Mon·Oct 16, 2023Monday·October 16, 2023

1. 01*

   Heavy flavor as a probe of hot QCD matter produced in proton-proton collisions

   Jiaxing Zhao🇫🇷 · Joerg Aichelin🇫🇷 · Pol Bernard Gossiaux🇫🇷 · Klaus Werner🇫🇷

   The creation of a quark-gluon plasma (QGP) is expected in heavy ion collisions. It came as a surprise that proton-proton collisions at ultrarelativistic energies show as well a ``QGP-like'' behavior and signs of the creation of a fluid, although the corresponding system size is not more than a few cubic femtometers. Even more surprisingly, also heavy flavor particles seem to be part of the fluid or at least interact with it. In this paper, we will investigate in a quantitative way this ``collective behavior'' of heavy flavor, by employing the newly developed EPOS4HQ approach, which has proven to be compatible with basic experimental data of light flavor hadrons. We will investigate all observables, which may manifest collectivity, as particle spectra, elliptic flow, baryon-to-meson ratios, and two-particle correlations, and compare the results with experimental data. We will try to disentangle initial state effects, those being due to interactions between charm quarks and plasma partons, and final state effects (hadronization).

   hep-phnucl-thPRD(2024)·42 citations
2. 02*

   Probing axion-like particles at the Electron-Ion Collider

   Reuven Balkin🇮🇱 · Or Hen🇺🇸 · Wenliang Li🇺🇸 · Hongkai Liu🇮🇱 · Teng Ma🇮🇱 · Yotam Soreq🇮🇱 · Mike Williams🇺🇸

   The Electron-Ion Collider~(EIC), a forthcoming powerful high-luminosity facility, represents an exciting opportunity to explore new physics. In this article, we study the potential of the EIC to probe the coupling between axion-like particles~(ALPs) and photons in coherent scattering. The ALPs can be produced via photon fusion and decay back to two photons inside the EIC detector. In a prompt-decay search, we find that the EIC can set the most stringent bound for $m_a\lesssim 20\text{GeV}$ and probe the effective scales $\Lambda \lesssim 10^5$GeV. In a displaced-vertex search, which requires adopting an EM calorimeter technology that provides directionality, the EIC could probe ALPs with $m_a\lesssim 1\text{GeV}$ at effective scales $\Lambda \lesssim 10^7\text{GeV}$. Combining the two search strategies, the EIC can probe a significant portion of unexplored parameter space in the $0.2<m_a<20\text{GeV}$ mass range.

   hep-phhep-exJHEP(2024)·39 citations
3. 03*

   Interplay of inert doublet and vector-like lepton triplet with displaced vertices at the LHC/FCC and MATHUSLA

   Priyotosh Bandyopadhyay🇮🇳 · Mariana Frank🇨🇦 · Snehashis Parashar🇮🇳 · Chandrima Sen🇮🇳

   We study the interaction between the inert Higgs doublet (IDM) dark matter and a vector-like $SU(2)$ triplet lepton (VLL), both of which are $Z_2$-odd. The vector current of the VLL with the $Z$-boson rules out a fermionic or two-component dark matter scenario. However, a compressed mass spectrum and a sufficiently small Yukawa coupling allows co-annihilation and late decay of the VLL into the IDM sector, affecting the relic density of the pseudoscalar dark matter. The same two factors enable displaced decay of the VLL states, providing novel signatures involving hadronically quiet displaced multi-lepton final states. Such signatures to probe the model are studied at the 14 and 27 TeV LHC, as well as the 100 TeV FCC-hh. In addition to being detectable at the CMS/ATLAS experiments, if the new particles have sub-100 GeV masses, signals can also be seen at the proposed MATHUSLA detector.

   hep-phJHEP(2024)·11 citations
4. 04*

   Systematic Evaluation of Generative Machine Learning Capability to Simulate Distributions of Observables at the Large Hadron Collider

   Jan Gavranovič🇸🇮 · Borut Paul Kerševan🇸🇮

   Monte Carlo simulations are a crucial component when analysing the Standard Model and New physics processes at the Large Hadron Collider. This paper aims to explore the performance of generative models for complementing the statistics of classical Monte Carlo simulations in the final stage of data analysis by generating additional synthetic data that follows the same kinematic distributions for a limited set of analysis-specific observables to a high precision. Several deep generative models are adapted for this task and their performance is systematically evaluated using a well-known benchmark sample containing the Higgs boson production beyond the Standard Model and the corresponding irreducible background. The paper evaluates the autoregressive models and normalizing flows and the applicability of these models using different model configurations is investigated. The best performing model is chosen for a further evaluation using a set of statistical procedures and a simplified physics analysis. By implementing and performing a series of statistical tests and evaluations we show that a machine-learning-based generative procedure can be used to generate synthetic data that matches the original samples closely enough and that it can therefore be incorporated in the final stage of a physics analysis with some given systematic uncertainty.

   hep-phEPJC(2024)·5 citations
5. 05*

   Low-energy matrix elements of heavy-quark currents

   Harvey B. Meyer🇩🇪

   In QCD at energies well below a heavy-quark threshold, the heavy-quark vector current can be represented via local operators made of the lighter quarks and of the gluon fields. We extract the leading perturbative matching coefficients for the two most important sets of operators from known results. As an application, we analytically determine the $\mathrm{O}({\alpha }_s^3)m_c^2/m_b^2$ effect of the bottom quark current on the $R(s)$ ratio below the bottom but above the charm threshold. For the low-energy representation of the charm quark current, the two most important operators are given by the total divergence of dimension-six gluonic operators. We argue that the charm magnetic moment of the nucleon is effectively measuring the forward matrix elements of these gluonic operators and predict the corresponding bottom magnetic moment. Similarly, the contribution of the charm current to $R(s\approx 1{\mathrm{GeV}}^2)$, which is associated with quark-disconnected diagrams, is dominantly determined by the decay constants of the $\omega$ and $\varphi$ mesons with respect to the two gluonic operators.

   hep-phhep-latnucl-thEPJC(2023)·0 citations
6. 06*

   Testing Predictions of the Chiral Anomaly in Primakoff Reactions at COMPASS

   Dominik Ecker🇩🇪

   The chiral anomaly is a fundamental property of quantum chromodynamics (QCD). It governs the transition amplitudes for processes involving an odd number of Goldstone bosons of chiral symmetry breaking. In case of the coupling of three pions to a photon, the magnitude of the resulting coupling is $F_{3\pi }$ and the value is predicted by chiral perturbation theory with small uncertainty. It can experimentally be measured in ${\pi }^{-}\gamma \to {\pi }^{-}{\pi }^0$ scattering. Here, we report on a precision experiment on $F_{3\pi }$ using the COMPASS experiment at CERN where pion-photon scattering is mediated via the Primakoff effect using heavy nuclei as target. We exploit the interference of the production of the ${\pi }^{-}{\pi }^0$ final state via the chiral anomaly with the photo-production of the $\rho (770)$ resonance over a wide mass range ($M_{{\pi }^{-}{\pi }^0}<1\text{ GeV}/c^2$). This is in contrast to previous measurements restricting themselves to the threshold region ($M_{{\pi }^{-}{\pi }^0}<370\text{ MeV}$) only. Our analysis allows to simultaneously extract the radiative width of the $\rho (770)$ resonance and gives a stronger handle on $F_{3\pi }$ in a unified approach thereby minimizing systematic effects rarely addressed previously.

   hep-phNuovo Cim.C(2024)·7 citations
7. 07*

   Generalized Gluon Distribution for Quarkonium Dynamics in Strongly Coupled $\mathcal{N}=4$ Yang-Mills Theory

   Govert Nijs🇺🇸 · Bruno Scheihing-Hitschfeld🇺🇸 · Xiaojun Yao🇺🇸

   We study the generalized gluon distribution that governs the dynamics of quarkonium inside a non-Abelian thermal plasma characterizing its dissociation and recombination rates. This gluon distribution can be written in terms of a correlation function of two chromoelectric fields connected by an adjoint Wilson line. We formulate and calculate this object in $\mathcal{N}=4$ supersymmetric Yang-Mills theory at strong coupling using the AdS/CFT correspondence, allowing for a nonzero center-of-mass velocity $v$ of the heavy quark pair relative to the medium. The effect of a moving medium on the dynamics of the heavy quark pair is described by the simple substitution $T\to \sqrt{\gamma }T$ in agreement with previous calculations of other observables at strong coupling, where $T$ is the temperature of the plasma in its rest frame, and $\gamma =(1-v^2{)}^{-1/2}$ is the Lorentz boost factor. Such a velocity dependence can be important when the quarkonium momentum is larger than its mass. Contrary to general expectations for open quantum systems weakly coupled with large thermal environments, the contributions to the transition rates that are usually thought of as the leading ones in Markovian descriptions vanish in this strongly coupled plasma. This calls for new theoretical developments to assess the effects of strongly coupled non-Abelian plasmas on in-medium quarkonium dynamics. Finally, we compare our results with those from weakly coupled QCD, and find that the QCD result moves toward the $\mathcal{N}=4$ strongly coupled result as the coupling constant is increased within the regime of applicability of perturbation theory. This behavior makes it even more pressing to develop a non-Markovian description of quarkonium in-medium dynamics.

   hep-phhep-thnucl-thPRD(2024)·19 citations
8. 08*

   Interplay between Parton Distribution Functions and New Physics signals

   Elie Hammou🇬🇧

   The analysis and the interpretation of the LHC data require a precise determination of Parton Distribution Functions (PDFs) in order to detect reliably potential signs of new physics. I present a systematic study designed to assess the risk of absorbing, and thus missing, signals from heavy new physics in the PDFs parameterisation during the High-Luminosity LHC run. I discuss the consequences of such a PDF "contamination" and consider possible solutions to it, for example the inclusion of other experimental data probing large-x regions at low-energy.

   hep-ph0 citations
9. 09*

   Lattice computation of the Kugo-Ojima correlation function

   Nuno Miguel Rebelo Brito🇵🇹

   As of today, color confinement in Quantum Chromodynamics remains a mystery from the theoretical point of view. So far, no analytical proof of color confinement has been found and the mechanism that confines colored states from the space of physical states is still unknown. Taichiro Kugo and Izumi Ojima proposed such confinement mechanism, using as basis the BRST-symmetry and derived the requirements for the realization of this mechanism. One such requirement, which happens to be the non-trivial one, is that a special correlation function, the Kugo-Ojima correlation function $u(p^2)$, approaches $-1$ at the origin ($p^2=0)$. This correlation function can be obtained on the lattice within the lattice formulation of gauge theories. The present work consists on lattice results for this correlation function on the Landau gauge. We present results obtained from 4 symmetric large volume lattices $(32^4,48^4,64^4,80^4)$ with $\beta =6.0$ on the Landau gauge. A test on the transversality of the Kugo-Ojima correlation function is also performed, along with some statistical considerations of the results. The results present further evidence that the Kugo-Ojima confinement scenario is not realized on the lattice and that the Kugo-Ojima correlation function, in the Landau gauge, is transverse. Our findings align qualitatively with existing literature.

   ↳ hep-lathep-phnucl-th2 citations
10. 10*

    Can we explain cosmic birefringence without a new light field beyond Standard Model?

    Yuichiro Nakai🇨🇳 · Ryo Namba🇯🇵 · Ippei Obata🇩🇪 · Yu-Cheng Qiu🇨🇳 · Ryo Saito🇯🇵

    The recent analysis of the Planck 2018 polarization data shows a nonzero isotropic cosmic birefringence (ICB) that is not explained within the $\Lambda$CDM paradigm. We then explore the question of whether the nonzero ICB is interpreted by the framework of the Standard Model Effective Field Theory (SMEFT), or at the energy scales of the cosmic microwave background, the low-energy EFT (LEFT) whose dynamical degrees of freedom are five SM quarks and all neutral and charged leptons. Our systematic study reveals that any operator in the EFT on a cosmological background would not give the reported ICB angle, which is observationally consistent with frequency independence. In particular, we estimate the size of the ICB angle generated by the effect that the cosmic microwave background photons travel through the medium of the cosmic neutrino background with parity-violating neutrino-photon interactions and find that it would be too small to explain the data. If the reported ICB angle should be confirmed, then our result would indicate the existence of a new particle that is lighter than the electroweak scale and feebly interacting with the SM particles.

    ↳ astro-ph.COhep-phJHEP(2024)·23 citations
11. 11*

    Partial-wave analysis of ${\tau }^{-}\to {\pi }^{-}{\pi }^{-}{\pi }^{+}{\nu }_{\tau }$ at Belle

    Andrei Rabusov🇩🇪 · Daniel Greenwald🇩🇪 · Stephan Paul (for the Belle collaboration)🇩🇪

    We present preliminary results of a partial-wave analysis of ${\tau }^{-}\to {\pi }^{-}{\pi }^{-}{\pi }^{+}{\nu }_{\tau }$ in data from the Belle experiment at the KEKB ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ collider. We demonstrate the presence of the ${\mathrm{a}}_1(1420)$ and ${\mathrm{a}}_1(1640)$ resonances in tauon decays and measure their masses and widths. We also present validation of our findings using a model-independent approach. Our results can improve modeling in simulation studies necessary for measuring the tauon electric and magnetic dipole moments and Michel parameters.

    ↳ hep-exhep-phNuovo Cim.C(2024)·6 citations
12. 12*

    Perturbatively including inhomogeneities in axion inflation

    Valerie Domcke🇨🇭 · Yohei Ema🇺🇸 · Stefan Sandner🇪🇸

    Axion inflation, i.e. an axion-like inflaton coupled to an Abelian gauge field through a Chern-Simons interaction, comes with a rich and testable phenomenology. This is particularly true in the strong backreaction regime, where the gauge field production heavily impacts the axion dynamics. Lattice simulations have recently demonstrated the importance of accounting for inhomogeneities of the axion field in this regime. We propose a perturbative scheme to account for these inhomogeneities while maintaining high computational efficiency. Our goal is to accurately capture deviations from the homogeneous axion field approximation within the perturbative regime as well as self-consistently determine the onset of the non-perturbative regime.

    ↳ astro-ph.COhep-phJCAP(2024)·25 citations
13. 13*

    The Cornell black hole

    Euro Spallucci🇮🇹 · Anais Smailagic🇮🇹

    The Cornell potential can be derived from a recently proposed non-local extension of Abelian electrodynamics. Non-locality can be alternatively described by an extended charge distributions in Maxwell electrodynamics. We state that in these models the energy momentum tensor necessarily requires the presence of the interaction term between the field and the charge itself. We show that this extended form of energy momentum tensor leads to an exact solution of the Einstein equations describing a charged AdS black hole. We refer to it as the "Cornell black hole"(CBH). Identifying the effective cosmological constant with the pressure of Van der Waals fluid, we study the gas-liquid phase transition and determine the critical parameters.

    ↳ hep-thgr-qchep-phPLB(2023)·5 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.