Nuclear Theory·nucl-th

Thursday·July 26, 2018

11 papers—5 primary·6 cross-listed

01
[Submitted on 24 Jul 2018]
Symmetry Restoration in Mixed-Spin Paired Heavy Nuclei
Ermal Rrapaj🇨🇦 · A. O. Macchiavelli🇺🇸 · Alexandros Gezerlis🇨🇦
The nature of the nuclear pairing condensates in heavy nuclei, specifically neutron-proton (spin-triplet), versus identical-particle (spin-singlet) pairing has been an active area of research for quite some time. In this work, we probe three candidates that should display spin-triplet, spin-singlet, and mixed-spin pairing. Using theoretical approaches such as the gradient method and symmetry restoration techniques, we find the ground state of these nuclei in Hartree-Fock-Bogoliubov theory and compute ground-state to ground-state pair-transfer amplitudes to neighbouring isotopes while simultaneously projecting to specific particle number and nuclear spin values. We identify specific reactions for future experimental research that could shed light on spin-triplet and mixed-spin pairing.
Subjects:
Nuclear Theory (nucl-th); Superconductivity (cond-mat.supr-con)
arXiv:
1807.09294 [pdf]
PRC(2019)·10 citations
02
[Submitted on 24 Jul 2018]
Photon radiation from heavy-ion collisions in the $s_{N N} = 19 - 200$ GeV regime
Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Scott McDonald🇨🇦 · Jean-François Paquet🇺🇸 · Chun Shen🇺🇸
We present calculations of prompt and thermal photon production in Au-Au collisions at $s_{N N} = 19 - 200$ ~GeV. We discuss features of the spacetime profile of the plasma relevant for electromagnetic emission. We highlight how the suppression of prompt photon production at low $s_{N N}$ can provide a window to measure thermal photons in low collision energies.
Comments:
4 pages, 5 figures, contribution to Quark Matter 2018 proceedings
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.09326 [pdf]
NPA(2019)·11 citations
03
[Submitted on 24 Jul 2018]
Effects of nonlocality of nuclear potentials on direct capture reactions
Yuan Tian · D.Y. Pang · Zhongyu Ma
Calculations of the direct radiative capture reactions are made for the $^{48}$ Ca $(n, γ)^{49}$ Ca, $^{7}$ Li $(n, γ)^{8}$ Li and $^{12}$ C $(p, γ)^{13}$ N reactions with the Perey-Buck type nonlocal potentials using a potential model. Our results reproduce the experimental data reasonably well. From comparisons with results obtained by using local potentials, it is found that the cross sections of direct capture reactions may change by around 25\% due to the nonlcality of nuclear potentials.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.09395 [pdf]
PRC(2018)·13 citations
04
[Submitted on 25 Jul 2018]
Zero-sound in nuclear matter with the asymmetry parameter $- 1 \leq β \leq 1$
V. A. Sadovnikova (Petersburg Nuclear Physics Institute)🇷🇺
Results for the frequencies of zero-sound excitations in the isospin asymmetric nuclear matter are presented for the different parameters of asymmetry -1\leq\beta\leq 1. The dispersion equations are constructed within the random phase approximation. We use the effective Landau-Migdal quasiparticle interaction with the special isospin dependence of the phase volume in the normalization factor C_0. In the paper we present zero-sound branches of the dispersion equation solutions in the symmetric, asymmetric and neutron matter. The branches correspond to the different channels of decay of the zero-sound excitation in the nuclear matter or nuclei. In the asymmetric nuclear matter we obtain three branches of solutions on the physical and unphysical sheets of the complex frequency plane, \omega_{s\,\tau}(k,\beta), \tau=p,n,np. We demonstrate the change of branches with \beta and conversion of the three branches into two branches in symmetric nuclear matter (\beta=0) and into one branch in the neutron matter (\beta=1).
Comments:
27 pages, 12+2 figures, 2 figures added
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.09580 [pdf]
1 citation
05
[Submitted on 25 Jul 2018]
Correlating Schiff moments in the light actinides with octupole moments
Jacek Dobaczewski🇬🇧 · Jonathan Engel🇺🇸 · Markus Kortelainen🇫🇮 · Pierre Becker🇬🇧
We show that the measured intrinsic octupole moments of $^{220}$ Rn, $^{224}$ Ra, and $^{226}$ Ra constrain the intrinsic Schiff moments of $^{225}$ Ra $^{221}$ Rn, $^{223}$ Rn, $^{223}$ Fr, $^{225}$ Ra, and $^{229}$ Pa. The result is a dramatically reduced uncertainty in intrinsic Schiff moments. Direct measurements of octupole moments in odd nuclei will reduce the uncertainty even more. The only significant source of nuclear-physics error in the laboratory Schiff moments will then be the intrinsic matrix elements of the time-reversal non-invariant interaction produced by CP-violating fundamental physics. Those matrix elements are also correlated with octupole moments, but with a larger systematic uncertainty.
Comments:
5 pages, 3 figures, supplementary material
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.09581 [pdf]
PRL(2018)·81 citations
06
[Submitted on 25 Jul 2018] (cross-list from hep-lat)
Accessing high-momentum nucleons with dilute stochastic sources
J.-J. Wu🇦🇺 · W. Kamleh🇦🇺 · D.~B. Leinweber🇦🇺 · R. D. Young🇦🇺 · J. M. Zanotti🇦🇺
A novel stochastic technique combining a dilute source grid of $Z_{3}$ noise with iterative momentum-smearing is used to study the proton correlation function at rest and in boosted frames on two lattice volumes. The technique makes use of the baryonic version of the so-called one-end trick, and the decomposition into signal and noise terms of the resulting stochastic proton correlation function is made explicit. The number and location of the source points in the dilute grid should be chosen so that the benefits of averaging over many locations overcomes the additional statistical error introduced by the noise terms in the desired fitting region. At all nontrivial momentum values considered we find that the choice of $N = 4$ -- $8$ maximally separated source locations is shown to be optimal, providing a reduced statistical error when compared with a single point source. This enables us to successfully fit the proton energy at momentum values as high as $∣ p ∣ ≃ 3.75$ GeV and $∣ p ∣ ≃ 2.82$ GeV on the small and large volume respectively.
Comments:
13 pages, 12 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1807.09429 [pdf]
J.Phys.G(2018)·13 citations
07
[Submitted on 25 Jul 2018] (cross-list from nucl-th)
Evolution of magnetic fields from the 3+1 dimensional self-similar and Gubser flows in ideal relativistic magnetohydrodynamics
M. Shokri🇮🇷 · N. Sadooghi🇮🇷
Motivated by the recently found realization of the $1 + 1$ dimensional Bjorken flow in ideal and nonideal relativistic magnetohydrodynamics (MHD), we use appropriate symmetry arguments, and determine the evolution of magnetic fields arising from the $3 + 1$ dimensional self-similar and Gubser flows in an infinitely conductive relativistic fluid (ideal MHD). In the case of the $3 + 1$ dimensional self-similar flow, we arrive at a family of solutions, that are related through a differential equation arising from the corresponding Euler equation. To find the magnetic field evolution from the Gubser flow, we solve the MHD equations of a stationary fluid in a conformally flat $d S^{3} \times E^{1}$ spacetime. The results are then Weyl transformed back into the Minkowski spacetime. In this case, the temporal evolution of the resulting magnetic field is shown to exhibit a transition between an early time $1/ t$ decay to a $1/ t^{3}$ decay at a late time. Here, $t$ is the time coordinate. Transverse and longitudinal components of the magnetic fields arising from these flows are also found. The latter turns out to be sensitive to the transverse size of the fluid. In contrast to the result arising from the Gubser flow, the radial domain of validity of the magnetic field arising from the self-similar flow is highly restricted. A comparison of the results suggests that the (conformal) Gubser MHD may give a more appropriate qualitative picture of the magnetic field decay in the plasma of quarks and gluons created in heavy ion collisions.
Comments:
26 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
1807.09487 [pdf]
JHEP(2018)·27 citations
08
[Submitted on 25 Jul 2018] (cross-list from hep-ph)
Convective stability of global thermodynamic equilibrium
Wojciech Florkowski🇵🇱 · Avdhesh Kumar🇵🇱 · Radoslaw Ryblewski🇵🇱
We apply the convection stability criterion to a fluid in global thermodynamic equilibrium with a rigid rotation or with a constant acceleration along the streamlines. Different equations of state describing strongly interacting matter are considered and for each of them the analysed system is found to be stable with respect to convection. This finding brings new evidence for physical relevance of non-static global equilibrium states. Our results can be directly used for other similar media to check their convective stability.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.09526 [pdf]
PRC(2019)·2 citations
09
[Submitted on 24 Jul 2018] (cross-list from hep-ph)
JETSCAPE v1.0 Quickstart Guide
Kolja Kauder (for the JETSCAPE Collaboration)🇺🇸
The JETSCAPE collaboration announced the first public release of its framework and Monte Carlo event generator at this conference, providing a unified interface and a comprehensive suite of model implementations for all stages of ultra-relativistic heavy ion collisions. This release focuses on validation of the framework and the $pp$ reference. A full manual is under development. In the mean-time, these proceedings will provide a guide for installation and simulation runs in lieu of the more traditional summary of the presentation.
Comments:
Proceedings of Quark Matter 2018, submitted to Nuclear Physics A. 4 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.09615 [pdf]
NPA(2019)·23 citations
10
[Submitted on 25 Jul 2018] (cross-list from nucl-ex)
High-resolution hypernuclear spectroscopy at Jefferson Lab, Hall A
Jefferson Lab Hall A Collaboration: F. Garibaldi🇮🇹 · A. Acha🇺🇸 · P. Ambrozewicz🇺🇸 · K.A. Aniol🇺🇸 · P. Beturin🇺🇸 · H. Benaoum🇺🇸 · J. Benesch🇺🇸 · P.Y. Bertin🇫🇷 · K.I. Blomqvist🇩🇪 · W.U. Boeglin🇺🇸 · H. Breuer🇺🇸 · P. Brindza🇺🇸 and 87 other authors
The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in electroproduction on 9Be, 12C and 16O targets. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring-imaging Cherenkov detector were added to the Hall A standard equipment. The high-quality beam, the good spectrometers and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of Lambda 12B. A high-quality Lambda 16N hypernuclear spectrum was likewise obtained. A first measurement of the Lambda binding energy for Lambda 16N, calibrated against the elementary reaction on hydrogen, was obtained with high precision, 13.76 +/- 0.16 MeV. Similarly, the first Lambda 9Li hypernuclear spectrum shows general agreement with theory (distorted-wave impulse approximation with the SLA and BS3 electroproduction models and shell-model wave functions). Some disagreement exists with respect to the relative strength of the states making up the first multiplet. A Lambda separation energy of 8.36 MeV was obtained, in agreement with previous results. It has been shown that the electroproduction of hypernuclei can provide information complementary to that obtained with hadronic probes and the gamma-ray spectroscopy technique.
Comments:
27 pages, 18 figures, submitted to Physical Review C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.09720 [pdf]
PRC(2019)·32 citations
11
[Submitted on 25 Jul 2018] (cross-list from hep-ph)
Radiative quark $p_{T}$ -broadening in a quark-gluon plasma beyond the soft gluon approximation
B.G. Zakharov🇷🇺
We study the radiative correction to $p_{T}$ -broadening of a fast quark in a quark-gluon plasma beyond the soft gluon approximation. We find that the radiative processes can suppress considerably $p_{T}$ -broadening. This differs dramatically from previous calculations to logarithmic accuracy in the soft gluon approximation, predicting a considerable enhancement of $p_{T}$ -broadening.
Comments:
5 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.09742 [pdf]
Pisma Zh.Eksp.Teor.Fiz.(2018)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE