Thu·Dec 8, 2022Thursday·December 8, 2022

1. 01*

   Monopoles, spectra of overlap fermions, and eta-prime meson in external magnetic fields

   Masayasu Hasegawa🇷🇺

   The effects of external magnetic fields on monopoles, spectra of the overlap Dirac operator, instantons, and the mass of the eta-prime meson are examined by conducting lattice QCD simulations. The uniform external magnetic fields are applied to gauge field configurations with $N_f$ = 2 + 1 flavor quarks. The bare quark masses are tuned in order to obtain the physical values of the pion mass and of the ratio $\frac{m_s}{m_{u,d}}$. Standard configurations and configurations with applied external magnetic fields are generated in the color confinement and deconfinement phases. The intensity of external magnetic fields varies from $e|B|$ = 0.57 to 1.14 [GeV${}^2$]. To examine the influence of external magnetic fields on monopoles, we first calculate the monopole density, measure the lengths of the monopole loops and compare them with the absolute value of the Polyakov loops. Next, using the generated configurations, we compute the eigenvalues and eigenvectors of the overlap Dirac operator, which preserves exact chiral symmetry. To investigate how external magnetic fields affect the spectra of the overlap Dirac operator, we compute spectral densities, compare fluctuations of the eigenvalues of the overlap Dirac operator with the predictions of random matrix theory, and estimate the number of instantons and anti-instantons from the topological charges. In addition, we analyze smearing effects on these observables and chiral symmetry breaking. Finally, we calculate the decay constant of the pseudoscalar meson, the chiral condensate, and the square mass of the eta-prime meson using the eigenvalues and eigenvectors. We then extrapolate the numerical results in the chiral limit and demonstrate the effects of external magnetic fields on the extrapolation results. This article presents preliminary results.

   hep-latnucl-exnucl-thTheor.Math.Phys.(2024)·0 citations
2. 02*

   QCD topology with electromagnetic fields and the axion-photon coupling

   Bastian Brandt🇩🇪 · Francesca Cuteri🇩🇪 · Gergely Endrődi🇩🇪 · José Javier Hernández Hernández🇩🇪 · Gergely Markó🇩🇪

   The introduction of non-orthogonal electric and magnetic fields in the QCD vacuum enhances the weight of topological sectors with a nonzero topological charge. For weak fields, there is a linear response for the expectation value of the topological charge. We study this linear response and relate it to the QCD correction to the axion-photon coupling. We also analyse the magnetic field dependence of the topological susceptibility for a range of temperatures around $T_c$. In this work we use lattice simulations with improved staggered quarks at physical masses, including background magnetic and (imaginary) electric fields.

   hep-lathep-phPoS(2023)·10 citations
3. 03*

   The chiral phase transition at non-zero imaginary baryon chemical potential for different numbers of quark flavours

   Alfredo D'Ambrosio🇩🇪 · Owe Philipsen🇩🇪 · Reinhold Kaiser🇩🇪

   The so-called Columbia plot summarises the order of the QCD thermal transition as a function of the number of quark flavours and their masses. Recently, it was demonstrated that the first-order chiral transition region, as seen for $N_f\in [3,6]$ on coarse lattices, exhibits tricritical scaling while extrapolating to zero on sufficiently fine lattices. Here we extend these studies to imaginary baryon chemical potential. A similar shrinking of the first-order region is observed with decreasing lattice spacing, which again appears compatible with a tricritical extrapolation to zero.

   hep-latPoS(2023)·10 citations
4. 04*

   Holography on the lattice: the string worldsheet perspective

   Gabriel Bliard🇩🇪 · Ilaria Costa🇩🇪 · Valentina Forini🇬🇧

   We review the study, on the lattice, of the Green-Schwarz gauge-fixed string action describing worldsheet fluctuations about the minimal surface holographically dual to the null cusp Wilson loop, useful to evaluate the cusp anomaly of N = 4 super Yang-Mills (sYM). We comment on discretization, numerical explorations and challenges for the non-perturbative study of this benchmark model of gauge-fixed worldsheet actions.

   hep-lathep-thEur.Phys.J.ST(2023)·10 citations
5. 05*

   Thermodynamics of the Glueball Resonance Gas

   Enrico Trotti🇵🇱 · Shahriyar Jafarzade🇵🇱 · Francesco Giacosa🇵🇱

   We study the thermodynamic properties -- pressure, entropy and trace anomaly -- of a gas of glueballs that includes the glueball states obtained by various lattice simulations. We show that this model, called Glueball Resonance Gas (GRG) approach, describes well the thermal properties of the Yang-Mills sector of QCD below the critical temperature $T_c$, provided that $T_c$ is properly matched to the corresponding determination of the glueball masses, obtaining $T_c\sim 320\pm 20$ MeV. The inclusion into the GRG of heavier glueballs not yet seen on the lattice, assuming that glueballs follow Regge trajectories as quark-antiquark states do, leads only to a small correction. We consider the contribution to the pressure of the interactions between scalar-scalar and tensor-tensor glueballs, which turn out to be also negligible.

   ↳ hep-phhep-lathep-thEPJC(2023)·15 citations
6. 06*

   CDT and Horava-Lifshitz QG in Two Dimensions

   Yuki Sato🇯🇵

   The two-dimensional causal dynamical triangulations ($2$d CDT) is a lattice model of quantum geometry. In $2$d CDT, one can deal with the quantum effects analytically and explore the physics through the continuum limit. The continuum theory is known to be two-dimensional projectable Horava-Lifshitz quantum gravity ($2$d projectable HL QG). In this chapter, we wish to review the very relation between $2$d CDT and $2$d projectable HL QG in detail.

   ↳ hep-thgr-qchep-latIn: Bambi, C., Modesto, L., Shapiro, I. (…·2 citations
7. 07*

   Indirect new physics effects on ${\sigma }_{\mathrm{had}}$ confront the $(g-2{)}_{\mu }$ window discrepancies and the CMD-3 result

   Luc Darmé🇫🇷 · Giovanni Grilli di Cortona🇮🇹 · Enrico Nardi🇮🇹

   Recent lattice determinations of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment $a_{\mu }^{\mathrm{HVP}}$ have confirmed the discrepancy with the data-driven dispersive method. In the meanwhile the CMD-3 collaboration has reported a result for the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ cross section considerably larger than previous experimental results (and close to the lattice determinations) exacerbating the discordance between different $e^{+}{e}^{-}$ datasets. We explore to what extent these disagreements can be accounted for by some new physics effect altering selectively the individual experimental determinations of $\sigma (e^{+}{e}^{-}\to$hadrons). We find that specific effects of GeV-scale new particles are able to shift upwards the KLOE and BaBar results in the low and intermediate energy windows, while leaving unaffected the CMD-3 energy scan. Although these new physics effects cannot fully explain all the discrepancies among the different $\sigma (e^{+}{e}^{-}\to$hadrons) datasets, they succeed in mitigating the overall tension between data-driven and lattice estimates of $a_{\mu }^{\mathrm{HVP}}$. Remarkably, the additional loop corrections involving the new particles concur to solve the residual discrepancy with the experimental value of $(g-2{)}_{\mu }$.

   ↳ hep-phhep-exhep-latPRD(2023)·16 citations
8. 08*

   Abelian combinatorial gauge symmetry

   Hongji Yu🇨🇳 · Dmitry Green🇺🇸 · Andrei E. Ruckenstein · Claudio Chamon🇺🇸

   Combinatorial gauge symmetry is a principle that allows us to construct lattice gauge theories with two key and distinguishing properties: a) only one- and two-body interactions are needed; and b) the symmetry is exact rather than emergent in an effective or perturbative limit. The ground state exhibits topological order for a range of parameters. This paper is a generalization of the construction to any finite Abelian group. In addition to the general mathematical construction, we present a physical implementation in superconducting wire arrays, which offers a route to the experimental realization of lattice gauge theories with static Hamiltonians.

   ↳ cond-mat.str-elhep-latSciPost Phys.Core(2024)·7 citations
9. 09*

   New UTfit Analysis of the Unitarity Triangle in the Cabibbo-Kobayashi-Maskawa scheme

   UTfit Collaboration: Marcella Bona🇬🇧 · Marco Ciuchini🇮🇹 · Denis Derkach🇷🇺 · Fabio Ferrari🇮🇹 · Enrico Franco🇮🇹 · Vittorio Lubicz🇮🇹 · Guido Martinelli🇮🇹 · Davide Morgante🇮🇹 · Maurizio Pierini🇨🇭 · Luca Silvestrini🇮🇹 · Silvano Simula🇮🇹 · Achille Stocchi🇫🇷 and 4 other authors

   Flavour mixing and CP violation as measured in weak decays and mixing of neutral mesons are a fundamental tool to test the Standard Model (SM) and to search for new physics. New analyses performed at the LHC experiment open an unprecedented insight into the Cabibbo-Kobayashi-Maskawa (CKM) metrology and new evidence for rare decays. Important progress has also been achieved in theoretical calculations of several hadronic quantities with a remarkable reduction of the uncertainties. This improvement is essential since previous studies of the Unitarity Triangle did show that possible contributions from new physics, if any, must be tiny and could easily be hidden by theoretical and experimental errors. Thanks to the experimental and theoretical advances, the CKM picture provides very precise SM predictions through global analyses. We present here the results of the latest global SM analysis performed by the UTfit collaboration including all the most updated inputs from experiments, lattice QCD and phenomenological calculations.

   ↳ hep-phhep-exhep-latRend.Lincei Sci.Fis.Nat.(2023)·170 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.