Nuclear Theory·nucl-th

Tuesday·December 8, 2015

13 papers—7 primary·6 cross-listed

01
[Submitted on 4 Dec 2015]
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.
Comments:
6 pages, 7 figures, 1 table; Hadron 2015 Proceedings. arXiv admin note: substantial text overlap with arXiv:1501.02510
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1512.01557 [pdf]
1 citation
02
[Submitted on 7 Dec 2015]
$K ˉ$ 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.
Comments:
7 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1512.01888 [pdf]
PRC(2016)·6 citations
03
[Submitted on 7 Dec 2015]
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.
Comments:
12 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1512.01945 [pdf]
PRC(2016)·23 citations
04
[Submitted on 7 Dec 2015]
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.
Comments:
16 pages, 12 figures and 3 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); cond-mat.other (cond-mat.other); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1512.01946 [pdf]
PRC(2016)·33 citations
05
[Submitted on 7 Dec 2015]
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.
Comments:
16 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1512.02070 [pdf]
PLB(2016)·12 citations
06
[Submitted on 7 Dec 2015]
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).
Comments:
4 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1512.02136 [pdf]
Mod.Phys.Lett.A(2016)·6 citations
07
[Submitted on 7 Dec 2015]
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.
Comments:
11 pages, 9 figures. Calculations of the HBT radii have been updated to include increased statistics and correct an inconsistency in the UrQMD particle output
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex)
arXiv:
1512.02189 [pdf]
PRC(2016)·59 citations
08
[Submitted on 4 Dec 2015] (cross-list from astro-ph.SR)
SMWDs as SGRs/AXPs and the lepton number violation
J. Adam Jr.🇨🇿 · V.B. Belyaev🇷🇺 · P. Ricci🇮🇹 · F. Šimkovic🇷🇺 · E. Truhlík🇨🇿
Possible nature of strongly magnetized white dwarfs (SMWDs) is studied. It is shown that for relatively low values of the equatorial surface magnetic field $B \sim 1 0^{9} - 1 0^{11}$ G they can be good candidates for soft gamma-ray repeaters and anomalous X-ray pulsars (SGRs/AXPs). For the case of iron SMWDs the influence of a neutrinoless electron to positron conversion on the SGRs/AXPs luminosity is estimated.
Comments:
4 pages, contribution to the proceedings of the Workshop on calculation of double-beta-decay matrix elements (MEDEX'15), Prague, 9-12 June 2015, eds. O. Civitarese, I. Stekl and J. Suhonen
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1512.01564 [pdf]
AIP Conf.Proc.(2015)·0 citations
09
[Submitted on 5 Dec 2015] (cross-list from cond-mat.str-el)
Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling: I. Kinetic equation and anomalous Hall and spin-Hall effects
K. Morawetz
The coupled kinetic equation for density and spin Wigner functions are derived including spin-orbit coupling, electric and magnetic field as well as selfconsistent Hartree meanfields suited for SU(2) transport. The interactions are assumed to be with scalar and magnetic impurities as well as scalar and spin-flip potentials among the particles. The spin-orbit interaction is used in a form suitable to solid state physics with Rashba or Dresselhaus coupling, graphene, extrinsic spin-orbit coupling as well as effective nuclear matter coupling. The deficiencies of the two-fluid model are worked out consisting in the appearance of an effective in-medium spin-precession. The stationary solution of all these systems shows a band splitting controlled by an effective medium-dependent Zeeman field. The selfconsistent precession direction is discussed and a cancellation of linear spin-orbit coupling at zero temperature is reported. The precession of spin around this effective direction caused by spin-orbit coupling leads to anomalous charge and spin currents in an electric field. Anomalous Hall conductivity is shown to consists of the known results obtained from Kubo formula or Berry phases and a new symmetric part interpreted as inverse Hall effect. Analogously the spin-Hall and inverse spin-Hall effect of spin currents are discussed which are present even without magnetic fields showing a spin accumulation triggered by currents. The analytical dynamical expressions for zero temperature are derived and discussed in dependence on the magnetic field and effective magnetizations. The anomalous Hall and spin-Hall effect changes sign at higher than a critical frequency dependent on the relaxation time.
Comments:
PRB in print 2015
Subjects:
Strongly Correlated Electrons (cond-mat.str-el); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); Plasma Physics (physics.plasm-ph)
arXiv:
1512.01660 [pdf]
PRB(2015)·9 citations
10
[Submitted on 5 Dec 2015] (cross-list from cond-mat.str-el)
Kinetic theory of spin-polarized systems in electric and magnetic fields with spin-orbit coupling: II. RPA response functions and collective modes
K. Morawetz
The spin and density response functions in the random phase approximation (RPA) are derived by linearizing the kinetic equation including a magnetic field, the spin-orbit coupling, and mean fields with respect to an external electric field. Different polarization functions appear describing various precession motions showing Rabi satellites due to an effective Zeeman field. The latter turns out to consist of the mean-field magnetization, the magnetic field, and the spin-orbit vector. The collective modes for charged and neutral systems are derived and a threefold splitting of the spin waves dependent on the polarization and spin-orbit coupling is shown. The dielectric function including spin-orbit coupling, polarization and magnetic fields is presented analytically for long wave lengths and in the static limit. The dynamical screening length as well as the long-wavelength dielectric function shows an instability in charge modes, which are interpreted as spin segregation and domain formation. The spin response describes a crossover from damped oscillatory behavior to exponentially damped behavior dependent on the polarization and collision frequency. The magnetic field causes ellipsoidal trajectories of the spin response to an external electric field and the spin-orbit coupling causes a rotation of the spin axes. The spin-dephasing times are extracted and discussed in dependence on the polarization, magnetic field, spin-orbit coupling and single-particle relaxation times.
Comments:
PRB 2015
Subjects:
Strongly Correlated Electrons (cond-mat.str-el); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); Plasma Physics (physics.plasm-ph)
arXiv:
1512.01661 [pdf]
PRB(2015)·2 citations
11
[Submitted on 7 Dec 2015] (cross-list from hep-ph)
Strong decay patterns of the hidden-charm tetraquarks
Li Ma🇨🇳 · Wei-Zhen Deng🇨🇳 · Xiao-Lin Chen🇨🇳 · Shi-Lin Zhu🇨🇳
With the spin rearrangement, we have performed a comprehensive investigation of the decay patterns of the S-wave tetraquarks and P-wave tetraquarks where the P-wave excitation exists either between the diquark and anti-diquark pair or inside the diquark. Especially, we compare the decay patterns of $Y (4260)$ with different inner structures such as the conventional charmonium, the molecule, the P-wave tetraquark and the hybrid charmonium. We notice the $J / ψ π π$ mode is suppressed in the heavy quark symmetry limit if $Y (4260)$ is a molecular state. Moreover the hybrid charmonium and hidden-charm tetraquark have very similar decay patterns. Both of them decay into the $J / ψ π π$ and open charm modes easily. We also discuss the decay patterns of $X (3872)$ , $Y (4360)$ , and several charged states such as $Z_{c} (4020)$ . The $h_{c} π^{\pm}$ decay mode disfavors the tetraquark assumption of $Z_{c} (4020)$ .
Comments:
35 pages, 7 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1512.01938 [pdf]
9 citations
12
[Submitted on 7 Dec 2015] (cross-list from physics.atm-clus)
Observation of the Efimov state of the helium trimer
Maksim Kunitski · Stefan Zeller · Jörg Voigtsberger · Anton Kalinin · Lothar Ph. H. Schmidt · Markus Schöffler · Achim Czasch · Wieland Schöllkopf · Robert E. Grisenti · Till Jahnke · Dörte Blume · Reinhard Dörner
Quantum theory dictates that upon weakening the two-body interaction in a three-body system, an infinite number of three-body bound states of a huge spatial extent emerge just before these three-body states become unbound. Three helium atoms have been predicted to form a molecular system that manifests this peculiarity under natural conditions without artificial tuning of the attraction between particles by an external field. Here we report experimental observation of this long predicted but experimentally elusive Efimov state of $^{4}$ He $_{3}$ by means of Coulomb explosion imaging. We show spatial images of an Efimov state, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away.
Subjects:
physics.atm-clus (physics.atm-clus); Quantum Gases (cond-mat.quant-gas); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1512.02036 [pdf]
Science(2015)·110 citations
13
[Submitted on 7 Dec 2015] (cross-list from physics.atom-ph)
Enhanced spin-dependent parity non-conservation effect in the $7 s^{2} S_{1/2} \to 6 d^{2} D_{5/2}$ transition in Fr: A possibility for unambiguous detection of nuclear anapole moment
B. K. Sahoo · T. Aoki · B. P. Das · Y. Sakemi
Employing the relativistic coupled-cluster method, comparative studies of the parity non-conserving electric dipole amplitudes for the $7 s^{2} S_{1/2} \to 6 d^{2} D_{5/2}$ transitions in $^{210}$ Fr and $^{211}$ Fr isotopes have been carried out. It is found that these transition amplitudes, sensitive only to the nuclear spin dependent effects, are enhanced by more than 3 orders compared to the low-lying $S - D_{5/2}$ transitions in Ba $^{+}$ and Ra $^{+}$ owing to the very large contributions from the electron core-polarization effects in Fr. This translates to a relatively large and, in principle, measurable induced light shift, which would be a signature of nuclear spin dependent parity nonconservation that is dominated by the nuclear anapole moment in a heavy atom like Fr. A plausible scheme to measure this quantity using the Cyclotron and Radioisotope Center (CYRIC) facility at Tohoku University has been outlined.
Comments:
5 pages, 2 tables and 1 figure
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph); physics.optics (physics.optics)
arXiv:
1512.02055 [pdf]
PRA(2016)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE