Nuclear Theory·nucl-th

Tuesday·December 8, 2015

13 papers—7 primary·6 cross-listed

01
Progress in Neutron EM Couplings
Igor Strakovsky (GW)🇺🇸 · William Briscoe (GW)🇺🇸 · Alexander Kudryavtsev (ITEP/GW)🇺🇸 · Viacheslav Kulikov (ITEP)🇷🇺 · Maxim Martemianov (ITEP)🇷🇺 · Vladimir Tarasov (ITEP)🇷🇺 · Ron Workman (ITEP)🇺🇸
An overview of the GW SAID and ITEP groups' effort to analyze pion photoproduction on the neutron-target will be given. The disentanglement of the isoscalar and isovector EM couplings of N* and Delta* resonances does require compatible data on both proton and neutron targets. The final-state interaction plays a critical role in the state-of-the-art analysis in extraction of the gn-->piN data from the deuteron target experiments. Then resonance couplings determined by the SAID PWA technique are then compared to previous findings. The neutron program is important component of the current JLab, MAMI-C, SPring-8, ELSA, and ELPH studies.
nucl-thhep-exhep-phnucl-ex1 citation
02
$K ˉ$ induced formation of the $f_{0} (980)$ and $a_{0} (980)$ resonances on proton targets
Ju-Jun Xie🇨🇳 · We-Hong Liang🇨🇳 · Eulogio Oset🇨🇳
We perform a calculation of the cross section for nine reactions induced by $K ˉ$ scattering on protons. The reactions studied are $K^{-} p \to Λ π^{+} π^{-}$ , $K^{-} p \to Σ^{0} π^{+} π^{-}$ , $K^{-} p \to Λ π^{0} η$ , $K^{-} p \to Σ^{0} π^{0} η$ , $K^{-} p \to Σ^{+} π^{-} η$ , $K ˉ^{0} p \to Λ π^{+} η$ , $K ˉ^{0} p \to Σ^{0} π^{+} η$ , $K ˉ^{0} p \to Σ^{+} π^{+} π^{-}$ , $K ˉ^{0} p \to Σ^{+} π^{0} η$ . We find that in the reactions producing $π^{+} π^{-}$ a clear peak for the $f_{0} (980)$ resonance is found, while no trace of $f_{0} (500)$ appears. Similarly, in the cases of $π η$ production a strong peak is found for the $a_{0} (980)$ resonance, with the characteristic strong cusp shape. Cross sections and invariant mass distributions are evaluated which should serve, comparing with future data, to test the dynamics of the chiral unitary approach used for the evaluations and the nature of these resonances.
nucl-thhep-phPRC(2016)·6 citations
03
A simple model for rapidity fluctuations in the initial state of ultra-relativistic heavy-ion collisions
Wojciech Broniowski🇵🇱 · Piotr Bozek🇵🇱
Two-particle pseudorapidity correlations are analyzed in a simple model, where in the initial stage of the reaction multiple sources, extended in rapidity, are created. We show how the fluctuations of the length of the sources in rapidity generate correlations in the initial entropy deposition, which later contribute to the observed longitudinal correlations in hadron production. Our analysis, which is analytic and leads to straightforward formulas, allows us to understand the structure of the correlations, in particular to identify the component related to the fluctuation of the numbers of sources and the component from the length fluctuations. We also present the results in terms of the expansion in the basis of the Legendre polynomials. A number of further effects is discussed, such as smearing of the pseudorapidity distributions or resonance decays. Our results reproduce qualitatively and semiquantitatively the basic features of the recent measurements at the LHC.
nucl-thnucl-exPRC(2016)·23 citations
04
Magnetic Properties of Quantized Vortices in Neutron $^{3} P_{2}$ Superfluids in Neutron Stars
Kota Masuda🇯🇵 · Muneto Nitta🇯🇵
We discuss quantized vortices in neutron $^{3} P_{2}$ superfluids, which are believed to realize in high density neutron matter such as neutron stars. By using the Ginzburg-Landau free energy for $^{3} P_{2}$ superfluids, we determine the ground state in the absence and presence of the external magnetic field, and numerically construct $^{3} P_{2}$ quantized vortices in the absence and presence of the external magnetic field along the vortex axis (poloidal) or angular direction (toroidal). We find in certain situations the spontaneous magnetization of the vortex core, whose typical magnitude is about $1 0^{7 - 8}$ Gauss, but the net magnetic field in a neutron star is negligible because of the ratio of the vortex core size $\sim 10$ fm and the intervortex distance $\sim 1 0^{- 6}$ m in a vortex lattice.
nucl-thastro-ph.HEcond-mat.otherhep-phPRC(2016)·33 citations
05
Core momentum distribution in two-neutron halo nuclei
Lucas A. Souza · Filipe F Bellotti · Marcelo T. Yamashita · Tobias Frederico · Lauro Tomio
The core momentum distribution of a weakly-bound neutron-neutron-core exotic nucleus is computed within a renormalized zero-range three-body model, with interactions in the s-wave channel. The halo wave-function in momentum space is obtained by using as inputs the two-body scattering lengths and the two-neutron separation energy. The core momentum densities are computed for $^{11}$ Li, $^{14}$ Be $^{20}$ C and $^{22}$ C. The model describes the experimental data for $^{11}$ Li, $^{14}$ Be and to some extend $^{20}$ C. The recoil momentum distribution of the $^{20}$ C from the breakup of $^{22}$ C nucleus is computed for different two-neutron separation energies, and from the comparison with recent experimental data the two-neutron separation energy is estimated in the range $100 ≲ S_{2 n} ≲ 400$ KeV. The recoil momentum distribution depends weakly on the neutron- $^{20}$ C scattering length, while the matter radius is strongly sensitive to it. The expected universality of the momentum distribution width is verified by also considering excited states for the system.
nucl-thquant-phPLB(2016)·12 citations
06
Power spectrum of flow fluctuations in relativistic heavy-ion collisions
P. S. Saumia🇮🇳 · Ajit M. Srivastava🇮🇳
We carry out hydrodynamical simulation of the evolution of fluid in relativistic heavy-ion collisions with random initial fluctuations. The time evolution of power spectrum of momentum anisotropies shows very strong correspondence with the physics of cosmic microwave anisotropies as was earlier predicted by some of us. In particular our results demonstrate suppression of superhorizon fluctuations and the correspondence between the location of the first peak in the power spectrum of momentum anisotropies and the length scale of fluctuations and expected freezeout time scale (more precisely, the sound horizon size at freezeout).
nucl-thastro-ph.COhep-phnucl-exMod.Phys.Lett.A(2016)·6 citations
07
Hydrodynamic simulations of relativistic heavy-ion collisions with different lattice QCD calculations of the equation of state
J. Scott Moreland🇺🇸 · Ron A. Soltz🇺🇸
Hydrodynamic calculations of ultra-relativistic heavy ion collisions are performed using the iEBE-VISHNU 2+1D code with fluctuating initial conditions and three different parameterizations of the Lattice QCD equations of state: continuum extrapolations for stout and HISQ/tree actions, as well as the s95p-v1 parameterization based upon calculations using the p4 action. All parameterizations are matched to a hadron resonance gas equation of state at T = 155 MeV, at which point the calculations are continued using the UrQMD hadronic cascade. Calculations for $s_{N N} = 200$ GeV Au+Au collisions in three centrality classes are compared to experimental data for final state particle spectra and anisotropic flow coefficients $v_{2}$ and $v_{3}$ as well as for pion HBT radii. Experimental observables for the stout and HISQ/tree equations of state are observed to differ by less than a few percent for all observables, while the s95p-v1 equation of state generates spectra and flow coefficients which differ by ~10-20%. Calculations in which the HISQ/tree equation of state is sampled from the published error distribution are also observed to differ by less than a few percent.
nucl-thhep-latnucl-exPRC(2016)·59 citations

Affiliations

first authorsco-authorsvia INSPIRE

Progress in Neutron EM Couplings

Kˉ induced formation of the f0​(980) and a0​(980) resonances on proton targets

A simple model for rapidity fluctuations in the initial state of ultra-relativistic heavy-ion collisions

Magnetic Properties of Quantized Vortices in Neutron 3P2​ Superfluids in Neutron Stars

Core momentum distribution in two-neutron halo nuclei

Power spectrum of flow fluctuations in relativistic heavy-ion collisions

Hydrodynamic simulations of relativistic heavy-ion collisions with different lattice QCD calculations of the equation of state

Affiliations

$K ˉ$ induced formation of the $f_{0} (980)$ and $a_{0} (980)$ resonances on proton targets

Magnetic Properties of Quantized Vortices in Neutron $^{3} P_{2}$ Superfluids in Neutron Stars