Nuclear Theory·nucl-th

Tuesday·September 19, 2017

5 papers—2 primary·3 cross-listed

01
Nuclear mass parabola and its applications
Junlong Tian · Di Yuan · Yunyi Cui · Yun Huang · Ning Wang
We propose a method to extract the properties of the isobaric mass parabola based on the total double $β$ decay energies of isobaric nuclei. Two important parameters of the mass parabola, the location of the most $β$ -stable nuclei $Z_{A}$ and the curvature parameter $b_{A}$ , are obtained for 251 A values based on the total double $β$ decay energies of nuclei compiled in AME2016 database.The advantage of this approach is that we can remove the pairing energy term $P_{A}$ caused by odd-even variation, and the mass excess $M (A, Z_{A})$ of the most stable nuclide for mass number $A$ in the performance process, which are used in the mass parabolic fitting method. The Coulomb energy coefficient $a_{c} = 0.6910$ MeV is determined by the mass difference relation of mirror nuclei, and the symmetry energy coefficient is also studied by the relation $a_{sym} (A) = 0.25 b_{A} Z_{A}$ .
nucl-thCPC(2019)·2 citations
02
Radiative Capture of Cold Neutrons by Protons and Deuteron Photodisintegration with Twisted Beams
Andrei Afanasev · Valery G. Serbo · Maria Solyanik
We consider two basic nuclear reactions: Radiative capture of neutrons by protons, $n + p \to γ + d$ and its time-reversed counterpart, photodisintegration of the deuteron, $γ + d \to n + p$ . In both of these cases we assume that the incoming beam of neutrons or photons is "twisted" by having an azimuthal phase dependence, {\it i.e.}, it carries an additional angular momentum along its direction of propagation. Taking a low-energy limit of these reactions, we derive relations between corresponding transition amplitudes and cross sections with plane-wave beams and twisted beams. Implications for experiments with twisted cold neutrons and photon beams are discussed.
nucl-thJ.Phys.G(2018)·38 citations
03
Electromagnetic fields in small systems from a multiphase transport model
Xin-Li Zhao🇨🇳 · Yu-Gang Ma🇨🇳 · Guo-Liang Ma🇨🇳
We calculate the electromagnetic fields generated in small systems by using a multiphase transport (AMPT) model. Compared to $A + A$ collisions, we find that the absolute electric and magnetic fields are not small in $p$ +Au and $d$ +Au collisions at energies available at the BNL Relativistic Heavy Ion Collider and in $p$ +Pb collisions at energies available at the CERN Large Hadron Collider. We study the centrality dependencies and the spatial distributions of electromagnetic fields. We further investigate the azimuthal fluctuations of the magnetic field and its correlation with the fluctuating geometry using event-by-event simulations. We find that the azimuthal correlation $⟨ cos 2 (Ψ_{B} - Ψ_{2}) ⟩$ between the magnetic field direction and the second harmonic participant plane is almost zero in small systems with high multiplicities, but not in those with low multiplicities. This indicates that the charge azimuthal correlation, $⟨ cos (ϕ_{α} + ϕ_{β} - 2 Ψ_{R P}) ⟩$ , is not a valid probe to study the chiral magnetic effect (CME) in small systems with high multiplicities. However, we suggest searching for possible CME effects in small systems with low multiplicities.
↳ hep-phnucl-exnucl-thPRC(2018)·28 citations
04
Relating Quark Confinement and Chiral Symmetry Breaking in QCD
Hideo Suganuma (1) · Takahiro M. Doi (2) · Krzysztof Redlich · Chihiro Sasaki (3) ((1) Kyoto U. · (2) RIKEN · (3) Wroclaw U.)
We study the relation between quark confinement and chiral symmetry breaking in QCD. Using lattice QCD formalism, we analytically express the various "confinement indicators", such as the Polyakov loop, its fluctuations, the Wilson loop, the inter-quark potential and the string tension, in terms of the Dirac eigenmodes. In the Dirac spectral representation, there appears a power of the Dirac eigenvalue $λ_{n}$ such as $λ_{n}^{N_{t} - 1}$ , which behaves as a reduction factor for small $λ_{n}$ . Consequently, since this reduction factor cannot be cancelled, the low-lying Dirac eigenmodes give negligibly small contribution to the confinement quantities,while they are essential for chiral symmetry breaking. These relations indicate no direct, one-to-one correspondence between confinement and chiral symmetry breaking in QCD. In other words, there is some independence of quark confinement from chiral symmetry breaking, which can generally lead to different transition temperatures/densities for deconfinement and chiral restoration. We also investigate the Polyakov loop in terms of the eigenmodes of the Wilson, the clover and the domain-wall fermion kernels, respectively, and find the similar results. The independence of quark confinement from chiral symmetry breaking seems to be natural, because confinement is realized independently of quark masses and heavy quarks are also confined even without the chiral symmetry.
↳ hep-lathep-phhep-thnucl-thJ.Phys.G(2017)·25 citations
05
The low-temperature behavior of the quark-meson model
Ralf-Arno Tripolt🇮🇹 · Bernd-Jochen Schaefer🇩🇪 · Lorenz von Smekal🇩🇪 · Jochen Wambach🇮🇹
We revisit the phase diagram of strong-interaction matter for the two-flavor quark-meson model using the Functional Renormalization Group. In contrast to standard mean-field calculations, an unusual phase structure is encountered at low temperatures and large quark chemical potentials. In particular, we identify a regime where the pressure decreases with increasing temperature and discuss possible reasons for this unphysical behavior.
↳ hep-phhep-thnucl-thPRD(2018)·80 citations

Affiliations

first authorsco-authorsvia INSPIRE

Nuclear mass parabola and its applications

Radiative Capture of Cold Neutrons by Protons and Deuteron Photodisintegration with Twisted Beams

Electromagnetic fields in small systems from a multiphase transport model

Relating Quark Confinement and Chiral Symmetry Breaking in QCD

The low-temperature behavior of the quark-meson model

Affiliations