Thu·Aug 19, 2021Thursday·August 19, 2021

1. 01*

   Symmetries of temporal correlators and the nature of hot QCD

   L. Ya. Glozman🇦🇹 · Y. Aoki🇯🇵 · S. Hashimoto🇯🇵 · C. Rohrhofer🇯🇵

   The temperature of the chiral restoration phase transition at 130 MeV as well as the temperature of the center symmetry ("deconfinement") phase transition in a pure glue theory at 300 MeV are two independent temperatures and their interplay determines a structure of different regimes of hot QCD. Given a chiral spin symmetry of the color charge and of the chromoelectric interaction we can conclude from observed symmetries of spatial and temporal correlators of N_F=2 QCD with domain wall Dirac operator at physical quark masses that above the chiral symmetry restoration crossover around T_pc but below rougly 3T_pc there should exist an intermediate regime (the stringy fluid) of hot QCD that is characterized by approximate chiral spin symmetry and where degrees of freedom are chirally symmetric quarks bound into color singlet objects by the chromoelectric field. Above this intermediate regime the color charge and the chromoelectric field are Debye screened and one observes a transition to QGP with magnetic confinement.

   hep-lathep-phhep-thnucl-thPoS(2022)·2 citations
2. 02*

   Bottomonium resonances from lattice QCD static-static-light-light potentials

   Lasse Mueller🇩🇪 · Pedro Bicudo🇵🇹 · Nuno Cardoso🇵🇹 · Marc Wagner🇩🇪

   We study $I=0$ quarkonium resonances decaying into pairs of heavy-light mesons using static-static-light-light potentials from lattice QCD. To this end, we solve a coupled channel Schrödinger equation with a confined quarkonium channel and channels with a heavy-light meson pair to compute phase shifts and $\text{mbox}T$ matrix poles for the lightest decay channel. We discuss our results for $S$, $P$, $D$ and $F$ wave states in the context of corresponding experimental results, in particular for ${\rm Y}(10753)$ and ${\rm Y}(10860)$.

   hep-lathep-phPoS(2022)·1 citation
3. 03*

   Synthetic complex Weyl superconductors, chiral Josephson effect and synthetic half-vortices

   Zahra Faraei🇮🇷 · S. A. Jafari🇮🇷

   We show that the most generic form of spin-singlet superconducting order parameter for chiral fermions is of the ${\Delta }_s+i{\gamma }^5{\Delta }_5$ where ${\Delta }_s$ is the usual order parameter and ${\Delta }_5$ is the pseudo-scalar order parameter. After factoring out the $U(1)$ phase $e^{i\varphi }$, this form of superconductivity admits yet additional complex structure in the plane of $({\Delta }_s,{\Delta }_5)$. The polar angle $\chi$ in this plane dubbed chiral angle will be locked to the $U(1)$ phase $\varphi$. We propose a synthetic setup based on stacking of topological insulators (TIs) and superconductors (SCs). Alternatively flux biasing the superconductors with a fluxes $\pm \Phi$ leads to ${\Delta }_5={\Delta }_0\sin (\chi )$, where ${\Delta }_0$ is the superconducting order parameter of the SC layers, and the chiral angle $\chi =\Phi /{\Phi }_0$ is directly given by the flux $\Phi$ in units of the flux quantum ${\Phi }_0=h/(2e)$. This can be used as a building block to construct a two-dimensional Josephson array. In this setup $\chi$ will be a background field defining a pseudoscalar ${\Delta }_5$ that can be tuned to desired configuration. While in a uniform background field ${\Delta }_5$ the dynamics of $\varphi$ is given by standard XY model and its associated vortices, a {\em staggered} background $\pm {\Delta }_5$ (or equivalently $\chi$ and $\chi +\pi$ in alternating lattice sites) creates a new set of minima for the $\varphi$ field that will support half-vortex excitations. An isolated single synthetic "half-vortex" in the $\chi$ field in an otherwise uniform background will bind a $\varphi$-half-vortex. This is similar to the way a p-wave superconducting vortex core binds a Majorana fermion.

   ↳ cond-mat.supr-concond-mat.stat-mechhep-lathep-thSci.Rep.(2023)·0 citations
4. 04*

   Tunning the tilt of a Dirac cone by atomic manipulations: application to 8Pmmn borophene

   Yasin Yekta🇮🇷 · Hanif Hadipour🇮🇷 · S. A. Jafari🇮🇷

   We decipher the microscopic mechanism of the formation of tilt in the two-dimensional Dirac cone of $8Pmmn$ borphene. In our ab-initio calculations, we identify relevant low-energy degrees of freedom on the $8Pmmn$ lattice and find that these atomic orbitals reside on an effective honeycomb lattice (inner sites), while the high-energy degrees of freedom reside on the rest of the $8Pmmn$ lattice (ridge sites). Integrating out the high-energy atomic orbitals, gives rise to remarkably large effective further neighbor hoppings on the coarse grained "honeycomb graph" of inner sites that determine the location and tilt of the Dirac cone. Molecular orbitals -- that can be modified by atomic manipulations -- are responsible for the creation of further neighbor edges on the honeycomb graph that controls the tilt of the resulting Dirac cone. This leads to an effective tight-binding model on a parent honeycomb graph that facilitates numerical modeling of various effects such as disorder/interactions/symmetry-breaking for tilted Dirac cone fermions. Since the tilt is a proxy to spacetime metric, our result offers a robust perspective on the fabrication of desired emergent spacetime structure and synthesis of geometric forces at ambient conditions that are likely to enhance our control on the movement of electrons in electric/optical devices.

   ↳ cond-mat.mtrl-scicond-mat.str-elgr-qchep-lat15 citations
5. 05*

   Simulating gauge theories with variational quantum eigensolvers in superconducting microwave cavities

   Jinglei Zhang🇨🇦 · Ryan Ferguson🇨🇦 · Stefan Kühn🇨🇾 · Jan F. Haase🇨🇦 · C.M. Wilson🇨🇦 · Karl Jansen🇩🇪 · Christine A. Muschik🇨🇦

   Quantum-enhanced computing methods are promising candidates to solve currently intractable problems. We consider here a variational quantum eigensolver (VQE), that delegates costly state preparations and measurements to quantum hardware, while classical optimization techniques guide the quantum hardware to create a desired target state. In this work, we propose a bosonic VQE using superconducting microwave cavities, overcoming the typical restriction of a small Hilbert space when the VQE is qubit based. The considered platform allows for strong nonlinearities between photon modes, which are highly customisable and can be tuned in situ, i.e. during running experiments. Our proposal hence allows for the realization of a wide range of bosonic ansatz states, and is therefore especially useful when simulating models involving degrees of freedom that cannot be simply mapped to qubits, such as gauge theories, that include components which require infinite-dimensional Hilbert spaces. We thus propose to experimentally apply this bosonic VQE to the U(1) Higgs model including a topological term, which in general introduces a sign problem in the model, making it intractable with conventional Monte Carlo methods.

   ↳ quant-phhep-latQuantum(2023)·33 citations
6. 06*

   Toward emulating nuclear reactions using eigenvector continuation

   C. Drischler🇺🇸 · M. Quinonez🇺🇸 · P. G. Giuliani🇺🇸 · A. E. Lovell🇺🇸 · F. M. Nunes🇺🇸

   We construct an efficient emulator for two-body scattering observables using the general (complex) Kohn variational principle and trial wave functions derived from eigenvector continuation. The emulator simultaneously evaluates an array of Kohn variational principles associated with different boundary conditions, which allows for the detection and removal of spurious singularities known as Kohn anomalies. When applied to the $K$-matrix only, our emulator resembles the one constructed by Furnstahl et al. [Phys. Lett. B 809, 135719] although with reduced numerical noise. After a few applications to real potentials, we emulate differential cross sections for ${}^{40}$Ca$(n,n)$ scattering based on a realistic optical potential and quantify the model uncertainties using Bayesian methods. These calculations serve as a proof of principle for future studies aimed at improving optical models.

   ↳ nucl-thhep-lathep-phnucl-exPLB(2021)·69 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.