Fri·Dec 23, 2022Friday·December 23, 2022

1. 01*

   Towards Quantum Monte Carlo Simulations at non-zero Baryon and Isospin Density in the Strong Coupling Regime

   Pratitee Pattanaik🇩🇪 · Wolfgang Unger🇩🇪

   The Hamiltonian formulation of Lattice QCD with staggered fermions in the strong coupling limit has no sign problem at non-zero baryon density and allows for Quantum Monte Carlo simulations. We have extended this formalism to two flavors, and after a resummation, there is no sign problem both for non-zero baryon and isospin chemical potential. We report on recent progress on the implementation of the Quantum Monte Carlo simulations.

   hep-latPoS(2023)·5 citations
2. 02*

   Use of Schwinger-Dyson equation in constructing an approximate trivializing map

   Peter Boyle🇺🇸 · Taku Izubuchi🇺🇸 · Luchang Jin🇺🇸 · Chulwoo Jung🇺🇸 · Christoph Lehner🇩🇪 · Nobuyuki Matsumoto🇺🇸 · Akio Tomiya🇯🇵

   We construct an approximate trivializing map by using a Schwinger-Dyson equation. The advantage of this method is that: (1) The basis for the flow kernel can be chosen arbitrarily by hand. (2) It can be applied to the general action of interest. (3) The coefficients in the kernel are determined by lattice estimates of the observables, which does not require analytic calculations beforehand. We perform the HMC with the effective action obtained by the Schwinger-Dyson method, and show that we can have better control of the effective action than the known $t$-expansion construction. However, the algorithmic overhead is still large and overwhelming the gain though faster decorrelation is observed for long-range observables in some cases. This contribution reports the preliminary results of this attempt.

   hep-latPoS(2023)·11 citations
3. 03*

   Toward Exploring Phase Diagrams of Gauge Theories on Quantum Computers with Thermal Pure Quantum States

   Zohreh Davoudi🇺🇸 · Niklas Mueller🇺🇸 · Connor Powers🇺🇸

   Aiming at evading the notorious sign problem in classical Monte-Carlo approaches to lattice quantum chromodynamics, we present an approach for quantum computing finite-temperature lattice gauge theories at non-zero density. Based on the thermal pure-quantum-state formalism of statistical mechanics when extended to gauge-theory systems, our approach allows for sign-problem-free quantum computations of thermal expectation values and non-equal time correlation functions. By taking a simple lattice gauge theory for which classical benchmarks are possible, namely ${\mathbb{Z}}_2$ lattice gauge theory in 1+1 dimensions at finite chemical potential, we discuss resource requirements and robustness to algorithmic and hardware imperfections for near-term quantum-hardware realizations.

   hep-lathep-phquant-phPoS(2023)·3 citations
4. 04*

   Gluon PDF for the proton using the twisted mass formulation of lattice QCD

   Joseph Delmar🇺🇸 · Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾

   We present results of the x-dependence of the unpolarized gluon PDF for the proton. We use an $N_f=2+1+1$ ensemble of maximally twisted mass fermions with clover improvement and the Iwasaki improved gluon action. The quark masses are tuned so that the pion mass is 260 MeV. We use a $32^3\times 64$ lattice size with a lattice spacing $a=0.093$ fm giving a spatial extent of 3 fm. We employ the pseudo-distribution approach and obtain the light-cone Ioffe time distribution (ITD) combining data for nucleon momentum boosts up to 1.67 GeV and Wilson line lengths, $z$, up to 0.56 fm. We explore systematic effects such as the dependence on the maximum value of $z$ entering the fits to obtain the gluon PDF.

   hep-lathep-thnucl-thPoS(2023)·3 citations
5. 05*

   Photon production rate from Transverse-Longitudinal ($T-L$) mesonic correlator on the lattice

   Dibyendu Bala🇩🇪 · Sajid Ali🇩🇪 · Anthony Francis🇹🇼 · Greg Jackson🇺🇸 · Olaf Kaczmarek🇩🇪 · Tristan Ueding🇩🇪

   Thermal photons from the QGP provide important information about the interaction among plasma constituents. The photon production rate from a thermally equilibrated system is proportional to the transverse spectral function ${\rho }_T(\omega =|\vec{k}|,\vec{k})$. One can also calculate the photon production rate from the difference between ${\rho }_T(\omega ,\vec{k})$ (transverse) and ${\rho }_L(\omega ,\vec{k})$ (longitudinal) projections, as ${\rho }_L$ vanishes on the photon point. Because the UV part of ${\rho }_T-{\rho }_L$ is suppressed, the corresponding Euclidean correlator receives most of its contribution from the IR part. We calculate the $T-L$ correlator on $N_f=2+1$ flavour HISQ configurations with $m_l=m_s/5$ at temperature of about $1.15T_{pc}$ (220 MeV). We have used two ansätze for the spectral function: 1) A polynomial connected to the UV region consistent with OPE expansion and 2) a hydro-inspired spectral function. We have also applied the Backus-Gilbert method to estimate the spectral function. All these different approaches are combined to estimate the photon production rate.

   hep-lathep-phPoS(2023)·4 citations
6. 06*

   Hadronic vacuum polarization with C* boundary conditions

   Anian Altherr🇨🇭 · Roman Gruber🇨🇭 · Lucius Bushnaq🇮🇪 · Isabel Campos🇪🇸 · Marco Catillo🇨🇭 · Alessandro Cotellucci🇩🇪 · Madeleine Dale🇩🇪 · Patrick Fritzsch🇮🇪 · Javad Komijani🇨🇭 · Jens Lücke🇩🇪 · Marina Krstić Marinković🇨🇭 · Sofie Martins🇩🇰 and 3 other authors

   We present a progress report on the calculation of the connected hadronic contribution to the muon g-2 with C* boundary conditions. For that purpose we use a QCD gauge ensemble with 3+1 flavors and two QCD+QED gauge ensembles with 1+2+1 flavors of dynamical quarks generated by the RC* collaboration. We detail the calculation of the vector mass and elaborate on both statistical and systematic errors.

   hep-latPoS(2023)·5 citations
7. 07*

   Curved domain-wall fermion and its anomaly inflow

   Shoto Aoki🇯🇵 · Hidenori Fukaya🇯🇵

   We investigate the effect of $U(1)$ gauge field on lattice fermion systems with a curved domain-wall mass term. In the same way as the conventional flat domain-wall fermion, the chiral edge modes appear localized at the wall, whose Dirac operator contains the induced gravitational potential as well as the $U(1)$ vector potential. In the case of $S^1$ domain-wall fermion on a two-dimensional flat lattice, we find a competition between the Aharonov-Bohm(AB) effect and gravitational gap in the Dirac eigenvalue spectrum, which leads to anomaly of the time-reversal ($T$) symmetry. Our numerical result shows a good consistency with the Atiyah-Patodi-Singer index theorem on a disk inside the $S^1$ domain-wall, which describes the cancellation of the $T$ anomaly between the bulk and edge. When the $U(1)$ flux is squeezed inside one plaquette, and the AB phase takes a quantized value $\pi$ mod $2\pi \mathbb{Z}$, the anomaly inflow drastically changes: the strong flux creates another domain-wall around the flux to make the two zero modes coexist. This phenomenon is also observed in the $S^2$ domain-wall fermion in the presence of a magnetic monopole. We find that the domain-wall creation around the monopole microscopically explains the Witten effect.

   hep-latcond-mat.mes-hallhep-thPTEP(2023)·26 citations
8. 08*

   Supersphere non-linear sigma model on the lattice

   Ilaria Costa🇩🇪 · Valentina Forini🇬🇧 · Ben Hoare🇬🇧 · Tim Meier🇩🇪 · Agostino Patella🇩🇪 · Johannes Heinrich Weber🇩🇪

   Two-dimensional $O(N)$ non-linear sigma models are exactly solvable theories and have many applications, from statistical mechanics to their use as QCD toy models. We consider a supersymmetric extension, the non-linear sigma model on the supersphere~$S^{N+2m-1|2m}\equiv \frac{OSP(N+2m|2m)}{OSP(N+2m-1|2m)}$. We briefly describe its renormalization properties and lattice discretization, and present a strategy for numerical simulations together with some preliminary numerical results.

   hep-lathep-thPoS(2023)·7 citations
9. 09*

   Metadynamics Surfing on Topology Barriers in the Schwinger Model

   Christian Hoelbling🇩🇪 · Timo Eichhorn🇩🇪 · Philip Rouenhoff🇩🇪 · Lukas Varnhorst🇩🇪

   Topological freezing is a well known problem in lattice simulations: with shrinking lattice spacing a transition between topological sectors becomes increasingly improbable, leading to a problematic increase of the autocorrelation time regarding several observables. We present our investigation of metadynamics as a solution for topological freezing in the Schwinger model. Specifically, we take a closer look at the collective variable and its scaling behaviour, visualize the effects of topological freezing and how metadynamics helps in that respect and explore alternatives for a more efficient building process. Possible implications for and differences to four-dimensional SU(3) theory are briefly discussed.

   hep-latPoS(2022)·5 citations
10. 10*

    The pion-nucleon sigma term with $N_f=2+1$ $\mathcal{O}(a)$-improved Wilson fermions

    Andria Agadjanov🇩🇪 · Dalibor Djukanovic🇩🇪 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Konstantin Ottnad🇩🇪 · Hartmut Wittig🇩🇪

    We present an analysis of the pion-nucleon sigma term on the CLS ensembles with $N_f=2+1$ flavors of $\mathcal{O}(a)$-improved Wilson fermions. We perform a chiral interpolation based on ensembles with pion masses ranging from 130 MeV to roughly 350 MeV. The analysis covers four lattice spacings between $a\approx [0.05\mathrm{fm}\dots 0.09\mathrm{fm}]$, allowing for an estimate of systematics associated with lattice artefacts.

    hep-latPoS(2023)·0 citations
11. 11*

    General kinematics of the three-gluon vertex from quenched lattice QCD

    Fernando Pinto-Gómez🇪🇸 · Feliciano de Soto🇪🇸 · Mauricio N. Ferreira🇪🇸 · Joannis Papavassiliou🇪🇸 · José Rodríguez-Quintero🇪🇸

    We present new results for the transversely projected three-gluon vertex from quenched lattice QCD simulations using standard Wilson action. While previous works focused in some particular kinematics such as the symmetric $(q^2=r^2=p^2)$ and soft-gluon $(p=0)$ cases, here we will present a detailed analysis of the bisectoral case $(r^2=q^2\ne p^2)$ where the transversely projected vertex can be cast in terms of three independent tensors. The lattice data show a clear dominance of the form-factor corresponding to the tree-level tensor, whose dependence on the momenta can be almost entirely expressed in terms of the symmetric combination of the momenta $s^2=(q^2+r^2+p^2)/2$.

    hep-lat1 citation
12. 12*

    (Semi)leptonic kaon decays and neutral kaon mixing from lattice QCD

    Takashi Kaneko🇯🇵

    We review recent progress on leptonic and semileptonic kaon decays and neutral kaon mixing from lattice QCD.

    hep-lathep-phJ.Phys.Conf.Ser.(2023)·1 citation
13. 13*

    Density profiles and correlations of harmonically trapped ultracold fermions via complex Langevin

    Felipe Attanasio🇩🇪 · Marc Bauer🇩🇪 · Jan M. Pawlowski🇩🇪

    Standard lattice formulations of non-relativistic Fermi gases with two spin components suffer from a sign problem in the cases of repulsive contact interactions and attractive contact interactions with spin imbalance. We discuss the nature of this sign problem and the applicability of stochastic quantisation with complex Langevin evolution in both cases. For repulsive interactions, we find that the results converge, using adaptive step size scaling and a Gaussian regulator to modify the lattice action. We present results on density profiles and correlations of a harmonically trapped system in one spatial dimension.

    ↳ cond-mat.quant-gascond-mat.str-elhep-latPoS(2023)·4 citations
14. 14*

    Local spatial densities for composite spin-3/2 systems

    H. Alharazin🇩🇪 · B.-D. Sun🇨🇳 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · U.-G. Meißner🇩🇪

    The definition of local spatial densities by using sharply localized one-particle states is applied to spin-3/2 systems. Matrix elements of the electromagnetic current and the energy-momentum tensor are considered and integral expressions of associated spatial distributions in terms of form factors are derived.

    ↳ hep-phhep-exhep-latJHEP(2023)·16 citations
15. 15*

    Polyakov's confinement mechanism for generalized Maxwell theory

    Matthew Heydeman🇺🇸 · Christian B. Jepsen🇺🇸 · Ziming Ji🇮🇹 · Amos Yarom🇮🇱

    We study fractional-derivative Maxwell theory, as appears in effective descriptions of, for example, large $N_f$ QED${}_3$, graphene, and some types of surface defects. We argue that when the theory is UV completed on a lattice, monopole condensation leads to a confining phase via the Polyakov confinement mechanism.

    ↳ hep-thcond-mat.str-elhep-latJHEP(2023)·8 citations
16. 16*

    Precision calculations of $B_{d,s}\to \pi ,K$ decay form factors in soft-collinear effective theory

    Bo-Yan Cui🇨🇳 · Yong-Kang Huang🇨🇳 · Yue-Long Shen🇨🇳 · Chao Wang🇨🇳 · Yu-Ming Wang🇨🇳

    We improve QCD calculations of the $B_{d,s}\to \pi ,K$ form factors at large hadronic recoil by implementing the next-to-leading-logarithmic resummation for the obtained leading-power light-cone sum rules in the soft-collinear effective theory (SCET) framework. Additionally, we endeavour to investigate a variety of the subleading-power contributions to these heavy-to-light form factors at $\mathcal{O}({\alpha }_s^0)$, by including the higher-order terms in the heavy-quark expansion of the hard-collinear quark propagator, by evaluating the desired effective matrix element of the next-to-leading-order term in the $\mathrm{SCE}{\mathrm{T}}_{\mathrm{I}}$ representation of the weak transition current, by taking into account the off-light-cone contributions of the two-body heavy-quark effective theory matrix elements as well as the three-particle higher-twist corrections from the subleading bottom-meson light-cone distribution amplitudes, and by computing the twist-five and twist-six four-body higher-twist effects with the aid of the factorization approximation. Having at our disposal the SCET sum rules for the exclusive $B$-meson decay form factors, we further explore in detail numerical implications of the newly computed subleading-power corrections by employing the three-parameter model for both the leading-twist and higher-twist $B$-meson distribution amplitudes. Taking advantage of the customary Bourrely-Caprini-Lellouch parametrization for the semileptonic $B_{d,s}\to \pi ,K$ form factors, we then determine the correlated numerical results for the interesting series coefficients, by carrying out the simultaneous fit of the exclusive $B$-meson decay form factors to both the achieved SCET sum rule predictions and the available lattice QCD results.

    ↳ hep-phhep-exhep-latJHEP(2023)·66 citations
17. 17*

    Unobservability of the topological charge in nonabelian gauge theory: Ward-Takahashi identity and phenomenological aspects

    Nodoka Yamanaka🇯🇵

    We argue that the topological charge of nonabelian gauge theory is unphysical. To show this statement, we use the Adler-Bardeen theorem and the Becchi-Rouet-Stora-Tyutin symmetry which are warranted by the perturbative finiteness of the chiral anomaly, thus being free of Gribov ambiguity. In addition to the original argument using the unphysical gauge field component collinear to the spatial derivative of the gauge function, we show the unobservability of the topological charge using the Ward-Takahashi identity. We then present the consequences of this finding and show the consistency with many physical pictures and ideas that have been developed around the topology of nonabelian gauge theory. The most important ones are the resolution of the Strong CP problem, the unobservability of topological instantons, the physical relevance of the axial $U(1)$ symmetry, the independence of the vacuum energy on the vacuum angle, and the impossibility to realize the sphaleron induced baryogenesis and chiral magnetic effects. The axial $U(1)$ symmetry and the unphysical $\theta$-term imply that the physical complex phase of the Cabibbo-Kobayashi-Maskawa matrix is the sole source of CP violation in the standard model. The unphysical sphaleron also means that the lepton number is phenomenologically free from the baryon number, and their violations may be modeled separately. We also comment on the consistency with the results of lattice calculations.

    ↳ hep-phhep-lathep-thnucl-th16 citations
18. 18*

    Mesonic "screening masses" in high temperature QCD

    Edward Shuryak🇺🇸

    Lattice studies of QCD at high temperature has investigated the so called ``screening masses", corresponding to quark-antiquark states propagating in $spatial$ (rather than time) direction. Thirty years ago we pointed out that those should correspond to states of 2+1 dimensional quarkonia, and in this work we show that this correspondence provide quantitative description of the lattice data.

    ↳ hep-phhep-lat1 citation
19. 19*

    Free Energy on the Sphere for Non-Abelian Gauge Theories

    Fabiana De Cesare🇮🇹 · Lorenzo Di Pietro🇮🇹 · Marco Serone🇮🇹

    We compute the $S^d$ partition function of the fixed point of non-abelian gauge theories in continuous $d$, using the $ϵ$-expansion around $d=4$. We illustrate in detail the technical aspects of the calculation, including all the factors arising from the gauge-fixing procedure, and the method to deal with the zero-modes of the ghosts. We obtain the result up to NLO, i.e. including two-loop vacuum diagrams. Depending on the sign of the one-loop beta function, there is a fixed point with real gauge coupling in $d>4$ or $d<4$. In the first case we extrapolate to $d=5$ to test a recently proposed construction of the UV fixed point of $5d$ $SU(2)$ Yang-Mills via a susy-breaking deformation of the $E_1$ SCFT. We find that the $F$ theorem allows the proposed RG flow. In the second case we extrapolate to $d=3$ to test whether QCD${}_3$ with gauge group $SU(n_c)$ and $n_f$ fundamental matter fields flows to a CFT or to a symmetry-breaking phase. We find that within the regime with a real gauge coupling near $d=4$ the CFT phase is always favored. For lower values of $n_f$ we compare the average of $F$ between the two complex fixed points with its value at the symmetry-breaking phase to give an upper bound of the critical value $n_f^{\ast }$ below which the symmetry-breaking phase takes over.

    ↳ hep-thcond-mat.str-elhep-latJHEP(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.