Nuclear Theory·nucl-th

Wednesday·January 27, 2016

5 papers—3 primary·2 cross-listed

01
Cluster-shell competition and its effect on the $E 0$ transition probability in $^{20}$ Ne
N. Itagaki · H. Matsuno
$^{20}$ Ne has been known as a typical example of a nucleus with $α$ cluster structure ( $^{16}$ O+ $α$ structure). However according to the spherical shell model, the spin-orbit interaction acts attractively for four nucleons outside of the $^{16}$ O core, and this spin-orbit effect cannot be taken into account in the simple $α$ cluster models. We investigate how the $α$ cluster structure competes with independent particle motions of these four nucleons. The antisymmetrized quasi-cluster model (AQCM) is a method to describe a transition from the $α$ cluster wave function to the $j j$ -coupling shell model wave function. In this model, the cluster-shell transition is characterized by only two parameters; $R$ representing the distance between clusters and $Λ$ describing the breaking of $α$ clusters, and the contribution of the spin-orbit interaction, very important in the $j j$ -coupling shell model, can be taken into account by changing $α$ clusters to quasi clusters. In this article, based on AQCM, we apply $^{16}$ O plus one quasi cluster model for $^{20}$ Ne. Here we focus on the $E 0$ transition matrix element, which has been known as the quantity characterizing the cluster structure. The $E 0$ transition matrix elements are sensitive to the change of the wave functions from $α$ cluster to $j j$ -coupling shell model.
nucl-thnucl-ex0 citations
02
Theoretical study on nuclear structure by the multiple Coulomb scattering and magnetic scattering of relativistic electrons
Jian Liu🇨🇳 · Xin Zhang🇨🇳 · Chang Xu🇨🇳 · Zhongzhou Ren🇨🇳
Electron scattering is an effective method to study the nuclear structure. For the odd- $A$ nuclei with proton holes in the outmost orbits, we investigate the contributions of proton holes to the nuclear quadrupole moments $Q$ and magnetic moments $μ$ by the multiple Coulomb scattering and magnetic scattering. The deformed nuclear charge densities are constructed by the relativistic mean-field (RMF) models. Comparing the theoretical Coulomb and magnetic form factors with the experimental data, the nuclear quadrupole moments $Q$ and nuclear magnetic moments $μ$ are investigated. From the electron scattering, the wave functions of the proton holes of odd- $A$ nuclei can be tested, which can also reflect the validity of the nuclear structure model.
nucl-thNPA(2016)·10 citations
03
Light-by-light scattering in ultraperipheral PbPb collisions at the Large Hadron Collider
Mariola Klusek-Gawenda🇵🇱 · Piotr Lebiedowicz🇵🇱 · Antoni Szczurek🇵🇱
We calculate cross sections for diphoton production in (semi)exclusive $P b P b$ collisions, relevant for the LHC. The calculation is based on equivalent photon approximation in the impact parameter space. The cross sections for elementary $γ γ \to γ γ$ subprocess are calculated including two different mechanisms. We take into account box diagrams with leptons and quarks in the loops. In addition, we consider a vector-meson dominance (VDM-Regge) contribution with virtual intermediate hadronic (vector-like) excitations of the photons. We get much higher cross sections in $P b P b$ collisions than in earlier calculation from the literature. This opens a possibility to study the $γ γ \to γ γ$ (quasi)elastic scattering at the LHC. We present many interesting differential distributions which could be measured by the ALICE, CMS or ATLAS Collaborations at the LHC. We study whether a separation or identification of different components (boxes, VDM-Regge) is possible. We find that the cross section for elastic $γ γ$ scattering could be measured in the heavy-ion collisions for subprocess energies smaller than $W_{γ γ} \approx 15 - 20$ GeV.
nucl-thhep-exhep-phPRC(2016)·119 citations
04
Kinetic freeze-out temperature and flow velocity extracted from transverse momentum spectra of final-state light flavor particles produced in collisions at RHIC and LHC
Hua-Rong Wei🇨🇳 · Fu-Hu Liu🇨🇳 · Roy A. Lacey🇺🇸
The transverse momentum spectra of final-state light flavor particles produced in proton-proton (p-p), copper-copper (Cu-Cu), gold-gold (Au-Au), lead-lead (Pb-Pb), and proton-lead (p-Pb) collisions for different centralities at relativistic heavy ion collider (RHIC) and large hadron collider (LHC) energies are studied in the framework of a multisource thermal model. The experimental data measured by the STAR, CMS, and ALICE Collaborations are consistent with the results calculated by the multi-component Erlang distribution and Tsallis Statistics. The effective temperature and real temperature (kinetic freeze-out temperature) of interacting system at the stage of kinetic freeze-out, the mean transverse flow velocity and mean flow velocity of particles, and the relationships between them are extracted. The dependences of effective temperature and mean (transverse) momentum on rest mass, moving mass, centrality, and center-of-mass energy, and the dependences of kinetic freeze-out temperature and mean (transverse) flow velocity on centrality, center-of-mass energy, and system size are obtained.
↳ hep-phnucl-exnucl-thEPJA(2016)·43 citations
05
Event patterns extracted from transverse momentum and rapidity spectra of Z bosons and quarkonium states produced in pp and Pb-Pb collisions at LHC
Ya-Hui Chen🇨🇳 · Fu-Hu Liu🇨🇳 · Roy A. Lacey🇺🇸
Transverse momentum ( $p_{T}$ ) and rapidity ( $y$ ) spectra of $Z$ bosons and quarkonium states (some charmonium $c c ˉ$ mesons such as $J / ψ$ and $ψ (2 S)$ , and some bottomonium $b b ˉ$ mesons such as $Υ (1 S)$ , $Υ (2 S)$ , and $Υ (3 S)$ ) produced in proton-proton ( $pp$ ) and lead-lead (Pb-Pb) collisions at the large hadron collider (LHC) are uniformly described by a hybrid model of two-component Erlang distribution for $p_{T}$ spectrum and two-component Gaussian distribution for $y$ spectrum. The former distribution results from a multisource thermal model, and the latter one results from the revised Landau hydrodynamic model. The modelling results are in agreement with the experimental data measured in $pp$ collisions at center-of-mass energies $s = 2.76$ and 7 TeV, and in Pb-Pb collisions at center-of-mass energy per nucleon pair $s_{N N} = 2.76$ TeV. Based on the parameter values extracted from $p_{T}$ and $y$ spectra, the event patterns (particle scatter plots) in two-dimensional $p_{T}$ - $y$ space and in three-dimensional velocity space are obtained.
↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2016)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

Cluster-shell competition and its effect on the E0 transition probability in 20Ne

Theoretical study on nuclear structure by the multiple Coulomb scattering and magnetic scattering of relativistic electrons

Light-by-light scattering in ultraperipheral PbPb collisions at the Large Hadron Collider

Kinetic freeze-out temperature and flow velocity extracted from transverse momentum spectra of final-state light flavor particles produced in collisions at RHIC and LHC

Event patterns extracted from transverse momentum and rapidity spectra of Z bosons and quarkonium states produced in pp and Pb-Pb collisions at LHC

Affiliations

Cluster-shell competition and its effect on the $E 0$ transition probability in $^{20}$ Ne