Nuclear Theory·nucl-th

Friday·July 17, 2015

12 papers—6 primary·6 cross-listed

07
[Submitted on 14 Jul 2015] (cross-list from hep-ph)
Identifying exotic hidden-charm pentaquarks
Rui Chen🇨🇳 · Xiang Liu🇨🇳 · Xue-Qian Li🇨🇳 · Shi-Lin Zhu🇨🇳
The LHCb Collaboration at the Large Hadron Collider at CERN discovered two pentaquark states $P_{c} (4380)$ and $P_{c} (4450)$ . These two hidden-charm states are interpreted as the loosely bound $Σ_{c} (2455) D^{*}$ and $Σ_{c}^{*} (2520) D^{*}$ molecular states in the boson exchange interaction model, which provides an explanation for why the experimental width of $P_{c} (4450)$ is much narrower than that of $P_{c} (4380)$ . The discovery of the new resonances $P_{c} (4380)$ and $P_{c} (4450)$ , indeed, opens a new page for hadron physics. The partners of $P_{c} (4380)$ and $P_{c} (4450)$ should be pursued in future experiments.
Comments:
5 pages, 2 tables and 1 figure. More discussions and references added. Accepted by Phys. Rev. Lett
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1507.03704 [pdf]
PRL(2015)·341 citations
08
[Submitted on 16 Jul 2015] (cross-list from nucl-ex)
Direct mass measurements of Cd isotopes show strong shell gap at N=82
R. Knöbel🇩🇪 · M. Diwisch🇩🇪 · F. Bosch🇩🇪 · D. Boutin🇩🇪 · L. Chen🇩🇪 · C. Dimopoulou🇩🇪 · A. Dolinskii🇩🇪 · B. Franczak🇩🇪 · B. Franzke🇩🇪 · H. Geissel🇩🇪 · M. Hausmann🇺🇸 · C. Kozhuharov🇩🇪 and 23 other authors
A $^{238}$ U projectile beam was used to create cadmium isotopes via abrasion-fission at 410 MeV/u in a beryllium target at the entrance of the in-flight separator FRS at GSI. The fission fragments were separated with the FRS and injected into the isochronous storage ring ESR for mass measurements. The Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B $ρ$ -tagging at the dispersive central focal plane of the FRS. In the experiment with B $ρ$ -tagging the magnetic rigidity of the injected fragments was determined by an accuracy of $2 \times 1 0^{- 4}$ . A new method of data analysis, using a correlation matrix for the combined data set from both experiments, has provided mass values for 25 different isotopes for the first time. The high selectivity and sensitivity of the experiment and analysis has given access even to rare isotopes detected with a few atoms per week. In this letter we present for the $^{129, 130, 131}$ Cd isotopes mass values directly measured for the first time. The Cd results clearly show a very pronounced shell effect at $N = 82$ which is in agreement with the conclusion from $γ$ -ray spectroscopy of $^{130}$ Cd and confirms the assumptions of modern shell-model calculations.
Comments:
7 pages, 5 figures, 3 tables
Subjects:
Nuclear Experiment (nucl-ex); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1507.04470 [pdf]
0 citations
09
[Submitted on 16 Jul 2015] (cross-list from astro-ph.HE)
Rotation-induced deep crustal heating of millisecond pulsars
M.E. Gusakov · E.M. Kantor · A. Reisenegger
The spin-down of a neutron star, e.g. due to magneto-dipole losses, results in compression of the stellar matter and induces nuclear reactions at phase transitions between different nuclear species in the crust. We show that this mechanism is effective in heating recycled pulsars, in which the previous accretion process has already been compressing the crust, so it is not in nuclear equilibrium. We calculate the corresponding emissivity and confront it with available observations, showing that it might account for the likely thermal ultraviolet emission of PSR J0437-4715.
Comments:
5 pages, 3 figures, accepted for publication in MNRAS Letters
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1507.04586 [pdf]
MNRAS(2015)·28 citations
10
[Submitted on 16 Jul 2015] (cross-list from astro-ph.HE)
Proton gaps and cooling of neutron stars with a stiff hadronic EoS
Hovik Grigorian🇷🇺 · Dmitry N. Voskresensky🇷🇺 · David Blaschke🇷🇺
The recent measurements of the masses of the pulsar J00737-3039B and of the companion J1756-2251 and pulsars PSR J1614-2230, PSR J0348-0432 demonstrate the existence of compact stars with masses in a broad range from 1.2 to 2 $M_{⊙}$ . To fulfill the constraint $M_{max} > 2 M_{⊙}$ and to demonstrate the possibility of cooling scenarios for purely hadronic and further for hybrid stars we exploit the stiff DD2 hadronic equation of state producing a maximum neutron star mass $M ≃ 2.43 M_{⊙}$ . We show that the "nuclear medium cooling" scenario for neutron stars comfortably explains the whole set of cooling curves just by a variation of the star masses without the necessity for the occurrence of the direct Urca reaction. To describe the cooling data with the very stiff DD2 equation of state we select a proton gap profile from those exploited in the literature and allow for a variation of the effective pion gap controlling the efficiency of the medium modified Urca process. Fast cooling of young neutron stars like it is seen in the data for Cas A is explained with the DD2 equation of state when the following conditions are provided: the presence of an efficient medium modified Urca process, and a large proton gap at densities $n \leq 2 n_{0}$ vanishing for $n \geq (2.5 - 3) n_{0}$ , where $n_{0}$ is the saturation nuclear density.
Comments:
16 pages, 7 figures, Proceedings of the Conference "Compact Stars in the QCD Phase Diagram IV", September 26-30, 2014, Prerow, Germany
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.04656 [pdf]
1 citation
11
[Submitted on 16 Jul 2015] (cross-list from hep-ph)
Heavy baryons in the large Nc limit
C. Albertus🇪🇸 · E. Ruiz Arriola🇪🇸 · I. P. Fernando🇺🇸 · J. L. Goity🇺🇸
It is shown that in the large Nc limit heavy baryon masses can be estimated quantitatively in a 1/Nc expansion using the Hartree approximation. The results are compared with available lattice calculations for different values of the ratio between the square root of the string tension and the heavy quark mass tension independent of Nc. Using a potential adjusted to agree with the one obtained in lattice QCD, a variational analysis of the ground state spin averaged baryon mass is performed using Gaussian Hartree wave functions. Relativistic corrections through the quark kinetic energy are included. The results provide good estimates for the first sub-leading in 1/Nc corrections.
Comments:
7 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1507.04667 [pdf]
PLB(2015)·2 citations
12
[Submitted on 16 Jul 2015] (cross-list from hep-ph)
Elliptic flow difference of charged pions in heavy-ion collisions
Yoshitaka Hatta🇯🇵 · Akihiko Monnai🇺🇸 · Bo-Wen Xiao🇨🇳
Recently, the STAR collaboration at RHIC has presented experimental evidence for the correlation between the elliptic flow difference of charged pions and charge asymmetry as a possible signal of the chiral magnetic wave. We demonstrate that the STAR results can be understood within the standard viscous hydrodynamics.
Comments:
5 pages, 4 figures; v2: revised version to appear in Nuclear Physics A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1507.04690 [pdf]
NPA(2016)·43 citations

Affiliations

first authorsco-authorsvia INSPIRE

Identifying exotic hidden-charm pentaquarks

Direct mass measurements of Cd isotopes show strong shell gap at N=82

Rotation-induced deep crustal heating of millisecond pulsars

Proton gaps and cooling of neutron stars with a stiff hadronic EoS

Heavy baryons in the large Nc limit

Elliptic flow difference of charged pions in heavy-ion collisions

Affiliations