Thu·Sep 9, 2021Thursday·September 9, 2021

1. 01*

   On $SU(2{)}_{CS}$-like groups and invariance of the fermionic action in QCD

   Marco Catillo🇨🇭

   In this work, we introduce some new $U(1)$ symmetry groups of the free fermionic action in euclidean space-time, which are a consequence of parity and time-reversal symmetries. Afterwards, we discuss how the introduction of a gauge interaction affects the invariance of the action, with special reference to QCD. Moreover, inspired by recent QCD lattice results of \textit{Glozman et al.}, in which an interesting and unexpected symmetry group has been observed, namely $SU(2{)}_{CS}$ (that contains $U(1{)}_A$ as subgroup), we build other $SU(2{)}_{CS}$-like groups in euclidean space-time using the previous introduced $U(1)$ groups. Finally we argue about the possible invariance of the fermionic action with respect these new $SU(2{)}_{CS}$-like groups and its consequence on the hadron temporal correlators.

   hep-latInt.J.Mod.Phys.A(2022)·4 citations
2. 02*

   Spontaneous symmetry breaking via inhomogeneities and the differential surface tension

   Gergely Endrődi🇩🇪 · Tamás György Kovács🇭🇺 · Gergely Markó🇩🇪

   We discuss spontaneously broken quantum field theories with a continuous symmetry group via the constraint effective potential. Employing lattice simulations with constrained values of the order parameter, we demonstrate explicitly that the path integral is dominated by inhomogeneous field configurations and that these are unambiguously related to the flatness of the effective potential in the broken phase. We determine characteristic features of these inhomogeneities, including their topology and the scaling of the associated excess energy with their size. Concerning the latter we introduce the differential surface tension -- the generalization of the concept of a surface tension pertaining to discrete symmetries. Within our approach, spontaneous symmetry breaking is captured merely via the existence of inhomogeneities, i.e. without the inclusion of an explicit breaking parameter and a careful double limiting procedure to define the order parameter. While here we consider the three-dimensional $O(2)$ model, we also elaborate on possible implications of our findings for the chiral limit of QCD.

   hep-latcond-mat.stat-mechhep-phhep-thPRL(2021)·11 citations
3. 03*

   Gluon EMC effects in nuclear matter

   Xuan-Gong Wang🇦🇺 · Wolfgang Bentz🇯🇵 · Ian C. Cloët🇺🇸 · Anthony W. Thomas🇦🇺

   We investigate the gluonic structure of nuclei within a mean-field model of nuclear structure based upon the modification of the structure of a bound nucleon, with the nucleon described by the Nambu--Jona-Lasinio model. This approach has been shown to reproduce the European Muon Collaboration (EMC) effect, involving the ratio of the spin-independent structure functions of a heavier nucleus to that of the deuteron. It also predicts a significant nuclear modification for the spin structure functions, known as the polarized EMC effect. Here we report sizeable nuclear modifications of the gluon distributions (a "gluon EMC effect") for the ratios of both the unpolarized and polarized gluon distributions in nuclear matter to those of a free nucleon.

   ↳ hep-phhep-exhep-latnucl-thJ.Phys.G(2022)·11 citations
4. 04*

   Discrete Gravity

   Ali H. Chamseddine🇱🇧 · Viatcheslav Mukhanov🇩🇪

   We assume that the points in volumes smaller than an elementary volume (which may have a Planck size) are indistinguishable in any physical experiment. This naturally leads to a picture of a discrete space with a finite number of degrees of freedom per elementary volume. In such discrete spaces, each elementary cell is completely characterized by displacement operators connecting a cell to the neighboring cells and by the spin connection. We define the torsion and curvature of the discrete spaces and show that in the limiting case of vanishing elementary volume the standard results for the continuous curved differentiable manifolds are completely reproduced.

   ↳ hep-thgr-qchep-latJHEP(2021)·6 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.