Tue·Dec 7, 2021Tuesday·December 7, 2021

1. 01*

   Prediction and compression of lattice QCD data using machine learning algorithms on quantum annealer

   Boram Yoon🇺🇸 · Chia Cheng Chang🇯🇵 · Garrett T. Kenyon🇺🇸 · Nga T.T. Nguyen🇺🇸 · Ermal Rrapaj🇺🇸

   We present regression and compression algorithms for lattice QCD data utilizing the efficient binary optimization ability of quantum annealers. In the regression algorithm, we encode the correlation between the input and output variables into a sparse coding machine learning algorithm. The trained correlation pattern is used to predict lattice QCD observables of unseen lattice configurations from other observables measured on the lattice. In the compression algorithm, we define a mapping from lattice QCD data of floating-point numbers to the binary coefficients that closely reconstruct the input data from a set of basis vectors. Since the reconstruction is not exact, the mapping defines a lossy compression, but, a reasonably small number of binary coefficients are able to reconstruct the input vector of lattice QCD data with the reconstruction error much smaller than the statistical fluctuation. In both applications, we use D-Wave quantum annealers to solve the NP-hard binary optimization problems of the machine learning algorithms.

   hep-latcs.LGquant-phPoS(2021)·2 citations
2. 02*

   Abelian monopoles of the Dirac type and color confinement in QCD

   Tsuneo Suzuki🇯🇵 · Atsuki Hiraguchi🇹🇼 · Katsuya Ishiguro🇯🇵

   We present results of $SU(3)$ Monte-Carlo studies of a new color confinement scheme due to Abelian-like monopoles of the Dirac type without any gauge-fixing. We get (1) perfect Abelian dominance with respect to the static potentials on $12^4\sim 16^4$ lattice at $\beta =5.6-5.8$ using the multilevel method, (2) monopole as well as Abelian dominances with respect to the static potentials by evaluating Polyakov loop correlators on $24^3\times 4$ lattice at $\beta =5.6$. (3) Abelian dual Meissner effects are studied directly by measuring Abelian color fields and monopole currents around the static source. The vacuum in pure $SU(3)$ seems to be of the type 1 near the border between both types, although scaling is not studied yet.

   hep-lat0 citations
3. 03*

   New approach to lattice QCD at finite density: reweighting without an overlap problem

   Attila Pasztor🇭🇺 · Szabolcs Borsanyi🇩🇪 · Zoltan Fodor🇩🇪 · Kornel Kapas🇭🇺 · Sandor D. Katz🇭🇺 · Matteo Giordano🇭🇺 · Daniel Nogradi🇭🇺 · Chik Him Wong🇩🇪

   Approaches to finite baryon density lattice QCD usually suffer from uncontrolled systematic uncertainties in addition to the well-known sign problem. We test a method - sign reweighting - that works directly at finite chemical potential and is yet free from any such uncontrolled systematics: with this approach the only problem is the sign problem itself. In practice the approach involves the generation of configurations with the positive fermionic weights given by the absolute value of the real part of the quark determinant, and a reweighting by a sign. There are only two sectors, +1 and -1 and as long as the average $⟨\pm ⟩\ne 0$ (with respect to the positive weight) this discrete reweighting has no overlap problem - unlike reweighting from $\mu =0$ - and the results are reliable. We also present results based on this algorithm on the phase diagram of lattice QCD with two different actions: as a first test, we apply the method to calculate the position of the critical endpoint with unimproved staggered fermions at $N_{\tau }=4$; as a second application, we study the phase diagram with 2stout improved staggered fermions at $N_{\tau }=6$. This second one is already a reasonably fine lattice - relevant for phenomenology. We demonstrate that the method penetrates the region of the phase diagram where the Taylor and imaginary chemical potential methods lose predictive power.

   hep-lathep-phnucl-thPoS(2022)·4 citations
4. 04*

   Lattice QCD Determination of the Bjorken-$x$ Dependence of Parton Distribution Functions at Next-to-next-to-leading Order

   Xiang Gao🇨🇳 · Andrew D. Hanlon🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Philipp Scior🇺🇸 · Sergey Syritsyn🇺🇸 · Yong Zhao🇺🇸

   We report the first lattice QCD calculation of pion valence quark distribution with next-to-next-to-leading order perturbative matching correction, which is done using two fine lattices with spacings $a=0.04$ fm and $0.06$ fm and valence pion mass $m_{\pi }=300$ MeV, at boost momentum as large as $2.42$ GeV. As a crucial step to control the systematics, we renormalize the pion valence quasi distribution in the recently proposed hybrid scheme, which features a Wilson-line mass subtraction at large distances in coordinate space, and develop a procedure to match it to the $\overline{\mathrm{MS}}$ scheme. We demonstrate that the renormalization and the perturbative matching in Bjorken-$x$ space yield a reliable determination of the valence quark distribution for $0.03\lesssim x\lesssim 0.80$ with 5-20\% uncertainties.

   hep-lathep-exhep-phnucl-ex+1PRL(2022)·96 citations
5. 05*

   Inhomogeneous Phases in the Chiral Gross-Neveu Model on the Lattice

   Keita Horie🇯🇵 · Chiho Nonaka🇯🇵

   We discuss possible existence of inhomogeneous phase in low temperature and high density region in the 1+1 dimensional chiral Gross-Neveu ( $\chi$GN${}_2$ ) model on the lattice. First we investigate the phase structure of the $\chi$GN${}_2$ model at vanishing chemical potential, changing temperature. From behavior of ${\Delta }^2={\Sigma }^2+{\Pi }^2$ as a function of Monte Carlo time, a candidate of an order parameter for chiral symmetry in the $\chi$GN${}_2$ model is $\Delta$. At vanishing chemical potential, we observe restoration of chiral symmetry at high $T$. In low temperature and high chemical potential region, we find existence of inhomogeneous phase in spatial correlation functions of $\sigma$ and $\pi$. The signal of inhomogeneous phase in correlation function of $\Delta$ is more clearly than that of $\sigma$ or $\pi$.

   hep-latnucl-thPoS(2022)·12 citations
6. 06*

   Finite temperature QCD with physical $(u/d,s,c)$ domain-wall quarks

   Yu-Chih Chen🇹🇼 · Ting-Wai Chiu🇹🇼 · Tung-Han Hsieh🇹🇼

   In order to understand the role of QCD in the early universe, we perform hybrid Monte-Carlo simulation of lattice QCD with $N_f=2+1+1$ optimal domain-wall quarks at the physical point, on the $64^3\times (6,8,10,12,16,20,64)$ lattices, each with three lattice spacings. The lattice spacings and the bare quark masses are determined on the $64^4$ lattices. The resulting gauge ensembles provide a basis for studying finite temperature QCD with $N_f=2+1+1$ domain-wall quarks at the physical point. In this Proceeding, we present our first result on the topological susceptibility of the QCD vacuum. The topological charge of each gauge configuration is measured by the clover charge in the Wilson flow at the same flow time in physical units, and the topological susceptibility ${\chi }_t(a,T)$ is determined for each ensemble with lattice spacing $a$ and temperature $T$. Using the topological susceptibility ${\chi }_t(a,T)$ of 15 gauge ensembles with three lattice spacings and different temperatures in the range $T\sim 155-516$~MeV, we extract the topological susceptibility ${\chi }_t(T)$ in the continuum limit.

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

   Lattice QCD noise reduction for bosonic correlators through blocking

   Luis Altenkort🇩🇪 · Alexander M. Eller🇩🇪 · O. Kaczmarek🇩🇪 · Lukas Mazur🇩🇪 · Guy D. Moore🇩🇪 · H.-T. Shu🇩🇪

   We propose a method to substantially improve the signal-to-noise ratio of lattice correlation functions for bosonic operators or other operator combinations with disconnected contributions. The technique is applicable for correlations between operators on two planes (zero momentum correlators) when the dimension of the plane is larger than the separation between the two planes which are correlated. In this case, the correlation arises primarily from points whose in-plane coordinates are close, but noise arises from all pairs of points. By breaking each plane into bins and computing bin-bin correlations, it is possible to capture these short-distance correlators exactly while replacing (small) correlators at large spatial extent with a fit, with smaller uncertainty than the data. The cost is only marginally larger than averaging each plane before correlating, but the improvement in signal-to-noise can be substantial. We test the method on correlators of the gradient-flowed topological charge density and squared field strength, finding noise reductions by a factor of $\sim$ 3$-$7 compared to the conventional approach on the same ensemble of configurations.

   hep-latcond-mat.stat-mechnucl-thphysics.comp-phPRD(2022)·7 citations
8. 08*

   Quantifying corrections to the hadron resonance gas with lattice QCD

   Rene Bellwied🇺🇸 · Szabolcs Borsányi🇩🇪 · Zoltán Fodor🇩🇪 · Jana N. Guenther🇫🇷 · Sándor D. Katz🇭🇺 · Paolo Parotto🇩🇪 · Attila Pásztor🇭🇺 · Dávid Pesznyák🇭🇺 · Claudia Ratti🇺🇸 · Kálmán K. Szabó🇩🇪

   The hadron resonance gas (HRG) model and its extensions are often used to describe the hadronic phase of strongly interacting matter. In our work we use lattice-QCD simulations with temporal extents of $N_{\tau }=8,10$ and $12$ to quantify corrections to the ideal HRG. Firstly, we determine a number of subleading fugacity expansion coefficients of the QCD free energy via a two-dimensional scan on the imaginary baryon number chemical potential (${\mu }_B$) - strangeness chemical potential (${\mu }_S$) plane. Using the aforementioned coefficients, we also extrapolate ratios of baryon number and strangeness fluctuations and correlations to finite chemical potentials via a truncated fugacity expansion. Our results extrapolated along the crossover line $T_{\mathrm{c}}({\mu }_B)$ at strangeness neutrality are able to reproduce trends of experimental net-proton fluctuations measured by the STAR Collaboration.

   hep-latPoS(2022)·2 citations
9. 09*

   Multi-level computation of the hadronic vacuum polarization contribution to $(g_{\mu }-2)$

   Leonardo Giusti🇮🇹 · Mattia Dalla Brida🇨🇭 · Tim Harris🇬🇧 · Michele Pepe🇮🇹

   The first results from the Fermilab E989 experiment have confirmed the long-standing tension between the experimental determination of the muon anomalous magnetic moment $a_{\mu }=(g_{\mu }-2)/2$ and its SM determination using the dispersive approach. In order to match the expected final precision from E989, the current uncertainty on ab initio determinations using lattice QCD must be decreased by a factor 5-15, a goal which is hampered by the signal-to-noise ratio problem of the electromagnetic current correlator. Multi-level Monte Carlo integration with fermions is a method which reduces the variance of correlators exponentially in the distance of the fields. Here we demonstrate that the variance reduction in a realistic two-level simulation with a pion mass of 270 MeV, linear size of 3 fm and lattice spacing around 0.065 fm is sufficient to compute the tail of the current correlator with the statistical accuracy required for the hadronic vacuum polarization contribution to $a_{\mu }$. An efficient estimator is also employed for computing the disconnected contribution.

   hep-latPoS(2022)·4 citations
10. 10*

    Complex Langevin boundary terms in lattice models

    Michael W. Hansen🇦🇹 · Erhard Seiler🇩🇪 · Dénes Sexty🇦🇹 · Ion-Olimipu Stamatescu🇩🇪

    In complex Langevin simulations, the insufficient decay of the probability density near infinity leads to boundary terms that spoil the formal argument for correctness. We present a formulation of this term that is cheaply measurable in lattice models, and in principle allows also the direct estimation of the systematic error of the CL method. Results for a toy model, 3d XY model and HDQCD are presented.

    hep-latPoS(2022)·2 citations
11. 11*

    Topology in high-$T$ QCD via staggered spectral projectors

    Andreas Athenodorou🇨🇾 · Claudio Bonanno🇮🇹 · Claudio Bonati🇮🇹 · Giuseppe Clemente🇩🇪 · Francesco D'Angelo🇮🇹 · Massimo D'Elia🇮🇹 · Lorenzo Maio🇮🇹 · Guido Martinelli🇮🇹 · Francesco Sanfilippo🇮🇹 · Antonino Todaro🇨🇾

    We present preliminary lattice results for the topological susceptibility in high-$T$ $N_f=2+1$ QCD obtained discretizing this observable via spectral projectors on eigenmodes of the staggered operator, and we compare them with those obtained with the standard gluonic definition. The adoption of the spectral discretization is motivated by the large lattice artifacts affecting the continuum scaling of the gluonic susceptibility at high $T$, related to the choice of non-chiral fermions in the action.

    hep-latPoS(2022)·1 citation
12. 12*

    Properties of Overlap and Domain Wall Fermions in the 2+1D Thirring Model

    Jude Worthy🇬🇧 · Simon Hands🇬🇧

    We present some results pertaining to partially quenched formulations of the overlap/domain wall operator with the Thirring model in 2+1D. Auxiliary fields are generated with a Shamir domain wall approach and measurements of eigenvalues and condensates are contrasted with different overlap operators. The numerical challenge posed by a non-compact formulation is highlighted, and the effective use of lower accuracy sea fermions is demonstrated.

    hep-latPoS(2022)·2 citations
13. 13*

    Charmed semileptonics with twisted-mass valence quarks

    Julien Frison🇩🇪 · Gregorio Herdoiza🇪🇸 · Carlos Pena🇪🇸 · Jose Angel Romero🇪🇸 · Javier Ugarrio🇪🇸

    Our charm program uses a mixed action with twisted-mass valence quarks over non-perturbatively improved Wilson sea quarks, in order to study various quantities in a relativistic and manifestly local framework of full QCD. The sea sector consists of $N_{\mathrm{f}}=2+1$ ensembles generated by the CLS initiative. Taking advantage of open boundary conditions, this allows access to fine ensembles without topological freezing. Here we focus in particular on our current progress on $D\to K\nu l$ and $D\to \pi \nu l$ semileptonics. Those are first and foremost useful for the computation of the CKM matrix elements $|V_{cs}|$ and $|V_{cd}|$. We show that all discretisation effects seem to be reasonably under control with this choice of action, in particular those related to hypercubic lattice artefacts. Eventually, we obtain preliminary results of the form factors as a very smooth curve on the whole range of momentum transfer, and in particular the signal at zero $q^2$ appears to have the potential to be competitive with earlier published results.

    hep-latPoS(2022)·4 citations
14. 14*

    First Glimpse into the Kaon Gluon Parton Distribution Using Lattice QCD

    Alejandro Salas-Chavira🇺🇸 · Zhouyou Fan🇺🇸 · Huey-Wen Lin🇺🇸

    In this work, we present the first results on the gluon parton distribution of the kaon from lattice quantum chromodynamics. We carry out the lattice calculation at pion mass around 310~MeV and two lattice spacings, 0.15 and 0.12~fm, using $2+1+1$-flavor HISQ ensembles generated by MILC Collaboration. The kaon correlators are calculated using clover fermions and momentum-smearing sources with maximum boost momentum around 2~GeV and high statistics (up to 324,000 measurements). We study the dependence of the resulting reduced Ioffe-time pseudo-distributions at multiple boost momenta and lattice spacings. We then extract the kaon gluon distribution function in the $\overline{\text{MS}}$ scheme at $\mu =2$~GeV, neglecting the mixing between the gluon and singlet-quark sectors. Our results at the smaller lattice spacing are consistent with phenomenological determinations.

    hep-lathep-phnucl-thPRD(2022)·49 citations
15. 15*

    Coupling Yang-Mills with Causal Dynamical Triangulations

    Alessandro Candido🇮🇹 · Giuseppe Clemente🇳🇱 · Massimo D'Elia🇮🇹 · Federico Rottoli🇮🇹

    We discuss the algorithmic problem of minimal coupling gauge fields of the Yang-Mills type to Quantum Gravity in the approach known as Causal Dynamical Triangulations (CDT) as a step towards studying, ultimately, systems of gravity coupled with bosonic and fermionic matter. We first describe the algorithm for general dimensions and gauge groups and then focus on the results obtained from simulations of 2d CDT coupled to gauge fields with U{(1)} and SU{(2)} gauge groups, where we studied both observables related to gravity and gauge fields, and compared them with analogous simulations in the static flat case.

    hep-latgr-qchep-thPoS(2022)·0 citations
16. 16*

    Quantum error mitigation for parametric circuits

    Vasily Sazonov🇫🇷 · Mohamed Tamaazousti🇫🇷

    Reducing errors is critical to the application of modern quantum computers. In the current Letter, we investigate the quantum error mitigation considering parametric circuits accessible by classical computations in some range of their parameters. We present a method of global randomized error cancellations (GREC) mitigating quantum errors by summing a linear combination of additionally randomized quantum circuits with weights determined by comparison with the referent classically computable data. We illustrate the performance of this method on the example of the $n=4$ spins anti-ferromagnetic Ising model in the transverse field.

    ↳ quant-phhep-latPRA(2022)·3 citations
17. 17*

    Octet and decuplet baryon $\sigma$-terms and mass decompositions

    P. M. Copeland🇺🇸 · Chueng-Ryong Ji🇺🇸 · W. Melnitchouk🇺🇸

    We present a comprehensive analysis of the SU(3) octet and decuplet baryon masses and $\sigma$-terms using high-precision lattice QCD data and chiral SU(3) effective theory with finite range regularization. The effects of various systematic uncertainties, including from the scale setting of the lattice data and the regularization prescriptions, are quantified. We find the pion-nucleon and strange nucleon $\sigma$-terms to be ${\sigma }_{\pi N}=44(3)(3)$ MeV and ${\sigma }_{Ns}=50(6)(1)$ MeV, respectively. The results provide constraints on the energy-momentum tensor mass decompositions of the SU(3) octet and decuplet baryons, where we find the trace anomaly and quark/gluon energies decrease for strange baryons due to their larger strange $\sigma$-terms.

    ↳ nucl-thhep-lathep-phPRD(2023)·10 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.