Thu·Mar 21, 2024Thursday·March 21, 2024

1. 01*

   Aligned Yet Large Dipoles: a SMEFT Study

   Quentin Bonnefoy🇺🇸 · Jonathan Kley🇩🇪 · Di Liu🇫🇷 · Alejo N. Rossia🇬🇧 · Chang-Yuan Yao🇨🇳

   We study a non-universal flavor scenario at the level of the Standard Model Effective Field Theory, according to which the matrix of Wilson coefficients $c_{uW}$ of an up-type electroweak quark dipole operator is aligned with the up-type Yukawa coupling. Such an alignment usually follows from the assumption of Minimal Flavor Violation (MFV), away from which we step by allowing the entries of $c_{uW}$ to be sizable along the first quark generations. A particular example, which we refer to as ``inverse hierarchy MFV", features Wilson coefficients inversely proportional to quark masses, and arises from BSM models respecting MFV and containing heavy fields that replicate the mass hierarchy of SM quarks. We then analyze the phenomenology driven by $c_{uW}$ at colliders and at lower-energy flavor experiments. We show that precision measurements of the process $pp\to Wh\to \gamma \gamma \ell \nu$ at FCC-$hh$ could set an upper bound on $|c_{uW}|\lesssim \mathcal{O}(10^{-2})(\Lambda /\mathrm{TeV}{)}^2$, with $\Lambda$ the cutoff of the effective field theory. This bound is an order of magnitude stronger than the existing LHC bounds. Moreover, we estimate that $Wh\to b\bar{b}\ell \nu$ at HL-LHC could also give competitive bounds. In the low-energy regime, we consider bounds arising from rare kaon decays, which turn out to be loose, $|c_{uW}^{11}|<\mathcal{O}(1)(\Lambda /\mathrm{TeV}{)}^2$. We finally demonstrate that our flavor and operator assumptions can be derived from a weakly-coupled UV model, which we choose to simultaneously illustrate the UV origin of inverse hierarchy MFV.

   hep-phhep-thJHEP(2024)·10 citations
2. 02*

   An improved calculation of the $D_{(s)}^{\ast }{D}_{(s)}V$ and $B_{(s)}^{\ast }{B}_{(s)}V$ couplings from light-cone sum rules

   Su-Ping Jin🇨🇳 · Hua-Yu Jiang🇨🇳

   We present an improved calculation of the $D_{(s)}^{\ast }{D}_{(s)}V$ and $B_{(s)}^{\ast }{B}_{(s)}V$ coupling constants, where $V$ denotes $\rho$, $K^{\ast }$, $\omega$, and $\varphi$ meson. These couplings govern the QCD long-distance dynamics in interactions between heavy pseudoscalar/vector mesons and light vector mesons. Our analysis is conducted within the framework of QCD light-cone sum rules (LCSRs) by utilizing the light-cone distribution amplitudes (LCDAs) of light vector mesons. By systematically incorporating the subleading power corrections and higher-twist contributions at leading order (LO) and including the next-to-leading order (NLO) corrections at leading power, we achieve enhanced accuracy in the light-cone operator product expansion (OPE) for the underlying correlation function. In assessing the reliability of the established LCSRs, we consider uncertainties arising from the choice of the quark-hadron duality region in the double dispersion relation. Building upon these improvements, we accomplish an optimized computation and analysis for the strong coupling constants $g_{H^{\ast }HV}$ which are used to extract the effective coupling $\lambda$ in the heavy meson chiral perturbation theory (HM$\chi$PT). Furthermore, we investigate the $SU(3)$ flavour symmetry breaking effects in detail and compare our sum rule calculations with previous studies in an exploratory way.

   hep-phEPJC(2024)·5 citations
3. 03*

   Revisiting shear stress tensor evolution: Non-resistive magnetohydrodynamics with momentum-dependent relaxation time

   Sunny Kumar Singh🇮🇳 · Manu Kurian🇺🇸 · Vinod Chandra🇮🇳

   This study aims to develop second-order relativistic viscous magnetohydrodynamics (MHD) derived from kinetic theory within an extended relaxation time approximation (momentum/energy dependent) for the collision kernel. The investigation involves a detailed examination of shear stress tensor evolution equations and associated transport coefficients. The Boltzmann equation is solved using a Chapman-Enskog-like gradient expansion for a charge-conserved conformal system, incorporating a momentum-dependent relaxation time. The derived relativistic non-resistive, viscous second-order MHD equations for the shear stress tensor reveal significant modifications in the coupling with dissipative charge current and magnetic field due to the momentum dependence of the relaxation time. By utilizing a power law parametrization to quantify the momentum dependence of the relaxation time, the anisotropic magnetic field-dependent shear coefficients in the Navier-Stokes limit have been investigated. The resulting viscous coefficients are seen to be sensitive to the momentum dependence of the relaxation time.

   hep-phnucl-thPRD(2024)·12 citations
4. 04*

   \alpha_s from DIS data with large $x$ resummations

   A.V. Kotikov🇷🇺 · B.G. Shaikhatdenov🇷🇺 · N.S. Korchagin🇨🇳 · P. Zhang🇨🇳

   The deep inelastic scattering data on the nucleon F_2 structure function, accumulated by BCDMS, SLAC and NMC collaborations in fixed-target experiments, are analyzed in the non-singlet approximation within the frameworks of both conventional \overline{\mathbf{MS}} scheme as well as those with resummations of logarithms at large Bjorken x values. The use of the latter is important because they greatly modify the values of the twist four corrections while leaving a strong coupling constant almost intact.

   hep-phJ.Phys.G(2025)·1 citation
5. 05*

   Improving probes of $hAA$ coupling in the Type-X two Higgs Doublet Model scenario: the crucial role of $\tau$-jet charge identification

   Biswarup Mukhopadhyaya🇮🇳 · Sirshendu Samanta🇮🇳 · Tousik Samui🇮🇳 · Ritesh K. Singh🇮🇳

   The exotic decay modes of the already discovered 125-GeV scalar into a pair of light pseudoscalars is a good probe of those new physics scenarios where such pseudoscalars exist. Searches in the mass region where the pseudoscalar ($A$) is lighter than 62.5 GeV have yielded null findings so far. No search has yet examined $m_A>62.5$ GeV where the cross section is suppressed by the off-shell pseudoscalar. We point out a possible enhancement of the sensitivity of probing $hAA$ coupling in the context of a Type-X two Higgs doublet model. We focus on $h\to A{A}^{(\ast )}\to 4\tau$, and select events with two same-sign $\tau$-jets along with a pair of same-sign leptons. This enables much more effective background elimination than in the erstwhile proposed channels. Taking two values of the $\tau \tau A$ coupling into account, we obtain limits on the $hAA$ coupling that can be probed at 2$\sigma$ and 3$\sigma$ significance, for $m_A$ ranging up to 85 GeV. For $m_A<62.5$ GeV, too, we find the probe through our suggested channel exhibits considerable improvement upon the usual $2\mu 2\tau$-based searches conducted at the LHC. Within this region, achieving the reach of ${\lambda }_{hAA}$ coupling at 3000 fb${}^{-1}$ luminosity using our strategy would require approximately $\sim$ 3.6$\times 10^5$ fb${}^{-1}$ luminosity using conventional $2\mu 2\tau$-based searches.

   hep-phhep-exPLB(2024)·1 citation
6. 06*

   Masses and decays of triply-heavy pentaquarks

   Chang-Le Liu🇵🇱 · Wen-Xuan Zhang🇨🇳 · Duojie Jia🇨🇳

   In this work, we study masses and decays of triply-heavy pentaquarks $QQQn\bar{n}(Q=b,c)$ in the unified MIT bag model. We construct the color-spin wave functions of the triply-heavy pentaquarks we address and use numerical variational method to compute all ground-state masses of these system. By excluding the scattering states in these configurations, we compute the decay width ratios of each decay channels relative to the maximum width for the compact pentaquark states, obtaining main decay modes of the triply-heavy pentaquark systems.

   hep-phCPC(2024)·6 citations
7. 07*

   Novel imprint of a dark photon from the 3-3-1-1 model

   Doan Minh Luong🇻🇳 · Phung Van Dong🇻🇳 · Nguyen Huy Thao🇻🇳

   We investigate a dark photon that arises from the UV model based upon $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X\otimes U(1{)}_G$ (3-3-1-1) gauge symmetry, where the last three factors enlarge the electroweak symmetry encompassing electric charge $Q=T_3-1/\sqrt{3}{T}_8+X$ and dark charge $D=-2/\sqrt{3}{T}_8+G$. It is well-established that this model addresses the questions of family number, neutrino mass, and dark matter. It is shown in this work that if the 3-3-1-1 breaking scale is much bigger than the dark charge breaking scale, the relevant dark gauge boson $Z^{\prime }$ is uniquely imprinted at TeV, avoiding dangerous FCNC processes, obeying precision electroweak measurements, as well as contributing to collider phenomena, even if no kinetic mixing is presented. The dark matter observables are perhaps governed by the dark charge breaking Higgs field instead of the dark photon.

   hep-phCommun.in Phys.(2025)·2 citations
8. 08*

   Absence of strong CP violation

   Gerrit Schierholz🇩🇪

   Quantum Chromodynamics admits a CP-violating contribution to the action, the $\theta$ term, which is expected to give rise to a nonvanishing electric dipole moment of the neutron. Despite intensive search, no CP violations have been found in the strong interaction. This puzzle is referred to as the strong CP problem. There is evidence that CP is conserved in the confining theory, to the extent that color charges are totally screened for $\theta >0$ at large distances. It is not immediately obvious that this implies a vanishing dipole moment though. With this Letter I will close the gap. It is shown that in the infinite volume hadron correlation functions decouple from the topological charge, expressed in terms of the zero modes. The reason is that hadrons have a limited range of interaction, while the density of zero modes vanishes with the inverse root of the volume, thus reducing the probability of finding a zero mode in the vicinity to zero. This implies that CP is conserved in the strong interaction.

   hep-phhep-lathep-thnucl-ex+1J.Phys.G(2025)·18 citations
9. 09*

   Scalar Dark Matter and Stability of Higgs Vacuum within a Minimal SO(10) GUT Model

   Nilavjyoti Hazarika🇮🇳 · Paramita Deka🇮🇳 · Kalpana Bora🇮🇳

   In this work, we delve to investigate a feasible range of dark matter (DM) masses within a non-supersymmetric $SO(10)$ Grand Unified Theory (GUT) scalar dark matter model, in freeze-out scenario. This model includes a singlet scalar denoted as S and an inert doublet represented by $\varphi$. Being part of SO(10), the quantum numbers of DM particles are assigned and hence we know their nature. These fields are odd under a discrete $Z_2$ matter parity $(-1{)}^{3(B-L)}$. The dark matter with mass 300 $\le M_{DM}\le$ 1000 GeV emerges as a mixture of the $Z_2$-odd scalar singlet $S$ and the neutral element of the doublet $\varphi$, both residing within a \textbf{16}-dim scalar representation of $SO(10)$. In this work we consider a real scalar \textbf{S} belonging to \textbf{16} of SO(10) as DM. We also investigate the one-loop vacuum stability through the solution of Renormalization Group Equations (RGEs) for the model's parameters. Subsequently, we scrutinize the model's predictions within the confines of contemporary theoretical and experimental restrictions. In addition to achieving vacuum stability in the SO(10) framework, the DM mass is found to lie in the previously unaddressed (theoretically) intermediate mass region of 300$⩽$ MDM $⩽$ 1000 GeV which also adheres to many current phenomenological constraints, like recent direct experimental bounds from XENON1T, indirect detection bounds from Fermi-LAT experiment, Higgs invisible decay and Electroweak Precision Test. The stability of the electroweak vacuum is seen to be present up to the Planck scale. These model predictions possess the potential for future validation through dark matter search experiments, as they are testable in future DM search experiments, along with the added feature that the model is a part of an elegant grand unified theory.

   hep-ph0 citations
10. 10*

    Unveiling the Composition of the Single-Charm Molecular Pentaquarks: Insights from Radiative Decay and Magnetic Moment

    Fu-Lai Wang🇨🇳 · Si-Qiang Luo🇨🇳 · Xiang Liu🇨🇳

    In order to unravel the composition of the isoscalar $DN$, $D^{\ast }N$, $D_{1}N$, and $D_2^{\ast }N$ molecular pentaquarks, we carry out a systematic investigation of their M1 and E1 radiative decays and magnetic moment properties. Using the constituent quark model and taking into account the $S$-$D$ wave mixing effect and the coupled channel effect, our analysis yields numerical results indicating that the M1 and E1 radiative decays and the magnetic moment properties of these molecular pentaquarks provide some insights into their inner structures. These results can provide crucial clues for distinguishing their spin-parity quantum numbers and configurations in experimental studies. In addition, we highlight the importance of the electromagnetic properties as key observables for elucidating the inner structures of the observed ${\Lambda }_c^{+}(2940)$ and ${\Lambda }_c^{+}(2910)$. We hope that these findings can inspire our experimental colleagues to further explore the family of the single-charm molecular pentaquarks and to investigate the inner structures of the ${\Lambda }_c^{+}(2940)$ and ${\Lambda }_c^{+}(2910)$ in future studies.

    hep-phEPJC(2025)·6 citations
11. 11*

    Hydrodynamic description of direct photon spectra and elliptic flow in Pb+Pb collisions at LHC

    Sándor Lökös🇵🇱 · Gábor Kasza🇭🇺

    In high energy heavy ion collisions a new state of matter, the strongly coupled quark gluon plasma is formed that exhibits the similar properties as our Universe had just a couple of microseconds after the Big Bang, hence such collisions are usually referred as Little Bangs. Subsequent investigations showed that the created medium is a nearly perfect fluid whose time evolution can be described by hydrodynamic models. The distribution of the hadrons that are created in the freeze-out after a rapid expansion carry information about the final state. On the other hand, with penetrating probes, e.g., with direct photons, one can model the time evolution of the quark gluon plasma. In this paper, we present a hydrodynamic model that was inspired by an analytical solution of relativistic hydrodynamics, calculate the invariant transverse momentum spectrum and the elliptic flow of direct photons and compare our results to LHC ALICE data to obtain the value of the model parameters. Based on the the results we give an estimation for the initial temperature of the plasma.

    hep-phEPJA(2025)·1 citation
12. 12*

    The electric dipole moment in a model for neutrino mass, dark matter and baryon asymmetry of the Universe

    Kazuki Enomoto🇰🇷 · Shinya Kanemura🇯🇵 · Sora Taniguchi🇯🇵

    The electric dipole moment is examined in a three-loop neutrino mass model with dark matter originally proposed in Aoki et al. [Phys. Rev. Lett. 102, 051805 (2009)]. The model contains a $CP$-violating phase in the Higgs potential which plays an important role in electroweak baryogenesis and is thus expected to explain the baryon asymmetry of the Universe simultaneously. However, such a $CP$-violating phase is severely constrained by the measurements of the electron electric dipole moment (eEDM), and a suppression mechanism for the eEDM is necessary to explain the observed baryon asymmetry while avoiding the constraint. In this paper, we examine neutrino mass, lepton-flavor-violating processes, dark matter, and the eEDM in the model. We show that the eEDM can be suppressed by destructive interference between the $CP$-violating phases in the Higgs sector and the dark sector with large $CP$-violating phases. We propose some benchmark scenarios including $O(1)$ $CP$-violating phases where tiny neutrino mass and dark matter can be explained while avoiding all current experimental and theoretical constraints. These $CP$-violating phases are expected to be large enough to generate the observed baryon asymmetry in the electroweak baryogenesis scenario.

    hep-phJHEP(2025)·5 citations
13. 13*

    Saturation and fluctuations in the proton wavefunction at large momentum transfers in exclusive diffraction at HERA

    Arjun Kumar🇮🇳 · Tobias Toll🇮🇳

    We present a model of proton geometry where the number and size of gluon density hotspots in the proton's thickness function evolves with the resolution scale of the event given by the Mandelstam $t$ variable in exclusive diffractive $ep$ collisions. We use the impact-parameter dependent saturation dipole model bSat/IPSat, as well as its linearised (non-saturated) version bNonSat. In the latter the proton thickness has a clear interpretation as a thickness and in the former it is directly related to the saturation scale. The resulting phenomenological model for the splitting of hotspots, making full use of earlier experimental and phenomenological studies, is able to describe the entire incoherent $t$-spectrum for $|t|>1.1$GeV${}^2$ with a single phenomenological parameter. We use the previously suggested hotspot model as an initial condition for our evolution. The resulting model is a resolution scale-evolution in the same vein as a parton shower.The incoherent cross section is directly proportional to geometrical fluctuations in the proton's inital state. The hotspot evolution give rise to several kinds of event-by-event fluctuations such as in the hotspot number, width and normalization, and saturation scale fluctuations is a direct effect of these. A natural consequence of our resolution based evolution is that the hotspots obtain an effective repulsion. We use our hotspot evolution model to investigate saturation scale effects in the $t$-spectrum, and found that HERA data is not sensitive to this physics.

    hep-ph5 citations
14. 14*

    Unsupervised and lightly supervised learning in particle physics

    Jai Bardhan🇮🇳 · Tanumoy Mandal🇮🇳 · Subhadip Mitra🇮🇳 · Cyrin Neeraj🇮🇳 · Monalisa Patra🇮🇳

    We review the main applications of machine learning models that are not fully supervised in particle physics, i.e., clustering, anomaly detection, detector simulation, and unfolding. Unsupervised methods are ideal for anomaly detection tasks -- machine learning models can be trained on background data to identify deviations if we model the background data precisely. The learning can also be partially unsupervised when we can provide some information about the anomalies at the data level. Generative models are useful in speeding up detector simulations -- they can mimic the computationally intensive task without large resources. They can also efficiently map detector-level data to parton-level data (i.e., data unfolding). In this review, we focus on interesting ideas and connections and briefly overview the underlying techniques wherever necessary.

    hep-phhep-exEur.Phys.J.ST(2024)·8 citations
15. 15*

    Locally finite two-loop amplitudes for electroweak production through gluon fusion

    Charalampos Anastasiou🇨🇭 · Julia Karlen🇨🇭 · George Sterman🇺🇸 · Aniruddha Venkata🇺🇸

    The computation of two-loop amplitudes for the production of multiple Higgs and electroweak gauge bosons via gluon fusion with exact dependence on quark masses relies primarily on numerical methods. We propose a framework that enables their numerical evaluation in momentum space. The method is inspired by the factorization of infrared divergences in QCD scattering amplitudes. It extends techniques introduced for electroweak gauge boson production from quark-antiquark annihilation to processes with external gluons. By combining diagrammatic integrands, we make use of local cancellations between diagrams that automatically eliminate most non-factoring infrared singularities. With a limited number of counterterms, we then derive two-loop integrands for which all soft and collinear singularities factorize locally. We hope that the local subtraction techniques presented in this article will play a useful role in extending the local factorization formalism to two-loop amplitudes for arbitrary processes.

    hep-phhep-thJHEP(2024)·22 citations
16. 16*

    Gravitational Wave Probe of Planck-scale Physics After Inflation

    Weiyu Hu🇨🇳 · Kazunori Nakayama🇯🇵 · Volodymyr Takhistov🇯🇵 · Yong Tang🇨🇳

    Particle decays are always accompanied by the emission of graviton quanta of gravity through bremsstrahlung processes. However, the corresponding branching ratio is suppressed by the square of the ratio of particle's mass to the Planck scale. The resulting present abundance of gravitational waves (GWs), composed of gravitons, is analogously suppressed. We show that superheavy particles, as heavy as the Planck scale, can be naturally produced during the post-inflationary reheating stage in the early Universe and their decays yield dramatic amounts of GWs over broad frequency range. GW observations could hence directly probe Planck-scale physics, notoriously challenging to explore.

    hep-phastro-ph.COastro-ph.HEhep-exPLB(2024)·29 citations
17. 17*

    Continuous Gravitational Waves: A New Window to Look for Heavy Non-annihilating Dark Matter

    Sulagna Bhattacharya🇮🇳 · Andrew L. Miller🇳🇱 · Anupam Ray🇺🇸

    Sun-like stars can transmute into comparable mass black holes by steadily accumulating heavy non-annihilating dark matter particles over the course of their lives. If such stars form in binary systems, they could give rise to quasi-monochromatic, persistent gravitational waves, commonly known as continuous gravitational waves, as they inspiral toward one another. We demonstrate that next-generation space-based detectors, e.g., Laser Interferometer Space Antenna (LISA) and Big Bang Observer (BBO), can provide novel constraints on dark matter parameters (dark matter mass and its interaction cross-section with the nucleons) by probing gravitational waves from transmuted Sun-like stars that are in close binaries. Our projected constraints depend on several astrophysical uncertainties, nevertheless, are competitive with the existing constraints obtained from cosmological measurements as well as terrestrial direct searches, demonstrating a notable science-case for these space-based gravitational wave detectors as probes of particle dark matter.

    hep-phastro-ph.COastro-ph.SRPRD(2024)·30 citations
18. 18*

    Signatures of Light New Particles in $B\to K^{(\ast )}{E}_{\mathrm{miss}}$

    Patrick D. Bolton🇸🇮 · Svjetlana Fajfer🇸🇮 · Jernej F. Kamenik🇸🇮 · Martín Novoa-Brunet🇪🇸

    The recent Belle II observation of $B\to K{E}_{\mathrm{miss}}$ challenges theoretical interpretations in terms of Standard Model neutrino final states. Instead, we consider new physics scenarios where up to two new light-invisible particles of spin 0 up to 3/2 are present in the final state. We identify viable scenarios by reconstructing the (binned) likelihoods of the relevant $B\to K^{(\ast )}{E}_{\mathrm{miss}}$ and also $B_s\to E_{\mathrm{miss}}$ experimental analyses and present preferred regions of couplings and masses. In particular, we find that the current data prefers two-body decay kinematics involving the emission of a single massive scalar or a vector particle, or alternatively, three-body decays involving pairs of massive scalars or spin 1/2 fermions. When applicable, we compare our findings with existing literature and briefly discuss some model-building implications.

    hep-phPRD(2024)·55 citations
19. 19*

    Kaluza-Klein Schwinger effect

    Yusuke Yamada🇯🇵

    We show that electric fields in compactified spaces may produce Kaluza-Klein (KK) particles even when the energy of electric fields is smaller than KK scale. As an illustrating example, we consider a charged massless complex scalar coupled to U(1) gauge theory in ${\mathbb{R}}^{1,3}\times {\mathbb{S}}^1$ and discuss the effect of background gauge potential along a compact direction. The electric field produces the charged Kaluza-Klein particle non-perturbatively, which we call KK Schwinger effect. We quantitatively show that KK modes can be produced even when the electric field energy is much below the KK scale. The mechanism is rather general and similar phenomena would occur in any compactification models when a gauge potential along compact direction evolves in time and experiences large enough field excursion. We also discuss the subtlety of four dimensional effective theory truncated by KK modes at an initial time, when the electric field is turned on.

    ↳ hep-thhep-phPTEP(2024)·4 citations
20. 20*

    Primordial Black Holes from Effective Field Theory of Stochastic Single Field Inflation at NNNLO

    Sayantan Choudhury🇮🇳 · Ahaskar Karde🇮🇳 · Pankaj Padiyar🇮🇳 · M. Sami🇮🇳

    We present a study of the Effective Field Theory (EFT) generalization of stochastic inflation in a model-independent single-field framework and its impact on primordial black hole (PBH) formation. We show how the Langevin equations for the "soft" modes in quasi de Sitter background is described by the Infra-Red (IR) contributions of scalar perturbations, and the subsequent Fokker-Planck equation driving the probability distribution for the stochastic duration $\mathcal{N}$, significantly modify in the present EFT picture. An explicit perturbative analysis of the distribution function by implementing the stochastic-$\delta N$ formalism is performed up to the next-to-next-to-next-to-leading order (NNNLO) for both the classical-drift and quantum-diffusion dominated regimes. In the drift-dominated limit, we perturbatively analyse the local non-Gaussianity parameters $(f_{\mathrm{NL}},g_{\mathrm{NL}},{\tau }_{\mathrm{NL}})$ with the EFT-induced modifications. In the diffusion-dominated limit, we numerically compute the probability distribution featuring exponential tails at each order of perturbative treatment.

    ↳ astro-ph.COcond-mat.stat-mechgr-qchep-ph+1EPJC(2025)·34 citations
21. 21*

    A novel PBH production mechanism from non-Abelian gauge fields during inflation

    Ema Dimastrogiovanni🇳🇱 · Matteo Fasiello🇪🇸 · Alexandros Papageorgiou🇪🇸

    We consider the case of axion-like particles (ALPs) during inflation. When coupled to a non-Abelian gauge sector via a Chern-Simons term, ALPs support an intriguing, testable, phenomenology with very distinctive features including chiral primordial gravitational waves. For sufficiently small values of the gauge vev and coupling, scalar perturbations in the gauge sector exhibit a known instability. We harness the power of such instability for primordial black hole (PBH) generation. In the case of an axion-inflaton, one is dynamically driven into a strong-backreaction regime that crosses the instability band thereby sourcing a peaked scalar spectrum leading to PBH production and the related scalar-induced gravitational waves. Remarkably, this dynamics is largely insensitive to the initial conditions and the shape of the potential, highlighting the universal nature of the sourcing mechanism. In the case of spectator ALPs one can identify the parameter space that sets off the strong backreaction regime and the ensuing features. We show that spectator ALP models may also access the scalar instability region without triggering strong backreaction.

    ↳ astro-ph.COhep-phPRD(2024)·24 citations
22. 22*

    The $\mathrm{SU}(3)$ twisted gradient flow strong coupling without topological freezing

    Claudio Bonanno🇪🇸 · Jorge Luis Dasilva Golán🇺🇸 · Massimo D'Elia🇮🇹 · Margarita García Pérez🇪🇸 · Andrea Giorgieri🇮🇹

    We investigate the role of topology on the lattice determination of the $\mathrm{SU}(3)$ strong coupling renormalized via gradient flow. To deal with the topological freezing of standard local algorithms, the definition of the coupling is usually projected onto the zero topological sector. However, it is not obvious that this definition is not biased by the loss of ergodicity. We instead avoid the topological freezing using a novel algorithm, the Parallel Tempering on Boundary Conditions. The comparison with a standard algorithm shows that, even in the case where the latter is severely frozen, one obtains the same projected coupling. Moreover, we show that the two definitions of the coupling, projected and non-projected, lead to the same flow of the renormalization scale. Our results imply that projecting the coupling does not affect the determination of the dynamically-generated scale of the theory $\Lambda$, as obtained through the step-scaling method.

    ↳ hep-lathep-phhep-thEPJC(2024)·15 citations
23. 23*

    High-cadence monitoring of the emission properties of magnetar XTE J1810-197 with the Stockert radio telescope

    Marlon L. Bause · Wolfgang Herrmann · Laura G. Spitler

    [...] We present a singlepulse search method, improving on commonly used neural network classifiers thanks to the filtering of radio frequency interference based on its spectral variance and the magnetar's rotation. With this approach, we were able to lower the signal to noise ratio (S/N) detection threshold from 8 to 5. This allowed us to find over 115,000 spiky single pulses - compared to 56,000 from the neutral network approach. Here, we present the temporal variation of the overall profile and single pulses. Two distinct phases of different single pulse activity can be identified: phase 1 from December 2018 to mid-2019, with a few single pulses per hour, and phase 2 from September 2020 with hundreds of single pulses per hour (with a comparable average flux density). We find that the single pulse properties and folded profile in phase 2 exhibit a change around mid-March 2021. Before this date, the folded profile consists of a single peak and single pulses, with fluences of up to 1000 Jyms and a single-peaked width distribution at around 10 ms. After mid-March 2021, the profile consists of a two peaks and the single pulse population shows a bimodal width distribution with a second peak at 1 ms and fluences of up to 500 Jyms. We also present asymmetries in the phase-resolved single pulse width distributions beginning to appear in 2020, where the pulses arriving earlier in the rotational phase appear wider than those appearing later. This asymmetry persists despite the temporal evolution of the other single pulse and emission properties. We argue that a drift in the emission region in the magnetosphere may explain this observed behaviour. Additionally, we find that the fluence of the detected single pulses depends on the rotational phase and the highest fluence is found in the centre of the peaks in the profile. [...]

    ↳ astro-ph.HEastro-ph.SRhep-phAstron.Astrophys.(2024)·5 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.