Wed·Oct 16, 2024Wednesday·October 16, 2024

1. 01*

   Quasielastic Lepton-Nucleus Scattering and the Correlated Fermi Gas Model

   Gil Paz🇺🇸

   The future neutrino research program will require improved precision. A major source of uncertainty is the interaction of neutrinos with nuclei that serve as targets for such experiments. Broadly speaking, this interaction often depends, e.g., for Charge-Current Quasi-Elastic (CCQE) scattering, on the combination of "nucleon physics" expressed by form factors and "nuclear physics" expressed by a nuclear model. It is important to get a good handle on both. This talk presents a fully analytic implementation of the Correlated Fermi Gas (CFG) Model for CCQE electron-nuclei and neutrino-nuclei scattering. The implementation is used to compare separately form factors and nuclear model effects for both electron-carbon and neutrino-carbon scattering data.

   hep-phhep-exhep-latnucl-ex+1PoS(2025)·0 citations
2. 02*

   Higher precision constraints on the tau $g-2$ in LHC photon-initiated production: a full account of hadron dissociation and soft survival effects

   L. A. Harland-Lang🇬🇧

   We present the first calculation of photon-initiated $\tau$ pair production in the presence of non-zero anomalous magnetic ($a_{\tau }$) and/or electric dipole ($d_{\tau }$) moments of the $\tau$ lepton that accounts for the non-trivial interplay between these modifications with the soft survival factor and the possibility of dissociation of the hadron (proton or ion) beam. The impact of these is on general grounds not expected to have a uniform dependence on the value of $a_{\tau },d_{\tau }$, but in all previous analyses this assumption has been made. We have therefore investigated the importance of these effects in the context of photon-initiated $\tau$ pair production in both pp and PbPb collisions. This is in general found to be relatively small, at the percent level in terms of any extracted limits or observations of $a_{\tau },d_{\tau }$, such that these effects can indeed be safely ignored in existing experimental analyses. However, as the precision of such determinations increases in the future, the relevance of these effects will likewise increase. With this in mind we have made our calculation publicly available in the SuperChic Monte Carlo generator, including the possibility to simulate this process for varying $a_{\tau },d_{\tau }$ without rerunning.

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

   Constraining New Physics with $h\to VV$ Tomography

   Matthew Sullivan🇺🇸

   The application of quantum information methods to high energy physics has recently been gaining traction. In particular, reconstructing density matrices and measuring entanglement have been investigated for top quark decays and Higgs decays. This paper will further investigate the utility of density matrices for Higgs decays to vector bosons. Imprints of new physics, whether CP-even or CP-odd, in $h\to VV$ will generally change the spin density matrix, and so the tomographic reconstruction of the density matrix can constrain, or potentially detect, such new physics. New physics, expressed in the language of the Standard Model effective field theory, is analyzed in this framework of quantum tomography. Prospects for $h\to WW$ are good due to the fully chiral coupling of the $W$ boson to fermions, while $h\to ZZ$ requires around an order of magnitude more events to reach comparable sensitivity.

   hep-ph22 citations
4. 04*

   The inflation trilogy and primordial black holes

   Paulo B. Ferraz🇵🇹 · João G. Rosa🇵🇹

   We propose an inflation scenario with three independent stages of cold, warm and thermal inflation, respectively, driven by different scalar fields, motivated by the large number of such fields predicted in most extensions of the Standard Model. We show, in particular, that the intermediate period of warm inflation naturally leads to large density fluctuations on small scales, which can lead to primordial black hole formation in the mass window where they may account for all dark matter. This type of scenario yields a distinctive primordial black hole mass function with a mass gap, with the final period of thermal inflation diluting the abundance of very light black holes.

   hep-phastro-ph.COgr-qcJCAP(2025)·5 citations
5. 05*

   Top Quark Electroweak Dipole Moment at a High Energy Muon Collider

   Tao Han🇺🇸 · Da Liu🇺🇸 · Si Wang🇺🇸

   We study the sensitivity reach to probe the electroweak dipole operators associated with a top quark at a multi-TeV lepton collider. Studying the electroweak dipole operators is strongly motivated by precision physics. The operators exhibit unique chiral structure and can be enhanced with respect to others in theories beyond the Standard Model. We illustrate this point in a strongly coupled composite Higgs model. We find that a high energy ${\mu }^{+}{\mu }^{-}$ collider may offer unique opportunity to probe the electroweak dipole operators beyond the coverage by the LHC and future hadron colliders. The significant sensitivity is achieved by the leading channel ${\mu }^{+}{\mu }^{-}\to t\bar{t}$ near the threshold, and substantially improved by the novel channel ${\mu }^{+}{\mu }^{-}\to t\bar{t}h$ at high energies. We may be able to reach a new physics scale well above the collider energy for moderate couplings of the Wilson coefficients. Our main conclusions are applicable to future $e^{+}{e}^{-}$ colliders.

   hep-phhep-exPRD(2025)·11 citations
6. 06*

   Symmetries from outer automorphisms and unorthodox group extensions

   Christian Döring🇧🇪 · Andreas Trautner🇩🇪

   Symmetries play an essential role in the construction and phenomenology of quantum field theories (QFTs). We discuss how to construct symmetries of QFTs by extending minimal "seed" symmetry groups to larger groups that contain the seed(s) as subgroup(s). On the one hand, there are so-called "normal" extensions, which are given by outer automorphisms of the original symmetry group (including the trivial one) and contain the seed as a normal subgroup. On the other hand, there can be "unorthodox extensions" which do not have this property. We demonstrate our logic on the most general scalar potentials of the two- and three-Higgs-doublet models (2HDM and 3HDM). For the 2HDM, we show that all symmetry groups, including the different possible classes of CP and continuous symmetry groups, can be obtained from extensions of the smallest possible symmetry CP1 by consecutive outer automorphisms. Scanning over normal and unorthodox group extensions might be the easiest way to "machine learn" the possible symmetries of a QFT. However, many of the groups constructible in this way may not be realizable in a concrete model, in the sense that they lead to additional accidental symmetries. Hence, we also comment on a different, "top-down" way to obtain the possible realizable symmetry groups of a QFT based on the covariant transformation of couplings under the most general basis changes.

   hep-phhep-thquant-phJ.Phys.A·10 citations
7. 07*

   Phenomenology of the semileptonic ${\Sigma }_b^{\ast 0}\to {\Sigma }_c^{+}\ell {\bar{\nu }}_{\ell }$ transition within QCD sum rules

   L. Khajouei🇮🇷 · K. Azizi🇮🇷

   We conduct an investigation on the spin $\frac{3}{2}\to \frac{1}{2}$ semileptonic weak transition of single heavy baryons for the exclusive decay ${\Sigma }_b^{\ast 0}\to {\Sigma }_c^{+}\ell {\bar{\nu }}_{\ell }$ in three possible lepton channels within the three point QCD sum rule method. We compute the responsible form factors of this semileptonic decay by incorporating both perturbative and nonperturbative contributions of the operator product expansion series up to a mass dimension six. Having acquired the form factors, the decay widths of the processes in all lepton channels are determined. Our findings as well as possible future experimental information can be employed in order to check the SM predictions and explore the possibility of new physics in heavy baryonic decay channels.

   hep-phhep-exhep-latPRD(2025)·5 citations
8. 08*

   Unified Interpretation of 95 GeV Excesses in the Two Higgs Doublet type II Seesaw Model

   Brahim Ait-Ouazghour🇲🇦 · Mohamed Chabab🇲🇦 · Khalid Goure🇲🇦

   In the search for a light Higgs boson, the ATLAS and CMS experiments have observed excesses in both the diphoton ($\gamma \gamma$) and di-tau-pair (${\tau }^{+}{\tau }^{-}$) decay channels at about $95$ GeV. The LEP collaboration has also previously reported an excess in the $b\bar{b}$ channel at a comparable Higgs mass. In this paper, we explore whether these excesses can be accommodated within the framework of the Two Higgs Doublet type II Seesaw Model (2HDMcT). By implementing various theoretical constraints and experimental limits on the parameter space, we first demonstrate that a light CP-even Higgs boson, $h_1$, with a mass around 95 GeV can simultaneously account for the excesses observed in the $\gamma \gamma$ and $b\bar{b}$ channels, provided a Type I Yukawa texture is employed. More interestingly, our analysis shows that the three excesses in $\gamma \gamma$, $b\bar{b}$ and ${\tau }^{+}{\tau }^{-}$ channels can well be accommodated simultaneously, reaching a $0.64\sigma$ C.L. if the CP-odd Higgs boson $A_1$ is nearly mass degenerate and superposed to the light CP-even Higgs $h_1$.

   hep-phhep-exEur.Phys.J.Plus(2026)·12 citations
9. 09*

   Universal Mass Equation for Equal-Quantum Excited-States Sets I

   L. David Roper (VPI)🇺🇸 · Igor Strakovsky (GWU)🇺🇸

   The masses of fifteen baryon sets and twenty-four meson sets of three or more equal-quantum excited states, using Breit-Wigner PDG masses and their uncertainties at fixed $J^P$ for baryons and $J^{PC}$ for mesons, are fitted by a simple two-parameter logarithmic function, $M_n=\alpha Ln(n)+\beta$, where $n$ is the level of radial excitation. The conjecture is made that accurately measured masses of all equal-quantum baryons (including LHCb exotic $P_{c\bar{c}}^{+}$s) and meson excited states (including $s\bar{s}$, $s\bar{c}$, $c\bar{c}$, $c\bar{b}$, and $b\bar{b}$ states) are related by the logarithmic function used here; at least for the mass range of currently known excited states. The baryon ``star'' rating case is evaluated. The Cornell potential is an example of how a logarithmic behavior can be explained by an appropriate potential. Thus, a ``universal mass equation'' (UME) for equal-quantum excited-state sets is presented.

   hep-phhep-exnucl-exnucl-thEPJA(2025)·10 citations
10. 10*

    Experimental Road to a Charming Family of Tetraquarks ... and Beyond

    Feng Zhu🇨🇳 · Gerry Bauer🇨🇳 · Kai Yi🇨🇳

    Discovery of the X(3872) meson in 2003 ignited intense interest in exotic (neither $q\bar{q}$ nor $qqq$) hadrons, but a $c\bar{c}$ interpretation of this state was difficult to exclude. An unequivocal exotic was discovered in the $Z_c(3900{)}^{+}$ meson -- a charged charmonium-like state. A variety of models of exotic structure have been advanced but consensus is elusive. The grand lesson from heavy quarkonia was that heavy quarks bring clarity. Thus, the recently reported triplet of all-charm tetraquark candidates -- $X(6600)$, $X(6900)$, and $X(7100)$ -- decaying to $J/\psi J/\psi$ is a great boon, promising important insights. We review some history of exotics, chronicle the road to prospective all-charm tetraquarks, discuss in some detail the divergent modeling of $J/\psi J/\psi$ structures, and offer some inferences about them. These states form a Regge trajectory and appear to be a family of radial excitations. A reported, but unexplained, threshold excess could hint at a fourth family member. We close with a brief look at a step beyond: all-bottom tetraquarks.

    hep-phhep-exChin.Phys.Lett.(2024)·29 citations
11. 11*

    Implications of electromagnetic scale anomaly to QCD chiral phase transition in smaller quark mass regime: $T_{\mathrm{pc}}$ does not drop with eB

    Yuanyuan Wang🇨🇳 · Mamiya Kawaguchi🇨🇳 · Shinya Matsuzaki🇨🇳 · Akio Tomiya🇯🇵

    The decrease of the chiral pseudocritical temperature $T_{\mathrm{pc}}$ with an applied strong magnetic field has been extensively investigated by various QCD low-energy effective models and lattice QCD at physical point. We find that this decreasing feature may not hold in the case with a weak magnetic field and still depends on quark masses: when the quark masses get smaller, $T_{\mathrm{pc}}$ turns to increase with the weak magnetic field. This happens due to the significant electromagnetic-scale anomaly contribution in the thermomagnetic medium. We demonstrate this salient feature by employing the Nambu-Jona-Lasinio model with 2 + 1 quark flavors including the electromagnetic-scale anomaly contribution. We observe that at $(m_{0c},m_{sc})\simeq (2,20)\mathrm{MeV}$ for the isospin symmetric mass for up and down quarks, $m_0$, and the strange quark mass, $m_s$, $T_{\mathrm{pc}}$ decreases with the magnetic field if the quark masses exceed the critical values, and increases as the quark masses become smaller. Related cosmological implications, arising when the supercooled electroweak phase transition or dark QCD cosmological phase transition is considered along with a primordial magnetic field, are also briefly addressed.

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

    Non-diagonal DVCS and transition GPDs: A unified framework for spinless hadron case ${\gamma }^{\ast }\pi \to \gamma \pi \pi$

    Sangyeong Son🇰🇷 · Kirill M. Semenov-Tian-Shansky🇰🇷

    Hadron-to-two-hadron transition generalized parton distributions (GPDs) extend the concept of hadron-to-resonance transition GPDs and provide a unified description of non-diagonal hard exclusive reactions in the generalized Bjorken limit. We present the formalism for the case of spinless hadrons addressing the non-diagonal deeply virtual Compton scattering ${\gamma }^{\ast }\pi \to \gamma \pi \pi$ in terms of $\pi \to \pi \pi$ transition GPDs, which generalize GPDs for $\pi \to f_0,\rho ,f_2,\cdots$ transitions. We work out the basic properties of $\pi \to \pi \pi$ transition GPDs and establish the soft pion theorems at the $2\pi$ production threshold. We construct the partial wave expansion of $\pi \to \pi \pi$ transition GPDs in the two-pion decay angles and employ the dispersive approach to constrain $\pi \to \pi \pi$ transition GPDs in terms of $\pi \pi$-scattering phases with help of the Omnès representation. We estimate the $e^{-}{\pi }^{+}\to e^{-}\gamma {\pi }^{+}{\pi }^0$ cross section in the kinematics of the JLab@12 GeV incorporating the isolated $\rho (770)$ resonance state and work out the angular distributions of the cross section, specifying the observables sensitive to the polarization states of the produced $\rho (770)$ resonance.

    hep-phnucl-thJHEP(2025)·4 citations
13. 13*

    Non-perturbative suppression of Chiral Effects in hot QGP for $\Lambda /\bar{\Lambda }$-hyperons spin polarization in heavy-ion collisions

    Ruslan A. Abramchuk🇮🇱

    We review the calculation of suppression of Chiral Separational and Chiral Vortical Effects for strange quarks (which allegedly yield spin polarization of $\Lambda /\bar{\Lambda }$-hyperons in peripheral Heavy-Ion Collisions) by the non-perturbative interactions in hot deconfined QCD with the Field Correlator Method. The parameter range in the temperature-baryon density plane is expected to cover LHC-ALICE and RHIC-STAR data.

    hep-phhep-lathep-thIJMPE(2024)·1 citation
14. 14*

    Monte Carlo results on the Collins asymmetries in $e^{+}{e}^{-}$ annihilation

    A. Kerbizi🇮🇹 · L. Lönnblad🇸🇪 · A. Martin🇮🇹

    The quark spin effects have been introduced in the Pythia 8 Monte Carlo event generator for the simulation of $e^{+}{e}^{-}$ annihilation by interfacing the generator with the StringSpinner package. The package allows to simulate quark spin effects in the string fragmentation routine of Pythia by using the string+${}^3{P}_0$ model, recently applied to the fragmentation of a string stretched between a quark-antiquark pair with correlated spin states. StringSpinner is used to carry out simulations of $e^{+}{e}^{-}$ annihilation at the center of mass energy of $10.6\mathrm{GeV}$. The Collins asymmetries are extracted from the simulated data for back-to-back pion pairs using both the thrust axis method and the hadronic plane method. The results are compared with the data from the BELLE and BABAR experiments, finding a satisfactory agreement.

    hep-phPoS(2024)·0 citations
15. 15*

    Constraints on neutrino-Majoron couplings using SN1987A data

    Pilar Iváñez-Ballesteros (APC, Paris)🇫🇷 · M. Cristina Volpe (APC, Paris)🇫🇷

    Neutrino decay to a lighter neutrino and a massless or almost massless (pseudo)scalar Goldstone boson remains of wide interest, as in the search for ultralight dark matter or for neutrinoless double beta-decay, and for its implications in astrophysics and cosmology. Neutrino interactions with Majorons can affect the dynamics of supernovae and impact the emitted neutrino flux. Using a three-neutrino framework and detailed supernova simulations, we perform the first likelihood analysis of the 24 neutrino events from SN1987A, including nonradiative decay in matter to a massless (pseudo)scalar boson like a Majoron. Focusing on the induced spectral distortions, we present bounds on the neutrino-Majoron couplings, as a function of the lightest neutrino mass, that are either complementary or competitive with current ones.

    hep-phastro-ph.HEastro-ph.SRhep-ex+2PRD(2025)·9 citations
16. 16*

    Renormalization group running effects in $pp\to t\bar{t}h$ in the SMEFT

    Stefano Di Noi🇮🇹

    We analyze the effects of renormalization group running of the Wilson coefficients in the SMEFT in the context of single Higgs production in association with a top-antitop pair. In particular, we analyze the differential cross section with respect to the Higgs trasnverse momentum. We extend the usual $O({\alpha }_s)$ analysis including also the top Yukawa running effects, whose impact can be significant when large Wilson coefficients are considered. We employ a dynamical and a fixed renormalization scale with different set-ups for the Wilson coefficients, defined at the TeV scale. Additionally, we comment on the accuracy of the widely-used first leading-logarithm approximation.

    hep-phPoS(2025)·0 citations
17. 17*

    Frequency shifts induced by light scalar fields

    Christian Käding🇦🇹

    Light scalar fields are frequently used in modern physics, for example, as candidates for dark energy or dark matter. Open quantum dynamical effects, like frequency shifts, induced by such fields in probe particles used in interferometry experiments might open up new perspectives for constraining such models. In this article, we consider a probe scalar particle as a rough approximation for an atom in matter wave interferometry and discuss the frequency shifts induced by interactions with an environment comprising either one of two screened scalar field models: chameleons or symmetrons. For the $n=-4$ chameleon, we revise a previously obtained expression for the induced frequency shift, but confirm that it can likely not be used to obtain new constraints. However, for symmetrons, we find that induced frequency shifts have the potential to tightly constrain previously unreachable parts of the parameter space.

    hep-phastro-ph.COgr-qchep-th+1Phys.Dark Univ.(2025)·13 citations
18. 18*

    Double parton distributions of the proton from basis light-front quantization

    Tian-Cai Peng🇨🇳 · Zhi Hu🇯🇵 · Sreeraj Nair🇨🇳 · Siqi Xu🇨🇳 · Xiang Liu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

    Within the basis light-front quantization framework, we systematically investigate the unpolarized and longitudinally polarized double parton distributions (DPDs) of quarks inside the proton. We utilize the light-front wave functions of the proton derived in the valence sector from a Hamiltonian quantized on the light-front. The interaction terms of the Hamiltonian consist of a one-gluon exchange interaction at fixed coupling and a three-dimensional confinement potential. Our current analysis yields significant correlations of the quarks' longitudinal momenta with their transverse separation. We also demonstrate that our calculations do not support the commonly used $x-{\vec{k}}_{\perp }$ factorization of the DPDs in $x$ and $k_{\perp }$. Our results are qualitatively consistent with those of other phenomenological models.

    hep-phPRD(2025)·6 citations
19. 19*

    Hadron-quark hybrid model, modular transformation and Roberge-Weiss transition

    Hiroaki Kouno🇯🇵 · Riki Oshima🇯🇵 · Motoi Tachibana🇯🇵 · Kouji Kashiwa🇯🇵

    In the framework of modular transformations, we reformulate the recently proposed hadron-quark hybrid model when the imaginary baryonic chemical potential is introduced. As a result, we can consider the torus, which is characterized by the complex number densities of baryons (antibaryons) and quarks (antiquarks). We apply this model to analyze the Roberge-Weiss transition. It is shown that the torus vanishes at the baryonic chemical potential where the Roberge-Weiss transition appears because the number density of baryons (antibaryons) is not linearly independent of the number density of quarks (antiquarks). When the temperature T is lower than the Roberge-Weiss transition temperature TRW, the torus shrinks smoothly to the one-dimensional object at the Roberge-Weiss transition point, but the discontinuity does not appear. On the other hand, the discontinuity of the geometrical object appears when T>TRW. We also calculate the modulus of the torus and transform it into the fundamental region. The transformed moduli are symmetric below TRW, but the symmetry is broken above TRW.

    hep-phhep-latnucl-thPRD(2025)·2 citations
20. 20*

    Large $N$-point energy correlator in the collinear limit

    Lin Dai🇨🇳 · Chul Kim🇰🇷 · Adam K. Leibovich🇺🇸

    For the $N$-point energy correlator in the collinear limit, the largest projected angle $R$ in the large $N$ limit can be viewed as the radius of the jet that encompasses all the collinear core particles, while contributions from soft gluons to the radius are suppressed. We relate the $N$-point energy correlator in the large $N$ limit to the moments of the fragmentation functions to a jet, and, using previous work, we compare the difference between jets initiated by heavy quarks and light quarks. This comparison reveals the deadcone effect.

    hep-phPRD(2025)·3 citations
21. 21*

    Recent theoretical developments in quarkonia production in relativistic heavy ion collisions

    Jiaxing Zhao🇩🇪

    Quarkonia are golden probes of heavy ion collisions that have attracted much attention from both experimental and theoretical perspectives. This paper will review recent theoretical studies on quarkonium thermal properties, with a particular focus on the heavy quark finite-temperature potential obtained by Lattice QCD and other approaches. Moreover, it will examine the advancements in the real-time evolution of quarkonia in heavy ion collisions.

    hep-phnucl-thEPJ Web Conf.(2025)·2 citations
22. 22*

    A Study of Decay Rate of Bound Negative Muons

    Jian-Bo Deng🇨🇳 · Miao-Yi Deng🇺🇸 · Shi-Jie Ma🇨🇳 · Rui-Bo Wang🇨🇳 · Qi-Qi Fan🇨🇳 · Peng-Zhang He🇨🇳 · Yi-Peng He🇨🇳 · Shuo-Wen Li🇨🇳 · Xian-Ru Hu🇨🇳

    A number of experiments show that the decay lifetimes of muons bound to atomic nuclei are longer than the decay lifetimes of free muons. In this paper, a scheme of extending quantum mechanics (EQM) is proposed to resolve this problem. The Schr$\ddot{\text{o}}$dinger's equation is obtained to prove the validation of this attempt. The decay ratio of bound muons is also calculated in EQM, and the result is in good agreement with the experimental data.

    hep-ph0 citations
23. 23*

    Non-relativistic neutrinos and the question of Dirac vs. Majorana neutrino nature

    Evgeny Akhmedov🇩🇪

    Finding out if neutrinos are Dirac or Majorana particles is known to be extremely difficult. This is generally believed to be due to the smallness of the neutrino mass compared to typical neutrino energies, and to the fact that in the limit of vanishing mass all distinctions between Dirac and Majorana neutrinos disappear. This, however, does not necessarily mean that for non-relativistic neutrinos distinguishing between them is an easy task. We consider this problem in detail. The issues discussed include the possibilities of studying neutrino nature with non-relativistic neutrinos produced in $\beta$ decay in direct neutrino mass measurement experiments, with relic neutrinos, as well as with slow neutrinos in pair production processes and in scattering, both elastic and inelastic. We also discuss processes allowed for only one of the two neutrino types as a means of uncovering neutrino nature.

    hep-phastro-ph.SRhep-exnucl-ex1 citation
24. 24*

    Cosmic neutrino background detection in the minimally extended Standard Model

    Yuber F. Perez-Gonzalez🇬🇧 · Jack D. Shergold🇪🇸

    We investigate the sensitivity of relic neutrino detection methods within the Standard Model, extended to include right-chiral neutrino singlets with Majorana mass terms. In particular, we study neutrino capture on unstable nuclei, the Stodolsky effect, coherent scattering, and an accelerator experiment. We demonstrate that the sensitivity transitions smoothly between Dirac and Majorana regimes, depending on the scale of lepton number violation. Importantly, neutral current interactions lead to transitions between the light and heavy neutrino states, necessitating the use of a density matrix formalism for accurate sensitivity calculations. As the oldest source of neutrinos in the universe, relic neutrinos would be able to provide an ultimate constraint on the lepton number violating scale, $m_R\gtrsim 10^{-33}\mathrm{eV}$, below which neutrinos would behave as Dirac fermions for all practical purposes.

    hep-phastro-ph.COJCAP(2025)·2 citations
25. 25*

    Model independent bounds on heavy sterile neutrinos from the angular distribution of $\mathbf{B}\to {\mathbf{D}}^{\ast }\mathbf{\ell }\nu$ decays

    Florian U. Bernlochner🇩🇪 · Marco Fedele🇩🇪 · Tim Kretz🇩🇪 · Ulrich Nierste🇩🇪 · Markus T. Prim🇩🇪

    In this paper we study the bounds that can be inferred on New Physics couplings to heavy sterile neutrinos $N$ from the recent measurements performed by the Belle collaboration of the angular analysis of $B\to D^{\ast }\ell {\bar{\nu }}_{\ell }$ decays, with $\ell =e,\mu$. Indeed, a sterile neutrino $N$ may lead to competing $B\to D^{\ast }\ell \bar{N}$ decays and Belle might have measured an incoherent sum of these two independent channels. After reviewing the theoretical formalism required to describe this phenomenon in full generality, we first perform a bump hunt in the $M_{\mathrm{miss}}^2$ Belle distribution to search for evidences of an additional massive neutrino. We found in such a way a small hint at $M_{\mathrm{miss}}^2\sim (350\mathrm{MeV}{)}^2$. However, the Belle angular analysis is sensitive to $N$ masses up to $\mathcal{O}$(50 MeV), preventing us to further inspect this hint. Nevertheless, we study the potential impact of this additional channel in the allowed mass range on the measured angular distributions and extract model-independent bounds on the new-physics couplings which could mediate such an interaction. In particular, in the mass window here inspected, we obtain the most stringent bounds for vector and left-handed scalar operators to date.

    hep-phhep-exJHEP(2025)·12 citations
26. 26*

    Dispersion relations for the hadronic VVA correlator

    Jan Lüdtke🇦🇹 · Massimiliano Procura🇦🇹 · Peter Stoffer🇨🇭

    We derive two types of dispersion relations for the hadronic vector-vector-axial-vector (VVA) correlator: one in generic three-point kinematics with fixed photon virtualities, the second in the kinematic limit of one soft photon. The VVA correlator enters in the electroweak contribution to the muon anomalous magnetic moment and it also emerges as the leading term in the operator-product expansion for hadronic light-by-light scattering in the limit of two large photon momenta. Previously, this correlator was only described in terms of hadronic models. Our new dispersive treatments are in analogy to the established and the newly proposed dispersive approaches to hadronic light-by-light. The VVA correlator allows us to investigate the relation between the two types of dispersion relations in a simpler example and to elucidate the reshuffling of different hadronic contributions in this comparison. As a byproduct, we reduce the theoretical uncertainties on the first-family VVA contribution to the muon anomalous magnetic moment by combining the dispersive representation with both asymptotic and low-energy constraints.

    hep-phhep-exhep-latJHEP(2025)·55 citations
27. 27*

    Pair production with capture by energetic cosmic ray nuclei in a photon background

    AmirFarzan Esmaeili🇧🇷 · Arman Esmaili🇧🇷 · Pasquale Dario Serpico🇫🇷

    We investigate the ionization state of very energetic cosmic ray nuclei in photon fields, such as the cosmic microwave background (CMB) in extragalactic propagation and the environment surrounding the acceleration site in astrophysical sources. We focus on the process of pair production with electron capture (PPC), where the interaction of a single photon with a nucleus produces an $e^{\pm }$ pair (similar to Bethe-Heitler process) with the subsequent capture of electron by the nucleus. This process effectively reduces the nucleus charge by one unit and counteracts the photo-ionization process. We show that during cosmological propagation, where the ultra-high energy cosmic rays interact predominantly with the CMB, ionization dominates over PPC for all the cases of practical interest. However, within the source environment and at sufficiently high energies, ionization and PPC processes can reach an equilibrium, leading to a significant fraction of dressed heavy nuclei. This provides a further limitation to the acceleration of high-$Z$ nuclei to very high energies in environments with hot and dense photon fields.

    hep-phastro-ph.HEPRD(2025)·3 citations
28. 28*

    Black Holes in a Gravitational Field: The Non-linear Static Love Number of Schwarzschild Black Holes Vanishes

    Alex Kehagias🇬🇷 · Antonio Riotto🇨🇭

    We show that the static tidal Love number of Schwarzschild black holes in four dimensions and in the vacuum vanishes at any order in the external tidal force. We also identify the underlying non-linear symmetry which is responsible for this result and becomes manifest when the black hole metric is written in axsymmetric static Weyl coordinates.

    ↳ gr-qchep-phhep-thJCAP(2025)·46 citations
29. 29*

    A Minimal Axio-dilaton Dark Sector

    Adam Smith🇬🇧 · Maria Mylova🇯🇵 · Philippe Brax🇫🇷 · Carsten van de Bruck🇬🇧 · C.P. Burgess🇨🇦 · Anne-Christine Davis🇬🇧

    In scalar-tensor theories it is the two-derivative sigma-model interactions that like to compete at low energies with the two-derivative interactions of General Relativity (GR) $—$ at least once the dangerous zero-derivative terms of the scalar potential are suppressed (such as by a shift symmetry). But nontrivial two-derivative interactions require at least two scalars to exist and so never arise in the single-scalar models most commonly explored. Axio-dilaton models provide a well-motivated minimal class of models for which these self-interactions can be explored. We review this class of models and investigate whether these minimal two fields can suffice to describe both Dark Matter and Dark Energy. We find that they can $—$ the axion is the Dark Matter and the dilaton is the Dark Energy $—$ and that they robustly predict several new phenomena for the CMB and structure formation that can be sought in observations. These include specific types of Dark Energy evolution and small space- and time-dependent changes to particle masses post-recombination that alter the Integrated Sachs-Wolfe effect, cause small changes to structure growth and more.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2025)·30 citations
30. 30*

    Spectrum of high-frequency gravitational waves from graviton bremsstrahlung by the decay of inflaton: case with polynomial potential

    Yiheng Jiang🇯🇵 · Teruaki Suyama🇯🇵

    We study the generation of high-frequency gravitational waves (GWs) through graviton bremsstrahlung during the decay of inflaton in the post-inflationary universe, focusing on scenarios with a polynomial inflaton potential. Two main reheating channels are considered: decays into bosons (spin 0) and fermions (spin $\frac{1}{2}$). We compute the resulting GW spectra from three-body decays, where the inflaton decays into a pair of daughter particles and a graviton. We numerically compute the GW spectra for various polynomial exponents by employing two distinct approaches: one treating the inflaton as a collection of rest particles and the other treating it as a coherently oscillating classical field. In the former approach, only gravitons with energies below half the inflaton mass are produced, while the latter allows for the production of gravitons with arbitrarily high energies when the potential exponent is 4 or greater. This difference arises because the inflaton's oscillations are no longer described by a single harmonic mode but instead consist of infinitely many harmonic modes with different frequencies. As a result, the GW spectrum exhibits multiple peaks, with these peaks being less pronounced for higher powers of the potential. We also examine the dependence of the GW spectrum on the coupling constant between the inflaton and daughter particles. Our findings suggest that future GW detectors targeting GWs in the GHz band, such as resonant cavities, may have the capability to detect these signals, offering potential insights into the reheating phase of the early universe.

    ↳ astro-ph.COgr-qchep-phJCAP(2025)·21 citations
31. 31*

    Towards a classification of UV completable Higgs inflation in metric-affine gravity

    Yusuke Mikura🇯🇵 · Yuichiro Tada🇯🇵

    Towards a classification of UV completable Higgs inflation in the framework of parity-even metric-affine gravity, we investigate the particle spectrum of a deformed theory in the large-$N$ limit. In a simple Higgs inflation model in metric-affine gravity, it is known that its UV cutoff is much smaller than the Planck scale. While it calls for UV completion, a concrete example has not yet been found, even with the large-$N$ limit known as a successful technique to complete an original Higgs inflation defined on the Riemannian geometry. This motivates us to study how small deformation of the simple Higgs inflation affects the emergence and properties of dynamical fields particularly in the large-$N$ limit. As a UV theory has to be free of ghosts or tachyons at least around Minkowski space, we perform the parameter search and find the healthy parameter region where a new heavy particle can propagate without these pathologies.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2025)·3 citations
32. 32*

    Progress on the spectroscopy of lattice gauge theories using spectral densities

    Ed Bennett🇬🇧 · Luigi Del Debbio🇬🇧 · Niccolò Forzano🇬🇧 · Ryan C. Hill🇬🇧 · Deog Ki Hong🇰🇷 · Ho Hsiao🇹🇼 · Jong-Wan Lee🇰🇷 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Alessandro Lupo🇫🇷 · Maurizio Piai🇬🇧 · Davide Vadacchino🇬🇧 · Fabian Zierler🇬🇧

    Spectral densities encode non-perturbative information crucial in computing physical observables in strongly coupled field theories. Using lattice gauge theory data, we perform a systematic study to demonstrate the potential of recent technological advances in the reconstruction of spectral densities. We develop, maintain and make publicly available dedicated analysis code that can be used for broad classes of lattice theories. As a test case, we analyse the Sp(4) gauge theory coupled to an admixture of fermions transforming in the fundamental and two-index antisymmetric representations. We measure the masses of mesons in energy-smeared spectral densities, after optimising the smearing parameters for available lattice ensembles. We present a summary of the mesons mass spectrum in all the twelve (flavored) channels available, including also several excited states.

    ↳ hep-lathep-phPoS(2025)·4 citations
33. 33*

    Quark Gas at High Temperature: Finite-Volume Effects

    R.N. Rogalyov🇷🇺 · N.V. Gerasimeniuk🇷🇺 · A.A. Korneev🇷🇺

    It is shown that the textbook formula for the pressure of free massless fermions leads to negative values of the probability mass function of the distribution of the system of free massless fermions in the fermion number. The ways to resolve this paradox are proposed. A detailed analysis of the corresponding partition function indicates the presence of a Roberge-Weiss transition in the absence of strong interactions.

    ↳ hep-latcond-mat.stat-mechhep-phhep-thPhys.Part.Nucl.(2025)·1 citation
34. 34*

    Progress on pseudoscalar flavour-singlets in Sp(4) with mixed fermion representations

    Fabian Zierler🇬🇧 · Ed Bennett🇬🇧 · Niccolò Forzano🇬🇧 · Deog Ki Hong🇰🇷 · Ho Hsiao🇹🇼 · Jong-Wan Lee🇰🇷 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Maurizio Piai🇬🇧 · Davide Vadacchino🇬🇧

    We measure the masses of the pseudoscalar flavour-singlet meson states in the $Sp(4)$ gauge theory coupled to two Dirac fermions transforming in the fundamental representation and three Dirac fermions in the antisymmetric representation. This theory provides a compelling ultraviolet completion for the minimal composite Higgs model implementing also partial compositeness for the top quark. The spectrum contains two, comparatively light, pseudoscalar flavour-singlet states, which mix with one another. One of them is a Nambu-Goldstone boson (in the massless limit), whereas the other receives a mass from the $U(1{)}_A$ axial anomaly. We demonstrate how to measure the mixing between these two states. For moderately heavy fermion masses, we find that the two wave functions are dominated by one of the fermion representations, mixing effects being small.

    ↳ hep-lathep-phPoS(2025)·3 citations
35. 35*

    Inflationary and Gravitational Wave Signatures of Small Primordial Black Holes as Dark Matter

    Will Barker🇨🇿 · Benjamin Gladwyn🇬🇧 · Sebastian Zell🇧🇪

    Mounting evidence suggests that the semi-classical description of a black hole breaks down at the latest after losing an O(1) fraction of its mass. As a result, effects such as memory burden can slow down evaporation so that small primordial black holes (PBHs), in particular those in the mass range 10^6 g to 10^9 g, become viable dark matter candidates. In this paper, we investigate the production of PBHs from a prototype model of polynomial inflation with a non-minimal coupling to gravity. We show that a sufficiently small PBH mass alleviates any tension with CMB observations. Moreover, we develop efficient numerical procedures to identify model parameters and evolve Mukhanov-Sasaki modes to place bounds on the scalar-induced stochastic gravitational wave (GW) background. Whilst we identify some prospects for observation with future GW detectors, our results highlight the need to develop new experiments for high-frequency GW detection in the ~kHz to ~MHz range. Finally, we demonstrate that previously-used ansätze for modelling the power spectrum only yield a reliable approximation for the GW signal if some input from inflation is used.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2025)·31 citations
36. 36*

    Superradiance of charged black holes embedded in dark matter halos

    Alessandro Mollicone🇮🇹 · Kyriakos Destounis🇮🇹

    Astrophysical environments are ubiquitous in the Universe; from accretion disks around black holes to galactic dark matter halos, distributions of astrophysical material veil the vast majority of Cosmos. Including environmental effects in strong-field gravity and astrophysics is, therefore, a rather tantalizing task in the quest for novel gravitational-wave phenomena. Here, we examine how environments affect the high-energy process of superradiance. In particular, we study the amplification of charged scalar waves under the expense of the electrostatic energy contained in a charged black hole that is embedded in an observationally-motivated, and qualitatively generic, dark matter halo. We find that the superradiant amplification of massless charged scalar fields scattering off environmentally-enriched charged black holes can be equally efficient to those occurring in vacuum charged black holes. This occurs due to the fact that the sole interplay between the scalar wave and the black hole is the electromagnetic interaction. The addition of mass on the charged scalar waves leads to a rapid suppression of superradiant amplification. This transpires to a great extent due to the `friction' that the mass introduces to the black hole potential. Nevertheless, for sufficiently large scalar masses, the amplification factors can be also subdominantly affected by the compactness of the halo. This occurs because the gravitational interaction between the dense halo and the wave's mass grows, thus further suppressing the superradiant amplification.

    ↳ gr-qcastro-ph.GAastro-ph.HEhep-ph+1PRD(2025)·37 citations
37. 37*

    First constraints on general neutrino interactions based on KATRIN data

    M. Aker🇩🇪 · D. Batzler🇩🇪 · A. Beglarian🇩🇪 · J. Beisenkötter🇩🇪 · M. Biassoni🇮🇹 · B. Bieringer🇩🇪 · Y. Biondi🇩🇪 · F. Block🇩🇪 · B. Bornschein🇩🇪 · L. Bornschein🇩🇪 · M. Böttcher🇩🇪 · M. Carminati🇮🇹 and 121 other authors

    The precision measurement of the tritium $\beta$-decay spectrum performed by the KATRIN experiment provides a unique way to search for general neutrino interactions (GNI). All theoretical allowed GNI terms involving neutrinos are incorporated into a low-energy effective field theory, and can be identified by specific signatures in the measured tritium $\beta$-spectrum. In this paper an effective description of the impact of GNI on the $\beta$-spectrum is formulated and the first constraints on the effective GNI parameters are derived based on the 4 million electrons collected in the second measurement campaign of KATRIN in 2019. In addition, constraints on selected types of interactions are investigated, thereby exploring the potential of KATRIN to search for more specific new physics cases, including a right-handed W boson, a charged Higgs or leptoquarks.

    ↳ nucl-exhep-exhep-phPRL(2025)·12 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.