Nuclear Theory·nucl-th

Friday·May 15, 2020

10 papers—3 primary·7 cross-listed

01
[Submitted on 13 May 2020]
Limitations of the Geiger-Nuttall Law in heavy cluster decay
Omar Nagib · Ahmed M. Hamed
Geiger-Nuttall Law is the simplest relation in radioactive decay relating the half-life and the decay energy. Initially restricted to $α$ decay of individual isotopes, generalizations unifying different isotopes and decay modes under a single set of constant coefficients were subsequently achieved. This motivates investigating to what extent such generalizations are possible. We also examine whether there exists a universal Geiger-Nuttall Law that can simultaneously describe all decay modes and nuclei including heavy clusters. We show that the validity of Geiger-Nuttall Law and its generalizations hinges on the assumption that half-life can be approximated linearly as a function of the square root of the ratio of the decay energy to the Coulomb barrier height. Systematic calculation of the ratio across the nuclear chart for 12 decay modes reveals that it varies over its whole range between 0 and 1. Consequently, no linear approximation can unify all the nuclei and decay modes under a single set of coefficients, and thus no universal Geiger-Nuttall Law is possible in contrast to previous claims. In cluster decay, the ratio varies within 0.6-1 where non-linearity becomes significant such that no generalized Geiger-Nuttall description of heavy clusters is possible. In the ongoing attempts of unification, it might be necessary to go beyond the Geiger-Nuttall Law and incorporate additional terms proportional to the decay energy and/or its square root.
Comments:
12 pages, 8 figures. Same as the published version. Title changed in v3 and v4 (this version)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2005.06578 [pdf]
PRC(2021)·3 citations
02
[Submitted on 14 May 2020]
Framework for Polarized Superfluid Fermion Systems
Aurel Bulgac
I discuss the advantages and disadvantages of several procedures, some known and some new, for constructing stationary states within the mean field approximation for a system with pairing correlations and unequal numbers spin-up and spin-down fermions, using the two chemical potentials framework. One procedure in particular appears to have significant physics advantages over previously suggested in the literature computational frameworks. Moreover, this framework is applicable to study strongly polarized superfluid fermion systems with arbitrarily large polarizations and with arbitrary total particle numbers. These methods are equally applicable to normal systems.
Comments:
13 pages, 5 figures, fix typos, inconsistent notations, figure labels, and a couple of numerical errors in Figs. 4b and 5a, added to additional panels to Fig. 5, extended text and references
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas)
arXiv:
2005.06763 [pdf]
1 citation
03
[Submitted on 13 May 2020]
Exploring the partonic phase at finite chemical potential in and out-of equilibrium
O. Soloveva🇩🇪 · P. Moreau🇺🇸 · L. Oliva🇩🇪 · T. Song🇩🇪 · W. Cassing🇩🇪 · E.Bratkovskaya🇩🇪
We study the influence of the baryon chemical potential $μ_{B}$ on the properties of the Quark-Gluon-Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_{c}$ from lattice Quantum Chromodynamics (QCD). We calculate the transport coefficients such as the ratio of shear viscosity $η$ and bulk viscosity $ζ$ over entropy density $s$ , i.e., $η / s$ and $ζ / s$ in the $(T, μ_{B})$ plane and compare to other model results available at $μ_{B} = 0$ . The out-of equilibrium study of the QGP is performed within the Parton-Hadron-String Dynamics (PHSD) transport approach extended in the partonic sector by explicitly calculating the total and differential partonic scattering cross sections (based on the DQPM propagators and couplings) evaluated at the actual temperature $T$ and baryon chemical potential $μ_{B}$ in each individual space-time cell of the partonic scattering. The traces of their $μ_{B}$ dependences are investigated in different observables for relativistic heavy-ion collisions with a focus on the directed and elliptic flow coefficients $v_{1}, v_{2}$ in the energy range 7.7 GeV $\leq s_{N N} \leq 200$ GeV.
Comments:
11 pages, 4 figures, contribution to the Proceedings of the 36th Winter Workshop on Nuclear Dynamics, 1-7 March 2020, Puerto Vallarta, Maxico. arXiv admin note: substantial text overlap with arXiv:2001.05395
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2005.07028 [pdf]
J.Phys.Conf.Ser.(2020)·3 citations
04
[Submitted on 11 May 2020] (cross-list from hep-ph)
Resonant Neutrino Self-Interactions
Cyril Creque-Sarbinowski🇺🇸 · Jeffrey Hyde🇺🇸 · Marc Kamionkowski🇺🇸
If neutrinos have self-interactions, these will induce scatterings between astrophysical and cosmic neutrinos. Prior work proposed to look for possible resulting resonance features in astrophysical neutrino spectra in order to seek a neutrino self-interaction which can be either diagonal in the neutrino flavor space or couple different neutrino flavors. The calculation of the astrophysical spectra involves either a Monte Carlo simulation or a computationally intensive numerical integration of an integro-partial-differential equation. As a result only limited regions of the neutrino self-interaction parameter space have been explored, and only flavor-diagonal self-interactions have been considered. Here, we present a fully analytic form for the astrophysical neutrino spectra for arbitrary neutrino number and arbitrary self-coupling matrix that accurately obtains the resonance features in the observable neutrino spectra. The results can be applied to calculations of the diffuse supernova neutrino background and of the spectrum from high-energy astrophysical neutrino sources. We illustrate with a few examples.
Comments:
11 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2005.05332 [pdf]
PRD(2021)·41 citations
05
[Submitted on 14 May 2020] (cross-list from hep-ph)
Very heavy flavored dibaryons
Jean-Marc Richard🇫🇷 · Alfredo Valcarce🇪🇸 · Javier Vijande🇪🇸
We explore the possibility of very heavy dibaryons with three charm quarks and three beauty quarks, $bbb ccc$ , using a constituent model which should drive to the correct solution in the limit of hadrons made of heavy quarks. The six-body problem is treated rigorously, in particular taking into account the orbital, color and spin mixed-symmetry components of the wave function. Unlike a recent claim based on lattice QCD, no bound state is found below the lowest dissociation threshold.
Comments:
4 pages, to appear in PRL
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2005.06894 [pdf]
PRL(2020)·41 citations
06
[Submitted on 14 May 2020] (cross-list from hep-ph)
Two-pole structures in QCD: Facts, not fantasy!
Ulf-G. Meißner🇩🇪
The two-pole structure refers to the fact that particular single states in the spectrum as listed in the PDG tables are often two states. The story began with the $Λ (1405)$ , when in 2001, using unitarized chiral perturbation theory, it was observed that there are two poles in the complex plane, one close to the $K ˉ p$ and the other close to the $π Σ$ threshold. This was later understood combining the SU(3) limit and group-theoretical arguments. Different unitarization approaches that all lead to the two-pole structure have been considered in the mean time, showing some spread in the pole positions. This fact is now part of the PDG book, though it is not yet listed in the summary tables. Here, I will discuss the open ends and critically review approaches that can not deal with this issue. In the meson sector some excited charm mesons are good candidates for such a two-pole structure. Next, I consider in detail the $D_{0}^{*} (2300)$ , that is another candidate for this scenario. Combining lattice QCD with chiral unitary approaches in the finite volume, the precise data of the Hadron Spectrum Collaboration for coupled-channel $D π$ , $D η$ , $D_{s} K ˉ$ scattering in the isospin $I = 1/2$ channel indeed reveal its two-pole structure. Further states in the heavy meson sector with $I = 1/2$ exhibiting this phenomenon are predicted, especially in the beauty meson sector. I also discuss the relation of these two-pole structures and the possible molecular nature of the states under consideration.
Comments:
22 pages, 10 figures, invited article for the special issue in "Symmetry" on "Chiral Symmetry in Physics", D. Klabucar (ed.), accepted version
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:
2005.06909 [pdf]
Symmetry(2020)·118 citations
07
[Submitted on 14 May 2020] (cross-list from hep-ph)
Analysis on nonperturbative flavor violation at chiral crossover criticality in QCD
Mamiya Kawaguchi🇨🇳 · Shinya Matsuzaki🇨🇳 · Akio Tomiya🇺🇸
We discuss the violation of quark-flavor symmetry at high temperatures, induced from nonperturbative thermal loop corrections and axial anomaly, based on a three-flavor linear-sigma model including an axial-anomaly induced-flavor breaking term. We employ a nonperturbative analysis following the Cornwall-Jackiw-Tomboulis formalism, and show that the model undergoes a chiral crossover with a pseudo-critical temperature, consistently with lattice observations. We find following features regarding the flavor breaking eminent around and above the pseudo-critical temperature: i) up-and down-quark condensates drop faster than the strange quark's toward the criticality, but still keep nonzero value even going far above the critical temperature; ii) the introduced anomaly-related flavor-breaking effect acts as a catalyzer toward the chiral restoration, and reduces the amount of flavor breaking in the up, down and strange quark condensates; iii) a dramatic deformation for the meson flavor mixing structure is observed, in which the anomaly-induced favor breaking is found to be almost irrelevant; iv) the meson spectroscopy gets corrected by the net nonperturbative flavor breaking effects, where the scalar meson mass hierarchy (inverse mass hierarchy) is significantly altered by the presence of the anomaly-related flavor breaking; v) the topological susceptibility significantly gets the contribution from the surviving strange quark condensate, which cannot be dictated by the chiral perturbation theory, and deviates from the dilute instanton gas prediction. There the anomaly-induced flavor breaking plays a role of the destructive interference for the net flavor violation; vi) the U(1)_A breaking is enhanced by the strange quark condensate, which may account for the tension in the effective U(1)_A restoration observed on lattices with two flavors and 2+1 flavors near the chiral limit.
Comments:
25 pages, 13 figures, minor corrections made, some revision made
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2005.07003 [pdf]
PRD(2021)·18 citations
08
[Submitted on 14 May 2020] (cross-list from hep-ph)
$Z^{0}$ boson associated b-jet production in high-energy nuclear collisions
Sa Wang🇨🇳 · Wei Dai🇨🇳 · Ben-Wei Zhang🇨🇳 · Enke Wang🇨🇳
The production of vector boson tagged heavy quark jets potentially provides new tools to probe the jet quenching effect. In this paper, we present the first theoretical study on the angular correlations ( $Δ ϕ_{b Z}$ ), transverse momentum imbalance ( $x_{b Z}$ ), and nuclear modification factor ( $I_{AA}$ ) of $Z^{0}$ boson tagged b-jets in heavy-ion collisions, which was performed using a Monte Carlo transport model. We find that the medium modification of the $Δ ϕ_{b Z}$ for $Z^{0} +$ b-jet has a weaker dependence on $Δ ϕ_{b Z}$ than that for $Z^{0} +$ jet, and the modification patterns are sensitive to the initial jet $p_{T}$ distribution. Additionally, with the high purity of the quark jet in $Z^{0} +$ (b-)jet production, we calculate the momentum imbalance $x_{b Z}$ and the nuclear modification factor $I_{AA}$ of $Z^{0} +$ b-jet in Pb+Pb collisions. We observe a smaller $Δ ⟨ x_{j Z} ⟩$ and larger $I_{AA}$ of $Z^{0} +$ b-jet in Pb+Pb collisions relative to those of $Z^{0} +$ jet, which may be an indication of the mass effect of jet quenching and can be tested in future measurements.
Comments:
13 pages, 12 figures, 1 table. The version to appear in CPC
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2005.07018 [pdf]
CPC(2023)·19 citations
09
[Submitted on 14 May 2020] (cross-list from hep-ph)
A New Method to Extract Information of Near-Threshold Resonances: Uniformized Pole-Sum Representation of Green's Function and T-matrix
Wren Yamada🇯🇵 · Osamu Morimatsu🇯🇵
We propose a new, simple model-independent method to extract information of near-threshold resonances, such as complex energies and residues. The method is based on the observation that the Green's function and the T-matrix can be represented as the sum of all poles, both bound and resonant poles, in the complex plane of a variable in which the Green's function and the T-matrix are single-valued functions. The symmetries of poles, which arise from the unitarity of the S-matrix, naturally impose the sum to obey the proper threshold behaviors. The imaginary part of Green's function and the T-matrix are directly related to observables such as scattering cross sections or invariant or missing mass distributions of hadron resonances. Thus we can determine their pole positions and residues by fitting their imaginary part to observables. We also test the new method by regarding the imaginary part of the $T$ -matrix calculated exactly in a model theory as virtual experimental data. As a model theory, we take double-channel meson-baryon scatterings in the chiral unitary model with channels, $K N (I = 0)$ , and $π Σ (I = 0)$ . By fitting the imaginary part of the $T$ -matrix calculated in the model theory by that of the uniformized pole-sum, we obtain the pole positions and residues. Comparing the obtained results with those of the exact calculation in the model theory, we conclude that our new method works very well.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2005.07022 [pdf]
PRC(2020)·13 citations
10
[Submitted on 14 May 2020] (cross-list from hep-ph)
Spectrum of the Hidden-Bottom and the Hidden-Charm/Strange Exotics in the Dynamical Diquark Model
Jesse F. Giron🇺🇸 · Richard F. Lebed🇺🇸
The lightest hidden-bottom tetraquarks in the dynamical diquark model fill an $S$ -wave multiplet consisting of 12 isomultiplets. We predict their masses and dominant bottomonium decay channels using a simple 3-parameter Hamiltonian that captures the core fine-structure features of the model, including isospin dependence. The only experimental inputs needed are the corresponding observables for $Z_{b} (10610)$ and $Z_{b} (10650)$ . The mass of $X_{b}$ , the bottom analogue to $X (3872)$ , is highly constrained in this scheme. In addition, using lattice-calculated potentials we predict the location of the center of mass of the $P$ -wave multiplet and find that $Y (10860)$ fits well but the newly discovered $Y (10750)$ does not, more plausibly being a $D$ -wave bottomonium state. Using similar methods, we also examine the lowest $S$ -wave multiplet of 6 $c c ˉ s s ˉ$ states, assuming as in earlier work that $X (3915)$ and $Y (4140)$ are members, and predict the masses and dominant charmonium decay modes of the other states. We again use lattice potentials to compute the centers of mass of higher multiplets, and find them to be compatible with the masses of $Y (4626)$ ( $1 P$ ) and $X (4700)$ ( $2 S$ ), respectively.
Comments:
15 pages, 2 .pdf figures, Small revisions to the Reference section. Version accepted to appear in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2005.07100 [pdf]
PRD(2020)·54 citations

Affiliations

first authorsco-authorsvia INSPIRE