Nuclear Theory·nucl-th

Wednesday·March 11, 2015

10 papers—5 primary·5 cross-listed

01
Electromagnetic deuteron form factors in point form relativistic quantum mechanics
N. A. Khokhlov
A study of electromagnetic structure of the deuteron in the framework of relativistic quantum mechanics is presented. The deuteron form factors dependencies on the transferred 4-momentum Q are calculated. We compare results obtained with different realistic deuteron wave functions stemming from Nijmegen-I, Nijmegen-II, JISP16, CD-Bonn, Paris and Moscow (with forbidden states) potentials. A nucleon form factor parametrization consistent with modern experimental analysis was used as an input data.
nucl-th1 citation
02
Hybrid neutron stars with the Dyson-Schwinger quark model and various quark-gluon vertices
H. Chen🇨🇳 · J.-B. Wei🇨🇳 · M. Baldo🇮🇹 · G. F. Burgio🇮🇹 · H.-J. Schulze🇮🇹
We study cold dense quark matter and hybrid neutron stars with a Dyson-Schwinger quark model and various choices of the quark-gluon vertex. We obtain the equation of state of quark matter in beta equilibrium and investigate the hadron-quark phase transition in combination with a hadronic equation of state derived within the Brueckner-Hartree-Fock many-body theory. Comparing with the results for quark matter with the rainbow approximation, the Ball-Chiu ansatz and the 1BC ansatz for the quark-gluon vertex lead to a reduction of the effective interaction at finite chemical potential, qualitatively similar to the effect of our gluon propagator. We find that the phase transition and the equation of state of the quark or mixed phase and consequently the resulting hybrid star mass and radius depend mainly on a global reduction of the effective interaction due to effects of both the quark-gluon vertex and gluon propagator, but are not sensitive to the vertex ansatz.
nucl-thastro-ph.SRPRD(2015)·40 citations
03
Antihyperon potentials in nuclei via exclusive antiproton-nucleus reactions at FAIR
Alicia Sanchez Lorente🇩🇪 · Sebastian Bleser🇩🇪 · Marcell Steinen🇩🇪 · Josef Pochodzalla🇩🇪
The exclusive production of hyperon-antihyperon pairs close to their production threshold in antiproton - nucleus collisions offers a unique and hitherto unexplored opportunity to elucidate the behaviour of antihyperons in nuclei. For the first time we analyse these reactions in a microscopic transport model using the the Gießen Boltzmann-Uehling-Uhlenbeck transport model. The calculation take the delicate interplay between the strong absorption of antihyperons, their rescattering and refraction at the nuclear surface as well as the Fermi motion of the struck nucleon into account. We find a substantial sensitivity of transverse momentum correlations of coincident $Λ Λ$ -pairs to the assumed depth of the $Λ$ -potential. Because of the high cross section for this process and the simplicity of the experimental method our results are highly relevant for future activities at the international Facility for Antiproton and Ion Research (FAIR).
nucl-thnucl-exPLB(2015)·7 citations
04
Effects of deformation on the beta-decay patterns of light even-even and odd-mass Hg and Pt isotopes
J. M. Boillos · P. Sarriguren
Bulk and decay properties, including deformation energy curves, charge mean square radii, Gamow-Teller (GT) strength distributions, and beta-decay half-lives, are studied in neutron-deficient even-even and odd-A Hg and Pt isotopes. The nuclear structure is described microscopically from deformed quasiparticle random-phase approximation calculations with residual interactions in both particle-hole and particle-particle channels, performed on top of a self-consistent deformed quasiparticle Skyrme Hartree-Fock basis. The observed sensitivity of the, not yet measured, GT strength distributions to deformation is proposed as an additional complementary signature of the nuclear shape. The $β$ -decay half-lives resulting from these distributions are compared to experiment to demonstrate the ability of the method.
nucl-thPRC(2015)·29 citations
05
Tomography of the Quark-Gluon-Plasma by Charm Quarks
Taesoo Song🇩🇪 · Hamza Berrehrah🇩🇪 · Daniel Cabrera🇩🇪 · Juan M. Torres-Rincon🇫🇷 · Laura Tolos🇩🇪 · Wolfgang Cassing🇩🇪 · Elena Bratkovskaya🇩🇪
We study charm production in ultra-relativistic heavy-ion collisions by using the Parton-Hadron-String Dynamics (PHSD) transport approach. The initial charm quarks are produced by the Pythia event generator tuned to fit the transverse momentum spectrum and rapidity distribution of charm quarks from Fixed-Order Next-to-Leading Logarithm (FONLL) calculations. The produced charm quarks scatter in the quark-gluon plasma (QGP) with the off-shell partons whose masses and widths are given by the Dynamical Quasi-Particle Model (DQPM) which reproduces the lattice QCD equation-of-state in thermal equilibrium. The relevant cross section are calculated in a consistent way by employing the effective propagators and couplings from the DQPM. Close to the critical energy density of the phase transition, the charm quarks are hadronized into $D$ mesons through coalescence and/or fragmentation depending on transverse momentum. The hadronized $D$ mesons then interact with the various hadrons in the hadronic phase with cross sections calculated in an effective lagrangian approach with heavy-quark spin symmetry. Finally, the nuclear modification factor $R_{AA}$ and the elliptic flow $v_{2}$ of $D^{0}$ mesons from PHSD are compared with the experimental data from the STAR Collaboration for Au+Au collisions at $s_{NN}$ =200 GeV. We find that in the PHSD the energy loss of $D$ mesons at high $p_{T}$ can be dominantly attributed to partonic scattering while the actual shape of $R_{AA}$ versus $p_{T}$ reflects the heavy quark hadronization scenario, i.e. coalescence versus fragmentation. Also the hadronic rescattering is important for the $R_{AA}$ at low $p_{T}$ and enhances the $D$ -meson elliptic flow $v_{2}$ .
nucl-thhep-phnucl-exPRC(2015)·233 citations
06
Massive hybrid stars with a first order phase transition
A. Li🇨🇳 · W. Zuo🇨🇳 · G.-X. Peng🇨🇳
We develop our previous study of the transition to deconfined quark phase in neutron stars, including the interaction in the quark equation of state to the leading order in the perturbative expansion within the confinement density-dependent mass model. Using the Gibbs conditions the hadron-quark mixed phase is constructed matching the latter with the hadron equation of state derived from the microscopic Brueckner-Hartree-Fock approximation. The influence of quark interaction parameters on threshold properties and phase diagram of dense neutron star matter are discussed in detail. We find that the leading-order quark interaction expands the density range of the mixed phase, pushing forward the disappearance of the hadron phase. Moreover, since the equation of state could turn out to be stiffer, a high-mass hybrid star is possible with mixed-phase core with typical parameter sets.
↳ astro-ph.SRnucl-thPRC(2015)·58 citations
07
Forward $J / ψ$ production in proton-nucleus collisions at high energy
B. Ducloué🇫🇮 · T. Lappi🇫🇮 · H. Mäntysaari🇫🇮
Inclusive production of $J / ψ$ mesons, especially at forward rapidities, is an important probe of small-x gluons in protons and nuclei. In this paper we re-evaluate the production cross sections in the Color Glass Condensate framework, where the process is described by a large x gluon from the probe splitting into a quark pair and eikonally interacting with the target proton or nucleus. Using a standard collinear gluon distribution for the probe and an up to date dipole cross section fitted to HERA data to describe the target we achieve a rather good description of the cross section in proton-proton collisions, although with a rather large normalization uncertainty. More importantly, we show that generalizing the dipole cross section to nuclei in the Glauber approach results in a nuclear suppression of $J / ψ$ production that is much closer to the experimental data than claimed in previous literature.
↳ hep-phnucl-thPRD(2015)·116 citations
08
Finite size of hadrons and Bose-Einstein correlations in $pp$ collisions at 7 TeV
Andrzej Bialas🇵🇱 · Wojciech Florkowski🇵🇱 · Kacper Zalewski🇵🇱
Space-time correlations between produced particles, induced by the composite nature of hadrons, imply specific changes in the properties of the correlation functions for identical particles. The expected magnitude of these effects is evaluated using the recently published blast-wave model analysis of the data for $pp$ collisions at $s$ = 7 TeV.
↳ hep-phnucl-thPLB(2015)·9 citations
09
Predictions for the $Λ_{b} \to J / ψ Λ (1405)$ decay
Luis Roca🇪🇸 · Maxim Mai🇩🇪 · Eulogio Oset🇪🇸 · Ulf-G. Meißner🇩🇪
We calculate the shape of the $π Σ$ and $K ˉ N$ invariant mass distributions in the $Λ_{b} \to J / ψ π Σ$ and $Λ_{b} \to J / ψ K ˉ N$ decays that are dominated by the $Λ (1405)$ resonance. The weak interaction part is the same for both processes and the hadronization into the different meson-baryon channels in the final state is related by SU(3) symmetry. The most important feature is the implementation of the meson-baryon final-state interaction using two chiral unitary models from different theoretical groups. Both approaches give a good description of antikaon-nucleon scattering data, the complex energy shift in kaonic hydrogen and the line shapes of $π Σ K$ in photoproduction, based on the two-pole scenario for the $Λ (1405)$ . We find that this reaction reflects more the higher mass pole and we make predictions of the line shapes and relative strength of the meson-baryon distributions in the final state.
↳ hep-phhep-exnucl-thEPJC(2015)·77 citations
10
Confining Dyon-Anti-Dyon Coulomb Liquid Model I
Yizhuang Liu🇺🇸 · Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸
We revisit the dyon-anti-dyon liquid model for the Yang-Mills confining vacuum discussed by Diakonov and Petrov, by retaining the effects of the classical interactions mediated by the streamline between the dyons and anti-dyons. In the SU(2) case the model describes a 4-component strongly interacting Coulomb liquid in the center symmetric phase. We show that in the linearized screening approximation the streamline interactions yield Debye-Huckel type corrections to the bulk parameters such as the pressure and densities, but do not alter significantly the large distance behavior of the correlation functions in leading order. The static scalar and charged structure factors are consistent with a plasma of a dyon-anti-dyon liquid with a Coulomb parameter $Γ_{D D ˉ} \approx 1$ in the dyon-anti-dyon channel. Heavy quarks are still linearly confined and the large spatial Wilson loops still exhibit area laws in leading order. The t $^{'}$ Hooft loop is shown to be 1 modulo Coulomb corrections.
↳ hep-phhep-thnucl-thPRD(2015)·69 citations

Affiliations

first authorsco-authorsvia INSPIRE