Tue·Sep 7, 2021Tuesday·September 7, 2021

1. 01*

   Settling an old story: solution of the Thirring model in thimble regularization

   Francesco Di Renzo🇮🇹 · Kevin Zambello🇮🇹

   Thimble regularisation of lattice field theories has been proposed as a solution to the infamous sign problem. It is conceptually very clean and powerful, but it is in practice limited by a potentially very serious issue: in general many thimbles can contribute to the computation of the functional integrals. Semiclassical arguments would suggest that the fundamental thimble could be sufficient to get the correct answer, but this hypothesis has been proven not to hold true in general. A first example of this failure has been put forward in the context of the Thirring model: the dominant thimble approximation is valid only in given regions of the parameter space of the theory. Since then a complete solution of this (simple) model in thimble regularisation has been missing. In this paper we show that a full solution (taking the continuum limit) is indeed possible. It is possible thanks to a method we recently proposed which de facto evades the need to simulate on many thimbles.

   hep-latPRD(2022)·10 citations
2. 02*

   Light pseudo-scalar meson masses under strong magnetic fields within the SU(3) Nambu-Jona-Lasinio model

   Sidney S. Avancini🇧🇷 · Máximo Coppola🇦🇷 · Norberto N. Scoccola🇦🇷 · Joana C. Sodré🇧🇷

   We calculate the pole masses of pseudoscalar mesons in a strongly magnetized medium within the framework of the SU(3) Nambu-Jona--Lasinio model, using a magnetic field-independent regularization scheme. We employ both a constant and a magnetic field-dependent coupling $G(B)$, the latter being fitted to reproduce lattice QCD results for the pseudocritical chiral transition temperature. Numerical results for the pole masses are obtained for definite parametrizations of the model. For neutral mesons, the use of $G(B)$ provides closer agreement with lattice QCD results, which reveal a decrease of the mass with the external field. On the contrary, charged mesons masses are enhanced by $B$, showing no sign of the non-monotonous behavior found in recent lattice QCD simulations.

   ↳ hep-phhep-latPRD(2021)·34 citations
3. 03*

   Hierarchical Qubit Maps and Hierarchical Quantum Error Correction

   Natalie Klco🇺🇸 · Martin J. Savage🇺🇸

   We consider hierarchically implemented quantum error correction (HI-QEC), in which the fidelities of logical qubits are differentially optimized to enhance the capabilities of quantum devices in scientific applications. By employing qubit representations that propagate hierarchies in simulated systems to those in logical qubit noise sensitivities, heterogeneity in the distribution of physical-to-logical qubits can be systematically structured. For concreteness, we estimate HI-QEC's impact on surface code resources in computing low-energy observables to fixed precision, finding up to $\sim 60\%$ reductions in qubit requirements plausible in early error corrected simulations. Hierarchical qubit maps are also possible without error correction in qubit and qudit systems where fidelities are non-uniform, either unintentionally or by design. Hierarchical optimizations are another element in the co-design process of quantum simulations for nuclear and particle physics.

   ↳ quant-phhep-lathep-phnucl-thPRA(2021)·23 citations
4. 04*

   Characterization of topological insulators based on the electronic polarization with spiral boundary conditions

   Masaaki Nakamura🇯🇵 · Shohei Masuda🇯🇵 · Satoshi Nishimoto🇩🇪

   We introduce the electronic polarization originally defined in one-dimensional lattice systems to characterize two-dimensional topological insulators. The main idea is to use spiral boundary conditions which sweep all lattice sites in one-dimensional order. We find that the sign of the polarization changes at topological transition points of the two-dimensional Wilson-Dirac model (the lattice version of the Bernevig-Hughes-Zhang model) in the same way as in one-dimensional systems. Thus the polarization plays the role of "order parameter" to characterize the topological insulating state and enables us to study topological phases in different dimensions in a unified way.

   ↳ cond-mat.str-elhep-latPRB(2021)·4 citations
5. 05*

   Magnetic dipole moments of the $T_{cc}^{+}$ and $Z_V^{++}$ tetraquark states

   K. Azizi🇮🇷 · U. Özdem🇹🇷

   Inspired by the observation of the doubly charmed state $T_{cc}$ and following theoretical studies on its spectroscopic parameters, we investigate its magnetic dipole moment assigning it the quantum numbers $J^P=1^{+}$ and both the compact diquark-antidiquark and molecular structures in the framework of the light-cone QCD. We also calculate the magnetic dipole moment of the theoretically predicted singly charmed state, $Z_V^{++}$, with two units of electric charge and the quantum numbers $J^P=1^{-}$ in diquark-antidiquark picture. The numerical results are obtained as ${\mu }_{T_{cc}^{+}-Di}=0.66_{-0.23}^{+0.34}{\mu }_N$, ${\mu }_{T_{cc}^{+}-Mol}=0.43_{-0.22}^{+0.23}{\mu }_N$ and ${\mu }_{Z_V^{++}}=3.35_{-0.73}^{+0.89}{\mu }_N$. These results may be checked via other phenomenological approaches. The obtained results may be useful in exact determinations of the natures of these states.

   ↳ hep-phhep-exhep-latPRD(2021)·64 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.