Wed·Nov 30, 2022Wednesday·November 30, 2022

1. 01*

   Log-enhanced discretization errors in integrated correlation functions

   Leonardo Chimirri🇩🇪 · Nikolai Husung🇬🇧 · Rainer Sommer🇩🇪

   Integrated time-slice correlation functions $G(t)$ with weights $K(t)$ appear, e.g., in the moments method to determine ${\alpha }_s$ from heavy quark correlators, in the muon g-2 determination or in the determination of smoothed spectral functions. For the (leading-order-)normalised moment $R_4$ of the pseudo-scalar correlator we have non-perturbative results down to $a=10^{-2}$ fm and for masses, $m$, of the order of the charm mass in the quenched approximation. A significant bending of $R_4$ as a function of $a^2$ is observed at small lattice spacings. Starting from the Symanzik expansion of the integrand we derive the asymptotic convergence of the integral at small lattice spacing in the free theory and prove that the short distance part of the integral leads to $\log (a)$-enhanced discretisation errors when $G(t)K(t)\sim t$ for small $t$. In the interacting theory an unknown, function $K(a\Lambda )$ appears. For the $R_4$-case, we modify the observable to improve the short distance behavior and demonstrate that it results in a very smooth continuum limit. The strong coupling and the $\Lambda$-parameter can then be extracted. In general, and in particular for $g-2$, the short distance part of the integral should be determined by perturbation theory. The (dominating) rest can then be obtained by the controlled continuum limit of the lattice computation.

   hep-lathep-phPoS(2023)·15 citations
2. 02*

   Inclusion of heavy spin effects in the $ud\bar{b}\bar{b}$ $I(J^P)=0(1^{-})$ four-quark channel in the Born-Oppenheimer approximation

   Jakob Hoffmann🇩🇪 · André Zimermmane-Santos🇩🇪 · Marc Wagner🇩🇪

   We refine our previous study of a $ud\bar{b}\bar{b}$ tetraquark resonance with quantum numbers $I(J^P)=0(1^{-})$, which is based on antiheavy-antiheavy lattice QCD potentials, by including heavy quark spin effects via the mass difference of the $B$ and the $B^{\ast }$ meson. This leads to a coupled channel Schrödinger equation, where the two channels correspond to $BB$ and $B^{\ast }{B}^{\ast }$, respectively. We search for $\text{mbox}T$ matrix poles in the complex energy plane, but do not find any indication for the existence of a tetraquark resonance in this refined coupled channel approach. We also vary the antiheavy-antiheavy potentials as well as the $b$ quark mass to further understand the dynamics of this four-quark system.

   hep-lathep-phPoS(2023)·10 citations
3. 03*

   Isovector nucleon form factors from 2+1-flavor dynamical domain-wall lattice QCD at the physical mass

   Shigemi Ohta (KEK, for the LHP, RBC, and UKQCD Collaborations)🇯🇵

   Nucleon isovector form factors calculated on a 2+1-flavor domain-wall-fermions ensemble with strange and degenerate up and down quarks at physical mass and lattice cut off, $a^{-1}$, of about 1.730(4) GeV, are reported. The ensemble was generated jointly by RBC and UKQCD collaborations with a spatial extent of $48a$ or about 5.5 fm. The form factors are calculated in collaboration with LHP collaboration as well. The resulting shape parameters of the form factors, such as vector-charge mean squared radius, $⟨r_1^2⟩$, or anomalous magnetic moment, $F_2(0)$ appear less dependent on possible excited-state contaminations than the corresponding charges. Preliminary estimates are $⟨r_1^2⟩\sim 0.142(13)\text{mbox}{fm}^2$ and $F_2(0)\sim 3.22(8)$.

   hep-latPoS(2023)·3 citations
4. 04*

   Probing singularities of Landau-gauge propagators with Padé approximants

   Cristiane Y. London🇧🇷 · Diogo Boito🇧🇷 · Attilio Cucchieri🇧🇷 · Tereza Mendes🇧🇷

   Padé approximants are employed in order to study the analytic structure of the four-dimensional SU(2) Landau-gauge gluon and ghost propagators in the infrared regime. The approximants, which are model independent, are used as fitting functions to lattice data for the propagators, carefully propagating uncertainties due to the fit procedure and taking into account all possible correlations. Applying this procedure systematically to the gluon-propagator data, we observe the presence of a pair of complex poles at $p_{\mathrm{pole}}^2=(-0.37\pm 0.05_{\mathrm{stat}}\pm 0.08_{\mathrm{sys}})\pm i(0.66\pm 0.03_{\mathrm{stat}}\pm 0.02_{\mathrm{sys}}){\mathrm{GeV}}^2$, where ``stat'' represents the statistical error and ``sys'' the systematic one. We also find a zero on the negative real axis of $p^2$, at $p_{\mathrm{zero}}^2=(-2.9\pm 0.4_{\mathrm{stat}}\pm 0.9_{\mathrm{sys}}){\mathrm{GeV}}^2$. We thus note that our procedure -- which is based on a model-independent approach and includes careful error propagation -- confirms the presence of a pair of complex poles in the gluon propagator, in agreement with previous works. For the ghost propagator, the Padés indicate the existence of the single pole at $p^2=0$, as expected. We also find evidence of a branch cut on the negative real axis. Through the use of the so-called D-Log Padé method, which is designed to approximate functions with cuts, we corroborate the existence of this cut for the ghost propagator.

   hep-lathep-phPoS(2023)·0 citations
5. 05*

   A machine learning approach to the classification of phase transitions in many flavor QCD

   Frithjof Karsch🇩🇪 · Anirban Lahiri🇩🇪 · Marius Neumann🇩🇪 · Christian Schmidt🇩🇪

   Normalizing flows are generative machine learning models which can efficiently approximate probability distributions, using only given samples of a distribution. This architecture is used to interpolate the chiral condensate obtained from QCD simulations with five degenerate quark flavors in the HISQ action. From this a model for the probability distribution of the chiral condensate as function of lattice volume, quark mass and gauge coupling is obtained. Using the model, first order and crossover regions can be classified and the boundary between these regions can be marked by a critical mass. An extension of this model to studies of phase transitions in QCD with variable number of flavors is expected to be possible.

   hep-lathep-phPoS(2023)·9 citations
6. 06*

   Persistent homology as a probe for center vortices and deconfinement in SU(2) lattice gauge theory

   Nicholas Sale🇬🇧 · Biagio Lucini🇬🇧 · Jeffrey Giansiracusa🇬🇧

   Topological Data Analysis (TDA) is a field that leverages tools and ideas from algebraic topology to provide robust methods for analysing geometric and topological aspects of data. One of the principal tools of TDA, persistent homology, produces a quantitative description of how the connectivity and structure of data changes when viewed over a sequence of scales. We propose that this presents a means to directly probe topological objects in gauge theories. We present recent work on using persistent homology to detect center vortices in SU(2) lattice gauge theory configurations in a gauge-invariant manner. We introduce the basics of persistence, describe our construction, and demonstrate that the result is sensitive to vortices. Moreover we discuss how, with simple machine learning, one can use the resulting persistence to quantitatively analyse the deconfinement transition via finite-size scaling, providing evidence on the role of vortices in relation to confinement in Yang-Mills theories.

   hep-latPoS(2023)·0 citations
7. 07*

   Performance Optimization of Baryon-block Construction in the Stochastic LapH Method

   Phuong Nguyen🇩🇪 · Ben Hörz🇩🇪

   Implementations of measurement kernels in high-level Lattice QCD frameworks enable rapid prototyping, but can leave hardware capabilities significantly underutilized. This is an acceptable tradeoff if the time spent in unoptimized routines is generally small. The computational cost of modern spectroscopy projects however can be comparable to or even exceed the cost of generating gauge configurations and computing solutions of the Dirac equation. One such key kernel in the stochastic LapH method is the computation of baryon blocks; we discuss several implementation strategies and achieve a 7.2x speedup over the current implementation on a system with Intel(R) Xeon(R) Platinum 8358 processors, formerly Ice Lake.

   hep-latPoS(2023)·0 citations
8. 08*

   Precision Studies of QCD in the Low Energy Domain of the EIC

   V. Burkert · L. Elouadrhiri · A. Afanasev · J. Arrington · M. Contalbrigo · W. Cosyn · A. Deshpande · D. Glazier · X. Ji · S. Liuti · Y. Oh · D. Richards · T. Satogata · A. Vossen

   The manuscript focuses on the high impact science of the EIC with objective to identify a portion of the science program for QCD precision studies that requires or greatly benefits from high luminosity and low center-of-mass energies. The science topics include (1) Generalized Parton Distributions, 3D imagining and mechanical properties of the nucleon (2) mass and spin of the nucleon (3) Momentum dependence of the nucleon in semi-inclusive deep inelastic scattering (4) Exotic meson spectroscopy (5) Science highlights of nuclei (6) Precision studies of Lattice QCD in the EIC era (7) Science of far-forward particle detection (8) Radiative effects and corrections (9) Artificial Intelligence (10) EIC interaction regions for high impact science program with discovery potential. This paper documents the scientific basis for supporting such a program and helps to define the path toward the realization of the second EIC interaction region.

   ↳ nucl-exhep-exhep-lathep-ph+1PPNP(2023)·95 citations
9. 09*

   Patterns of gauge symmetry in the background field method

   A. C. Aguilar🇧🇷 · M. N. Ferreira🇪🇸 · D. Ibañez🇪🇸 · B. M. Oliveira🇧🇷 · J. Papavassiliou🇪🇸

   The correlation functions of Yang-Mills theories formulated in the background field method satisfy linear Slavnov-Taylor identities, which are naive generalizations of simple tree level relations, with no deformations originating from the ghost sector of the theory. In recent years, a stronger version of these identities has been found to hold at the level of the background gluon self-energy, whose transversality is enforced separately for each special block of diagrams contributing to the gluon Schwinger-Dyson equation. In the present work we demonstrate by means of explicit calculations that the same distinct realization of the Slavnov-Taylor identity persists in the case of the background three-gluon vertex. The analysis is carried out at the level of the exact Schwinger-Dyson equation for this vertex, with no truncations or simplifying assumptions. The demonstration entails the contraction of individual vertex diagrams by the relevant momentum, which activates Slavnov-Taylor identities of vertices and multi-particle kernels nested inside these graphs; the final result emerges by virtue of a multitude of extensive cancellations, without the need of performing explicit integrations. In addition, we point out that background Ward identities amount to replacing derivatives of propagators by zero-momentum background-gluon insertions, in exact analogy to standard properties of Abelian gauge theories. Finally, certain potential applications of these results are briefly discussed.

   ↳ hep-thhep-lathep-phnucl-thEPJC(2023)·3 citations
10. 10*

    Dirac Kondo effect under magnetic catalysis

    Koichi Hattori🇨🇳 · Daiki Suenaga🇯🇵 · Kei Suzuki🇯🇵 · Shigehiro Yasui🇯🇵

    We develop a mean-field theory of a novel Kondo effect emerging in systems without a Fermi surface, which instead emerges under strong magnetic fields. We determine the magnitude of the Kondo condensate which is a particle pairing composed of conducting Dirac fermions and localized impurities. We focus on the competition between the Kondo effect and the energy gap formation that stems from the pairing among the Dirac fermions leading to the dynamical chiral symmetry breaking. We find that this competition induces a quantum critical point. We also investigate finite-temperature effects. This system at vanishing fermion density can be studied with Monte Carlo lattice simulations which do not suffer from the sign problem.

    ↳ hep-phcond-mat.mes-hallcond-mat.str-elhep-lat+1PRB(2023)·4 citations
11. 11*

    Cubic fixed point in three dimensions: Monte Carlo simulations of the ${\varphi }^4$ model on the lattice

    Martin Hasenbusch🇩🇪

    We study the cubic fixed point for $N=3$ and $4$ by using finite size scaling applied to data obtained from Monte Carlo simulations of the $N$-component ${\varphi }^4$ model on the simple cubic lattice. We generalize the idea of improved models to a two-parameter family of models. The two-parameter space is scanned for the point, where the amplitudes of the two leading corrections to scaling vanish. To this end, a dimensionless quantity is introduced that monitors the breaking of the $O(N)$-invariance. For $N=4$, we determine the correction exponents ${\omega }_1=0.763(24)$ and ${\omega }_2=0.082(5)$. In the case of $N=3$, we obtain $Y_4=0.0142(6)$ for the RG-exponent of the cubic perturbation at the $O(3)$-invariant fixed point, while the correction exponent ${\omega }_2=0.0133(8)$ at the cubic fixed point. Simulations close to the improved point result in the estimates $\nu =0.7202(7)$ and $\eta =0.0371(2)$ of the critical exponents of the cubic fixed point for $N=4$. For $N=3$, at the cubic fixed point, the $O(3)$-symmetry is only mildly broken and the critical exponents differ only by little from those of the $O(3)$-invariant fixed point. We find $-0.00001⪅{\eta }_{cubic}-{\eta }_{O(3)}⪅0.00007$ and ${\nu }_{cubic}-{\nu }_{O(3)}=-0.00061(10)$.

    ↳ cond-mat.stat-mechhep-lathep-thPRB(2023)·27 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.