Latest in hep-lat

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Gauged And Ungauged: A Nonperturbative TestFeb 08 2018We study the thermodynamics of the `ungauged' D0-brane matrix model by Monte Carlo simulation. Our results appear to be consistent with the conjecture by Maldacena and Milekhin.
Event-by-Event Efficiency Fluctuations and Efficiency Correction for Cumulants of Superposed Multiplicity Distributions in Relativistic Heavy-ion Collision ExperimentsFeb 08 2018We performed systematic studies for the effects of event-by-event efficiency fluctuations on efficiency correction for cumulant analysis in relativistic heavy-ion collision experiments. Experimentally, particle efficiencies of events measured with different ... More
Disordered fermions, extra dimensions and a solvable Yang-Mills theoryFeb 07 2018Generalizing disorder couplings of the SYK model by means of SU(N) matrices we formulate a lattice model of fermions in d+1 dimensions. Integration of fermions yields an effective theory of Yang-Mills fields in d dimensions, the latter approaching the ... More
Perturbative matching of continuum and lattice quasi-distributionsFeb 07 2018Matching of the quasi parton distribution functions between continuum and lattice is addressed using lattice perturbation theory specifically with Wilson-type fermions. The matching is done for nonlocal quark bilinear operators with a straight Wilson ... More
A structural test for the conformal invariance of the critical 3d Ising modelFeb 07 2018How can a renormalization group fixed point be scale invariant without being conformal? Polchinski (1988) showed that this may happen if the theory contains a virial current -- a non-conserved vector operator of dimension exactly $(d-1)$, whose divergence ... More
$C$-$P$-$T$ anomaly in bosonic systemsFeb 06 2018We consider the $O(3)$ nonlinear sigma model with the $\theta$-term and its linear counterpart in 1+1D. The model has discrete time-reflection and space-reflection symmetries at any $\theta$, and enjoys the periodicity in $\theta\rightarrow \theta+2\pi$. ... More
Lee-Yang zeros in lattice QCD at finite baryon density from canonical approachFeb 06 2018We report Lee-Yang zeros behavior at finite temperature and density using the canonical approach in lattice QCD. The quark number densities are calculated at the pure imaginary chemical potential in lattice QCD. Canonical partition functions Z_C(n,T,V) ... More
Testing the criterion for correct convergence in the complex Langevin methodFeb 06 2018Recently the complex Langevin method (CLM) has been attracting attention as a solution to the sign problem, which occurs in Monte Carlo calculations when the effective Boltzmann weight is not real positive. An undesirable feature of the method, however, ... More
Automated lattice data generationFeb 02 2018The process of generating ensembles of gauge configurations (and measuring various observables over them) can be tedious and error-prone when done "by hand". In practice, most of this procedure can be automated with the use of a workflow manager. We discuss ... More
On the zero-crossing of the three-gluon Green's function from lattice simulationsFeb 02 2018We report on some efforts recently made in order to gain a better understanding of some IR properties of the 3-point gluon Green's function by exploiting results from large-volume quenched lattice simulations. These lattice results have been obtained ... More
SO(3) "Nuclear Physics" with ultracold GasesJan 31 2018An ab initio calculation of nuclear physics from Quantum Chromodynamics (QCD), the fundamental SU(3) gauge theory of the strong interaction, remains an outstanding challenge. Here, we discuss the emergence of key elements of nuclear physics using an SO(3) ... More
Instanton liquid properties from lattice QCDJan 30 2018We examined the instanton contribution to the QCD configurations generated from lattice QCD for $N_F=0$, $N_F=2+1$ and $N_F=2+1+1$ dynamical quark flavors from two different and complementary approaches. First via the use of Gradient flow, we computed ... More
On the chiral extrapolation of charmed meson massesJan 30 2018We perform an analysis of QCD lattice data on charmed meson masses. The quark-mass dependence of the data set is used to gain information on the size of counter terms of the chiral Lagrangian formulated with open-charm states with J^P= 0^- and J^P =1^- ... More
Strange nucleon electromagnetic form factors from lattice QCDJan 29 2018We evaluate the strange nucleon electromagnetic form factors using an ensemble of gauge configurations generated with two degenerate maximally twisted mass clover-improved fermions with mass tuned to approximately reproduce the physical pion mass. In ... More
0+ and 1+ heavy-light exotic mesons at N2LO in the chiral limitJan 27 2018We use QCD spectral sum rules (QSSR) and the factorization properties of molecule and four-quark currents to estimate the masses and couplings of the 0+ and 1+ molecules and four-quark at N2LO of PT QCD. We include in the OPE the contributions of non-perturbative ... More
N* Structure and Strong QCDJan 25 2018In attempting to match QCD with Nature, it is necessary to confront the many complexities of strong, nonlinear dynamics in relativistic quantum field theory, e.g. the loss of particle number conservation, the frame and scale dependence of the explanations ... More
From Heavy-Ion Collisions to Compact Stars: Equation of State and Relevance of the System SizeJan 24 2018In this article, we start by presenting state-of-the-art methods allowing us to compute moments related to the globally conserved baryon number, by means of first principle resummed perturbative frameworks. We focus on such quantities for they convey ... More
Multigrid for Staggered Lattice FermionsJan 24 2018Critical slowing down in Krylov methods for the Dirac operator presents a major obstacle to further advances in lattice field theory as it approaches the continuum solution. Here we formulate a multi-grid algorithm for the Kogut-Susskind (or staggered) ... More
Calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic momentJan 22 2018We present a first-principles lattice QCD+QED calculation at physical pion mass of the leading-order hadronic vacuum polarization contribution to the muon anomalous magnetic moment. The total contribution of up, down, strange, and charm quarks including ... More
Valence-quark structure N* resonances from DSEsJan 22 2018We present a unified Quantum Chromodynamics (QCD)-based description of elastic and transition electromagnetic form factors involving the nucleon and its resonances. We compare predictions made using a framework built upon a Faddeev equation kernel and ... More
Hadron tomography and its application to gravitational radii of hadronsJan 19 2018Hadron tomography has been investigated by three-dimensional structure functions, such as generalized parton distributions (GPDs) and generalized distribution amplitudes (GDAs). The GDAs are $s$-$t$ crossed quantities of the GPDs, and both functions probe ... More
Renormalization scheme and gauge (in)dependence of the generalized Crewther relation: what are the real grounds of the $β$-factorization property?Jan 18 2018The scheme and gauge dependence of the factorization property of the RG $\beta$-function in the $SU(N_c)$ QCD generalized Crewther relation (GCR), which connects the non-singlet contributions to the Adler and Bjorken polarized sum rule functions, is investigated ... More
Baryon spectrum of SU(4) composite Higgs theory with two distinct fermion representationsJan 17 2018We use lattice simulations to compute the baryon spectrum of SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. This model is closely related to a composite ... More
Nucleon viewed as a Borromean Bound-StateJan 15 2018We explain how the emergent phenomenon of dynamical chiral symmetry breaking ensures that Poincar\'e covariant analyses of the three valence-quark scattering problem in continuum quantum field theory yield a picture of the nucleon as a Borromean bound-state, ... More
XYZ - SU3 Breakings from Laplace Sum Rule at Higher Orders: SummaryJan 09 2018This talk reviews and summarizes some of our results in [1] on XYZ- SU3 Breakings obtained from QCD Laplace Sum Rules (LSR) at next-to-next-leading order (N2LO) of perturbative (PT) theory and including next-to-leading order (NLO) SU3 breaking corrections ... More
The $\big\langle A^2 \big\rangle$ Asymmetry and Longitudinal Propagator in Lattice $SU(2)$ Gluodynamics at $T\simeq T_c$Jan 08 2018We study numerically the chromoelectric-chromomagnetic asymmetry of the dimension two gluon condensate as well as the longitudinal gluon propagator at $T\simeq T_c$ in the Landau-gauge $SU(2)$ lattice gauge theory. We show that substantial correlation ... More
A fresh look at the (non-)Abelian Landau-Khalatnikov-Fradkin transformationsJan 05 2018The Landau-Khalatnikov-Fradkin transformations (LKFTs) allow to interpolate $n$-point functions between different gauges. We first offer an alternative derivation of these LKFTs for the gauge and fermions field in the Abelian (QED) case when working in ... More
Nonperturbative study of dynamical SUSY breaking in $\mathcal{N} = (2, 2)$ Yang-MillsDec 29 2017We examine the possibility of dynamical supersymmetry breaking in two-dimensional $\mathcal{N} = (2, 2)$ supersymmetric Yang-Mills theory. The theory is discretized on a Euclidean spacetime lattice using a supersymmetric lattice action. We compute the ... More
$K \to π$ matrix elements of the chromomagnetic operator on the latticeDec 28 2017We present the results of the first lattice QCD calculation of the $K \to \pi$ matrix elements of the chromomagnetic operator $O_{CM} = g\, \bar s\, \sigma_{\mu\nu} G_{\mu\nu} d$, which appears in the effective Hamiltonian describing $\Delta S = 1$ transitions ... More
The ghost-gluon vertex in the presence of the Gribov horizonDec 27 2017We consider Yang-Mills theories quantized in the Landau gauge in the presence of the Gribov horizon via the refined Gribov Zwanziger (RGZ) framework. As the restriction of the gauge path integral to the Gribov region is taken into account, the resulting ... More
$B$- and $D$-meson leptonic decay constants from four-flavor lattice QCDDec 26 2017Dec 31 2017We calculate the leptonic decay constants of heavy-light pseudoscalar mesons with charm and bottom quarks in lattice quantum chromodynamics on four-flavor QCD gauge-field configurations with dynamical $u$, $d$, $s$, and $c$ quarks. We analyze over twenty ... More
User's guide to Monte Carlo methods for evaluating path integralsDec 22 2017We give an introduction to the calculation of path integrals on a lattice, with the quantum harmonic oscillator as an example. In addition to providing an explicit computational setup and corresponding pseudocode, we pay particular attention to the existence ... More
From the $SU(2)$ Quantum Link Model on the Honeycomb Lattice to the Quantum Dimer Model on the Kagomé Lattice: Phase Transition and Fractionalized Flux StringsDec 22 2017Jan 03 2018We consider the $(2+1)$-d $SU(2)$ quantum link model on the honeycomb lattice and show that it is equivalent to a quantum dimer model on the Kagom\'e lattice. The model has crystalline confined phases with spontaneously broken translation invariance associated ... More
Possible higher order phase transition in large-$N$ gauge theory at finite temperatureDec 21 2017We analyze the phase structure of $SU(\infty)$ gauge theory at finite temperature using matrix models. Our basic assumption is that the effective potential is dominated by double-trace terms for the Polyakov loops. As a function of the temperature, a ... More
Abelian and non-Abelian Berry curvatures in lattice QCDDec 06 2017We studied the Berry curvature of the massive Dirac fermion in 3+1 dimensions. For the non-interacting Dirac fermion, the Berry curvature is non-Abelian because of the degeneracy of positive and negative helicity modes. We calculated the non-Abelian Berry ... More
Baryonic and mesonic 3-point functions with open spin indicesNov 07 2017We have implemented a new way of computing three-point correlation functions. It is based on a factorization of the entire correlation function into two parts which are evaluated with open spin- (and to some extent flavor-) indices. This allows us to ... More
Local multiboson factorization of the quark determinantNov 05 2017We discuss the recently proposed multiboson domain-decomposed factorization of the gauge-field dependence of the fermion determinant in lattice QCD. In particular, we focus on the case of a lattice divided in an arbitrary number of thick time slices. ... More
Topological charge and cooling scales in pure SU(2) lattice gauge theoryOct 25 2017Using Monte Carlo simulations with overrelaxation, we have equilibrated lattices up to $\beta=2.928$, size $60^4$ for pure SU(2) lattices gauge theory with the Wilson action. We calculate topological charges with the cooling method and find that they ... More
QCD in a moving frame: an exploratory studyOct 25 2017The framework of shifted boundary conditions has proven to be a very powerful tool for the non-perturbative investigation of thermal quantum field theories. For instance, it has been successfully considered for the determination of the equation of state ... More
Multi-boson block factorization of fermionsOct 25 2017Dec 20 2017The numerical computations of many quantities of theoretical and phenomenological interest are plagued by statistical errors which increase exponentially with the distance of the sources in the relevant correlators. Notable examples are baryon masses ... More
Investigating BSM Models with Large Scale SeparationOct 24 2017Mass-split systems based on a conformal infrared fixed point provide a low-energy effective description of beyond the standard model systems with large scale separation. We report results of exploratory investigations with four light and eight heavy flavors ... More
Medium effects and parity doubling of hyperons across the deconfinement phase transitionOct 23 2017We analyse the behaviour of hyperons with strangeness $S=-1$,$-2$,$-3$ in the hadronic and quark gluon plasma phases, with particular interest in parity doubling and its emergence as the temperature grows. This study uses our FASTSUM anisotropic $N_f\!\!=$~2+1 ... More
Phases of a strongly coupled four-fermion theoryOct 23 2017We present ongoing investigations of a four-dimensional lattice field theory with four massless reduced staggered fermions coupled through an SU(4)-invariant four-fermion interaction. As in previous studies of four-fermion and Higgs--Yukawa models with ... More
Supermultiplets in N=1 SUSY SU(2) Yang-Mills TheoryOct 20 2017We study $\mathcal{N}=1$ supersymmetric Yang-Mills theory (SYM) on the lattice. The non-perturbative nature of supersymmetric field theories is still largely unknown. Similarly to QCD, SYM is confining and contains strongly bound states. Applying the ... More
Improved results for the mass spectrum of N=1 supersymmetric SU(3) Yang-Mills theoryOct 19 2017This talk summarizes the results of the DESY-M\"unster collaboration for $\mathcal{N}=1$ supersymmetric Yang-Mills theory with the gauge group SU(3). It is an updated status report with respect to our preliminary data presented at the last conference. ... More
Testing the holographic principle using lattice simulationsOct 17 2017The lattice studies of maximally supersymmetric Yang-Mills (MSYM) theory at strong coupling and large N is important for verifying gauge/gravity duality. Due to the progress made in the last decade, based on ideas from topological twisting and orbifolding, ... More
Getting even with CLEOct 16 2017In the landscape of approaches toward the simulation of Lattice Models with complex action the Complex Langevin (CL) appears as a straightforward method with a simple, well defined setup. Its applicability, however, is controlled by certain specific conditions ... More
Large scale separation and hadronic resonances from a new strongly interacting sectorOct 05 2017A large separation of scales is frequently required by theories describing physics beyond the Standard Model. In mass-split models with some massless (light) and some heavy flavors, large scale separation arises by construction if the system is conformal ... More
Two dimensional super QCD on a latticeOct 04 2017We construct a lattice theory with one exact supersymmetry which consists of fields transforming in both the adjoint and fundamental representations of a U(Nc) gauge group. In addition to gluons and gluinos, the theory contains Nf flavors of fermion in ... More
Baryons in the plasma: in-medium effects and parity doublingOct 02 2017We investigate the fate of baryons made out of u, d and s quarks in the hadronic gas and the quark-gluon plasma, using nonperturbative lattice simulations, employing the FASTSUM anisotropic Nf=2+1 ensembles. In the confined phase a strong temperature ... More
Testing holography using lattice super-Yang--Mills on a 2-torusSep 20 2017We consider maximally supersymmetric SU(N) Yang--Mills theory in Euclidean signature compactified on a flat two-dimensional torus with anti-periodic (`thermal') fermion boundary conditions imposed on one cycle. At large N, holography predicts that this ... More
One-dimensional anyons in relativistic field theorySep 19 2017We study relativistic anyon field theory in 1+1 dimensions. While (2+1)-dimensional anyon fields are equivalent to boson or fermion fields coupled with the Chern-Simons gauge fields, (1+1)-dimensional anyon fields are equivalent to boson or fermion fields ... More
Extraction of nucleon axial charge and radius from lattice QCD results using baryon chiral perturbation theoryAug 29 2017Feb 07 2018We calculate the nucleon axial form factor up to the leading one-loop order in a covariant chiral effective field theory with the $\Delta(1232)$ resonance as an explicit degree of freedom. We fit the axial form factor to the latest lattice QCD data and ... More
Estimates of Scaling Violations for Pure SU(2) LGTAug 28 2017We investigate the approach of pure SU(2) lattice gauge theory with the Wilson action to its continuum limit using the deconfining transition, Luescher's gradient flow, and the cooling flow to set the scale. Of those, the cooling flow turns out to be ... More
Freezeout systematics due to the hadron spectrumAug 27 2017Nov 08 2017We investigate systematics of the freezeout surface in heavy ion collisions due to the hadron spectrum. The role of suspected resonance states that are yet to be confirmed experimentally in identifying the freezeout surface has been investigated. We have ... More
Numerical study of the $2+1d$ Thirring model with U($2N$)-invariant fermionsAug 25 2017In 2+1 dimensions the global U($2N$) symmetry associated with massless Dirac fermions is broken to U($N)\otimes$U($N$) by a parity-invariant mass. I will show how to adapt the domain wall formulation to recover the U($2N$)-invariant limit in interacting ... More
Topology and strong four fermion interactions in four dimensionsAug 22 2017Dec 31 2017We study massless fermions interacting through a particular four fermion term in four dimensions. Exact symmetries prevent the generation of bilinear fermion mass terms. We determine the structure of the low energy effective action for the auxiliary field ... More
Isoscalar $ππ, K\overline{K}, ηη$ scattering and the $σ, f_0, f_2$ mesons from QCDAug 20 2017We present the first lattice QCD study of coupled isoscalar $\pi\pi,K\overline{K},\eta\eta$ $S$- and $D$-wave scattering extracted from discrete finite-volume spectra computed on lattices which have a value of the quark mass corresponding to $m_\pi\sim391$ ... More
Revisiting the Hybrid Quantum Monte Carlo Method for Hubbard and Electron-Phonon ModelsAug 11 2017A unique feature of the Hybrid Quantum Monte Carlo (HQMC) method is the potential to simulate negative sign free lattice fermion models with sub-cubic scaling in system size. Here we will revisit the algorithm for various models. We will show that for ... More
Testing Fermion Universality at a Conformal Fixed PointAug 10 2017Universality of various fermion formulations is well established in QCD-like theories defined around the perturbative $g^2=0$ fixed point. These arguments do not apply for conformal systems that exhibit an infrared fixed point at non-vanishing $g^2$ coupling. ... More
Repulsive baryonic interactions and lattice QCD observables at imaginary chemical potentialAug 09 2017Oct 19 2017The first principle lattice QCD methods allow to calculate the thermodynamic observables at finite temperature and imaginary chemical potential. These can be compared to the predictions of various phenomenological models. We argue that Fourier coefficients ... More
Lattice simulation with the Majorana positivityJul 18 2017While the sign problem of the Dirac fermion is conditioned by the semi-positivity of a determinant, that of the Majorana fermion is conditioned by the semi-positivity of a Pfaffian. We introduce one sufficient condition for the semi-positivity of a Pfaffian. ... More
Exotic Doubly Charmed Ds0*(2317)D and Ds1*(2460)D* MoleculesJul 12 2017The $D_{s0}^*(2317) D$ and $D_{s1}^*(2460) D^*$ heavy meson systems can exchange a kaon that is emitted in S-wave owing to the opposite intrinsic parity of the $D_{s0}^*$($D_{s1}^*$) and $D$($D^*$) mesons. As a consequence of the mass difference of the ... More
Scattering processes and resonances from lattice QCDJun 20 2017The vast majority of hadrons observed in nature are not stable under the strong interaction, rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers ... More
Heavy Baryon Molecules in Effective Field TheoryJun 08 2017We discuss the effective field theory description of bound states composed of a heavy baryon and antibaryon. This framework is a variation of the ones already developed for heavy meson-antimeson states to describe the $X(3872)$ or the $Z_c$ and $Z_b$ ... More
QCDVis: a tool for the visualisation of Quantum Chromodynamics (QCD) DataJun 04 2017Quantum chromodynamics, most commonly referred to as QCD, is a relativistic quantum field theory for the strong interaction between subatomic particles called quarks and gluons. The most systematic way of calculating the strong interactions of QCD is ... More
Machine Learning of Explicit Order Parameters: From the Ising Model to SU(2) Lattice Gauge TheoryMay 16 2017We present a procedure for reconstructing the decision function of an artificial neural network as a simple function of the input, provided the decision function is sufficiently symmetric. In this case one can easily deduce the quantity by which the neural ... More
Topology (and axion's properties) from lattice QCD with a dynamical charmMay 04 2017We present results on QCD with four dynamical flavors in the temperature range $0.9 \lesssim T/T_c \lesssim 2$. We have performed lattice simulations with Wilson fermions at maximal twist and measured the topological charge with gluonic and fermionic ... More
Quantum Monte Carlo simulation of a two-dimensional Majorana lattice modelApr 29 2017Jul 18 2017We study interacting Majorana fermions in two dimensions as a low-energy effective model of a vortex lattice in two-dimensional time-reversal-invariant topological superconductors. For that purpose, we implement ab-initio quantum Monte Carlo simulation ... More
The ALF (Algorithms for Lattice Fermions) project release 1.0. Documentation for the auxiliary field quantum Monte Carlo codeApr 01 2017Jun 23 2017The Algorithms for Lattice Fermions package provides a general code for the finite temperature auxiliary field quantum Monte Carlo algorithm. The code is engineered to be able to simulate any model that can be written in terms of sums of single-body operators, ... More
Light baryons below and above the deconfinement transition: medium effects and parity doublingMar 27 2017Jun 01 2017We study what happens to the Nucleon, Delta and Omega baryons in the hadronic gas and the quark-gluon plasma, with particular interest in parity doubling and its emergence as the plasma is heated. This is done using simulations of lattice QCD, employing ... More
The role of the Euclidean signature in lattice calculations of quasi-distributions and other non-local matrix elementsMar 17 2017Jul 17 2017Lattice quantum chromodynamics (QCD) provides the only known systematic, nonperturbative method for first-principles calculations of nucleon structure. However, for quantities such as lightfront parton distribution functions (PDFs) and generalized parton ... More
Joint Contour Net analysis of lattice QCD dataMar 07 2017Jun 04 2017Lattice Quantum Chromodynamics (QCD) is an approach used by theoretical physicists to model the strong nuclear force. This works at the sub-nuclear scale to bind quarks together into hadrons including the proton and neutron. One of the long term goals ... More
Neutron-proton scattering at next-to-next-to-leading order in Nuclear Lattice Effective Field TheoryFeb 17 2017We present a systematic study of neutron-proton scattering in Nuclear Lattice Effective Field Theory (NLEFT), in terms of the computationally efficient radial Hamiltonian method. Our leading-order (LO) interaction consists of smeared, local contact terms ... More
Constraining the hadronic spectrum through QCD thermodynamics on the latticeFeb 03 2017Fluctuations of conserved charges allow to study the chemical composition of hadronic matter. A comparison between lattice simulations and the Hadron Resonance Gas (HRG) model suggested the existence of missing strange resonances. To clarify this issue ... More
Relating the finite-volume spectrum and the two-and-three-particle $S$ matrix for relativistic systems of identical scalar particlesJan 25 2017Apr 30 2017Working in relativistic quantum field theory, we derive the quantization condition satisfied by coupled two- and three-particle systems of identical scalar particles confined to a cubic spatial volume with periodicity $L$. This gives the relation between ... More
Classification of sign-problem-free relativistic fermions on the basis of the Majorana positivityJan 25 2017Apr 24 2017We classify the sign-problem-free relativistic fermion actions on the basis of the Majorana representation. In the Majorana representation, the sign-problem-free condition is given by the semi-positivity of a Pfaffian. We show that the known sign-problem-free ... More
Renormalisation of the scalar energy-momentum tensor with the Wilson flowDec 22 2016The non-perturbative computation of the energy-momentum tensor can be used to study the scaling behaviour of strongly coupled quantum field theories. The Wilson flow is an essential tool to find a meaningful formulation of the energy-momentum tensor on ... More
Deconfinement, gradient and cooling scales for pure SU(2) lattice gauge theoryDec 21 2016We investigate the approach of pure SU(2) lattice gauge theory with the Wilson action to its continuum limit using the deconfining phase transition, the gradient flow and the cooling flow to set the scale. For the gradient and cooling scales we explore ... More
Domain decomposition and multilevel integration for fermionsDec 19 2016Mar 07 2017The numerical computation of many hadronic correlation functions is exceedingly difficult due to the exponentially decreasing signal-to-noise ratio with the distance between source and sink. Multilevel integration methods, using independent updates of ... More
Progress in three-particle scattering from LQCDDec 18 2016We present the status of our formalism for extracting three-particle scattering observables from lattice QCD (LQCD). The method relies on relating the discrete finite-volume spectrum of a quantum field theory with its scattering amplitudes. As the finite-volume ... More
A brief history of the introduction of generalized ensembles to Markov chain Monte Carlo simulationsDec 13 2016The most efficient weights for Markov chain Monte Carlo calculations of physical observables are not necessarily those of the canonical ensemble. Generalized ensembles, which do not exist in nature but can be simulated on computers, lead often to a much ... More
Including heavy spin effects in the prediction of a $\bar{b} \bar{b} u d$ tetraquark with lattice QCD potentialsDec 08 2016We investigate spin effects in four-quark systems consisting of two heavy anti-bottom quarks and two light up/down quarks. To this end we use the Born-Oppenheimer approximation. We utilize potentials of two static antiquarks in the presence of two quarks ... More
QEX: a framework for lattice field theoriesDec 08 2016We present a new software framework for simulating lattice field theories. It features an intuitive programming interface, while simultaneously achieving high performance supercomputing, all in one programming language, Nim. With a macro system based ... More
Non-equilibrium study of the Chiral Magnetic Effect from real-time simulations with dynamical fermionsDec 07 2016We present a real-time lattice approach to study the non-equilibrium dynamics of vector and axial charges in $SU(N) \times U(1)$ gauge theories. Based on a classical description of the non-Abelian and Abelian gauge fields, we include dynamical fermions ... More
Slope and curvature of the hadron vacuum polarization at vanishing virtuality from lattice QCDDec 07 2016We compute the slope and curvature, at vanishing four-momentum transfer squared, of the leading order hadron vacuum polarization function, using lattice QCD. Calculations are performed with 2+1+1 flavors of staggered fermions directly at the physical ... More
Thermodynamics of strongly interacting plasma with high accuracyDec 07 2016The equation of state of $SU(3)$ Yang-Mills theory is investigated in the framework of a moving reference frame. Results for the entropy density, the pressure, the energy density, and the trace anomaly are presented for temperatures ranging from 0 to ... More
Sea quark QED effects and twisted mass fermionsDec 07 2016We show that maximally twisted mass fermions can be employed to regularize on the lattice the fully unquenched QCD+QED theory with vanishing $\theta$-term. We discuss how the critical mass of the up and down quarks can be conveniently determined beyond ... More
Isospin-0 $ππ$ s-wave scattering length from twisted mass lattice QCDDec 06 2016We present results for the isospin-0 $\pi\pi$ s-wave scattering length calculated with Osterwalder-Seiler valence quarks on Wilson twisted mass gauge configurations. We use three $N_f = 2$ ensembles with unitary pion mass at its physical value, at 240MeV ... More
Numerical Analysis of Discretized ${\cal N}=(2,2)$ SYM on PolyhedraDec 06 2016We perform a numerical simulation of the two-dimensional ${\cal N}=(2,2)$ supersymmetric Yang-Mills (SYM) theory on the discretized curved space. The $U(1)_{A}$ anomaly of the continuum theory is maintained also in the discretized theory as an unbalance ... More
Evidence of effective axial U(1) symmetry restoration at high temperature QCDDec 06 2016We study the axial U(1) symmetry at finite temperature in two-flavor lattice QCD. Employing the Mobius domain-wall fermions, we generate gauge configurations slightly above the critical temperature Tc with different lattice sizes L = 2-4 fm. Our action ... More
$α_s$ in 2016 from the (revised) ALEPH data for $τ$ decayDec 06 2016We summarize a comparison of the two strategies which are currently available in the literature for determining the value of $\alpha_s(m_\tau)$. We will refer to these as the truncated Operator Product Expansion model and the Duality Violation model. ... More
Numerical determination of the $Λ$-parameter in SU(3) gauge theory from the twisted gradient flow couplingDec 06 2016We estimate the $\Lambda$-parameter in the $\overline{\mathrm{MS}}$ scheme for the SU(3) pure gauge theory with the twisted gradient flow method non-perturbatively. We obtain $\Lambda_{\overline{\mathrm{MS}}}/\sqrt{\sigma}=0.527(13)(10)$ and $r_{0}\Lambda_{\overline{\mathrm{MS}}}=0.605(15)(5)$ ... More
Abelian spatial string tension in finite temperature SU(2) gauge theoryDec 06 2016We investigate Abelian and monopole contributions to spatial string tension in the deconfined phase of finite temperature SU(2) gauge theory without imposing any gauge fixing conditions. Lattice calculations of non-Abelian and Abelian spatial string tensions ... More
New simulation strategies for lattice gauge theoryDec 06 2016Despite the numerous successful applications of lattice QCD in nuclear and particle theory, fundamental algorithmic challenges remain. Among those, relevant for numerical studies of QCD on a space-time torus, is topological freezing--a form of critical ... More
Quasi parton distributions and the gradient flowDec 05 2016We propose a new approach to determining quasi parton distribution functions (PDFs) from lattice quantum chromodynamics. By incorporating the gradient flow, this method guarantees that the lattice quasi PDFs are finite in the continuum limit and evades ... More
Lattice QCD spectroscopy for hadronic CP violationDec 05 2016The interpretation of nuclear electric dipole moment (EDM) experiments is clouded by large theoretical uncertainties associated with nonperturbative matrix elements. In various beyond-the-Standard Model scenarios nuclear and diamagnetic atomic EDMs are ... More
Pion structure from twisted mass lattice QCD down to the physical pion massDec 05 2016We present an investigation of pion structure based on ETMC $N_f=2$ and $N_f=2+1+1$ twisted mass configurations at maximal twist. We compute the first moment of the quark momentum fraction of the pion, $\langle x \rangle$ and the electromagnetic form ... More
Twisted mass Dirac spectrumDec 05 2016The microscopic spectral density for lattice QCD with $N_f = 2+1+1$ twisted mass fermions is computed numerically and compared to analytical predictions of Wilson $\chi$-PT at a fixed index. In this way, we obtain results for the chiral condensate and ... More
Twisted mass Dirac spectrumDec 05 2016Dec 08 2016The microscopic spectral density for lattice QCD with $N_f = 2+1+1$ twisted mass fermions is computed numerically and compared to analytical predictions of Wilson $\chi$-PT at a fixed index. In this way, we obtain results for the chiral condensate and ... More