Nuclear Theory·nucl-th

Friday·August 5, 2016

7 papers—3 primary·4 cross-listed

01
[Submitted on 3 Aug 2016]
Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization
Sushant N. More🇺🇸
We investigate two distinct sources of uncertainty in low-energy nuclear physics calculations and develop ways to account for them. Harmonic oscillator basis expansions are widely used in ab-initio nuclear structure calculations. Finite computational resources usually require that the basis be truncated before observables are fully converged, necessitating reliable extrapolation schemes. We show that a finite oscillator basis effectively imposes a hard-wall boundary condition. We accurately determine the position of the hard-wall as a function of oscillator space parameters, derive extrapolation formulas for the energy and other observables, and discuss the extension of this approach to higher angular momentum. Nucleon knockout reactions have been widely used to study and understand nuclear properties. Such an analysis implicitly assumes that the effects of the probe can be separated from the physics of the target nucleus. This factorization between nuclear structure and reaction components depends on the renormalization scale and scheme, and has not been well understood. But it is potentially critical for interpreting experiments and for extracting process-independent nuclear properties. We use similarity renormalization group (SRG) transformations to systematically study the scale dependence of factorization for the simplest knockout process of deuteron electrodisintegration. We find that the extent of scale dependence depends strongly on kinematics, but in a systematic way. Based on examination of the relevant overlap matrix elements, we are able to qualitatively explain and even predict the nature of scale dependence based on the kinematics under consideration.
Comments:
PhD thesis
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1608.01385 [pdf]
0 citations
02
[Submitted on 4 Aug 2016]
Deformation-induced splitting of isoscalar E0 giant resonance: Skyrme random-phase-approximation analysis
J. Kvasil · V.O. Nesterenko · A. Repko · W. Kleinig · P.-G. Reinhard
The deformation-induced splitting of isoscalar giant monopole resonance (ISGMR) is systematically analyzed in a wide range of masses covering medium, rare-earth, actinide, and superheavy axial deformed nuclei. The study is performed within the fully self-consistent quasiparticle random-phase-approximation (QRPA) method based on the Skyrme functional. Two Skyrme forces, one with a large (SV-bas) and one with a small (SkP) nuclear incompressibility, are considered. The calculations confirm earlier results that, due to the deformation-induced E0-E2 coupling, the isoscalar E0 resonance attains a double-peak structure and significant energy upshift. Our results are compared with available analytic estimations. Unlike earlier studies, we get a smaller energy difference between the lower and upper peaks and thus a stronger E0-E2 coupling. This in turn results in more pumping of E0 strength into the lower peak and more pronounced splitting of ISGMR. We also discuss widths of the peaks and their negligible correlation with deformation.
Comments:
11 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1608.01483 [pdf]
PRC(2016)·26 citations
03
[Submitted on 4 Aug 2016]
The attribute of rotational profile to the hyperon puzzle in the prediction of heaviest compact star
M. Bhuyan · B. V. Carlson · S.-G. Zhou · S. K. Patra
In this theoretical study, we report an investigation of the equations of state (EoSs) ofhyper-nuclear matter and its composition as a function of density within the framework of effective field theory motivated relativistic mean field model. We have used G2 force parameter along with various hyperon-meson coupling ratios by allowing the mixing and the breaking of SU(6) symmetry to predict the EoSs, keeping the nucleonic coupling constant intact. We have estimated the properties of non-rotating and rapidly rotating configuration of compact stars by employing four different representative sets of equations of state. The obtained results of the mass and radius for the compact stars are compared with the recent mass observations. Further, we have studied the stability and sensitivity of rotational frequency (at sub-millisecond period) on the configuration of the compact stars, because the angular frequency is significantly smaller than the mass-shedding (Keplerian) frequency in slow rotation regime. Moreover, the yield of hyperon as a function of density for various hyperon-meson couplings are also estimated.
Comments:
19 pages, 6 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1608.01639 [pdf]
IJMPE(2017)·8 citations
04
[Submitted on 3 Aug 2016] (cross-list from hep-ph)
Canonical description of the new LHCb resonances
Pablo G. Ortega🇪🇸 · Jorge Segovia🇩🇪 · David R. Entem🇪🇸 · Francisco Fernández🇪🇸
The LHCb Collaboration has recently observed four $J / ψ ϕ$ structures called $X (4140)$ , $X (4274)$ , $X (4500)$ and $X (4700)$ in the $B^{+} \to J / ψ ϕ K^{+}$ decays. We study them herein using a nonrelativistic constituent quark model in which the degrees of freedom are quark-antiquark and meson-meson components. The $X (4140)$ resonance appears as a cusp in the $J / ψ ϕ$ channel due to the near coincidence of the $D_{s}^{\pm} D_{s}^{*\pm}$ and $J / ψ ϕ$ mass thresholds. The remaining three $X (4274)$ , $X (4500)$ and $X (4700)$ appear as conventional charmonium states with quantum numbers $3^{3} P_{1}$ , $4^{3} P_{0}$ and $5^{3} P_{0}$ , respectively; and whose masses and widths are slightly modified due to their coupling with the corresponding closest meson-meson thresholds. A particular feature of our quark model is a lattice-based screened linear confining interaction that has been constrained in the light quark sector and usually produces higher excited heavy-quark states with lower masses than standard quark model predictions.
Comments:
7 pages, 8 tables, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1608.01325 [pdf]
PRD(2016)·62 citations
05
[Submitted on 4 Aug 2016] (cross-list from nucl-ex)
Effects of Longitudinal Asymmetry in Heavy-Ion Collisions
Rashmi Raniwala (University of Rajasthan)🇮🇳 · Sudhir Raniwala (University of Rajasthan)🇺🇸 · Constantin Loizides (LBNL)🇺🇸
In collisions of identical nuclei at a given impact parameter, the number of nucleons participating in the overlap region of each nucleus can be unequal due to nuclear density fluctuations. The asymmetry due to the unequal number of participating nucleons, referred to as longitudinal asymmetry, causes a shift in the center of mass rapidity of the participant zone. The information of the event asymmetry allows us to isolate and study the effect of longitudinal asymmetry on rapidity distribution of final state particles. In a Monte Carlo Glauber model the average rapidity-shift is found to be almost linearly related to the asymmetry. Using toy models, as well as Monte Carlo data for Pb-Pb collisions at 2.76 TeV generated with HIJING, two different versions of AMPT and DPMJET models, we demonstrate that the effect of asymmetry on final state rapidity distribution can be quantitatively related to the average rapidity shift via a third-order polynomial with a dominantly linear term. The coefficients of the polynomial are proportional to the rapidity shift with the dependence being sensitive to the details of the rapidity distribution.Experimental estimates of the spectator asymmetry through the measurement of spectator nucleons in a Zero Degree Calorimeter may hence be used to further constrain the initial conditions in ultra-relativistic heavy-ion collisions.
Comments:
8 pages, 7 captioned figures, 1 table, final version
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1608.01428 [pdf]
PRC(2018)·11 citations
06
[Submitted on 4 Aug 2016] (cross-list from cond-mat.quant-gas)
Heteronuclear Efimov scenario with positive intraspecies scattering length
Juris Ulmanis · Stephan Häfner · Rico Pires · Eva D. Kuhnle · Yujun Wang · Chris H. Greene · Matthias Weidemüller
We investigate theoretically and experimentally the heteronuclear Efimov scenario for a three-body system that consists of two bosons and one distinguishable particle with positive intraspecies scattering lengths. The three-body parameter at the three-body scattering threshold and the scaling factor between consecutive Efimov resonances are found to be controlled by the scattering length between the two bosons, approximately independent of short-range physics. We observe two excited-state Efimov resonances in the three-body recombination spectra of an ultracold mixture of fermionic $^{6}$ Li and bosonic $^{133}$ Cs atoms close to a Li-Cs Feshbach resonance, where the Cs-Cs interaction is positive. Deviation of the obtained scaling factor of 4.0(3) from the universal prediction of 4.9 and the absence of the ground state Efimov resonance shed new light on the interpretation of the universality and the discrete scaling behavior of heteronuclear Efimov physics.
Comments:
6 pages, 3 figures, additional supplemental material
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
arXiv:
1608.01477 [pdf]
PRL(2016)·21 citations
07
[Submitted on 4 Aug 2016] (cross-list from hep-ph)
Photoproduction of the scalar mesons $f_{0} (500)$ and $f_{0} (980)$ off the nucleon
Je-Hee Lee🇰🇷 · Hyun-Chul Kim🇰🇷 · Sang-Ho Kim🇰🇷 · Hui-Young Ryu🇰🇷 · Byung-Geel Yu🇰🇷
We investigate photoproduction of the scalar mesona off the nucleon, using the effective Lagrangians and the Regge approach. We first study $f_{0} (980)$ photoproduction, replacing the Feynman propagator with the Regge ones for the $ρ$ -meson exchange in the $t$ -channel. The model parameters are fixed by reproducing the experimental data on the differential cross section. We then apply the same method to $f_{0} (500)$ or $σ$ photoproduction with the same parameters for the Regge propagator. Since the threshold energy of the $f_{0} (500)$ production is rather low, $N^{*}$ resonances, which can decay into the nucleon and two pions in the isoscalar and scalar state, can come into play in the $s$ -channel. To examine the effects of the $N^{*}$ resonances, we set up two models to look into the respective contribution of the $N^{*}$ resonances. We find that in particular $N^{*} (1440)$ and $N^{*} (1680)$ play important roles in $f_{0} (500)$ photoproduction. We discuss the physical implications of the present results.
Comments:
15 pages, 8 figures. Final version accepted for publication in PTEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1608.01508 [pdf]
PTEP(2017)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization

Deformation-induced splitting of isoscalar E0 giant resonance: Skyrme random-phase-approximation analysis

The attribute of rotational profile to the hyperon puzzle in the prediction of heaviest compact star

Canonical description of the new LHCb resonances

Effects of Longitudinal Asymmetry in Heavy-Ion Collisions

Heteronuclear Efimov scenario with positive intraspecies scattering length

Photoproduction of the scalar mesons f0​(500) and f0​(980) off the nucleon

Affiliations

Photoproduction of the scalar mesons $f_{0} (500)$ and $f_{0} (980)$ off the nucleon