A variation of the Domain Wall operator with an additional parameter α will be introduced. The conditioning of the new Domain Wall operator depends on α, whereas the corresponding 4D propagator does not. The new and the conventional Domain Wall operator agree for α = 1. By tuning α, speed ups of the linear system solvers of around 20% could be achieved.
I summarize recent work (arXiv:2003.10974) providing a generalization of finite-volume scattering formalism for non-identical pions in isosymmetric QCD. The result allows one to use discrete finite-volume energies, determined using lattice QCD, to constrain scattering amplitudes for all possible values of two- and three-pion isospin. As an example, I present a toy implementation for I(πππ) =...
Composite Higgs models must exhibit very different dynamics from quantum chromodynamics (QCD) regardless whether they describe the Higgs boson as a dilaton-like state or a pseudo-Nambu-Goldstone boson. Large separation of scales and large anomalous dimensions are frequently desired by phenomenological models. Mass-split systems are well-suited for composite Higgs models because they are...
The thermal transition in QCD has been studied in detail using the staggered-quark formulation. Here we report on progress using Nf=2+1 flavours of Wilson fermions, employing anisotropic, fixed-scale lattice simulations. Observables are compared for two values of the pion mass, focusing on chiral properties: the chiral condensate and its susceptibility, quark number susceptibilities, and the...
We present a simplified derivation of the relativistic three-particle quantization condition for identical, spinless particles. The simplification is afforded by using time-ordered perturbation theory (TOPT) and a three-particle quasilocal K matrix that is not fully symmetrized to organize the relevant diagrams in an intuitive manner, ultimately leading to a new form of the quantization...
We present a lattice QCD based determination of the chiral phase transition temperature in QCD with two massless (up and down) and one strange quark having its physical mass. We propose and calculate two novel estimators for the chiral transition temperature for several values of the light quark masses, corresponding to Goldstone pion masses in the range between (approximately) 58 MeV and...
Near-conformal systems are favored candidates to describe composite Higgs or composite dark matter particles. Their finite temperature phase structure may provide new insights into the dynamics. It is particularly important to determine the order of the phase transition. Many-flavor near-conformal systems might exhibit a first-order phase transition with a possibly large latent heat. This...
We compare two of different methods for coarsening domain wall fermions and discuss progress towards a multigrid method for DWF with the ability to set up and solve during gauge configuration generation.
With non-perturbative lattice calculations we investigate the finite-temperature confinement transition of a composite dark matter model. We focus on the regime in which this early-universe transition is first order and would generate a stochastic background of gravitational waves. Future searches for stochastic gravitational waves will provide a new way to discover or constrain composite dark...
We will present results on the Dirac eigenvalue spectrum as well as its relation to the axial U(1) and SU(2)xSU(2) symmetries at a high temperature in (2+1)-flavor QCD. The simulations are carried out using the highly improved staggered quarks (HISQ) action on Nτ = 8, 12 and 16 lattices with the aspect ratio Nσ /Nτ in a range of [4,9] and 4-5 pion masses ranging from 160 MeV to 55 MeV at a...
We show that a recently derived alternative form of the relativistic three-particle quantization condition for identical particles can be rewritten in terms of the R matrix introduced to give a unitary representation of the infinite-volume three-particle scattering amplitude. Combined with earlier work, this shows the equivalence of the relativistic effective field theory approach of Refs. [1,...
We present a multiple right-hand side (rhs) implementation of the Adaptive Aggregation-based Domain Decomposition Multigrid method (DD$\alpha$AMG) using twisted mass fermions.
Our implementation extends the strong scaling region of DD$\alpha$AMG and simplifies vectorization, which would otherwise require using vector extensions. This multiple rhs implementation is thus better suited to take...
Hamiltonian effective field theory (HEFT) is an approach which allows for the extraction of hadron finite-volume energy spectra from scattering observables such as phase shifts and inelasticities. As an alternative to Luscher's method, HEFT easily generalises to systems with multiple coupled channels and multiple bare states. HEFT also allows for the extraction of eigenvectors from the...
Chirality of HYP-smeared staggered quarks and its matrix elements on Dirac eigenspace are studied. We introduce a new chirality operator and a new shift operator, and show that chiral Ward identities relate them. Leakage is defined as matrix elements between two eigenstates of the staggered Dirac operator, which represents the transition matrix from one eigenstate to the other. Numerical...
We report our recent extension of Bridge++, a general-purpose code set for numerical simulations of lattice gauge theories, to the latest vector processor, NEC SX-Aurora TSUBASA. The Bridge++ project aims at developing a readable, extensible, and portable workbench with sufficiently high performance. Based on the code set we investigate fast algorithms for parallel numerical calculations, and...
We propose new way of heavy ion collisions experiment data analysis. We analyze physical parameters of fireball created in RHIC experiment based on Grand Canonical Distribution and different Lattice QCD data available at the moment. Our results on chemical potential are in agreement with previous model estimations and do not depend on Lattice setup. At same time, we found possible T(V) states...
The chiral symmetry restoration of QCD, with two light flavours in the chiral limit, is expected to be a phase transition belonging to the universality class of 3d O(N) models. The imprint of the criticality should be observed in the thermodynamic observables if we move close enough to the chiral limit. We discuss results of conserved charge fluctuations and Polyakov loop, which we propose to...
QPACE 4 is the latest member of the QCD PArallel Compute Engine (QPACE) series, which was deployed in Regensburg in June 2020. It features 64 Fujitsu A64FX model FX700 CPUs interconnected by InfiniBand EDR. The A64FX is the first CPU supporting the Arm Scalable Vector Extension (SVE). In this contribution we discuss the implementation of SVE in the Grid Lattice QCD framework and show Grid...
We study chirality of staggered quarks on the Dirac eigenvalue spectrum using machine learning technique. As a result of theoretical research, we expect a characteristic pattern, we call leakage pattern, in the matrix elements of the chirality operator sandwiched between two eigenstates of staggered Dirac operator. Machine learning analysis gives 98.7(34)% accuracy per a single normal gauge...
In this talk, we show the recent status of the rho resonance study in the HAL QCD method.
We investigate the I=1 two-pion potential at $m_{\pi} \approx 411$ MeV by using a new calculation strategy, namely the combination of three techniques: the one-end trick, the sequential propagator, and covariant approximation averaging (CAA).
Thanks to the new strategy, we determine the non-local I=1...
Hadronic matter is known to change its behaviour during a crossover at finite temperature. One part of this crossover is the chiral transition, whose properties are well studied. The other part involves the fate of hadronic bound states and single quarks, the transition of which is less clear. We study two-flavor QCD for temperatures starting from 190 MeV and quark masses down to...
The origin of the low-lying nature of the Roper resonance has been the subject of significant interest for many years, including several investigations using lattice QCD. It has been claimed that chiral symmetry plays an important role in our understanding of this resonance. We present results from our systematic examination of the potential role of chiral symmetry in the low-lying nucleon...
Layered systems such as graphene have become an important area of investigation. Within the broader programme of investigating critical phenomena in such systems, we look at different mass configurations for domain wall fermions and overlap fermions in 2+1D. The equivalence between formulations is reviewed, and formulations for the condensate and susceptibility are given. Locality of fermion...
The supercomputer Fugaku is a new supercomputer in Kobe, Japan, co-developed by RIKEN with Fujitsu, and the top system of the latest June 2020 TOP500 supercomputers. I will introduce the supercomputer Fugaku and a Lattcie QCD simulation library, QCD Wide SIMD library (QWS) for Fugaku. I will also present some tuning methods for Fugaku, QWS performance on Fugaku, and tentative benchmark results...
We study I = 0 quarkonium resonances decaying into pairs of heavy-light mesons using static-static-light-light potentials from lattice QCD. To this end, we solve a coupled channel Schrödinger equation with one confined quarkonium channel and two channels with a heavy-light meson pair to compute phase shifts and t-matrix poles for the lightest decay channel. Finally, we discuss our results in...
A correct non perturbative treatment of gauge theories requires physical particles to be described by gauge invariant operators. It is then appropriate to use composite operators made of elementary gauge dependant fields as physical observables.
We will present results on the second order fluctuations of net baryon number, electric charge and strangeness as well as correlations among these conserved charges in (2+1)-flavor lattice QCD in the presence of a background magnetic field.
Simulations are performed using the tree level improved gauge action and the highly improved staggered quark
(HISQ) action with a fixed scale approach...
As parallel systems become massive, the neighboring communication in lattice QCD becomes more and more important.
In this talk, I will focus on the implementation of neighboring communication in QCD Wide SIMD library (QWS) for the supercomputer Fugaku.
We adopt the double buffering algorithm and implement it on top of a wrapper library to call the uTofu API, which is a low level interface...
We study the pressure anisotropy in anisotropic finite-size systems in SU(3) Yang-Mills theory at nonzero temperature. Lattice simulations are performed on lattices with anisotropic spatial volumes with periodic boundary conditions. The energy-momentum tensor defined through the gradient flow is used for the analysis of the stress tensor on the lattice. We find that a clear finite-size effect...
We present the first lattice calculation of the scattering amplitude of Goldstone bosons in the singlet channel relevant to test the viability of a composite Higgs scenario beyond the Standard Model. In such a framework, the scattering of the underlying Goldstone bosons controls the properties of the Higgs boson. The Higgs boson properties are constrained by the Standard Model and...
We investigate meson-baryon interactions in the HAL QCD method with all-to-all propagators using the stochastic estimations. We mainly report the analysis of the S-wave kaon-nucleon interactions at $m_{\pi} \approx 570$ MeV. Since there are no quark-antiquark creation/annihilation processes in this system, all-to-all propagators merely play a role in increasing statistics. In addition, we...
Lattice QCD is one of the major scientific work-loads on supercomputer installations. Most of the computer time is spent in an iterative solver of a large, sparse set of linear equations. One of the simplest examples of such an iterative solver is the conjugate gradient algorithm. In this talk, we present an optimized implementation of this algorithm in the context of Lattice QCD for Xilinx...
Using complex Langevin dynamics, we probe the possibility of dynamical breaking of supersymmetry in a class of low-dimensional N=2 supersymmetric quantum field theories with complex potentials. We conclude that complex Langevin dynamics can reliably predict the nonperturbative breaking of supersymmetry in cases where Monte Carlo methods are unreliable.
The most computational cost in typical lattice QCD simulation is doing the invertion to obtain the propagator. While it is a huge waste to free the propagators in RAM after the contraction. This work explores a field selection algorithm for the correlation functions. The field selection algorithm constructs the correlation function by selecting point on the lattice. It is found that almost the...
In this report we present our first results on lattice study of QCD equation of state in external magnetic field and at finite baryon density. The simulations are performed with $N_f = 2+1$ rooted staggered quarks at physical quark masses. Finite baryon density is implemented through the lattice simulations at imaginary chemical potential. The results for the equation of state are expanded in...
We explore the quark composition of bottomonium bound states and resonances with I = 0 and L = 0 using lattice QCD static potentials from a previous study of string breaking and the Born-Oppenheimer approximation. We also compare the relative importance of meson-meson and diquark-antidiquark creation operators for the lattice QCD static potential relevant for b-bar b-bar u d tetraquarks with I = 0.
We report our estimation for the Isgur-Wise form factors for the inclusive semileptonic $B \to X_c \ell\nu$ on 2+1-flavor lattice QCD.
The M\"obius domain-wall fermion action is used for light, strange, charm and bottom quarks. The structure function receives contributions from various exclusive modes, including the dominant S-wave states $D^{(*)}_s$ as well as the P-wave states $D_s^{**}$....
We report the progress in the lattice studies of Sp(4) gauge theory coupled to fermions in the antisymmetric representation. Such a theory containing three Dirac flavors has a direct relevance to the phenomenological model building for certain types of composite Higgs and top partial compositeness. We formulate the lattice action with the standard plaquette and the Wilson-Dirac fermions. Our...
The chiral susceptibility, or the first derivative of the chiral condensate, is used as a probe for QCD phase transition. It is well-known that the chiral condensate is an order parameter of SU(2)_L x SU(2)_R symmetry breaking. However, the condensate also breaks the axial U(1) symmetry, which is usually not paid attention as it is already broken by anomaly. In this talk, we would like to show...
The IKKT matrix model is a promising candidate for a nonperturbative formulation of superstring theory, in which spacetime is conjectured to emerge dynamically from the microscopic matrix degrees of freedom in the large-N limit. Indeed in the Lorentzian version, Monte Carlo studies suggested the emergence of (3+1)-dimensional expanding space-time. Here we study the Euclidean version instead,...
We present the first realistic lattice QCD calculation of the γW-box diagrams relevant for beta decays. The nonperturbative low-momentum integral of the γW loop is calculated using a lattice QCD simulation, complemented by the perturbative QCD result at high momenta. Using the pion semileptonic decay as an example, we demonstrate the feasibility of the method. By using domain wall fermions at...
There exists a long standing discrepancy of around 3.5 sigma between experimental measurements and standard model calculations of the magnetic moment of the muon. Current experiments aim to reduce the experimental uncertainty by a factor of 4, and Standard Model calculations must also be improved by a similar order. The largest uncertainty in the Standard Model calculation comes from the QCD...
We present an update on our previous studies [1] of pure U(1) lattice gauge theory with a sign problem due to a complex coupling \beta. To that end a novel simulation method is employed:
Configuration space is rewritten as a union of linear submanifolds in complexified space. These submanifolds are the tangent spaces of the Lefschetz thimble decomposition. Therefore the sign problem is...
Monte Carlo simulation of gauge theories with a theta term is known to be extremely difficult due to the sign problem. We consider the complex Langevin method (CLM), which is one of the approaches to overcome this problem. As a first step, we apply the method to 2D U(1) gauge theory with a theta term, which can be solved analytically. We find that naive implementation of the method fails...
Understanding the tension between the Standard Model prediction and the experimental results on the anomalous magnetic moment of the muon (a_\mu) has been an active research field over the past two decades. The theoretical uncertainty mainly comes from the hadronic contributions, among which the hadronic light-by-light scattering ($a_\mu^{hlbl}$) process plays an important role. We investigate...
Neutrinoless double beta decay, if detected, would prove that neutrinos are Majorana fermions and provide the direct evidence for lepton number violation. If such decay would exist in nature, then π−π− → ee and π− → π+ee (or equivalently π−e+ → π+e−) are the two simplest processes accessible via first-principle lattice QCD calculations. In this work, we calculate the long-distance...
The type IIB matrix model was proposed as a nonperturbative formulation of superstring theory. In particular, interesting results such as the emergence of (3+1)D exponentially expanding space-time have been obtained from the Lorentzian version of the model. Recently the complex Langevin simulation of the bosonic model has been performed to avoid the previously used approximation in overcoming...
In a recent work, we describe and quantify a method for setting up a lattice for quantum field theory in AdS2 based on the triangle group, which enables maximally symmetric tilings of hyperbolic space. Here we extend this lattice setup to the AdS3 cylinder via Hamiltonian methods, enabling us to study dynamical systems. We verify basic properties of this discretized Euclidean AdS3 space with...
The Monte Carlo simulation of the gauge theory with a theta term is difficult due to the sign problem. We use the complex Langevin method to overcome the problem. In our previous work on two-dimensional U(1) gauge theory with a theta term, we were able to reproduce the exact solution by introducing a puncture on the torus. We also proved that the effect of the puncture disappears in the...
The leading finite-volume corrections to the HVP contribution to the muonic (g-2) are related to the forward Compton amplitude of the pion in a completely model-independent fashion. The developed formalism is able to capture a few leading contributions, up to errors of order exp(-wML) where w~1.93 and M is the pion mass. By using models and chiPT for the forward Compton tensor, the...
In this talk I will briefly review our recent lattice calculations for matrix elements contributing to the mass and width differences of neutral $B$ mesons [arXiv:1907.01025, arXiv:1910.00970]. The calculations were done using the MILC ensembles generated with 4-flavours of sea quarks utilizing the highly improved staggered quark action. An improved nonrelativistic quark action was used for...
We are presenting our ongoing Lattice QCD study on $B-\bar{B}$ mixing. Comparing a variety of different methods, we are extracting bag parameters $B_{B_{s}}$ and $B_{B_{d}}$ on several RBC/UKQCD and JLQCD ensembles with 2+1 dynamical-flavour domain wall fermions, including physical-pion-mass ensembles. We are simulating a range of heavy quark masses on each ensemble from below the charm quark...
We explore the phase diagram of the 2+1-dimensional Gross-Neveu model in the limit of infinite flavors, which shares certain properties with QCD, and the existence of an inhomogeneous phase using lattice field theory. Numerical results are presented, which include the phase boundaries in the $\mu$-$T$ plane as well as the structure of the chiral condensate in the inhomogeneous phase.
We use a method to calculate the hadron's charge radius without model-dependent momentum extrapolations. The method does not require the additional quark propagator inversions on the twisted boundary conditions or the computation of the momentum derivatives of quark propagators and thus is easy to implement. We apply this method to the calculation of pion charge radius ⟨r^2⟩. For comparison,...
The Lorentzian type IIB matrix model is a promising candidate for a non-perturbative formulation of superstring theory. In the previous work, Monte Carlo calculations provided interesting results indicating the spontaneous breaking of SO(9) to SO(3) and the emergence of (3+1)-dimensional space-time. There, an approximation was used to avoid the sign problem, however. In this talk, we report...
The 't Hooft limit of QCD, also referred to as large Nc limit, constitutes a simplification of the theory that preserves most of its non-perturbative properties, including confinement and spontaneous chiral symmetry breaking. It also leads to some definite predictions such as a non-existing Delta I=1/2 rule in the K-> pi pi isospin decay amplitudes. Many phenomenological approaches to hadron...
For the first time the openQD code was used to generate fully dynamical Nf=1+2+1 QCD+QED configurations with C boundary conditions and degenerate down and strange quarks at an unphysical value of the electromagnetic coupling alpha~0.04. In this talk, technical details about the generation, will be presented. In particular the stability of the algorithm, diagnostic observables and neutral and...
We provide evidence for partial deconfinement by using lattice Monte Carlo simulations of some bosonic matrix models.
Partial deconfinement is the phenomenon that coexists the confined and deconfined phases in the system, in particular of several large-N gauge theories, at finite temperature.
By appropriately fixing the gauge, we observe that only submatrices deconfine in the analysis of the...
The Casimir effect is a quantum phenomenon rooted in the fact that vacuum fluctuations of quantum fields are affected by physical objects and boundaries. As the energy spectrum of vacuum fluctuations depends on distances between (and geometries of) physical bodies, the quantum vacuum exerts a small but experimentally detectable force on neutral objects. Usually, the associated Casimir energy...
We will present the current status of nucleon structure studies with physical light quarks (m_pi = 135 MeV) in a large spatial extent of about 10 fm. Our calculations are carried out with the PACS10 gauge configurations generated by the PACS Collaboration with the stout-smeared O(a) improved Wilson fermions and Iwasaki gauge action at beta=1.82 corresponding to the lattice spacing of 0.084 fm....
We present our results for the semileptonic formfactors of exclusive $B_s \to K \ell \nu$ and $B_s \to D_s \ell \nu$ decays. The calculation is based on RBC/UKQCD's set of 2+1 dynamical flavour gauge field ensembles spanning three lattice spacings. We use domain wall fermions for the valence up/down, strange and charm quarks whilst the bottom quark is simulated using the relativistic heavy...
Tempered Lefschetz thimble method (TLTM) [Fukuma-Umeda(1703.00861)] is an algorithm towards solving the numerical sign problem. There, the integration region is deformed into the complex space following the antiholomorphic gradient flow equation, and the system is parallel-tempered using the flow time as a tempering parameter so as to solve both sign and ergodicity problems simultaneously. In...
Monte Carlo simulations of finite density QCD is plagued by the sign problem. The tempered Lefschetz thimble method (TLTM) [Fukuma-Umeda(1703.00861)] is a promising algorithm towards solving the sign problem, where the integration region is deformed into the complex space and the system is parallel-tempered with the flow time so as to solve both sign and ergodicity problems simultaneously. In...
We present our (HPQCD) latest lattice QCD calculation of the scalar and the vector form factors for the D → Klν semi-leptonic decay over a full range of q^2 including q^2 = 0. This calculation has been performed on the N_f=2+1+1 MILC HISQ ensembles with the physical and heavier than physical light quark masses.This calculation allows us to precisely determine the central CKM matrix element,...
The hadronic form factors at large momentum transfers often suffer from substantial excited state contributions and poor signal-to-noise ratios. Using the Feynman-Hellmann theorem allows for calculations of the hadronic form factors which only rely on two-point functions this allows access to higher momenta while still controlling the excited state contributions. We will present results from...
We report on our calculation of the B->D(*)\ell\nu form factors in 2+1 flavor relativistic lattice QCD. Our simulations are carried out by employing the M\""obius domain-wall quark action at lattice cut-offs a^{-1} \sim 2.4, 3.6 and 4.5 GeV with the bottom quark masses up to 0.7 a^{-1}. We discuss the extrapolation of the form factors to the continuum limit and physical quark masses.
Statistical modeling plays a key role in lattice field theory calculations. Examples including extracting masses from correlation functions or taking the chiral-continuum limit of a matrix element. We discuss the method of model averaging, a way to account for uncertainty due to model variations, from the perspective of Bayesian statistics. Statistical formulas are derived for model-averaged...
In this talk we present the first lattice QCD calculation of unpolarized and helicity generalized parton distributions (GPDs) for the proton. We use the quasi-distribution approach, which relies on computations of correlation functions that, for sufficiently fast moving hadrons, can be matched to light-cone distributions using perturbation theory. The calculations are...
We present the results of HPQCD's recent calculation of the $B_c \rightarrow J/\psi$ semileptonic form factors and $R(J/\psi)$ for the first time from lattice QCD using the heavy-HISQ method. We also extend these results to angular observables which we compute in the standard model and in several new physics scenarios.
We present a synergistic approach between machine learning and histogram reweighting to discover and study phase transitions in physical systems. We treat the output of a neural network, designed for phase classification, as an observable in a statistical system enabling its extrapolation over continuous ranges in parameter space using histogram reweighting. The approach, which leads to...
We will present the first calculation of the nucleon vector and axial-vector charges with a single 2+1+1 flavors Highly Improved Staggered Quarks (HISQ) ensemble generated by the MILC collaboration and a matching valence action. We will focus on the theoretical foundation of staggered baryons and outline the methods to calculate physical observables with staggered valence quarks.
"D → Klν and B → Kl + l − are important heavy to strange semileptonic decay processes, giving us direct comparison with experiment, and access to CKM
matrix elements and potential new physics. We can calculate form factors for
both of these processes in lattice QCD and connect them together by determining heavy to strange form factors for heavy quark masses ranging from c to b. We can also...
Current status of LHP+RBC joint nucleon structure calculations using RBC+UKQCD 2+1-flavor domain-wall fermions lattice-QCD ensembles is summarized.
The quantum link Hamiltonian was introduced two decades ago as an alternative to Wilson’s Euclidean lattice QCD with gauge fields represented by bi-linearfermion/anti-fermion operators, and later generalized as D-theory. Recasting as a Hamiltonian in Minkowski space for real time evolution, D-theory leads naturally to quantum algorithms. We investigate the simplest toy model of U(1) compact...
We extract structure functions corresponding to the first moment of the gluon GPDs from the matrix elements of the gluon energy momentum tensor on a clover ensemble with m_{\pi} = 450 MeV. We present the various GFFs for states of different spins with a focus on the D-terms. We then compare extracted physical quantities like the pressure and shear forces between the different hadrons.
The desire for additional determinations of the CKM matrix element $V_{ub}$ and a long-standing 2-3$\sigma$ discrepancy between results from inclusive $B\to X_u$ and exclusive $B\to\pi$ processes motivate the study of $B\to\pi$ semileptonic form factors on the lattice. The status of our preliminary $B\to\pi\ell\nu$ results will be discussed by highlighting updates to our analysis. The analysis...
Due to the existence of sign problem in the Lattice QCD simulation with finite chemical potential, the traditional Monte-Carlo simulations on classical supercomputers are confronted with significant difficulties on achieving high precision. On the other hand, with the fast development of quantum computers, it might be possible to provide the ultimate solution to sign problem in the future....
We have recently performed a determination of the charm quark mass on Nf = 2+1 CLS ensembles of non-perturbatively improved Wilson fermions. I will present the preliminary results of this analysis for the renormalization-group invariant charm quark mass and the ratio m_c/m_s on these ensembles. The extrapolation to the chiral and continuum limits is performed using 5 lattice spacings ranging...
We show the heavy quark diffusion coefficient calculated on the lattice. The coefficient is obtained from the color-electric correlators via Kubo formula. The correlators are measured at 1.5$T_c$ on different large isotropic lattices in the quenched approximation under gradient flow. After continuum extrapolation we also extrapolate the continuum correlators back to zero flow time. The...
We present numerical results for 3d $\phi^4$ field theory on the $R\times S^2$ manifold in radial quantization using the quantum extension of the finite element method (QFE). The Monte Carlo study supports the QFE ansatz that once counterterms cancel effects from geometric defects in the UV, one reaches the nonperturbative conformal fixed point of the 3d Ising CFT. We demonstrate that...
When the realizations of QFT on quantum computer are discussed, the Kogut-Susskind formulation of lattice Hamiltonian is a popular option. We provide alternative formulations and discuss the pros and cons.
In this talk, we present a lattice determination of the coupling constant $\alpha_s$ in $N_f=3$ QCD for renormalization scales $\mu\in(1,2)$ GeV.
The computation has been performed on ensembles generated by the Coordinated Lattice Simulations (CLS) consortium, with tree-level Symanzik-improved gauge action and Wilson O(a)-improved fermions. Our approach is based on the study of...
We present results of chiral condensates, masses and decay constants of neutral pseudo scalar mesons in (2+1)-flavor QCD in the presence of external magnetic fields at zero temperature. We discuss the validity of Gell-Mann-Oakes-Renner relation in a wide region of magnetic field strength $eB$ up to around 3.5 GeV$^2$. The simulations were performed on $32^3\times96$ lattices using the Highly...
We perform a digital quantum simulation of the Schwinger model with the theta term, which is practically inaccessible by standard lattice Monte Carlo simulations. We construct the true vacuum state of a lattice Schwinger model using adiabatic state preparation which, in turn, allows us to compute an expectation value of the fermion mass operator with respect to the vacuum. Upon taking a...
The decomposition of energy and momentum in the hadron in terms of quark and gluon constituents is of fundamental importance to hadron structure, and with the ongoing development of the future Electron-Ion Collider, there is tremendous interest in imaging the transverse distributions of these constituents. This program will be strengthened by complimentary studies in Lattice QCD, where a...
We report on our recent results of the shear viscosity $\eta$ of the classical Yang-Mills (CYM) field on a lattice by using the Green-Kubo formula, where the shear viscosity is calculated from the time-correlation function of the energy-momentum tensor in equilibrium. The point of our investigation consists in utilization of the inherent scale invariance of CYM, and thereby the possible...
The efficient digitization required for the quantum simulations of QCD can be obtained by approximating continuous SU(3) gluon fields by discrete subgroups. In this talk, we discuss on-going efforts to develop this program of digitization: deriving improved discrete group lattice actions, classical simulations for quantifying systematic errors, and implementable circuits for digital quantum computers.
We propose a method to compute a spectral sum appearing in the QCD sum rule from lattice correlators.
This spectral sum corresponds to the Borel transform of the vacuum polarization, which widely appears in the phenomenological study.
We discuss how to compute it from two-point correlation functions on the lattice.
We measure it for three lattice spacing and confirm that the method gives...
We propose the sparse modeling method to estimate the spectral function from the smeared correlation functions. We give a description of how to obtain the shear viscosity from the correlation function of the renormalized energy-momentum tensor (EMT) measured by the gradient flow method (C(t,τ)) for the quenched QCD at finite temperature. The measurement of the renormalized EMT in the gradient...
The range of energy scales normally accessible by large-volume lattice computations is typically fairly limited
($1/a simeq 1-4$ GeV) and potentially insufficient to reproduce high-energy perturbative results.
In order to match lattice results with more phenomenologically amenable schemes, such as the $\bar{MS}$ scheme, we must evolve the non-perturbative results to higher energies where...
In this report we present the results of lattice study of how rotation influences confinement/deconfinement transition in SU(3) gluodynamics. To conduct this study we pass to the reference frame which rotates with the system under consideration. In this reference frame rotation is accounted for by the external gravitational field. We calculate the Polyakov loop, its susceptibility
and...
We discuss continuous symmetries identities using the tensor formulation of lattice spin and gauge models. We show that the symmetries are encoded in the selection rules of the tensor. This allows truncations that preserve the symmetries exactly. We present the tensorial expression of the transfer matrix for Abelian gauge theories and explain how gauge fixing and Gauss's law relate.
We...
On a lattice with 2+1-flavor dynamical domain-wall fermions at the physical pion mass, we calculate the decay constants of the charmed and light vector mesons including D/D, Ds/Ds, phi and K. The lattice size is 48^396, which corresponds to a spatial extension of ~5.5 fm with the lattice spacing a~0.114 fm. For the valence quarks we use overlap fermions at several mass points close to...
The magnetic polarisability is a fundamental property of hadrons, which provides insight into their structure in the low-energy regime. The pion magnetic polarisability is calculated using lattice QCD in the presence of background magnetic fields. The results presented are facilitated by the introduction of a new magnetic-field dependent quark-propagator eigenmode projector and the use of the...
Quantum computing may offer the opportunity to simulate strongly-interacting field theories, such as quantum chromodynamics, with physical time evolution. This would give access to Minkowski signature correlators, in contrast to the Euclidean calculations routinely performed at present. However, as with present-day calculations, quantum computation strategies still require the restriction to a...
Signal-to-noise problem and excited states contamination, inter alia, make studies of the QCD string breaking phenomenon a challenging task in lattice QCD. The static quark potentials produced for these studies can be combined with the Born Oppenheimer approximation to give an important insight into I=0 quarkonium resonances. Precise determination of various lattice potentials are also needed...
In their seminal publication of 1990, Maiani and Testa showed that Euclidean correlators are contaminated by off-shell contributions, limiting a direct extraction of amplitudes away from threshold. In this presentation, we revisit and extend this work, and explore the connection with recent developments on the inverse problem in Lattice QCD.
The rare decay J/ψ→3γ, analog to Ortho-positronium decaying to 3γ in quantum electrodynamics, can provide a high precision test for the non-perturbative quantum chromodynamics. Such a decay process was first observed by CLEO collaboration in 2008 and then by BESIII in 2013. However, the relevant theoretical researches are very limited due to the dominant non-perturbative effects. We propose to...
The low-lying spectrum of charmed baryons is calculated in lattice QCD on the $32^3 \times 64$, $N_f = 2 + 1$ PACS-CS gauge configurations at the almost physical pion mass of 156 $MeV/c^2$. By employing a set of interpolating operators with different Dirac structures and quark-field smearings for the variational analysis, we extract the ground and first few excited states of the spin-1/2 and...
We review developments in calculating multi-hadron form-factors and transition processes via lattice QCD. Our primary tools are finite-volume scaling relations, which non-perturbatively map spectra and matrix elements to their corresponding infinite-volume amplitudes. We focus on two hadron processes probed by an external current, and provide various checks on the finite-volume formalism in...
A new scheme for color confinement in QCD due to violation of non-Abelian Bianchi identity (VNABI) is proposed and numerical results in pure SU2 and SU3 QCD supporting the scheme are shown.
Understanding the color confinement mechanism is not yet solved in QCD. The dual Meissner effect is one of the most promising pictures as the color confinement mechanism. Recently the dual Meissner picture due to violation of the non-Abelian Bianchi identities was proposed. In this talk, we show numerical results based on that picture in pure SU(3) gauge theory, especially almost perfect...
The properties of low-lying charmonium mesons offer points of high precision comparison between lattice QCD and experiment, if discretisation effects set by the charm quark mass can be controlled. Using $n_f=2+1+1$ configurations with the HISQ action, developed by the HPQCD collaboration to have very small discretisation errors, we achieve precision at or below the 1% level for a range of...
Using a non-relativistic EFT, we derive a general relativistic expression for the energy shift in finite volume. This includes the N-particle ground state, and the first two- and three-particle excited states. In addition, we probe the N particle energy shift formula in complex phi^4 theory. We investigate different fit models, that include relativistic effects, exponentially suppressed...
Mixing in the $\Sigma^0$--$\Lambda^0$ system is a direct consequence of broken isospin symmetry and is a measure of both isospin-symmetry breaking as well as general SU(3)-flavour symmetry breaking. In this talk we present a novel scheme for calculating the extent of the physical $\Sigma^0$--$\Lambda^0$ mixing using simulations in lattice QCD+QED and discuss some of its features and initial results.
Quark confinement is still an unsolved problem. The dual Meissner effect is one of the ideas of this mechanism. In this picture, it is considered that the color flux tube between quarks is caused by the condensation of monopole in the QCD vacuum. However, how to define monopole in QCD is a difficult problem. Recently, it was shown the violation of non-Abelian Bianchi identity is equal to...
Recently, many studies of quantum field theory with quantum computers have reported. Quantum calculation can only treat unitary evolution, so thermal physics is one of difficulty of it because one needs to produce mixed states within allowed operations. Towards resolving the problem, we attempt to investigate thermal physics with thermal pure quantum(TPQ) state formalism. TPQ state formalism...
An analysis of the lattice Landau gauge gluon and ghost propagators for pure Yang-Mills is performed using Padé approximants to compute their analytical structure. The gluon propagator is described by a pair of complex conjugate poles and a branch cut along the negative side of the Euclidean momenta. The ghost propagator revels a simple pole at zero momenta and the method identifies a branch...
Quantum polarization effects associated with the conformal anomaly in a static magnetic field background may generate a transverse electric current in the vacuum of massless particles (either bosons or fermions). The current may be produced either in an unbounded curved spacetime or in flat spacetime in a physically bounded system. In both cases, the magnitude of the electric current is...
We investigate the two-flavour Schwinger model in the canonical formulation with fixed fermion number.
We use Wilson fermions on the lattice and present a formalism which describes the Dirac operator with dimensionally reduced canonical operators.
These reduced operators allow the direct examination of different meson sectors and the determination of the energy spectrum in
each of the...
The Heavy quark Operator Product Expansion (HOPE) method allows one to extract information about light-cone matrix elements via local, instant form matrix elements. When applied to the calculation of the pion's light cone distribution amplitude, it allows (in principle) the full x dependence of the distribution amplitude to be determined. In practice, finite statistics and finite momenta mean...
We investigate Casimir energy for free fermions on the lattice.
The Casimir energy of fermion fields can be defined with the lattice regularization.
The continuum extrapolation of our results reproduces the Casimir energy known in continuum theory.
We also show the lattice effect for the Casimir energy.
The lattice effect is important as an artifact that should be well-understood in order...
We search for possibly existent bound states in the heavy-light tetraquark channels with quark content $ \bar{b}\bar{b}ud $, $ \bar{b}\bar{b}us $ and $ \bar{b}\bar{c}ud $ using lattice NRQCD for the heavy quarks. We use different gauge link ensembles with $ N_f=2+1 $ flavours of domain-wall fermions and consider a basis of local and non-local interpolators. Besides extracting the energy...
The moments of the pion light-cone distribution amplitude (LCDA) can be extracted by comparison with the operator product expansion of the pion hadronic tensor with an artificially heavy intermediate quark. We perform a preliminary lattice calculation of this hadronic tensor in the quenched approximation at multiple lattice spacings and use it to extract the continuum limit of the second...
We compute hybrid static potentials in SU(2) lattice gauge theory using a multilevel algorithm and three different small lattice spacings. The resulting static potentials, which are valid for quark-antiquark separations as small as 0.05 fm, are important e.g. when computing masses of heavy hybrid mesons in the Born-Oppenheimer approximation. We also discuss and exclude possible systematic...
We present a detailed study of the nucleon unpolarized parton distribution function (PDF) using the approach of parton pseudo-distribution functions. We use this method to extract PDFs from the lattice results obtained using simulations with the
light quark mass fixed to its physical value. Then, the physical Ioffe time distributions are obtained from the nucleon matrix elements extracted...
We study the defects that can be defined within the framework of lattice gauge theories, in the presence of anisotropic couplings and try to identify their target space avatars. These are relevant for describing topological insulators.
Recent studies by HAL QCD collaboration have been successful in calculating hadron interactions from the first principles of QCD. In this talk, we apply the Laplacian Heaviside (LapH) smearing for the two nucleon source operator to enhance overlap with the low-energy elastic states and calculate the s-wave nuclear force. Our potential with the LapH smeared source has similar structure and...
We suggest that in Yang-Mills theories the ratio R of the mass of the tensor glueball over the mass of the scalar glueball is a universal quantity that depends only on the dimensionality of the space. To support this conjecture, we compute numerically R for Sp(2N) gauge theories for N = 1, 2, 3, 4 in d=4 Euclidean dimensions on a lattice and we analyse our results together with previous...
We present a high-statistics lattice QCD determination of the valence parton distribution function (PDF) of pion, with a mass of 300 MeV, using two very fine lattice spacings of a = 0.06 fm and 0.04 fm. Our analysis use both RI-MOM and ratio-based schemes to renormalize the equal-time bi-local quark-bilinear matrix elements of pions boosted up to 2.4 GeV momenta. We reconstruct the x-dependent...
The glueballs in the SU(N) Yang-Mills theory are theoretically the most natural among composite dark matter scenarios.
In this work, we evaluate the interglueball potential in SU(N) lattice gauge theories using the HALQCD method and derive the glueball dark matter scattering cross section, and then constrain the scale parameter of the gauge theory from the observational data.
Tensor network is an attractive approach to field theory with
negative sign problem. The complex \phi^4 theory at finite density is a test bed for numerical algorithms to verify their effectiveness.
The model shows a characteristic feature called the Silver Blaze phenomenon associated with the sign problem in the large volume limit at low temperature. We analyze the four-dimensional model ...
We present a Lattice QCD investigation of the pion electromagnetic form factor based on gauge configurations generated by Extended Twisted Mass Collaboration with N_f = 2+1+1 dynamical quark flavors. The calculation is carried out at two different lattice spacing values directly at the physical point. Employing Wilson clover twisted mass fermions at maximal twist guarantees O(a) improved...
The need to reach high hadron momentum is key to calculations of Parton Distribution Functions and other measures of hadron structure within lattice QCD. Meanwhile, the distillation framework provides a valuable means both of more fully sampling the lattice, and of controlling the contribution of excited states. In this talk, we extend the distillation framework through the implementation of...
The generalization of Lattice Field Theory targeting in curved Riemann manifolds referred to as Quantum Finite Elements (QFE) requires geometrical tools.
A brief outline for the construction of a Simplicial Complex and
its Delaunay dual, the construction Finite Element of lattice action based on
the elegant Discrete Exterior Calculus (DEC) is given. The focus in on spheres and hyperbolic...
Despite the success of quantum chromodynamics (QCD) in describing the strong nuclear force, a clear picture of how this theory gives rise to the distinctive properties of confinement and dynamical chiral symmetry breaking at low energy is yet to be found. One of the more promising models used to explain these phenomena in recent times is known as the centre vortex model. In this work we...
Gauge anomaly in 4-dimensions can be viewed as a current inflow into an extra-dimension, where the total phase of the fermion partition function is given in a gauge invariant way by the Atiyah-Patodi-Singer(APS) eta-invariant of a 5-dimensional Dirac operator. However, this formalism requires a non-local boundary condition, which makes the physical roles of edge/bulk modes unclear and the...
In this talk, we highlight our group's recent developments on computing the Compton amplitude in a lattice approach. We briefly discuss how to access the Compton amplitude directly via the second-order Feynman-Hellmann theorem. As an application, we compute the nucleon Compton tensor across a range of photon momenta at an unphysical quark mass. This enables us to study the $Q^2$ dependence of...
We study ""shifted"" double-winding Wilson loop average in SU(N) lattice Yang-Mills theory by using both strong coupling expansions and numerical simulations.
We evaluate its average by changing the distance of a transverse direction.
From this result, we discuss how interactions between the two color flux tubes change, when the distance $R$ is varied.
Recently, in the context of the resurgence program, it was conjectured that the perturbative ambiguity caused by the IR renormalon is canceled against the semi-classical object called bion. This conjecture requires the circle compactification with the $Z_N$ twisted boundary condition, in which the bion solution is found. Contrary to this conjecture, we find that there is no IR renormalon in...
At the last lattice conference, we have proposed to investigate the massive Yang-Mills model, namely, Yang-Mills theory with a gauge-invariant gluon mass term, in order to clarify the mechanism of quark confinement in the Yang-Mills theory with massgap. The gluon mass term simulates the dynamically generated mass to be extracted in the low-energy effective theory of the Yang-Mills theory and...
An understanding of the partonic structure of hadrons is an essential ingredient in making precise predictions and measurements of hadronic cross-sections and various Standard, and Beyond Standard, Model parameters. Several encouraging proposals have been developed in the past decade that relate lattice calculable quantities with PDFs via frameworks akin to QCD factorization. We report results...
Contrary to the common wisdom, local bosonizations of fermionic systems exist in higher dimensions. Interestingly, resulting bosonic variables must satisfy local constraints of a gauge type. They effectively replace long distance exchange interactions. In this work we study in detail the properties of such a system which was proposed a long time ago. In particular, dependence of the...
The light-cone definition of Parton Distribution Functions (PDFs) does not allow for a direct ab initio determination employing methods of Lattice QCD simulations that naturally take place in Euclidean spacetime. In this presentation we focus on pseudo-PDFs where the starting point is the equal time hadronic matrix element with the quark and anti-quark fields separated by a finite distance. We...
The phase structure of QCD at finite density is expected to be revealed by the complex Langevin method (CLM), which is a promising approach to overcome the sign problem. In particular, we discuss the possibility of investigating the color superconductivity (CSC) on the lattice by the CLM. Towards that end, we predict the parameter region in which CSC occurs in lattice perturbation theory based...
In a recent work we investigated the existence of inhomogeneous chiral phases (i.e., a phase where the chiral condensate has a spatial dependence) in the 1+1-dimensional Gross-Neveu model at finite number of fermion flavors. In the present work we continue this investigation by studying the formation of baryons, their spatial distribution and their relation to the inhomogeneous chiral condensate.
This talk is about a bosonization procedure based on Clifford algebra-valued degrees of freedom, valid for spaces of any dimension. Its interpretation in terms of lattice Z_2 gauge theory will be presented. Brief comparison with other bosonization proposals will be given.
We report on our computation of the pseudoscalar-photon transition form factors from twisted mass lattice QCD for three pseudoscalar states, i.e. the neutral pion and the eta and eta' mesons, to determine the corresponding light pseudoscalar pole contributions in the dispersive analysis of hadronic light by light scattering in the muon g-2.
The neutral pion transition form factor is computed...
We perform a first calculation for the unpolarized parton distribution function of the $\Delta^+$ baryon using lattice QCD simulations within the framework of Large Momentum Effective Theory. Two ensembles of $N_f=2+1+1$ twisted mass fermions are utilized with a pion mass of 270 MeV and 360 MeV, respectively. The baryon, which is treated as a stable single-particle state, is boosted with...
Replica evolution of classical field is proposed as an approximate simulator of real-time quantum field dynamics at finite temperatures. We consider $N$ classical field configurations $(\phi_{\tx},\pi_{\tx} (\tau=0,1,\cdots N-1)$, dubbed as replicas, which interact with each other via the $\tau$-derivative terms and evolve with the classical equation of motion. The $\tau$-derivative terms in...
We explore the existence of tetraquark resonances with lattice QCD potentials computed for a static b̄b̄ pair in the presence of two light quarks ud. We use the Born-Oppenheimer approximation and an extension of the emergent wave method, where effects of the heavy quark spins are included via the mass difference of the B and the B* meson. Focus is given on a resonance with isospin I = 0 and...
