Tue·Apr 30, 2024Tuesday·April 30, 2024

1. 01*

   The properties of $\varphi (2170)$ and its three-body nature

   A. Martinez Torres🇧🇷 · Brenda B. Malabarba🇧🇷 · K. P. Khemchandani🇧🇷

   We summarize the results we obtained for the partial decay widths of $\varphi (2170)$ into two-body final states formed by a $\bar{K}$ and a Kaonic resonance, like $K(1460)$, $K_1(1270)$, as well as to final states constituted by a $\varphi$ and an $\eta /{\eta }^{\prime }$ mesons. The results obtained are compared with the values extracted from experimental data on the corresponding branching ratios, which were determined by the BESIII collaboration. A reasonable agreement is found, which together with the previous reproduction of the mass, width, and cross section for the process $e^{+}{e}^{-}\to \varphi f_0$ strongly indicates the molecular nature of $\varphi (2170)$ as a $\varphi K\bar{K}$ system.

   hep-phnucl-thEPJ Web Conf.(2024)·1 citation
2. 02*

   Predicting possible molecular states of nucleons with ${\Xi }_c$, ${\Xi }_c^{\ast }$, and ${\Xi }_c^{\prime }$

   Jin-Yu Huo🇨🇳 · Li-Cheng Sheng🇨🇳 · Rui Chen🇨🇳 · Xiang Liu🇨🇳

   In the framework of a one-boson-exchange model, we carry out a comprehensive investigation of the ${\Xi }_{c}N/{\Lambda }_c\Sigma /{\Xi }_c^{\prime }N/{\Sigma }_c\Lambda /{\Xi }_c^{\ast }N/{\Sigma }_c^{\ast }\Lambda /{\Sigma }_c\Sigma /{\Sigma }_c^{\ast }\Sigma$ interactions. We consider the $S$-$D$-wave mixing effects and the coupled-channel effects to derive the relevant effective potentials. Our results can predict several possible charm-strange deuteronlike ${\Xi }_c^{{(}^{\prime },\ast )}N$ hexaquarks, the ${\Xi }_c^{\prime }N$ molecules with $I(I^P)=0(0^{+})$, $0(1^{+})$, $1(1^{+})$, the ${\Xi }_c^{\ast }N$ molecules with $0(1^{+})$, $0(2^{+})$, $1(2^{+})$, and the coupled ${\Xi }_{c}N/{\Xi }_c^{\prime }N/{\Xi }_c^{\ast }N/{\Sigma }_c\Sigma /{\Sigma }_c^{\ast }\Sigma$ molecule with $0(1^{+})$. We expect the experiments to search for our predictions of the ${\Xi }_c^{(\prime ,\ast )}N$ bound states.

   hep-phPRD(2024)·3 citations
3. 03*

   Wide Binary Evaporation by Dark Solitons: Implications from the GAIA Catalog

   Qiming Qiu🇨🇳 · Yu Gao🇨🇳 · Haijun Tian🇨🇳 · Kechen Wang🇨🇳 · Zihang Wang🇨🇳 · Xiangming Yang🇨🇳

   An analytic calculation is given for binary star evaporation under the tidal perturbation from randomly distributed, spatially extended dark objects. In particular, the Milky Way's wide binary star population is susceptible to such disruption from dark matter solitons of comparable and larger sizes. We identify high-probability `halo-like' wide binaries in GAIA EDR3 with separations larger than 0.1 parsec. Survival of the farthest-separated candidates will provide a novel gravitational probe to dark matter in the form of solitons. In the case of dilute axion-like boson stars, the observational sensitivity extends into the axion mass range $m_a\sim 10^{-17}-10^{-15}$ eV.

   hep-phastro-ph.HEJCAP(2025)·8 citations
4. 04*

   Unitarity implications of ${\tilde{F}}_{\mu \nu }$ and $F_{\mu \nu }$ models with LIV in $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$

   Alessio T. B. Celeste🇧🇷 · Adriano M. Santos🇧🇷

   We studied two different models that included Lorentz Invariance Violation coupling in the scattering processes of $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$. We found that using the model with the dual electromagnetic tensor ${\tilde{F}}_{\mu \nu }$ resulted in violations of unitarity in both vector and axial scenarios. On the other hand, using the model with nonminimal coupling with $F_{\mu \nu }$ preserved unitarity in both vector and axial cases. As a result, this could have significant implications, given that the nonminimal coupling model with the dual electromagnetic tensor ${\tilde{F}}_{\mu \nu }$ appeared to be potentially superior to the electromagnetic tensor $F_{\mu \nu }$. Therefore, we believe that these findings could provide a valuable guide for further exploration into the study of CPT and Lorentz breaking phenomena, with significant implications that are certainly nontrivial.

   hep-phhep-thEPJC(2025)·1 citation
5. 05*

   Exploring Transport Properties of Quark-Gluon Plasma in Flavor-Dependent Systems with a Holographic Model

   Bing Chen🇨🇳 · Xun Chen🇨🇳 · Xiaohua Li🇨🇳 · Zhou-Run Zhu🇨🇳 · Kai Zhou🇩🇪

   Based on the holographic model, which incorporates the equation of state (EoS) and baryon number susceptibility for different flavors, we calculate the drag force, jet quenching parameter, and diffusion coefficient of the heavy quark at finite temperature and chemical potential. The holographic results for the diffusion coefficient align with lattice data for $N_f=0$ and $N_f=2+1$, falling within their error margins. The holographic diffusion coefficient for heavy quark in the systems of different flavors \textcolor{red}{is compatible with estimates from ALICE data.} The jet quenching parameter in our model demonstrates strong consistency \textcolor{red}{with the estimations obtained from Bayesian analysis of data from both RHIC and LHC for different flavors.} We can confirm the model provides a good description of the transport properties of QGP. The work reinforces the potential of bottom-up holographic model in advancing our understanding of transport properties of hot and dense quark-gluon plasma.

   hep-phPRD(2025)·31 citations
6. 06*

   Constraints on electrophilic scalar coupling from rotating magnetized stars and effects of cosmic neutrino background

   Gaetano Lambiase🇮🇹 · Tanmay Kumar Poddar🇮🇹

   An ultralight electrophilic scalar field can produce a long-range Yukawa-like spatial profile around a rotating, magnetized star when coupled to the constant number density of electrons in either the magnetosphere or the star itself. This long-range scalar field generates an effective scalar charge in the star or its magnetosphere, leading to a long-range force between two compact stars in a binary system. The electrophilic scalar can also radiate from isolated pulsars or double pulsar binary systems. Using the Crab pulsar and PSR J0737-3039A/B as test cases, we derive constraints on the scalar-electron coupling by analyzing observations of long-range force, orbital period decay in binary systems, and pulsar spin-down rates. Among these, the most stringent limits on the coupling are obtained from the orbital period decay. However, these constraints can be significantly reduced if the scalar interacts with the pervasive cosmic neutrino background. Enhancing experimental sensitivity and studying compact objects with stronger magnetic fields and higher angular velocities could further strengthen these bounds.

   hep-phastro-ph.COgr-qcPRD(2025)·7 citations
7. 07*

   CP violation in the CKM mixing for degenerate quark masses

   Ying Zhang🇨🇳

   CP violation in the CKM mixing is discussed for the case of quark mass degeneracy that is approximate in the quark mass hierarchy limit. Differing from the traditional understanding of CP vanishing for degenerate masses, we find degenerate symmetry plays a non-trivial role in CP violation. The minimal flavor structure model is reviewed to demonstrate the role of degenerate symmetry in quark flavor mixing, particularly in CP violation. This relation between mass hierarchy and CP violation helps us understand the origin of CP violation and assists the construction of the flavor model.

   hep-phChin.J.Phys.(2024)·3 citations
8. 08*

   Detailed derivation of the ${}^3{\mathbf{P}}_0$ strong decay model applied to baryons

   T. Aguilar🇪🇨 · A. Capelo-Astudillo🇪🇨 · M. Conde-Correa🇪🇨 · A. Duenas-Vidal🇪🇨 · P. G. Ortega🇪🇸 · J. Segovia🇪🇸

   We provide an in-detail derivation through the ${}^3{P}_0$ pair creation model of the transition matrix for a baryon decaying into a meson-baryon system. The meson's analysis was conducted in Ref. [1] and we extend the same formalism to the baryon sector, focusing on the $\Delta (1232)\to \pi N$ strong decay width because all hadrons involved in the reaction are very well established, the two hadrons in the final state are stable, avoiding further analysis, all quarks are light and so equivalent, and the decay width of the process is relatively well measured. Taking advantage of a Gaussian expansion method for the hadron's radial wave functions, the expression of the invariant matrix element can be related with the mean-square radii of hadrons involved in the decay. We use their experimental measures in such a way that only the strength of the quark-antiquark pair creation from the vacuum is a free parameter. This is then taken from our previous study of strong decay widths in the meson sector, obtaining a quite compatible result with experiment for the calculated $\Delta (1232)\to \pi N$ decay width.

   hep-phhep-exhep-latnucl-ex+1CPC(2025)·1 citation
9. 09*

   Light tetraquark states with exotic quantum numbers $J^{PC}=2^{+-}$

   Qi-Nan Wang🇨🇳 · Ding-Kun Lian🇨🇳 · Wei Chen🇨🇳

   We study the masses of light tetraquark states $ud\bar{u}\bar{d}$ , $us\bar{u}\bar{s}$ and $ss\bar{s}\bar{s}$ with exotic quantum numbers $J^{PC}=2^{+-}$ using the method of QCD sum rules. It is found that there is no tetraquark operator with two Lorentz indices coupling to the $2^{+-}$ quantum numbers. To investigate such tetraquark states, we construct the interpolating tetraquark currents with three Lorentz indices and without derivative operator. We calculate the correlation functions up to dimension 10 condensates, and extract the $2^{+-}$ invariant functions via the projector operator. Our results show that the masses of the $ud\bar{u}\bar{d}$, $us\bar{u}\bar{s}$ and $ss\bar{s}\bar{s}$ tetraquark states with $J^{PC}=2^{+-}$ are about $3.3-3.5\mathrm{GeV}$, $3.5-3.7\mathrm{GeV}$ and $3.67\mathrm{GeV}$, respectively. We further discuss the strong decays of these light tetraquarks into the two-meson and baryon-antibaryon final states, and suggest to search for them in the $\rho \pi ,\omega \pi ,\varphi \pi$, $b_1\pi$, $h_1\pi$, $K{\bar{K}}^{\ast },K{\bar{K}}_1$, $\Delta \bar{\Delta }$, ${\Sigma }^{\ast }{\bar{\Sigma }}^{\ast }$, ${\Xi }^{\ast }{\bar{\Xi }}^{\ast }$, $\Omega \bar{\Omega }$ channels in the future.

   hep-phhep-exPRD(2024)·5 citations
10. 10*

    Controlling the Flavour Changing Neutral Couplings of Multi-Higgs Doublets Models through Unitary Matrices

    João M. Alves🇪🇸

    In this paper, we introduce Unitary Flavour Violation to produce Multi-Higgs Doublets Models where all flavour parameters are contained within three unitary matrices. After that, we identify two of its subclasses, the left and right models, which have naturally suppressed tree-level Flavour Changing Neutral Couplings that easily avoid the experimental constraints derived from neutral meson mixing. Then, we show that left models can accomodate spontaneous CP violation when all quarks have Flavour Changing Neutral Couplings. Finally, we illustrate these concepts by considering a specific implementation with three Higgs doublets.

    hep-phEPJC(2024)·1 citation
11. 11*

    Femtoscopy can tell whether $Z_c(3900)$ and $Z_{cs}(3985)$ are resonances or virtual states

    Zhi-Wei Liu🇨🇳 · Jun-Xu Lu🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳

    There have been extended and heated discussions on the nature of the two exotic states, $Z_c(3900)$ and $Z_{cs}(3985)$, particularly whether they are near-threshold resonances, virtual states, or bound states. In this work, we demonstrate for the first time that the femtoscopic technique can be employed to distinguish between these three scenarios. More concretely, based on the Koonin-Pratt formula with a Gaussian source, we show that the low-momentum $D^0{D}^{\ast -}$/$D^0{D}_s^{\ast -}$ correlation functions significantly differ in the three scenarios. The high-momentum results exhibit distinct characteristics in the resonant and virtual state scenarios, especially in small collision systems of 1 fm, as produced in $pp$ collisions at the LHC. We hope that these discoveries will stimulate further experimental studies and help clarify the nature of the many exotic states that have been discovered.

    hep-phhep-exnucl-exnucl-thSci.Bull.(2025)·36 citations
12. 12*

    Mass Spectra of $\Xi$ and $\Omega$ Baryons using hypercentral Constituent Quark Model

    Chandni Menapara🇮🇳 · Ajay Kumar Rai🇮🇳

    Hadron spectroscopy is an important tool towards the study of internal quark dynamics in a composite system. The present article focuses on the study of resonance spectra of strange baryons with S=-2, -3. The non-relativistic approach utilizes screened potential as hypercentral one to obtain masses. The spin-dependent part for all possible hyperfine states has been incorporated.

    hep-phnucl-thNuovo Cim.C(2024)·2 citations
13. 13*

    Bayesian Active Search on Parameter Space: a 95 GeV Spin-0 Resonance in the ($B-L$)SSM

    Mauricio A. Diaz🇬🇧 · Giorgio Cerro🇬🇧 · Srinandan Dasmahapatra🇬🇧 · Stefano Moretti🇬🇧

    In the attempt to explain possible data anomalies from collider experiments in terms of New Physics (NP) models, computationally expensive scans over their parameter spaces are typically required in order to match theoretical predictions to experimental observations. Under the assumption that anomalies seen at a mass of about 95 GeV by the Large Electron-Positron (LEP) and Large Hadron Collider (LHC) experiments correspond to a NP signal, which we attempt to interpret as a spin-0 resonance in the $(B-L)$ Supersymmetric Standard Model ($(B-L)$SSM), chosen as an illustrative example, we introduce a novel Machine Learning (ML) approach based on a multi-objective active search method, called b-CASTOR, able to achieve high sample efficiency and diversity, due to the use of probabilistic surrogate models and a volume based search policy, outperforming competing algorithms, such as those based on Markov-Chain Monte Carlo (MCMC) methods.

    hep-phSciPost Phys.Core(2025)·25 citations
14. 14*

    A semi-analytical $x$-space solution for parton evolution -- Application to non-singlet and singlet DGLAP equation

    Juliane Haug🇩🇪 · Oliver Schüle🇩🇪 · Fabian Wunder🇩🇪

    We present a novel semi-analytical method for parton evolution. It is based on constructing a family of analytic functions spanning $x$-space which is closed under the considered evolution equation. Using these functions as a basis, the original integro-differential evolution equation transforms into a system of coupled ordinary differential equations, which can be solved numerically by restriction to a suitably chosen finite subsystem. The evolved distributions are obtained as analytic functions in $x$ with numerically obtained coefficients, providing insight into the analytic behavior of the evolved parton distributions. As a proof-of-principle, we apply our method to the leading order non-singlet and singlet DGLAP equation. Comparing our results to traditional Mellin-space methods, we find good agreement. The method is implemented in the code $\text{POMPOM}$ in $\text{Mathematica}$ as well as in $\text{Python}$.

    hep-phJHEP(2024)·1 citation
15. 15*

    Detectability of the Phase Transition Gravitational Waves in the DFSZ axion Model

    Aidi Yang🇨🇳 · Fa Peng Huang🇨🇳

    In recent years, an increasing number of studies have focused on using gravitational waves to explore axions and the dynamics of Peccei-Quinn symmetry breaking at high energy scales in the early universe. To accurately quantify the capability of specific gravitational wave experiments to probe the axion properties, it is crucial to perform precise calculations of gravitational wave signals based on given axion models and to conduct detailed detectability analysis tailored to the experimental configurations. Therefore, in this work, we consider the widely-studied DFSZ axion model and, for the first time, perform precise calculations of the phase transition dynamics parameters and associated gravitational wave signals. Our results demonstrate that the DFSZ model allows a strong first-order phase transition for the Peccei-Quinn symmetry-breaking process at high energy scales exceeding $10^9\mathrm{GeV}$. Moreover, by calculating the signal-to-noise ratio of the gravitational waves and comparing it with the thresholds of the Cosmic Explorer detector, we find that these signals are observable by the Cosmic Explorer with the energy scale range from $10^9\mathrm{GeV}$ to $10^{12}\mathrm{GeV}$. Notably, through Fisher Matrix analysis, we find that if Cosmic Explorer detectors observe these gravitational waves, the bubble wall velocity will be the first parameter to be determined. This study demonstrates that gravitational wave detection offers a powerful approach to investigating axion dynamics complementary to other experiments.

    hep-phJCAP(2025)·3 citations
16. 16*

    Classical Casimir pressure in the presence of axion dark matter

    Philippe Brax🇫🇷 · Pierre Brun🇫🇷

    We study the effects of an oscillating axion field on the pressure between two metallic plates. We consider the situation where a magnetic field parallel to the plates is present and show that the electric field induced by the coupling of the axion to photons leads to resonances. When the boundary plates are perfect conductors, the resonances are infinitely thin whilst they are broadened when the conductivity of the boundary plates is taken into account. The resonances take place at the tower of distances close to dn = (2n+1){\pi}/m where m is the axion mass and have a finite width and height depending on the conductivity. The resulting resonant pressure on the plate depends on the induced polarisation at the surface of the plates. We investigate the reach of future Casimir experiments in terms of the axion mass and the conductivity of the boundary plates. We find that for large enough conductivities, the axion-induced pressure could be larger than the quantum Casimir effect between the plates.

    hep-phPRD(2024)·2 citations
17. 17*

    Diffusion coefficient matrix for multiple conserved charges: a Kubo approach

    Sourav Dey🇮🇳 · Amaresh Jaiswal🇮🇳 · Hiranmaya Mishra🇮🇳

    The strongly interacting matter created in relativistic heavy-ion collisions possesses several conserved quantum numbers, such as baryon number, strangeness, and electric charge. The diffusion process of these charges can be characterized by a diffusion matrix that describes the mutual influence of the diffusion of various charges. We derive the Kubo relations for evaluating diffusion coefficients as elements of a diffusion matrix. We further demonstrate that in the weak coupling limit, the diffusion matrix elements obtained through Kubo relations reduce to those obtained from kinetic theory with an appropriate identification of the relaxation times. We illustrate this evaluation in a toy model of two interacting scalar fields with two conserved charges.

    hep-phhep-thnucl-thJHEP(2024)·10 citations
18. 18*

    The Landscape of Unfolding with Machine Learning

    Nathan Huetsch🇩🇪 · Javier Mariño Villadamigo🇩🇪 · Alexander Shmakov🇺🇸 · Sascha Diefenbacher🇺🇸 · Vinicius Mikuni🇺🇸 · Theo Heimel🇩🇪 · Michael Fenton🇺🇸 · Kevin Greif🇺🇸 · Benjamin Nachman🇺🇸 · Daniel Whiteson🇺🇸 · Anja Butter🇩🇪 · Tilman Plehn🇩🇪

    Recent innovations from machine learning allow for data unfolding, without binning and including correlations across many dimensions. We describe a set of known, upgraded, and new methods for ML-based unfolding. The performance of these approaches are evaluated on the same two datasets. We find that all techniques are capable of accurately reproducing the particle-level spectra across complex observables. Given that these approaches are conceptually diverse, they offer an exciting toolkit for a new class of measurements that can probe the Standard Model with an unprecedented level of detail and may enable sensitivity to new phenomena.

    hep-phcs.LGhep-exSciPost Phys.(2025)·53 citations
19. 19*

    NNLL-fast 2.0: Coloured Sparticle Production at the LHC Run 3 with $\sqrt{S}$ = 13.6 TeV

    Wim Beenakker🇳🇱 · Christoph Borschensky🇩🇪 · Michael Krämer🇩🇪 · Anna Kulesza🇩🇪 · Eric Laenen🇳🇱 · Judita Mamužić🇪🇸 · Laura Moreno Valero🇩🇪

    We report on updated precision predictions for total cross sections of coloured supersymmetric particle production at the LHC with a centre-of-mass energy of $\sqrt{S}$ = 13.6 TeV, computed with the modern PDF4LHC21 set. The cross sections are calculated at an approximated NNLO accuracy in QCD and contain corrections from the threshold resummation of soft-gluon emission up to NNLL accuracy as well as Coulomb-gluon contributions including bound-state terms. The corrections are found to increase the cross sections and reduce the theoretical uncertainty as compared to the best available fixed-order calculations. These predictions constitute the state-of-the-art calculations and update the existing results for $\sqrt{S}$ = 13 TeV. We make our new results publicly available in the version 2.0 update to the code package NNLL-fast.

    hep-phhep-exSciPost Phys.Core(2024)·14 citations
20. 20*

    Twist analysis of the spin-orbit correlation in QCD

    Yoshitaka Hatta🇺🇸 · Jakob Schoenleber🇺🇸

    We present a QCD analysis of the twist-three parton distribution functions associated with the spin-orbit correlation of quarks and gluons in spin-$\frac{1}{2}$ and spin-0 hadrons. We derive exact non-perturbative identities decomposing the spin-orbit correlations into the Wandzura-Wilczek part and the genuine twist-three part. In the spin-$\frac{1}{2}$ case, the result is partially related to the kinematical twist-three part of the $g_T(x)$ distribution familiar in the context of transverse spin physics. We use these identities to obtain a novel longitudinal momentum sum rule which may be regarded as the momentum version of the Jaffe-Manohar spin sum rule. We explore the physical interpretation of the sum rule and make a connection to the color Lorentz forces and their associated potential energies.

    hep-phJHEP(2024)·14 citations
21. 21*

    The ${\Omega }_c\to {\pi }^{+}({\pi }^0,\eta )\pi {\Xi }^{\ast }$ reactions and the two $\Xi (1820)$ states

    Wei-Hong Liang🇨🇳 · Raquel Molina🇪🇸 · Eulogio Oset🇪🇸

    We have studied the ${\Omega }_c\to {\pi }^{+}({\pi }^0,\eta )\pi {\Xi }^{\ast }$ decays, where the final $\pi {\Xi }^{\ast }$ comes from the decay of two resonances around the nominal $\Xi (1820)$, which are generated from the interaction of coupled channels made of a pseudoscalar and a baryon of the decuplet. The $\pi {\Xi }^{\ast }$ mass distributions obtained in the six different reactions studied are quite different and we single out four of them, which are free of a tree level contribution, showing more clearly the effect of the resonances. The lower mass resonance is clearly seen as a sharp peak, but the higher mass resonance manifests itself through an interference with the lower one that leads to a dip in the mass distribution around $1850\mathrm{MeV}$. Such a feature is similar to the dip observed in the $s$-wave $\pi \pi$ cross section around the $980\mathrm{MeV}$ coming from the interference of the $f_0(500)$ and $f_0(980)$ resonances. Its observation in coming upgrades of present facilities will shed light on the existence of these two resonances and their nature.

    hep-phPRD(2024)·5 citations
22. 22*

    Studies of $T_{cc}^{+}$ Decays and Transverse-Momentum-Dependent $J/\psi$ Production Using Effective Field Theory

    Reed Hodges🇺🇸

    We describe the application of effective field theories for quantum chromodynamics (QCD) to two bound states involving heavy quarks: the $T_{cc}^{+}$ exotic meson and the $J/\psi$. We study the decay of the $T_{cc}^{+}$ in an effective theory for hadronic molecules, and find agreement with experiment. We also use the nonrelativistic QCD (NRQCD) factorization formalism to derive the leading-order transverse momentum dependent fragmentation functions (FFs) for quarks and gluons fragmenting to $J/\psi$. We then make use of these TMD FFs to compare the $J/\psi$ production mechanisms of light quark fragmentation and photon-gluon fusion, where the conclusions we draw can motivate future experiments at the Electron Ion Collider, shedding light on the inner structure of nucleons and testing ideas from NRQCD factorization. These results showcase the utility of effective field theories in explaining experiments and testing key concepts in nuclear/particle physics.

    hep-ph5 citations
23. 23*

    Photon frequency variation in non-linear electro-magnetism

    Alessandro D.A.M. Spallicci🇫🇷 · Abedennour Dib🇫🇷 · José A. Helayël-Neto🇧🇷

    We set a generalised non-linear Lagrangian, encompassing Born-Infeld and Heisenberg-Euler theories among others. The Lagrangian reduces to the Maxwell Lagrangian at lowest order. The field is composed by a propagating light-wave in an electro-magnetic background. The wave exhibits energy variation when the background is space-time dependent. In the photon description, this implies a red or a blue shift, like what we obtained in massive theories, as the de Broglie-Proca or effective mass theories as the Standard-Model Extension under Lorentz symmetry violation. The two results, photon energy-conservation and the frequency shift are instead new for non-linear electro-magnetism. We conclude by discussing how these static frequency shifts when added to the expansion red shift allow new interpretations in cosmology or for atomic spectra. We finally consider the consequences on the Poincaré symmetry.

    hep-phastro-ph.COgr-qchep-thPLB(2024)·5 citations
24. 24*

    Unifying Simulation and Inference with Normalizing Flows

    Haoxing Du🇺🇸 · Claudius Krause🇩🇪 · Vinicius Mikuni🇺🇸 · Benjamin Nachman🇺🇸 · Ian Pang🇺🇸 · David Shih🇺🇸

    There have been many applications of deep neural networks to detector calibrations and a growing number of studies that propose deep generative models as automated fast detector simulators. We show that these two tasks can be unified by using maximum likelihood estimation (MLE) from conditional generative models for energy regression. Unlike direct regression techniques, the MLE approach is prior-independent and non-Gaussian resolutions can be determined from the shape of the likelihood near the maximum. Using an ATLAS-like calorimeter simulation, we demonstrate this concept in the context of calorimeter energy calibration.

    hep-phhep-exphysics.data-anphysics.ins-det+1PRD(2025)·15 citations
25. 25*

    Alpha radioactivity deep-underground as a probe of axion dark matter

    Carlo Broggini🇮🇹 · Giuseppe Di Carlo🇮🇹 · Luca Di Luzio🇮🇹 · Claudio Toni🇮🇹

    We propose to investigate the time modulation of radioisotope decays deep underground as a method to explore axion dark matter. In this work, we focus on the $\alpha$-decay of heavy isotopes and develop a theoretical description for the $\theta$-dependence of $\alpha$-decay half-lives, which enables us to predict the time variation of $\alpha$-radioactivity in response to an oscillating axion dark matter background. To probe this scenario, we have recently constructed and installed a setup deep underground at the Gran Sasso Laboratory, based on the $\alpha$-decay of Americium-241. This prototype experiment, named RadioAxion-$\alpha$, will allow us to explore a broad range of oscillation's periods, from a micro-second up to one year, thus providing competitive limits on the axion decay constant across 13 orders of magnitude in the axion mass, ranging from $10^{-9}$ eV to $10^{-20}$ eV after one month of data collection, and down to $10^{-22}$ eV after three years.

    hep-phhep-exnucl-exnucl-thPLB(2024)·9 citations
26. 26*

    Next-to-Leading Order Unitarity Fits in the Extended Georgi-Machacek Model

    Debtosh Chowdhury🇮🇳 · Poulami Mondal🇮🇳 · Subrata Samanta🇮🇳

    We compute one-loop corrections to all $2\to 2$ bosonic scattering amplitudes in the generalized two-triplet scalar extension of the Standard Model and place next-to-leading order unitarity bounds on the scalar quartic couplings of the Georgi-Machacek (GM) and the extended Georgi-Machacek (eGM) models. Further, we derive the bounded-from-below (BFB) conditions on the scalar quartic couplings demanding the stability of the scalar potential in the field subspaces. We find that, in the GM and eGM models, the BFB conditions with all combinations of three non-zero scalar fields provide a very good approximation of the all field BFB conditions while being computationally more efficient. With these improved theoretical constraints, we present results for the GM and eGM models from global fits to the latest Higgs signal strength measurements at the $13$ TeV Large Hadron Collider. We observe that the global fit disfavors the regions where ${\kappa }_V>1.05$, ${\kappa }_V<0.95$, and ${\kappa }_f>1.05$, ${\kappa }_f<0.92$ at a $95.4\%$ probability for both models. We obtain an upper limit on the absolute values of the scalar quartic couplings to be $1.91(3.0)$ in the GM (eGM) model. We find that the absolute mass differences between the heavy Higgs bosons are less than $410$ GeV and $520$ GeV in the GM and eGM models, respectively, if their individual masses are restricted to be below $1.1$ TeV.

    hep-phhep-exJ.Phys.G(2026)·12 citations
27. 27*

    Strongly vs. weakly coupled in-medium showers: energy stopping in large-$N_f$ QED

    Peter Arnold🇺🇸 · Omar Elgedawy🇺🇸 · Shahin Iqbal🇵🇰

    Inside a medium, showers originating from a very high-energy particle may develop via medium-induced splitting processes such as hard bremsstrahlung or pair production. During shower development, two consecutive splittings sometimes overlap quantum mechanically, so that they cannot be treated independently. Some of these effects can be absorbed into an effective value of a medium parameter known as $\hat{q}$. Previous calculations (with certain simplifying assumptions) have found that, after adjusting the value of $\hat{q}$, the leftover effect of overlapping splittings is quite small for purely gluonic large-$N_c$ showers but is very much larger for large-$N_f$ QED showers, at comparable values of $N\alpha$. Those works did not quite make for apples-to-apples comparisons: the gluon shower work investigated energy deposition from a gluon-initiated shower, whereas the QED work investigated charge-deposition from an electron-initiated shower. As a first step to tighten up the comparison, this paper investigates energy deposition in the QED case. Along the way, we develop a framework that should be useful in the future to explore whether the very small effect of overlapping splitting in purely gluonic showers is an artifact of having ignored quarks.

    hep-phnucl-thJHEP(2024)·12 citations
28. 28*

    ALP-ine quests at the LHC: hunting axion-like particles via peaks and dips in $t\bar{t}$ production

    Afiq Anuar🇩🇪 · Anke Biekötter🇩🇪 · Thomas Biekötter🇩🇪 · Alexander Grohsjean🇩🇪 · Sven Heinemeyer🇪🇸 · Laurids Jeppe🇩🇪 · Christian Schwanenberger🇩🇪 · Georg Weiglein🇩🇪

    We present an analysis of the sensitivity of current and future LHC searches for new spin-0 particles in top-anti-top-quark ($t\bar{t}$) final states, focusing on generic axion-like particles (ALPs) that are coupled to top quarks and gluons. As a first step, we derive new limits on the effective ALP Lagrangian in terms of the Wilson coefficients $c_t$ and $c_{\tilde{G}}$ based on the results of the CMS search using $35.9$ fb${}^{-1}$ of data, collected at $\sqrt{s}=13$ TeV. We then investigate how the production of an ALP with generic couplings to gluons and top quarks can be distinguished from the production of a pseudoscalar which couples to gluons exclusively via a top-quark loop. To this end, we make use of the invariant $t\bar{t}$ mass distribution and angular correlations that are sensitive to the $t\bar{t}$ spin correlation. Using a mass of 400 GeV as an example, we find that already the data collected during Run 2 and Run 3 of the LHC provides an interesting sensitivity to the underlying nature of a possible new particle. We also analyze the prospects for data anticipated to be collected during the high-luminosity phase of the LHC. Finally, we compare the limits obtained from the $t\bar{t}$ searches to existing experimental bounds from LHC searches for narrow di-photon resonances, from measurements of the production of four top quarks, and from global analyses of ALP-SMEFT interference effects.

    hep-phJHEP(2024)·22 citations
29. 29*

    Ricci Reheating on the Lattice

    Daniel G. Figueroa🇪🇸 · Toby Opferkuch🇮🇹 · Ben A. Stefanek🇬🇧

    We study the dynamics of a non-minimally coupled (NMC) scalar spectator field in non-oscillatory inflationary scenarios, where there is a transition from inflation to kination domination (KD). Engineering a realistic finite-duration transition through a CMB-compatible inflaton potential, we calculate the initial tachyonic growth of the NMC field during KD and perform lattice simulations of the subsequent non-linear dynamics. We characterize the regularization effect on the tachyonic growth, either due to self-interactions, or via gravitational backreaction when the NMC field grows to dominate the energy of the universe. Our study provides the first realistic treatment of the dynamics, with significant improvements compared to previous work, where one or more of the following aspects were assumed: ($i$) the background expansion can be neglected during the tachyonic growth, ($ii$) coherence of the NMC field, ($iii$) coherence of the inflaton, ($iv$) instantaneous transition, and ($v$) a KD equation of state of exactly $w=1$. Using our methodology, which requires none of the above assumptions, we determine the conditions to achieve proper reheating, i.e. energetic dominance of the NMC field over the inflaton. We characterize the time and energy scales of the problem, either for backreaction due to self-interactions, or (as a novelty of this work) due to gravitational effects. Finally, we calculate $\mathcal{O}(1)$ lattice correction factors to analytic scaling relations derived by some of us in previous work. This enables simple future studies without the need to run lattice simulations.

    ↳ astro-ph.COhep-ph26 citations
30. 30*

    Contribution to differential ${\pi }^0$ and ${\gamma }_{\mathrm{dir}}$ modification in small systems from color fluctuation effects

    Dennis V. Perepelitsa🇺🇸

    A major complication in the search for jet quenching in proton- or deuteron-nucleus collision systems is the presence of physical effects which influence the experimental determination of collision centrality in the presence of a hard process. For example, in the proton color fluctuation picture, protons with a large Bjorken-$x$ ($x\gtrsim 0.1$) parton interact more weakly with the nucleons in the nucleus, leading to a smaller (larger) than expected yield in large (small) activity events. A recent measurement by PHENIX compared the yield of neutral pion and direct photon production in $d$+Au collisions, under the argument that the photon yields correct for such biases, and the difference between the two species is thus attributable to final-state effects (i.e., jet quenching). The main finding suggests a significant degree of jet quenching for hard processes in small systems. In this paper, I argue that the particular photon and pion events selected by PHENIX arise from proton configurations with significantly different Bjorken-$x$ distributions, and thus are subject to different magnitudes of modification in the color fluctuation model. Using the results of a previous global analysis of RHIC and LHC data, I show that potentially all of the pion-to-photon difference in PHENIX data can be described by a proton color fluctuation picture at a quantitative level before any additional physics from final-state effects is required. This finding reconciles the interpretation of the PHENIX measurement with others at RHIC and LHC, which have found no observable evidence for jet quenching in small systems.

    ↳ nucl-thhep-phnucl-exPRC(2024)·18 citations
31. 31*

    Exploring system size dependence of jet modification in heavy-ion collisions

    Yang He🇨🇳 · Mengxue Zhang🇨🇳 · Maowu Nie🇨🇳 · Shanshan Cao🇨🇳 · Li Yi🇨🇳

    In relativistic heavy-ion collisions, jet quenching in quark-gluon plasma (QGP) has been extensively studied, revealing important insights into the properties of the color deconfined nuclear matter. Over the past decade, there has been a surge of interest in the exploration of QGP droplets in small collision systems like $p$+$p$ or $p$+A collisions driven by the observation of collective flow phenomena. However, the absence of jet quenching, a key QGP signature, in these systems poses a puzzle. Understanding how jet quenching evolves with system size is crucial for uncovering the underlying physics. In this study, we employ the linear Boltzmann transport (LBT) model to investigate jet modification in ${}^{96}$Ru+${}^{96}$Ru, ${}^{96}$Zr+${}^{96}$Zr, and ${}^{197}$Au+${}^{197}$Au collisions at $\sqrt{s_{NN}}=200$ GeV. Our findings highlight the system size sensitivity exhibited by jet nuclear modification factor ($R_{\mathrm{AA}}$) and jet shape ($\rho$), contrasting to the relatively weak responses of jet mass ($M$), girth ($g$) and momentum dispersion ($p_{\mathrm{T}}D$) to system size variations. These results offer invaluable insights into the system size dependence of the QGP properties and await experimental validation at the Relativistic Heavy-Ion Collider.

    ↳ nucl-thhep-phnucl-exPRC(2024)·2 citations
32. 32*

    The Cosmological Impact of Brane-Chern-Simons Massive Gravity

    Sobhan Kazempour🇨🇳 · Amin Rezaei Akbarieh🇮🇷

    In this paper, we present a novel extension of massive gravity theory; the Brane-Chern-Simons massive gravity theory. We explore the cosmological implications of this theory by deriving the background equations and demonstrating the existence of self-accelerating solutions. Interestingly, our theory suggests the existence of self-accelerating mechanisms that originate from an effective cosmological constant, leading to intriguing possibilities for understanding the nature of cosmic acceleration. Furthermore, we perform a tensor perturbation analysis to investigate the propagation of gravitational waves in this framework. We derive the dispersion relation for gravitational waves and study their behavior in the Friedmann-Lemaître-Roberson-Waker cosmology within the context of Brane-Chen-Simons massive gravity. Utilizing the latest Union2 type Ia supernova dataset comprising $557$ SNIa events, we provide observational support for our theoretical framework, indicating that the Brane-Chern-Simons massive gravity theory is consistent with cosmological observations.

    ↳ gr-qchep-phJHEP(2024)·0 citations
33. 33*

    Enhancing dark siren cosmology through multi-band gravitational wave synergetic observations

    Yue-Yan Dong🇺🇸 · Ji-Yu Song🇺🇸 · Shang-Jie Jin🇺🇸 · Jing-Fei Zhang🇺🇸 · Xin Zhang🇺🇸

    Multi-band gravitational-wave (GW) standard siren observations are poised to herald a new era in the study of cosmic evolution. These observations offer higher signal-to-noise ratios and improved localizations compared to those achieved with single-band GW detection, which are crucial for the cosmological applications of dark sirens. In this work, we explore the role multi-band GW synergetic observations will play in measuring cosmological parameters, particularly in comparison with single GW observatory data. We used mock multi-band dark siren data from third-generation GW detectors and the baseline Decihertz Interferometer Gravitational-Wave Observatory to infer cosmological parameters. Our analysis shows that multi-band GW observations significantly improve sky localization accuracy by two to three orders of magnitude over single-band observations, although their impact on luminosity distance error remains limited. This results in a substantial improvement in the constraints on matter density and the Hubble constant, enhancing their constraint precision by $60\%$-$90\%$ and $52\%$-$85\%$, respectively. We conclude that the significant potential of multi-band GW synergistic observations for detecting GW signals and resolving the Hubble tension is highly promising and warrants anticipation.

    ↳ astro-ph.COgr-qchep-phJCAP(2025)·25 citations
34. 34*

    BUFF: Boosted Decision Tree based Ultra-Fast Flow matching

    Cheng Jiang🇬🇧 · Sitian Qian🇨🇳 · Huilin Qu🇨🇭

    Tabular data stands out as one of the most frequently encountered types in high energy physics. Unlike commonly homogeneous data such as pixelated images, simulating high-dimensional tabular data and accurately capturing their correlations are often quite challenging, even with the most advanced architectures. Based on the findings that tree-based models surpass the performance of deep learning models for tasks specific to tabular data, we adopt the very recent generative modeling class named conditional flow matching and employ different techniques to integrate the usage of Gradient Boosted Trees. The performances are evaluated for various tasks on different analysis level with several public datasets. We demonstrate the training and inference time of most high-level simulation tasks can achieve speedup by orders of magnitude. The application can be extended to low-level feature simulation and conditioned generations with competitive performance.

    ↳ physics.ins-detcs.LGhep-exhep-ph+19 citations
35. 35*

    Flow-based Nonperturbative Simulation of First-order Phase Transitions

    Yang Bai🇺🇸 · Ting-Kuo Chen🇺🇸

    We present a flow-based method for simulating and calculating nucleation rates of first-order phase transitions in scalar field theory on a lattice. Motivated by recent advancements in machine learning tools, particularly normalizing flows for lattice field theory, we propose the ``partitioning flow-based Markov chain Monte Carlo (PFMCMC) sampling" method to address two challenges encountered in normalizing flow applications for lattice field theory: the ``mode-collapse" and ``rare-event sampling" problems. Using a (2+1)-dimensional real scalar model as an example, we demonstrate the effectiveness of our PFMCMC method in modeling highly hierarchical order parameter probability distributions and simulating critical bubble configurations. These simulations are then used to facilitate the calculation of nucleation rates. We anticipate the application of this method to (3+1)-dimensional theories for studying realistic cosmological phase transitions.

    ↳ hep-latastro-ph.COhep-phJHEP(2024)·5 citations
36. 36*

    Dressing vs. Fixing: On How to Extract and Interpret Gauge-Invariant Content

    Philipp Berghofer🇦🇹 · Jordan François🇦🇹

    There is solid consensus among physicists and philosophers that, in gauge field theory, for a quantity to be physically meaningful or real, it must be gauge-invariant. Yet, every "elementary" field in the Standard Model of particle physics is actually gauge-variant. This has led a number of researchers to insist that new manifestly gauge-invariant approaches must be established. Indeed, in the foundational literature, dissatisfaction with standard methods for reducing gauge symmetries has been expressed: Spontaneous symmetry breaking is deemed conceptually dubious, while gauge fixing suffers the same limitations and is subject to the same criticisms as coordinate choices in General Relativity. An alternative gauge-invariant proposal was recently introduced in the literature, the so-called "dressing field method" (DFM). It is a mathematically subtle tool, and unfortunately prone to be confused with simple gauge transformations, hence with standard gauge~fixings. As a matter of fact, in the physics literature the two are often conflated, and in the philosophy community some doubts have been raised about whether there is any substantial difference between them. Clarifying this issue is of special significance for anyone interested in both the foundational issues of gauge theories and their invariant formulation. It is thus our objective to establish as precisely as possible the technical and conceptual distinctions between the DFM and gauge fixing.

    ↳ physics.hist-phhep-phFound.Phys.(2024)·17 citations
37. 37*

    Torsion-induced axions in string theory, quantum gravity and the cosmological tensions

    Nick E. Mavromatos🇬🇷 · Panagiotis Dorlis🇬🇷 · Sotirios-Neilos Vlachos🇬🇷

    We discuss the role of torsion in string theory on inducing pseudoscalar degrees of freedom (axions), which in turn couple to (gravitational) Chern-Simons (CS) anomalous terms. Such interactions can induce inflation, of running vacuum type, not requiring external inflaton fields, through condensation of the anomalous terms as a consequence of primordial chiral gravitational-wave (GW) tensor perturbations in a weak-quantum gravity setting. The presence of an UV cutoff for the GW quantum graviton modes opens up the system, leading to a dissipative behaviour realised via the presence of non trivial imaginary parts of the gravitational CS terms. The naive estimate of the life time of inflation based on such imaginary parts, which afflict the pertinent GW Hamiltonian, is quite consistent with the estimates of the duration of inflation based on an analysis of the condensate-induced linear-axion-potential by means of dynamical systems. Such quantum-gravity effects can also contribute positively to the alleviation of cosmological tensions if they survive today. In the talk we discuss the conditions under which such a result may be achieved. We also discuss the potential role of other axions in string theory, coming from compactification, in inducing enhanced densities of primordial black holes during RVM inflation, thereby contributing to significantly increased percentages of these black holes that can play the role of dark matter components. Moreover, under certain circumstances, that we shall discuss in some detail, it is also possible that the initially massless torsion-induced axions can acquire a non-trivial mass during the radiation era, thereby providing additional dark matter components in the Universe. With regards to this aspect, we also emphasise the role of massive right-handed neutrinos, provided that such excitations exist in the relevant spectra.

    ↳ gr-qchep-phhep-thPoS(2024)·11 citations
38. 38*

    "Rosenbluth" separation of the $J/\psi$ near-threshold photoproduction -- an access to the gluon Gravitational Form Factors at high $t$

    Lubomir Pentchev🇺🇸 · Eugene Chudakov🇺🇸

    We perform analysis of the near-threshold $J/\psi$ photoproduction data off the proton based on two theoretical approaches, GPD [1] and holographic [2], that represent the differential cross sections as powers of the skewness parameter with coefficients that depend only on the momentum transfer $t$. This allows to separate kinematically the corresponding coefficient functions, in much the same way as this is done for the electric and magnetic form factors using the Rosenbluth separation. We examine the independence of the extracted functions with the photon beam energy. These functions, under additional assumptions, are related to the proton's gluon Gravitational Form Factors (gGFFs). We compare the extracted functions with lattice calculations of the gGFFs in the region of $0.5<|t|<2$~GeV${}^2$, where they overlap. Such analysis demonstrates the possibility of extracting some combinations of the gGFFs from the data at high $t$, complementary to the lattice calculations available in the low $t$ region. However, higher statistics are needed to more accurately check the predicted scaling behavior of the data and compare with the lattice results, thus testing and comparing the theoretical assumptions used in the GPD and holographic models.

    ↳ nucl-exhep-phPRD(2025)·11 citations
39. 39*

    Weak equivalence principle and nonrelativistic limit of general dispersion relations

    Manuel Hohmann🇪🇪 · Christian Pfeifer🇩🇪 · Fabian Wagner🇵🇱

    We study the weak equivalence principle in the context of modified dispersion relations, a prevalent approach to quantum gravity phenomenology. We find that generic modified dispersion relations violate the weak equivalence principle. The acceleration in general depends on the mass of the test body, unless the Hamiltonian is either two-homogeneous in the test particles' 4-momenta or the corresponding Lagrangian differs from the homogeneous case by a total derivative only. The key ingredient of this calculation is a $3+1$ decomposition of the parametrization invariant relativistic test particle action derived from the dispersion relation. Additionally, we apply a perturbative expansion in the test particle's spatial velocity and the inverse speed of light. To quantify our result, we provide a general formula for the Eötvós factor of modified dispersion relations. As a specific example, we study the point-particle motion determined from the $\kappa$-Poincaré dispersion relation in the bicrossproduct basis. Comparing the ensuing non-vanishing Eötvós factor to recent data from the MICROSCOPE experiment, we obtain a bound of the model parameter $\hat{\Xi }{}^{-1}\ge 10^{15}\mathrm{GeV}/c^2$.

    ↳ gr-qchep-phhep-thPRD(2024)·4 citations
40. 40*

    Disentangling the development of collective flow in high energy proton proton collisions with a multiphase transport model

    Liang Zheng🇨🇳 · Lian Liu🇨🇳 · Zi-Wei Lin🇺🇸 · Qi-Ye Shou🇨🇳 · Zhong-Bao Yin🇨🇳

    In this work, we investigate the collective flow development in high energy proton proton (pp) collisions with a multiphase transport model (AMPT) based on PYTHIA8 initial conditions with a sub-nucleon structure. It is found that the PYTHIA8 based AMPT model can reasonably describe both the charged hadron productions and elliptic flow experimental data measured in pp collisions at $\sqrt{s}=13$ TeV. By turning on the parton and hadron rescatterings in AMPT separately, we find that the observed collective flow in pp collisions is largely developed during the parton evolution, while no significant flow effect can be generated with the pure hadronic rescatterings. It is also shown that the parton escape mechanism is important for describing both the magnitude of the two-particle cumulant and the sign of the four-particle cumulants. We emphasize that the strong mass ordering of the elliptic flow results from the coalescence process in the transport model and can thus be regarded as unique evidence related to the creation of deconfined parton matter in high energy pp collisions.

    ↳ nucl-thhep-phnucl-exEPJC(2024)·11 citations
41. 41*

    Phantom matter: a challenging solution to the cosmological tensions

    Adria Gomez-Valent🇪🇸 · Joan Sola Peracaula🇪🇸

    The idea of composite dark energy (DE) is quite natural since on general grounds we expect that the vacuum energy density (associated with the cosmological term $\Lambda$) may appear in combination with other effective forms of DE, denoted X. Here we deal with model $w$XCDM, a simplified version of the old $\Lambda$XCDM model (Grande et al., 2006), and exploit the possibility that X behaves as `phantom matter' (PM), which appears in stringy versions of the running vacuum model (RVM). Unlike phantom DE, the PM fluid satisfies the strong energy condition like usual matter, hence bringing to bear positive pressure at the expense of negative energy. Bubbles of PM may appear in the manner of a transitory `phantom vacuum' tunneled into the late universe before it heads towards a new de Sitter era, thereby offering a crop field for the growing of structures earlier than expected. Using SNIa, cosmic chronometers, transversal BAO (BAO 2D), LSS data and the full CMB likelihood from Planck 2018, we find that the $H_0$ and growth tensions virtually disappear, provided that BAO 2D are the only source of BAO data used in the fit. In contrast, our preliminary analysis using exclusively anisotropic BAO (BAO 3D) indicates that the ability to ease the $H_0$ tension is significantly reduced as compared to the scenario with BAO 2D, despite the fact that the overall fit to the cosmological data is still better than in the $\Lambda$CDM. Finally, our approach with BAO 2D favors quintessence-like behavior of the DE below $z\simeq 1.5$ at $\gtrsim 3\sigma$ CL, which is compatible with the recent DESI measurements.

    ↳ astro-ph.COgr-qchep-phhep-thApJ(2024)·80 citations
42. 42*

    Building the Blocks of Schwarzschild

    Raphaël Dulac🇫🇷 · Pierre Heidmann🇺🇸

    We demonstrate that the Schwarzschild black hole can be ``resolved'' into bound states of Reissner-Nordström black holes in four dimensions. These bound states closely resemble the Schwarzschild geometry from the asymptotic region up to an infinitesimal distance away from the Schwarzschild horizon. Below this scale, the horizon is replaced by novel spacetime structures supported by intense and entrapped electromagnetic flux. The flux originates from collinear black holes that can be brought arbitrarily close to extremality. We find that the charge distribution follows a universal pattern, with magnitudes scaling proportionally to the total mass and alternating in sign. Moreover, the bound states always have an entropy that constitutes a fraction of the Schwarzschild entropy. Constructed in four dimensions, the black holes are kept apart by struts, for which we analyze tensions and energies. These solutions pave the way for analogous constructions in supergravity and for a brane/anti-brane description of the Schwarzschild black hole in string theory.

    ↳ hep-thgr-qchep-phJHEP(2024)·6 citations
43. 43*

    Neutron stars and the cosmological constant problem

    Giulia Ventagli🇨🇿 · Pedro G. S. Fernandes🇩🇰 · Andrea Maselli🇮🇹 · Antonio Padilla🇬🇧 · Thomas P. Sotiriou🇬🇧

    Phase transitions can play an important role in the cosmological constant problem, allowing the underlying vacuum energy, and therefore the value of the cosmological constant, to change. Deep within the core of neutron stars, the local pressure may be sufficiently high to trigger the QCD phase transition, thus generating a shift in the value of the cosmological constant. The gravitational effects of such a transition should then be imprinted on the properties of the star. Working in the framework of General Relativity, we provide a new model of the stellar interior, allowing for a QCD and a vacuum energy phase transition. We determine the impact of a vacuum energy jump on mass-radius relations, tidal deformability-radius relations, I-Love-Q relations and on the combined tidal deformability measured in neutron star binaries.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2025)·7 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.