Nuclear Theory·nucl-th

Monday·December 5, 2016

10 papers—8 primary·2 cross-listed

01
Charmed mesons at finite temperature and chemical potential
Fernando E. Serna🇧🇷 · Gastão Krein🇧🇷
We compute the masses of the pseudoscalar mesons $π^{+}$ , $K^{0}$ and $D^{+}$ at finite temperature and baryon chemical potential. The computations are based on a symmetry- preserving Dyson-Schwinger equation treatment of a vector-vector four quark contact interaction. The results found for the temperature dependence of the meson masses are in qualitative agreement with lattice QCD data and QCD sum rules calculations. The chemical potential dependence of the masses provide a novel prediction of the present computation.
nucl-thEPJ Web Conf.(2017)·7 citations
02
Anomalies in weak decays of H-like ions
Francesco Giacosa · Giuseppe Pagliara
We investigate the emergence of oscillations in the decay law of unstable systems. We discuss in particular the case of the so-called GSI anomaly seen in the electron capture decays of H-like ions and prove that such oscillations cannot be explained by neutrino oscillations. We then discuss how such anomalies could be intimately related to the decay law of unstable systems in the case in which their spectral function deviates from a Breit-Wigner shape.
nucl-thquant-phNucl.Instrum.Meth.B(2017)·1 citation
03
Probing the resonance in the Dirac equation with quadruple-deformed potentials by complex momentum representation method
Zhi Fang · Min Shi · Jian-You Guo · Zhong-Ming Niu · Haozhao Liang · Shi-Sheng Zhang
Resonance plays critical roles in the formation of many physical phenomena, and many techniques have been developed for the exploration of resonance. In a recent letter [Phys. Rev. Lett. 117, 062502 (2016)], we proposed a new method for probing single-particle resonances by solving the Dirac equation in complex momentum representation for spherical nuclei. Here, we extend this method to deformed nuclei with theoretical formalism presented. We elaborate numerical details, and calculate the bound and resonant states in $^{37}$ Mg. The results are compared with those from the coordinate representation calculations with a satisfactory agreement. In particular, the present method can expose clearly the resonant states in complex momentum plane and determine precisely the resonance parameters for not only narrow resonances but also broad resonances that were difficult to obtain before.
nucl-thquant-phPRC(2017)·32 citations
04
Production of neutron-rich isotopes around N=126 in multinucleon transfer reactions
Zhao-Qing Feng
The multinucleon transfer reactions has been investigated within the dinuclear system model. The nucleon transfer is coupled to the dissipation of relative motion energy and angular momentum by solving a set of microscopically derived master equations. A barrier distribution approach is implemented in the model in order to including the contributions of different orientations and dynamical effects. The available data of fragment production via multinucleon transfer reactions could be understood with the model for the reactions of $^{136}$ Xe + $^{198}$ Pt/ $^{208}$ Pb near Coulomb barrier energies. It is found that the production of heavy neutron-rich nuclei weakly depends on the incident energy. However, the yields of proton-rich nuclei increase with the incident energy.
nucl-thPRC(2017)·100 citations
05
Charged pions tagged with polarized photons probing strong CP violation in a chiral-imbalance medium
Mamiya Kawaguchi🇯🇵 · Masayasu Harada🇯🇵 · Shinya Matsuzaki🇯🇵 · Ruiwen Ouyang🇨🇳
It is expected that in a hot QCD system, a local parity-odd domain can be produced due to nonzero chirality, which is induced from the difference of winding numbers carried by the gluon topological configuration (QCD sphaleron). This local domain is called the chiral-imbalance medium characterized by nonzero chiral chemical potential, which can be interpreted as the time variation of the strong CP phase. We find that the chiral chemical potential generates the parity breaking term in the electromagnetic form factor of charged pions. Heavy ion collision experiments could observe the phenomenological consequence of this parity-odd form factor through the elastic scattering of a pion and a photon in the medium. Then we quantify the asymmetry rate of the parity violation by measuring the polarization of the photon associated with the pion, and discuss how it could be measured in a definite lab frame. We roughly estimate the typical size of the asymmetry, just by picking up the pion resonant process, and find that the signal can be sufficiently larger than possible background events from parity-breaking electroweak process. Our findings might provide a novel possibility to make a manifest detection for the remnant of the strong CP violation.
nucl-thhep-phnucl-exPRC(2017)·12 citations
06
Deeply quasi-bound state in single- and double- $K ˉ$ nuclear clusters
Sajjad Marri🇮🇷 · Seyed Zafarollah Kalantari🇮🇷 · Jafar Esmaili🇮🇷
New calculations of the quasi-bound state positions in $K^{-} K^{-} pp$ kaonic nuclear cluster are performed using non-relativistic four-body Faddeev-type equations in AGS form. The corresponding separable approximation for the integral kernels in the three- and four-body kaonic clusters is obtained by using the Hilbert-Schmidt expansion procedure. Different phenomenological models of $K ˉ N - π Σ$ potentials with one- and two-pole structure of $Λ$ (1405) resonance and separable potential models for $K ˉ$ - $K ˉ$ and nucleon-nucleon interactions, are used. The dependence of the resulting four-body binding energy on models of $K ˉ N - π Σ$ interaction is investigated. We obtained the binding energy of the $K^{-} K^{-} pp$ quasi-bound state $\sim$ 80-94 MeV with the phenomenological $K ˉ N$ potentials. The width is about $\sim$ 5-8 MeV for the two-pole models of the interaction, while the one-pole potentials give $\sim$ 24-31 MeV width.
nucl-thEPJA(2016)·17 citations
07
Bridging the gap between event-by-event fluctuation measurements and theory predictions in relativistic nuclear collisions
P. Braun-Munzinger🇩🇪 · A. Rustamov🇩🇪 · J. Stachel🇩🇪
We develop methods to deal with non-dynamical contributions to event-by-event fluctuation measurements of net-particle numbers in relativistic nuclear collisions. These contributions arise from impact parameter fluctuations and from the requirement of overall net-baryon number or net-charge conservation and may mask the dynamical fluctuations of interest, such as those due to critical endpoints in the QCD phase diagram. Within a model of independent particle sources we derive formulae for net-particle fluctuations and develop a rigorous approach to take into account contributions from participant fluctuations in realistic experimental environments and at any cumulant order. Interestingly, contributions from participant fluctuations to the second and third cumulants of net-baryon distributions are found to vanish at mid-rapidity for LHC energies while higher cumulants of even order are non-zero even when the net-baryon number at mid-rapidity is zero. At lower beam energies the effect of participant fluctuations increases and induces spurious higher moments. The necessary corrections become large and need to be carefully taken into account before comparison to theory. We also provide a procedure for selecting the optimal phase-space coverage of particles for fluctuation analyses and discuss quantitatively the necessary correction due to global charge conservation.
nucl-thnucl-exNPA(2017)·153 citations
08
Conditions for the existence of stable strange quark matter
Nicola Andrea Dondi🇮🇹 · Alessandro Drago🇮🇹 · Giuseppe Pagliara🇮🇹
We discuss the possible existence of absolutely stable strange quark matter within three different types of chiral models. We will show that confinement plays a crucial role in determining the conditions for the Bodmer-Witten hypothesis to hold true. We discuss also which are the phenomenological signatures, related to measurements of masses and radii of compact stars, which would prove the existence of strange quark stars.
nucl-thastro-ph.HEhep-phEPJ Web Conf.(2017)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE