Wed·Nov 6, 2024Wednesday·November 6, 2024

1. 01*

   Exploring the Interference between the Atmospheric and Solar Neutrino Oscillation Sub-Amplitudes

   Gabriela Barenboim🇪🇸 · Stephen J. Parke🇺🇸

   The interference between the atmospheric and solar neutrino oscillation sub-amplitudes is said to be responsible for CP violation (CPV) in neutrino appearance channels. More precisely, CPV is generated by the interference between the parts of the neutrino oscillation amplitude which are CP even and CP odd: even or odd when the neutrino mixing matrix is replaced with its complex conjugate. This is the CPV interference term, as it gives a contribution to the oscillation probability, the square of the amplitude, which is opposite in sign for neutrinos and anti-neutrinos and is unique. For this interference to be non-zero, at least two sub-amplitudes are required. There are, however, other interference terms, which are even under the above exchange, these are the CP conserving (CPC) interference terms. In this paper, we explore in detail these CPC interference terms and show that they cannot be uniquely defined, as one can move pieces of the amplitude from the atmospheric sub-amplitude to the solar sub-amplitude and vice versa. This freedom allows one to move the CPC interference terms around, but does not let you eliminate them completely. We also show that there is a reasonable definition of the atmospheric and solar sub-amplitudes for the appearance channels such that in neutrino disappearance probability there is no atmospheric-solar CPC interference term. However, with this choice, there is a CPC interference term within the atmospheric sector.

   hep-phhep-exPRD(2025)·0 citations
2. 02*

   Shedding Light on Evanescent Shadows -- Exploration of non-anticommuting ${\gamma }_5$ in Dimensional Regularisation

   Paul L. Ebert🇩🇪 · Paul Kühler🇩🇪 · Dominik Stöckinger🇩🇪 · Matthias Weißwange🇩🇪

   The mathematical consistency of the BMHV scheme of dimensional regularisation (DReg) comes at the cost of requiring symmetry-restoring counterterms to cancel the regularisation-induced breaking of gauge and BRST invariance. There is no unique way to extend a 4-dimensional theory to $D$ dimensions, and different choices can be made for the dimensionally regularised fermions, evanescent parts of their kinetic terms and evanescent gauge interactions. Here we present a detailed study of the impact of changing such evanescent details. We leverage this freedom to identify a particularly convenient formulation that simplifies practical calculations. In order to thoroughly study the available options, we focus on a general abelian chiral gauge theory including scalar fields and adopt a general approach to the BMHV implementation. This allows for specialisation to various models and different approaches, including those from the literature. Importantly, our model can be specialised to the abelian sector of the Standard Model (SM). Consequently, this article also serves as a roadmap for upcoming applications to the full SM.

   hep-phhep-thJHEP(2025)·11 citations
3. 03*

   The Fundamental Limit of Jet Tagging

   Joep Geuskens🇩🇪 · Nishank Gite🇺🇸 · Michael Krämer🇩🇪 · Vinicius Mikuni🇺🇸 · Alexander Mück🇩🇪 · Benjamin Nachman🇺🇸 · Humberto Reyes-González🇩🇪

   Identifying the origin of high-energy hadronic jets ('jet tagging') has been a critical benchmark problem for machine learning in particle physics. Jets are ubiquitous at colliders and are complex objects that serve as prototypical examples of collections of particles to be categorized. Over the last decade, machine learning-based classifiers have replaced classical observables as the state of the art in jet tagging. Increasingly complex machine learning models are leading to increasingly more effective tagger performance. Our goal is to address the question of convergence -- are we getting close to the fundamental limit on jet tagging or is there still potential for computational, statistical, and physical insights for further improvements? We address this question using state-of-the-art generative models to create a realistic, synthetic dataset with a known jet tagging optimum. Various state-of-the-art taggers are deployed on this dataset, showing that there is a significant gap between their performance and the optimum. Our dataset and software are made public to provide a benchmark task for future developments in jet tagging and other areas of particle physics.

   hep-phhep-exphysics.data-anPRD(2025)·11 citations
4. 04*

   Two lectures on Yang-Lee edge singularity and analytic structure of QCD equation of state

   Vladimir V. Skokov🇺🇸

   These lecture notes, prepared for the 2024 XQCD PhD, provide an introduction to the analytic structure of an equation of state near a second-order phase transition and its most prominent landmark: the Yang-Lee edge singularity. In addition to discussing general properties, the notes review recent theoretical progress in locating the QCD critical point by tracking the trajectory of the Yang-Lee edge singularity.

   hep-phhep-latSciPost Phys.Lect.Notes(2025)·10 citations
5. 05*

   Sketch of the resolution of the axial U(1) problem without chiral anomaly

   Nodoka Yamanaka🇯🇵

   We propose a mechanism which explains the masses of $\eta$ and ${\eta }^{\prime }$ mesons without invoking the explicit violation of $U(1{)}_A$ symmetry by the chiral anomaly. It is shown that the U(1) problem, the problem for which the prediction of $\eta$ and ${\eta }^{\prime }$ masses in the simple chiral perturbation theory largely deviates from the experimental values, is actually resolved by considering the first order contribution of the disconnected meson correlator with respect to the quark mass. The bound of Weinberg $m_{\eta }^2\le 3m_{\pi }^2$ is fulfilled by considering the negative squared mass of $\eta$ or ${\eta }^{\prime }$ which is just the saddle point of the QCD effective potential, and 20% level agreements with experimental data are obtained by just fitting one low energy constant. We provide the leading chiral Lagrangian due to the disconnected contribution in 3-flavor QCD, and also discuss the 2- and 4-flavor cases as well as the consistency of our mechanism with the chiral restoration at high temperature found in lattice calculations.

   hep-phhep-exhep-latnucl-th2 citations
6. 06*

   Electroweak Symmetry Breaking in Sp(6) Gauge-Higgs Unification Model

   Nobuhito Maru🇯🇵 · Akio Nago🇯🇵

   We study the electroweak symmetry breaking in a five dimensional $Sp(6)$ gauge-Higgs unification model where the weak mixing angle is predicted to be ${\sin }^2{\theta }_W=1/4$ at the compactification scale. We find that the correct pattern of electroweak symmetry breaking and a viable Higgs mass are realized by introducing a 4-rank totally symmetric representation and several adjoint fermions additionally.

   hep-phhep-thNPB(2025)·3 citations
7. 07*

   Study of $B\to \rho \eta$, $\rho {\eta }^{\prime }$ decays in the modified perturbative QCD approach

   Yun-Han Gui🇨🇳 · Mao-Zhi Yang🇨🇳

   We study the decay processes of $B\to \rho \eta$, $\rho {\eta }^{\prime }$ in the perturbative quantum chromodynamics (QCD) approach with a few improvements incorporated in it, where the contributions with large momentum transfer are calculated perturbatively, and the contributions with lower energy scale are treated by introducing soft transition form factors. In addition, color-octet contributions are introduced which are essentially long-distance contributions. With reasonable input parameters selected, we find that the theoretical results of the branching ratios and $CP$ violations are all consistent with experimental data. We also predict some unmeasured quantities, which can be tested by experiment in the future.

   hep-phPRD(2025)·3 citations
8. 08*

   Spectrum and decay properties of the charmed mesons involving the coupled channel effects

   Wei Hao🇨🇳 · M. Atif Sultan🇨🇳 · En Wang🇨🇳

   The mass spectrum of the charmed mesons is investigated by considering the coupled channel effects within the nonrelativistic potential model. The predicted masses of the charmed mesons are in agreement with experimental data. The strong decay properties are further analyzed within the ${}^3{P}_0$ model by using numerical wave functions obtained from nonrelativistic potential model. Based on the predicted masses and decay properties, we give a classification of the recently observed charmed states. Especially, we have effectively explained the masses and decay properties of the $D_1^{\ast }(2600)$ and $D_1^{\ast }(2760)$ by considering the $S$-$D$ mixing. Furthermore, the predicted masses and decay properties of the $2P$ wave states are helpful to search for them experimentally in future.

   hep-phPRD(2025)·8 citations
9. 09*

   Predicting New Above-Threshold Molecular States Via Triangular Singularities

   Yin Huang🇨🇳 · Xurong Chen🇨🇳

   Considering that the experimentally observed molecular states are significantly fewer than those predicted theoretically, and that these states are traditionally classified as lying below thresholds while several candidates are found above them, we propose to broaden the definition of molecular states to include those that exist just above the thresholds. Identifying resonance peaks in invariant mass distributions and scattering cross-sections is crucial for probing these states, yet the mechanisms responsible for such enhancements remain unclear, complicating our understanding of new particle production. While the peaks linked to triangular singularities do not correspond to true hadronic states, the associated production mechanisms may provide valuable insight into the search for genuine hadrons. In this work, we propose employing the triangular singularity mechanism to theoretically investigate yet-to-be-observed molecular states, particularly those that could test heavy quark symmetry. We argue that these states may have true masses surpassing the thresholds of their constituent components, rather than being predicted to be below them by theoretical models. Our findings suggest the possible existence of 18 predicted heavy quark molecular states, including $X(4014)$, $Z_{cs}(4123)$, $X_{c0}(4500)$, $X_{c1}(4685)$, $Y(4320)$, $Z(4430)$, and ${\rm Y}(11020)$, which are posited to contain $D^{\ast }{\bar{D}}^{\ast }$, $D^{\ast }{\bar{D}}_s^{\ast }$, \( D_{s1}^{+}D_{s}^{-} \),\( D_{s1}^{+}D_{s}^{*-} \), $D_1\bar{D}$, $D_1{\bar{D}}^{\ast }$, and $B_1(5721)\bar{B}$ constituents, respectively. The recognition of these states would substantiate heavy quark symmetry and enhance our understanding of hadronic dynamics and molecular states formation.

   hep-phhep-exhep-thPLB(2025)·3 citations
10. 10*

    Neutrino Electromagnetic Properties

    Carlo Giunti🇮🇹 · Konstantin Kouzakov🇷🇺 · Yu-Feng Li🇨🇳 · Alexander Studenikin🇷🇺

    Neutrinos are neutral in the Standard Model, but they have tiny charge radii generated by radiative corrections. In theories Beyond the Standard Model, neutrinos can also have magnetic and electric moments and small electric charges (millicharges). We review the general theory of neutrino electromagnetic form factors, which reduce, for ultrarelativistic neutrinos and small momentum transfers, to the neutrino charges, effective charge radii, and effective magnetic moments. We discuss the phenomenology of these electromagnetic neutrino properties and we review the existing experimental bounds. We briefly review also the electromagnetic processes of astrophysical neutrinos and the neutrino magnetic moment portal in the presence of sterile neutrinos.

    hep-phastro-ph.COhep-exAnn.Rev.Nucl.Part.Sci.(2025)·60 citations
11. 11*

    New physics effects in semileptonic $\overline{B_s}\to K^{\ast +}(\to K\pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ decay

    Shabana Khan🇮🇳 · Dinesh Kumar🇮🇳

    We analyze the new physics effects in semileptonic $\overline{B_s}\to K^{\ast +}(\to K\pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ decay induced by the $b\to u\ell {\nu }_{\ell }$ quark level transition. We consider the vector, scalar and tensor new physics Lorentz structures in addition to the SM in effective field theory approach. Constraints on new physics parameters are obtained from experimental observations of both semileptonic and leptonic decays of $B$ mesons, which are governed by the underlyng $b\to u\ell {\nu }_{\ell }$ transition. We explore the new physics effects in differential branching fraction, lepton forward-backward asymmetry, fraction of longitudinal polarization of $K^{\ast }$ meson and normalized angular observables in $\overline{B_s}\to K^{\ast +}(\to K\pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ decay.

    hep-phJ.Phys.G(2025)·1 citation
12. 12*

    Leptogenesis and neutrino mass with scalar leptoquarks

    Kåre Fridell🇯🇵

    Leptoquarks are known to generate a wide range of potentially observable phenomena, and have been searched for in different experiments. We show that the observed baryon asymmetry and neutrino mass scale can both be simultaneously produced in a model featuring scalar leptoquarks while avoiding existing experimental constraints and potentially leading to future observable signatures.

    hep-phJHEP(2025)·2 citations
13. 13*

    Kinetic structure of strong-field QED showers in crossed electromagnetic fields

    Mattys Pouyez🇫🇷 · Thomas Grismayer🇵🇹 · Mickael Grech🇫🇷 · Caterina Riconda🇫🇷

    A complete, kinetic description of electron-seeded strong-field QED showers in crossed electromagnetic fields is derived. The kinetic structure of the shower and its temporal evolution are shown to be a function of two parameters: the initial shower quantum parameter and radiation time. The latter determines the short and long time evolution of the shower. Explicit solutions for the shower multiplicity (number of pairs per seed electron) and the emitted photon spectrum are obtained for both timescales. Our approach is first derived considering showers in a constant, homogeneous magnetic field. We find that our results are valid for any crossed fields and we apply them to laboratory settings for which we obtain fully analytical, predictive scaling laws.

    hep-phhep-thphysics.plasm-phPRL(2025)·10 citations
14. 14*

    Inverse See-Saw Mechanism with ${\mathbf{S}}_3$ flavor symmetry

    Juan Carlos Gómez-Izquierdo🇲🇽 · Catalina Espinoza🇲🇽 · Lucia E. Gutiérrez Luna🇲🇽 · Myriam Mondragón🇲🇽

    The current neutrino experiments provide an opportunity for testing the inverse see-saw mechanism through charged lepton flavor violating processes and neutrinoless double beta decay. Motivated by this, in this paper we study the ${\mathbf{S}}_3\otimes {\mathbf{Z}}_2$ discrete symmetry in the $B-L$ gauge model where the active light neutrino mass matrix comes from the aforementioned mechanism. In this framework, the effect of complex vacuum expectation values of the Higgs doublets on the fermion masses is explored and, under certain assumptions on the Yukawa couplings, we find that the neutrino mixing is controlled by the Cobimaximal pattern, but a sizeable deviation from the charged lepton sector breaks the well known predictions on the atmospheric angle ($45^{\circ }$) and the Dirac CP-violating phase ($-90^{\circ }$). In addition, due to the presence of heavy neutrinos at the $TeV$ scale, charged lepton flavor violation (CLFV) and neutrinoless double beta decay get notable contributions. Analytical formulae for these observables are obtained, and then a numerical calculation allows to fit quite well the lepton mixing for the normal and inverted hierarchies, however, the branching ratios decay values for CLFV disfavors the latter one. Along with this, the region of parameter space for the $m_{ee}$ effective neutrino mass lies below the GERDA bounds for both the normal and inverted hierarchies. On the other hand, with a particular benchmark, the quark mass matrices are found to have textures that allow to fit with great accuracy the CKM mixing matrix.

    hep-phNPB(2025)·6 citations
15. 15*

    Daily modulation of low-energy nuclear recoils from sub-GeV dark matter

    Connor Stratman🇺🇸 · Tongyan Lin🇺🇸

    At sufficiently low nuclear recoil energy, the scattering of dark matter (DM) in crystals gives rise to single phonon and multiphonon excitations. In anisotropic crystals, the scattering rate into phonons modulates over each sidereal day as the crystal rotates with respect to the DM wind. This gives a potential avenue for directional detection of DM. The daily modulation for single phonons has previously been calculated. Here we calculate the daily modulation for multiphonon excitations from DM in the mass range 1 MeV-1 GeV. We generalize previous multiphonon calculations, which made an isotropic approximation, and implement results in the DarkELF package. We find daily modulation rates up to 1-10 percent for an Al${}_2$O${}_3$ target and DM mass below 30 MeV, depending on the recoil energies probed. We obtain similar results for SiC, while modulation in Si, GaAs and SiO${}_2$ is negligible.

    hep-phhep-exPRD(2025)·9 citations
16. 16*

    A Cosmological Solution to the Doublet-Triplet Splitting Problem

    Csaba Csaki🇺🇸 · Raffaele Tito D'Agnolo🇫🇷 · Eric Kuflik🇮🇱 · Pablo Sesma🇫🇷

    We propose a model that provides a simultaneous solution to the doublet-triplet splitting problem of grand unified theories, the electroweak hierarchy problem and the strong CP problem. The mechanism is based on the dynamics of two axion-like particles that would crunch the universe at the time of the QCD phase transition if triplets were light or had a VEV or if doublets were heavy or did not have a VEV. The only trace left at low energies are these two axion-like particles. They are weakly coupled to the Standard Model and could be detected at upcoming axion experiments or by a combination of neutron EDM measurements and the astrophysical detection of fuzzy dark matter.

    hep-phhep-thJHEP(2025)·6 citations
17. 17*

    Hunting New Animalcula with Rare K and B Decays

    Andrzej J. Buras🇩🇪

    We summarize the recent strategy for an efficient hunting of new animalcula with the help of rare K and B decays that avoids the use of the $V_{cb}$ and $V_{ub}$ parameters that are subject to tensions between their determinations from inclusive and exclusive decays. In particular we update the values of the $V_{cb}$-independent ratios of various K and B decay branching ratios predicted by the Standard Model. We also stress the usefulness of the $V_{cb}-\gamma$ plots in the search for new physics. We select the magnificant seven among rare K and B decays that should play a leading role in the search for new physics due to their theoretical cleanness: $B^{+}\to K^{+}(K^{\ast })\nu \bar{\nu }$ and $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ measured recently by Belle II and NA62, respectively, $K_L\to {\pi }^0\nu \bar{\nu }$ investigated by KOTO and also $B_{s,d}\to {\mu }^{+}{\mu }^{-}$ and $K_S\to {\mu }^{+}{\mu }^{-}$ measured by the LHCb, CMS and ATLAS experiments at CERN. %

    hep-phhep-exhep-latEPJ Web Conf.(2024)·3 citations
18. 18*

    Spherically symmetric Earth models yield no net electron spin

    Nathan B. Clayburn🇺🇸 · Andrew Glassford🇺🇸 · Andrew Leiker🇺🇸 · Thomas Uelmen🇺🇸 · Jung-Fu Lin🇺🇸 · Larry R. Hunter🇺🇸

    Terrestrial experiments that use electrons in Earth as a spin-polarized source have been demonstrated to provide strong bounds on exotic long-range spin-spin and spin-velocity interactions. These bounds constrain the coupling strength of many proposed ultralight bosonic dark-matter candidates. Recently, it was pointed out that a monopole-dipole coupling between the Sun and the spin-polarized electrons of Earth would result in a modification of the precession of the perihelion of Earth. Using an estimate for the net spin-polarization of Earth and experimental bounds on Earth's perihelion precession, interesting constraints were placed on the magnitude of this monopole-dipole coupling. Here we investigate the spin associated with Earth's electrons. We find that there are about $6\times 10^{41}$ spin-polarized electrons in the mantle and crust of Earth oriented anti-parallel to their local magnetic field. However, when integrated over any spherically-symmetric Earth model, we find that the vector sum of these spins is zero. In order to establish a lower bound on the magnitude of the net spin along Earth's rotation axis we have investigated three of the largest breakdowns of Earth's spherical symmetry: the large low shear-velocity provinces of the mantle, the crustal composition, and the oblate spheroid of Earth. From these investigations we conclude that there are at least $5\times 10^{38}$ spin-polarized electrons aligned anti-parallel to Earth's rotation axis. This analysis suggests that the bounds on the monopole-dipole coupling that were extracted from Earth's perihelion precession need to be relaxed by a factor of about 2000.

    hep-phastro-ph.EPphysics.geo-phPRD(2025)·3 citations
19. 19*

    Constraining ultralight scalar dark matter couplings with the European Pulsar Timing Array second data release

    Yu-Mei Wu🇨🇳 · Qing-Guo Huang🇨🇳

    Pulsar Timing Arrays (PTAs) offer an independent method for searching for ultralight dark matter (ULDM), whose wavelike nature induces periodic oscillations in the arrival times of radio pulses. In addition to this gravitational effect, the direct coupling between ULDM and ordinary matter results in pulsar spin fluctuations and reference clock shifts, leading to observable effects in PTAs. The second data release from the European PTA (EPTA) indicates that ULDM cannot account for all dark matter in the mass range $m_{\varphi }\in [10^{-24.0},10^{-23.3}]\text{ eV}$ based solely on gravitational effects. In this work, we derive constraints on the coupling coefficients by considering both gravitational and coupling effects. Our results demonstrate that EPTA provides stronger constraints on these couplings than previous PTA experiments, and it establishes similar or even tighter constraints compared to other precise experiments, such as atomic clock experiments.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2025)·5 citations
20. 20*

    Gauge theory for topological waves in continuum fluids with odd viscosity

    Keisuke Fujii🇯🇵 · Yuto Ashida🇯🇵

    We consider two-dimensional continuum fluids with odd viscosity under a chiral body force. The chiral body force makes the low-energy excitation spectrum of the fluids gapped, and the odd viscosity allows us to introduce the first Chern number of each energy band in the fluids. Employing a mapping between hydrodynamic variables and U(1) gauge-field strengths, we derive a U(1) gauge theory for topologically nontrivial waves. The resulting U(1) gauge theory is given by the Maxwell-Chern-Simons theory with an additional term associated with odd viscosity. We then solve the equations of motion for the gauge fields concretely in the presence of the boundary and find edge-mode solutions. We finally discuss the fate of bulk-boundary correspondence (BBC) in the context of continuum systems.

    ↳ cond-mat.softcond-mat.str-elhep-phhep-th+1SciPost Phys.Core(2025)·1 citation
21. 21*

    Multivariate hypergeometric solutions of cosmological (dS) correlators by $\text{d}\log$-form differential equations

    Jiaqi Chen🇨🇳 · Bo Feng🇨🇳 · Yi-Xiao Tao🇨🇳

    In this paper, we give the analytic expression for the homogeneous part of solutions of arbitrary tree-level cosmological correlators, including massive propagators and time-derivative interaction cases. The solutions are given in the form of multivariate hypergeometric functions. It is achieved by two steps. Firstly, we indicate the factorization of the homogeneous part of solutions, i.e., the homogeneous part of solutions of multiple vertices is the product of the solutions of the single vertex. Secondly, we give the solution to the $\text{d}\log$-form differential equations of arbitrary single vertex integral family. We also show how to determine the boundary conditions for the differential equations. There are two techniques we developed for the computation. Firstly, we analytically solve $\text{d}\log$-form differential equations via power series expansion. Secondly, we handle degenerate multivariate poles in power series expansion of differential equations by blow-up. They could also be useful in the evaluation of multi-loop Feynman integrals in flat spacetime.

    ↳ hep-thgr-qchep-phJHEP(2025)·25 citations
22. 22*

    Combining strongly lensed and unlensed fast radio bursts: To be a more precise late-universe probe

    Ji-Guo Zhang🇺🇸 · Yi-Fan Jiang🇨🇳 · Ze-Wei Zhao🇺🇸 · Jing-Zhao Qi🇺🇸 · Jing-Fei Zhang🇺🇸 · Xin Zhang🇺🇸

    The Macquart relation and time-delay cosmography are now two promising ways to fast radio burst (FRB) cosmology. In this work, we propose a joint method that combines strongly lensed and unlensed FRBs for improving cosmological parameter estimation by using simulated FRB data from the future sensitive coherent all-sky monitor survey, which is expected to detect a large number of FRBs including galaxy-galaxy strongly lensed events. We find that using a detectable sample of 100,000 localized FRBs including $40$ lensed events can simultaneously constrain the Hubble constant and the equation of state of dark energy, with high precision of $\epsilon (H_0)=0.4\%$ and $\epsilon (w)=4.5\%$ in the simplest dynamical dark energy model. The joint analysis of unlensed and lensed FRBs significantly improves the constraint on $H_0$, which could be more effective than combining either the unlensed FRBs with future gravitational wave (GW) standard sirens or the lensed FRBs with CMB. Furthermore, combining the full FRB sample with the CMB+BAO+SNe data yields $\sigma (H_0)=0.29\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$, $\sigma (w_0)=0.046$, and $\sigma (w_a)=0.15$ in the two-parameter dynamical dark energy model, which outperform the results from the CMB+BAO+SNe+GW data. This reinforces the cosmological implications of a multi-wavelength observational strategy in optical and radio bands. We conclude that the future FRB observations will shed light on the nature of dark energy and also the Hubble tension if enough events with long-duration lensing are incorporated.

    ↳ astro-ph.COgr-qchep-phSCPMA(2025)·21 citations
23. 23*

    Lattice QCD calculation of the subtraction function in forward Compton amplitude

    Yang Fu🇺🇸 · Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸 · Chuan Liu🇨🇳 · Shi-Da Wen🇨🇳

    The subtraction function plays a pivotal role in calculations involving the forward Compton amplitude, which is crucial for predicting the Lamb shift in muonic atom, as well as the proton-neutron mass difference. In this work, we present a lattice QCD calculation of the subtraction function using two domain wall fermion gauge ensembles at the physical pion mass. We utilize a recently proposed subtraction point, demonstrating its advantage in mitigating statistical and systematic uncertainties by eliminating the need for ground-state subtraction. Our results reveal significant contributions from $N\pi$ intermediate states to the subtraction function. Incorporating these contributions, we compute the proton, neutron and nucleon isovector subtraction functions at photon momentum transfer $Q^2\in [0,2]$ GeV${}^2$. For the proton subtraction function, we compare our lattice results with chiral perturbation theory prediction at low $Q^2$ and with the results from the perturbative operator-product expansion at high $Q^2$. Finally, using these subtraction functions as input, we determine their contribution to two-photon exchange effects in the Lamb shift and isovector nucleon electromagnetic self-energy.

    ↳ hep-lathep-phnucl-thPRL(2025)·4 citations
24. 24*

    Revisiting constraints on primordial magnetic fields from spectral distortions of cosmic microwave background

    Fumio Uchida🇯🇵 · Kohei Kamada🇨🇳 · Hiroyuki Tashiro🇯🇵

    The magneto-hydrodynamic decay of primordial magnetic fields can distort the black-body spectrum of the cosmic microwave background (CMB) by draining magnetic energy into thermal plasmas and photons. The current limits on CMB distortion place constraints on small-scale primordial magnetic fields. The constraints crucially depend on the decay laws of primordial magnetic fields. Recent numerical simulations reveal that non-linear effects play a significant role in the magnetic field decay although these effects are neglected in previous works. In this paper, by adopting a reconnection-driven turbulent decay as a non-linear evolution model, we demonstrate the potential impact of non-linear effects on CMB spectral distortions. The reconnection-driven turbulent decay model is an analytical description which provides the consistent results with numerical simulation. Our results rule out magnetic fields with shorter coherence lengths. While the result is independent of the spectral index of the magnetic energy spectrum, it is influenced by the magnetic helicity fraction.

    ↳ astro-ph.COhep-phPLB(2025)·8 citations
25. 25*

    The tidal evolution of anisotropic subhaloes: A new pathway to creating isotropic and cored satellites

    Barry T. Chiang🇺🇸 · Frank C. van den Bosch🇺🇸 · Hsi-Yu Schive🇹🇼

    It is common practice, both in dynamical modelling and in idealised numerical simulations, to assume that galaxies and/or dark matter haloes are spherical and have isotropic velocity distributions, such that their distribution functions are ergodic. However, there is no good reason to assume that this assumption is accurate. In this paper we use idealised $N$-body simulations to study the tidal evolution of subhaloes that are anisotropic at infall. We show that the detailed velocity anisotropy has a large impact on the subhalo's mass loss rate. In particular, subhaloes that are radially anisotropic experience much more mass loss than their tangentially anisotropic counterparts. In fact, in the former case, the stripping of highly radial orbits can cause a rapid cusp-to-core transformation, without having to resort to any baryonic feedback processes. Once the tidal radius becomes comparable to the radius of the core thus formed, the subhalo is tidally disrupted. Subhaloes that at infall are tangentially anisotropic are far more resilient to tidal stripping, and are never disrupted when simulated with sufficient resolution. We show that the preferential stripping of more radial orbits, combined with re-virialisation post stripping, causes an isotropisation of the subhalo's velocity distributions. This implies that subhaloes that have experienced significant mass loss are expected to be close to isotropic, which may alleviate the mass-anisotropy degeneracies that hamper the dynamical modelling of Milky Way satellites.

    ↳ astro-ph.GAastro-ph.COhep-phMNRAS(2025)·9 citations
26. 26*

    A Bayesian Model of Credence in Low Energy Supersymmetry

    Richard Dawid🇸🇪 · James D. Wells🇺🇸

    We carry out a quantitative Bayesian analysis of the evolution of credences in low energy supersymmetry (SUSY) in light of the most relevant empirical data. The analysis is based on the assumption that observers apply principles of optimism or pessimism about theory building in a coherent way. On this basis, we provide a rough assessment of the current range of plausible credences in low energy SUSY and determine in which way LHC data changes those credences. For observers who had been optimistic about low energy SUSY before the LHC, the method reports that LHC data does lead to decreased credences in accordance with intuition. The decrease is moderate, however, and keeps posteriors at very substantial levels. The analysis further establishes that a very high but not yet indefensible degree of pessimism regarding the success chances of theory building still results in quite significant credences in GUT and low energy SUSY for the time right before the start of the LHC. The pessimist's credence in low energy SUSY remains nearly unchanged once LHC data is taken into account.

    ↳ physics.hist-phhep-phSynthese(2025)·1 citation

* 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.