Thu·Oct 28, 2021Thursday·October 28, 2021

1. 01*

   Finite-density QCD, $\mathcal{P}\mathcal{T}$ symmetry, and dual algorithms

   Moses A. Schindler · Stella T. Schindler · Michael C. Ogilvie🇺🇸

   Finite-density QCD and many other field theories with sign problems have a $\mathcal{P}\mathcal{T}$-type symmetry. After a brief introduction to $\mathcal{P}\mathcal{T}$-symmetric field theories, a real dual representation for $\mathcal{P}\mathcal{T}$-symmetric scalar field theories with complex actions is derived. We show that $\mathcal{P}\mathcal{T}$-symmetric field theories can exhibit exotic behavior, including sinusoidally modulated propagators, disorder lines, and spatially inhomogeneous pattern-forming phases. We discuss the interplay of duality, $\mathcal{P}\mathcal{T}$-symmetry and pattern formation using a ${\varphi }^4$ model and $Z(N)$ spin model with sign problems as examples. These behaviors may occur in finite-density QCD and related models.

   hep-lathep-phPoS(2022)·7 citations
2. 02*

   Determination of hybrid charmonium meson masses

   Gaurav Ray🇬🇧 · Craig McNeile🇬🇧

   We report initial results from our study of the masses and decay constants of the lightest multiplet of charmonium-like hybrid mesons. We obtain precise measurements of the $1^{-+}$ state through the use of a variational basis and a large number of configurations at three lattice spacings. We use staggered fermion operators using configurations generated with the HISQ action with 2+1+1 dynamical flavours. The mixing of the vector hybrid with the $J/\psi$ is examined and a preliminary bound on the vector hybrid decay constant is presented.

   hep-latPoS(2022)·4 citations
3. 03*

   Regularisation in Nonperturbative Extensions of Effective Field Theory

   Curtis D. Abell🇦🇺 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺 · Jia-Jun Wu🇨🇳

   The process of renormalisation in nonperturbative Hamiltonian Effective Field Theory (HEFT) is examined in the $\Delta$-resonance scattering channel. As an extension of effective field theory incorporating the Lüscher formalism, HEFT provides a bridge between the infinite-volume scattering data of experiment and the finite-volume spectrum of energy eigenstates in lattice QCD. HEFT also provides phenomenological insight into the basis-state composition of the finite-volume eigenstates via the state eigenvectors. The Hamiltonian matrix is made finite through the introduction of finite-range regularisation. The extent to which the established features of this regularisation scheme survive in HEFT is examined. In a single-channel $\pi N$ analysis, fits to experimental phase shifts withstand large variations in the regularisation parameter, $\Lambda$, providing an opportunity to explore the sensitivity of the finite-volume spectrum and state composition on the regulator. While the Lüscher formalism ensures the eigenvalues are insensitive to $\Lambda$ variation in the single-channel case, the eigenstate composition varies with $\Lambda$; the admission of short distance interactions diminishes single-particle contributions to the states. In the two-channel $\pi N$, $\pi \Delta$ analysis, $\Lambda$ is restricted to a small range by the experimental data. Here the inelasticity is particularly sensitive to variations in $\Lambda$ and its associated parameter set. This sensitivity is also manifest in the finite-volume spectrum for states near the opening of the $\pi \Delta$ scattering channel. Finally, HEFT has the unique ability to describe the quark-mass dependence of the finite-volume eigenstates. The robust nature of this capability is presented and used to confront current state-of-the-art lattice QCD calculations.

   hep-lathep-phnucl-thPRD(2022)·21 citations
4. 04*

   Gluon Parton Distribution of the Pion and Nucleon from Lattice QCD

   Zhouyou Fan🇺🇸 · Huey-Wen Lin🇺🇸

   We present the $x$-dependent nucleon and pion gluon distribution from lattice QCD using the pseudo-PDF approach, on lattice ensembles with $2+1+1$ flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration. We use clover fermions for the valence action and momentum smearing to achieve pion boost momentum up to 2.56~GeV on three lattice spacings $a\approx 0.9,0.12$ and 0.15~fm and three pion masses $M_{\pi }\approx 220$, 310 and 690~MeV. We compare our pion and preliminary nucleon gluon results with the determination by global fits.

   hep-lathep-phnucl-thPoS(2022)·5 citations
5. 05*

   Tetraquark channels with $\bar{b}b$ pair in the static limit

   Mitja Sadl🇸🇮 · Sasa Prelovsek🇸🇮

   Belle experiment discovered two hadrons with exotic quark content $Z_b^{+}\simeq \bar{b}b\bar{d}u$. We present a lattice study of the $\bar{b}b\bar{d}u$ systems with various quantum numbers using static bottom quarks. Only one set of quantum numbers that couples to $Z_b$ and ${\rm Y}\pi$ was explored on the lattice before: these studies found an attractive potential between $B$ and ${\bar{B}}^{\ast }$ which leads to a bound state below the threshold. In the present study, we consider the other three sets of quantum numbers. Eigen-energies of the $\bar{b}b\bar{d}u$ system are extracted as a function of separation between $b$ and $\bar{b}$. The resulting eigen-energies do not show any sizable deviation from non-interacting energies of the systems $\bar{b}b+\bar{d}u$ and $\bar{b}u+\bar{d}b$, so no significant attraction or repulsion is found. A slight exception is a small attraction between $B$ and ${\bar{B}}^{\ast }$ at small distance for the quantum number that couples to $Z_b$ and ${\eta }_b\rho$.

   hep-lathep-phPoS(2022)·2 citations
6. 06*

   Monte Carlo simulations of phonon propagation in the Fermi-sea of Weyl spinors and detection of hysteresis effects using Groupoids

   Sadataka Furui🇯🇵 · Serge Dos Santos

   We considered symplectic quaternions sitting on a $(2+1)D$ lattice in momentum space which interact with nearest neighbor interactions. The action is expressed by fixed point actions given by the superposition of blocks whose length of the contour is 4, 6 or 8 lattice spacings. The spinors are on a finite $2D$ plane expressed as $u_{1}a{e}_1+u_{2}a{e}_2$ (A type) and/or on two $2D$ planes separated by $\pm a{e}_1\wedge e_2$ (B type). In the A type, link actions on counter-clockwise rotating loop and on clockwise rotating loop cancel, however in the B type, the direction of links between the lower $2D$ plane and the upper $2D$ plane induces differences in the action. The time-reversal conserving and spin rotational symmetry breaking actions can be measured. Result of Monte-Carlo simulations of $64\times 64$, $128\times 128$ and $256\times 256$ spatial lattices are presented.

   hep-lat1 citation
7. 07*

   Negative string tension of higher-charge Schwinger model via digital quantum simulation

   Masazumi Honda🇯🇵 · Etsuko Itou🇯🇵 · Yuta Kikuchi🇺🇸 · Yuya Tanizaki🇯🇵

   We study some properties of generalized global symmetry for the charge-$q$ Schwinger model in the Hamiltonian formalism, which is the $(1+1)$-dimensional quantum electrodynamics with a charge-$q$ Dirac fermion. This model has the ${\mathbb{Z}}_q$ $1$-form symmetry, which is a remnant of the electric $U(1)$ $1$-form symmetry in the pure Maxwell theory. It is known that if we put the theory on closed space, then the Hilbert space is decomposed into $q$ distinct sectors, called universes and some states with higher energy density do not decay to the ground state due to the selection rule of the $1$-form symmetry. Even with open boundaries, we can observe the stability of such states by seeing a negative string tension behavior, meaning that opposite charges repel with each other. We develop a method based on the adiabatic state preparation to see this feature with digital quantum simulation and confirm it using a classical simulator of quantum devices. Especially, we measure local energy density and see how it jumps between inside and outside of insertion of the probe charges. We explicitly see that the energy density inside is lower than the outside one. This is a clear signature of the negative string tension.

   ↳ hep-thcond-mat.str-elhep-latquant-phPTEP(2022)·36 citations
8. 08*

   Electromagnetic form factors of baryons in nuclear medium

   G. Ramalho🇧🇷 · K. Tsushima🇧🇷 · J.P.B.C. de Melo🇧🇷

   The electromagnetic structure of the baryons is modified in the nuclear medium. The modifications can be inferred from the comparison between the electromagnetic form factors in medium with the respective form factor in vacuum. Of particular interest is the ratio between the electric and magnetic form factors in medium ($G_E^{\ast }/G_M^{\ast }$) and vacuum ($G_E/G_M$) of the octet baryon. The deviation of the double ratios ($G_E^{\ast }/G_M^{\ast })/(G_E/G_M)$ from unity measures the impact of the medium modification of the electromagnetic structure in a nuclear medium. Measurements of the double ratios $(G_E^{\ast }/G_M^{\ast })/(G_E/G_M)$ for different nuclear densities may become available in a near future using the polarization-transfer method developed at Jefferson Lab. We present estimates of the double ratios of octet baryons based on a covariant constituent quark model, which takes into account pion cloud excitations of the baryon cores,for different nuclear densities. Our results manifest different features, namely, enhancement or quenching depending on the baryon flavor content.

   ↳ hep-phhep-exhep-latnucl-ex+1PoS(2022)·1 citation

* 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.