arXiv: High Energy Physics - Lattice最新文献_第3页

Sign Problems in Quantum Field Theory: Classical and Quantum Approaches 量子场论中的符号问题:经典和量子方法

arXiv: High Energy Physics - Lattice Pub Date : 2020-06-05 DOI: 10.13016/U5EG-X7Y6

S. Lawrence

{"title":"Sign Problems in Quantum Field Theory: Classical and Quantum Approaches","authors":"S. Lawrence","doi":"10.13016/U5EG-X7Y6","DOIUrl":"https://doi.org/10.13016/U5EG-X7Y6","url":null,"abstract":"Monte Carlo calculations in the framework of lattice field theory provide non-perturbative access to the equilibrium physics of quantum fields. When applied to certain fermionic systems, or to the calculation of out-of-equilibrium physics, these methods encounter the so-called sign problem, and computational resource requirements become impractically large. These difficulties prevent the calculation from first principles of the equation of state of quantum chromodynamics, as well as the computation of transport coefficients in quantum field theories, among other things. \u0000This thesis details two methods for mitigating or avoiding the sign problem. First, via the complexification of the field variables and the application of Cauchy's integral theorem, the difficulty of the sign problem can be changed. This requires searching for a suitable contour of integration. Several methods of finding such a contour are discussed, as well as the procedure for integrating on it. Two notable examples are highlighted: in one case, a contour exists which entirely removes the sign problem, and in another, there is provably no contour available to improve the sign problem by more than a (parametrically) small amount. \u0000As an alternative, physical simulations can be performed with the aid of a quantum computer. The formal elements underlying a quantum computation - that is, a Hilbert space, unitary operators acting on it, and Hermitian observables to be measured - can be matched to those of a quantum field theory. In this way an error-corrected quantum computer may be made to serve as a well controlled laboratory. Precise algorithms for this task are presented, specifically in the context of quantum chromodynamics.","PeriodicalId":8440,"journal":{"name":"arXiv: High Energy Physics - Lattice","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87259673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

S-wave kaon–nucleon potentials with all-to-all propagators in the HAL QCD method HAL QCD方法中具有全对全传播子的s波k -核子势

arXiv: High Energy Physics - Lattice Pub Date : 2020-06-02 DOI: 10.1093/PTEP/PTAA118

K. Murakami, Yutaro Akahoshi, S. Aoki

{"title":"S-wave kaon–nucleon potentials with all-to-all propagators in the HAL QCD method","authors":"K. Murakami, Yutaro Akahoshi, S. Aoki","doi":"10.1093/PTEP/PTAA118","DOIUrl":"https://doi.org/10.1093/PTEP/PTAA118","url":null,"abstract":"In this paper, employing an all-to-all quark propagator technique, we investigate the kaon-nucleon interactions in lattice QCD. We calculate the S-wave kaon-nucleon potentials at the leading order in the derivative expansion in the time-dependent HAL QCD method, using (2+1)-flavor gauge configurations at the lattice spacing $a approx 0.09$ fm on $32^3 times 64$ lattices and the pion mass $m_{pi} approx 570$ MeV. We take the one-end trick for all-to-all propagators, which allows us to put the zero momentum hadron operators at both source and sink and to smear quark operators at the source. We find the stronger repulsive interaction in the $I=1$ channel than in the $I=0$. The phase shifts obtained by solving the Schrodinger equations with the potentials qualitatively reproduce the energy dependence of the experimental phase shifts, and have the similar behavior to the previous results from lattice QCD without all-to-all propagators. Our study demonstrates that the all-to-all quark propagator technique with the one-end trick is useful to study interactions for meson-baryon systems in the HAL QCD method, so that we will apply it to meson-baryon systems which contain quark-antiquark creation/annihilation processes in our future studies.","PeriodicalId":8440,"journal":{"name":"arXiv: High Energy Physics - Lattice","volume":"118 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74869618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

New perspectives on the emergence of (3+1)D expanding space-time in the Lorentzian type IIB matrix model 洛伦兹IIB型矩阵模型中(3+1)D扩展时空出现的新视角

arXiv: High Energy Physics - Lattice Pub Date : 2020-06-01 DOI: 10.22323/1.376.0178

J. Nishimura

引用次数: 10

Gluon field digitization via group space decimation for quantum computers 基于群空间抽取的量子计算机胶子场数字化

arXiv: High Energy Physics - Lattice Pub Date : 2020-05-28 DOI: 10.1103/physrevd.102.114513

Yao Ji, Henry Lamm, Shuchen Zhu

引用次数: 40

Isovector parton distribution functions of the proton on a superfine lattice 质子在超细晶格上的等矢量部子分布函数

arXiv: High Energy Physics - Lattice Pub Date : 2020-05-25 DOI: 10.1103/PHYSREVD.102.074504

Z. Fan, Xiang Gao, Rui-Cheng Li, Huey-Wen Lin, Nikhil Karthik, S. Mukherjee, P. Petreczky, S. Syritsyn, Yi-Bo Yang, Rui Zhang

引用次数: 16

Topology and axions in QCD QCD 中的拓扑和轴子

arXiv: High Energy Physics - Lattice Pub Date : 2020-05-13 DOI: 10.1142/S0217751X20300100

M. Lombardo, A. Trunin

引用次数: 26

From String Breaking to Quarkonium Spectrum 从断弦到夸克谱

arXiv: High Energy Physics - Lattice Pub Date : 2020-05-12 DOI: 10.5506/aphyspolbsupp.14.93

M. Catillo, M. K. Marinkovi'c, P. Bicudo, N. Cardoso

引用次数: 0

Nf=2+1 QCD thermodynamics with gradient flow using two-loop matching coefficients Nf=2+1采用双环匹配系数的梯度流动QCD热力学

arXiv: High Energy Physics - Lattice Pub Date : 2020-05-01 DOI: 10.1103/physrevd.102.014510

Y. Taniguchi, S. Ejiri, K. Kanaya, M. Kitazawa, Hiroshi Suzuki, T. Umeda

{"title":"Nf=2+1\u0000 QCD thermodynamics with gradient flow using two-loop matching coefficients","authors":"Y. Taniguchi, S. Ejiri, K. Kanaya, M. Kitazawa, Hiroshi Suzuki, T. Umeda","doi":"10.1103/physrevd.102.014510","DOIUrl":"https://doi.org/10.1103/physrevd.102.014510","url":null,"abstract":"We study thermodynamic properties of Nf=2+1 QCD on the lattice adopting O(a)-improved Wilson quark action and Iwasaki gauge action. To cope with the problems due to explicit violation of the Poincare and chiral symmetries, we apply the Small Flow-time eXpansion (SFtX) method based on the gradient flow, which is a general method to correctly calculate any renormalized observables on the lattice. In this method, the matching coefficients in front of operators in the small flow-time expansion are calculated by perturbation theory. In a previous study using one-loop matching coefficients, we found that the SFtX method works well for the equation of state, chiral condensates and susceptibilities. In this paper, we study the effect of two-loop matching coefficients by Harlander et al. We also test the influence of the renormalization scale in the SFtX method. We find that, by adopting the mu_0 renormalization scale of Harlander et al. instead of the conventional mu_d=1/sqrt{8t} scale, the linear behavior at large t is improved so that we can perform the t -> 0 extrapolation of the SFtX method more confidently. In the calculation of the two-loop matching coefficients by Harlander et al., the equation of motion for quark fields was used. For the entropy density in which the equation of motion has no effects, we find that the results using the two-loop coefficients agree well with those using one-loop coefficients. On the other hand, for the trace anomaly which is affected by the equation of motion, we find discrepancies between the one- and two-loop results at high temperatures. By comparing the results of one-loop coefficients with and without using the equation of motion, the main origin of the discrepancies is suggested to be attributed to O((aT)^2)=O(1/N_t^2) discretization errors in the equation of motion at N_t =< 10.","PeriodicalId":8440,"journal":{"name":"arXiv: High Energy Physics - Lattice","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76384765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15

Insights on proton structure from lattice QCD: The twist-3 parton distribution function gT(x) 晶格QCD对质子结构的启示:扭转-3部子分布函数gT(x)

arXiv: High Energy Physics - Lattice Pub Date : 2020-04-08 DOI: 10.1103/physrevd.102.111501

S. Bhattacharya, K. Cichy, M. Constantinou, A. Metz, Aurora Scapellato, F. Steffens

{"title":"Insights on proton structure from lattice QCD: The twist-3 parton distribution function \u0000gT(x)","authors":"S. Bhattacharya, K. Cichy, M. Constantinou, A. Metz, Aurora Scapellato, F. Steffens","doi":"10.1103/physrevd.102.111501","DOIUrl":"https://doi.org/10.1103/physrevd.102.111501","url":null,"abstract":"In this work, we present the first-ever calculation of the isovector flavor combination of the twist-3 parton distribution function $g_T(x)$ for the proton from lattice QCD. We use an ensemble of gauge configurations with two degenerate light, a strange and a charm quark ($N_f=2+1+1$) of maximally twisted mass fermions with a clover improvement. The lattice has a spatial extent of 3 fm, lattice spacing of 0.093 fm, and reproduces a pion mass of $260$ MeV. We use the quasi-distribution approach and employ three values of the proton momentum boost, 0.83 GeV, 1.25 GeV and 1.67 GeV. We use a source-sink separation of 1.12 fm to suppress excited-states contamination. The lattice data are renormalized non-perturbatively. We calculate the appropriate matching within Large Momentum Effective Theory, which is applied to the lattice data in order to obtain $g_T$. The final distribution is presented in the $overline{rm MS}$ scheme at a scale of 2 GeV. We also calculate the helicity distribution $g_1$ to test the Wandzura-Wilczek approximation for $g_T$. We find that the approximation works well for a large range in $x$. \u0000This work demonstrates the feasibility of accessing twist-3 parton distribution functions from novel methods within lattice QCD, and can provide important insights on the structure of hadrons.","PeriodicalId":8440,"journal":{"name":"arXiv: High Energy Physics - Lattice","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75565084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 21

Trace anomaly and dynamical quark mass 痕迹异常与动态夸克质量

arXiv: High Energy Physics - Lattice Pub Date : 2020-03-29 DOI: 10.22323/1.363.0001

Yi-Bo Yang, Jian Liang, Zhaofeng Liu, P. Sun

引用次数: 1