HEP Lattice·hep-lat

Tue·Nov 2, 2021Tuesday·November 2, 2021

22 papers—18 primary·4 cross-listed·reconstructed*

01*
Lattice QCD results for the topological up-quark mass contribution: too small to rescue the $m_{u} = 0$ solution to the strong CP problem
Constantia Alexandrou🇨🇾 · Jacob Finkenrath🇨🇾 · Lena Funcke🇺🇸 · Karl Jansen🇩🇪 · Bartosz Kostrzewa🇩🇪 · Ferenc Pittler🇨🇾 · Carsten Urbach🇩🇪
A vanishing Yukawa coupling of the up quark could in principle solve the strong CP problem. To render this solution consistent with current algebra results, the up quark must receive an alternative mass contribution that conserves CP symmetry. Such a contribution could be provided by QCD through non-perturbative topological effects, including instantons. In this talk, we present the first direct lattice computation of this topological mass contribution, using gauge configurations generated by the Extended Twisted Mass collaboration. We use the Iwasaki gauge action, Wilson twisted mass fermions at maximal twist, and dynamical up, down, strange and charm quarks. Our result for the topological mass contribution is an order of magnitude too small to account for the phenomenologically required up-quark mass. This rules out the "massless" up-quark solution to the strong CP problem, in accordance with previous results relying on $χ$ PT fits to lattice data. The talk is based on [Alexandrou et al., PRL 125, 232001 (2020)], where more details can be found.
hep-lathep-phPoS(2022)·0 citations
02*
Introducing Fermionic Link Models
Debasish Banerjee🇮🇳 · Emilie Huffman🇨🇦 · Lukas Rammelmüller🇩🇪
Quantum link models (QLMs) are extensions of Wilson-type lattice gauge theories, and show rich physics beyond the phenomena of conventional Wilson gauge theories. Here we explore the physics of $U (1)$ symmetric QLMs, both using a more conventional quantum spin-1/2 representation, as well as a fermionic representation. In 2D, we show that both bosonic and fermionic QLMs display the same physics. We then explore the models in 3D and find different behavior for the two QLMs. For the bosons, we see evidence for a quantum phase transition from a symmetry broken phase to a potential quantum spin liquid phase. For the fermions, we identify not one but two distinct phases in addition to a symmetry broken phase. We explore the symmetries of the ground state in the strong coupling limit, which breaks lattice symmetries and examine the spectrum for both models.
hep-latPoS(2022)·3 citations
03*
Efficient computations of continuous action densities of states for lattice models
Biagio Lucini🇬🇧 · Olmo Francesconi🇩🇰 · Markus Holzmann🇫🇷 · David Lancaster🇬🇧 · Antonio Rago🇬🇧
The Logarithmic Linear Relaxation (LLR) algorithm is an efficient method for computing densities of states for systems with a continuous spectrum. A key feature of this method is exponential error reduction, which allows us to evaluate the density of states of a system over hundreds of thousands of orders of magnitude with a fixed level of relative accuracy. As a consequence of exponential error reduction, the LLR method provides a robust alternative to traditional Monte Carlo calculations in cases in which states suppressed by the Boltzmann weight play nevertheless a relevant role, e.g., as transition regions between dominant configuration sets. After reviewing the algorithm, we will show an application in U(1) Lattice Gauge Theory that has enabled us to obtain the most accurate estimate of the critical coupling with modest computational resources, defeating exponential tunneling times between metastable vacua. As a further showcase, we will then present an application of the LLR method to the decorrelation of the topological charge in SU(3) Lattice Gauge Theory near the continuum limit. Finally, we will review in general applications of the LLR algorithm to systems affected by a strong sign problem and discuss the case of the Bose gas at finite chemical potential.
hep-latcond-mat.stat-mechcond-mat.str-elJ.Phys.Conf.Ser.(2022)·2 citations
04*
Large $N$ simulation of the twisted reduced matrix model with an adjoint Majorana fermion
Pietro Butti (1 and 2)🇪🇸 · Margarita García Pérez (1)🇪🇸 · Antonio González-Arroyo (1 and 2)🇪🇸 · Ken-Ichi Ishikawa (3 and 4)🇯🇵 · Masanori Okawa (4) ((1) IFT UAM-CSIC, Universidad Autónoma de Madrid, (2) DFT, Universidad Autónoma de Madrid, (3) Core-U, GSASE, Hiroshima U. (4) GSASE, Hiroshima U.)
To investigate the properties of the large $N$ limit of $N = 1$ SUSY Yang-Mills theory, we have started a study for a reduced matrix model with an adjoint Majorana fermion. The gauge action is based on the Wilson action and the adjoint-fermion one is the Wilson-Dirac action on a reduced lattice with twisted gauge boundary condition. We employ the RHMC algorithm in which the absolute value of the Pfaffian is incorporated. The sign of the Pfaffian is included with the re-weighting method and separately measured as an observable. In this talk, we show the configuration generation status towards the large $N$ limit and the behavior of the lowest/lower eigenvalue(s) of the Wilson-Dirac adjoint fermion operator. We investigated the sign of the Pfaffian and the critical hopping parameters for the chiral limit. The sign of the Pfaffian is always positive on the configurations we have generated. The critical hopping parameters derived from the eigenvalues of the Dirac operator are consistent with those derived from the PCAC mass relation with non-singlet flavor adjoint fermions.
hep-latPoS(2021)·2 citations
05*
The Polyakov loop models in the large N limit: Phase diagram at finite density
O. Borisenko🇺🇦 · V. Chelnokov🇩🇪 · S. Voloshyn🇺🇦
The 't Hooft-Veneziano limit of various U(N) and SU(N) Polyakov loop models is constructed at finite temperature and non-zero baryon chemical potential. In this paper we calculate the free energy, its derivatives, the Polyakov loop expectation values and the baryon density. The phase diagram is described in details.
hep-lathep-thPRD(2022)·7 citations
06*
Perturbative study of the Gluino-Glue operator in SYM
Marios Costa🇨🇾 · George Panagopoulos🇺🇸 · Haralambos Panagopoulos🇨🇾 · Gregoris Spanoudes🇨🇾 · Herodotos Herodotou🇨🇾 · Phivos Philippides🇨🇾
We investigate the renormalization of the Gluino-Glue operator, using both Lattice Perturbation Theory (LPT) and a Gauge Invariant Renormalization Scheme (GIRS). The latter scheme involves gauge-invariant Green's functions of two operators at different space-time points, which can be also computed via numerical simulations. There is no need to fix a gauge and the mixing with gauge noninvariant operators is inconsequential. We calculate perturbatively the conversion factor relating GIRS with the Modified Minimal Subtraction scheme. On the other hand, the Gluino-Glue operator being mixes with several gauge noninvariant operators which have the same quantum numbers. The determination of the mixing matrix on the lattice demands the calculation of 2-pt and 3-pt Green's functions with external gluon, gluino and ghost fields using LPT. We compute at one-loop order the renormalization of the Gluino-Glue operator and all operator mixing coefficients.
hep-latPoS(2022)·0 citations
07*
Gliding down the QCD transition line, from $N_{f} = 2$ till the onset of conformality
A.Yu. Kotov (Fachhochsch., Julich and Dubna, JINR)🇩🇪 · M.P. Lombardo (INFN, Florence)🇮🇹 · A. Trunin (Samara U.)🇷🇺
We review the hot QCD transition with varying number of flavors, from two till the onset of the conformal window. We discuss the universality class for $N_{f} = 2$ , along the critical line for two massless light flavors, and a third flavor whose mass serves as an interpolator between $N_{f} = 2$ and $N_{f} = 3$ . We identify a possible scaling window for the 3D $O (4)$ universality class transition, and its crossover to a mean field behaviour. We follow the transition from $N_{f} = 3$ to larger $N_{f}$ , when it remains of first order, with an increasing coupling strength; we summarize its known properties, including possible cosmological applications as a model for a strong electroweak transition. The first order transition, and its accompanying second order endpoint, finally morphs into the essential singularity at the onset of the conformal window, following the singular behaviour predicted by the Functional Renormalization Group.
hep-lathep-phhep-thnucl-thSymmetry(2021)·18 citations
08*
Generative learning for the problem of critical slowing down in lattice Gross Neveu model
Ankur Singha🇮🇳 · Dipankar Chakrabarti🇮🇳 · Vipul Arora🇮🇳
In lattice field theory, Monte Carlo simulation algorithms get highly affected by critical slowing down in the critical region, where autocorrelation time increases rapidly. Hence the cost of generation of lattice configurations near the critical region increases sharply. In this paper, we use a Conditional Generative Adversarial Network (C-GAN) for sampling lattice configurations. We train the C-GAN on the dataset consisting of Hybrid Monte Carlo (HMC) samples in regions away from the critical region, i.e., in the regions where the HMC simulation cost is not so high. Then we use the trained C-GAN model to generate independent samples in the critical region. Thus, the overall computational cost is reduced. We test our approach for Gross-Neveu model in 1+1 dimension. We find that the observable distributions obtained from the proposed C-GAN model match with those obtained from HMC simulations, while circumventing the problem of critical slowing down.
hep-latSciPost Phys.Core(2022)·10 citations
09*
Hybrid static potentials in SU(3) lattice gauge theory at small quark-antiquark separations
Carolin Schlosser🇩🇪 · Marc Wagner🇩🇪
We compute the $Π_{u}$ and $Σ_{u}^{-}$ hybrid static potentials in SU(3) lattice gauge theory using four different lattice spacings ranging from $a = 0.040 fm$ to $a = 0.093 fm$ . We provide lattice data points for quark-antiquark separations as small as $0.08 fm$ , where the $a$ -dependent self-energy as well as lattice discretization errors at tree-level of perturbation theory and at leading order in $a^{2}$ have been removed. We also investigate and exclude possibly present systematic errors from topological freezing, due to the finite spatial lattice volume and from glueball decays. Moreover, we provide corresponding parametrizations of the potentials, which can e.g. be used for Born-Oppenheimer predictions of heavy hybrid mesons.
hep-latPRD(2022)·45 citations
10*
Calculation of kaon semileptonic form factor with the PACS10 configuration
Takeshi Yamazaki🇯🇵 · Ken-ichi Ishikawa🇯🇵 · Naruhito Ishizuka🇯🇵 · Yoshinobu Kuramashi🇯🇵 · Yoshifumi Nakamura🇯🇵 · Yusuke Namekawa🇯🇵 · Yusuke Taniguchi🇯🇵 · Naoya Ukita🇯🇵 · Tomoteru Yoshié for PACS Collaboration🇯🇵
We present preliminary results for the kaon semileptonic form factors using the PACS10 configurations, whose physical volume is more than (10 fm) $^{3}$ at the physical point with the lattice spacings of 0.085 and 0.064 fm. The configurations were generated using the Iwasaki gauge action and $N_{f} = 2 + 1$ stout-smeared Clover quark action. For the continuum extrapolation, we calculate the form factors with the local and conserved vector currents. The form factors in the two lattice spacings are extrapolated to the continuum limit using a fit function based on the NLO SU(3) ChPT formula with terms corresponding to finite lattice spacing effects. The value of $∣ V_{u s} ∣$ is determined using our preliminary result of the form factor at the zero momentum transfer in the continuum limit. The result is compared with recent lattice results, and also predictions of the standard model from the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix.
hep-latPoS(2022)·2 citations
11*
Lattice calculation of $χ_{c 0} \to 2 γ$ decay width
Zuoheng Zou🇨🇳 · Yu Meng🇨🇳 · Chuan Liu🇨🇳
We perform a lattice QCD calculation of the $χ_{c 0} \to 2 γ$ decay width using a model-independent method which does not require a momentum extrapolation of the corresponding off-shell form factors. The simulation is performed on ensembles of $N_{f} = 2$ twisted mass lattice QCD gauge configurations with three different lattice spacings. After a continuum extrapolation, the decay width is obtained to be $Γ_{γ γ} (χ_{c 0}) = 3.65 (83)_{stat} (21)_{lat.syst} (66)_{syst} keV$ . Albeit this large statistical error, our result is compatible with the experimental results within 1.3 $σ$ . Potential improvements of the lattice calculation in the future are also discussed.
hep-latCPC(2022)·7 citations
12*
Meson thermal masses at different temperatures
Sergio Chaves García-Mascaraque🇬🇧 · Gert Aarts🇬🇧 · Chris Allton🇬🇧 · Timothy Burns🇬🇧 · Simon Hands🇬🇧 · Benjamin Jäger🇩🇰
We determine the ground state meson masses at low temperature using simulations with $2 + 1$ flavours of improved Wilson-clover fermions. Subsequently we study the effect of increasing the temperature of the hadron gas, including the transition to the quark-gluon plasma, as well as the restoration of $S U (2)_{A}$ chiral symmetry. We use the FASTSUM anisotropic, fixed-scale Generation2L ensembles and consider mesons with light, strange and charm content.
hep-latPoS(2022)·3 citations
13*
Bulk-preventing actions for SU(N) gauge theories
Tobias Rindlisbacher🇨🇭 · Kari Rummukainen🇫🇮 · Ahmed Salami🇫🇮
We introduce a one-parameter family of SU(N) gauge actions which, when used in combination with an HMC update algorithm, prevent the gauge system from entering an artificial bulk-"phase". We briefly discuss the mechanism behind the bulk-prevention and present test results for different SU(N) gauge groups.
hep-latPoS(2022)·1 citation
14*
Symmetric Mass Generation in Lattice Gauge Theory
Nouman Butt🇺🇸 · Simon Catterall🇺🇸 · Goksu Can Toga🇺🇸
We construct a four dimensional lattice gauge theory in which fermions acquire mass without breaking symmetries as a result of gauge interactions. Our model consists of reduced staggered fermions transforming in the bifundamental representation of a $S U (2) \times S U (2)$ gauge symmetry. This fermion representation ensures that single site bilinear mass terms vanish identically. A symmetric four fermion operator is however allowed and we show numerical results that show that a condensate of this operator develops in the vacuum.
hep-lathep-thSymmetry(2021)·25 citations
15*
First study of twist-3 PDFs for the proton from lattice QCD
Shohini Bhattacharya🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Andreas Metz🇺🇸 · Aurora Scapellato🇺🇸 · Fernanda Steffens🇩🇪
In these proceedings, we summarize the main results from the first-ever calculations of the chiral-even and chiral-odd twist-3 parton distributions, $g_{T} (x)$ and $h_{L} (x)$ , of the proton from lattice QCD. We use an $N_{f} = 2 + 1 + 1$ ensemble of maximally twisted mass fermions with a clover improvement. The lattice has a spatial extent of 3~fm, the lattice spacing is 0.093~fm, and the pion mass is $260$ ~MeV. The matrix elements are obtained with a source-sink time separation of 1.12~fm to control contamination from excited states. The calculation is based on the quasi-PDF approach and employs three values for the proton momentum: 0.83~GeV, 1.25~GeV, and 1.67~GeV. The lattice data are renormalized non-perturbatively using the RI $^{'}$ scheme, and the final results are presented in the $MS$ scheme at the scale of 2~GeV. Furthermore, we compute in the same setup the helicity, $g_{1} (x)$ , and transversity, $h_{1} (x)$ , distributions, which are used to compare $g_{T} (x)$ and $h_{L} (x)$ to their Wandzura-Wilczek approximations. For $h_{L} (x)$ , we combine results for the isovector and isoscalar flavor combinations to disentangle the individual up- and down-quark contributions.
hep-latPoS(2022)·5 citations
16*
Connecting Matrix Elements to Multi-Hadron Form-Factors
Andrew W. Jackura🇺🇸
We discuss developments in calculating multi-hadron form-factors and transition processes via lattice QCD. Our primary tools are finite-volume scaling relations, which map spectra and matrix elements to the corresponding multi-hadron infinite-volume amplitudes. We focus on two hadron processes probed by an external current, and provide various checks on the finite-volume formalism in the limiting cases of perturbative interactions and systems forming a bound state. By studying model-independent properties of the infinite-volume amplitudes, we are able to rigorously define form-factors of resonances.
hep-lathep-phnucl-thPoS(2022)·0 citations
17*
$b ˉ c ˉ q_{1} q_{2}$ four-quark states from Lattice QCD
M. Padmanath🇩🇪 · Nilmani Mathur🇮🇳
We present the results of a lattice calculation of four-quark states with the quark contents $b ˉ c ˉ q_{1} q_{2}$ where $q_{1}, q_{2} \in u, d, s$ . For the spin 1 states, when the light quark ( $q_{1}, q_{2}$ ) masses are lighter, we find at least one energy level below the possible elastic threshold energy levels. These calculations are performed on three dynamical $N_{f} = 2 + 1 + 1$ highly improved staggered quark ensembles at lattice spacings of about 0.12, 0.09, and 0.06 fm. We use the overlap action for light to charm quarks while a non-relativistic action with non-perturbatively improved coefficients is employed for the bottom quark.
hep-lathep-exhep-phnucl-thPoS(2022)·17 citations
18*
Quantum thermalization of gauge theories: chaos, turbulence and universality
Niklas Mueller🇺🇸 · Torsten V. Zache🇦🇹 · Robert Ott🇩🇪
In this talk, we discuss real-time thermalization dynamics of $Z_{2}$ Lattice Gauge Theory in 2+1 spacetime dimensions. While classical thermalization is commonly associated with chaotic behavior, turbulence and universality, the manifestation of these phenomena in quantum mechanical systems is not clear. However, when viewed through the lens of Entanglement Structure, we find that quantum thermalization proceeds in characteristic stages and reveals phenomena remarkably similar to their classical counterparts: chaos, turbulence and universality.
hep-lathep-phquant-phPoS(2022)·3 citations
19*
Supersymmetric Gauge Theory on the Graph
Kazutoshi Ohta🇯🇵 · So Matsuura🇯🇵
We consider two-dimensional N=(2,2) supersymmetric gauge theory on discretized Riemann surfaces. We find that the discretized theory can be efficiently described by using graph theory, where the bosonic and fermionic fields are regarded as vectors on a graph and its dual. We first analyze the Abelian theory and identify its spectrum in terms of graph theory. In particular, we show that the fermions have zero modes corresponding to the topology of the graph, which can be understood as kernels of the incidence matrices of the graph and the dual graph. In the continuous theory, a scalar curvature appears as an anomaly in the Ward-Takahashi (WT) identity associated with a U(1) symmetry. We find that the same anomaly arises as the deficit angle at each vertex on the graph. By using the localization method, we show that the path integral on the graph reduces to an integral over a set of the zero modes. The partition function is then ill-defined unless suitable operators are inserted. We extend the same argument to the non-Abelian theory and show that the path integral reduces to multiple integrals of Abelian theories at the localization fixed points.
↳ hep-thhep-latPTEP(2022)·8 citations
20*
One-loop structure of parton distribution for the gluon condensate and "zero modes"
Anatoly Radyushkin🇺🇸 · Shuai Zhao🇺🇸
We present results for one-loop corrections to the recently introduced "gluon condensate" PDF $F (x)$ . In particular, we give expression for the $g g$ -part of its evolution kernel. To enforce strict compliance with the gauge invariance requirements, we have used on-shell states for external gluons, and have obtained identical results both in Feynman and light-cone gauges. No "zero mode" $δ (x)$ terms were found for the twist-4 gluon PDF $F (x)$ . However a $q^{2} δ (x)$ term was found for the $ξ = 0$ GPD $F (x, q^{2})$ at nonzero momentum transfer $q$ . Overall, our results do not agree with the original attempt of one-loop calculations of $F (x)$ for gluon states, which sets alarm warning for calculations that use matrix elements with virtual external gluons and for lattice renormalization procedures based on their results.
↳ hep-phhep-latJHEP(2021)·7 citations
21*
Confinement and Pseudoscalar Glueball Spectrum from Anisotropic Non-susy D $2$ Brane under Hawking-Page transition
Adrita Chakraborty🇮🇳 · Kuntal Nayek🇮🇳
Here we analyse the low energy confining phase of the $2 + 1$ dimensional quenched QCD-like theory in anisotropic non-supersymmetric D $2$ brane background with the holographic approach. Two key features of QCD -- flux-tube tension and mass spectrum of pseudoscalar glueball are studied. The non-supersymmetric D $2$ branes with anisotropy in time direction are considered as the gravity theory. Tuning the anisotropic parameter, we get the Hawking-Page transition in the gravity background. On the dual theory, this refers the confinement-deconfinement phase transition. Using the Wilson loop, the linear confinement at this regime is effectively confirmed by calculating the flux tube tension $σ$ from the Nambu-Goto action of a test string with its endpoints located at the boundary. In the next part, we have illustrated numerically the mass spectrum $M_{0^{-+}}$ of the pseudoscalar glueball states. We have found, at the transition point, that the glueball mass becomes trivially small. Finally we relate the anisotropy parameter with the temperature and show the variation of the glueball mass at various temperature. Using the Lattice QCD data of $σ$ , it is found that $M_{0^{-+}} = 2.3$ GeV and $M_{0^{-+}}^{*} = 3.8$ GeV at $T = 0$ whereas $M_{0^{-+}} = 0.9$ GeV and $M_{0^{-+}}^{*} = 1.1$ GeV at $T = T_{c}$ .
↳ hep-thhep-lathep-ph0 citations
22*
Determination of the spectroscopic parameters of beauty-partners of $T_{cc}$ from QCD
T.M.Aliev🇹🇷 · S.Bilmis🇹🇷 · M.Savci🇹🇷
Motivated by the recent discovery of a new tetra-quark $T_{cc}^{+}$ state with two charm quarks and two light quarks by LHCb collaboration, we calculate the spectroscopic parameters, namely, the mass and residues of beauty partners of $T_{cc}^{+}$ within QCD sum rules by using hadronic molecular $B B^{*}$ picture. The obtained results are compared with the predictions of different approaches in the literature.
↳ hep-phhep-exhep-latPRD(2022)·11 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.