Wed·Dec 1, 2021Wednesday·December 1, 2021

1. 01*

   Implementation of the conjugate gradient algorithm for heterogeneous systems

   Salvatore Cali🇺🇸 · William Detmold🇺🇸 · Grzegorz Korcyl🇵🇱 · Piotr Korcyl🇵🇱 · Phiala Shanahan🇺🇸

   Lattice QCD calculations require significant computational effort, with the dominant fraction of resources typically spent in the numerical inversion of the Dirac operator. One of the simplest methods to solve such large and sparse linear systems is the conjugate gradient (CG) approach. In this work we present an implementation of CG that can be executed on different devices, including CPUs, GPUs, and FPGAs. This is achieved by using the SYCL/DPC++ framework, which allows the execution of the same source code on heterogeneous systems.

   hep-latPoS(2022)·1 citation
2. 02*

   Lattice artefacts on the Landau gauge gluon propagator from hypercubic tensor representations

   Guilherme Catumba🇪🇸 · Orlando Oliveira🇵🇹 · Paulo J. Silva🇵🇹

   Lattice tensor representations are used to investigate the lattice Landau gauge gluon propagator for the 4-dimensional pure SU(3) Yang-Mills gauge theory. Due to the different symmetry structure of hypercubic lattices compared to the continuum space-time, lattice correlation functions are described by different tensor structures. Therefore, form factors describing lattice correlation functions have, in principle, non-trivial relations with the continuum counterparts. The use of several tensor bases respecting lattice symmetries, and the analysis of its completeness allows to quantify the deviations of the lattice results from the continuum theory, and also estimate the theoretical uncertainty in the propagator. Furthermore, our analysis tests continuum based relations with the lattice data and shows that the lattice Landau gauge gluon propagator is suitably described by a unique form factor, as in the continuum formulation. Additionally, we identified classes of kinematic configurations where these deviations are minimal and the continuum description of lattice tensors is improved.

   hep-latPoS(2022)·1 citation
3. 03*

   Color superconductivity in a small box: a complex Langevin study

   Shoichiro Tsutsui🇯🇵 · Yuhma Asano🇯🇵 · Yuta Ito🇯🇵 · Hideo Matsufuru🇯🇵 · Yusuke Namekawa🇯🇵 · Jun Nishimura🇯🇵 · Asato Tsuchiya🇯🇵 · Takeru Yokota🇯🇵

   It is expected that the color superconductivity (CSC) phase appears in QCD at low temperature and high density. On the basis of the lattice perturbation theory, a possible parameter region in which the CSC occurs has been predicted. In this work, we perform complex Langevin simulation on an $8^3\times 128$ lattice using four-flavor staggered fermions. We find, in particular, that the quark number has plateaux with respect to the chemical potential similar to our previous study, indicating the formation of the Fermi sphere. A diquark-antidiquark operator, which is an order parameter of color superconductivity, is formulated on the lattice using the U(1) noise. Our result for this operator is found to fluctuate violently when the Fermi surface coincides with the energy levels of quarks. We also discuss partial restoration of the chiral symmetry at high density.

   hep-latPoS(2022)·9 citations
4. 04*

   Single static-quark system above $T_c$ investigated by energy-momentum tensor in SU(3) Yang-Mills theory

   Masakiyo Kitazawa🇯🇵 · Ryosuke Yanagihara🇯🇵 · Masayuki Asakawa🇯🇵 · Tetsuo Hatsuda🇯🇵

   We investigate the distribution of energy-momentum tensor (EMT) around a static quark in the deconfined phase of SU(3) Yang-Mills theory. The EMT defined through the gradient-flow formalism is used for the numerical analysis of the EMT distribution around the Polyakov loop with the continuum extrapolation. Using EMT, one can study the mechanical distortion of the color gauge field induced by the static charge. We find substantial separation in the absolute values of the EMT eigenvalues which is not observed in Maxwell theory. The separation grows as temperature is lowered toward the critical temperature. The lattice data also indicate the thermal screening at long distance and the perturbative behavior at short distance.

   hep-latPoS(2022)·3 citations
5. 05*

   Three-dimensional Gross-Neveu model with two flavors of staggered fermions

   Sandip Maiti🇮🇳 · Debasish Banerjee🇮🇳 · Shailesh Chandrasekharan🇺🇸 · Marina Krstic Marinkovic🇨🇭

   We introduce a strongly interacting lattice field theory model containing two flavors of massless staggered fermions with two kinds of interactions: (1) a lattice current-current interaction, and (2) an on-site four-fermion interaction. At weak couplings, we expect a massless fermion phase since our interactions become irrelevant at long distances. At strong couplings, based on previous studies, we argue that our lattice model contains two different massive fermion phases with different mechanisms of fermion mass generation. In one phase, fermions become massive through Spontaneous Symmetry Breaking (SSB) via the formation of a fermion bilinear condensate. In the other phase, fermion mass arises through a more exotic mechanism without the formation of any fermion bilinear condensate. Our lattice model is free of sign problems and can be studied using the fermion bag algorithm. The longer term goal here is to study both these mass generation phenomena in a single model and understand how different phases come together.

   hep-latcond-mat.str-elhep-thPoS(2022)·2 citations
6. 06*

   Emergence of the rho resonance from the HAL QCD potential

   Yutaro Akahoshi🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵

   In this article, we report the $\rho$ resonance study using the HAL QCD method. We calculate the $I=1$ $\pi \pi$ potential at $m_{\pi }\approx 0.41$ GeV by a combination of the one-end trick, sequential propagator and covariant approximation averaging (CAA). Thanks to those techniques, we determine the non-local $I=1$ $\pi \pi$ potential at the next-to-next-to-leading order (N${}^2$LO) of the derivative expansion for the first time and obtain the pole of the S-matrix corresponding to the $\rho$ resonance. We also discuss the comparison between our result and a previous calculation, done by Lüscher's method.

   hep-lathep-phPoS(2022)·1 citation
7. 07*

   Quark-diquark potential and diquark mass from Lattice QCD

   Kai Watanabe🇯🇵

   We propose a new application of lattice QCD to calculate the quark-diquark potential, diquark mass and quark mass required for the diquark model. As a concrete example, we consider the ${\Lambda }_c$ baryon and treat it as a charm-diquark($c$-[$ud$]) two-body bound state. We extend the HAL QCD method to calculate the charm-diquark potential which reproduces the equal-time Nambu-Bethe-Salpeter wave function of the S-wave state (${\Lambda }_c({\frac{1}{2}}^{+})$). The diquark mass is determined so as to reproduce the difference between the S-wave and the spin-orbit averaged P-wave energies, i.e. the difference between the ${\Lambda }_c({\frac{1}{2}}^{+})$ level and the average of the ${\Lambda }_c({\frac{1}{2}}^{-})$ and the ${\Lambda }_c({\frac{3}{2}}^{-})$ levels. Numerical calculations are performed on a $32^3\times 64$ lattice with lattice spacing of $a\simeq 0.0907$ fm and the pion mass of $m_{\pi }\simeq 700$ MeV. Our charm-diquark potential is given by the Coulomb+linear (Cornell) potential where the long range behavior is consistent with the charm-anticharm potential while the Coulomb attraction is considerably smaller. This weakening of the attraction may be attributed to the diquark size effect. The obtained diquark mass is $m_D=1.273(44)$ GeV. Our diquark mass lies slightly above the conventional estimates, namely the $\rho$ meson mass and twice the constituent quark mass $2m_N/3$.

   hep-latPRD(2022)·20 citations
8. 08*

   $\ell N$ inclusive scattering cross sections on the lattice

   Jun-Sik Yoo🇯🇵 · Shoji Hashimoto🇯🇵 · Hiroshi Ohki🇯🇵

   Utilizing the approach recently proposed for the $\ell N$ inclusive scattering cross section on the lattice, we compute the differential scattering cross section for the charged current process $\ell p\to \nu n$ for various kinematical channels. The simulation is carried out on the 2+1 flavor $16^3\times 32$ ensemble with Iwasaki and Domain Wall Fermion action. The lattice results are compared with MINER$\nu$A result for the equivalent process.

   hep-lathep-phPoS(2022)·0 citations
9. 09*

   Spectral sum from Euclidean lattice correlators and determination of renormalization constants

   Tsutomu Ishikawa🇯🇵 · Shoji Hashimoto🇯🇵 · Takashi Kaneko🇯🇵

   We propose a new method to renormalize lattice operators. The method is based on the technique to compute the spectral sum appearing in the Shifman-Vainshtein-Zakharov QCD sum rule from lattice correlators. The application of this technique to the light quark system is useful for operator renormalization as well as for the test of perturbative QCD and OPE. We determine the renormalization constant of the vector current and discuss extensions to other current operators.

   hep-lathep-phPoS(2022)·1 citation
10. 10*

    A Fresh Look at the Chemical Potential on the Lattice

    Rajiv V. Gavai🇮🇳

    Lattice techniques are the most reliable ones to investigate the QCD phase diagram in the temperature-baryon density (chemical potential) plane. These techniques are, however, well-known to be saddled with a variety of problems at nonzero density. I address here the old question of placing the baryonic (quark) chemical potential on the lattice and point out its important consequences for the current and future experimental searches of the QCD critical point.

    hep-lathep-phPoS(2022)·0 citations
11. 11*

    Renormalization $\&$ improvement of the tensor operator for $N_f=3$ QCD in a $\chi$SF setup

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

    We present preliminary results of the non-perturbative renormalization group (RG) running of the flavor non-singlet tensor operator. We employ the $\chi$SF scheme for $N_f=3$ QCD using ensembles generated by the ALPHA collaboration for the computation of the quark mass running. The $\chi$SF property of automatic $O(a)$ improvement prevents the $O(a)$ mixing of the correlation functions.

    hep-latPoS(2022)·2 citations
12. 12*

    Window contributions to the muon hadronic vacuum polarization with twisted-mass fermions

    Davide Giusti🇩🇪 · Silvano Simula🇮🇹

    We present a lattice calculation of the Euclidean position-space windows contributing to the leading-order hadronic vacuum polarization term of the muon anomalous magnetic moment $a_{\mu }$. Short-, intermediate- and long-distance windows are considered in order to isolate different scales sensitive to specific integration ranges of experimental time-like data used in the R-ratio. By adopting the same smooth window function introduced by the RBC and UKQCD Collaborations with width parameter $\Delta =0.15\mathrm{fm}$, for the isospin-symmetric, light, quark-connected component we get $a_{\mu }^{\mathrm{SD}}(ud)=48.21(80)\cdot 10^{-10}$ , $a_{\mu }^{\mathrm{W}}(ud)=202.2(2.6)\cdot 10^{-10}$ and $a_{\mu }^{\mathrm{LD}}(ud)=382.5(11.7)\cdot 10^{-10}$ in the short- (SD), intermediate- (W) and long-distance (LD) time regions, respectively, with $t_0=0.4\mathrm{fm}$ and $t_1=1.0\mathrm{fm}$. Our results are obtained using the gauge configurations generated by the Extended Twisted Mass Collaboration with $N_f=2+1+1$ dynamical quarks, at three values of the lattice spacing varying from 0.089 to 0.062 fm, at several lattice volumes and with pion masses in the range $M_{\pi }\simeq 220-490\mathrm{MeV}$.

    hep-lathep-phPoS(2022)·29 citations
13. 13*

    Mixed adjoint-fundamental matter and applications towards SQCD and beyond

    Georg Bergner🇩🇪 · Stefano Piemonte🇩🇪

    Gauge theories with fermions in adjoint and fundamental representations are relevant for many different applications including composite Higgs models and general aspects of the confinement problem. We present first results from simulations of SU(2) gauge theory with two Dirac fermions in the fundamental representation and one adjoint flavor. In this context, we also discuss applications towards simulations of supersymmetric QCD.

    hep-lathep-thPoS(2022)·9 citations
14. 14*

    Quark mass RG-running for $N_f$ =3 QCD in a $\chi SF$ setup

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

    We compute the nonperturbative quark mass RG-running in the range ${\Lambda }_{QCD}⪅\mu ⪅M_W$ for $N_f=3$ massless QCD with a mixed action approach: sea quarks are regularised using nonperturbatively $O(a)$-improved Wilson fermions with Schrödinger functional (SF) boundary conditions, employing the configurations of 1802.05243, while valence quarks are regularised using nonperturbatively $O(a)$-improved Wilson fermions with chirally rotated Schrödinger functional boundary conditions ($\chi$SF). Our result is compatible with its SF counterpart of ref.1802.05243, confirming the universality of $\chi$SF and SF in the continuum limit. We also establish the optimal tuning strategy for the critical hopping parameter ${\kappa }_c$ and the $\chi$SF boundary counterterm coefficient $z_{\mathrm{f}}$. We work in two energy regimes with two different definitions of the coupling: SF-coupling for 2 GeV $⪅\mu ⪅M_W$ and GF-coupling for ${\Lambda }_{QCD}⪅\mu ⪅2GeV$.

    hep-latPoS(2022)·2 citations
15. 15*

    QCD topology and axion's properties from Wilson twisted mass lattice simulations

    A.Yu. Kotov🇩🇪 · M.P. Lombardo🇮🇹 · A. Trunin🇷🇺

    We present the results on topological susceptibility and chiral observables in $N_f=2+1+1$ QCD for temperature range $120<T<600$ MeV. The lattice simulations are performed with Wilson twisted mass fermions at physical pion, strange and charm masses. In high-$T$ region $T\gtrsim 300$ MeV the chiral observables are shown to follow leading order Griffith analyticity, and the topological susceptibility follows a power-law decay as in the instanton dilute gas models. The measured topological susceptibility is used to estimate the mass of QCD axion. The resulting axion mass constraints are in agreement with our previous studies at higher pion masses.

    hep-lathep-phhep-thPoS(2022)·10 citations
16. 16*

    In-medium static quark potential from spectral functions on realistic HISQ ensembles

    Gaurang Parkar🇳🇴 · Dibyendu Bala🇩🇪 · Olaf Kaczmarek🇩🇪 · Rasmus Larsen🇳🇴 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Alexander Rothkopf🇳🇴 · Johannes Heinrich Weber🇩🇪

    We explore the interactions between a quark anti-quark pair in a thermal medium based on lattice QCD ensembles with $N_f=2+1$ dynamical HISQ flavors. Our dataset spans the phenomenologically relevant temperature range between T=140MeV-2GeV based on lattice sizes $N_{\tau }=10,12$ and $16$, with an aspect ratio of $N_{\sigma }/N_{\tau }=4$. The peak position $\Omega$ and the width $\Gamma$ of the spectral function of Wilson-line correlators in Coulomb gauge is computed. We assess the information content in the correlation functions and deploy three complementary strategies to reconstruct spectral information: model fits, Padé approximation and the Bayesian BR method. Limitations of each approach are carefully assessed.

    hep-latPoS(2022)·1 citation
17. 17*

    Scattering from generalised lattice ${\varphi }^4$ theory

    Marco Garofalo🇩🇪 · Fernando Romero-López🇺🇸 · Akaki Rusetsky🇩🇪 · Carsten Urbach🇩🇪

    We investigate numerically different techniques to extract scattering amplitudes from the Euclidean Lattice {\phi}4 theory with two fields, having different masses. We present an exploratory study of the recently proposed method by Bruno and Hansen for extracting the scattering length from a four-point function (cf 10.1007/JHEP06(2021)043), and a study of the two- and three-particle quantization condition.

    hep-latPoS(2022)·2 citations
18. 18*

    Exotics in the $\pi D$ system

    Eric B. Gregory🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Stefan Krieg🇩🇪 · Thomas Luu🇩🇪

    In this proceedings we consider several states, namely the $D_{s0}^{\ast }(2317)$, $D_{s1}(2460)$, $D_0^{\ast }(2300)$ and $D_1(2430)$, which appear to defy description as simple quark-antiquark pairs. Theoretical input from unitarized chiral perturbation theory suggests they can be understood as emerging from Goldstone-Boson--$D$-meson scattering. We present results from an $SU(3)$ flavor-symmetric lattice QCD simulation at large pion masses suggesting that there exists a $\pi D$ bound state in the flavor-sextet representation that cannot emerge for quark-antiquark states, but that appears naturally from the multiquark states. Moreover, we find repulsion in the [15] representation, which establishes the pattern predicted for the interactions of Goldstone bosons with $D$ mesons. This suggests these states may have the structure of hadronic molecules.

    hep-lathep-phPoS(2022)·2 citations
19. 19*

    Investigations of decuplet baryons from meson-baryon interactions in the HAL QCD method

    Kotaro Murakami🇯🇵 · Yutaro Akahoshi🇯🇵 · Sinya Aoki🇯🇵 · Kenji Sasaki🇯🇵

    We study decuplet baryons from meson-baryon interactions, in particular, $\Delta$ and $\Omega$ baryons from P-wave $I=3/2$ $N\pi$ and $I=0$ $\Xi \bar{K}$ interactions, respectively. The interaction potentials are calculated in the HAL QCD method using 3-quark-type source operators at $m_{\pi }\approx 410\text{MeV}$. We use the conventional stochastic estimation of all-to-all propagators combined with the all-mode averaging to reduce statistical fluctuations. We have found that two potentials have quite similar behaviors, suggesting that a mass difference between $\Delta$ and $\Omega$ comes mainly from a difference of kinematical structure between $N\pi$ and $\Xi \bar{K}$, rather than their interactions. The scattering phase shifts calculated from the potentials indicate that $\Delta$ and $\Omega$ baryons exist as bound states in this lattice setup, whose binding energies are consistent with those obtained from 2-point functions.

    hep-lathep-phnucl-thPoS(2022)·0 citations
20. 20*

    A new framework to tune an improved relativistic heavy-quark action

    Davide Giusti🇩🇪 · Christoph Lehner🇩🇪

    We introduce a new non-perturbative method to tune the parameters of the Columbia formulation of an anisotropic, clover-improved relativistic heavy-quark (RHQ) action. By making use of suitable observables which can be computed at a sequence of heavy-quark mass values, employing an $O(a)$-improved discretized action with domain-wall chiral fermion, and safely interpolated between the accessible heavy-quark mass region and the static point predicted by heavy-quark effective theory, we are able to precisely determine the unknown coefficients of the RHQ action. In this proof-of-principle study we benefit from the RBC/UKQCD Iwasaki gauge configurations with $2+1$ flavors of dynamical quarks, at three values of the lattice spacing varying from $0.11$ to $0.062$ fm. Preliminary results and applications to bottom spectroscopy are also presented.

    hep-latPoS(2022)·2 citations
21. 21*

    Lattice QCD at Imaginary Chemical Potential in the Chiral Limit

    D. A. Clarke🇩🇪 · Jishnu Goswami🇩🇪 · F. Karsch🇩🇪 · Anirban Lahiri🇩🇪 · M. Neumann🇩🇪 · C. Schmidt🇩🇪

    We report on an ongoing study on the interplay between Roberge-Weiss (RW) and chiral transitions in simulations of (2+1)-flavor QCD with an imaginary chemical potential. We established that the RW endpoint belongs to the 3-$d$, $Z_2$ universality class when calculations are done with the Highly Improved Staggered Quark (HISQ) action in the RW plane with physical quark masses. We also have explored a range of quark masses corresponding to pion mass values, $m_{\pi }\ge 40$~MeV and found that the transition is consistent with $Z_2$ universality class. We argue that observables that were usually used to determine the chiral phase transition temperature, e.g. the chiral condensate and chiral susceptibility, are sensitive to the RW transition and are energy-like observables for the $Z_2$ transition, contrary to the magnetic-like (order parameter) behavior at vanishing chemical potential. Moreover the calculations performed at $m_{\pi }\sim 40$~MeV also put a stringent constraint for a critical pion mass at zero chemical potential for a possible first-order chiral phase transition.

    hep-lathep-phnucl-thPoS(2022)·1 citation
22. 22*

    Model-Independent Error Mitigation in Parametric Quantum Circuits and Depolarizing Projection of Quantum Noise

    Xiaoyang Wang🇨🇳 · Xu Feng🇨🇳 · Lena Funcke🇨🇦 · Tobias Hartung🇬🇧 · Karl Jansen🇩🇪 · Stefan Kühn🇨🇾 · Georgios Polykratis🇨🇾 · Paolo Stornati🇪🇸

    Finding ground states and low-lying excitations of a given Hamiltonian is one of the most important problems in many fields of physics. As a novel approach, quantum computing on Noisy Intermediate-Scale Quantum (NISQ) devices offers the prospect to efficiently perform such computations and may eventually outperform classical computers. However, current quantum devices still suffer from inherent quantum noise. In this work, we propose an error mitigation scheme suitable for parametric quantum circuits. This scheme is based on projecting a general quantum noise channel onto depolarization errors. Our method can efficiently reduce errors in quantum computations, which we demonstrate by carrying out simulations both on classical and IBM's quantum devices. In particular, we test the performance of the method by computing the mass gap of the transverse-field Ising model using the variational quantum eigensolver algorithm.

    ↳ quant-phhep-latPoS(2022)·7 citations
23. 23*

    Manifestly gauge invariant exact renormalization group for quantum electrodynamics

    Yuki Miyakawa🇯🇵 · Hidenori Sonoda🇯🇵 · Hiroshi Suzuki🇯🇵

    We formulate quantum electrodynamics on the basis of gauge (or BRST) covariant diffusion equations of fields. This is a particular example of the gradient flow exact renormalization group (GFERG). The resulting Wilson action fulfills a simple gauge Ward--Takahashi identity. We solve the GFERG equation around the Gaussian fixed point to the second order in gauge coupling and obtain the 1-loop beta function and anomalous dimensions. The anomalous dimension of the electron field coincides with that of the fermion field diffused by a gauge covariant flow equation of Lüscher.

    ↳ hep-thhep-latPTEP(2022)·11 citations
24. 24*

    Real time dynamics of a semiclassical gravitational collapse of a scalar quantum field

    Jana N. Guenther🇩🇪 · Christian Hoelbling🇩🇪 · Lukas Varnhorst🇩🇪

    We present a new formalism for numerically treating the semiclassical gravitational collapse of a scalar quantum field in the radially symmetric case. Our formalism is time reversal invariant and the evolution of the scalar fields is unitary. We present some first results in the angular momentum $l=0$ approximation for an initially coherent state of a massless field and briefly discuss future prospects.

    ↳ gr-qchep-latPoS(2022)·5 citations
25. 25*

    Fermion and gluon spectral functions far from equilibrium

    Kirill Boguslavski🇦🇹 · Tuomas Lappi🇫🇮 · Sören Schlichting🇩🇪

    Motivated by the quark-gluon plasma, we develop a simulation method to obtain the spectral function of (Wilson) fermions non-perturbatively in a non-Abelian gauge theory with large gluon occupation numbers [arXiv:2106.11319]. We apply our method to a non-Abelian plasma close to its non-thermal fixed point, i.e., in a far-from-equilibrium self-similar regime, and find mostly very good agreement with perturbative hard loop (HTL) calculations. For the first time, we extract the full momentum dependence of the damping rate of fermionic collective excitations and compare our results to recent non-perturbative extractions of gluonic spectral functions in two and three spatial dimensions [arXiv:2101.02715, arXiv:1804.01966].

    ↳ hep-phhep-latnucl-thEPJ Web Conf.(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.