Nuclear Theory·nucl-th

Wednesday·September 12, 2018

12 papers—6 primary·6 cross-listed

07
[Submitted on 8 Sept 2018] (cross-list from hep-ph)
Effect of an absorbing medium on particle oscillations
Valeriy Nazaruk🇷🇺
Particle oscillations in absorbing matter are considered. The approach based on the optical potential is shown to be inapplicable in the strong absorption region. Models with Hermitian Hamiltonian are analyzed. They give an increase of the process width in comparison with the model based on the optical potential.
Comments:
9 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.02841 [pdf]
PRC(2019)·1 citation
08
[Submitted on 10 Sept 2018] (cross-list from hep-ph)
Weak Neutral Current Axial Form Factor Using $(ν ˉ) ν$ -Nucleon Scattering and Lattice QCD Inputs
Raza Sabbir Sufian🇺🇸 · Keh-Fei Liu🇺🇸 · David G. Richards🇺🇸
We present a determination of the neutral current weak axial charge $G_{A}^{Z} (0) = - 0.654 (3)_{stat} (5)_{sys}$ using the strange quark axial charge $G_{A}^{s} (0)$ calculated with lattice QCD. We then perform a phenomenological analysis, where we combine the strange quark electromagnetic form factor from lattice QCD with (anti)neutrino-nucleon scattering differential cross section from MiniBooNE experiments in a momentum transfer region $0.24 ≲ Q^{2} ≲ 0.71$ GeV $^{2}$ to determine the neutral current weak axial form factor $G_{A}^{Z} (Q^{2})$ in the range of $0 ≲ Q^{2} \leq 1$ GeV $^{2}$ . This yields a phenomenological value of $G_{A}^{Z} (0) = - 0.687 (89)_{stat} (40)_{sys}$ . The value of $G_{A}^{Z} (0)$ constrained by the lattice QCD calculation of $G_{A}^{s} (0)$ , when compared to its phenomenological determination, provides a significant improvement in precision and accuracy and can be used to provide a constraint on the fit to $G_{A}^{Z} (Q^{2})$ for $Q^{2} > 0$ . This constrained fit leads to an unambiguous determination of (anti)neutrino-nucleon neutral current elastic scattering differential cross section near $Q^{2} = 0$ and can play an important role in numerically isolating nuclear effects in this region. We show a consistent description of $G_{A}^{Z} (Q^{2})$ obtained from the (anti)neutrino-nucleon scattering cross section data requires a nonzero contribution of the strange quark electromagnetic form factor. We demonstrate the robustness of our analysis by providing a post-diction of the BNL E734 experimental data.
Comments:
Published Version (20 pages, 4 figures)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.03509 [pdf]
JHEP(2020)·17 citations
09
[Submitted on 10 Sept 2018] (cross-list from hep-ph)
$J / ψ$ polarization in the CGC+NRQCD approach
Yan-Qing Ma🇨🇳 · Tomasz Stebel🇵🇱 · Raju Venugopalan🇺🇸
We compute the $J / ψ$ polarization observables $λ_{θ}$ , $λ_{ϕ}$ , $λ_{θ ϕ}$ in a Color Glass Condensate (CGC) + nonrelativistic QCQ (NRQCD) formalism that includes contributions from both color singlet and color octet intermediate states. Our results are compared to low $p_{T}$ data on $J / ψ$ polarization from the LHCb and ALICE experiments on proton-proton collisions at center-of-mass energies of $s = 7$ TeV and 8 TeV. Our CGC+NRQCD computation provides a better description of data for $p_{T} \leq 15$ GeV relative to extant next-to-leading (NLO) calculations within the collinear factorization framework. These results suggest that higher order computations in the CGC+NRQCD framework have the potential to greatly improve the accuracy of extracted values of the NRQCD universal long distance matrix elements.
Comments:
26 pages, 8 figures, accepted for publication in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.03573 [pdf]
JHEP(2018)·47 citations
10
[Submitted on 11 Sept 2018] (cross-list from hep-ph)
Effect of Hagedorn States on Isothermal Compressibility of Hadronic Matter formed in Heavy-Ion Collisions: From NICA to LHC Energies
Arvind Khuntia🇮🇳 · Swatantra Kumar Tiwari🇮🇳 · Pramod Sharma🇮🇳 · Raghunath Sahoo🇮🇳 · Tapan Kumar Nayak🇮🇳
In this work, we have studied the isothermal compressibility ( $κ_{T}$ ) as a function of temperature, baryon chemical potential and centre-of-mass energy ( $s_{N N}$ ) using hadron resonance gas (HRG) and excluded-volume hadron resonance gas (EV-HRG) models. A mass cut-off dependence of isothermal compressibility has been studied for a physical resonance gas. Further, we study the effect of heavier resonances ( $>$ 2 GeV) on the isothermal compressibility by considering the Hagedorn mass spectrum, $ρ (m) \sim exp (bm) / (m^{2} + m_{0}^{2})^{5/4}$ . Here, the parameters, $b$ and $m_{0}$ are extracted after comparing the results of recent lattice QCD simulations at finite baryonic chemical potential. We find a significant difference between the results obtained in EV-HRG and HRG models at a higher temperatures and higher baryochemical potentials. The inclusion of the Hagedorn mass spectrum in the partition function for hadron gas has a large effect at a higher temperature. A higher mass cut-off in the Hagedorn mass spectrum takes the isothermal compressibility to a minimum value, which occurs near the Hagedorn temperature ( $T_{H}$ ). We show explicitly that at the future low energy accelerator facilities like FAIR (CBM), Darmstadt and NICA, Dubna the created matter would be incompressible compared to the high energy facilities like RHIC and LHC.
Comments:
Same as published paper
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.03780 [pdf]
PRC(2019)·20 citations
11
[Submitted on 11 Sept 2018] (cross-list from hep-ph)
Energy dependent kinetic freeze-out temperature and transverse flow velocity in high energy collisions
Li-Li Li🇨🇳 · Fu-Hu Liu🇨🇳
Transverse momentum spectra of negative and positive pions produced at mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton collisions and in central nucleus-nucleus collisions over an energy range from a few GeV to above 10 TeV are analyzed by a (two-component) blast-wave model with Boltzmann-Gibbs statistics and with Tsallis statistics respectively. The model results are in similarly well agreement with the experimental data measured by a few productive collaborations who work at the Heavy Ion Synchrotron (SIS), Super Proton Synchrotron (SPS), Relativistic Heavy Ion Collider (RHIC), and Large Hadron Collider (LHC), respectively. The energy dependent kinetic freeze-out temperature and transverse flow velocity are obtained and analyzed. Both the quantities have quick increase from the SIS to SPS, and slight increase or approximate invariability from the top RHIC to LHC. Around the energy bridge from the SPS to RHIC, the considered quantities in proton-proton collisions obtained by the blast-wave model with Boltzmann-Gibbs statistics show more complex energy dependent behavior comparing with the results in other three cases.
Comments:
Updated version, 16 pages, 4 figures. Only the first component is used to extract $T_{0}$ and $β_{T}$ . Conclusions unchanged. arXiv admin note: text overlap with arXiv:1805.03342
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.03881 [pdf]
EPJA(2018)·27 citations
12
[Submitted on 11 Sept 2018] (cross-list from hep-ph)
Rho Meson spectral function in hot asymmetric nuclear matter
P.C. Raje Bhageerathi🇮🇳
The rho meson spectral function in hot and dense asymmetric nuclear matter (number densities of proton and neutron different) is evaluated in an effective chiral SU(3) model within the mean field approximation (MFA). The dependence of the vector meson masses on density and temperature, their variation with the asymmetry parameter, the form of the spectral function when the p <-> n symmetry is broken are studied. One can observe clear splitting of the longitudinal and the transverse modes among the rho isospin multiplets. The role of a running tensor coupling on the spectral function is also studied.
Comments:
25 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.04021 [pdf]
EPJA(2019)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Effect of an absorbing medium on particle oscillations

Weak Neutral Current Axial Form Factor Using (νˉ)ν-Nucleon Scattering and Lattice QCD Inputs

J/ψ polarization in the CGC+NRQCD approach

Effect of Hagedorn States on Isothermal Compressibility of Hadronic Matter formed in Heavy-Ion Collisions: From NICA to LHC Energies

Energy dependent kinetic freeze-out temperature and transverse flow velocity in high energy collisions

Rho Meson spectral function in hot asymmetric nuclear matter

Affiliations

Weak Neutral Current Axial Form Factor Using $(ν ˉ) ν$ -Nucleon Scattering and Lattice QCD Inputs

$J / ψ$ polarization in the CGC+NRQCD approach