Nuclear Theory·nucl-th

Wednesday·September 30, 2015

15 papers—6 primary·9 cross-listed

07
Relativistic, model-independent, multichannel $2 \to 2$ transition amplitudes in a finite volume
Raúl A. Briceño🇺🇸 · Maxwell T. Hansen🇩🇪
We derive formalism for determining $2 + J \to 2$ infinite-volume transition amplitudes from finite-volume matrix elements. Specifically, we present a relativistic, model-independent relation between finite-volume matrix elements of external currents and the physically observable infinite-volume matrix elements involving two-particle asymptotic states. The result presented holds for states composed of two scalar bosons. These can be identical or non-identical and, in the latter case, can be either degenerate or non-degenerate. We further accommodate any number of strongly-coupled two-scalar channels. This formalism will, for example, allow future lattice QCD calculations of the $ρ$ -meson form factor, in which the unstable nature of the $ρ$ is rigorously accommodated.
↳ hep-latnucl-thPRD(2016)·124 citations
08
Nucleon Resonance Transition Formfactors
I. G. Aznauryan🇦🇲 · V. D. Burkert🇺🇸 · V. I. Mokeev🇺🇸
We discuss recent results from CLAS on electromagnetic resonance transition amplitudes and their dependence on the distance scale ( $Q^{2}$ ). From the comparison of these results with most advanced theoretical calculations within QCD-based approaches there is clear evidence that meson-baryon contributions are present and important at large distances, i.e. small $Q^{2}$ , and that quark core contributions dominate the short distance behavior.
↳ nucl-exhep-lathep-phnucl-th1 citation
09
Appearance of novel modes of $D ˉ$ mesons in the Dual Chiral Density Wave
Daiki Suenaga🇯🇵 · Masayasu Harada🇯🇵
We calculate dispersion relations for $D ˉ (0^{-})$ , $D ˉ^{*} (1^{-})$ , $D ˉ_{0}^{*} (0^{+})$ and $D ˉ_{1} (1^{+})$ mesons in the Dual Chiral Density Wave (DCDW) where the chiral symmetry is spontaneously broken by inhomogeneous chiral condensate. Employing the Bloch's theorem, we show that all the modes have opposite group velocity to the momentum in the low-momentum region and the energy is minimized at non-zero momentum. Furthermore, the magnitude of momentum which realizes the minimum energy is equal to the wave number of the density wave.
↳ hep-phnucl-thPRD(2016)·14 citations
10
On Extraction of Chemical Potentials of Quarks from Particle Transverse Momentum Spectra in High Energy Collisions
Hong Zhao🇨🇳 · Fu-Hu Liu🇨🇳
We present two methods to extract the chemical potentials of quarks in high energy collisions. The first method is based on the ratios of negatively/positively charged particles, and the temperatures extracted from the transverse momentum spectra of related hadrons are needed. The second method is based on the chemical potentials of some particles, and we also need the transverse momentum spectra of related hadrons. To extract the quark chemical potentials, we would like to propose experimental collaborations to measure simultaneously not only the transverse momentum spectra of anti-p, p, K^-, K^+, pion^-, and pion^+, but also those of D^-, D^+, B^-, and B^+ (even those of Delta^++, Delta^-, and Omega^-) in high energy nuclear collisions
↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2015)·9 citations
11
On pseudorapidity distribution and speed of sound in high energy heavy ion collisions based on a new revised Landau hydrodynamic model
Li-Na Gao🇨🇳 · Fu-Hu Liu🇨🇳
We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources namely the central, target, and projectile sources respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. In the calculation, to avoid the errors caused by an unapt conversion or non-division, the rapidity and pseudorapidity distributions are obtained respectively. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider (RHIC), large hadron collider (LHC), and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy ion collisions at RHIC and LHC energies, the central source undergoes through a phase transition from hadronic gas to quark-gluon plasma (QGP) liquid phase; meanwhile, the target/projectile sources remain in the state of hadronic gas. The present work confirms that the QGP is of liquid type rather than that of a gas. The whole region of participants undergoes through a mixed phase consisting of a large quantity of (>90%) QGP liquid and a small quantity of (<10%) hadronic gas.
↳ nucl-exhep-exhep-phnucl-thAdv.High Energy Phys.(2015)·18 citations
12
Evidence of sub-nucleonic degrees of freedom in J/ $ψ$ photoproduction in ultraperipheral collisions at the CERN Large Hadron Collider
E. Andrade-II🇧🇷 · I. González🇧🇷 · A. Deppman🇧🇷 · C. A. Bertulani🇺🇸
We present calculations for the incoherent photoproduction of J/ $ψ$ vector mesons in ultra-peripheral heavy ion collisions (UPC) in terms of hadronic interactions. This study was carried out using the recently developed Monte Carlo model CRISP extended to include UPCs at LHC energies. A careful study of re-scattering and destruction of the J/ $ψ$ particles is presented for PbPb collisions at $s_{N N} = 2.76$ TeV. We have also compared our method to AuAu collisions at $s_{N N} = 200$ GeV measured at RHIC.
↳ hep-phnucl-thPRC(2015)·9 citations
13
Debye screening mass of hot Yang-Mills theory to three-loop order
Ioan Ghisoiu🇫🇮 · Jan Moller🇩🇪 · York Schroder🇨🇱
Building upon our earlier work, we compute a Debye mass of finite-temperature Yang-Mills theory to three-loop order. As an application, we determine a $g^{7}$ contribution to the thermodynamic pressure of hot QCD.
↳ hep-phhep-latnucl-thJHEP(2015)·39 citations
14
Hydrodynamic Waves in an Anomalous Charged Fluid
Navid Abbasi🇮🇷 · Ali Davody🇮🇷 · Kasra Hejazi🇮🇷 · Zahra Rezaei🇮🇷
We study the collective excitations in a relativistic fluid with an anomalous $U (1)$ current. In $3 + 1$ dimensions at zero chemical potential, in addition to ordinary sound modes we find two propagating modes in presence of an external magnetic field. The first one which is a transverse degenerate mode, propagates with a velocity proportional to the coefficient of gravitational anomaly; this is in fact the Chiral Alfvén wave recently found in \cite{Yamamoto:2015ria}. Another one is a wave of density perturbation, namely a chiral magnetic wave (CMW). The velocity dependence of CMW on the chiral anomaly coefficient is well known. We compute the dependence of CMW's velocity on the coefficient of gravitational anomaly as well. We also show that the dissipation splits the degeneracy of CAW. At finite chiral charge density we show that in general there may exist five chiral hydrodynamic waves. Of these five waves, one is the CMW while the other four are mixed Modified Sound-Alfvén waves. It turns out that in propagation transverse to the magnetic field no anomaly effect appear while in parallel to the magnetic field we find sound waves become dispersive due to anomaly.
↳ hep-thhep-phnucl-thPLB(2016)·18 citations
15
Charm Degrees of Freedom in Quark Gluon Plasma
Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Sayantan Sharma🇺🇸
Lattice QCD studies on fluctuations and correlations of charm quantum number have established that deconfinement of charm degrees of freedom sets in around the chiral crossover temperature, $T_{c}$ , i.e. charm degrees of freedom carrying fractional baryonic charge start to appear. By reexamining those same lattice QCD data we show that, in addition to the contributions from quark-like excitations, the partial pressure of charm degrees of freedom may still contain significant contributions from open-charm meson and baryon-like excitations associated with integral baryonic charges for temperatures up to $1.2 T_{c}$ . Charm quark-quasiparticles become the dominant degrees of freedom for temperatures $T > 1.2 T_{c}$ .
↳ hep-lathep-phnucl-thPRD(2016)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE