Mon·Sep 18, 2023Monday·September 18, 2023

1. 01*

   Testing Bell inequality through $h\to \tau \tau$ at CEPC

   Kai Ma🇨🇳 · Tong Li🇨🇳

   The decay of Higgs boson into two spin-1/2 particles provides an ideal system to reveal quantum entanglement and Bell-nonlocality. Future $e^{+}{e}^{-}$ colliders can improve the measurement accuracy of the spin correlation of tau lepton pairs from Higgs boson decay. We show the testability of Bell inequality through $h\to \tau \tau$ at Circular Electron Positron Collider (CEPC). Two realistic methods of testing Bell inequality are investigated, i.e., Törnqvist's method and Clauser-Home-Shimony-Holt (CHSH) inequality. In the simulation, we take into account the detector effects of CEPC including uncertainties for tracks and jets from $Z$ boson in the production of $e^{+}{e}^{-}\to Zh$. Necessary reconstruction approaches are described to measure quantum entanglement between ${\tau }^{+}$ and ${\tau }^{-}$. Finally, we show the sensitivity of CEPC to the Bell inequality violation for the two methods.

   hep-phhep-exCPC(2024)·54 citations
2. 02*

   Angular distribution of the FCNC process $B_c\to D_s^{\ast }(\to D_s\pi ){\ell }^{+}{\ell }^{-}$

   Yu-Shuai Li🇨🇳 · Xiang Liu🇨🇳

   In this work, we study the flavor-changing neutral-current process $B_c\to D_s^{\ast }(\to D_s\pi ){\ell }^{+}{\ell }^{-}$ ($\ell$= $e$, $\mu$, $\tau$). The relevant weak transition form factors are obtained by using the covariant light-front quark model, in which, the main inputs, i.e., the meson wave functions of $B_c$ and $D_s^{\ast }$, are adopted as the numerical wave functions from the solution of the Schrödinger equation with the modified Godfrey-Isgur model. With the obtained form factors, we further investigate the relevant branching fractions and their ratios, and some angular observables, i.e., the forward-backward asymmetry $A_{FB}$, the polarization fractions $F_{L(T)}$, and the $CP$-averaged angular coefficients $S_i$ and the $CP$ asymmetry coefficients $A_i$. We also present our results of the clean angular observables $P_{1,2,3}$ and $P_{4,5,6,8}^{\prime }$, which can reduce the uncertainties from the form factors. Our results show that the corresponding branching fractions of the electron or muon channels can reach up to $10^{-8}$. With more data being accumulated in the LHCb experiment, our results are helpful for exploring this process, and deepen our understanding of the physics around the $b\to s{\ell }^{+}{\ell }^{-}$ process.

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

   Perturbative Asymptotic Safety and Its Phenomenological Applications

   Alexander Bednyakov🇷🇺 · Alfiia Mukhaeva🇷🇺

   Asymptotic safety is a remarkable example when fruitful ideas borrowed from statistical physics proliferate to high-energy physics. The concept of asymptotic safety is tightly connected to fixed points (FPs) of the renormalization-group (RG) flow, and generalize well-known asymptotic freedom to a scale-invariant ultraviolet completion with non-vanishing interactions. In this review, we discuss the key ideas behind asymptotic safety, a mechanism for achieving it, and the conditions it imposes on general gauge-Yukawa field theories. We also pay special attention to possible phenomenological applications and provide an overview of standard model (SM) extensions potentially exhibiting asymptotic safety.

   hep-phhep-thSymmetry(2023)·9 citations
4. 04*

   Using photon-hadron production to impose restrictions on heavy-hadrons fragmentation functions

   German F. R. Sborlini🇪🇸 · Roger Hernández-Pinto🇲🇽 · Salvador Ochoa-Oregon🇲🇽 · David F. Rentería-Estrada🇪🇸

   Fragmentation Functions (FF) are universal non-perturbative objects that model hadronization in some general kind of processes. They are mainly extracted from experimental data, hence constraining the parameters of the corresponding fits is crucial for achieving reliable results. As expected, the production of lighter hadrons is favoured w.r.t. heavy ones, thus we would like to exploit the precise knowledge of pion FFs to constraint the shape of kaon (or heavier) FFs. In this talk, we show how imposing specific cuts on photon-hadron production leads to relations between the $u$-started FFs. For doing so, we exploit the reconstruction of momentum fractions in terms of experimentally-accessible quantities and introduce NLO QCD + LO QED corrections to reduce the theoretical uncertainties.

   hep-phhep-exPoS(2024)·0 citations
5. 05*

   Common origin of dark matter, baryon asymmetry and neutrino masses in the standard model with extended scalars

   Sin Kyu Kang🇰🇷 · Raymundo Ramos🇰🇷

   We propose a model that simultaneously addresses the existence of a dark matter candidate, baryon asymmetry and tiny neutrino masses and mixing by introducing two SU(2) triplet scalars and an inert SU(2) doublet scalar on top of the standard model. The two triplet scalars serve as mediators in generation of lepton asymmetry and determination of relic density of dark matter. They also play an essential role in generation of tiny neutrino masses and inducing CP violation. The inert scalar is regarded as a dark matter candidate. The interference due to complex Breit-Wigner propagators for the triplets will result in CP-asymmetry that depends on the difference between their masses and a relative complex phase between their couplings to standard model leptons. Moreover, the production of lepton asymmetry will be closely tied to the evolution of dark matter, limiting the parameter space where the correct relic abundance and matter-antimatter asymmetry can be simultaneously accomplished.

   hep-phJ.Korean Phys.Soc.(2024)·1 citation
6. 06*

   Exploring jet transport coefficients by elastic and radiative scatterings in the strongly interacting quark-gluon plasma

   Ilia Grishmanovskii🇩🇪 · Taesoo Song🇩🇪 · Olga Soloveva🇩🇪 · Carsten Greiner🇩🇪 · Elena Bratkovskaya🇩🇪

   We investigate the interaction of leading jet partons within a strongly interacting quark-gluon plasma (sQGP) medium, using the effective dynamical quasiparticle model (DQPM). The DQPM offers a description of the sQGP's non-perturbative nature at finite temperature $T$ and baryon chemical potential ${\mu }_B$ through a propagator representation of massive off-shell partons (quarks and gluons). These partons are characterized by spectral functions with $T,{\mu }_B$ dependent masses and widths, adjusted to reproduce the lattice Quantum Chromodynamics (lQCD) equation-of-state (EoS) for the QGP in thermodynamic equilibrium. Our focus lies on examining the jet transport coefficients by elastic scattering in sQGP, specifically the transverse momentum transfer squared per unit length denoted as $\hat{q}$, within the QGP. Furthermore, we investigate the dependence of these coefficients on both the medium temperature $T$ and the jet parton energy. By studying the jet transport coefficients and their relationship to temperature and parton energy, we aim to gain insights into the dynamics of jet propagation in the strongly interacting quark-gluon plasma medium.

   hep-phnucl-thPoS(2024)·1 citation
7. 07*

   Scalar dark matter production from the inflaton

   Mathias Pierre🇩🇪

   A curved space-time is known to act as a source for particle production in environments where gravity plays a significant role. We explore this effect in a minimal setup of cosmic inflation on the production of a scalar dark matter candidate during and after the inflationary stage of the universe. We consider the production of dark matter via direct coupling to the inflaton field or from pure gravitational interactions. Cosmological constraints from structure formation and dark matter isocurvature perturbations are discussed. A new analytical expression for the isocurvature power spectrum is provided.

   hep-phastro-ph.COhep-th1 citation
8. 08*

   Investigating radial flow-like effects via pseudorapidity and transverse spherocity dependence of particle production in pp collisions at the LHC

   Aswathy Menon Kavumpadikkal Radhakrishnan🇮🇳 · Suraj Prasad🇮🇳 · Sushanta Tripathy🇨🇭 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳

   Recent observations of quark-gluon plasma (QGP) like signatures in high multiplicity proton-proton (pp) collisions, have compelled the heavy-ion physics community to re-examine small collision systems for proper baseline studies. Event-shape-based studies in pp collisions have succeeded to a certain extent in identifying the rare events mimicking such heavy-ion-like behaviour. In this study, we incorporate PYTHIA8 and AMPT to study radial flow-like signatures in pp collisions at $\sqrt{s}=13$ TeV as a function of transverse spherocity and pseudorapidity. The selection of softer events possibly carrying heavy-ion-like features is performed using the transverse spherocity event-shape observable. As the particle production mechanism in midrapidity differs greatly from the forward rapidity, a pseudorapidity-dependent study is meaningful. Keeping ALICE 3 upgrades at the LHC in mind, this study aims to demonstrate the transverse spherocity and pseudorapidity dependence of the mean transverse momentum, particle ratios, and kinetic freezeout parameters in pp collisions at $\sqrt{s}$ = 13 TeV using PYTHIA8. We observe that the isotropic events show enhanced radial-flow effects in all multiplicity classes, however, the jetty events show signatures of the radial flow-like effects only in high-multiplicity events. For the first time, we show the transverse spherocity and pseudorapidity dependence of partonic modification factor in pp collisions, which clearly shows that by choosing transverse spherocity, one can directly probe the radial flow-like effects in pp collisions at the LHC.

   hep-phhep-exnucl-exnucl-thEur.Phys.J.Plus(2025)·8 citations
9. 09*

   On Higgs+jet production at next-to-leading power accuracy

   Sourav Pal🇮🇳 · Satyajit Seth🇮🇳

   We present computation of the next-to-leading power corrections for Higgs plus one jet production in a hadron collider via gluon fusion channel. Shifting of spinors in the helicity amplitudes without additional radiation captures the leading next-to-soft radiative behaviour and makes the calculation tractable. We establish the connection between the shifted dipole spinors and the colour ordered radiative amplitudes. We find that next-to-maximal helicity violating amplitudes do not play a role in this correction. Compact analytic expressions of next-to-leading power leading logarithms coming from different helicity configurations are shown.

   hep-phPRD(2024)·23 citations
10. 10*

    Pole-fitting for complex functions: enhancing standard techniques by artificial-neural-network classifiers and regressors

    S. Kaidisch🇦🇹 · T. U. Hilger🇩🇪 · A. Krassnigg🇦🇹 · W. Lucha🇦🇹

    Motivated by a use case in theoretical hadron physics, we revisit an application of a pole-sum fit to dressing functions of a confined quark propagator. More precisely, we investigate approaches to determine the number and positions of the singularities closest to the origin for a function that is only known numerically on a specific finite grid of values on the positive real axis. For this problem, we compare the efficiency of standard techniques, like the Levenberg-Marquardt algorithm, to a pure artificial-neural-network approach as well as a combination of these two. This combination is more efficient than any of the two techniques separately. Such an approach is generalizable to similar situations, where the positions of poles of a function in a complex variable must be quickly and reliably estimated from real-axis information alone.

    hep-phComput.Phys.Commun.(2024)·0 citations
11. 11*

    Gravitational waves from axion wave production

    Mingqiu Li🇨🇳 · Sichun Sun🇨🇳 · Qi-Shu Yan🇨🇳 · Zhijie Zhao🇨🇳

    We consider a scenario with axions/axion-like particles Chern-Simons gravity coupling, such that gravitational waves can be produced directly from axion wave parametric resonance in the early universe after inflation. This axion gravity term is less constrained compared to the well-searched axion photon coupling and can provide a direct and efficient production channel for gravitational waves. Such stochastic gravitational waves can be detected by either space/ground-based gravitational wave detectors or pulsar timing arrays for a broad range of axion masses and decay constants.

    hep-phastro-ph.COgr-qcEPJC(2024)·11 citations
12. 12*

    Soft-overlap contribution to $B_c\to {\eta }_c$ form factors: diagrammatic resummation of double logarithms

    Guido Bell🇩🇪 · Philipp Böer🇩🇪 · Thorsten Feldmann🇩🇪 · Dennis Horstmann🇩🇪 · Vladyslav Shtabovenko🇩🇪

    Using diagrammatic resummation techniques, we investigate the double-logarithmic series of the "soft-overlap" contribution to $B_c\to {\eta }_c$ transition form factors at large hadronic recoil, assuming the scale hierarchy $m_b\gg m_c\gg {\Lambda }_{\mathrm{QCD}}$. In this case, the hadronic bound states can be treated in the non-relativistic approximation and the relevant hadronic matrix elements can be computed perturbatively. This setup defines one of the simplest examples to study the problem of endpoint singularities appearing in the factorization of exclusive $B$-decay amplitudes. We find that the leading double logarithms arise from a peculiar interplay of soft-quark "endpoint logarithms" from ladder diagrams with energy-ordered spectator-quark propagators, as well as standard Sudakov-type soft-gluon corrections. We elucidate the all-order systematics, and show that their resummation proceeds via a novel type of integral equations. The current status of the calculation, which includes all double logarithms in the Abelian limit, is reported.

    hep-phPoS(2024)·8 citations
13. 13*

    Corrected Calculation for the Non-local Solution to the g-2 Anomaly and Novel Results in Non-local QED

    Fayez Abu-Ajamieh🇮🇳 · Nobuchika Okada🇺🇸 · Sudhir K. Vempati🇮🇳

    We provide the corrected calculation of the muon g-2 in non-local QED previously done in the literature. In specific, we show the proper technique for calculating loops in non-local QED and use it to find the form factors F1(q1) and F2(q2) in non-local QED. We also utilize this technique to calculate some novel results in non-local QED, including calculating the correction to the photon self-energy, the modification to the classical Coulomb potential, the modification to the energy levels of the hydrogen atom, and the contribution to the Lamb shift. We also discuss charge dequantization through non-locality, and show that the experimental bounds on the electric charge on Dirac neutrinos, translate into strong flavor-dependent bounds on the scale on non-locality that range between 10^5 - 10^10 TeV. We also discuss the inconsistencies of unrenormalized non-local Quantum Field Theories (QFTs) and the need for renormalizing them, even when they are free from UV divergences.

    hep-phJHEP(2024)·11 citations
14. 14*

    Thermoelectric response of a hot and weakly magnetized anisotropic QCD medium

    Salman Ahamad Khan🇮🇳 · Debarshi Dey🇮🇳 · Binoy krishna Patra🇮🇳

    We have studied the Seebeck and Nernst coefficients of a weakly magnetized hot QCD medium having a weak momentum anisotropy within the kinetic theory approach. The thermal medium effects have been incorporated in the framework of a quasi-particle model where the medium dependent mass of the quark has been calculated using perturbative thermal QCD in the presence of a weak magnetic field which leads to different masses for the left ($L$) and right ($R$) handed chiral quark modes. We have found that the Seebeck and Nernst coefficient magnitudes for the individual quark flavors as well as for the composite medium are decreasing functions of temperature and decreasing functions of anisotropy strength. The Nernst coefficient magnitudes are about an order of magnitude smaller than their Seebeck counterparts, indicating the Seebeck effect constitutes a stronger response than the Nernst effect. The average percentage change corresponding to switching between quasiparticle modes ($L\to R$ or $R\to L$) is an order of magnitude smaller for Nernst coefficients, compared to the Seebeck coefficients.

    hep-phnucl-thPRC(2024)·5 citations
15. 15*

    Tuning Pythia for Forward Physics Experiments

    Max Fieg🇺🇸 · Felix Kling🇩🇪 · Holger Schulz🇬🇧 · Torbjörn Sjöstrand🇸🇪

    Event generators like Pythia play an important role in physics studies at the Large Hadron Collider (LHC). While they make accurate predictions in the central region, i.e. at pseudorapidities $\eta <5$, a disagreement between Pythia and measurements in the forward region, $\eta >7$, has been observed. We introduce a dedicated forward physics tune for the Pythia event generator to be used for forward physics studies at the LHC, which uses a more flexible modelling of beam remnant hadronization and is tuned to available particle spectra measured by LHCf. Furthermore, we provide an uncertainty estimate on the new tune in a data-driven way which can be used as a means of flux uncertainty for future forward physics studies. We demonstrate an application of our tune by showing the updated neutrino and dark photon spectra at the FASER experiment.

    hep-phPRD(2024)·57 citations
16. 16*

    Generalized Ray Tracing for Axions in Astrophysical Plasmas

    J. I. McDonald🇧🇪 · S. J. Witte🇳🇱

    Ray tracing plays a vital role in black hole imaging, modeling the emission mechanisms of pulsars, and deriving signatures from physics beyond the Standard Model. In this work we focus on one specific application of ray tracing, namely, predicting radio signals generated from the resonant conversion of axion dark matter in the strongly magnetized plasma surrounding neutron stars. The production and propagation of low-energy photons in these environments are sensitive to both the anisotropic response of the background plasma and curved spacetime; here, we employ a fully covariant framework capable of treating both effects. We implement this both via forward and backward ray tracing. In forward ray tracing, photons are sampled at the point of emission and propagated to infinity, whilst in the backward-tracing approach, photons are traced backwards from an image plane to the point of production. We explore various approximations adopted in prior work, quantifying the importance of gravity, plasma anisotropy, the neutron star mass and radius, and imposing the proper kinematic matching of the resonance. Finally, using a more realistic model for the charge distribution of magnetar magnetospheres, we revisit the sensitivity of current and future radio and sub-mm telescopes to spectral lines emanating from the Galactic Center Magnetar, showing such observations may extend sensitivity to axion masses $m_a\sim \mathcal{O}(\mathrm{few})\times 10^{-3}$ eV, potentially even probing parameter space of the QCD axion.

    hep-phastro-ph.COastro-ph.HEPRD(2023)·33 citations
17. 17*

    Dark Matter-Induced Baryonic Feedback in Galaxies

    Javier F. Acevedo🇺🇸 · Haipeng An🇨🇳 · Yilda Boukhtouchen🇨🇦 · Joseph Bramante🇨🇦 · Mark Richardson🇨🇦 · Lucy Sansom🇨🇦

    We demonstrate that non-gravitational interactions between dark matter and baryonic matter can affect structural properties of galaxies. Detailed galaxy simulations and analytic estimates demonstrate that dark matter which collects inside white dwarf stars and ignites Type Ia supernovae can substantially alter star formation, stellar feedback, and the halo density profile through a dark matter-induced baryonic feedback process, distinct from usual supernova feedback in galaxies.

    hep-phastro-ph.COastro-ph.GAPRD(2024)·13 citations
18. 18*

    Dark I-Love-Q

    Jing-Yi Wu🇨🇳 · Wei Li🇨🇳 · Xin-Han Huang🇨🇳 · Kilar Zhang🇨🇳

    For neutron stars, there exist universal relations insensitive to the equation of states, the so called I-Love-Q relations, which show the connections among the moment of inertia, tidal Love number and quadrupole moment. In this paper, we show that these relations also apply to dark stars, bosonic or fermionic. The relations can be extended to higher ranges of the variables, clarifying the deviations for dark stars in the literature, as those curves all approximate the ones generated by a polytropic equation of state, when taking the low density (pressure) limit. Besides, we find that for equation of states with scaling symmetries, the I-Love-Q curves do not change when adjusting the scaling parameters.

    ↳ astro-ph.HEgr-qchep-phhep-thEPJC(2025)·6 citations
19. 19*

    Form factors for the charm-baryon semileptonic decay ${\Xi }_c\to \Xi \ell \nu$ from domain-wall lattice QCD

    Callum Farrell🇺🇸 · Stefan Meinel🇺🇸

    Recent experimental progress measuring the branching fractions of the heavy-baryon semileptonic decays ${\Xi }_c\to \Xi \ell \nu$ has stimulated theoretical interest and motivates precise lattice calculations of the form factors. Here we present such a calculation using domain-wall fermions for the up, down, and strange quarks, and an anisotropic clover action for the charm quark. We use four ensembles generated by the RBC and UKQCD collaborations, with lattice spacings between 0.111 and 0.073 fm and pion masses ranging from 420 to 230 MeV. Our preliminary results for the form factors are larger in magnitude than previous lattice results.

    ↳ hep-lathep-phPoS(2024)·6 citations
20. 20*

    Chemical potential (in)dependence of hadron scatterings in the hadronic phase of QCD-like theories and its applications

    Kotaro Murakami🇯🇵 · Etsuko Itou🇯🇵 · Kei Iida🇯🇵

    We formulate a method for calculating the hadron-hadron scattering amplitudes at nonzero chemical potential ($\mu$) in the hadronic phase at zero temperature, where the baryon number symmetry remains to be violated. Although it is widely believed that the physical quantities do not change even if we turn on a small $\mu$ at zero temperature, the shape of correlation functions for a single hadron depends on $\mu$. Then, the dispersion relation of the single hadron is modified to $E(\mathbf{p},\mu )=\sqrt{{\mathbf{p}}^2+m^2}-\mu n_O$. Here, $m$ and $n_O$ denote the hadron mass at $\mu =0$ and the quantum number, respectively. From this relation, it is possible that the effective mass of the hadron depends on $\mu$. We extend the HAL QCD method at $\mu =0$ to the case of $\mu \ne 0$, which allows us to extract the scattering phase shifts via the interaction potential. We have found that the interaction potential can depend on $\mu$ only through the effective mass while the scattering phase shifts, obtained by solving the Schrödinger equation with the interaction potential, are independent of $\mu$. We also numerically analyze the S-wave scatterings of two pions with isospin $I=2$ and two scalar diquarks within the framework of QC${}_2$D at nonzero quark chemical potential. While the lattice is not exactly set to zero temperature, the $\mu$-independence can be observed. Furthermore, we improve the results for the S-wave scatterings of two hadrons obtained above by taking the $\mu$-independence for granted. Thanks to the asymmetric property of the correlation functions for diquarks at $\mu \ne 0$, we can access a long-$\tau$ regime and can reduce the systematic error coming from inelastic contributions.

    ↳ hep-lathep-phnucl-thJHEP(2024)·8 citations
21. 21*

    Detecting Gravitationally Interacting Dark Matter with Quantum Interference

    Alejandro Perez🇫🇷 · Carlo Rovelli🇫🇷 · Marios Christodoulou🇦🇹

    In spite or the large astronomical evidence for its existence, the nature of dark matter remains enigmatic. Particles that interact only, or almost only, gravitationally, in particular with masses around the Planck mass -- the fundamental scale in quantum gravity, are intriguing candidates. Here we show that there is a theoretical possibility to directly detect such particles using highly sensitive gravity-mediated quantum phase shifts. In particular, we consider a protocol utilizing Josephson junctions.

    ↳ gr-qcastro-ph.COhep-phquant-phPRL(2024)·16 citations
22. 22*

    Fast Likelihood-free Reconstruction of Gravitational Wave Backgrounds

    Androniki Dimitriou🇪🇸 · Daniel G. Figueroa🇪🇸 · Bryan Zaldivar🇪🇸

    We apply state-of-the-art, likelihood-free statistical inference (machine-learning-based) techniques for reconstructing the spectral shape of a gravitational wave background (GWB). We focus on the reconstruction of an arbitrarily shaped signal by the LISA detector, but the method can be easily extended to either template-dependent signals, or to other detectors, as long as a characterisation of the instrumental noise is available. As proof of the technique, we quantify the ability of LISA to reconstruct signals of arbitrary spectral shape ($blind$ reconstruction), considering a diversity of frequency profiles, and including astrophysical backgrounds in some cases. As a teaser of how the method can reconstruct signals characterised by a parameter-dependent template ($template$ reconstruction), we present a dedicated study for power-law signals. While our technique has several advantages with respect to traditional MCMC methods, we validate it with the latter for concrete cases. This work opens the door for both fast and accurate Bayesian parameter estimation of GWBs, with essentially no computational overhead during the inference step. Our set of tools are integrated into the package $\mathtt{GWBackFinder}$, which is publicly available in https://github.com/AndronikiDimitriou/GWBackFinder.

    ↳ astro-ph.COgr-qchep-phJCAP(2024)·17 citations
23. 23*

    Frequency-scanning considerations in axionlike dark matter spin-precession experiments

    Yuzhe Zhang · Deniz Aybas Tumturk · Hendrik Bekker · Dmitry Budker · Derek F. Jackson Kimball · Alexander O. Sushkov · Arne Wickenbrock

    Galactic dark matter may consist of axionlike particles (ALPs) that can be described as an "ultralight bosonic field" oscillating at the ALP Compton frequency. The ALP field can be searched for using nuclear magnetic resonance (NMR), where resonant precession of spins of a polarized sample can be sensitively detected. The ALP mass to which the experiment is sensitive is scanned by sweeping the bias magnetic field. The scanning either results in detection of ALP dark matter or rules out ALP dark matter with sufficiently strong couplings to nuclear spins over the range of ALP masses corresponding to the covered span of Larmor frequencies. In this work, scanning strategies are analyzed with the goal of optimizing the parameter-space coverage via a proper choice of experimental parameters (e.g., the effective transverse relaxation time).

    ↳ physics.atom-phhep-phAnnalen Phys.(2024)·6 citations
24. 24*

    Statistical anisotropy of primordial gravitational waves from generalized $\delta N$ formalism

    Takahiro Tanaka🇯🇵 · Yuko Urakawa🇯🇵

    In this letter, we demonstrate how to use the generalized $\delta N$ formalism, which enables us to compute the evolution of all the large scale fluctuations, including gravitational waves, solely by solving the evolution of the background homogeneous Universe. Using the Noether charge density, we derive an analytic formula which describes the mapping between the fluctuations at the horizon crossing and the sourced gravitational waves at the end of inflation. This formula can apply also to an inflation model with an anisotropic background. Using this formula, we discuss the condition for the non-vanishing linear polarization and the qualitative difference between single- and multi-gauge field models.

    ↳ gr-qcastro-ph.COhep-phhep-thPRL(2024)·11 citations
25. 25*

    From Hubble to Bubble

    Maciej Kierkla🇵🇱 · Giorgio Laverda🇵🇹 · Marek Lewicki🇵🇱 · Andreas Mantziris🇵🇱 · Matteo Piani🇵🇹 · Javier Rubio🇪🇸 · Mateusz Zych🇵🇱

    The detection of a stochastic Gravitational Wave (GW) background sourced by a cosmological phase transition would allow us to see the early Universe from a completely new perspective, illuminating aspects of Beyond the Standard Model (BSM) physics and inflationary cosmology. In this study, we investigate whether the evolution of the scalar potential of a minimal SM extension after inflation can lead to a strong first-order phase transition. In particular, we focus on a BSM spectator scalar field that is non-minimally coupled to gravity and has a dynamical double-well potential. As inflation ends, the potential barrier diminishes due to the evolution of the curvature scalar. Therefore, a phase transition can proceed through the nucleation of true-vacuum bubbles that collide as they fill the Universe and produce GWs. We consider high and low scales of inflation, while also taking into account a kination period between inflation and the onset of radiation domination. With this prescription, we showcase a proof-of-concept study of a new triggering mechanism for BSM phase transitions in the early Universe, whose GW signatures could potentially be probed with future detectors.

    ↳ astro-ph.COgr-qchep-phJHEP(2023)·18 citations
26. 26*

    What can galaxy shapes tell us about physics beyond the standard model?

    Oliver H. E. Philcox🇺🇸 · Morgane J. König🇺🇸 · Stephon Alexander🇺🇸 · David N. Spergel🇺🇸

    The shapes of galaxies trace scalar physics in the late-Universe through the large-scale gravitational potential. Are they also sensitive to higher-spin physics? We present a general study into the observational consequences of vector and tensor modes in the early and late Universe, through the statistics of cosmic shear and its higher-order generalization, flexion. Higher-spin contributions arise from both gravitational lensing and intrinsic alignments, and we give the leading-order correlators for each (some of which have been previously derived), in addition to their flat-sky limits. In particular, we find non-trivial sourcing of shear $EB$ and $BB$ spectra, depending on the parity properties of the source. We consider two sources of vector and tensor modes: scale-invariant primordial fluctuations and cosmic strings, forecasting the detectability of each for upcoming surveys. Shear is found to be a powerful probe of cosmic strings, primarily through the continual sourcing of vector modes; flexion adds little to the constraining power except on very small scales ($\ell \gtrsim 1000$), though it could be an intriguing probe of as-yet-unknown rank-three tensors or halo-scale physics. Such probes could be used to constrain new physics proposed to explain recent pulsar timing array observations.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1PRD(2024)·35 citations
27. 27*

    Trace Anomaly of Weyl Fermions via the Path Integral

    Rémy Larue🇫🇷 · Jérémie Quevillon🇫🇷 · Roman Zwicky🇬🇧

    We compute the trace, diffeomorphism and Lorentz anomalies of a free Weyl fermion in a gravitational background field by path integral methods. This is achieved by regularising the variation of the determinant of the Weyl operator building on earlier work by Leutwyler. The trace anomaly is found to be one half of the one of a Dirac fermion. Most importantly we establish that the potential parity-odd curvature term $R\tilde{R}$, corresponding to the Pontryagin density, vanishes. This is to the contrary of some recent findings in the literature which gave rise to a controversy. We verify, that the regularisation does not lead to (spurious) anomalies in the Lorentz and diffeomorphism symmetries. We argue that in $d=2(\text{mod }4)$ $P$- and $CP$-odd terms cannot appear and that for $d=4(\text{mod }4)$ they are absent at least at leading order.

    ↳ hep-thhep-phJHEP(2023)·20 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.