Fri·Oct 29, 2021Friday·October 29, 2021

1. 01*

   Monopoles of the Dirac type and color confinement in QCD

   Tsuneo Suzuki🇯🇵 · Atsuki Hiraguchi🇹🇼 · Katsuya Ishiguro🇯🇵

   We present results of $SU(3)$ Monte-Carlo studies of a new color confinement scheme proposed recently due to Abelian-like monopoles of the Dirac type corresponding in the continuum limit to violation of the non-Abelian Bianchi identities (VNABI). The simulations are done without any additional gauge-fixing smoothing the vacuum. We get for the first time, in pure $SU(3)$ simulations with the standard Wilson action, (1) the perfect Abelian dominance with respect to the static potentials on $12^4\sim 16^4$ lattices at $\beta =5.6-5.8$ using the multilevel method. (2) The perfect monopole as well as Abelian dominances with respect to the static potentials by evaluating the Polyakov loop correlators on $24^3\times 4$ at $\beta =5.6$. The Abelian photon part gives zero string tension. (3) The Abelian dual Meissner effect is observed with respect to the Abelian gauge field and Abelian monopoles. The Abelian electric field of a color is squeezed due to the solenoidal monopole current with the corresponding color. Although the scaling and the volume dependence are not yet studied in $SU(3)$, the present results and the previous $SU(2)$ results are consistent with the new Abelian picture of color confinement that each one of eight (three in $SU(2)$) colored electric flux is squeezed by the corresponding colored Abelian-like monopole of the Dirac type corresponding to VNABI.

   hep-latPoS(2022)·0 citations
2. 02*

   QCD thermodynamics at non-zero isospin asymmetry

   Bastian B. Brandt🇩🇪 · Francesca Cuteri🇩🇪 · Gergely Endrodi🇩🇪

   We study the thermodynamic properties of QCD at nonzero isospin chemical potential using improved staggered quarks at physical quark masses. In particular, we discuss the determination of the equation of state at zero and nonzero temperatures and show results. Using the results for the isospin density $n_I$, we also determine the phase diagram in the $(n_I,T)$-plane.

   hep-lathep-phnucl-thPoS(2022)·12 citations
3. 03*

   Heavy-dense QCD at fixed baryon number without a sign problem

   Patrick Bühlmann🇨🇭 · Urs Wenger🇨🇭

   QCD at fixed baryon number can be formulated in terms of transfer matrices explicitly defined in the canonical sectors. In the heavy-dense limit, the fermionic contributions to the canonical partition functions in terms of Polyakov loops and quark occupation numbers turn out to be completely factorized in space. At low temperatures and infinitely strong coupling the sign problem is reduced by orders of magnitude for any baryon number as compared to the corresponding grand-canonical ensemble. In the canonical formulation it is straighforward to integrate out the Polyakov loops in the fermionic weights yielding the partition function as a sum of only baryon occupation numbers in which the sign problem is absent. Using an effective form of the gauge action valid for small values of the gauge coupling, the same can be achieved away from the strong coupling limit in terms of quark occupation numbers and fluxes which couple the quarks with each other. The emerging clusters suggest the construction of algorithms which circumvent the sign problem in the heavy-dense limit including the full gauge action for any value of the gauge coupling.

   hep-latPoS(2022)·3 citations
4. 04*

   $m_c$ (and $m_b$) from lattice QCD

   Andrew T. Lytle🇺🇸

   Quark mass determinations based on lattice QCD simulations have continued to make strides in recent years. Here I review that progress with a focus on developments computing the charm (and bottom) quark masses since the 2015 edition of CHARM. These advances have resulted in groups now quoting (sub-)percent-level precision for these quantities, and, importantly, using a variety of techniques subject to differing systematic uncertainties. Improvements to quantify the effects of QED are also now being included. I will highlight three of the strategies being used to determine $m_c$ at this level of precision.

   hep-lathep-phPoS(2021)·1 citation
5. 05*

   Localisation of Dirac modes in finite-temperature ${\mathbb{Z}}_2$ gauge theory on the lattice

   György Baranka🇭🇺 · Matteo Giordano🇭🇺

   The low-lying Dirac modes become localised at the finite-temperature transition in QCD and in other gauge theories, suggesting a general connection between their localisation and deconfinement. The simplest model where this connection can be tested is ${\mathbb{Z}}_2$ gauge theory in 2+1 dimensions. We show that in this model the low modes in the staggered Dirac spectrum are delocalised in the confined phase and become localised in the deconfined phase. We also show that localised modes correlate with disorder in the Polyakov loop configuration, in agreement with the "sea/island" picture of localisation, and with negative plaquettes. These results further support the conjecture that localisation and deconfinement are closely related.

   hep-latcond-mat.dis-nnPoS(2022)·0 citations
6. 06*

   Approaching the master-field: Hadronic observables in large volumes

   Marco Cè🇨🇭 · Mattia Bruno🇮🇹 · John Bulava🇩🇪 · Anthony Francis🇨🇭 · Patrick Fritzsch🇮🇪 · Jeremy R. Green🇨🇭 · Maxwell T. Hansen🇬🇧 · Antonio Rago🇬🇧

   The master-field approach to lattice QCD envisions performing calculations on a small number of large-volume gauge-field configurations. Substantial progress has been made recently in the generation of such fields, and this must be joined with measurement strategies that take advantage of the large volume. In these proceedings, we describe how to compute simple hadronic quantities efficiently and estimate their errors in the master-field approach, i.e. by studying cross-correlations of observables on a single configuration. We discuss the scaling of the uncertainty with the volume and compare extractions based on momentum-projected and position-space two-point functions. The latter show promising results, already at intermediate volumes, but come with additional technical complexities such as a more complicated manifestation of boundary effects, which we also address.

   hep-latPoS(2022)·10 citations
7. 07*

   Momentum-Current Gravitational Multipoles of Hadrons

   Xiangdong Ji🇺🇸 · Yizhuang Liu🇵🇱

   We study multipole expansion of the momentum currents in hadrons, with three series $S^{(J)}$, ${\tilde{T}}^{(J)}$, and $T^{(J)}$, in connection with the gravitational fields generated nearby. The momentum currents are related to their energy-momentum form factors, which in principle can be probed through processes like deeply-virtual Compton scattering currently studied at JLab 12 GeV facility and future Electron Ion Collider. We define the leading momentum-current multipoles, tensor monopole $\tau$ ($T0$) and scalar quadrupole ${\hat{\sigma }}^{ij}$ ($S2$) moments, relating the former to the so-called $D$-term in the literature. We calculate the momentum current distribution in hydrogen atom and its monopole moment in the basic unit of ${\tau }_0={\hslash }^2/4M$, showing that the sign of $D$-term has little to do with mechanical stability. The momentum current distribution also strongly modifies the static gravitational field inside hadrons.

   ↳ hep-phhep-latnucl-exnucl-thPRD(2022)·49 citations
8. 08*

   The Hubbard model with fermionic tensor networks

   Manuel Schneider🇩🇪 · Johann Ostmeyer🇩🇪 · Karl Jansen🇩🇪 · Thomas Luu🇩🇪 · Carsten Urbach🇩🇪

   Many electromagnetic properties of graphene can be described by the Hubbard model on a honeycomb lattice. However, this system suffers strongly from the sign problem if a chemical potential is included. Tensor network methods are not affected by this problem. We use the imaginary time evolution of a fermionic projected entangled pair state, which allows to simulate both parity sectors independently. Incorporating the fermionic nature on the level of the tensor network allows to fix the particle number to be either even or odd. This way we can access the states at half filling and with one additional electron. We calculate the energy and other observables of both states, which was not possible before with Monte Carlo methods.

   ↳ physics.comp-phcond-mat.str-elhep-latPoS(2022)·5 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.