Thu·Dec 22, 2022Thursday·December 22, 2022

1. 01*

   Two- and three-particle scattering in the (1+1)-dimensional O(3) non-linear sigma model

   Jorge Baeza-Ballesteros🇪🇸 · Maxwell T. Hansen🇬🇧

   We study two- and three-particle scattering in the O(3) non-linear sigma model in 1+1 dimensions, focusing on the isospin-1 and isospin-2 channels for two particles, and the isospin-3 channel for three. We perform numerical simulations for four values of the physical volume, each at three lattice spacings, using a three-cluster generalization of the cluster update algorithm, and directly extrapolate the determined finite-volume energies to the continuum at fixed physical volume. Lattice results for two particles are then compared against exact predictions, obtained by combining analytic results for the scattering phase shifts and the (1+1)-dimensional two-particle formalism that relates these to finite-volume energies. Analogous comparisons in the three-particle sector are underway, making use of the three-particle relativistic-field-theory finite-volume formalism.

   hep-latPoS(2023)·4 citations
2. 02*

   Tuning of QCD+QED simulations with C${}^{\star }$ boundary conditions

   Anian Altherr🇨🇭 · Lucius Bushnaq🇮🇪 · Isabel Campos🇪🇸 · Marco Catillo🇨🇭 · Alessandro Cotellucci🇩🇪 · Madeleine Dale🇩🇪 · Patrick Fritzsch🇮🇪 · Roman Gruber🇨🇭 · Jens Lücke🇩🇪 · Marina Marinkovic🇪🇸 · Agostino Patella🇩🇪 · Nazario Tantalo🇮🇹 · Paola Tavella🇨🇭

   We give an update on the ongoing effort of the RC${}^{\star }$ collaboration to generate fully dynamical QCD+QED ensembles with C${}^{\star }$ boundary conditions using the openQ${}^{\star }$D code. The simulations were tuned to the U-symmetric point ($m_d=m_s$) with pions at $m_{{\pi }^{\pm }}\approx 400$ MeV. The splitting of the light mesons is used as one of three tuning observables and fixed to $m_{K^0}-m_{K^{\pm }}\approx 5$ MeV and $m_{K^0}-m_{K^{\pm }}\approx 25$ MeV on ensembles with renormalized electromagnetic coupling ${\alpha }_{\text{R}}\approx {\alpha }_{\text{phys}}$ and ${\alpha }_R\approx 5.5{\alpha }_{phys}$ respectively. The tuning of the three independent quark masses to the desired lines of constant physics is particularly challenging. We will define the chosen hadronic renormalization scheme, and we will present a tuning strategy based on a combination of mass reweighting and linear interpolation to explore the parameter space. We will comment on finite-volume effects comparing meson masses on two different volumes with $m_{{\pi }^{\pm }}L\approx 3.2$ and $m_{{\pi }^{\pm }}L\approx 5.1$. We will also provide some technical details on our updated strategy to calculate the sign of the fermionic Pfaffian, which arises in presence of C${}^{\star }$ boundary conditions in place of the standard fermionic determinant. More technical details on the generation of the configurations can be found in J. Lücke's proceedings

   hep-latPoS(2023)·6 citations
3. 03*

   Heavy quark diffusion coefficient with gradient flow

   Viljami Leino🇩🇪 · Nora Brambilla🇩🇪 · Julian Mayer-Steudte🇩🇪 · Peter Petreczky🇺🇸

   The heavy quark diffusion coefficient is encoded in the spectral functions of the chromo-electric and the chromo-magnetic correlators, of which the latter describes the T/M contribution. We study these correlators at two different temperatures $T=1.5T_c$ and $T=10^4{T}_c$ in the deconfined phase of SU(3) gauge theory. We use gradient flow for noise reduction. We perform both continuum and zero flow time limits to extract the heavy quark diffusion coefficient. Our results imply that the mass suppressed effects in the heavy quark diffusion coefficient are 20% for bottom quarks and 34% for charm quark at $T=1.5T_c$.

   hep-lathep-phPoS(2023)·3 citations
4. 04*

   Towards precision charm physics with a mixed action

   Alessandro Conigli🇪🇸 · Julien Frison🇩🇪 · Gregorio Herdoíza🇪🇸 · Carlos Pena🇪🇸 · Alejandro Sáez🇪🇸 · Javier Ugarrio🇪🇸

   We report on our first set of results for charm physics, using a mixed-action setup with maximally twisted valence fermions on CLS $N_f=2+1$ ensembles. This setup avoids the need of improvement coefficients to subtract $O(a{m}_c)$ effects. The charm quark mass, $D$ and $D_s$ decay constants are computed on a subset of CLS ensembles, which allows to take the continuum limit and extrapolate to the physical pion mass, and assess the scaling properties. Special attention is paid to the implementation of techniques to deal with systematic uncertainties. Our results show excellent prospects for high-precision computations on the full set of ensembles.

   hep-latPoS(2023)·2 citations
5. 05*

   Benchmark Continuum Limit Results for Spectroscopy with Stabilized Wilson Fermions

   Francesca Cuteri🇩🇪 · Anthony Francis🇹🇼 · Patrick Fritzsch🇮🇪 · Giovanni Pederiva🇩🇪 · Antonio Rago🇩🇰 · Andrea Shindler🇺🇸 · Andre Walker-Loud🇺🇸 · Savvas Zafeiropoulos🇫🇷

   The OpenLat initiative presents its results of lattice QCD simulations using Stabilized Wilson Fermions (SWF) using 2+1 quark flavors. Focusing on the $\mathrm{SU}(3)$ flavor symmetric point $m_{\pi }=m_K=412$ MeV, four different lattice spacings ($a=0.064,0.077,0.094,0.12$ fm) are used to perform the continuum limit to study cutoff effects. We present results on light hadron masses; for the determination we use a Bayesian analysis framework with constraints and model averaging to minimize the bias in the analysis.

   hep-latPoS(2023)·7 citations
6. 06*

   On improvement of the axial-vector current with stabilised Wilson fermions

   Patrick Fritzsch🇮🇪 · Jochen Heitger🇩🇪 · Justus T. Kuhlmann🇩🇪

   We report on the determination of the improvement coefficient $c_{\mathrm{A}}$ for the non-singlet axial-vector current $A_{\mu }^a(x)$ in the framework of stabilised Wilson-Clover fermions within three flavour lattice QCD. This is done by requiring the PCAC relation to hold for two different pseudo-scalar states. To generate these states, wavefunctions altering spatial structures on the boundaries of a Schrödinger functional lattice are employed and some variations of the (previously applied) wavefunction method are explored. The improvement coefficient is determined on a few ensembles for a range of gauge couplings that is potentially useful for future applications. Preliminary results on the renormalisation constants $Z_{\mathrm{V}}$ for the vector current and $Z_{\mathrm{A}}$ for the axial-vector current are also presented.

   hep-latPoS(2023)·2 citations
7. 07*

   Charm fluctuations in (2+1)-flavor QCD at high temperature

   Sipaz Sharma🇩🇪

   Using the high statistics datasets of the HotQCD Collaboration, generated with the HISQ (2+1)-flavor action for light and strange quarks, and treating the charm sector in the quenched approximation, we analyze the second and fourth order cumulants of charm fluctuations and the correlations of charm with lighter conserved flavor quantum numbers. We can make use of a factor 100 larger statistics on $N_{\tau }=8$ lattices which never have been used in studies of charm fluctuations. Analyzing correlations of charm fluctuations with baryon number and electric charge fluctuations we can project onto charmed baryon and meson correlations and compare results with quark model extended hadron resonance gas model calculations. We aim at a precise determination of the dissociation temperature of charmed hadrons and will probe the sensitivity of the fluctuations observables to the presence of multiple-charmed baryons.

   hep-latPoS(2023)·7 citations
8. 08*

   Direct access to hadronic decay parameters with twisted boundary conditions

   Benoît Blossier🇫🇷 · Jochen Heitger🇩🇪 · Jan Neuendorf🇫🇷 · Teseo San José🇫🇷

   Our exploratory study looks for direct access to the resonant hadronic transition amplitude without resorting to the Lüscher formalism. We study the decay $\Psi (3770)\to \bar{D}D$ by applying partially twisted boundary conditions to the quenched charm quark, circumventing possible problems with final state interactions. If successful, we could compute the dependence of the transition amplitude on the charm-quark mass and test the predictions made by phenomenological quark-pair-creation models. Finally, we study if and to what extent an extraction of the excited state $\Psi (3770)$ is necessary for this analysis.

   hep-lathep-phPoS(2023)·1 citation
9. 09*

   Numerical Stochastic Perturbation Theory around instantons

   Paolo Baglioni🇮🇹 · Francesco Di Renzo🇮🇹

   Numerical Stochastic Perturbation Theory (NSPT) has over the years proved to be a valuable tool, in particular being able to reach unprecedented orders for Lattice Gauge Theories, whose perturbative expansions are notoriously cumbersome. One of the key features of the method is the possibility to expand around non-trivial vacua. While this idea has been around for a while, and it has been implemented in the case of the (non-trivial) background of the Schrödinger functional, NSPT expansions around instantons have not yet been fully worked out. Here we present computations for the double well potential in quantum mechanics. We compute a few orders of the expansion of the ground-state energy splitting in the one-instanton sector. We discuss how (already) known two-loop results are reproduced and present the current status of higher-order computations.

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

    Unobservability of topological charge in nonabelian gauge theory

    Nodoka Yamanaka🇯🇵

    We show that the topological charge of nonabelian gauge theory is unphysical by using the fact that it always involves the unphysical gauge field component proportional to the gradient of the gauge function. The removal of Gribov copies, which may break the Becchi-Rouet-Stora-Tyutin symmetry, is irrelevant thanks to the perturbative one-loop finiteness of the chiral anomaly. The unobservability of the topological charge immediately leads to the resolution of the Strong CP problem. We also present important consequences such as the physical relevance of axial $U(1)$ symmetry, the $\theta$-independence of vacuum energy, the unphysicalness of topological instantons, and the impossibilities of realizing the sphaleron induced baryogenesis as well as the chiral magnetic effect. The unphysical vacuum angle and the axial $U(1)$ symmetry also imply that the CP phase of the Cabibbo-Kobayashi-Maskawa matrix is the sole source of CP violation of the standard model.

    ↳ hep-thhep-lathep-phnucl-th17 citations
11. 11*

    50 Years of Quantum Chromodynamics

    Franz Gross🇺🇸 · Eberhard Klempt🇩🇪 · Stanley J. Brodsky🇺🇸 · Andrzej J. Buras🇩🇪 · Volker D. Burkert🇺🇸 · Gudrun Heinrich🇩🇪 · Karl Jakobs🇩🇪 · Curtis A. Meyer🇺🇸 · Kostas Orginos🇺🇸 · Michael Strickland🇺🇸 · Johanna Stachel🇩🇪 · Giulia Zanderighi🇩🇪 and 83 other authors

    This paper presents a comprehensive review of both the theory and experimental successes of Quantum Chromodynamics, starting with its emergence as a well defined theory in 1972-73 and following developments and results up to the present day. Topics include a review of the earliest theoretical and experimental foundations; the fundamental constants of QCD; an introductory discussion of lattice QCD, the only known method for obtaining exact predictions from QCD; methods for approximating QCD, with special focus on effective field theories; QCD under extreme conditions; measurements and predictions of meson and baryon states; a special discussion of the structure of the nucleon; techniques for study of QCD at high energy, including treatment of jets and showers; measurements at colliders; weak decays and quark mixing; and a section on the future, which discusses new experimental facilities or upgrades currently funded. The paper is intended to provide a broad background for Ph.D. students and postdocs starting their career. Some contributions include personal accounts of how the ideas or experiments were developed.

    ↳ hep-phhep-exhep-lathep-thEPJC(2023)·416 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.