Nuclear Theory·nucl-th

Wednesday·March 13, 2019

13 papers—7 primary·6 cross-listed

08
The Dynamical Diquark Model: First Numerical Results
Jesse F. Giron🇺🇸 · Richard F. Lebed🇺🇸 · Curtis T. Peterson🇺🇸
We produce the first numerical predictions of the dynamical diquark model of multiquark exotic hadrons. Using Born-Oppenheimer potentials calculated numerically on the lattice, we solve coupled and uncoupled systems of Schroedinger equations to obtain mass eigenvalues for multiplets of states that are, at this stage, degenerate in spin and isospin. Assuming reasonable values for these fine-structure splittings, we obtain a series of bands of exotic states with a common parity eigenvalue that agree well with the experimentally observed charmoniumlike states, and we predict a number of other unobserved states. In particular, the most suitable fit to known pentaquark states predicts states below the charmonium-plus-nucleon threshold. Finally, we examine the strictest form of Born-Oppenheimer decay selection rules for exotics and, finding them to fail badly, we propose a resolution by relaxing the constraint that exotics must occur as heavy-quark spin-symmetry eigenstates.
↳ hep-phnucl-thJHEP(2019)·67 citations
09
Probe Chiral Magnetic Effect with Signed Balance Function
A.H. Tang🇺🇸
In this paper a pair of observables are proposed as alternative ways, by examining the fluctuation of net momentum-ordering of charged pairs, to study the charge separation induced by the Chiral Magnetic Effect (CME) in relativistic heavy ion collisions. They are, the out-of-plane to in-plane ratio of fluctuation of the difference between signed balance functions measured in pair's rest frame, and the ratio of it to similar measurement made in the laboratory frame. Both observables have been studied with simulations including flow-related backgrounds, and for the first time, backgrounds that are related to resonance's global spin alignment. The two observables have similar positive responses to signal, and opposite, limited responses to identifiable backgrounds arising from resonance flow and spin alignment. Both observables have also been tested with two realistic models, namely, a multi-phase transport (AMPT) model and the anomalous-viscous fluid dynamics (AVFD) model. These two observables, when cross examined, will provide useful insights in the study of CME-induced charge separation.
↳ nucl-exnucl-thCPC(2020)·51 citations
10
Chiral phase transition temperature in (2+1)-Flavor QCD
H.-T. Ding🇨🇳 · P. Hegde🇮🇳 · O. Kaczmarek🇨🇳 · F. Karsch🇩🇪 · Anirban Lahiri🇩🇪 · S.-T. Li🇨🇳 · Swagato Mukherjee🇺🇸 · H. Ohno🇯🇵 · P. Petreczky🇺🇸 · C. Schmidt🇩🇪 · P. Steinbrecher🇺🇸
We present a lattice QCD based determination of the chiral phase transition temperature in QCD with two degenerate, massless quarks and a physical strange quark mass. We propose and calculate two novel estimators for the chiral transition temperature for several values of the light quark masses, corresponding to Goldstone pion masses in the range of $58 MeV ≲ m_{π} ≲ 163 MeV$ . The chiral phase transition temperature is determined by extrapolating to vanishing pion mass using universal scaling analysis. Finite volume effects are controlled by extrapolating to the thermodynamic limit using spatial lattice extents in the range of $2.8$ - $4.5$ times the inverse of the pion mass. Continuum extrapolations are carried out by using three different values of the lattice cut-off, corresponding to lattices with temporal extent $N_{τ} = 6, 8$ and $12$ . After thermodynamic, continuum and chiral extrapolations we find the chiral phase transition temperature $T_{c}^{0} = 13 2_{- 6}^{+ 3}$ MeV.
↳ hep-lathep-phhep-thnucl-thPRL(2019)·306 citations
11
Gauge ambiguity of the quark spectrum in the Color Glass Condensate
Francois Gelis🇫🇷 · Naoto Tanji🇮🇹
In the Color Glass Condensate, the inclusive spectrum of produced quarks in a heavy ion collision is obtained as the Fourier transform of a $2$ -fermion correlation function. Due to its non-locality, the two points of this function must be linked by a Wilson line in order to have a gauge invariant result, but when the quark spectrum is evaluated in a background that has a non-zero chromo-magnetic field, this procedure suffers from an ambiguity related to the choice of the contour defining the Wilson line. In this paper, we use an analytically tractable toy model of the background field in order to study this contour dependence. We show that for a straight contour, unphysical contributions to the spectrum in $p_{⊥}^{- 2}$ and $p_{⊥}^{- 3}$ cancel, leading to a spectrum with a tail in $p_{⊥}^{- 4}$ . If the contour defining the Wilson line deviates from a straight line, the path dependence is at most of order $p_{⊥}^{- 5}$ if its curvature is bounded, and of order $p_{⊥}^{- 4}$ otherwise. When the contour is forced to go through a fixed point, the path dependence is even larger, of order $p_{⊥}^{- 2}$ .
↳ hep-phnucl-thNPA(2019)·2 citations
12
Unified equations of state for cold non-accreting neutron stars with Brussels-Montreal functionals. I. Role of symmetry energy
J. M. Pearson🇨🇦 · N. Chamel🇧🇪 · A. Y. Potekhin🇷🇺 · A. F. Fantina🇧🇪 · C. Ducoin🇫🇷 · A. K. Dutta🇨🇦 · S. Goriely🇧🇪
The theory of the nuclear energy-density functional is used to provide a unified and thermodynamically consistent treatment of all regions of cold non-accreting neutron stars. In order to assess the impact of our lack of complete knowledge of the density dependence of the symmetry energy on the constitution and the global structure of neutron stars, we employ four different functionals. All of them were precision fitted to essentially all the nuclear-mass data with the Hartree-Fock-Bogoliubov method and two different neutron-matter equations of state based on realistic nuclear forces. For each functional, we calculate the composition, the pressure-density relation, and the chemical potentials throughout the star. We show that uncertainties in the symmetry energy can significantly affect the theoretical results for the composition and global structure of neutron stars. To facilitate astrophysical applications, we construct analytic fits to our numerical results.
↳ astro-ph.HEnucl-thMNRAS(2018)·270 citations
13
The $ss s ˉ s ˉ$ tetraquark states and the newly observed structure $X (2239)$ by BESIII Collaboration
Qi-Fang Lü🇨🇳 · Kai-Lei Wang🇨🇳 · Yu-Bing Dong🇨🇳
We investigate the mass spectrum of the $ss s ˉ s ˉ$ tetraquark states within the relativized quark model. By solving the Schrödinger-like equation with the relativized potential, the masses of the $S -$ and $P -$ wave $ss s ˉ s ˉ$ tetraquarks are obtained. The screening effects are also taken into account. It is found that the observed resonant structure $X (2239)$ in the $e^{+} e^{-} \to K^{+} K^{-}$ process by BESIII Collaboration can be assigned as a $P -$ wave $1^{--}$ $ss s ˉ s ˉ$ tetraquark state. Furthermore, the radiative transition and strong decay behaviors of this structure are also estimated, which can provide helpful information for future experimental searches.
↳ hep-phhep-exnucl-thCPC(2020)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

The Dynamical Diquark Model: First Numerical Results

Probe Chiral Magnetic Effect with Signed Balance Function

Chiral phase transition temperature in (2+1)-Flavor QCD

Gauge ambiguity of the quark spectrum in the Color Glass Condensate

Unified equations of state for cold non-accreting neutron stars with Brussels-Montreal functionals. I. Role of symmetry energy

The sssˉsˉ tetraquark states and the newly observed structure X(2239) by BESIII Collaboration

Affiliations

The $ss s ˉ s ˉ$ tetraquark states and the newly observed structure $X (2239)$ by BESIII Collaboration