Nuclear Theory·nucl-th

Thursday·June 18, 2020

11 papers—5 primary·6 cross-listed

06
Hydrodynamic attractor of a hybrid viscous fluid in Bjorken flow
Toshali Mitra🇮🇳 · Sukrut Mondkar🇮🇳 · Ayan Mukhopadhyay🇮🇳 · Anton Rebhan🇦🇹 · Alexander Soloviev🇺🇸
The nonequilibrium evolution in a boost-invariant Bjorken flow of a hybrid viscous fluid model containing two interacting components with different viscosities, such that they represent strongly and weakly self-coupled sectors, is shown to be characterized by a hydrodynamic attractor which has an early-time behavior that is reminiscent of the so-called bottom-up thermalization scenario in heavy-ion collisions. The hydrodynamization times for the two sectors can differ strongly, with details depending on the curve realized on the two-dimensional attractor surface, which might account for different scenarios for small and large systems in nuclear collisions. The total system behaves like a single viscous fluid with a dynamically determined effective shear viscosity.
↳ hep-phhep-thnucl-thPRResearch(2020)·24 citations
07
Nonrelativistic model of tetraquarks and predictions for their masses from fits to charmed and bottom meson data
Per Lundhammar🇸🇪 · Tommy Ohlsson🇸🇪
We investigate a nonrelativistic model of tetraquarks, which are assumed to be compact and to consist of diquark-antidiquark pairs. We fit, for the first time, basically all currently known values for the measured masses of 45 mesons, including both charmed and bottom mesons, to the model and predict masses of tetraquarks as well as diquarks. In particular, we find masses of four axial-vector diquarks, i.e., $q c$ , $cc$ , $q b$ , and $bb$ , where $q = u, d$ , and 24 ground-state tetraquarks, including both heavy-light tetraquarks ( $q c q c$ and $q b q b$ ) and heavy tetraquarks ( $cc cc$ and $bb bb$ ). In general, our results for the masses of $q b q b$ , $cc cc$ , and $bb bb$ are largely comparable with other reported results, whereas our results for the masses of $q c q c$ are slightly larger than what has been found earlier. Finally, we identify some of the obtained predictions for masses of tetraquarks with masses of experimental tetraquark candidates, and especially, we find that $ψ (4660)$ , $Z_{b} (10610)$ , and $Z_{b} (10650)$ could be described by the model.
↳ hep-phhep-exnucl-exnucl-thPRD(2020)·71 citations
08
Fractional quantum Hall physics and higher-order momentum correlations in a few spinful fermionic contact-interacting ultracold atoms in rotating traps
Constantine Yannouleas · Uzi Landman
The fractional quantum Hall effect (FQHE) is theoretically investigated, with numerical and algebraic approaches, in assemblies of a few spinful ultracold neutral fermionic atoms, interacting via repulsive contact potentials and confined in a single rapidly rotating two-dimensional harmonic trap. Going beyond the commonly used second-order correlations in the real configuration space, the methodology in this paper will assist the analysis of experimental observations by providing benchmark results for $N$ -body spin-unresolved, as well as spin-resolved, momentum correlations measurable in time-of-flight experiments with individual particle detection. Our analysis shows that the few-body lowest-Landau-level (LLL) states with good magic angular momenta exhibit inherent ordered quantum structures in the $N$ -body correlations, similar to those associated with rotating Wigner molecules (WMs), familiar from the field of semiconductor quantum dots under high magnetic fields. The application of a small perturbing stirring potential induces, at the ensuing avoided crossings, formation of symmetry broken states exhibiting ordered polygonal-ring structures, explicitly manifest in the single-particle density profile of the trapped particles. Away from the crossings, an LLL state obtained from exact diagonalization of the microscopic Hamiltonian, found to be well-described by a (1,1,1) Halperin two-component variational wavefunction, represents also a spinful rotating WM. Analysis of the calculated LLL wavefunction enables a two-dimensional generalization of the Girardeau one-dimensional 'fermionization' scheme, originally invoked for mapping of bosonic-type wave functions to those of spinless fermions.
↳ cond-mat.quant-gasnucl-thquant-phPRA(2020)·4 citations
09
Quantum nucleation of up-down quark matter and astrophysical implications
Jing Ren🇨🇳 · Chen Zhang🇨🇦
Quark matter with only $u$ and $d$ quarks ( $u d$ QM) might be the ground state of baryonic matter at large baryon number $A > A_{min}$ . With $A_{min} ≳ 300$ , this has no direct conflict with the stability of ordinary nuclei. An intriguing test of this scenario is to look for quantum nucleation of $u d$ QM inside neutron stars due to their large baryon densities. In this paper, we study the transition rate of cold neutron stars to $u d$ quark stars ( $u d$ QSs) and the astrophysical implications, considering the relevant theoretical uncertainties and observational constraints. It turns out that a large portion of parameter space predicts an instantaneous transition, and so the observed neutron stars are mostly $u d$ QSs. We find this possibility still viable under the recent gravitational wave and pulsar observations, although there are debates on its compatibility with some observations that involve complicated structure of quark matter. The tension could be partially relieved in the two-families scenario, where the high-mass stars ( $M ≳ 2 M_{⊙}$ ) are all $u d$ QSs and the low-mass ones ( $M \sim 1.4 M_{⊙}$ ) are mostly hadronic stars. In this case, the slow transition of the low-mass hadronic stars points to a very specific class of hadronic models with moderately stiff EOSs, and $u d$ QM properties are also strongly constrained.
↳ hep-phastro-ph.HEgr-qcnucl-thPRD(2020)·34 citations
10
Substantially enhanced deuteron-triton fusion probabilities in intense low-frequency laser fields
Xu Wang🇨🇳
Deuteron-triton (DT) fusion is the primary fusion reaction used in controlled fusion research, mainly for its relatively high reaction cross sections compared to other fusion options. Even so, to attain appreciable reaction probabilities very high temperatures (on the order of 10-100 million kelvins) are required, which are extremely challenging to achieve and maintain. We show that intense low-frequency laser fields, such as those in the near-infrared regime for the majority of intense laser facilities around the world, are highly effective in transferring energy to the DT system and enhancing the DT fusion probabilities. The fusion probabilities are shown to be enhanced by at least an order of magnitude in 800-nm laser fields with intensities on the order of 10 $^{21}$ W/cm $^{2}$ . The demanding temperature requirement of controlled nuclear fusion may be relaxed if intense low-frequency lasers are exploited.
↳ physics.atom-phnucl-thPRC(2020)·24 citations
11
From few to many bosons inside the unitary window: a transition between universal to non-universal behavior
A. Kievsky🇮🇹 · A. Polls🇪🇸 · B. Juliá-Díaz🇪🇸 · N. K. Timofeyuk🇬🇧 · M. Gattobigio🇫🇷
Universal behaviour in few-bosons systems close to the unitary limit, where two bosons become unbound, has been intensively investigated in recent years both experimentally and theoretically. In this particular region, called the unitary window, details of the inter-particle interactions are not important and observables, such as binding energies, can be characterized by a few parameters. With an increasing number of particles the short-range repulsion, present in all atomic, molecular or nuclear interactions, gradually induces deviations from the universal behaviour. In the present letter we discuss for the first time a simple way of incorporating non-universal behaviour through one specific parameter which controls the smooth transition of the system from universal to non-universal regime. Using a system of $N$ helium atoms as an example we calculate their ground state energies as trajectories within the unitary window and also show that the control parameters can be used to determine the energy per particle in homogeneous systems when $N \to \infty$ .
↳ cond-mat.quant-gasnucl-thPRA(2020)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE

Hydrodynamic attractor of a hybrid viscous fluid in Bjorken flow

Nonrelativistic model of tetraquarks and predictions for their masses from fits to charmed and bottom meson data

Fractional quantum Hall physics and higher-order momentum correlations in a few spinful fermionic contact-interacting ultracold atoms in rotating traps

Quantum nucleation of up-down quark matter and astrophysical implications

Substantially enhanced deuteron-triton fusion probabilities in intense low-frequency laser fields

From few to many bosons inside the unitary window: a transition between universal to non-universal behavior

Affiliations