Thu·Oct 13, 2022Thursday·October 13, 2022

1. 01*

   Indirect upper limits on ${\ell }_i\to {\ell }_j\gamma \gamma$ from ${\ell }_i\to {\ell }_j\gamma$

   Fabiola Fortuna🇲🇽 · Alejandro Ibarra🇩🇪 · Xabier Marcano🇪🇸 · Marcela Marín🇲🇽 · Pablo Roig🇲🇽

   We perform an effective field theory analysis to correlate the charged lepton flavor violating processes ${\ell }_i\to {\ell }_j\gamma \gamma$ and ${\ell }_i\to {\ell }_j\gamma$. Using the current upper bounds on the rate for ${\ell }_i\to {\ell }_j\gamma$, we derive model-independent upper limits on the rates for ${\ell }_i\to {\ell }_j\gamma \gamma$. Our indirect limits are about three orders of magnitude stronger than the direct bounds from current searches for $\mu \to e\gamma \gamma$, and four orders of magnitude better than current bounds for $\tau \to \ell \gamma \gamma$. We also stress the relevance of Belle II or a Super Tau Charm Facility to discover the rare decay $\tau \to \ell \gamma \gamma$.

   hep-phhep-exPRD(2023)·17 citations
2. 02*

   Enhanced neutrino polarizability

   Saurabh Bansal🇺🇸 · Gil Paz🇺🇸 · Alexey Petrov🇺🇸 · Michele Tammaro🇸🇮 · Jure Zupan🇺🇸

   We point out that neutrinos can have enhanced couplings to photons, if light (pseudo)scalar mediators are present, resulting in potentially measurable neutrino polarizability. We show that the expected suppression from small neutrino masses can be compensated by the light mediator mass, generating dimension 7 Rayleigh operators at low scales. We explore the rich phenomenology of such models, computing in details the constraints on the viable parameter space, spanned by the couplings of the mediator to neutrinos and photons. Finally, we build several explicit models that lead to enhanced neutrino polarizability by modifying the inverse see-saw majoron, i.e., the pseudo-Nambu-Goldstone boson of the $U(1{)}_L$ global lepton number responsible for generating small neutrino masses.

   hep-phhep-exJHEP(2023)·16 citations
3. 03*

   Gravity as a Portal to Reheating, Leptogenesis and Dark Matter

   Basabendu Barman🇨🇴 · Simon Cléry🇫🇷 · Raymond T. Co🇺🇸 · Yann Mambrini🇫🇷 · Keith A. Olive🇺🇸

   We show that a minimal scenario, utilizing only the graviton as an intermediate messenger between the inflaton, the dark sector and the Standard Model (SM), is able to generate $simultaneously$ the observed relic density of dark matter (DM), the baryon asymmetry through leptogenesis, as well as a sufficiently hot thermal bath after inflation. We assume an inflaton potential of the form $V(\varphi )\propto {\varphi }^k$ about the minimum at the end of inflation. The possibility of reheating via minimal gravitational interactions has been excluded by constraints on dark radiation for excessive gravitational waves produced from inflation. We thus extend the minimal model in several ways: i) we consider non-minimal gravitational couplings--this points to the parameter range of DM masses $M_{N_1}\simeq 2-10$ PeV, and right-handed neutrino masses $M_{N_2}\simeq (5-20)\times 10^{11}$ GeV, and $T_{\text{rh}}\lesssim 3\times 10^5$ GeV (for $k\le 20$); ii) we propose an explanation for the PeV excess observed by IceCube when the DM has a direct but small Yukawa coupling to the SM; and iii) we also propose a novel scenario, where the gravitational production of DM is a two-step process, first through the production of two scalars, which then decay to fermionic DM final states. In this case, the absence of a helicity suppression enhances the production of DM and baryon asymmetry, and allows a great range for the parameters including a dark matter mass below an MeV where dark matter warmness can be observable by cosmic 21-cm lines, even when gravitational interactions are responsible for reheating. We also show that detectable primordial gravitational wave signals provide the opportunity to probe this scenario for $T_{\text{rh}}\lesssim 5\times 10^6$ GeV in future experiments, such as BBO, DECIGO, CE and ET.

   hep-phJHEP(2022)·73 citations
4. 04*

   Systematic analysis of identified-hadron ${\mathbf{p}}_{\mathbf{t}}$ spectra from 13 TeV p-p collisions

   Thomas A. Trainor🇺🇸

   Identified-hadron (PID) $p_t$ spectra from 13 TeV $p$-$p$ collisions are compared with a two-component (soft+hard) model (TCM) that accurately distinguishes jet-related hadron production (hard component) from nonjet projectile-nucleon dissociation (soft component). The present $p$-$p$ study is similar to and is guided by recent TCM studies of PID spectra from 5 TeV $p$-Pb collisions. The combined analyses serve to establish a well-understood quantitative description of PID hadron production in small collision systems as a control experiment. The control can then be contrasted with conventional interpretations of collision data from more-central A-A collisions as indicating formation of a quark-gluon plasma (QGP). PID $p_t$ spectra from 13 TeV $p$-$p$ collisions exhibit simple consistency with spectra from 5 TeV $p$-Pb collisions. Hadron species abundances are consistent with statistical-model trends predicted prior to commencement of the large hadron collider program. Differential spectrum structure and various ratio measures are quantitatively explained by the TCM, including its jet contribution, and admit no room for claims of hydrodynamic flows in small collision systems.

   hep-ph7 citations
5. 05*

   Adding quark spin effects to PYTHIA string fragmentation

   Albi Kerbizi🇮🇹 · Leif Lönnblad🇸🇪

   Quark spin effects in hadronization have been recently included in the PYTHIA 8 event generator for the simulation of the deep inelastic scattering (DIS) process off a polarized nucleon target via the external StringSpinner package. The spin effects can be simulated for the production of pseudoscalar mesons using the string+${}^3{P}_0$ model of polarized quark fragmentation and parametrizations of the transversity PDFs. We present here a major development of StringSpinner which includes the production of vector mesons in the polarized PYTHIA 8 string fragmentation as well as their polarized decays. The package is validated and used to simulate the transverse-spin asymmetries in semi-inclusive DIS (SIDIS). The simulation results on the Collins and dihadron asymmetries for the final state mesons are compared with the asymmetries measured in SIDIS off transversely polarized protons. Also shown are the predictions for the Collins asymmetries for $\rho$ mesons produced in SIDIS off transversely polarized protons.

   hep-phPoS(2022)·1 citation
6. 06*

   The invariance of inelastic overlap function

   S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺

   We consider the symmetry property of the inelastic overlap function and its relation to the reflective scattering mode appearance.

   hep-phParticles(2023)·2 citations
7. 07*

   NNLO B-fragmentation fits and their application to $t\bar{t}$ production and decay at the LHC

   Michał Czakon🇩🇪 · Terry Generet🇩🇪 · Alexander Mitov🇬🇧 · Rene Poncelet🇬🇧

   In this work we derive three sets of non-perturbative fragmentation functions, with uncertainties, for $B$-hadrons, $J/\psi$'s and muons resulting from semileptonic $B$ decays. All three sets are with next-to-next-to leading order accuracy and include next-to-next-to leading logarithmic soft gluon resummation. The novel feature of these new sets is that they are fully consistent with our formalism for next-to-next-to leading order (NNLO) calculations for final states with identified $B$, $J/\psi$ or a $\mu$. We employ the fragmentation functions derived in this work to make state of the art predictions for such final states in $t\bar{t}$ events at the LHC. A special emphasis is placed on observables sensitive to the top quark mass. The present work opens the door for many LHC applications, like, open $B$ production or $B$ production in association with bosons.

   hep-phhep-exJHEP(2023)·38 citations
8. 08*

   Possible molecular states of ${\bar{D}}^{\ast }{K}^{\ast }$ ($D^{\ast }{K}^{\ast }$) and the new exotic states $X_0(2900)$ and $X_1(2900)$ ($T_{cs0}^a(2900{)}^0$ and $T_{cs0}^a(2900{)}^{++}$)

   Hong-Wei Ke🇨🇳 · Yi-Fan Shi🇨🇳 · Xiao-Hai Liu🇨🇳 · Xue-Qian Li🇨🇳

   Two iso-singlet hadron states $X_0(2900)$ and $X_1(2900)$ with $J=0$ and 1 respectively, discovered by the LHCb collaboration in 2020, were identified as molecular bound states of ${\bar{D}}^{\ast }{K}^{\ast }$. Recently two structures $T_{cs0}^a(2900{)}^0$ and $T_{cs0}^a(2900{)}^{++}$ have been observed at the hadron spectra, one would suspect if they also are molecular states of $D^{\ast }$ and $K^{\ast }$. As long as they were of the molecular structures of $D^{\ast }{K}^{\ast }$, the hadron states must be in an iso-vector, namely $T_{cs0}^a(2900{)}^0$ and $T_{cs0}^a(2900{)}^{++}$ were $I_3=-1,1$ components of the iso-vector. If it is the case, the corresponding $T_{cs0}^a(2900{)}^{+}$ of ($I=1,I_3=0$) and $T_{cs0}^{{}^{\prime }a}(2900{)}^{+}$ of $I=0,I_3=0$ so far evade experimental observation, but should be found by the future experiments. To testify this ansatz, in this paper we study the possible molecular structures of ${\bar{D}}^{\ast }{K}^{\ast }$ and $D^{\ast }{K}^{\ast }$ within the Bethe-Salpeter (B-S) framework. With reasonable input parameters it is found that ${\bar{D}}^{\ast }{K}^{\ast }$ iso-scalar systems with $J^P=0^{+}$ and $1^{+}$ are solutions. The result supports the ansatz of $X_0(2900)$ ($X_1(2900)$) being molecular states of ${\bar{D}}^{\ast }{K}^{\ast }$. Whereas for the system of $D^{\ast }{K}^{\ast }$ with $I=1$ the corresponding B-S equation has no solution. Thus we can draw a clear conclusion that $T_{cs0}^a(2900{)}^0$ and $T_{cs0}^a(2900{)}^{++}$ should not be bound states of $D^{\ast }$ and $K^{\ast }$. The two structures observed by the LHCb collaboration may be caused by dynamics, such as the well-recognized triangle anomalies or other mechanisms.

   hep-phhep-exPRD(2022)·32 citations
9. 09*

   Formation of hot spots around small primordial black holes

   Minxi He🇯🇵 · Kazunori Kohri🇯🇵 · Kyohei Mukaida🇯🇵 · Masaki Yamada🇯🇵

   In this paper, we investigate the thermalization of Hawking radiation from primordial black holes (PBHs) in the early Universe, taking into account the interference effect on thermalization of high energy particles, known as Landau-Pomeranchuk-Migdal (LPM) effect. Small PBHs with masses $\lesssim 10^9\mathrm{g}$ completely evaporate before the big bang nucleosynthesis (BBN). The Hawking radiation emitted from these PBHs heats up the ambient plasma with temperature lower than the Hawking temperature, which results in a non-trivial temperature profile around the PBHs, namely a hot spot surrounding a PBH with a broken power-law tail. We find that the hot spot has a core with a radius much larger than the black hole horizon and its highest temperature is independent of the initial mass of the PBH such as $2\times 10^9\mathrm{GeV}\times (\alpha /0.1{)}^{19/3}$, where $\alpha$ generically represents the fine-structure constants. We also briefly discuss the implications of the existence of the hot spot for phenomenology.

   hep-phastro-ph.COJCAP(2023)·33 citations
10. 10*

    Wash-in leptogenesis after axion inflation

    Valerie Domcke🇨🇭 · Kohei Kamada🇯🇵 · Kyohei Mukaida🇯🇵 · Kai Schmitz🇩🇪 · Masaki Yamada🇯🇵

    CP violation and the violation of baryon-minus-lepton number B-L do not necessarily have to occur simultaneously in order to accomplish successful leptogenesis. Instead, it suffices if new CP-violating interactions at high energies result in primordial charge asymmetries, which are then reprocessed into a nonvanishing B-L asymmetry by right-handed neutrinos (RHNs) at lower energies. In this paper, we study this novel mechanism known as "wash-in leptogenesis", utilizing axion inflation as the source of high-scale CP violation. We specifically consider axion inflation coupled to the Standard Model hypercharge sector, which results in the dual production of hypermagnetic helicity and fermionic charge asymmetries. Although the survival of these charges is endangered by sphaleron processes, magnetic diffusion, and the chiral plasma instability, we find a large range of viable scenarios. We consistently account for RHN flavor effects and coherence among the Standard Model lepton flavors across a wide range of RHN masses. We find a lower bound of 10^(5...9) GeV on the mass of the lightest RHN involved in wash-in leptogenesis, depending on the onset of turbulence in the chiral plasma and the Hubble scale of inflation. Our model is representative of a broader class of new leptogenesis scenarios and suggests interesting observational signatures with regard to intergalactic magnetic fields, primordial black holes, and gravitational waves.

    hep-phastro-ph.COJHEP(2023)·39 citations
11. 11*

    Recoil corrections to the energy levels of hydrogenic atoms

    Gregory S. Adkins🇺🇸 · Jonathan Gomprecht🇺🇸 · Yanxi Li🇨🇳 · Evan Shinn🇺🇸

    We have completed the calculation of pure-recoil corrections of order $(Z\alpha {)}^6$ to Coulombic bound states of two spin-1/2 fermions without approximation in the particle masses. Our result applies to systems of arbitrary mass ratio such as muonium and positronium, and also hydrogen and muonic hydrogen (with the neglect of proton structure effects). We have shown how the two-loop master integrals that occur in the relativistic region can be computed in analytic form, and suggest that the same method can be applied to the three-loop integrals that would be present in a calculation of order $(Z\alpha {)}^7$ corrections.

    hep-phphysics.atom-phPRL(2023)·12 citations
12. 12*

    Machine learning-based jet and event classification at the Electron-Ion Collider with applications to hadron structure and spin physics

    Kyle Lee🇺🇸 · James Mulligan🇺🇸 · Mateusz Płoskoń🇺🇸 · Felix Ringer🇺🇸 · Feng Yuan🇺🇸

    We explore machine learning-based jet and event identification at the future Electron-Ion Collider (EIC). We study the effectiveness of machine learning-based classifiers at relatively low EIC energies, focusing on (i) identifying the flavor of the jet and (ii) identifying the underlying hard process of the event. We propose applications of our machine learning-based jet identification in the key research areas at the future EIC and current Relativistic Heavy Ion Collider program, including enhancing constraints on (transverse momentum dependent) parton distribution functions, improving experimental access to transverse spin asymmetries, studying photon structure, and quantifying the modification of hadrons and jets in the cold nuclear matter environment in electron-nucleus collisions. We establish first benchmarks and contrast the estimated performance of flavor tagging at the EIC with that at the Large Hadron Collider. We perform studies relevant to aspects of detector design including particle identification, charge information, and minimum transverse momentum capabilities. Additionally, we study the impact of using full event information instead of using only information associated with the identified jet. These methods can be deployed either on suitably accurate Monte Carlo event generators, or, for several applications, directly on experimental data. We provide an outlook for ultimately connecting these machine learning-based methods with first principles calculations in quantum chromodynamics.

    hep-phnucl-exnucl-thJHEP(2023)·28 citations
13. 13*

    On the Sensitivity of Spin-Precession Axion Experiments

    Jeff A. Dror🇺🇸 · Stefania Gori🇺🇸 · Jacob M. Leedom🇩🇪 · Nicholas L. Rodd🇨🇭

    A leading direction in the hunt for axion dark matter is to search for its influence on nuclear spins. The detection scheme involves polarizing a sample of nuclei within a strong static magnetic field and then looking for a spin precession induced by the oscillating axion field. We study the axion signal and background contributions that arise in such experiments (a prominent example being CASPEr), finding key differences with the existing literature. Most importantly, in the limit where the transverse spin-relaxation time of the material is the largest timescale of the problem, we show that the induced signal continues to grow even beyond the coherence time of the axion field. As a result, we find that spin-precession instruments are much more sensitive than what has been previously estimated in a sizable range of axion masses, with sensitivity improvement of up to a factor of 100 at an axion mass of 100 neV using a Xenon-129 sample. This improves the detection prospects for the QCD axion, and we estimate the experimental requirements to reach this motivated target. Our results apply to both the axion electric and magnetic dipole moment operators.

    hep-phastro-ph.COhep-exPRL(2023)·41 citations
14. 14*

    Freezing In Vector Dark Matter Through Magnetic Dipole Interactions

    Gordan Krnjaic🇺🇸 · Duncan Rocha🇺🇸 · Anastasia Sokolenko🇺🇸

    We study a simple model of vector dark matter that couples to Standard Model particles via magnetic dipole interactions. In this scenario, the cosmological abundance arises through the freeze-in mechanism and depends on the dipole coupling, the vector mass, and the reheat temperature. To ensure cosmological metastability, the vector must be lighter than the fermions to which it couples, but rare decays can still produce observable 3$\gamma$ final states; two-body decays can also occur at one-loop with additional weak suppression, but are subdominant if the vector couples mainly to light fermions. For sufficiently heavy vectors, induced kinetic mixing with the photon can also yield additional two body decays to lighter fermions and predict indirect detection signals through final state radiation. We explore the implications of couplings to various flavors of visible particles and emphasize leptophilic dipoles involving electrons, muons, and taus, which offer the most promising indirect detection signatures through 3$\gamma$, $e^{+}{e}^{-}\gamma$, and ${\mu }^{+}{\mu }^{-}\gamma$ decay channels. We also present constraints from current and past telescopes, and sensitivity projections for future missions including e-ASTROGAM and AMEGO.

    hep-phastro-ph.COPRD(2023)·10 citations
15. 15*

    The Migdal Effect in Semiconductors for Dark Matter with Masses below $\sim$100 MeV

    Kim V. Berghaus🇺🇸 · Angelo Esposito🇮🇹 · Rouven Essig🇺🇸 · Mukul Sholapurkar🇺🇸

    Dark matter scattering off a nucleus has a small probability of inducing an observable ionization through the inelastic excitation of an electron, called the Migdal effect. We use an effective field theory to extend the computation of the Migdal effect in semiconductors to regions of small momentum transfer to the nucleus, where the final state of the nucleus is no longer well described by a plane wave. Our analytical result can be fully quantified by the measurable dynamic structure factor of the semiconductor, which accounts for the vibrational degrees of freedom (phonons) in a crystal. We show that, due to the sum rules obeyed by the structure factor, the inclusive Migdal rate and the shape of the electron recoil spectrum is well captured by approximating the nuclei in the crystal as free ions; however, the exclusive differential rate with respect to energy depositions to the crystal depends on the phonon dynamics encoded in the dynamic structure function of the specific material. Our results now allow the Migdal effect in semiconductors to be evaluated even for the lightest dark matter candidates ($m_{\chi }\gtrsim 1$ MeV) that can kinematically excite electrons.

    hep-phastro-ph.COJHEP(2023)·47 citations
16. 16*

    Nucleon transverse quark spin densities

    Constantia Alexandrou🇨🇾 · Simone Bacchio🇨🇾 · Martha Constantinou🇺🇸 · Petros Dimopoulos🇮🇹 · Jacob Finkenrath🇨🇾 · Roberto Frezzotti🇮🇹 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Bartosz Kostrzewa🇩🇪 · Giannis Koutsou🇨🇾 · Gregoris Spanoudes🇨🇾 · Carsten Urbach🇩🇪

    We present a calculation of the Mellin moments of the nucleon transverse quark spin densities extracted from the unpolarized and transversity generalized form factors. We use three $N_F=2+1+1$ ensembles of twisted mass fermions with quark masses tuned to their physical values and lattice spacings $a\sim 0.08$~fm, $a\sim 0.07$~fm and $a\sim 0.06$~fm and extrapolate the form factors to the continuum limit. Besides isovector densities we also include results for the tensor charge for each quark flavor using the ensemble with $a\sim 0.08$~fm for which we include the disconnected contributions.

    ↳ hep-lathep-phnucl-thPoS(2023)·2 citations
17. 17*

    Constraining Neutrinoless Double-Beta Decay Matrix Elements from Ab Initio Nuclear Theory

    A. Belley🇨🇦 · T. Miyagi🇩🇪 · S. R. Stroberg🇺🇸 · J. D. Holt🇨🇦

    As experimental searches for neutrinoless double-beta ($0\nu \beta \beta$) decay are entering a new generation, with hopes to completely probe the inverted mass hierarchy, the need for reliable nuclear matrix elements, which govern the rate of this decay, is stronger than ever. Since a large discrepancy in results is typically found with nuclear modela, a large unknown still exists on the sensitivity of these experiments to the effective neutrino mass. We consider this problem from a first-principles perspective, using the ab initio valence-space in medium similarity renormalization group. In particular, we study correlations of the $0\nu \beta \beta$-decay matrix elements in ${}^{76}$Ge with other observables, such as the double Gamow-Teller giant resonance, from 34 input chiral interactions in an attempt to constrain our uncertainties and investigate the interaction dependence of the nuclear matrix element.

    ↳ nucl-thhep-phnucl-exAIP Conf.Proc.(2025)·10 citations
18. 18*

    EFT for de Sitter Space

    Daniel Green🇺🇸

    The physics of de Sitter space is essential to our understanding of our cosmological past, present, and future. It forms the foundation for the statistical predictions of inflation in terms of quantum vacuum fluctuations that are being tested with cosmic surveys. In addition, the current expansion of the universe is dominated by an apparently constant vacuum energy and we again find our universe described by a de Sitter epoch. Despite the success of our predictions for cosmological observables, conceptual questions of the nature of de Sitter abound and are exacerbated by technical challenges in quantum field theory and perturbative quantum gravity in curved backgrounds. In recent years, significant process has been made using effective field theory techniques to tame these breakdowns of perturbation theory. We will discuss how to understand the long-wavelength fluctuations produced by accelerating cosmological backgrounds and how to resolve both the UV and IR obstacles that arise. Divergences at long wavelengths are resummed by renormalization group (RG) flow in the EFT. For light scalar fields, the RG flow manifests itself as the stochastic inflation formalism. In single-field inflation, long-wavelength metric fluctuations are conserved outside the horizon to all-loop order, which can be understood easily in EFT terms from power counting and symmetries.

    ↳ hep-thastro-ph.COhep-ph28 citations
19. 19*

    The Future of High Energy Physics Software and Computing

    V. Daniel Elvira · Steven Gottlieb🇺🇸 · Oliver Gutsche · Benjamin Nachman (frontier conveners) · S. Bailey🇺🇸 · W. Bhimji🇺🇸 · P. Boyle · G. Cerati🇺🇸 · M. Carrasco Kind🇺🇸 · K. Cranmer🇺🇸 · G. Davies🇬🇧 · V. D. Elvira and 16 other authors

    Software and Computing (S&C) are essential to all High Energy Physics (HEP) experiments and many theoretical studies. The size and complexity of S&C are now commensurate with that of experimental instruments, playing a critical role in experimental design, data acquisition/instrumental control, reconstruction, and analysis. Furthermore, S&C often plays a leading role in driving the precision of theoretical calculations and simulations. Within this central role in HEP, S&C has been immensely successful over the last decade. This report looks forward to the next decade and beyond, in the context of the 2021 Particle Physics Community Planning Exercise ("Snowmass") organized by the Division of Particles and Fields (DPF) of the American Physical Society.

    ↳ hep-exhep-lathep-phhep-th11 citations
20. 20*

    Testing the mean field theory of scalar field dark matter

    Andrew Eberhardt🇺🇸 · Alvaro Zamora🇺🇸 · Michael Kopp🇸🇪 · Tom Abel🇺🇸

    Scalar field dark matter offers an interesting alternative to the traditional WIMP dark matter picture. Astrophysical and cosmological simulations are useful to constraining the mass of the dark matter particle in this model. This is particularly true at low mass where the wavelike nature of the dark matter particle manifests on astrophysical scales. These simulations typical use a classical field approximation. In this work, we look at extending these simulations to include quantum corrections. We look into both the ways in which large corrections impact the predictions of scalar field dark matter, and the timescales on which these corrections grow large. Corrections tend to lessen density fluctuations and increase the effect of "quantum pressure". During collapse, these corrections grow exponentially, quantum corrections would become important in about ~30 dynamical times. This implies that the predictions of classical field simulations may differ from those with quantum corrections for systems with short dynamical times.

    ↳ astro-ph.COhep-phSciPost Phys.Proc.(2023)·3 citations
21. 21*

    Vacuum Decay and Euclidean Lattice Monte Carlo

    Jiayu Shen🇺🇸 · Patrick Draper🇺🇸 · Aida X. El-Khadra🇺🇸

    The decay rate of a metastable vacuum is usually calculated using a semiclassical approximation to the Euclidean path integral. The extension to a complete Euclidean lattice Monte Carlo computation, however, is hampered by analytic continuations that are ill-suited to numerical treatment, and the nonequilibrium nature of a metastable state. In this paper we develop a new methodology to compute vacuum decay rates from Monte Carlo simulations of Euclidean lattice theories. To test the new method, we consider simple quantum mechanical systems systems with metastable vacua. This work can be extended to Euclidean field theories, which we discuss in the Conclusions.

    ↳ hep-lathep-phhep-thPRD(2023)·5 citations
22. 22*

    Decaying Dark Matter and Lyman-$\alpha$ forest constraints

    Lea Fuß🇩🇪 · Mathias Garny🇩🇪

    Decaying Cold Dark Matter (DCDM) is a model that is currently under investigation regarding primarily the $S_8$ tension between cosmic microwave background (CMB) and certain large-scale structure measurements. The decay into one massive and one (or more) massless daughter particle(s) leads to a suppression of the power spectrum in the late universe that depends on the relative mass splitting $ϵ=(1-m^2/M^2)/2$ between the mother and massive daughter particle as well as the lifetime $\tau$. In this work we investigate the impact of the BOSS DR14 one-dimensional Lyman-$\alpha$ forest flux power spectrum on the DCDM model using a conservative effective model approach to account for astrophysical uncertainties. Since the suppression of the power spectrum due to decay builds up at low redshift, we find that regions in parameter space that address the $S_8$ tension can be well compatible with the Lyman-$\alpha$ forest. Nevertheless, for values of the degeneracy parameter $ϵ\sim 0.1-0.5\%$, for which the power suppression occurs within the scales probed by BOSS Lyman-$\alpha$ data, we find improved constraints compared to previous CMB and galaxy clustering analyses, obtaining $\tau \gtrsim 18$ Gyrs for small mass splitting. Furthermore, our analysis of the BOSS Lyman-$\alpha$ flux power spectrum allows for values $\tau \sim 10^2$ Gyrs, $ϵ\sim 1\%$, that have been found to be preferred by a combination of Planck and galaxy clustering data with a KiDS prior on $S_8$, and we even find a marginal preference within this regime.

    ↳ astro-ph.COhep-phJCAP(2023)·37 citations
23. 23*

    Multi-messenger constraints on Abelian-Higgs cosmic string networks

    Mark Hindmarsh🇫🇮 · Jun'ya Kume🇯🇵

    Nielsen-Olesen vortices in the Abelian-Higgs (AH) model are the simplest realisations of cosmic strings in a gauge field theory. Large-scale numerical solutions show that the dominant decay channel of a network of AH strings produced from random initial conditions is classical field radiation. However, they also show that with special initial conditions, loops of string can be created for which classical field radiation is suppressed, and which behave like Nambu-Goto (NG) strings with a dominant decay channel into gravitational radiation. This indicates that cosmic strings are generically sources of both high-energy particles and gravitational waves. Here we adopt a simple parametrisation of the AH string network allowing for both particle and gravitational wave production. With a reference to a specific model for NG-like loop distribution, this sets the basis for a ``multi-messenger'' investigation of this model. We find that, in order to explain the NANOGrav detection of a possible gravitational wave background, while satisfying the constraint on NG-like loop production from simulations and bounds from the cosmic microwave background, the tension of the AH string in Planck units $G\mu$ and the fraction of the NG-like loops $f_{\mathrm{NG}}$ should satisfy $G\mu f_{\mathrm{NG}}^{2.6}\gtrsim 3.2\times 10^{-13}$ at 95$\%$ confidence. On the other hand, for such string tensions, constraints from the diffuse gamma-ray background (DGRB) indicate that more than 97$\%$ of the total network energy should be converted to dark matter (DM) or dark radiation. We also consider joint constraints on the annihilation cross-section, the mass, and the relic abundance of DM produced by decays of strings. For example, for a DM mass of 500 GeV, the observed relic abundance can be explained by decaying AH strings that also account for the NANOGrav signal.

    ↳ astro-ph.COgr-qchep-phJCAP(2023)·45 citations
24. 24*

    Use of Superfluid Helium to Observe Directionality of Galactic Dark Matter

    George M. Seidel🇺🇸 · Christian Enss🇩🇪

    The quasiparticle propagation away from the track of a highly ionizing particle in superfluid helium at low temperatures has previously been shown to exhibit anisotropy. We discuss the mechanism responsible for this behavior and show that it occurs for nuclear scattering by dark matter for recoil energies down to a few keV, and perhaps lower. This makes it possible to extend WIMP searches with interaction cross sections that reach into the neutrino floor in a meaningful energy range.

    ↳ astro-ph.IMhep-phJ.Low Temp.Phys.(2024)·2 citations
25. 25*

    Lorentz invariance violation induced threshold anomaly versus very-high energy cosmic photon emission from GRB 221009A

    Hao Li🇨🇳 · Bo-Qiang Ma🇨🇳

    It has been reported that the Large High Altitude Air Shower Observatory (LHAASO) observed very high energy photons from GRB 221009A, with the highest energy reaching 18~TeV. We find that observation of such high energy photons is quite nontrivial since extragalactic background light could absorb these photons severely and the flux is too weak to be observed. Therefore we discuss a potential mechanism for us to observe these photons, and suggest that Lorentz invariance violation induced threshold anomaly of the process \(\gamma\gamma\to e^-e^+\) provides a candidate to explain this phenomenon.

    ↳ astro-ph.HEgr-qchep-phAstropart.Phys.(2023)·56 citations
26. 26*

    The local dark matter distribution in self-interacting dark matter halos

    Elham Rahimi🇨🇦 · Evan Vienneau🇨🇦 · Nassim Bozorgnia🇨🇦 · Andrew Robertson🇺🇸

    We study the effects of dark matter self-interactions on the local dark matter distribution in selected Milky Way-like galaxies in the EAGLE hydrodynamical simulations. The simulations were run with two different self-interacting dark matter models, a constant and velocity-dependent self-interaction cross-section. We find that the local dark matter velocity distribution of the Milky Way-like halos in the simulations with dark matter self-interactions and baryons are generally similar to those extracted from cold collisionless dark matter simulations with baryons. In both cases, the local dark matter speed distributions agree well with their best fit Maxwellian distributions. Including baryons in the simulations with or without dark matter self-interactions increases the local dark matter density and shifts the dark matter speed distributions to higher speeds. To study the implications for direct detection, we compute the dark matter halo integrals obtained directly from the simulations and compare them to those obtained from the best fit Maxwellian velocity distribution. We find that a Maxwellian distribution provides a good fit to the halo integrals of most halos, without any significant difference between the results of different dark matter self-interaction models.

    ↳ astro-ph.COastro-ph.GAhep-phJCAP(2023)·9 citations
27. 27*

    Determining the spin of light primordial black holes with Hawking radiation

    Marco Calzà🇵🇹 · João G. Rosa🇵🇹

    We propose a method to determine the mass and spin of primordial black holes (PBHs) in the mass range $5\times 10^7-10^{12}$ kg (Hawking temperatures $\sim 10$ MeV $-200$ GeV), based on measuring the energy of specific features in the photon Hawking emission spectrum, including both primary and secondary components. This is motivated by scenarios where PBHs in this mass range spin up as they evaporate, namely the string axiverse, where dimensionless spin parameters $\tilde{a}\sim 0.1-0.5$ can be achieved through the Hawking emission of hundreds or even thousands of light axion-like particles. Measuring the present PBH mass-spin distribution may thus be an important probe of physics beyond the Standard Model. Since the proposed method relies on the energy of the photons emitted by a given PBH, rather than on the associated flux, it is independent of the PBH-Earth distance and, as a byproduct, can also be used to infer the latter.

    ↳ gr-qcastro-ph.HEhep-phJHEP(2022)·18 citations

* 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.