Thu·Jun 20, 2024Thursday·June 20, 2024

1. 01*

   Echoes of Veltman criteria on the next-two-Higgs-doublet model

   Abdesslam Arhrib🇲🇦 · Rachid Benbrik🇲🇦 · Larbi Rahili🇲🇦 · Souad Semlali🇬🇧 · Bassim Taki🇲🇦

   We investigate how the Next-Two-Higgs Doublet Model extension (N2HDM) should look if we are to address the naturalness problem using dimensional regularization. In such a model, new Higgs states are predicted, namely: three CP-even $h_{1,2,3}$, one CP-odd $A$, and a pair of charged Higgs boson $H^{\pm }$. Our calculations of the overall quadratic divergences have been performed with full consistency with the latest data from the Large Hadron Collider (LHC) concerning the observed 125 GeV Higgs boson, alongside precision electroweak data tests and lower mass limits on charged Higgs boson. It is shown that the quadratically divergent quantum corrections ${\delta }_i$ (i=1,2,3) for the three CP-even Higgs bosons are controllably small, though hidden fine-tuning might still be required. This reveals a significant impact on the model parameter space, Higgs spectrum mass, and notably the singlet-doublet admixture.

   hep-phEPJC(2024)·4 citations
2. 02*

   PIPPIN: Generating variable length full events from partons

   Guillaume Quétant🇨🇭 · John Andrew Raine🇨🇭 · Matthew Leigh🇨🇭 · Debajyoti Sengupta🇨🇭 · Tobias Golling🇨🇭

   This paper presents a novel approach for directly generating full events at detector-level from parton-level information, leveraging cutting-edge machine learning techniques. To address the challenge of multiplicity variations between parton and reconstructed object spaces, we employ transformers, score-based models and normalizing flows. Our method tackles the inherent complexities of the stochastic transition between these two spaces and achieves remarkably accurate results. The combination of innovative techniques and the achieved accuracy demonstrates the potential of our approach in advancing the field and opens avenues for further exploration. This research contributes to the ongoing efforts in high-energy physics and generative modelling, providing a promising direction for enhanced precision in fast detector simulation.

   hep-phcs.LGhep-exstat.MLPRD(2024)·22 citations
3. 03*

   Pair creation in electric fields

   Christian Schubert🇲🇽

   Sauter-Schwinger pair creation in electromagnetic fields is a fundamental prediction of QED and one of the motivations for the present efforts in constructing super-strong lasers. I will give a historical review of the subject, and then focus on two recent developments. The first one is the worldline instanton formalism, a sophisticated version of the WKB approximation that makes it possible to calculate the pair creation rate for complicated field configurations. The second one is an adaptation of the Dirac-Heisenberg-Wigner formalism suitable for a detailed study of the formation of real particles in time and space.

   hep-phhep-thEPJ Web Conf.(2024)·2 citations
4. 04*

   Probing ALP Lepton Flavour Violation at $\mu$TRISTAN

   Lorenzo Calibbi🇨🇳 · Tong Li🇨🇳 · Lopamudra Mukherjee🇨🇳 · Yiming Yang🇨🇳

   Axion-like particles (ALPs) with lepton flavour violating (LFV) interactions are predicted within a wide range of flavoured ALP models. The proposed $\mu$TRISTAN high-energy $e^{-}{\mu }^{+}$ and ${\mu }^{+}{\mu }^{+}$ collider will provide a good opportunity to explore flavour physics in the charged lepton sector. In this work, based on a model-independent effective Lagrangian describing the ALP leptonic interactions, we investigate the potential of $\mu$TRISTAN to probe ALP LFV couplings. We analyse the testability of selected ALP production channels with potential sensitivity at $\mu$TRISTAN, considering different beams and collision energies, including $e^{-}{\mu }^{+}\to a\gamma$, $e^{-}{\mu }^{+}\to e^{-}{\tau }^{+}a$, ${\mu }^{+}{\mu }^{+}\to {\mu }^{+}{\tau }^{+}a$, and $e^{-}{\mu }^{+}\to {\tau }^{-}{\mu }^{+}a$. The produced ALP $a$ is either long-lived or can promptly decay to flavour violating or conserving charged lepton final states. In particular, combining the above LFV ALP production modes with a suitable LFV decay mode, one can identify signatures that are virtually free of Standard Model background. We show the resulting sensitivity of $\mu$TRISTAN to LFV ALP couplings and compare it with multiple low-energy leptonic constraints and the future improvements thereof. We find that $\mu$TRISTAN can be generally complementary to searches for low-energy LFV processes and measurements of the leptonic magnetic dipole moments and has the capability to explore unconstrained parameter space for ALP masses in the $\mathcal{O}(1)$ to $\mathcal{O}(100)$~GeV range. In the light ALP regime, however, the parameter space that $\mu$TRISTAN is sensitive to, has been already excluded by low-energy searches for LFV decays.

   hep-phhep-exPRD(2024)·29 citations
5. 05*

   Charm and Bottom Hadrons in Hot Hadronic Matter

   Santosh K. Das🇮🇳 · Juan M. Torres-Rincon🇪🇸 · Ralf Rapp🇺🇸

   Heavy quarks, and the hadrons containing them, are excellent probes of the QCD medium formed in high-energy heavy-ion collisions, as they provide essential information on the transport properties of the medium and how quarks color-neutralize into hadrons. Large theoretical and phenomenological efforts have been dedicated thus far to assess the diffusion of charm and bottom quarks in the quark-gluon plasma and their subsequent hadronization into heavy-flavor (HF) hadrons. However, the fireball formed in heavy-ion collisions also features an extended hadronic phase, and therefore any quantitative analysis of experimental observables needs to account for the rescattering of charm and bottom hadrons. This is further reinforced by the presence of a QCD cross-over transition and the notion that the interaction strength is maximal in the vicinity of the pseudo-critical temperature. We review existing approaches for evaluating the interactions of open HF hadrons in a hadronic heat bath and the pertinent results for scattering amplitudes, spectral functions and transport coefficients. While most of the work to date has focused on $D$-mesons, we also discuss excited states as well as HF baryons and the bottom sector. Both the HF hadro-chemistry and bottom observables will play a key role in future experimental measurements. We also conduct a survey of transport calculations in heavy-ion collisions that have included effects of hadronic HF diffusion and assess its impact on various observables.

   hep-phnucl-exnucl-thPhys.Rept.(2025)·32 citations
6. 06*

   Dimuon production in neutrino-nucleus collisions -- the SIDIS approach

   Ilkka Helenius🇫🇮 · Hannu Paukkunen🇫🇮 · Sami Yrjänheikki🇫🇮

   Dimuon production is in many global parton distribution function analyses calculated by assuming that it is proportional to inclusive charm production. As this assumption breaks down at next-to-leading order in the perturbative expansion, we present a direct calculation of dimuon production that does not require an external acceptance correction. Our calculation utilizes semi-inclusive deep inelastic scattering and a decay function fitted to experimental data. We find our calculation to be in good agreement with available experimental data. Here we also demonstrate that the acceptance correction depends on the used parton distribution and perturbative order.

   hep-phPoS(2025)·0 citations
7. 07*

   Charge distributions of pseudo-scalar and vector mesons from Dyson-Schwinger equations

   Y.-Z. Xu🇪🇸 · K. Raya🇪🇸 · J. Segovia🇪🇸 · J. Rodríguez-Quintero🇪🇸

   We combine the Dyson-Schwinger/Bethe-Salpeter equations framework with modern numerical reconstruction methods to derive the three-dimensional and transverse two-dimensional charge distribution of an array of ground-state pseudoscalar and vector mesons from their elastic electromagnetic form factor in the low-momentum region. The charge radii obtained by averaging over the reconstructed charge distributions have been checked to be consistent with those calculated from the slope of the elastic electromagnetic form factor at zero transferred momentum. The capability of the reconstruction procedure for capturing a reliable low-distance charge distribution is discussed and argued to work down to distances of around 0.1 fm, such that it might be potentially applied to extract, {\it e.g.}, mass densities from gravitational form factors.

   hep-phPRD(2024)·11 citations
8. 08*

   Leptogenesis assisted by scalar decays

   Jun-Yu Tong🇨🇳 · Zhao-Huan Yu🇨🇳 · Hong-Hao Zhang🇨🇳

   We present a pragmatic approach to lower down the mass scale of right-handed neutrinos in leptogenesis by introducing a scalar decaying to right-handed neutrinos. The key point of our proposal is that the out-of-equilibrium decays of the scalar provide an additional source for right-handed neutrinos and hence the lepton asymmetry. This mechanism works well at low temperatures when the washout of the generated lepton asymmetry is suppressed. Thus, the lepton asymmetry can be effectively produced despite the washout effect is strong or not. Through a comprehensive analysis, we demonstrate that such a scalar-assisted leptogenesis can typically decrease the viable right-handed neutrino mass scale by one to three orders of magnitude.

   hep-phJHEP(2025)·5 citations
9. 09*

   Resonances in the quark model

   Jean-Marc Richard🇫🇷 · Alfredo Valcarce🇪🇸 · Javier Vijande🇪🇸

   A discussion is presented of the estimates of the energy and width of resonances in constituent models, with focus on the tetraquark states containing heavy quarks.

   hep-phnucl-thFew Body Syst.(2024)·2 citations
10. 10*

    LQCD constrained magnetic field dependent coupling constant in an effective model

    Shijun Mao🇨🇳

    A magnetic field dependent coupling constant $G(eB)$ is investigated in the two-flavor magnetized NJL model. Based on LQCD results of the neutral (charged) pion mass spectra at vanishing temperature and finite magnetic field, we determine the $G(eB)=G^0(eB)$ ($G(eB)=G^{+}(eB)$) in the NJL model. $G^0(eB)$ and $G^{+}(eB)$ are both non-monotonic functions of magnetic fields, but they are different from each other. Furthermore, we calculate the pseudo-critical temperatures $T_{pc}(eB)$ of chiral restoration phase transition with $G^0(eB)$ and $G^{+}(eB)$ in the magnetized NJL model, respectively. The resulting $T_{pc}(eB)$ are non-monotonic functions of magnetic fields. In previous work, $G(eB)$ in the NJL model fitted from the chiral condensate or pseudo-critical temperature of LQCD simulations is a decreasing function of magnetic field. It can not explain the saturation behavior of mass spectra of neutral pion and decreasing behavior of mass spectra of charged pion with strong magnetic field. We conclude that a magnetic field dependent coupling constant $G(eB)$ in the NJL model can not simultaneously explain the reduction of pseudo-critical temperature of chiral restoration phase transition and the light meson mass spectra under external magnetic field.

    hep-phnucl-th0 citations
11. 11*

    Neutrino trident scattering at the LHC energy regime

    Reinaldo Francener🇧🇷 · Victor P. Goncalves🇧🇷 · Diego R. Gratieri🇧🇷

    The neutrino trident scattering process in neutrino - tungsten interactions at the LHC energy regime is investigated, and the cross-sections for different leptonic final states in coherent and incoherent interactions are estimated. Furthermore, the associated number of eventsat FASER$\nu$2 detector is estimated considering different predictions for the flux of incident neutrinos on the detector, based on distinct hadronic models for the particle production in $pp$ collisions at ultra-forward rapidities. Our results indicate that the observation of the neutrino trident process is, in principle, feasible at the Forward Physics Facility.

    hep-phhep-exEPJC(2024)·11 citations
12. 12*

    Working group 1 summary: $V_{ud}$, $V_{us}$, $V_{cd}$, $V_{cs}$ and semileptonic/leptonic $D$ decays

    Bipasha Chakraborty🇬🇧 · Alex Gilman🇬🇧 · Martin Hoferichter🇨🇭 · Michal Koval🇨🇿

    We summarize the program of working group 1 at the 12th Workshop on the CKM Unitarity Triangle, whose main subjects covered $V_{ud}$, $V_{us}$, and first-row unitarity as well as $V_{cd}$, $V_{cs}$, and (semi-)leptonic $D$ decays.

    hep-phhep-exhep-latnucl-ex+11 citation
13. 13*

    Neutrino Tomography of the Earth: the Earth Total Mass, Moment of Inertia and Hydrostatic Equilibrium Constraints

    S. T. Petcov🇮🇹

    We investigate the implications of the constraints following from the precise knowledge of the total Earth mass, $M_{\oplus }$, and moment of inertia, $I_{\oplus }$, and from the requirement that Earth be in hydrostatic equilibrium (EHE), in the neutrino tomography studies of the Earth density structure. In order to estimate the sensitivity of a given neutrino detector to possible deviations of the inner core (IC), outer core (OC), core (IC + OC) and mantle Earth densities from those obtained using geophysical and seismological data and described by the preliminary reference Earth model (PREM), in the statistical analyses performed within the neutrino tomography studies one typically varies the density of each of these structures. These variations, however, must respect the $M_{\oplus }$, $I_{\oplus }$ and EHE constraints. Working with PREM average densities we derive the $M_{\oplus }$, $I_{\oplus }$ and EHE constraints on the possible density variations when one approximates the Earth density structure with i) three layers - mantle, outer core and inner core, and ii) four layers - upper mantle, lower mantle, outer core and inner core. We get drastically different results in the two cases.

    hep-phEPJC(2024)·6 citations
14. 14*

    The next galactic supernova can uncover mass and couplings of particles decaying to neutrinos

    Bernanda Telalovic🇩🇰 · Damiano F.G. Fiorillo🇩🇰 · Pablo Martínez-Miravé🇩🇰 · Edoardo Vitagliano🇮🇹 · Mauricio Bustamante🇩🇰

    Many particles predicted by extensions of the Standard Model feature interactions with neutrinos, e.g., Majoron-like bosons $\varphi$. If the mass of $\varphi$ is larger than about 10 keV, they can be produced abundantly in the core of the next galactic core-collapse supernova through neutrino coalescence, and leave it with energies of around 100 MeV. Their subsequent decay to high-energy neutrinos and anti-neutrinos provides a distinctive signature at Earth. Ongoing and planned neutrino and dark matter experiments allow us to reconstruct the energy, flavor, and time of arrival of these high-energy neutrinos. For the first time, we show that these measurements can help pinpointing the mass of $\varphi$ and its couplings to neutrinos of different flavor. Our results can be generalized in a straightforward manner to other hypothetical feebly interacting particles, like novel gauge bosons or heavy neutral leptons, that decay into neutrinos.

    hep-phastro-ph.HEJCAP(2024)·33 citations
15. 15*

    CMB Spectral Distortions: A Multimessenger Probe of the Primordial Universe

    Bryce Cyr🇬🇧

    The frequency spectrum of the cosmic microwave background (CMB) is a relatively untapped source of data which can allow us to peer beyond the surface of last scattering. Small deviations away from a perfect blackbody shape will encode valuable information about the state of the primordial Universe which may not be accessible by other means. Here, we briefly review some key science goals of CMB spectral distortions, with an emphasis on how future generations of experiments can be used in tandem with complementary observational probes to perform model discrimination of exotic physics scenarios. We focus here on synergies between spectral distortions, gravitational waves, and 21cm cosmology.

    ↳ astro-ph.COhep-ph1 citation
16. 16*

    Microscale torsion resonators for short-range gravity experiments

    J. Manley🇺🇸 · C. A. Condos🇺🇸 · S. Schlamminger🇺🇸 · J. R. Pratt🇺🇸 · D. J. Wilson🇺🇸 · W. A. Terrano🇺🇸

    Measuring gravitational interactions on sub-100-$\mu$m length scales offers a window into physics beyond the Standard Model. However, short-range gravity experiments are limited by the ability to position sufficiently massive objects to within small separation distances. Here we propose mass-loaded silicon nitride ribbons as a platform for testing the gravitational inverse square law at separations currently inaccessible with traditional torsion balances. These microscale torsion resonators benefit from low thermal noise due to strain-induced dissipation dilution while maintaining compact size (<100$\mu$g) to allow close approach. Considering an experiment combining a 40$\mu$g torsion resonator with a source mass of comparable size (130$\mu$g) at separations down to 25$\mu$m, and including limits from thermomechanical noise and systematic uncertainty, we predict these devices can set novel constraints on Yukawa interactions within the 1-100$\mu$m range.

    ↳ gr-qchep-phphysics.ins-detPRD(2024)·10 citations
17. 17*

    Mildly boosted dark matter annihilation and reconciling indirect galactic signals

    Steven J. Clark🇺🇸

    The galactic center excess is a possible non-gravitational observation of dark matter; however, the canonical dark matter model (thermal freeze-out) is in conflict with other gamma-ray observations, in particular those made of the Milky Way's satellite dwarf galaxies. Here we consider the effects of a two-component dark matter model which results in minimally boosted particles that must remain bound to their host galaxy in order to produce an observational signal. This leads to a signal that is heavily dependent on galactic scale and can help reconcile the differences in the galactic center and dwarf galaxy measurements under the dark matter paradigm.

    ↳ astro-ph.COastro-ph.HEhep-ph2 citations
18. 18*

    The Hanbury-Brown and Twiss effect in inflationary cosmological perturbations

    Gustavo Matheus Gauy🇧🇷 · Flavia Sobreira🇧🇷 · Giorgio Torrieri🇧🇷

    The simplest model of inflation is based around an inflaton field that starts in a coherent false vacuum state with a positive cosmological constant, rolls slowly to the true vacuum and relaxes to it via reheating. We examine whether the scale of the transition from coherence to chaoticity can be examined via the Hanbury-Brown and Twiss (HBT) effect, in parallel with analogous problems of heavy ion physics (the ``pion laser'' and the thermalizing glasma). We develop an ansatz which contains a definition of ''chaoticity'' which parallels that of the usual setups where HBT is used. However, we also discuss the differences between the inflationary setup and more mainstream uses of HBT and conclude that these are more significant than the similarities, making the use of the developed methodology uncertain.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2024)·1 citation
19. 19*

    Impacts of Black-Hole-Forming Supernova Explosions on the Diffuse Neutrino Background

    Ken'ichiro Nakazato🇯🇵 · Ryuichiro Akaho🇯🇵 · Yosuke Ashida🇺🇸 · Takuji Tsujimoto🇯🇵

    Flux spectrum, event rate, and experimental sensitivity are investigated for the diffuse supernova neutrino background (DSNB), which originates from past stellar collapses and is also known as a supernova relic neutrino background. For this purpose, the contribution of collapses that lead to successful supernova (SN) explosion and black hole (BH) formation simultaneously, which are suggested to be a non-negligible population from the perspective of Galactic chemical evolution, is taken into account. If the BH-forming SNe involve the matter fallback onto the protoneutron star for the long term, their total emitted neutrino energy becomes much larger than that of ordinary SNe and failed SNe (BH formation without explosion). Then, in the case of the normal mass hierarchy in neutrino oscillations and with half of all core-collapse SNe being BH-forming SNe, the expected event rate according to the current DSNB model is enhanced by up to a factor of two due to the BH-forming SNe. While substantial uncertainties exist regarding the duration of the matter fallback, which determines the total amount of emitted neutrinos, and the fraction of BH-forming SNe, the operation time required to detect the DSNB at Hyper-Kamiokande would be reduced by such contribution in any case.

    ↳ astro-ph.HEhep-phApJ(2024)·11 citations
20. 20*

    Gravitational Wave Birefringence from Fuzzy Dark Matter

    Da Huang🇨🇳 · Ze-Xuan Xiong🇨🇳 · Lei-Jian Wang🇨🇳

    Gravitational wave (GW) birefringence is a remarkable phenomenon that can be used to test the parity violation in gravity. By coupling the fuzzy dark matter (FDM) scalar to the gravitational Chern-Simons term, we explore the GW birefringence effects in the FDM background. In particular, in light of the highly oscillating granular FDM structure at the galactic scale, we are led to investigating the GW propagation in the Chern-Simons gravity over the general nontrivial scalar profile, which is a natural extension of previous studies on the homogeneous and isotropic configurations. As a result, it is found that GWs of both circularly polarized modes propagate in the straight line with the speed of light, and does not show any velocity birefringence. However, when considering the imaginary part of the dispersion relation, GWs exhibit the amplitude birefringence in which one circular polarization is enhanced while the other suppressed. Due to its local nature, the FDM-induced amplitude birefringence factor only depends on the GW frequency without any reliance on the GW propagating distance, which can be used to distinguish this signal from other birefringece mechanisms. More importantly, the birefringence shows a periodic time modulation with the period directly reflecting the FDM scalar mass, which is another smoking gun for testing this model. Finally, we also study the extra-galactic FDM contribution to the GW birefringence, which is shown to be suppressed by the cosmological DM density and thus subdominant compared with the galactic counterpart.

    ↳ gr-qcastro-ph.COhep-ph2 citations
21. 21*

    Neutron stars and Pulsar timing arrays as Axion giant gyroscopes

    Yiming Liu🇨🇳 · Jinneng Luo🇨🇳 · Sichun Sun🇨🇳

    We consider the three-dimensional rotating motions of neutron stars blown by the "axion wind". Neutron star precession and spin can change from the magnetic moment coupling to the oscillating axion background field, in analogy to the gyroscope motions with a driving force and the laboratory Nuclear Magnetic Resonance(NMR) detections of the axion. This effect modulates the pulse arrival time of the pulsar timing arrays. It shows up as a signal on the timing residual and two-point correlation function on the recent data of Nanograv and PPTA. The current measurement of PTAs can thus cast constraints on the axion-nucleon coupling as g_{ann} ~ 10^{-12}{GeV}^{-1}.

    ↳ astro-ph.COhep-phCPC(2026)·0 citations
22. 22*

    Energy dependence of particle production in Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 7.7-200 GeV using a multiphase transport model

    Krishan Gopal🇮🇳 · Chitrasen Jena🇮🇳 · Kishora Nayak🇮🇳

    In this study, we employ a multi-phase transport (AMPT) model to understand the production of ${\pi }^{\pm }$, $K^{\pm }$, $p$, $\overline{p}$, $K_s^0$, $\Lambda$, $\bar{\Lambda }$, and $\varphi$ in Au + Au collisions at $\sqrt{s_{NN}}=7.7$, $27$, $39$, $62.4$, and $200$ GeV. We have studied the energy dependence of various bulk properties of the system such as transverse momentum ($p_T$) spectra, particle yields ($dN/dy$), mean transverse mass ($⟨m_T⟩$), and anti-particle to particle ratios. Model calculations using both default and string melting versions of the AMPT with three distinct sets of initial conditions are compared to the data from the STAR experiment. In the case of ${\pi }^{\pm }$, $K^{\pm }$, $p$, and $\overline{p}$, we observe that the string melting version shows better agreement with data at higher energies, while the default version performs better at lower collision energies. However, for $K_s^0$, $\Lambda$, and $\varphi$, it is observed that the default version is able to describe the data better at all energies. In addition, we have used the blast-wave model to extract the kinetic freeze-out properties, like the kinetic freeze-out temperature and the radial flow velocity. We observe that these parameters are comparable with the data.

    ↳ nucl-thhep-exhep-ph1 citation
23. 23*

    Supergeometric Quantum Effective Action

    Viola Gattus🇬🇧 · Apostolos Pilaftsis🇬🇧

    Supergeometric Quantum Field Theories (SG-QFTs) are theories that go beyond the standard supersymmetric framework, since they allow for general scalar-fermion field transformations on the configuration space of a supermanifold, without requiring an equality between bosonic and fermionic degrees of freedom. After revisiting previous considerations, we extend them by calculating the one-loop effective action of minimal SG-QFTs that feature non-zero fermionic curvature in two and four spacetime dimensions. By employing an intuitive approach to the Schwinger-DeWitt heat-kernel technique and a novel field-space generalised Clifford algebra, we derive the ultra-violet structure of characteristic effective-field-theory (EFT) operators up to four spacetime derivatives that emerge at the one-loop order and are of physical interest. Upon minimising the impact of potential ambiguities due to the so-called multiplicative anomalies, we find that the EFT interactions resulting from the one-loop supergeometric effective action are manifestly diffeomorphically invariant in configuration space. The extension of our approach to evaluating higher-loops of the supergeometric quantum effective action is described. The emerging landscape of theoretical and phenomenological directions for further research of SG-QFTs is discussed.

    ↳ hep-thhep-phPRD(2024)·12 citations
24. 24*

    Geometry of Classical Nambu-Goldstone Fields

    Slobodan Radošević🇷🇸

    A coordinate-free formulation of first order effective field theory, in which Nambu-Goldstone fields are described as sections on associated bundle, is presented. This construction, which is based only on symmetry considerations, allows for a direct derivation of number and types of Nambu-Goldstone fields in a classical field theory without any reference to effective Lagrangian. A central role in classification is shown to be played by Lorentz-symmetry breaking order parameter which induces symplectic structure in the field space of the theory.

    ↳ hep-thcond-mat.str-elhep-phAnnals Phys.(2025)·0 citations
25. 25*

    Beyond modified Urca: the nucleon width approximation for flavor-changing processes in dense matter

    Mark G. Alford🇺🇸 · Alexander Haber🇺🇸 · Ziyuan Zhang🇺🇸

    Flavor-changing charged current ("Urca") processes are of central importance in the astrophysics of neutron stars. Standard calculations approximate the Urca rate as the sum of two contributions, direct Urca and modified Urca. Attempts to make modified Urca calculations more accurate have been impeded by an unphysical divergence at the direct Urca threshold density. In this paper we describe a systematically improvable approach where, in the simplest approximation, instead of modified Urca we include an imaginary part of the nucleon mass (nucleon width). The total Urca rate is then obtained via a straightforward generalization of the direct Urca calculation, yielding results that agree with both direct and modified Urca at the densities where those approximations are valid. At low densities, we observe an enhancement of the rate by more than an order of magnitude, with important ramifications for neutron star cooling and other transport properties.

    ↳ nucl-thastro-ph.HEgr-qchep-phPRC(2024)·26 citations
26. 26*

    The Born regime of gravitational amplitudes

    Miguel Correia🇨🇦 · Giulia Isabella🇺🇸

    We study the $2\to 2$ scattering in the regime where the wavelength of the scattered objects is comparable to their distance but is much larger than any Compton wavelength in the quantum field theory. We observe that in this regime - which differs from the eikonal - the Feynman diagram expansion takes the form of a geometric series, akin to the Born series of quantum mechanics. Conversely, we can define the Feynman diagram expansion as the Born series of a relativistic effective-one-body (EOB) Schrödinger equation. For a gravitational theory in this regime we observe that the EOB Schrödinger equation reduces to the Regge-Wheeler or Teukolsky wave equations. We make use of this understanding to study the tree-level Compton scattering off a Kerr black hole. We compute the scalar and photon Compton amplitude up to $O(a^{30})$ in the black hole spin $a$ and propose an all-order expression. Remarkably, we find that boundary terms, which are typically neglected, give non-zero contact pieces necessary for restoring crossing symmetry and gauge invariance of the Kerr-Compton amplitude.

    ↳ hep-thgr-qchep-phJHEP(2025)·48 citations
27. 27*

    Abelian Instantons and Monopole Scattering

    Csaba Csáki🇺🇸 · Rotem Ovadia🇮🇱 · Ofri Telem🇮🇱 · John Terning🇺🇸 · Shimon Yankielowicz🇮🇱

    It is usually assumed that $4D$ instantons can only arise in non-Abelian theories. In this paper we re-examine this conventional wisdom by explicitly constructing instantons in an Abelian gauge theory: ${\mathrm{QED}}_4$ with $N_f$ flavors of Dirac fermions, in the background of a Dirac monopole. This is the low-energy effective field theory for fermions interacting with a 't Hooft-Polyakov monopole, in the limit where the monopole is infinitely heavy (hence pointlike) and static. This theory, whose non-topological sectors were studied by Rubakov and Callan, has a far richer structure than previously explored. We show how to calculate the topological instanton number, demonstrate the existence of 't Hooft zero modes localized around such instantons, and show how instantons in the path integral provide the underlying mechanism for the Callan-Rubakov process: monopole-catalyzed baryon decay with a cross section that saturates the unitarity bound. Our computation relies on correctly identifying the relevant $2D$ EFT for monopole catalysis as Axial ${\mathrm{QED}}_2$ in an effective $Ad{S}_2$ metric.

    ↳ hep-thhep-phJHEP(2024)·14 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.