Nuclear Theory·nucl-th

Thursday·February 15, 2018

11 papers—5 primary·6 cross-listed

01
One-proton emission from the $_{Λ}^{6}$ Li hypernucleus
Tomohiro Oishi🇮🇹
One-proton (1p) radioactive emission under the influence of the $Λ^{0}$ -hyperon inclusion is discussed. I investigate the hyper-1p emitter, $_{Λ}^{6}$ Li, with a time-dependent three-body model. Two-body interactions for $α$ -proton and $α$ - $Λ^{0}$ subsystems are determined consistently to their resonant and bound energies, respectively. For a proton- $Λ^{0}$ subsystem, a contact interaction, which can be linked to the vacuum-scattering length of the proton- $Λ^{0}$ scattering, is employed. A noticeable sensitivity of the 1p-emission observables to the scattering length of the proton- $Λ^{0}$ interaction is shown. The $Λ^{0}$ -hyperon inclusion leads to a remarkable fall of the 1p-resonance energy and width from the hyperon-less $α$ -proton resonance. For some empirical values of the proton- $Λ^{0}$ scattering length, the 1p-resonance width is suggested to be of the order of $0.1 - 0.01$ MeV. Thus, the 1p emission from $_{Λ}^{6}$ Li may occur in the timescale of $1 0^{- 20} - 1 0^{- 21}$ seconds, which is sufficiently shorter than the self-decay lifetime of $Λ^{0}$ , $1 0^{- 10}$ seconds. By taking the spin-dependence of the proton- $Λ^{0}$ interaction into account, a remarkable split of the $J^{π} = 1^{-}$ and $2^{-}$ 1p-resonance states is predicted. It is also suggested that, if the spin-singlet proton- $Λ^{0}$ interaction is sufficiently attractive, the 1p emission from the $1^{-}$ ground state is forbidden. From these results, I conclude that the 1p emission can be a suitable phenomenon to investigate the basic properties of the hypernuclear interaction, for which a direct measurement is still difficult.
nucl-thnucl-exPRC(2018)·3 citations
02
Chemical freezeout parameters within generic nonextensive statistics
Abdel Nasser Tawfik (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo)🇪🇬 · Hayam Yassin🇪🇬 · Eman R. Abo Elyazeed (Ain Shams U., Cairo, WLCAPP, Cairo)🇪🇬
The particle production in relativistic heavy-ion collisions seems to be created in a dynamically disordered system which can be best described by an extended exponential entropy. In distinguishing between the applicability of this and Boltzmann-Gibbs (BG) in generating various particle-ratios, generic (non)extensive statistics (GNS) is introduced to the hadron resonance gas model. Accordingly, the degree of (non)extensivity is determined by the possible modifications in the phase space. Both BG extensivity and Tsallis nonextensivity are included as very special cases defined by specific values of the equivalence classes $(c, d)$ . We found that the particle ratios at energies ranging between $3.8$ and $2760$ GeV are best reproduced by nonextensive statistics, where $c$ and $d$ range between $\sim 0.9$ and $\sim 1$ . The present work aims at illustrating that the proposed approach is well capable to manifest the statistical nature of the system on interest. We don't aim at highlighting deeper physical insights. In other words, while the resulting nonextensivity is neither BG nor Tsallis, the freezeout parameters are found very compatible with BG and accordingly with the well-known freezeout phase-diagram, which is in an excellent agreement with recent lattice calculations. We conclude that the particle production is nonextensive but should not necessarily be accompanied by a radical change in the intensive or extensive thermodynamic quantities, such as internal energy and temperature. Only, the two critical exponents defining the equivalence classes $(c, d)$ are the physical parameters characterizing the (non)extensivity.
nucl-thhep-phhep-thIndian J.Phys.(2018)·12 citations
03
Axial Charge Fluctuation and Chiral Magnetic Effect from Stochastic Hydrodynamics
Shu Lin🇨🇳 · Li Yan🇨🇦 · Gui-Rong Liang🇨🇳
The amount of axial charge produced in heavy ion collisions is one of the key quantities in understanding chiral magnetic effect. Current phenomenological studies assume large axial charge chemical potential $μ_{5}$ produced in Glasma phase and assume the conservation of axial charge throughout the evolution, which is valid in the long relaxation time limit. Based on the solution of stochastic hydrodynamics with phenomenological parameters, our study suggests that the situation of heavy ion collisions may be close to the opposite limit, in which axial charge fluctuation approaches thermodynamic limit. Using $μ_{5}$ set by the thermodynamic limit for chiral magnetic effect and a background from parity-even $v_{1}$ , we obtain a reasonable description of the centrality dependence of charged particle correlation measured in experiment.
nucl-thhep-phnucl-exPRC(2018)·22 citations
04
Interacting hadron resonance gas model in K-matrix formalism
Ashutosh Dash🇮🇳 · Subhasis Samanta🇮🇳 · Bedangadas Mohanty🇮🇳
An extension of Hadron Resonance Gas (HRG) model is constructed to include interactions using relativistic virial expansion of partition function. The non-interacting part of the expansion contains all the stable baryons and mesons and the interacting part contains all the higher mass resonances which decay into two stable hadrons. The virial coefficients are related to the phase shifts which are calculated using K-matrix formalism in the present work. We have calculated various thermodynamics quantities like pressure, energy density, and entropy density of the system. A comparison of thermodynamic quantities with non interacting HRG model, calculated using the same number of hadrons, shows that the results of above formalism are larger. A good agreement between equation of state calculated in K-matrix formalism and lattice QCD simulations is observed. Specifically the lattice QCD calculated interaction measure is well described in our formalism. We have also calculated second order fluctuations and correlations of conserved charges in K-matrix formalism. We observe a good agreement of second order fluctuations and baryon-strangeness correlation with lattice data below the cross-over temperature.
nucl-thhep-phPRC(2018)·40 citations
05
Dynamical and statistical bimodality in nuclear fragmentation
S.Mallik🇮🇳 · G. Chaudhuri🇮🇳 · F. Gulminelli🇫🇷
The origin of bimodal behavior in the residue distribution experimentally measured in heavy ion reactions is reexamined using Boltzmann-Uehling-Uhlenbeck simulations. We suggest that, depending on the incident energy and impact parameter of the reaction, both entrance channel and exit channel effects can be at the origin of the observed behavior. Specifically, fluctuations in the reaction mechanism induced by fluctuations in the collision rate, as well as thermal bimodality directly linked to the nuclear liquid-gas phase transition are observed in our simulations. Both phenomenologies were previously proposed in the literature, but presented as incompatible and contradictory interpretations of the experimental measurements. These results indicate that heavy ion collisions at intermediate energies can be viewed as a powerful tool to study both bifurcations induced by out-of-equilibrium critical phenomena, as well as finite size precursors of thermal phase transitions.
nucl-thnucl-exPRC(2018)·14 citations
06
Heavy Ion Collisions: The Big Picture, and the Big Questions
Wit Busza🇺🇸 · Krishna Rajagopal🇺🇸 · Wilke van der Schee🇺🇸
Heavy ion collisions quickly form a droplet of quark-gluon plasma (QGP) with a remarkably small viscosity. We give an accessible introduction to how to study this smallest and hottest droplet of liquid made on earth and why it is so interesting. The physics of heavy ions ranges from highly energetic quarks and gluons described by perturbative QCD to a bath of strongly interacting gluons at lower energy scales. These gluons quickly thermalize and form QGP, while the energetic partons traverse this plasma and end in a shower of particles called jets. Analyzing the final particles in a variety of different ways allows us to study the properties of QGP and the complex dynamics of multi-scale processes in QCD which govern its formation and evolution, providing what is perhaps the simplest form of complex quantum matter that we know of. Much remains to be understood, and throughout the review big open questions will be encountered.
↳ hep-phhep-thnucl-exnucl-thAnn.Rev.Nucl.Part.Sci.(2018)·1140 citations
07
Neutron Star Mergers Chirp About Vacuum Energy
Csaba Csáki🇺🇸 · Cem Eröncel🇺🇸 · Jay Hubisz🇺🇸 · Gabriele Rigo🇺🇸 · John Terning🇺🇸
Observations of gravitational waves from neutron star mergers open up novel directions for exploring fundamental physics: they offer the first access to the structure of objects with a non-negligible contribution from vacuum energy to their total mass. The presence of such vacuum energy in the inner cores of neutron stars occurs in new QCD phases at large densities, with the vacuum energy appearing in the equation of state for a new phase. This in turn leads to a change in the internal structure of neutron stars and influences their tidal deformabilities which are measurable in the chirp signals of merging neutron stars. By considering three commonly used neutron star models we show that for large chirp masses the effect of vacuum energy on the tidal deformabilities can be sizable. Measurements of this sort have the potential to provide a first test of the gravitational properties of vacuum energy independent from the acceleration of the Universe, and to determine the size of QCD contributions to the vacuum energy.
↳ astro-ph.HEhep-phnucl-thJHEP(2018)·28 citations
08
Frontiers in Nuclear, Heavy Ion and Strong Field Physics
Tamas Biró🇭🇺 · Carsten Greiner🇩🇪 · Berndt Müller🇺🇸 · Johann Rafelski🇺🇸 · Horst Stöcker🇩🇪
An introduction describing Walter Greiner's scientific life for the topical volume to be published by EPJA
↳ physics.hist-phnucl-thEPJA(2018)·1 citation
09
Hadronic Paschen-Back effect
Sachio Iwasaki🇯🇵 · Makoto Oka🇯🇵 · Kei Suzuki🇯🇵 · Tetsuya Yoshida🇯🇵
We find a novel phenomenon induced by the interplay between a strong magnetic field and finite orbital angular momenta in hadronic systems, which is analogous to the Paschen-Back effect observed in the field of atomic physics. This effect allows the wave functions to drastically deform. We discuss anisotropic decay from the deformation as a possibility to measure the strength of the magnetic field in heavy-ion collision at LHC, RHIC and SPS, which has not experimentally been measured. As an example we investigate charmonia with a finite orbital angular momentum in a strong magnetic field. We calculate the mass spectra and mixing rates. To obtain anisotropic wave functions, we apply the cylindrical Gaussian expansion method, where the Gaussian bases to expand the wave functions have different widths along transverse and longitudinal directions in the cylindrical coordinate.
↳ hep-phhep-exnucl-exnucl-th+1PLB(2019)·17 citations
10
The relativistic chiral Lagrangian for decuplet and octet baryons at next-to-leading order
Måns Holmberg🇸🇪 · Stefan Leupold (Uppsala U.)🇸🇪
A complete and minimal relativistic Lagrangian is constructed at next-to-leading order for SU(3) chiral perturbation theory in the presence of baryon octet and baryon decuplet states. The Lagrangian has 13 terms for the pure decuplet sector, 6 terms for the transition sector from baryon octet to decuplet and (as already known from the literature) 16 terms for the pure octet sector. The minimal field content of 25 of these terms is meson-baryon four-point interactions. 3 terms give rise to the mass splitting for baryon octet and decuplet states, respectively. 2 terms give rise to overall mass shifts. 4 terms provide anomalous magnetic moments and a decuplet-to-octet magnetic transition moment. 1 term leads to an axial vector transition moment. It is shown that meson-baryon three-point coupling constants come in at leading order whereas no additional one appears in the minimal Lagrangian at next-to-leading order. Those low-energy constants that give rise to mass splitting and magnetic moments, respectively, are determined. Predictions are provided for radiative decays of decuplet to octet baryons.
↳ hep-phnucl-thEPJA(2018)·36 citations
11
First Extraction of Transversity from a Global Analysis of Electron-Proton and Proton-Proton Data
Marco Radici🇮🇹 · Alessandro Bacchetta🇮🇹
We present the first extraction of the transversity distribution in the framework of collinear factorization based on the global analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. For the first time, the chiral-odd transversity is extracted from a global analysis similar to what is usually done for the chiral-even spin-averaged and helicity distributions. The knowledge of transversity is important for, among other things, detecting possible signals of new physics in high-precision low-energy experiments.
↳ hep-phhep-exnucl-exnucl-thPRL(2018)·145 citations

Affiliations

first authorsco-authorsvia INSPIRE