Thu·Sep 30, 2021Thursday·September 30, 2021

1. 01*

   Strong isospin breaking in Sp(4) gauge theory

   Axel Maas🇦🇹 · Fabian Zierler🇦🇹

   A hidden strongly-interacting sector is a possible candidate for dark matter. One scenario consistent with astrophysical constraints is a QCD-like theory with gauge group Sp(4) and two fundamental non-degenerate fermions. We report exploratory investigations of the light spectrum and decay constants for this theory using lattice calculations.

   hep-lathep-phPoS(2022)·25 citations
2. 02*

   Double parton distributions in the nucleon from lattice simulations

   Christian Zimmermann🇩🇪

   We provide a first study of Mellin moments of double parton distributions (DPDs) in the nucleon on the lattice, where we consider several combinations of quark flavors and polarizations. These are accessible through two-current correlations, which can be obtained by evaluating four-point functions. In this context we consider all possible Wick contractions, where for almost all of them sufficiently clear signals are obtained. In the present study, we employ an $n_f=2+1$ CLS ensemble on a $96\times 32^3$ lattice with lattice spacing $a=0.0856\mathrm{fm}$ and the pseudoscalar masses $m_{\pi }=355\mathrm{MeV}$ and $m_K=441\mathrm{MeV}$.

   hep-latPoS(2022)·1 citation
3. 03*

   Stout-smearing, gradient flow and $c_{\text{SW}}$ at one loop order

   Maximilian Ammer🇩🇪 · Stephan Durr🇩🇪

   The one-loop determination of the coefficient $c_{\text{SW}}$ of the Wilson quark action has been useful to push the leading cut-off effects for on-shell quantities to $\mathcal{O}({\alpha }^{2}a)$ and, in conjunction with non-perturbative determinations of $c_{\text{SW}}$, to $\mathcal{O}(a^2)$, as long as no link-smearing is employed. These days it is common practice to include some overall link-smearing into the definition of the fermion action. Unfortunately, in this situation only the tree-level value $c_{\text{SW}}^{(0)}=1$ is known, and cut-off effects start at $\mathcal{O}(\alpha a)$. We present some general techniques for calculating one loop quantities in lattice perturbation theory which continue to be useful for smeared-link fermion actions. Specifically, we discuss the application to the 1-loop improvement coefficient $c_{\text{SW}}^{(1)}$ for overall stout-smeared Wilson fermions.

   hep-latPoS(2022)·2 citations
4. 04*

   A proposal for the Yang-Mills vacuum and mass gap

   Dimitrios Metaxas🇬🇷

   I examine a set of Feynman rules, and the resulting effective action, that were proposed in order to incorporate the constraint of Gauss's law in the perturbation expansion of gauge field theories. A set of solutions for the Lagrangian and Hamiltonian equations of motion in Minkowski space-time, as well as their stability, are investigated. A discussion of the Euclidean action, confinement, and the strong-CP problem is also included. The properties and symmetries of the perturbative and the confining vacuum are explored, as well as the possible transitions between them, and the relations with phenomenological models of the strong interactions.

   ↳ hep-thhep-lathep-phmath-ph+1EPJC(2022)·3 citations
5. 05*

   Metal-insulator transition in (2+1)-dimensional Hubbard model with tensor renormalization group

   Shinichiro Akiyama🇯🇵 · Yoshinobu Kuramashi🇯🇵 · Takumi Yamashita🇯🇵

   We investigate the doping-driven metal-insulator transition of the (2+1)-dimensional Hubbard model in the path-integral formalism with the tensor renormalization group method. We calculate the electron density $⟨n⟩$ as a function of the chemical potential $\mu$ choosing three values of the Coulomb potential with $U=80$, $8$, and $2$ as representative cases of the strong, intermediate, and weak couplings. We have determined the critical chemical potential at each $U$, where the Hubbard model undergoes the metal-insulator transition from the half-filling plateau with $⟨n⟩=1$ to the metallic state with $⟨n⟩>1$. Our results indicate that the model exhibits the metal-insulator transition over the vast region of the finite coupling $U$.

   ↳ cond-mat.str-elhep-latPTEP·20 citations
6. 06*

   Phase transitions between confinement and higgs phases in $\mathcal{N}=1SU(N_c)$ SQCD with $1\le N_F\le N_c-1$ quark flavors

   Victor L. Chernyak🇷🇺

   Considered is 4-dimensional $\mathcal{N}=1$ supersymmetric $SU(N_c)$ QCD (SQCD) with $1\le N_F\le N_c-1$ equal mass quark flavors in the fundamental representation. The gauge invariant order parameter $\rho$ is introduced distinguishing confinement (with $\rho =0$) and higgs (with $\rho \ne 0$) phases. Using a number of independent arguments for different variants of transition between the confinement and higgs regimes, it is shown that transitions between these regimes are not crossovers but the phase transitions. Besides, it is argued that these phase transitions are of the first order. This is opposite to the conclusion of the paper of E. Fradkin and S.H. Shenker [10] that the transition between the confinement and higgs regimes is the crossover, not the phase transition. And although the theories considered in this paper and in [10] are different, an experience shows that there is a widely spread opinion that the conclusion of [10] is applicable to all QCD-like theories: both lattice and continuum, both not supersymmetric and supersymmetric. This opinion is in contradiction with the results of this paper.

   ↳ hep-thhep-lathep-ph4 citations
7. 07*

   $N_C$ evolution of the light meson resonances

   Zhi-Hui Guo🇨🇳

   The variation of the resonance poles, i.e., the mass and width, originating from changing the values of $N_C$, the number of the QCD colors, provide an intuitive theoretical method to discriminate the interior constituents of hadrons. Many different approaches, including unitarized chiral amplitudes, dispersive methods, quark models, linear-sigma-model-like framework, etc., have been widely used to determine the $N_C$ trajectories of the various resonance pole positions. We focus on the discussions of the light-flavor meson resonances in this work.

   ↳ hep-phhep-latEur.Phys.J.ST(2021)·3 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.