Nuclear Theory·nucl-th

Tuesday·October 9, 2018

12 papers—4 primary·8 cross-listed

01
On Mass correction to Chiral Vortical Effect and Chiral Separation Effect
Shu Lin🇨🇳 · Lixin Yang🇨🇳
We study coefficients of axial chiral vortical effect and chiral separation effect at finite temperature and vector chemical potential in massive theories. We present two independent methods of calculating the coefficients: one from field theory and the other using the mass term in axial anomaly equation. An ambiguity in the integration constant similar to hydrodynamic approach to axial chiral vortical effect exists in the latter, but can be fixed naturally in the presence of mass. We obtain perfect agreement between the methods. The results of axial chiral vortical effect and chiral separation effect indicate that the presence of mass generically suppresses the two coefficients, with less suppression at larger chemical potential. For phenomenologically relevant case of quark gluon plasma with three quark flavor, we find the correction is negligible.
nucl-thhep-phhep-thPRD(2018)·45 citations
02
Predictions of nuclear $β$ -decay half-lives with machine learning and their impacts on $r$ process
Z. M. Niu · H. Z. Liang · B. H. Sun · W. H. Long · Y. F. Niu
Nuclear $β$ decay is a key process to understand the origin of heavy elements in the universe, while the accuracy is far from satisfactory for the predictions of $β$ -decay half-lives by nuclear models up to date. In this letter, we pave a novel way to accurately predict $β$ -decay half-lives with the machine-learning based on the Bayesian neural network, in which the known physics has been explicitly embedded, including the ones described by the Fermi theory of $β$ decay, and the dependence of half-lives on pairing correlations and decay energies. The other potential physics, which is not clear or even missing in nuclear models nowadays, will be learned by the Bayesian neural network. The results well reproduce the experimental data with a very high accuracy and further provide reasonable uncertainty evaluations in half-life predictions. These accurate predictions for half-lives with uncertainties are essential for the $r$ -process simulations.
nucl-thastro-ph.SRnucl-exPRC(2019)·128 citations
03
Uncertainty quantification in nuclear shell model
Sota Yoshida · Noritaka Shimizu · Tomoaki Togashi · Takaharu Otsuka
The uncertainty quantifications of theoretical results are of great importance to make meaningful comparisons of those results with experimental data and to make predictions in experimentally unknown regions. By quantifying uncertainties, one can make more solid statements about, e.g., origins of discrepancy in some quantities between theory and experiment. We propose a novel method for uncertainty quantification for the effective interactions of nuclear shell-model calculations as an example. The effective interaction is specified by a set of parameters, and its probability distribution in the multi-dimensional parameter space is considered. This enables us to quantify the agreement with experimental data in a statistical manner and the resulting confidence intervals show unexpectedly large variations. Moreover, we point out that a large deviation of the confidence interval for the energy in shell-model calculations from the corresponding experimental data can be used as an indicator of some exotic property, e.g. alpha clustering, etc. Other possible applications and impacts are also discussed.
nucl-thnucl-exPRC(2018)·24 citations
04
Wobbling motion in $^{165, 167}$ Lu within a semi-classical framework
A. A. Raduta · R. Poenaru · Al. H. Raduta
The results obtained for $^{165, 167}$ Lu with a semi-classical formalism are presented. Properties like excitation energies for the super-deformed bands TSD1, TSD2, TSD3, in $^{165}$ Lu, and TSD1 and TSD2 for $^{167}$ Lu, inter- and intra-band B(E2) and B(M1), the mixing ratios, transition quadrupole moments are compared either with the corresponding experimental data or with those obtained for $^{163}$ Lu. Also alignments, dynamic moments of inertia, relative energy to a reference energy of a rigid symmetric rotor with an effective moment of inertia and the angle between the angular momenta of the core and odd nucleon were quantitatively studied. One concludes that the semi-classical formalism provides a realistic description of all known wobbling features in $^{165, 167}$ Lu.
nucl-thJ.Phys.G(2018)·13 citations
05
Risk analysis for long term disposal of radioactive nuclear waste
Sabikun Nahar Sadia · Md. Iqbal Hosan · Md. Jafor Dewan · Saikat Ahmed
In this study the technical risk analysis that was conducted using fault trees.With respect to the scenarios in Bangladesh, there is still no concrete proposal about a permanent disposal method, so this analysis is based on the propositions and other historical data. When actual data is produced, this risk analysis technique can then be employed to calculate risks.
↳ physics.soc-phnucl-th0 citations
06
Spectral Representation of Thermal OTO Correlators
Soumyadeep Chaudhuri🇮🇳 · Chandramouli Chowdhury🇮🇳 · R. Loganayagam🇮🇳
We study the spectral representation of finite temperature, out of time ordered (OTO) correlators on the multi-time-fold generalised Schwinger-Keldysh contour. We write the contour-ordered correlators as a sum over time-order permutations acting on a funda- mental array of Wightman correlators. We decompose this Wightman array in a basis of column vectors, which provide a natural generalisation of the familiar retarded-advanced basis in the finite temperature Schwinger-Keldysh formalism. The coefficients of this de- composition take the form of generalised spectral functions, which are Fourier transforms of nested and double commutators. Our construction extends a variety of classical results on spectral functions in the SK formalism at finite temperature to the OTO case.
↳ hep-thcond-mat.stat-mechhep-phnucl-thJHEP(2019)·39 citations
07
Quadrupole moments of spin-1 systems: the rho meson, the S-wave deuteron and some general constraints
A.F. Krutov🇷🇺 · V.E. Troitsky🇷🇺
We costruct the relativistic operator of the quadrupole moment of two-particle composite spin one systems with zero orbital moment of the relative motion and derive explicit analytical expression for the quadrupole moment using the approach to relativistic composite systems based on our version of the instant-form relativistic quantum mechanics (RQM). We calculate the quadrupole moments of the rho meson and of the S-wave deuteron without any free parameters, using our unified pi&rho model (Phys. Rev.D 93, 036007 (2016); 97, 033007 (2018)) and our previous results on deuteron. Our calculation gives Q_rho=-0.158+-0.04 GeV^-2 and Q_d=-1.4*10^-4 GeV^-2. Having in our disposition the rather general form of the quadrupole-moment operator we for the first time formulate the problem of the upper and lower bounds for possible values of the quadrupole moment of a two-particle system with indicated quantum numbers for a large range of constituent masses, and partially solve it.
↳ hep-phnucl-thPRD(2019)·2 citations
08
Hadronic Molecular States Composed of Spin- $\frac{3}{2}$ Singly Charmed Baryons
Bin Yang🇨🇳 · Lu Meng🇨🇳 · Shi-Lin Zhu🇨🇳
We investigate the possible deuteron-like molecules composed of a pair of charmed spin- $\frac{3}{2}$ baryons, or one charmed baryon and one charmed antibaryon within the one-boson-exchange (OBE) model. For the spin singlet and triplet systems, we consider the couple channel effect between systems with different orbital angular momentum. Most of the systems have binding solutions. The couple channel effect plays a significant role in the formation of some loosely bound states. The possible molecular states of $Ω_{c}^{*} Ω_{c}^{*}$ and $Ω_{c}^{*} Ω ˉ_{c}^{*}$ might be stable once produced.
↳ hep-phhep-exhep-latnucl-thEPJA(2019)·12 citations
09
$N Ω$ dibaryon from lattice QCD near the physical point
Takumi Iritani🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Faisal Etminan🇮🇷 · Shinya Gongyo🇯🇵 · Tetsuo Hatsuda🇯🇵 · Yoichi Ikeda🇯🇵 · Takashi Inoue🇯🇵 · Noriyoshi Ishii🇯🇵 · Takaya Miyamoto🇯🇵 · Kenji Sasaki🇯🇵
The nucleon( $N$ )-Omega( $Ω$ ) system in the S-wave and spin-2 channel ( $^{5}$ S $_{2}$ ) is studied from the (2+1)-flavor lattice QCD with nearly physical quark masses ( $m_{π} ≃ 146$ ~MeV and $m_{K} ≃ 525$ ~MeV). The time-dependent HAL QCD method is employed to convert the lattice QCD data of the two-baryon correlation function to the baryon-baryon potential and eventually to the scattering observables. The $N Ω$ ( $^{5}$ S $_{2}$ ) potential, obtained under the assumption that its couplings to the D-wave octet-baryon pairs are small, is found to be attractive in all distances and to produce a quasi-bound state near unitarity: In this channel, the scattering length, the effective range and the binding energy from QCD alone read $a_{0} = 5.30 (0.44) (_{- 0.01}^{+ 0.16})$ ~fm, $r_{eff} = 1.26 (0.01) (_{- 0.01}^{+ 0.02})$ ~fm, $B = 1.54 (0.30) (_{- 0.10}^{+ 0.04})$ ~MeV, respectively. Including the extra Coulomb attraction, the binding energy of $p Ω^{-}$ ( $^{5}$ S $_{2}$ ) becomes $B_{p Ω^{-}} = 2.46 (0.34) (_{- 0.11}^{+ 0.04})$ ~MeV. Such a spin-2 $p Ω^{-}$ state could be searched through two-particle correlations in $p$ - $p$ , $p$ -nucleus and nucleus-nucleus collisions.
↳ hep-lathep-exhep-phnucl-ex+1PLB(2019)·157 citations
10
Does the bottomonium counterpart of $X (3872)$ exist?
Zhi-Yong Zhou🇨🇳 · Dian-Yong Chen🇨🇳 · Zhiguang Xiao🇨🇳
A narrow line shape peak at about 10615 MeV, just above the threshold in the $B B ˉ^{*}$ channel, which can be regarded as the signal of bottomonium counterpart of $X (3872)$ , $X_{b}$ , is predicted by using the extended Friedrichs scheme. Though a virtual state is found at about 10593 MeV in this scheme, we point out that the peak is contributed mainly by the coupling form factor, which comes from the convolution of the interaction term and meson wave functions including the one from $χ_{b 1} (4 P)$ , but not mainly by the virtual-state pole. In this picture, the reason why $X_{b}$ signal is not observed in the $Υ π^{+} π^{-}$ and $Υ π^{+} π^{-} π^{0}$ channels can also be understood. The $χ_{b 1} (4 P)$ mass and width are found to be about 10771 MeV and 6 MeV, respectively and a dynamically generated broad resonance is also found with its mass and width at about 10672 MeV and 78 MeV, respectively. The line shapes of these two states are also affected by the form factor effect. Thus, this study also emphasizes the importance of the structure of the wave functions of high radial excitations in the analysis of the line shapes, and provides a caveat that some signals may be generated from the structures of the form factors rather than from poles.
↳ hep-phhep-exnucl-thPRD(2019)·10 citations
11
Shock waves in colliding Fermi gases at finite temperature
S. Chiacchiera🇬🇧 · D. Davesne🇫🇷 · M. Urban🇫🇷
We study the formation and the dynamics of a shock wave originating from the collision between two ultracold clouds of strongly interacting fermions as observed at a lower temperature in an experiment by Joseph et al. [Phys. Rev. Lett. 106, 150401 (2011)]. We use the Boltzmann equation within the test-particle method to describe the evolution of the system in the normal phase. We also show a direct comparison with the hydrodynamic approach and insist on the necessity of including a shear viscosity and a thermal conductivity term in the equations to prevent unphysical behavior from taking place.
↳ cond-mat.quant-gasnucl-thPRA(2018)·2 citations
12
QCD critical end point from a realistic PNJL model
Kun Xu🇨🇳 · Zhibin Li🇨🇳 · Mei Huang🇨🇳
With parameters fixed by critical temperature and equation of state at zero baryon chemical potential, a realistic Polyakov--Nambu--Jona-Lasinio (rPNJL) model predicts a critical end point of chiral phase transition at $(μ_{B}^{E} = 720 MeV, T^{E} = 93 MeV)$ . The extracted freeze-out line from heavy ion collisions is close to the chiral phase transition boundary in the rPNJL model, and the kurtosis $κ σ^{2}$ of baryon number fluctuations from the rPNJL model along the experimental freeze-out line agrees well with the BES-I measurement. Our analysis shows that the dip structure of measured $κ σ^{2}$ is determined by the relationship between the freeze-out line and chiral phase transition line at low baryon density region, and the peak structure can be regarded as a clean signature for the existence of CEP.
↳ hep-phhep-latnucl-thEPJ Web Conf.(2018)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE