Mon·Jan 22, 2024Monday·January 22, 2024

1. 01*

   Event-Generator Validation with MCPLOTS and LHC@home

   Natalia Korneeva🇷🇺 · Anton Karneyeu🇷🇺 · Peter Skands🇦🇺

   We document several recent updates to the MCPLOTS event-generator validation resource. The project is based on the RIVET analysis library and harnesses volunteer computing provided by LHC@home to generate high-statistics MC comparisons to data. Users interact with the resource via a simple website, mcplots.cern.ch, which provides flexible options for requesting comparison plots and comprehensive statistical analyses on demand, all in a few clicks. The project has been structured to enable community-driven developments, and we discuss the computational back end, the web front end, and how to add new data analyses, generators, and tunes that would be accessible on the website for comparison.

   hep-phEur.Phys.J.Plus(2024)·5 citations
2. 02*

   Unraveling collisional energy loss of a heavy quark in quark-gluon plasma

   Jiazhen Peng🇨🇳 · Kewei Yu🇨🇳 · Shuang Li🇨🇳 · Wei Xiong🇨🇳 · Fei Sun🇨🇳 · Wei Xie🇨🇳

   At leading order in QCD coupling constant, we compute the energy loss per traveling distance of a heavy quark $dE/dz$ from elastic scattering off thermal quarks and gluons at a temperature $T$, including the thermal perturbative description of soft scatterings ($-t<-t^{\ast }$) and a perturbative QCD-based calculation for hard collisions ($-t>-t^{\ast }$). Within this soft-hard factorization model, we find that the full results of $dE/dz$ behaves a mild sensitivity to the intermediate cutoff $t^{\ast }$, supporting the validity of the soft-hard approach within the temperature region of interest. We re-derive the analytic formula for $dE/dz$ in the high-energy approximation, $E_1\gg m_1^2/T$, where $E_1$ is the injected heavy quark energy and $m_1$ is its mass. It is realized that the soft logarithmic contribution, $dE/dz\propto ln(-t^{\ast }/m_D^2)$, arises from the $t$-channel scattering off thermal partons, while the hard logarithmic term, $dE/dz\propto ln[E_{1}T/(-t^{\ast })]$, stems from the $t$-channel scattering off thermal partons, and the one $dE/dz\propto ln(E_{1}T/m_1^2)$ comes from the $s$- and $u$-channel scattering off gluons. The sum of these contributions cancels the $t^{\ast }$-dependence as observed in the full result. The mass hierarchy is observed $dE/dz(charm)>dE/dz(bottom)$. Our full results are crucial for a better description of heavy quark transport in QCD medium, in particular at low and moderate energy. We also calculate the energy loss by imposing the Einstein's relationship. The related results appear to be systematically larger than that without imposing the Einstein's relationship.

   hep-phnucl-thPRD(2024)·11 citations
3. 03*

   Four top final states with NLO accuracy in perturbative QCD: 4 lepton channel

   Nikolaos Dimitrakopoulos🇩🇪 · Malgorzata Worek🇩🇪

   Triggered by the observation of four top-quark production at the LHC by the ATLAS and CMS collaboration we report on the calculation of the next-to-leading order QCD corrections to the Standard Model process $pp\to t\bar{t}t\bar{t}$ in the $4\ell$ top-quark decay channel. We take into account higher-order QCD effects in both the production and decays of the four top quarks. The latter effects are treated in the narrow width approximation, which preserves top-quark spin correlations throughout the calculation. We present results for two selected renormalisation and factorisation scale settings and three different PDF sets. Furthermore, we study the main theoretical uncertainties that are associated with the neglected higher-order terms in the perturbative expansion and with the parameterisation of the PDF sets. The results at the integrated and differential fiducial cross-section level are shown for the LHC Run III center-of-mass energy of $\sqrt{s}=13.6$ TeV. Our findings are particularly relevant for precise measurements of the four top-quark fiducial cross sections and for the modelling of top-quark decays at the LHC.

   hep-phhep-exJHEP(2024)·12 citations
4. 04*

   Implications of the Weak Gravity Conjecture on Charge, Kinetic Mixing, the Photon Mass, and More

   Fayez Abu-Ajamieh🇮🇳 · Nobuchika Okada🇺🇸 · Sudhir K Vempati🇮🇳

   We investigate several phenomenological implications of the Weak Gravity Conjecture (WGC). We find that the WGC implies that the SM neutrinos must be electrically neutral, that the electric charge in the SM must be quantized, and that the photon must be massless. In addition, we use the WGC to set lower bounds on the electric charge of milli-charged particles (mCP), the gauge coupling of several $U(1)$ extensions of the SM, their kinetic mixing parameter with the SM $U(1{)}_{\text{EM}}$, and the axion couplings to photons and fermions. We also set an upper bound on the lifetime of the proton.

   hep-phgr-qchep-thNPB(2025)·8 citations
5. 05*

   Higgs production at RHIC and the positivity of the gluon helicity distribution

   Daniel de Florian🇦🇷 · Stefano Forte🇮🇹 · Werner Vogelsang🇩🇪

   We show that the negative polarized gluon distribution $\Delta g$ found in a recent global next-to-leading order QCD analysis of the nucleon helicity structure is incompatible with the fundamental requirement that physical cross-sections must not be negative. Specifically, we show that the fact that this polarized gluon strongly violates the positivity condition $|\Delta g|\le g$ in terms of the unpolarized gluon distribution $g$ leads to negative cross-sections for Higgs boson production at RHIC as a physical process, implying that this negative $\Delta g$ is unphysical.

   hep-phPRD(2024)·16 citations
6. 06*

   An Effective Cosmological Collider

   Nathaniel Craig🇺🇸 · Soubhik Kumar🇺🇸 · Amara McCune🇺🇸

   Effective field theories (EFTs) of heavy particles coupled to the inflaton are rife with operator redundancies, frequently obscured by sensitivity to both boundary terms and field redefinitions. We initiate a systematic study of these redundancies by establishing a minimal operator basis for an archetypal example, the abelian gauge-Higgs-inflaton EFT. Working up to dimension 9, we show that certain low-dimensional operators are entirely redundant and identify new non-redundant operators with potentially interesting cosmological collider signals. Our methods generalize straightforwardly to other EFTs of heavy particles coupled to the inflaton.

   hep-phastro-ph.COhep-thJHEP(2024)·26 citations
7. 07*

   Probing New Physics at Cosmic Dawn with 21-cm Cosmology

   Omer Zvi Katz🇮🇱 · Nadav Outmezguine🇺🇸 · Diego Redigolo🇮🇹 · Tomer Volansky🇮🇱

   21-cm cosmology provides an exciting opportunity to probe new physics dynamics in the early universe. In particular, a tiny sub-component of dark matter that interacts strongly with the visible sector may cool the gas in the intergalactic medium and significantly alter the expected absorption signal at Cosmic Dawn. However, the information about new physics in this observable is obscured by astrophysical systematic uncertainties. In the absence of a microscopic framework describing the astrophysical sources, these uncertainties can be encoded in a bottom up effective theory for the 21-cm observables in terms of unconstrained astrophysical fluxes. In this paper, we take a first step towards a careful assessment of the degeneracies between new physics effects and the uncertainties in these fluxes. We show that the latter can be constrained by combining measurements of the UV luminosity function, the Planck measurement of the CMB optical depth to reionization, and an upper bound on the unresolved X-ray flux. Leveraging those constraints, we demonstrate how new physics signatures can be disentangled from astrophysical effects. Focusing on the case of millicharged dark matter, we find sharp predictions, with small uncertainties within the viable parameter space.

   hep-phastro-ph.CONPB(2024)·10 citations
8. 08*

   Axion emission from strange matter in core-collapse SNe

   Mael Cavan-Piton🇫🇷 · Diego Guadagnoli🇫🇷 · Micaela Oertel🇫🇷 · Hyeonseok Seong🇩🇪 · Ludovico Vittorio🇫🇷

   The duration of the neutrino burst from the supernova event SN 1987A is known to be sensitive to exotic sources of cooling, such as axions radiated from the dense and hot hadronic matter thought to constitute the inner core of the supernova. We perform the first quantitative study of the role of hadronic matter beyond the first generation -- in particular strange matter. We do so by consistently including the full baryon and meson octets, and computing axion emissivity induced from baryon-meson to baryon-axion scatterings as well as from baryon decays. We consider a range of supernova thermodynamic conditions, as well as equation-of-state models with different strangeness content. We obtain the first bound on the axial axion-strange-strange coupling, as well as the strongest existing bound on the axion-down-strange counterpart. Our bound on the latter coupling can be as small as $O(10^{-2})$ for $f_a=10^9$ GeV.

   hep-phastro-ph.HEPRL(2024)·31 citations
9. 09*

   Photoproduction of lepton pair in ultra-relativistic heavy-ion collisions

   Kewei Yu🇨🇳 · Jiazhen Peng🇨🇳 · Shuang Li🇨🇳 · Kejun Wu🇨🇳 · Wei Xie🇨🇳 · Fei Sun🇨🇳

   Dilepton production provides a unique probe of the strong electromagnetic field produced in heavy-ion collisions. To map out the behavior of its transverse momentum broadening, we present a theoretical model based on the equivalent photon approximation, and then we update it to make direct comparisons with the recent experimental measurements. We find that the model calculations can describe well, not only the average transverse momentum squared of $e^{+}{e}^{-}$ pairs in Au--Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV, but also the acoplanarity of ${\mu }^{+}{\mu }^{-}$ pairs in Pb--Pb collisions at$\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Furthermore, the model predictions are also able to reproduce the measured dependencies of the pair mass and the transverse momentum squared.

   ↳ nucl-thhep-phPRC(2024)·3 citations
10. 10*

    The PTA Hellings and Downs Correlation Unmasked by Symmetries

    Alex Kehagias🇬🇷 · Antonio Riotto🇨🇭

    The Hellings and Downs correlation curve describes the correlation of the timing residuals from pairs of pulsars as a function of their angular separation on the sky and is a smoking-gun signature for the detection of an isotropic stochastic background of gravitational waves. We show that it can be easily obtained from realizing that Lorentz transformations are conformal transformations on the celestial sphere and from the conformal properties of the two-point correlation of the timing residuals. This result allows several generalizations, e.g. the calculation of the three-point correlator of the time residuals and the inclusion of additional polarization modes (vector and/or scalar) arising in alternative theories of gravity.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2024)·10 citations
11. 11*

    Entanglement distribution in Bhabha scattering with entangled spectator particle

    Massimo Blasone🇮🇹 · Gaetano Lambiase🇮🇹 · Bruno Micciola🇮🇹

    We analyze how entanglement is generated and distributed in a Bhabha scattering process $(e^{-}{e}^{+}\to e^{-}{e}^{+})$ at tree level. In our setup an electron $A$ scatters with a positron $B$, which is initially entangled with another electron $C$ (spectator), that does not participate directly to the process. We find that the QED scattering generates and distributes entanglement in a non-trivial way among the three particles: the correlations in the output channels $AB$, $AC$ and $BC$ are studied in detail as functions of the scattering parameters and of the initial entanglement weight. Although derived in a specific case, our results exhibit some general features of other similar QED scattering processes, for which the extension of the present analysis is straightforward.

    ↳ quant-phhep-phhep-thPRD(2024)·32 citations
12. 12*

    What can abelian gauge theories teach us about kinematic algebras?

    Kymani Armstrong-Williams🇬🇧 · Silvia Nagy🇬🇧 · Chris D. White🇬🇧 · Sam Wikeley🇸🇪

    The phenomenon of BCJ duality implies that gauge theories possess an abstract kinematic algebra, mirroring the non-abelian Lie algebra underlying the colour information. Although the nature of the kinematic algebra is known in certain cases, a full understanding is missing for arbitrary non-abelian gauge theories, such that one typically works outwards from well-known examples. In this paper, we pursue an orthogonal approach, and argue that simpler abelian gauge theories can be used as a testing ground for clarifying our understanding of kinematic algebras. We first describe how classes of abelian gauge fields are associated with well-defined subgroups of the diffeomorphism algebra. By considering certain special subgroups, we show that one may construct interacting theories, whose kinematic algebras are inherited from those already appearing in a related abelian theory. Known properties of (anti-)self-dual Yang-Mills theory arise in this way, but so do new generalisations, including self-dual electromagnetism coupled to scalar matter. Furthermore, a recently obtained non-abelian generalisation of the Navier-Stokes equation fits into a similar scheme, as does Chern-Simons theory. Our results provide useful input to further conceptual studies of kinematic algebras.

    ↳ hep-thgr-qchep-phJHEP(2024)·21 citations
13. 13*

    Diffraction and elastic scattering at the LHC

    Anna Fehérkuti

    Several LHC experiments exploit the high acceptance in the forward region. Most of them use the possibility of measuring the intact proton in an elastic event. This approach can enhance the purity of selecting jet-gap-jet events, leading to refined limits on photon-induced processes or to a better study of pion pair production. Diffraction and elastic scattering plays also the main role when measuring the rho-parameter or the nuclear slope in total cross-section measurements. In this talk a summary of the latest results on this topic from the ATLAS, CMS and LHCb experiments has been presented.

    ↳ hep-exhep-phPoS(2024)·0 citations
14. 14*

    Using Bayesian Inference to Distinguish Neutrino Flavor Conversion Scenarios via a Prospective Supernova Neutrino Signal

    Sajad Abbar🇩🇪 · Maria Cristina Volpe🇫🇷

    The upcoming galactic core-collapse supernova is expected to produce a considerable number of neutrino events within terrestrial detectors. By using Bayesian inference techniques, we address the feasibility of distinguishing among various neutrino flavor conversion scenarios in the supernova environment, using such a neutrino signal. In addition to the conventional MSW, we explore several more sophisticated flavor conversion scenarios, such as spectral swapping, fast flavor conversions, flavor equipartition caused by non-standard neutrino interactions, magnetically-induced flavor equilibration, and flavor equilibrium resulting from slow flavor conversions. Our analysis demonstrates that with a sufficiently large number of neutrino events during the supernova accretion phase (exceeding several hundreds), there exists a good probability of distinguishing among feasible neutrino flavor conversion scenarios in the supernova environment.

    ↳ astro-ph.HEhep-phnucl-thPRD(2025)·12 citations
15. 15*

    Constraints on prospective deviations from the cold dark matter model using a Gaussian Process

    Martiros Khurshudyan🇪🇸 · Emilio Elizalde🇪🇸

    Recently, using Bayesian Machine Learning, a deviation from the cold dark matter model on cosmological scales has been put forward. Such model might replace a proposed non-gravitational interaction between dark energy and dark matter, and help solve the $H_0$ tension problem. The idea behind the learning procedure relied there on a generated expansion rate, while the real expansion rate was just used to validate the learned results. In the present work, however, the emphasis is put on a Gaussian Process (GP) with the available $H(z)$ data confirming the possible existence of the already learned deviation. Three cosmological scenarios are considered: a simple one, with equation of state parameter for dark matter ${\omega }_{dm}={\omega }_0\ne 0$, and two other models, with corresponding parameters ${\omega }_{dm}={\omega }_0+{\omega }_{1}z$ and ${\omega }_{dm}={\omega }_0+{\omega }_{1}z/(1+z)$. The constraints obtained on the free parameters ${\omega }_0$ and ${\omega }_1$ hint towards a dynamical nature of the deviation. The dark energy dynamics is also reconstructed, revealing interesting aspects connected with the $H_0$ tension problem. It is concluded, however, that improved tools and more data are needed, in order to reach a better understanding of the reported deviation.

    ↳ gr-qcastro-ph.COhep-phhep-thGalaxies(2024)·9 citations
16. 16*

    Negative magnetoresistance induced by longitudinal photons in Dirac/Weyl semimetals

    J. L. Acosta Avalo🇨🇺 · H. Pérez Rojas

    A low-energy model is built to study systems such as Dirac/Weyl semimetals, according to statistical quantum electrodynamics formalism. We report that the introduction of a pseudoscalar, associated to longitudinal photons propagating along a magnetic field B, could transforms a Dirac semimetal into a Weyl semimetal with a pair of Weyl nodes for each point of Dirac. The nodes are separated by a pseudovector electric field induced dynamically along B associated to a chiral effect on the Fermi surface. A topological quantum transition is produced between a chiral-and non chiral symmetry phase. A general expression to the longitudinal magnetoconductivity is found. It provides the possibility of generalizing the usual expressions of the magnetoconductivity reported in the literature. This has a quadratic dependence on B, which is associated with a positive contribution to the magnetoconductivity. This is a prominent signature of the chiral magnetic effect in Dirac/Weyl systems in parallel electric and magnetic fields. We report a chiral effect induced by longitudinal photons associated to a negative longitudinal magnetoresistance in Dirac systems via an axial anomaly relation. We show some numerical results, and reproduced with a high level of accuracy some of the experimental results, in the low temperature region, obtained to the magnetoresistance of ZrTe5 and Na3Bi. We believe that a wide variety of these semimetals can be studied by using our general expression to the negative longitudinal magnetoresistance.

    ↳ cond-mat.mes-hallhep-ph0 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.