Wed·Sep 13, 2023Wednesday·September 13, 2023

1. 01*

   A data-driven and model-agnostic approach to solving combinatorial assignment problems in searches for new physics

   Anthony Badea🇺🇸 · Javier Montejo Berlingen🇪🇸

   We present a novel approach to solving combinatorial assignment problems in particle physics without the need to introduce prior knowledge or assumptions about the particles' decay. The correct assignment of decay products to parent particles is achieved in a model-agnostic fashion by introducing a novel neural network architecture, Passwd-ABC, which combines a custom layer based on attention mechanisms and dual autoencoders. We demonstrate how the network, trained purely on background events in an unsupervised setting, is capable of reconstructing correctly hypothetical new particles regardless of their mass, decay multiplicity and substructure, and produces simultaneously an anomaly score that can be used to efficiently suppress the background. This model allows to extend the suite of searches for localized excesses to include non-resonant particle pair production where the reconstruction of the two resonant masses is thwarted by combinatorics.

   hep-phphysics.comp-phphysics.data-anPRD(2024)·4 citations
2. 02*

   Induced Lorentz Violation on a Moving Braneworld

   Daniel Kabat🇺🇸 · Marcelo Nomura🇺🇸

   We consider a braneworld scenario in which a flat 4-D brane, embedded in $M^{3,1}\times S^1$, is moving on or spiraling around the $S^1$. Although the induced metric on the brane is 4-D Minkowski, the would-be Lorentz symmetry of the brane is broken globally by the compactification. As recently pointed out this means causal bulk signals can propagate superluminally and even backwards in time according to brane observers. Here we consider the effective action on the brane induced by loops of bulk fields. We consider a variety of self-energy and vertex corrections due to bulk scalars and gravitons and show that bulk loops with non-zero winding generate UV-finite Lorentz-violating terms in the 4-D effective action. The results can be accommodated by the Standard Model Extension, a general framework for Lorentz-violating effective field theory.

   hep-phhep-thPRD(2023)·3 citations
3. 03*

   Magnetic and density effects on the nucleon axial coupling

   C. A. Dominguez🇿🇦 · M. Loewe🇨🇱 · C. Villavicencio🇨🇱 · R. Zamora🇨🇱

   Using appropriate QCD finite energy sum rules, we discuss the influence of an external magnetic field and baryonic density on the axial-vector coupling constant $g_A$. This scenario corresponds to a magnetar environment. We found that $g_A$ decreases both as function of the magnetic field strength and the baryonic density. It turns out that at the nuclear density ${\rho }_0$ the axial-vector coupling takes the value $g_A^{\ast }\approx 0.92$. Although $g_A$ decreases in general with the magnetic field intensity, $g_A^{\ast }$ does not change in a relevant way with the magnetic field.

   hep-phnucl-th1 citation
4. 04*

   Low-Energy Supernovae Bounds on Sterile Neutrinos

   Garv Chauhan🇺🇸 · Shunsaku Horiuchi🇺🇸 · Patrick Huber🇺🇸 · Ian M. Shoemaker🇺🇸

   Sterile neutrinos can be produced through mixing with active neutrinos in the hot, dense core of a core-collapse supernova (SN). The standard bounds on the active-sterile mixing (${\sin }^2\theta$) from SN arise from SN1987A energy-loss, requiring $E_{\text{loss}}<10^{52}\mathrm{erg}$. In this work, we discuss a novel bound on sterile neutrino parameter space arising from the energy deposition through its decays inside the SN envelope. Using the observed underluminous SN IIP population, this energy deposition is constrained to be below $\sim 10^{50}\mathrm{erg}$. Focusing on sterile neutrino mixing only with tau neutrino, for heavy sterile masses $m_s$ in the range $100$-$500$ MeV, we find stringent constraints on ${\sin }^2{\theta }_{\tau }$ reaching two orders of magnitude lower than those from the SN1987A energy loss argument, {thereby probing the mixing angles required for Type-I seesaw mechanism}. Similar bounds will also be applicable to sterile mixing only with muons (${\sin }^2{\theta }_{\mu }$).

   hep-phJCAP(2025)·28 citations
5. 05*

   Extracting Kinetic Freeze-out Properties in High Energy Collisions Using a Multi-source Thermal Model

   Jia-Yu Chen🇨🇳 · Mai-Ying Duan🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿

   We study the transverse momentum ($p_T$) spectra of neutral pions and identified charged hadrons produced in proton--proton ($pp$), deuteron--gold ($d$--Au), and gold--gold (Au--Au) collisions at the center of mass energy $\sqrt{s_{NN}}=200$ GeV. The study is made in the framework of a multi-source thermal model used in the partonic level. It is assumed that the contribution to the $p_T$-value of any hadron comes from two or three partons with an isotropic distribution of the azimuthal angle. The contribution of each parton to the $p_T$-value of a given hadron is assumed to obey any one of the standard (Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein) distributions with the kinetic freeze-out temperature and average transverse flow velocity. The $p_T$-spectra of the final-state hadrons can be fitted by the superposition of two or three components. The results obtained from our Monte Carlo method are used to fit the experimental results of the PHENIX and STAR Collaborations. The results of present work serve as a suitable reference baseline for other experiments and simulation studies.

   hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2024)·3 citations
6. 06*

   The Curious Early History of CKM Matrix -- miracles happen!

   Stephen Lars Olsen🇰🇷

   The 1973 Kobayashi Maskawa paper proposed a compelling link between Cabibbo's flavor-mixing scheme and CP violation but, since it required the existence of six quarks at a time when the physics community was happy with only three, it received zero attention. However, two years after the paper appeared -- at which time it had received a grand total of two citations -- the charmed quark was discovered and it finally got some notice and acceptance. After this stumbling start, it subsequently emerged as the focal point of an enormous amount of experimental and theoretical research activity. In an invited talk at a KEK symposium to celebrate the 50th anniversary of the KM paper, I reviewed some of the less well known circumstances that occurred in the years preceding and following the paper's appearance.

   hep-phhep-exPTEP(2025)·2 citations
7. 07*

   QED at NNLO and beyond for precision experiments

   Yannick Ulrich🇬🇧

   Low-energy experiments allow for some of the most precise measurements in particle physics, such as $g-2$. To make the most of these experiments, theory needs to match the experimental precision. Over the last decade, this meant that even in QED next-to-next-to-leading order calculations (or even more in some cases) became necessary. McMule (Monte Carlo for MUons and other LEptons) is a framework that we have developed to obtain NNLO predictions for a number of processes, such as $e\mu \to e\mu$, $ee\to ee$, and $\mu \to e\nu \bar{\nu }$. I will discuss some of the challenges faced when dealing with QED corrections and some possible solutions we have implemented in McMule, namely the subtraction scheme FKS${}^{\ell }$, massification, and next-to-soft stabilisation. I will also demonstrate how to calculate the three-loop massification constant that will be required at N${}^3$LO.

   hep-phPoS(2023)·2 citations
8. 08*

   Muon-electron scattering at NNLO with McMule

   Marco Rocco🇨🇭

   A recently proposed experiment, MUonE, aims to extract the hadronic vacuum polarisation contribution to the muon g-2 from muon-electron scattering at low energy. The extrapolation requires that both experimental and theoretical uncertainties do not exceed 10 ppm. This corresponds, at least, to next-to-next-to-leading-order (NNLO) QED corrections to $e\mu \to e\mu$. I will discuss the implementation of a Monte Carlo integrator for this process in the McMule framework arXiv:2212.06481, which provides infrared-safe differential results at said order in QED. An approximation of the MUonE setup provides some phenomenological results and sheds light on the need for beyond-NNLO corrections, which are currently under study within McMule.

   hep-phPoS(2023)·0 citations
9. 09*

   Direct bounds on Left-Right gauge boson masses at LHC Run 2

   Sergio Ferrando Solera🇪🇸 · Antonio Pich🇪🇸 · Luiz Vale Silva🇪🇸

   While the third run of the Large Hadron Collider (LHC) is ongoing, the underlying theory that extends the Standard Model remains so far unknown. Left-Right Models (LRMs) introduce a new gauge sector, and can restore parity symmetry at high enough energies. If LRMs are indeed realized in nature, the mediators of the new weak force can be searched for in colliders via their direct production. We recast existing experimental bounds from LHC Run 2 on the heavy LRM gauge boson masses. As a novelty, we discuss the effect of the LRM scalar content on the total width of the new gauge bosons, obtaining model-independent bounds within the specific realizations of the LRM scalar sectors analysed here. These bounds avoid the need to detail the spectrum of the scalar sector, and apply in the general case where no discrete symmetry is enforced. Moreover, we emphasize the effect of the structure of the quark right-handed mixing matrix on the charged LRM gauge boson production at LHC. We find that $W_R$ and $Z_R$ masses are constrained to lie above $2$ TeV and $4$ TeV, respectively.

   hep-phhep-exJHEP(2024)·12 citations
10. 10*

    Split gluon masses in $SU(N)\times SU(M)$ theories

    Julia Gómez Concejo🇪🇸 · Felipe J. Llanes-Estrada🇪🇸 · Diego María-Almazán🇪🇸 · Alexandre Salas-Bernárdez🇪🇸

    We extend a known mass-gap equation for pure gluodynamics in global colour models (formulated in equal time quantization in Coulomb gauge) to one in which gluons split into two sets which may have different masses. If the theory is $SU(N)\times SU(M)$ with gluons in both groups having identical couplings (as suggested by Grand Unification arguments at large scales) it is immediate to see that different masses are generated for each subgroup. This global symmetry is not broken, but the split masses erase accidental symmetries that might be present due to the two couplings being the same at the large scale, such as $SU(N\times M)$ or similar. We also numerically explore a couple of low-dimensional examples of simple Lie groups, but in spite of the system having a form that would seem to allow spontaneous symmetry breaking, it is not triggered for these groups whose algebra has no ideal, and the dispersion relations for the various gluons converge to the same form.

    hep-phCommun.Theor.Phys.(2025)·0 citations
11. 11*

    Exploring Anisotropic flow via the Boltzmann Transport Equation Employing the Tsallis Blast Wave Description at LHC energies

    Aviral Akhil🇮🇳 · Swatantra Kumar Tiwari🇮🇳

    Anisotropic flows $i.e.$ azimuthal anisotropies in particle production are one of the important probes in characterizing the properties of the strongly interacting matter created in the relativistic heavy-ion collisions. These observables are sensitive to both the transport properties as well as the equation of state (EOS) of Quantum Chromodynamics (QCD) matter. We have adopted the Boltzmann transport equation (BTE) in the relaxation time approximation (RTA) to describe the experimental data for harmonic flows such as elliptic flow ($v_2$), triangular flow ($v_3$), quadrangular flow ($v_4$) obtained in heavy-ion collisions at Large Hadron Collider (LHC) energies. In this analysis, we have used Tsallis statistics as an initial distribution and the Tsallis Blast wave (TBW) description is used as the equilibrium distribution function while describing the evolution of the particle production in BTE. We have fitted the transverse momentum spectra, $v_2$, $v_3$, and $v_4$ of identified hadrons such as pion, kaon, and proton for Pb-Pb and Xe-Xe collisions at the LHC energies of $\sqrt{s_{NN}}$ = 5.02 TeV and $\sqrt{s_{NN}}$ = 5.44 TeV, respectively for various centralities. Our study offers a comparative analysis between the two distinct collision systems operating at comparable collision energies. The present formulation successfully fits the experimental data for $p_T$-spectra upto $p_T$ = 8 GeV and effectively explains the anisotropic flows data upto $p_T$ = 10 GeV with a very favourable ${\chi }^2/ndf$. We observe that the average transverse flow velocity ($<{\beta }_r>$) and the kinetic freeze-out temperature ($T$) extracted in our analysis decrease as we go towards the peripheral collisions. The azimuthal modulation amplitudes (${\rho }_a$) exhibit an increasing pattern as one moves from central to peripheral collisions in both the Pb-Pb and Xe-Xe nuclei interactions.

    hep-phnucl-thJ.Phys.G(2024)·12 citations
12. 12*

    A consistent resummation of mass and soft logarithms in processes with heavy flavours

    Andrea Ghira🇮🇹 · Simone Marzani🇮🇹 · Giovanni Ridolfi🇮🇹

    Perturbative calculations for processes that involve heavy flavours can be performed in two approaches: the massive scheme and the massless one. The former enables one to fully account for the heavy-quark kinematics, while the latter allows one to resum potentially-large mass logarithms. Furthermore, the two schemes can be combined to take advantage of the virtues of each of them. Both massive and massless calculations can be supplemented by soft-gluon resummation. However matching between massive and massless resummed calculations is difficult, essentially because of the non-commutativity of the soft and massless limits. In this paper, we develop a formalism to combine resummed massless and massive calculations. We obtain an all-order expression that consistently resums both mass and soft logarithms to next-to-leading logarithmic accuracy. We perform detailed calculations for the decay of the Higgs into a heavy-quark pair and discuss the applications of this formalism to different processes.

    hep-phJHEP(2023)·26 citations
13. 13*

    $D_{(s)}-$ mesons semileptonic form factors in the 4-flavor holographic QCD

    Hiwa A. Ahmed🇨🇳 · Yidian Chen🇨🇳 · Mei Huang🇨🇳

    We investigate semileptonic form factors of $D_{(s)}$ meson from a modified soft-wall 4-flavor holographic model. The model successfully reproduces the masses and decay constants of various mesons, including $\rho$, $K^{\ast }$, $D^{\ast }$, $D_s^{\ast }$, $a_1$, $K_1$, $f_1$, $D_1$,$D_{s1}$, $\pi$, $K$, $\eta$, $D$, and $D_s$. Moreover, we study the semileptonic decay processes $D^{+}\to (\pi ,K,\eta )l^{+}{\nu }_l$ and $D_s^{+}\to (K,\eta )l^{+}{\nu }_l$, associated with the vector meson exchange, as well as $D_{(s)}^{+}\to K^{}{l}^{+}{\nu }_l$, associated with the vector and axial vector meson exchange. The form factors $f_{+}(q^2)$ for $D\to \pi$ and $D_{(s)}\to K$ decays agree excellently with experimental and lattice data, outperforming other theoretical approaches. The $f_{+}(q^2)$ form factor for $D^{+}\to \eta$ is compatible with experimental data, while a slight discrepancy is observed for $D_s^{+}\to \eta$ at large $q^2$. Additionally, we predict the vector form factors $V(q^2)$ and $A_1(q^2)$ for $D\to K^{}$ and $D_s\to K^{}$ decays, respectively. The results agree well with other approaches and lattice data at maximum recoil ($q^2=0$).

    hep-phPRD(2024)·15 citations
14. 14*

    Quantum algorithms for the simulation of perturbative QCD processes

    Herschel A. Chawdhry🇬🇧 · Mathieu Pellen🇩🇪

    Quantum computers are expected to give major speed-ups for the simulation of quantum systems. In these conference proceedings, we discuss quantum algorithms for the simulation of perturbative Quantum Chromodynamics (QCD) processes. In particular, we describe quantum circuits for simulating the colour part of the interactions of quarks and gluons. We implement our circuits on a simulated noiseless quantum computer and validate them by calculating colour factors for various examples of Feynman diagrams.

    hep-phhep-thquant-phPoS(2023)·2 citations
15. 15*

    Assumption Breakdown in Radiative Energy Loss

    Coleridge Faraday🇿🇦 · W. A. Horowitz🇿🇦

    We show that an integral assumption in DGLV radiative energy loss - the large formation time assumption - is violated at high-$p_T$ for phenomenologically relevant parameters. We further investigate the phenomenological impact of placing a new kinematic bound on the radiated gluon transverse momentum, which ensures that there are no contributions to the energy loss from regions of parameter space that violate the large formation time assumption. We find that this places a large sensitivity on the exact kinematic cutoff used, similar to the known collinear cutoff sensitivity, indicating the theoretical need for a rederivation of DGLV radiative energy with the large formation time assumption relaxed in order to make rigorous predictions. We additionally find that this large formation time cutoff dramatically reduces the size of a short pathlength correction to the DGLV radiative energy loss, which is of phenomenological interest in predicting suppression in small $p+A$ systems. We compute the phenomenological predictions utilizing this large formation time cutoff in both $p+A$ and $A+A$ collisions at the LHC, in a convolved radiative and elastic energy loss model.

    hep-phnucl-th6 citations
16. 16*

    Scale dependence of non-factorizable virtual corrections to Higgs boson production in weak boson fusion

    Christian Brønnum-Hansen🇩🇪 · Ming-Ming Long🇩🇪 · Kirill Melnikov🇩🇪

    The renormalization-scale dependence of the non-factorizable virtual corrections to Higgs boson production in weak boson fusion at next-to-next-to-leading order in perturbative QCD is unusually strong, due to the peculiar nature of these corrections. To address this problem, we compute the three-loop non-factorizable contribution to this process which accounts for the running of the strong coupling constant, and show that it stabilizes the theoretical prediction.

    hep-phJHEP(2023)·5 citations
17. 17*

    Interplay between the muon $g-2$ anomaly and the PTA nHZ gravitational waves from domain walls in next-to minimal supersymmetric standard model

    Ming Xia Huang🇨🇳 · Fei Wang🇨🇳 · Ying Kai Zhang🇨🇳

    With some explicitly $Z_3$ breaking terms in the NMSSM effective superpotential and scalar potential, domain walls (DWs) from spontaneously breaking of the discrete symmetry in approximate $Z_3$-invariant NMSSM can collapse and lead to observable stochastic gravitational wave (GW) background signals. In the presence of a hidden sector, such terms may originate from the geometric superconformal breaking with holomorphic quadratic correction to frame function when the global scale-invariant superpotential is naturally embedded into the canonical superconformal supergravity models. The smallness of such mass parameters in the NMSSM may be traced back to the original superconformal invariance. Naive estimations indicate that a SUSY explanation to muon $g-2$ anomaly can have tension with the constraints on SUSY by PTA data, because large SUSY contributions to $\Delta a_{\mu }$ in general needs relatively light superpartners while present ${\Omega }_{gw}^0$ can set the lower bounds for $m_{soft}$. We calculate numerically the signatures of GW produced from the collapse of DWs and find that the observed nHZ stochastic GW background by NANOGrav, etc., can indeed be explained with proper tiny values of $\chi m_{3/2}\sim 10^{-14}\mathrm{eV}$ for $\chi S^2$ case (and $\chi m_{3/2}\sim 10^{-10}\mathrm{eV}$ for $\chi H_u{H}_d$ case), respectively. Besides, there are still some parameter points, whose GW spectra intersect with the NANOGrav signal region, that can explain the muon $g-2$ anomaly to $1\sigma$ range.

    hep-phPRD(2024)·14 citations
18. 18*

    Bose-Einstein condensation and muon production in ultra-high energy cosmic ray particle collisions

    V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺

    Collisions of cosmic ray particles with ultra-high initial energies with nuclei in the atmosphere open a wide room for appearing of the novel dynamical features for multiparticle production processes. In particular, the pion-lasing behavior driven by Bose-Einstein condensation would result in the shift to larger multiplicities and, as consequence, could provide, in general, the enhanced yield of cosmic muons. In the present work the critical value of the space charged particle density for onset of Bose-Einstein condensation of the boson (pion) wave-packets into the same wave-packet state is estimated within the model with complete multiparticle symmetrization for the energy domain corresponded to the ultra-high energy cosmic rays (UHECR). Energy dependence of mean density of charged pions is evaluated for the cases of absent of the Bose-Einstein effects and for presence of laser-like behavior of pions. The possible influence of the Bose-Einstein condensation is discussed for the muon production in UHECR particle collisions with the atmosphere.

    hep-phastro-ph.HEPhys.Atom.Nucl.(2024)·3 citations
19. 19*

    Searching for sbottom LSP at the LHC

    Paulina Knees🇦🇷 · Essodjolo Kpatcha🇪🇸 · Iñaki Lara🇵🇱 · Daniel E. López-Fogliani🇦🇷 · Carlos Muñoz🇪🇸

    Assuming that the sbottom is the lightest supersymmetric particle (LSP), we carry out an analysis of the relevant signals expected at the LHC. The discussion is established in the framework of the $\mu \nu$SSM, where the presence of $R$-parity violating couplings involving right-handed neutrinos solves simultaneously the $\mu$-problem and the accommodation of neutrino masses and mixing angles. The sbottoms are pair produced at the LHC, decaying to a lepton and a top quark or a neutrino and a bottom quark. The decays can be prompt or displaced, depending on the regions of the parameter space of the model. We focus the analysis on the right sbottom LSP, since the left sbottom is typically heavier than the left stop because of the D-term contribution. We compare the predictions of this scenario with ATLAS and CMS searches for prompt and long-lived particles. To analyze the parameter space we sample the $\mu \nu$SSM for a right sbottom LSP, paying special attention to reproduce the current experimental data on neutrino and Higgs physics, as well as flavor observables. For displaced (prompt) decays, our results translate into lower limits on the mass of the right sbottom LSP of about $1041$ GeV ($1070$ GeV). The largest possible value found for the decay length is about $3.5$ mm.

    hep-phEPJC(2024)·4 citations
20. 20*

    Neutrino mass models at $\mu$TRISTAN

    P. S. Bhupal Dev🇺🇸 · Julian Heeck🇺🇸 · Anil Thapa🇺🇸

    We study the prospects of probing neutrino mass models at the newly proposed antimuon collider $\mu$TRISTAN, involving ${\mu }^{+}{e}^{-}$ scattering at $\sqrt{s}=346$ GeV and ${\mu }^{+}{\mu }^{+}$ scattering at $\sqrt{s}=2$ TeV. We show that $\mu$TRISTAN is uniquely sensitive to leptophilic neutral and doubly-charged scalars naturally occurring in various neutrino mass models, such as Zee, Zee-Babu, cocktail, and type-II seesaw models, over a wide range of mass and coupling values, well beyond the current experimental constraints. It also allows for the possibility to correlate the collider signals with neutrino mixing parameters and charged lepton flavor violating observables.

    hep-phhep-exEPJC(2024)·31 citations
21. 21*

    New bounds on light millicharged particles from the tip of the red-giant branch

    Audrey Fung🇨🇦 · Saniya Heeba🇨🇦 · Qinrui Liu🇨🇦 · Varun Muralidharan🇨🇦 · Katelin Schutz🇨🇦 · Aaron C. Vincent🇨🇦

    Stellar energy loss is a sensitive probe of light, weakly coupled dark sectors, including ones containing millicharged particles (MCPs). The emission of MCPs can affect stellar evolution, and therefore can alter the observed properties of stellar populations. In this work, we improve upon the accuracy of existing stellar limits on MCPs by self-consistently modelling (1) the MCP emission rate, accounting for all relevant in-medium effects and production channels, and (2) the evolution of stellar interiors (including backreactions from MCP emission) using the MESA stellar evolution code. We find MCP emission leads to significant brightening of the tip of the red-giant branch. Based on photometric observations of 15 globular clusters whose bolometric magnitudes are inferred using parallaxes from Gaia astrometry, we obtain robust bounds on the existence of MCPs with masses below 100 keV.

    hep-phastro-ph.GAastro-ph.SRPRD(2024)·36 citations
22. 22*

    Flows for Flows: Morphing one Dataset into another with Maximum Likelihood Estimation

    Tobias Golling🇨🇭 · Samuel Klein🇨🇭 · Radha Mastandrea🇺🇸 · Benjamin Nachman🇺🇸 · John Andrew Raine🇨🇭

    Many components of data analysis in high energy physics and beyond require morphing one dataset into another. This is commonly solved via reweighting, but there are many advantages of preserving weights and shifting the data points instead. Normalizing flows are machine learning models with impressive precision on a variety of particle physics tasks. Naively, normalizing flows cannot be used for morphing because they require knowledge of the probability density of the starting dataset. In most cases in particle physics, we can generate more examples, but we do not know densities explicitly. We propose a protocol called flows for flows for training normalizing flows to morph one dataset into another even if the underlying probability density of neither dataset is known explicitly. This enables a morphing strategy trained with maximum likelihood estimation, a setup that has been shown to be highly effective in related tasks. We study variations on this protocol to explore how far the data points are moved to statistically match the two datasets. Furthermore, we show how to condition the learned flows on particular features in order to create a morphing function for every value of the conditioning feature. For illustration, we demonstrate flows for flows for toy examples as well as a collider physics example involving dijet events

    hep-phcs.LGhep-exphysics.data-anPRD(2023)·14 citations
23. 23*

    Axion Paradigm with Color-Mediated Neutrino Masses

    A. Batra🇵🇹 · H.B. Câmara🇵🇹 · F.R. Joaquim🇵🇹 · R. Srivastava🇮🇳 · J.W.F. Valle🇪🇸

    We propose a generalized Kim-Shifman-Vainshtein-Zakharov-type axion framework in which colored fermions and scalars act as two-loop Majorana neutrino-mass mediators. The global Peccei-Quinn symmetry under which exotic fermions are charged solves the strong CP problem. Within our general proposal, various setups can be distinguished by probing the axion-to-photon coupling at helioscopes and haloscopes. We also comment on axion dark-matter production in the early Universe.

    hep-phPRL(2024)·9 citations
24. 24*

    How Effective is $N_{eff}$ at Discovering Dark Radiation in a Cosmology with Heavy Particle Decay?

    Katarina Bleau🇨🇦 · Joseph Bramante🇨🇦 · Christopher Cappiello🇨🇦

    Any light relic which was in thermal equilibrium with the Standard Model before it freezes out results in a shift in the effective number of neutrino species, $N_{eff}$. This quantity is being measured with increasing precision, and planned experiments would seemingly rule out light particles beyond the Standard Model, even for rather high temperature light particle freeze out. Here we explore how these bounds are loosened if the energy density of the light particles is diluted with respect to that of Standard Model radiation, which can happen if a heavy particle decays into the Standard Model bath after the light particle freezes out. After calculating how heavy state decays alter $N_{eff}$ for light particles beyond the Standard Model, we focus in particular on the case that the heavy decaying particle is a gravitino, and use current bounds on $N_{eff}$ to place constraints on the gravitino mass and the branching ratio into light particles for different values of the reheating temperature of the Universe.

    hep-phastro-ph.COhep-thJCAP(2024)·8 citations
25. 25*

    Sequestered String Models imply Split Supersymmetry

    Michele Cicoli🇮🇹 · Alessandro Cotellucci🇩🇪 · Hajime Otsuka🇯🇵

    Sequestering is a promising mechanism in 4D string models to reconcile high-scale inflation with low-energy supersymmetry. In this scenario the MSSM lives on branes at singularities and it is sequestered from the sources of supersymmetry breaking in the bulk. The soft-terms are suppressed with respect to the gravitino mass so that all moduli are heavy enough to avoid any cosmological moduli problem. In this paper we study stability bounds and flavour constraints on sequestered string models, finding that they can be satisfied if the soft-terms give rise to a mass spectrum typical of split supersymmetry with TeV-scale gauginos and sfermions around $10^7$ GeV. When instead scalar and gaugino masses are of the same order of magnitude, large flavour changing neutral currents can be avoided only by pushing the soft-terms above $10^6$ GeV. However this scenario is in tension with stability bounds due to the presence of charge and colour breaking vacua which could be populated in the early universe, and the possible emergence of directions along which the potential is unbounded from below.

    ↳ hep-thhep-phJHEP(2024)·3 citations
26. 26*

    Exploring Short-Range Correlations in Symmetric Nuclei: Insights into Contacts and Entanglement Entropy

    Wei Kou🇨🇳 · Jingxuan Chen🇨🇳 · Xurong Chen

    The Short-Range Correlations between nucleons in nuclei is regarded as a complex system. We investigate the relationship between the orbital entanglement entropy of SRCs $S_{ij}$ in nuclear structures and Tan contact $c_{ij}$, and find that the orbital entanglement entropies and Tan contacts corresponding to proton-proton SRC pairs and neutron-proton SRC pairs in nuclei demonstrate a scaling relation. More specifically, the proportionality of entanglement entropy between proton-proton pairs and neutron-proton pairs is directly related to the ratio of nuclear contacts within the atomic nucleus, demonstrating an approximate ratio of 2.0. Our research suggests that this scaling relationship should hold true for all symmetric nuclei, furthermore, we offer a possible explanation for this phenomenon.

    ↳ nucl-thhep-phPLB(2024)·7 citations
27. 27*

    Application of the path optimization method to a discrete spin system

    Kouji Kashiwa🇯🇵 · Yusuke Namekawa🇯🇵 · Akira Ohnishi🇯🇵 · Hayato Takase

    The path optimization method, which is proposed to control the sign problem in quantum field theories with continuous degrees of freedom by machine learning, is applied to a spin model with discrete degrees of freedom. The path optimization method is applied by replacing the spins with dynamical variables via the Hubbard-Stratonovich transformation, and the sum with the integral. The one-dimensional (Lenz-)Ising model with a complex coupling constant is used as a laboratory for the sign problem in the spin model. The average phase factor is enhanced by the path optimization method, indicating that the method can weaken the sign problem. Our result reproduces the analytic values with controlled statistical errors.

    ↳ hep-latcond-mat.stat-mechhep-phPRD(2023)·4 citations
28. 28*

    Neutrinos and Heavy Element Nucleosynthesis

    Xilu Wang🇨🇳 · Rebecca Surman🇺🇸

    This chapter discusses three nucleosynthesis processes involved in producing heavy nuclei beyond the iron group that are influenced or shaped by neutrino interactions: the v process, the vp process and the r process. These processes are all related to explosive events involving compact objects, such as core-collapse supernovae and binary neutron star mergers, where an abundant amount of neutrinos are emitted. The interactions of the neutrinos with nucleons and nuclei through both charged-current and neutral-current reactions play a crucial role in the nucleosynthesis processes. During the propagation of neutrinos inside the nucleosynthesis sites, neutrinos may undergo flavor oscillations that can also potentially affect the nucleosynthesis yields. Here we provide a general overview of the possible effects of neutrinos and neutrino flavor conversions on these three heavy-element nucleosynthesis processes.

    ↳ astro-ph.HEhep-phnucl-thIn: Tanihata, I., Toki, H., Kajino, T. (e…·8 citations
29. 29*

    Phenomenological footprints of Lambda varying gravity theories inspired from quantum gravity models in the multi-messenger era

    Michael R.R. Good🇰🇿 · Vasilios Zarikas🇬🇷

    An interesting phenomenological consequence of Lambda varying gravity theories inspired by quantum gravity models is reported. The treatment in the present work is quite general and applicable to several different actions with Lambda varying, especially those used in RG approaches to quantum gravity. An effective gravitational action with a scale varying cosmological constant, Lambda, which depends on the system's characteristics, like the length and the energy density, is the key feature. If the system is an astrophysical object, like a cluster of galaxies, a black hole, etc, non-negligible corrections arise to several observable quantities. Distinctive footprints could refer to luminosity distance and strong/weak lensing measurements, among others. The present study focuses on the SNIa luminosity distance observable.

    ↳ gr-qcastro-ph.COhep-phhep-thClass.Quant.Grav.(2023)·2 citations
30. 30*

    Early time dynamics far from equilibrium via holography

    Matthias Kaminski🇺🇸 · Casey Cartwright🇺🇸 · Marco Knipfer🇺🇸 · Michael F. Wondrak🇳🇱 · Björn Schenke🇺🇸 · Marcus Bleicher🇩🇪

    We investigate the early time dynamics of heavy ion collisions studying the time evolution of the energy-momentum tensor as well as energy-momentum correlations within a uniformly thermalizing holographic QGP. From these quantities, we suggest a far-from equilibrium definition of shear viscosity, which is a crucial property of QCD matter as it significantly determines the generation of elliptic flow already at early times. During an exemplary initial heating phase of the holographic QGP the shear viscosity of entropy density ratio decreases down to 60%, followed by an overshoot to 110% of the near-equilibrium value, $\eta /s=1/(4\pi )$. Implications for the QCD QGP are discussed. Subsequently, we consider a holographic QGP which is Bjorken-expanding. Its energy-momentum tensor components have a known hydrodynamic attractor to which all time evolutions collapse independent of the initial conditions. Based on this, we propose a definition for a far from equilibrium speed of sound, and analytically compute its hydrodynamic attractor. Subjecting this Bjorken-expanding plasma to an external magnetic field and an axial chemical potential, we study the chiral magnetic effect far from equilibrium.

    ↳ nucl-thhep-lathep-phhep-th+1PoS(2024)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.