-flow GW predictions in all regions where shells free stream, irrespectively of whether or not the latent heat is mostly converted in the scalar field gradient.

    hep-phastro-ph.COastro-ph.HEgr-qcJHEP(2024)·21 citations
12. 12*

    OmniJet-$\alpha$: The first cross-task foundation model for particle physics

    Joschka Birk🇩🇪 · Anna Hallin🇩🇪 · Gregor Kasieczka🇩🇪

    Foundation models are multi-dataset and multi-task machine learning methods that once pre-trained can be fine-tuned for a large variety of downstream applications. The successful development of such general-purpose models for physics data would be a major breakthrough as they could improve the achievable physics performance while at the same time drastically reduce the required amount of training time and data. We report significant progress on this challenge on several fronts. First, a comprehensive set of evaluation methods is introduced to judge the quality of an encoding from physics data into a representation suitable for the autoregressive generation of particle jets with transformer architectures (the common backbone of foundation models). These measures motivate the choice of a higher-fidelity tokenization compared to previous works. Finally, we demonstrate transfer learning between an unsupervised problem (jet generation) and a classic supervised task (jet tagging) with our new OmniJet-$\alpha$ model. This is the first successful transfer between two different and actively studied classes of tasks and constitutes a major step in the building of foundation models for particle physics.

    hep-phcs.LGhep-exphysics.data-anMach.Learn.Sci.Tech.(2024)·89 citations
13. 13*

    Thermal production of astrophobic axions

    Marcin Badziak🇵🇱 · Keisuke Harigaya🇺🇸 · Michał Łukawski🇵🇱 · Robert Ziegler🇩🇪

    Hot axions are produced in the early Universe via their interactions with Standard Model particles, contributing to dark radiation commonly parameterized as $\Delta N_{\text{eff}}$. In standard QCD axion benchmark models, this contribution to $\Delta N_{\text{eff}}$ is negligible after taking into account astrophysical limits such as the SN1987A bound. We therefore compute the axion contribution to $\Delta N_{\text{eff}}$ in so-called astrophobic axion models characterized by strongly suppressed axion couplings to nucleons and electrons, in which astrophysical constraints are relaxed and $\Delta N_{\text{eff}}$ may be sizable. We also construct new astrophobic models in which axion couplings to photons and/or muons are suppressed as well, allowing for axion masses as large as few eV. Most astrophobic models are within the reach of CMB-S4, while some allow for $\Delta N_{\text{eff}}$ as large as the current upper bound from Planck and thus will be probed by the Simons Observatory. The majority of astrophobic axion models predicting large $\Delta N_{\text{eff}}$ is also within the reach of IAXO or even BabyIAXO.

    hep-phJHEP(2024)·29 citations
14. 14*

    Impact of Dark Sector Preheating on CMB Observables

    Marcos A. G. Garcia🇲🇽 · Aline Pereyra-Flores🇲🇽

    The prediction of a nearly scale-invariant spectrum of curvature and tensor fluctuations is among the main features of cosmic inflation. The current measurements of the primordial fluctuations in the cosmic microwave background (CMB) provide tight constraints on the amplitude of the scalar and tensor spectra, and the scalar tilt. However, the precise connection between these observables and a given inflationary model, depends on the expansion history between the end of inflation and the beginning of the radiation dominated era, which corresponds to the reheating epoch. This mapping between horizon exit and reentry of fluctuations, parametrized by the number of $e$-folds $N_{\ast }$, can therefore be affected by the presence of a transient epoch of non-perturbative particle production during reheating ({\em preheating}). Using a combination of perturbative and lattice computations, we quantify the impact of preheating in a non-equilibrated dark matter sector on the CMB observables, under the assumption of a simultaneous perturbative decay of the inflaton into Standard Model particles. Combined with structure formation constraints, this allows us to impose stringent bounds on the post-inflationary reheating temperature.

    ↳ astro-ph.COhep-phJCAP(2024)·4 citations
15. 15*

    Local-in-time Conservative Binary Dynamics at Fourth Post-Minkowskian Order

    Christoph Dlapa🇩🇪 · Gregor Kälin🇩🇪 · Zhengwen Liu🇩🇰 · Rafael A. Porto🇩🇪

    Leveraging scattering information to describe binary systems in generic orbits requires identifying local- and nonlocal-in-time tail effects. We report here the derivation of the universal (non-spinning) local-in-time conservative dynamics at fourth Post-Minkowskian order, i.e. $\mathcal{O}(G^4)$. This is achieved by computing the nonlocal-in-time contribution to the deflection angle, and removing it from the full conservative value in [2112.11296,2210.05541]. Unlike the total result, the integration problem involves two scales, velocity and mass ratio, and features multiple polylogarithms, complete elliptic and iterated elliptic integrals, notably in the mass ratio. We reconstruct the local radial action, center-of-mass momentum and Hamiltonian, as well as the exact logarithmic-dependent part(s), all valid for generic orbits. We incorporate the remaining nonlocal terms for elliptic-like motion to sixth Post-Newtonian order. The combined Hamiltonian is in perfect agreement in the overlap with the Post-Newtonian state of the art. The results presented here provide the most accurate description of gravitationally-bound binaries harnessing scattering data to date, readily applicable to waveform modelling.

    ↳ hep-thgr-qchep-phPRL(2024)·74 citations
16. 16*

    Constraints on Metastable Dark Energy Decaying into Dark Matter

    J.S.T. de Souza🇧🇷 · G.S. Vicente🇧🇷 · L.L.Graef🇧🇷

    We revisit the proposal that an energy transfer from dark energy into dark matter can be described in field theory by a first order phase transition. We analyze the model proposed in Ref. Abdalla et al. (2013), using updated constraints on the decay time of a metastable dark energy from the work of Ref. Shafieloo et al. (2018). The results of our analysis show no prospects for potentially observable signals that could distinguish this scenario. We also show that such model would not drive a complete transition to a dark matter dominated phase even in a distant future. Nevertheless, the model is not excluded by the latest data and we confirm that the mass of the dark matter particle that would result from such a process corresponds to an axion-like particle, which is currently one of the best motivated dark matter candidates. We argue that extensions to this model, possibly with additional couplings, still deserve further attention as it could provide an interesting and viable description for an interacting dark sector scenario based in a single scalar field.

    ↳ astro-ph.COhep-phUniverse(2024)·4 citations
17. 17*

    Constraining primordial black holes as dark matter using AMS-02 data

    Bing-Yu Su🇨🇳 · Xu Pan🇨🇳 · Guan-Sen Wang🇨🇳 · Lei Zu🇨🇳 · Yupeng Yang🇨🇳 · Lei Feng🇨🇳

    Primordial black holes (PBHs) are the plausible candidates for the cosmological dark matter. Theoretically, PBHs with masses $M_{\mathrm{PBH}}$ in the range of $4\times 10^{14}\sim 10^{17}\mathrm{g}$ can emit sub-GeV electrons and positrons through Hawking radiation. Some of these particles could undergo diffusive reacceleration during propagation in the Milky Way, potentially reaching energies up to the GeV level observed by AMS-02. In this work, we utilize AMS-02 data to constrain the PBH abundance $f_{\mathrm{PBH}}$ by employing the reacceleration mechanism. Under the assumption of a monochromatic PBH mass distribution, our findings reveal that the limit is stricter than that derived from Voyager 1 data. This difference is particularly pronounced when $M_{\mathrm{PBH}}\lesssim 10^{15}\mathrm{g}$, exceeding an order of magnitude. The constraints are even more robust in a more realistic scenario involving a log-normal mass distribution of PBHs. Moreover, we explore the impact of varying propagation parameters and solar modulation potential within reasonable ranges, and find that such variations have minimal effects on the final results.

    ↳ astro-ph.HEastro-ph.COhep-phEPJC(2024)·21 citations
18. 18*

    Electrical conductivity and shear viscosity of a pion gas in a thermo-magnetic medium

    Pallavi Kalikotay🇧🇩 · Snigdha Ghosh🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Pradip Roy🇮🇳 · Sourav Sarkar🇮🇳

    We evaluate the electrical conductivity and shear viscosity of a interacting pion gas in a thermo-magnetic medium using the kinetic theory. The collision term of the relativistic Boltzmann transport equation in presence of background magnetic field is solved using the relaxation time approximation. The medium modified relaxation time is obtained from the corresponding in-medium $\pi \pi \to \pi \pi$ scattering cross-section calculated using the thermo-magnetic $\rho$ propagator. It is observed that the average relaxation time shows a $1/T^4$ variation with temperature for a fixed value of magnetic field. The relaxation time shows a mild oscillatory variation with respect to the magnetic field. It is also observed that the medium dependent scattering cross-section causes a considerable amount of influence on the electrical conductivity and shear viscosity compared to its vacuum counterpart.

    ↳ nucl-thhep-phEPJA(2024)·4 citations
19. 19*

    A Goldstone Boson Equivalence for Inflation

    Daniel Green🇺🇸 · Kshitij Gupta🇺🇸 · Yiwen Huang🇺🇸

    The effective field theory of single-field inflation characterizes the inflationary epoch in terms of a pattern of symmetry breaking. An operator acquires a time-dependent vacuum expectation value, defining a preferred spatial slicing. In the absence of dynamical gravity, the fluctuations around the time-dependent background are described by the Goldstone boson associated with this symmetry breaking process. With gravity, the Goldstone is eaten by the metric, becoming the scalar metric fluctuation. In this paper, we will show that in general single-field inflation, the statistics of scalar metric fluctuations are given by the statistics of this Goldstone boson decoupled from gravity up to corrections that are controlled as an expansion in slow-roll parameters. This even holds in the presence of additional parameters, like the speed of sound, that naively enhance the impact of the gravitational terms. In the process, we derive expressions for leading and sub-leading gravitational corrections to all-orders in the Goldstone boson.

    ↳ hep-thastro-ph.COhep-phJHEP(2024)·10 citations
20. 20*

    Proton Helicity GPDs from Lattice QCD

    Joshua Miller🇺🇸 · Shohini Bhattacharya🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Xiang Gao🇺🇸 · Andreas Metz🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Fernanda Steffens🇩🇪 · Yong Zhao🇺🇸

    First lattice QCD calculations of $x$-dependent GPD have been performed in the (symmetric) Breit frame, where the momentum transfer is evenly divided between the initial and final hadron states. However, employing the asymmetric frame, we are able to obtain proton GPDs for multiple momentum transfers in a computationally efficient setup. In these proceedings, we focus on the helicity twist-2 GPD at zero skewness that gives access to the $\tilde{H}$ GPD. We will cover the implementation of the asymmetric frame, its comparison to the Breit frame, and the dependence of the GPD on the squared four-momentum transfer, $-t$. The calculation is performed on an $N_f=2+1+1$ ensemble of twisted mass fermions with a clover improvement. The mass of the pion for this ensemble is roughly 260 MeV.

    ↳ hep-lathep-phhep-thPoS(2024)·2 citations
21. 21*

    Neutrino fluxes from different classes of galactic sources

    Silvia Gagliardini🇮🇱 · Aurora Langella🇮🇹 · Dafne Guetta🇮🇱 · Antonio Capone🇮🇱

    We estimate the neutrino flux from different kinds of galactic sources and compare it with the recently diffuse neutrino flux detected by IceCube. We find that the flux from these sources may contribute to ~ 20% of the IceCube neutrino flux. Most of the sources selected in this work populate the southern hemisphere, therefore a detector like KM3NeT could help in resolving the sources out of the observed diffused galactic neutrino flux.

    ↳ astro-ph.HEhep-phApJ(2024)·15 citations
22. 22*

    Inclusive hadronic decay rate of the $\tau$ lepton from lattice QCD: the $\bar{u}s$ flavour channel and the Cabibbo angle

    C. Alexandrou🇨🇾 · S. Bacchio🇨🇾 · A. De Santis🇮🇹 · A. Evangelista🇮🇹 · J. Finkenrath🇩🇪 · R. Frezzotti🇮🇹 · G. Gagliardi🇮🇹 · M. Garofalo🇩🇪 · B. Kostrzewa🇩🇪 · V. Lubicz🇮🇹 · S. Romiti🇩🇪 · F. Sanfilippo🇮🇹 and 4 other authors

    We present a lattice determination of the inclusive decay rate of the process $\tau \mapsto X_{us}{\nu }_{\tau }$ in which the $\tau$ lepton decays into a generic hadronic state $X_{us}$ with $\bar{u}s$ flavour quantum numbers. Our results have been obtained in $n_f=2+1+1$ iso-symmetric QCD with full non-perturbative accuracy, without any OPE approximation and, except for the presently missing long-distance isospin-breaking corrections, include a solid estimate of all sources of theoretical uncertainties. This has been possible by using the Hansen-Lupo-Tantalo method [1] that we have already successfully applied in [2] to compute the inclusive decay rate of the process $\tau \mapsto X_{ud}{\nu }_{\tau }$ in the $\bar{u}d$ flavour channel. By combining our first-principles theoretical results with the presently-available experimental data we extract the CKM matrix element $|V_{us}|$, the Cabibbo angle, with a $0.9$\% accuracy, dominated by the experimental error.

    ↳ hep-lathep-phPRL(2024)·54 citations
23. 23*

    Confronting the Lippmann-Schwinger equation and the $N/D$ method for coupled-wave separable potentials

    M.S. Sánchez🇪🇸 · J.A. Oller🇪🇸 · D.R. Entem🇪🇸

    We study a family of separable potentials with and without added contact interactions by solving the associated Lippmann-Schwinger equation with two coupled partial waves. The matching of the resulting amplitude matrix with the effective-range expansion is studied in detail. When a counterterm is included in the potential we also carefully discuss its renormalization. Next, we use the matrix $N/D$ method and study whether the amplitude matrices from the potentials considered admit an $N/D$ representation in matrix form. As a novel result we show that it is typically not possible to find such matrix representation for the coupled partial-wave case. However, a separate $N/D$ representation for each coupled partial wave, a valid option known in the literature, is explicitly implemented and numerically solved in cases where the matrix $N/D$ method is unavailable.

    ↳ nucl-thhep-phAnnals Phys.(2024)·1 citation
24. 24*

    Strong constraints on a simple self-interacting neutrino cosmology

    David Camarena🇺🇸 · Francis-Yan Cyr-Racine🇺🇸

    Some cosmic microwave background (CMB) data allow a cosmological scenario in which the free streaming of neutrinos is delayed until close to matter-radiation equality. Interestingly, recent analyses have revealed that large-scale structure (LSS) data also align with this scenario, discarding the possibility of an accidental feature in the CMB sky and calling for further investigation into the free-streaming nature of neutrinos. By assuming a simple representation of self-interacting neutrinos, we investigate whether this nonstandard scenario can accommodate a consistent cosmology for both the CMB power spectra and the large-scale distribution of galaxies simultaneously. Employing three different approaches - a profile likelihood exploration, a nested sampling method, and a heuristic Metropolis-Hasting approximation - we exhaustively explore the parameter space and demonstrate that galaxy data exacerbates the challenge already posed by the Planck polarization data for this nonstandard scenario. We find that the Bayes factor disfavor strong interactions among neutrinos over the $\Lambda$CDM and $\Lambda$CDM + $N_{\mathrm{eff}}$ + $\sum m_{\nu }$ models with odds of $7:10000$ and $23:1000$, respectively, providing large evidence against the simple self-interacting neutrino model. Our analysis emphasizes the need to consider a broader range of phenomenologies in the early Universe. We also highlight significant numerical and theoretical challenges ahead in uncovering the exact nature of the feature observed in the data or, ultimately, confirming the standard chronological evolution of the Universe.

    ↳ astro-ph.COhep-phPRD(2025)·38 citations
25. 25*

    Search for anti-quark nuggets via their interaction with the LHC beam

    K. Zioutas🇬🇷 · A. Zhitnitsky🇨🇦 · C. Zamantzas🇨🇭 · Y. K. Semertzidis🇰🇷 · O. M. Ruimi🇮🇱 · K. Ozbozduman🇹🇷 · M. Maroudas🇩🇪 · A. Kryemadhi🇺🇸 · M. Karuza🇭🇷 · D. Horns🇩🇪 · A. Gougas🇬🇷 · S. Cetin🇹🇷 · G. Cantatore🇮🇹 · D. Budker🇩🇪

    Anti-quark nuggets (AQNs) have been suggested to solve the dark matter (DM) and the missing antimatter problem in the universe and have been proposed as an explanation of various observations. Their size is in the {\mu}m range and their density is about equal to the nuclear density with an expected flux of about $0.4/k{m}^2/year$. For the typical velocity of DM constituents ($\sim$250 km/s), the solar system bodies act as highly performing gravitational lenses. Here we assume that DM streams or clusters are impinging, e.g., on the Earth, as it was worked out for DM axions and Weakly Interacting Massive Particles (WIMPs). Interestingly, in the LHC beam, unforeseen beam losses are triggered by so-called Unidentified Falling Objects (UFOs), which are believed to be constituted of dust particles with a size in the {\mu}m range and a density of several orders of magnitude lower than AQNs. Prezeau suggested that streaming DM constituents incident on the Earth should result in jet-like structures ("hairs") exiting the Earth, or a kind of caustics. Such ideas open novel directions in the search for DM. This work suggests a new analysis of the UFO results at the Large Hadron Collider (LHC), assuming that they are eventually, at least partly, due to AQNs. Firstly, a reanalysis of the existing data from the 4000 beam monitors since the beginning of the LHC is proposed, arguing that dust and AQNs should behave differently. The feasibility of this idea has been discussed with CERN accelerator people and potential collaborators.

    ↳ hep-exastro-ph.IMhep-ph5 citations
26. 26*

    Bulk Viscosity, Speed of Sound and Contact Structure at Intermediate Coupling

    Shivam Singh Kushwah🇮🇳 · Aalok Misra🇮🇳

    In the context of strongly coupled thermal QCD-like theories, the bulk viscosity($\zeta$)-to-shear viscosity($\eta$) ratio using the type IIA-theory dual of thermal QCD-like theories was shown to vary like $\frac{1}{3}-c_s^2$ (arXiv:1807.04713) ($c_s$ being the speed of sound), and the same ($\frac{\zeta }{\eta }$) at weak coupling using kinetic theory and finite temperature field theory, was shown and is known to vary like ${\left(\frac{1}{3}-c_s^2\right)}^2$ (arXiv:1807.04713). The novelties of the results of this paper are that we not only show for the first time from $\mathcal{M}$ theory that at intermediate coupling, with the inclusion of the $\mathcal{O}(R^4)$ corrections, the result obtained for $\frac{\zeta }{\eta }$ interpolates between the strong and weak coupling results in a way consistent with lattice computations of $SU(3)$ Gluodynamics (arXiv:0710.3717 [hep-lat]) within statistical errors (and within the temperature range permissible by our $\mathcal{M}$-theory uplift), but also observe that this behavior is related to the existence of Contact 3-Structures that exist only at intermediate coupling effected by the intermediate-$N$ "MQGP" limit of (arXiv:2211.13186[hep-th]). We also obtain an explicit dependence of $\frac{\zeta }{\eta }$ on (fractional powers of) the temperature-dependent/running gauge coupling (and its temperature derivative), and verify that the weak-coupling result dominates at large temperatures. We further conjecture that the aforementioned fractional-power-dependence of $\frac{\zeta }{\eta }$ on the gauge coupling is related to the lack of ``$N$-connectedness'' in the parameter space of Contact 3-Structures (as shown in arXiv:2211.13186[hep-th]).

    ↳ hep-thhep-phPRD(2024)·8 citations

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