Nuclear Theory·nucl-th

Tuesday·July 19, 2016

15 papers—6 primary·9 cross-listed

01
Test the chiral magnetic effect with isobaric collisions
Wei-Tian Deng🇨🇳 · Xu-Guang Huang🇺🇸 · Guo-Liang Ma🇨🇳 · Gang Wang🇺🇸
The quark-gluon matter produced in relativistic heavy-ion collisions may contain local domains in which P and CP symmetries are not preserved. When coupled with an external magnetic field, such P- and CP-odd domains will generate electric currents along the magnetic field --- a phenomenon called the chiral magnetic effect (CME). Recently, the STAR Collaboration at RHIC and the ALICE Collaboration at the LHC released data of charge-dependent azimuthal-angle correlators with features consistent with the CME expectation. However, the experimental observable is contaminated with significant background contributions from elliptic-flow-driven effects, which makes the interpretation of the data ambiguous. In this Letter, we show that the collisions of isobaric nuclei, $_{44}^{96}$ Ru + $_{44}^{96}$ Ru and $_{40}^{96}$ Zr + $_{40}^{96}$ Zr, provide an ideal tool to disentangle the CME signal from the background effects. Our simulation demonstrates that the two collision types at $s_{NN} = 200$ GeV have more than $10%$ difference in the CME signal and less than $2%$ difference in the elliptic-flow-driven backgrounds for the centrality range of $20 - 60%$ .
nucl-thhep-phnucl-exPRC(2016)·121 citations
02
Bulk viscosity for pion and nucleon thermal fluctuation in the hadron resonance gas model
Sabyasachi Ghosh🇮🇳 · Sandeep Chatterjee🇮🇳 · Bedangdas Mohanty🇮🇳
We have calculated microscopically bulk viscosity of hadronic matter, where equilibrium thermodynamics for all hadrons in medium are described by Hadron Resonance Gas (HRG) model. Considering pions and nucleons as abundant medium constituents, we have calculated their thermal widths, which inversely control the strength of bulk viscosities for respective components and represent their in-medium scattering probabilities with other mesonic and baryonic resonances, present in the medium. Our calculations show that bulk viscosity increases with both temperature and baryon chemical potential, whereas viscosity to entropy density ratio decreases with temperature and with baryon chemical potential, the ratio increases first and then decreases. The decreasing nature of the ratio with temperature is observed in most of the earlier investigations with few exceptions. We find that the temperature dependence of bulk viscosity crucially depends on the structure of the relaxation time. Along the chemical freeze-out line in nucleus-nucleus collisions with increasing collision energy, bulk viscosity as well as the bulk viscosity to entropy density ratio decreases, which also agrees with earlier references. Our results indicate the picture of a strongly coupled hadronic medium.
nucl-thhep-phPRC(2016)·12 citations
03
Investigation of the Ground and Excited States of the 3H and 4He Nuclei by Using the Methods of Group Theory
S. B. Doma · H. S. El-Gendy
The method of group theory is applied to investigate the ground and the excited states of the triton and helium nuclei by using the translation invariant shell model with basis functions corresponding to even number of quanta of excitations in the range 0 less than or equal to N less than or equal to 20. Accordingly, the ground and first excited state wave functions and energies, the S, P and D state probabilities, the root mean square radius and the magnetic dipole moment of triton have been investigated. Also, the energies and wave functions of the ground and the even parity excited states and the root mean square radius of helium have been investigated. Two residual two body interactions together with two three nucleon interactions have been used in the calculations. Moreover, the convergence of calculations has been examined by extrapolating the results with N less than or equals to 20 step by step to reach N equals to 30 for the two nuclei.
nucl-th0 citations
04
Quest for magicity in hypernuclei
M. Ikram · Bharat Kumar · S. K. Biswal · S. K. Patra
In present study, we search the lambda magic number in hypernuclei within the framework of relativistic mean field theory (RMF) with inclusion of hyperon-nucleon and hyperon-hyperon potentials. Based on one- and two-lambda separation energy and two-lambda shell gap, 2, 8, 14, 18, 20, 28, 34, 40, 50, 58, 68, 70 and 82 are suggested to be the $Λ$ magic number within the present approach. The weakening strength of $Λ$ spin-orbit interaction is responsible for emerging the new lambda shell closure other than the model scheme. The predicted $Λ$ magic numbers are in remarkable agreement with earlier predictions and hypernuclear magicity quite resembles with nuclear magicity. %Our results also support the nuclear magicity, Our results are supported by nuclear magicity, where neutron number N = 34 is experimentally observed as a magic which is one of the $Λ$ closed shell in our predictions. In addition, the stability of hypernuclei is also examined by calculating the binding energy per particle, where Ni hypernucleus is found to be most tightly bound triply magic system in considered hypernuclei. Nucleon and lambda density distributions are observed and it is found that introduced $Λ$ 's have significant impact on total density and reduces the central depression of the core nucleus. Nucleon and lambda mean field potentials and spin-orbit interaction potentials are also observed for predicted triply magic hypernuclei and the addition of $Λ$ 's affect the both the potentials to a large extent. The single-particle energy levels are also analyzed to explain the shell gaps for triply magic multi- $Λ$ hypernuclei.
nucl-thIJMPE(2016)·1 citation
05
Applicability of the continuum-discretized coupled-channels method to the deuteron breakup at low energies
Kazuyuki Ogata · Kazuki Yoshida
We re-examine the deuteron elastic breakup cross sections on 12C and 10Be at low incident energies, for which a serious discrepancy between the continuum-discretized coupled-channels method (CDCC) and the Faddeev-Alt-Grassberger-Sandhas theory (FAGS) was pointed out. We show the closed-channels neglected in the preceding study affect significantly the breakup cross section calculated with CDCC, resulting in good agreement with the result of FAGS.
nucl-thPRC(2016)·25 citations
06
Double scattering production of two positron-electron pairs in ultraperipheral heavy-ion collisions
Mariola Klusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱
We present first measurable predictions for electromagnetic (two-photon) double scattering production of two positron-electron pairs in ultraperipheral heavy-ion collisions at LHC. Measureable cross sections are obtained with realistic cuts on electron/positron (pseudo)rapidities and transverse momenta for the ALICE and ATLAS or CMS experiments. The predictions for total and differential cross sections are presented. We show also two-dimensional distributions in rapidities of the opposite-sign (from the same or different subcollisions) and of the same-sign ( $e^{+} e^{+}$ or $e^{-} e^{-}$ ) electrons and in rapidity distance between them. Expected number of events are presented and discussed. Our calculations strongly suggest that relevant measurements with the help of ATLAS, CMS and ALICE detectors are possible in a near future.
nucl-thhep-exhep-phPLB(2016)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE

Test the chiral magnetic effect with isobaric collisions

Bulk viscosity for pion and nucleon thermal fluctuation in the hadron resonance gas model

Investigation of the Ground and Excited States of the 3H and 4He Nuclei by Using the Methods of Group Theory

Quest for magicity in hypernuclei

Applicability of the continuum-discretized coupled-channels method to the deuteron breakup at low energies

Double scattering production of two positron-electron pairs in ultraperipheral heavy-ion collisions

Affiliations