Mon·Oct 17, 2022Monday·October 17, 2022

1. 01*

   Towards glueball masses of large-$N\mathrm{SU}(N)$ Yang-Mills theories without topological freezing via parallel tempering on boundary conditions

   Claudio Bonanno🇮🇹 · Massimo D'Elia🇮🇹 · Biagio Lucini🇬🇧 · Davide Vadacchino🇬🇧

   Standard local updating algorithms experience a critical slowing down close to the continuum limit, which is particularly severe for topological observables. In practice, the Markov chain tends to remain trapped in a fixed topological sector. This problem further worsens at large $N$, and is known as $topologicalfreezing$. To mitigate it, we adopt the parallel tempering on boundary conditions proposed by M. Hasenbusch. This algorithm allows to obtain a reduction of the auto-correlation time of the topological charge up to several orders of magnitude. With this strategy we are able to provide the first computation of low-lying glueball masses at large $N$ free of any systematics related to topological freezing.

   hep-lathep-phhep-thPoS(2023)·7 citations
2. 02*

   Thermal Transitions in Dense Two-Colour QCD

   Dale Lawlor🇮🇪 · Simon Hands🇬🇧 · Seyong Kim🇰🇷 · Jon-Ivar Skullerud🇮🇪

   The infamous sign problem makes it impossible to probe dense (baryon density ${\mu }_B>0$) QCD at temperatures near or below the deconfinement threshold. As a workaround, one can explore QCD-like theories such as two-colour QCD (QC2D) which don't suffer from this sign problem but are qualitively similar to real QCD. Previous studies on smaller lattice volumes have investigated deconfinement and colour superfluid to normal matter transitions. In this study we look at a larger lattice volume $N_s=24$ in an attempt to disentangle finite volume and finite temperature effects. We also fit to a larger number of diquark sources to better allow for extrapolation to zero diquark source.

   hep-lathep-phnucl-thEPJ Web Conf.(2022)·3 citations
3. 03*

   A stabilizing kernel for complex Langevin simulations of real-time gauge theories

   Kirill Boguslavski🇦🇹 · Paul Hotzy🇦🇹 · David I. Müller🇦🇹

   The complex Langevin (CL) method is a promising approach to overcome the sign problem, which emerges in real-time formulations of quantum field theories. Over the past decade, stabilization techniques for CL have been developed with important applications in finite density QCD. However, they are insufficient for SU($N_c$) gauge theories on a Schwinger-Keldysh time contour that is required for a real-time formulation. In these proceedings we revise the discretization of the real-time CL equations and introduce a novel anisotropic kernel that enables CL simulations on discretized time contours. Applying it to SU(2) Yang-Mills theory in 3+1 dimensions, we obtain unprecedentedly stable results that may allow us to calculate real-time observables from first principles.

   hep-lathep-phPoS(2023)·5 citations
4. 04*

   Constraint Inequalities from Hilbert Space Geometry & Efficient Quantum Computation

   Chinonso Onah

   Useful relations describing arbitrary parameters of given quantum systems can be derived from simple physical constraints imposed on the vectors in the corresponding Hilbert space. This is well known and it usually proceeds by partitioning the large dimensional Hilbert space into relevant sub spaces and relating points in the Hilbert space to the expectation values of physical observables. The aim of this note is quite modest. We describe the procedure and point out that this parallels the necessary considerations that make Quantum Simulation of quantum fields and interacting many body quantum systems on Noisy Intermediate Scale Quantum (NISQ) devices possible. We conclude by pointing out relevant parts of Quantum Computing where these ideas could be useful. This work proceeds in density matrix formalism and is a review of materials found in references. We enrich the literature by suggesting how to use these ideas to guide and improve parameterized quantum circuits.

   ↳ quant-phhep-latphysics.comp-ph0 citations
5. 05*

   Schwinger-Dyson truncations in the all-soft limit: a case study

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

   We study a special Schwinger-Dyson equation in the context of a pure SU(3) Yang-Mills theory, formulated in the background field method. Specifically, we consider the corresponding equation for the vertex that governs the interaction of two background gluons with a ghost-antighost pair. By virtue of the background gauge invariance, this vertex satisfies a naive Slavnov-Taylor identity, which is not deformed by the ghost sector of the theory. In the all-soft limit, where all momenta vanish, the form of this vertex may be obtained exactly from the corresponding Ward identity. This special result is subsequently reproduced at the level of the Schwinger-Dyson equation, by making extensive use of Taylor's theorem and exploiting a plethora of key relations, particular to the background field method. This information permits the determination of the error associated with two distinct truncation schemes, where the potential advantage from employing lattice data for the ghost dressing function is quantitatively assessed.

   ↳ hep-phhep-lathep-thnucl-thEPJC(2022)·6 citations
6. 06*

   On the quark spectral function in QCD

   Jan Horak🇩🇪 · Jan M. Pawlowski🇩🇪 · Nicolas Wink🇩🇪

   We calculate the spectral function of light quark flavours in 2+1 flavour vacuum QCD in the isospin-symmetric approximation. We employ spectral Dyson-Schwinger equations and compute the non-perturbative quark propagator directly in real-time, using recent spectral reconstruction results from Gaussian process regression of gluon propagator data in 2+1 flavour lattice QCD. Our results feature a pole-like peak structure at time-like momenta larger than the propagator's gapping scale as well as a negative scattering continuum, which we exploit assuming an analytic pole-tail split during the iterative solution. The computation is augmented with a general discussion of the impact of the quark-gluon vertex and the gluon propagator on the analytic structure of the quark propagator. In particular, we investigate under which conditions the quark propagator shows unphysical complex poles. Our results offer a wide range of applications, encompassing the ab-initio calculation of transport as well as resonance properties in QCD.

   ↳ hep-phhep-lathep-thSciPost Phys.(2023)·34 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.