Nuclear Theory·nucl-th

Tuesday·April 24, 2018

14 papers—8 primary·6 cross-listed

01
Towers of baryons of the $N = 2$ quark model band in the large $N_{c}$ limit
C.T. Willemyns🇦🇷 · N.N. Scoccola🇦🇷
We performed a complete analysis of the spectrum of all the states in the $N = 2$ quark model harmonic oscillator band with $N_{f} = 3$ in the large $N_{c}$ limit including the often disregarded antisymmetric multiplet $[20, 1^{+}]$ . We included configuration mixing effects. We found that the states in the $[56, L^{+}]$ and $[70, L^{+}]$ with $L = 0, 2$ fall into nine towers of degenerate states. We found that nonstrange antisymmetric states fall into three towers and respond to the same structure as the states in the $[70, 1^{-}]$ multiplet. We also showed explicitly the compatibility of these results and the scattering resonance picture.
nucl-thhep-lathep-phPRD(2018)·1 citation
02
Hadron Spectra, Decays and Scattering Properties within Basis Light Front Quantization
James P. Vary🇺🇸 · Lekha Adhikari🇺🇸 · Guangyao Chen🇺🇸 · Shaoyang Jia🇺🇸 · Meijian Li🇺🇸 · Yang Li🇺🇸 · Pieter Maris🇺🇸 · Wenyang Qian🇺🇸 · John R. Spence🇺🇸 · Shuo Tang🇺🇸 · Kirill Tuchin🇺🇸 · Anji Yu🇺🇸 · Xingbo Zhao🇺🇸
We survey recent progress in calculating properties of the electron and hadrons within the Basis Light Front Quantization (BLFQ) approach. We include applications to electromagnetic and strong scattering processes in relativistic heavy ion collisions. We present an initial investigation into the glueball states by applying BLFQ with multigluon sectors, introducing future research possibilities on multi-quark and multi-gluon systems.
nucl-thFew Body Syst.(2018)·16 citations
03
Reexamine the nuclear chiral geometry from the orientation of the angular momentum
Q. B. Chen · J. Meng
The paradox on the previous interpretation for the nuclear chiral geometry based on the effective angle has been clarified by reexamining the system with the particle-hole configuration $π (1 h_{11/2})^{1} \otimes ν (1 h_{11/2})^{- 1}$ and rotor with deformation parameter $γ = 3 0^{\circ}$ . It is found that the paradox is caused by the fact that the angular momentum of the rotor is much smaller than those of the proton and the neutron near the bandhead. Hence, it does not support a chiral rotation interpretation near the bandhead. The nuclear chiral geometry based on the effective angle makes sense only when the angular momentum of the rotor becomes comparable with those of the proton and the neutron at the certain spin region.
nucl-thnucl-exPRC(2018)·41 citations
04
Single- and two-nucleon momentum distributions for local chiral interactions
D. Lonardoni · S. Gandolfi · X. B. Wang · J. Carlson
We present quantum Monte Carlo calculations of the single- and two-nucleon momentum distributions in selected nuclei for $A \leq 16$ . We employ local chiral interactions at next-to-next-to-leading order. We find good agreement at low momentum with the single-nucleon momentum distributions derived for phenomenological potentials. The same agreement is found for the integrated two-nucleon momentum distributions at low relative momentum $q$ and low center-of-mass momentum $Q$ . We provide results for the two-nucleon momentum distributions as a function of both $q$ and $Q$ . The large ratio of $p n$ to $pp$ pairs around $q = 2 f m^{- 1}$ for back-to-back $(Q = 0)$ pairs is confirmed up to $^{16}$ O, and results are compatible with those extracted from available experimental data.
nucl-thPRC(2018)·26 citations
05
Single-pole Nature of the Detectable Lambda(1405)
K. S. Myint🇲🇲 · Y. Akaishi🇯🇵 · M. Hassanvand🇯🇵 · T. Yamazaki🇯🇵
We have investigated the single-pole nature of the detectable Lambda(1405) in detail, by employing a chiral model having double poles of a KbarN-piSigma coupled channel T-matrix. The effects of the 1st pole and the 2nd pole on the observed piSigma mass spectrum in the Lambda(1405) region were analyzed separately by means of the Generalized Optical Potential. It is concluded that the 1st pole is responsible for both peak structures seen in the T(piSigma leftarrow KbarN)(T(21)) and T(piSigma leftarrow piSigma)(T(22)) invariant-mass spectra, and the 2nd pole due to an energy-dependent chiral interaction provides continuum amplitudes affecting the shape of peak structures in experimentally observable spectrum of the Lambda(1405).
nucl-thPTEP(2018)·13 citations
06
Relativistic Dissipative Fluid Dynamics from Non-Equilibrium Statistical Operator
Arus Harutyunyan🇩🇪 · Armen Sedrakian🇩🇪 · Dirk H. Rischke🇩🇪
We present a new derivation of second-order relativistic dissipative fluid dynamics for quantum systems using Zubarev's formalism for the non-equilibrium statistical operator. In particular, we discuss the shear-stress tensor to second order in gradients and argue that the relaxation terms for the dissipative quantities arise from memory effects contained in the statistical operator. We also identify new transport coefficients which describe the relaxation of dissipative processes to second order and express them in terms of equilibrium correlation functions, thus establishing Kubo-type formulae for the second-order transport coefficients.
nucl-thhep-phParticles(2018)·18 citations
07
Construction of a local barK N-pi Sigma-pi Lambda potential and composition of the Lambda(1405)
Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵 · Wolfram Weise🇩🇪
A Kbar N-pi Sigma-pi Lambda coupled-channel potential is constructed on the basis of chiral SU(3) dynamics. Several matching conditions are introduced to formulate an equivalent local potential that reproduces the coupled-channel scattering amplitudes resulting from chiral SU(3)_L times SU(3)_R meson-baryon effective field theory. In contrast to a previously constructed effective single-channel Kbar N potential, the explicit treatment of the pi Sigma channel yields a natural description of the low-mass pole as part of the two-pole structure of the Lambda(1405) resonance. The energy dependence of the potential can now be parametrized with a minimum of polynomial orders. To study the properties of the Lambda(1405) as a quantum-mechanical quasibound state, we derive the normalization condition of its wave function generated by the energy-dependent coupled-channel potential, using the Feshbach projection method. This framework provides an improved understanding of this system from the viewpoint of the compositeness of hadrons. With the properly normalized wave function, we demonstrate and confirm that the high-mass pole of the Lambda(1405) is dominated by the Kbar N component.
nucl-thhep-phPRC(2018)·44 citations
08
Particle number conserving BCS approach in the relativistic mean field model and its application to $^{32 - 74}$ Ca
Rong An · Lisheng Geng · Shisheng Zhang · Lang Liu
A particle number conserving BCS approach (FBCS) is formulated in the relativistic mean field (RMF) model. It is shown that the so-obtained RMF+FBCS model can describe the weak pairing limit. We calculate the ground-state properties of the calcium isotopes $^{32 - 74}$ Ca and compare the results with those obtained from the usual RMF+BCS model. Although the results are quite similar to each other, we observe an interesting phenomenon, i.e., for $^{54}$ Ca, the FBCS approach can enhance the occupation probability of the $2 p_{1/2}$ single particle level and slightly increases its radius, compared with the RMF+BCS model. This leads to an unusual scenario that although $^{54}$ Ca is more bound with a spherical configuration but the corresponding size is not the most compact one. We anticipate that such a phenomenon might happen for other neutron rich nuclei and should be checked by further more systematic studies.
nucl-thnucl-exCPC(2018)·12 citations
09
Lattice QCD and heavy ion collisions: a review of recent progress
Claudia Ratti🇺🇸
In the last few years, numerical simulations of QCD on the lattice have reached a new level of accuracy. A wide range of thermodynamic quantities is now available in the continuum limit and for physical quark masses. This allows a comparison with measurements from heavy ion collisions for the first time. Furthermore, calculations of dynamical quantities are also becoming available. The combined effort from first principles and experiment allows us to gain an unprecedented understanding of the properties of quark-gluon plasma. I will review the state-of-the-art results from lattice simulations and connect them to the experimental information from RHIC and the LHC.
↳ hep-lathep-phnucl-thRept.Prog.Phys.(2018)·272 citations
10
Electrical conductivity of Hot and Dense QCD matter at RHIC BES energies: A Color String Percolation Approach
Pragati Sahoo🇮🇳 · Swatantra Kumar Tiwari🇮🇳 · Raghunath Sahoo🇮🇳
Recently, transport coefficients viz. shear viscosity, electrical conductivity etc. of strongly interacting matter produced in heavy-ion collisions have drawn considerable interest. We study the normalised electrical conductivity ( $σ_{el}$ /T) of hot QCD matter as a function of temperature (T) using the Color String Percolation Model (CSPM). We also study the temperature dependence of shear viscosity and its ratio with electrical conductivity for the QCD matter. We compare CSPM estimations with various existing results and lattice Quantum Chromodynamics (lQCD) predictions with (2+1) dynamical flavours. We find that $σ_{el}$ /T in CSPM has a very weak dependence on the temperature. We compare CSPM results with those obtained in Boltzmann Approach to Multi-Parton Scatterings (BAMPS) model. A good agreement is found between CSPM results and predictions of BAMPS with fixed strong coupling constant.
↳ hep-phhep-exnucl-exnucl-thPRD(2018)·21 citations
11
Analyses of multiplicity distributions and Bose-Einstein correlations at the LHC using negative binomial distribution and generalized Glauber-Lachs formula
Minoru Biyajima🇯🇵 · Takuya Mizoguchi🇯🇵
This study aims to analyze the data on multiplicity distributions and Bose-Einstein correlations collected at the LHC by the ATLAS and CMS Collaborations using a double-generalized Glauber-Lachs formula (D-GGL) and double-negative binomial distribution (D-NBD). From this investigation, it can be inferred that the D-GGL formula performs as effectively as the D-NBD. Moreover, our results show that the parameters estimated in multiplicity distributions (MD) (P(n)) are related to those contained in the BEC formula.
↳ hep-phnucl-thEPJA(2018)·7 citations
12
Matching of transverse momentum dependent distributions at twist-3
Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇩🇪
We derive the leading order matching of the quark generated polarized transverse momentum dependent (TMD) distributions onto the collinear functions at small values of the transverse distance. Starting from the very definition of the TMD operator and performing the light-cone operator product expansion up to twist-3 order, we evaluate each distribution directly in position space. We primarily consider the cases of Sivers, Boer-Mulders and worm-gear functions. The effects of the TMD process dependence on the matching are explicitly shown. We also discuss the moments of TMD distributions which can be relevant for lattice calculations.
↳ hep-phhep-exhep-latnucl-ex+1EPJC(2018)·47 citations
13
Photoneutron cross sections for Ni isotopes: Toward understanding $(n, γ)$ cross sections relevant to the weak s-process nucleosynthesis
H. Utsunomiya🇯🇵 · T. Renstrøm🇳🇴 · G. M. Tveten🇳🇴 · S. Goriely🇧🇪 · S. Katayama🇯🇵 · T. Ari-izumi🇯🇵 · D. Takenaka🇯🇵 · D. Symochko🇩🇪 · B. V. Kheswa🇳🇴 · V.W. Ingeberg🇳🇴 · T. Glodariu🇷🇴 · Y.-W. Lui🇺🇸 and 10 other authors
Photoneutron cross sections were measured for $^{58}$ Ni, $^{60}$ Ni, $^{61}$ Ni, and $^{64}$ Ni at energies between the one-neutron and two-neutron thresholds using quasi-monochromatic $γ$ -ray beams produced in laser Compton-scattering at the NewSUBARU synchrotron radiation facility. The new photoneutron data are used to extract the $γ$ -ray strength function above the neutron threshold complementing the information obtained by the Oslo method below the threshold. We discuss radiative neutron capture cross sections and the Maxwellian-averaged cross sections for Ni isotopes including $^{63}$ Ni, a branching point nucleus along the weak s-process path. The cross sections are calculated with the experimentally constrained $γ$ -ray strength functions from the Hartree-Fock-Bogolyubov plus quasi-particle-random phase approximation based on the Gogny D1M interaction for both $E 1$ and $M 1$ components and supplemented with the $M 1$ upbend.
↳ nucl-exnucl-thPRC(2018)·22 citations
14
Covariant quark model for the electromagnetic structure of light nucleon resonances
G. Ramalho🇧🇷
We present estimates from the covariant spectator quark model for the electromagnetic transition form factors for the resonances $N (1440) \frac{1}{2}^{+}$ , $N (1535) \frac{1}{2}^{-}$ , $N (1520) \frac{3}{2}^{-}$ and $Δ (1232) \frac{3}{2}^{+}$ , at intermediate and large square momentum transfer ( $Q^{2}$ ). The calculations associated to the $N (1440) \frac{1}{2}^{+}$ , $N (1535) \frac{1}{2}^{-}$ and $N (1520) \frac{3}{2}^{-}$ states are based exclusively on the parametrizations derived for the nucleon. In the case of the $Δ (1232) \frac{3}{2}^{+}$ (isospin 3/2), we use lattice QCD data to estimate the radial structure, and take into account the well known effects associated with the pion cloud dressing of the baryons. Our estimates are based mainly on the valence quark degrees of freedom and are in good agreement with the data for $Q^{2} > 2$ GeV $^{2}$ , with a few exceptions. The present predictions can be tested in a near future for large $Q^{2}$ at the Jefferson Lab -- 12 GeV upgrade.
↳ hep-phhep-exhep-latnucl-ex+10 citations

Affiliations

first authorsco-authorsvia INSPIRE