Nuclear Theory·nucl-th

Friday·January 29, 2016

10 papers—5 primary·5 cross-listed

01
Effects of the tensor couplings on the nucleonic direct URCA processes in neutron star matter
Xu Yan · Huang Xiu-Lin · Liu Cheng-Zhi · Liu Guang-Zhou
The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter are investigated within the relativistic Hartree-Fock approximation. We study particularly the influences of the tensor couplings of vector mesons $ω$ and $ρ$ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons $ω$ and $ρ$ can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons $ω$ and $ρ$ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non-superfluid neutron star matter. However, when considering only the tensor coupling of vector meson $ρ$ , the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities.That is to say that the tensor coupling of vector meson $ρ$ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.
nucl-thastro-ph.HE0 citations
02
Probing neutron-proton dynamics by pions
Natsumi Ikeno · Akira Ono · Yasushi Nara · Akira Ohnishi
In order to investigate the nuclear symmetry energy at high density, we study the pion production in central collisions of neutron-rich nuclei $^{132} Sn +^{124} Sn$ at 300 MeV/nucleon using a new approach by combining the antisymmetrized molecular dynamics (AMD) and a hadronic cascade model (JAM). The dynamics of neutrons and protons is solved by AMD, and then pions and $Δ$ resonances in the reaction process are handled by JAM. We see the mechanism how the $Δ$ resonance and pions are produced reflecting the dynamics of neutrons and protons. We also investigate the impacts of cluster correlations as well as of the high-density symmetry energy on the nucleon dynamics and consequently on the pion ratio. We find that the $Δ^{-} / Δ^{++}$ production ratio agrees very well with the neutron-proton squared ratio $(N / Z)^{2}$ in the high-density and high-momentum region. We show quantitatively that $Δ$ production ratio, and therefore $(N / Z)^{2}$ , are directly reflected in the $π^{-} / π^{+}$ ratio, with modification in the final stage of the reaction.
nucl-thnucl-exPRC(2016)·69 citations
03
Odd tensor E3 transitions and the generalized seniority in Sn-isotopes
Bhoomika Maheshwari · Ashok Kumar Jain
In our recent paper [Phys. Lett. B 753, (2016) 122], we have shown that both the odd and even tensor electric transition probabilities exhibit similar behavior within the generalized seniority scheme in a multi-j environment. This microscopic approach was used to show for the first time the occurrence of seniority isomers in the $13^{-}$ isomers of Sn-isotopes, which decay by odd tensor $E 1$ transition to the same seniority ( $Δ v = 0$ ) state. In this letter, we extend our studies to odd tensor $E 3$ transitions connecting different seniority states ( $Δ v = 2$ ), and show for the first time that the generalized seniority scheme explains reasonably well the systematics of the $B (E 3)$ values for the $(0^{+} \to 3_{1}^{-})$ transitions in the Sn-isotopes. Additionally, we support these results by seniority guided Large Scale Shell Model (LSSM) calculations. The generalized seniority results are able to single out the most crucial valence space required in the LSSM calculations.
nucl-th1 citation
04
Asymmetric behavior of the B $(E 2 ↑; 0^{+} \to 2^{+})$ values in $^{104 - 130}$ Sn and Generalized Seniority
Bhoomika Maheshwari · Ashok Kumar Jain · Balraj Singh
We present freshly evaluated B $(E 2 ↑; 0^{+} \to 2^{+})$ values across the even-even Sn-isotopes which confirm the presence of an asymmetric behavior as well as a dip in the middle of the full valence space. We explain these features by using the concept of generalized seniority. The dip in the B $(E 2)$ values near $^{116}$ Sn is understood in terms of a change in the dominant orbits before and after the mid shell, which also explains the presence of asymmetric peaks in the B $(E 2)$ values. This approach helps in deciding the most active valence spaces for a given set of isotopes, and single out the most useful truncation scheme for Large Scale Shell Model (LSSM) calculations. The LSSM calculations so guided by generalized seniority are also able to reproduce the experimental data on B $(E 2) ↑$ values quite well.
nucl-thNPA(2016)·32 citations
05
Mass tomography at different momentum ranges in quark-gluon plasma
Magdalena Djordjevic🇷🇸 · Bojana Blagojevic🇷🇸 · Lidija Zivkovic🇷🇸
We here show that at lower momentum (i.e., $p_{⊥} \sim 10$ GeV) single particle suppression for different types of probes exhibit a clear mass hierarchy, which is a direct consequence of the differences in the energy loss, rather than the differences in the initial distributions. On the other hand, we predict that the mass hierarchy is not expected at high momentum (i.e., $p_{⊥} \sim 100$ GeV); i.e., while we surprisingly predict that suppression for charged hadrons will be somewhat smaller than the suppression for heavy mesons, we find that this difference will be a consequence of fragmentation functions, not the finite mass effects. That is, apart from the fragmentation functions, the probes of different masses exhibit nearly the same suppression in the high momentum region. We also argue that the same insensitivity on the probe types also appears for jets. In particular, the experimental data in the momentum regions where they exist for both types of probes, show similar suppressions of charged hadrons and inclusive jet data. Interestingly, we also find that our state-of-the-art suppression predictions for high momentum single particles are also in agreement with the jet suppression data, where the reasons behind this agreement yet remain to be understood. Finally, the available jet data also show (though with large error bars) an overlap between b jets (heavy) and inclusive jets (light) probes. Consequently, our results suggest that single particles in the momentum region below 50 GeV present an excellent tool for mass tomography, while high momentum single particles and (possibly) jets are somewhat insensitive to the details of the interaction with quark-gluon plasma.
nucl-thPRC(2016)·37 citations

Affiliations

first authorsco-authorsvia INSPIRE

Effects of the tensor couplings on the nucleonic direct URCA processes in neutron star matter

Probing neutron-proton dynamics by pions

Odd tensor E3 transitions and the generalized seniority in Sn-isotopes

Asymmetric behavior of the B(E2↑;0+→2+) values in 104−130Sn and Generalized Seniority

Mass tomography at different momentum ranges in quark-gluon plasma

Affiliations

Asymmetric behavior of the B $(E 2 ↑; 0^{+} \to 2^{+})$ values in $^{104 - 130}$ Sn and Generalized Seniority