Tue·Dec 21, 2021Tuesday·December 21, 2021

1. 01*

   $K\pi$ scattering at physical pion mass using distillation

   Nelson Pitanga Lachini🇬🇧 · Peter Boyle🇬🇧 · Felix Erben🇬🇧 · Michael Marshall🇬🇧 · Antonin Portelli🇬🇧

   Scattering at physical pion mass is still an exploratory field in lattice QCD. This generally involves the extraction of excited states through multi-particle correlators on systems with resonances. In that context, distillation has been demonstrated to be effective both as a smearing kernel and a computational tool. Motivated by the study of the smearing profile of the distillation operator, we compare stochastic and exact distillation cases for different numbers of Laplacian eigenvectors using an RBC-UKQCD $N_f=2+1$ domain-wall fermion lattice with a physical pion mass.

   hep-latPoS(2022)·6 citations
2. 02*

   From tensors to qubits

   Yannick Meurice🇺🇸 · Alexei Bazavov🇺🇸 · Patrick Dreher🇺🇸 · Erik Gustafson🇺🇸 · Leon Hostetler🇺🇸 · Ryo Sakai🇺🇸 · Shan-Wen Tsai🇺🇸 · Judah Unmuth-Yockey🇺🇸 · Jin Zhang🇺🇸

   We discuss recent progress in Tensor Lattice Field Theory and economical, symmetry preserving, truncations suitable for quantum computations or simulations. We focus on spin and gauge models with continuous Abelian symmetries such as the Abelian Higgs model and emphasize noise-robust implementations of Gauss's law. We discuss recent progress concerning the comparison between field digitizations and character expansions, symmetry breaking in tensor language, wave-packet preparation and possible new implementations of Abelian models using Rydberg atoms.

   hep-latquant-phPoS(2022)·0 citations
3. 03*

   Particle density probability distribution function and center symmetry breaking in finite density lattice gauge theories

   Shinji Ejiri🇯🇵

   We study the nature of the phase transition at high temperature and high density in lattice gauge theories by focusing on the probability distribution function, which represents the probability that a certain density will be realized in a heat bath. The probability distribution function is obtained by constructing a canonical partition function by fixing the number of particles from the grand partition function. However, if the Z3 center symmetry, which is important for understanding the finite temperature phase transition of SU(3) lattice gauge theory, is maintained on a finite lattice, the probability distribution function is always zero, except when the number of particles is a multiple of 3. For U(1) gauge theory, this problem is more extreme. The probability distribution becomes zero when the particle number is not zero. In this study, we find a solution to this problem and propose a method of avoiding the sign problem, which is an important problem at finite density, using the center symmetry. This problem is essentially the same as the problem that the expectation value of the Polyakov loop is always zero when calculating with finite volume. In the case of U(1) lattice gauge theory with heavy fermions, numerical simulations are actually performed, and we demonstrate that the probability distribution function at a finite density can be calculated by the method proposed in this study.

   hep-latPoS(2022)·0 citations
4. 04*

   The chiral phase transition from strong to weak coupling

   Francesca Cuteri🇩🇪 · Alfredo D'Ambrosio🇩🇪 · Owe Philipsen🇩🇪 · Alessandro Sciarra🇩🇪

   The order of the chiral phase transition of lattice QCD with unimproved staggered fermions is known to depend on the number of quark flavours, their masses and the lattice spacing. Previous studies in the literature for $N_f\in \{3,4\}$ show first-order transitions, which weaken with decreasing lattice spacing. Here we investigate what happens when lattices are made coarser to establish contact to the strong coupling region. For $N_f\in \{4,8\}$ we find a drastic weakening of the transition when going from $N_{\tau }=4$ to $N_{\tau }=2$, which is consistent with a second-order chiral transition reported in the literature for $N_f=4$ in the strong coupling limit. This implies a non-monotonic behaviour of the critical quark or pseudo-scalar meson mass, which separates first-order transitions from crossover behaviour, as a function of lattice spacing.

   hep-latPoS(2022)·1 citation
5. 05*

   Backpropagating Hybrid Monte Carlo algorithm for fast Lefschetz thimble calculations

   Genki Fujisawa🇯🇵 · Jun Nishimura🇯🇵 · Katsuta Sakai🇯🇵 · Atis Yosprakob🇯🇵

   The Picard-Lefschetz theory has been attracting much attention as a tool to evaluate a multi-variable integral with a complex weight, which appears in various important problems in theoretical physics. The idea is to deform the integration contour based on Cauchy's theorem using the so-called gradient flow equation. In this paper, we propose a fast Hybrid Monte Carlo algorithm for evaluating the integral, where we "backpropagate" the force of the fictitious Hamilton dynamics on the deformed contour to that on the original contour, thereby reducing the required computational cost by a factor of the system size. Our algorithm can be readily extended to the case in which one integrates over the flow time in order to solve not only the sign problem but also the ergodicity problem that occurs when there are more than one thimbles contributing to the integral. This enables, in particular, efficient identification of all the dominant saddle points and the associated thimbles. We test our algorithm by calculating the real-time evolution of the wave function using the path integral formalism.

   hep-latcond-mat.stat-mechhep-thphysics.comp-phJHEP(2022)·22 citations
6. 06*

   Form factors for semileptonic $B\to \pi$, $B_s\to K$ and $B_s\to D_s$ decays

   Jonathan Flynn🇬🇧 · Ryan Hill🇬🇧 · Andreas Juettner🇬🇧 · Amarjit Soni🇺🇸 · J. Tobias Tsang🇩🇰 · Oliver Witzel🇩🇪

   We report on our determinations of $B\to \pi \ell \nu$, $B_s\to K\ell \nu$ and $B_s\to D_s\ell \nu$ semileptonic form factors. In addition we discuss the determination of $R$-ratios testing lepton-flavor universality and suggest an improved ratio. Our calculations are based on the set of 2+1 flavor domain-wall Iwasaki gauge field configurations generated by the RBC/UKQCD collaboration with three lattice spacings of $1/a=1.78$, $2.38$, and $2.79\text{GeV}$. We use the relativistic heavy quark action for $b$ quarks and charm quarks are simulated with the Möbius domain-wall fermion action.

   hep-latPoS(2022)·12 citations
7. 07*

   Nonperturbative running of the quark mass for $N_f=3$ QCD from the chirally rotated Schrödinger Functional

   Isabel Campos Plasencia🇪🇸 · Mattia Dalla Brida🇨🇭 · Giulia Maria de Divitiis🇮🇹 · Andrew Lytle🇺🇸 · Mauro Papinutto🇮🇹 · Ludovica Pirelli🇮🇹 · Anastassios Vladikas🇮🇹

   We study the Renormalisation Group (RG) running of the quark mass, for $N_f=3$ QCD with Wilson fermions in a mixed action setup, with standard Schrödinger Functional (SF) boundary conditions for sea quarks and chirally rotated Schrödinger Functional ($\chi$SF) boundary conditions for valence quarks. This necessitates the tuning of the boundary factor $z_f(g_0^2)$ of the $\chi$SF valence action, in order to ensure that QCD symmetries are fully recovered in the continuum. The properties of this novel setup are monitored through the ratios $Z_S/Z_P$ and ${\Sigma }_S/{\Sigma }_P$ of the renormalisation parameters and step scaling functions of the scalar and pseudoscalar densities. Where comparison is possible, our $Z_S/Z_P$ results are found to agree with previous determinations, based on a mass ratio method arXiv:1906.03445 and Ward identities arXiv:2005.01352, arXiv:2101.10969, with Schrödinger Functional boundary conditions. The behaviour of ${\Sigma }_S/{\Sigma }_P$ confirms the theoretical expectations of $\chi$SF QCD, related to the restoration of the theory's symmetries in the continuum limit. From the step scaling function of the pseudoscalar density we obtain the quark mass RG-running function from hadronic to perturbative energy scales. This is fully compatible with the earlier result obtained in a similar setup for Wilson quarks with Schrödinger Functional boundary conditions arXiv:1802.05243 and provides a strong universality test for the two lattice setups.

   hep-latPRD(2022)·4 citations
8. 08*

   Magnetic moments of the doubly charged axial-vector $T_{cc}^{++}$ states

   U. Ozdem🇹🇷

   Motivated by the discovery of the doubly-charmed state $T_{cc}^{+}$ and with the help of light-cone sum rules, the magnetic moments of possible $T_{cc}^{++}$ states are calculated. While calculating the magnetic moments of these states, these particles are considered in the molecular picture and they have $J^P=1^{+}$ quantum numbers. The magnetic moment results obtained for the $T_{cc}^{++}$ states are large due to the double electric charge. The results obtained in this study can be checked using other theoretical models. The magnetic moments of the hadrons reveal valuable knowledge about the size and the shape of the hadrons. Measurement of the magnetic moment of the $T_{cc}^{++}$ states in future experimental collaborations can be very useful to understanding substructure and identification the quantum numbers of these states.

   ↳ hep-phhep-exhep-latPRD(2022)·25 citations
9. 09*

   Study of the hidden charm $D{\bar{D}}^{\ast }$ interactions in chiral effective field theory

   Hao Xu🇨🇳

   We study the chiral interactions of the hidden charm $D{\bar{D}}^{\ast }$ system within chiral effective field theory. Chiral Lagrangians are constructed by incorporating the chiral symmetry, heavy quark symmetry as well as proper charge conjugation properties of the heavy mesons. The interacting potentials of the $S$-wave $D{\bar{D}}^{\ast }$ are calculated up to second chiral order at 1-loop level, where complete two-pion exchange interactions are included. We further investigate the behaviors of the potentials in coordinate space, as well as their bound state properties. Our studies indicate that there exists a interacting strength ordering among considered four channels: $\text{str.}[0^{+}(1^{++})]>\text{str.}[0^{-}(1^{+-})]>\text{str.}[1^{+}(1^{+-})]>\text{str.}[1^{-}(1^{++})]$ where str. stands for the strength of the $D{\bar{D}}^{\ast }$ interaction. Moreover, we find that $X(3872)$ can be treated as a good candidate of $0^{+}(1^{++})$ molecular state. There also tends to form $0^{-}(1^{+-})$ and $1^{+}(1^{+-})$ molecular states and we expect the experiments to search for the predicted multi-structures around the $D{\bar{D}}^{\ast }$ mass region.

   ↳ hep-phhep-latnucl-thPRD(2022)·8 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.