Nuclear Theory·nucl-th

Friday·December 20, 2019

16 papers—6 primary·10 cross-listed

01
[Submitted on 19 Dec 2019]
Microscopic calculations of nuclear level densities with the Lanczos method
W. E. Ormand · B. A. Brown
A new method for computing the density of states in nuclei making use of an extrapolated form of the tri-diagonal matrix obtained from the Lanczos method is presented. It will be shown that the global, average properties of the entire Lanczos matrix can be predicted from just four Lanczos iterations. The extrapolated Lanczos matrix (ELM) approach provides for an accurate computation of the density of states described within the configuration space, which, in some cases, is sufficient to accurately calculate the density of states at, or near, the neutron separation energy. Comparisons between theory and experiment are shown for $^{57}$ Fe, $^{74}$ Ge, and $^{76}$ Ge. In addition, we show results for the $J$ -dependence of moments and the level density for these three nuclei.
Comments:
19 pages, 23 figures, 5 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.08973 [pdf]
PRC(2020)·30 citations
02
[Submitted on 19 Dec 2019]
Systematical study of optical potential strengths in reactions involving strongly, weakly bound and exotic nuclei on $^{120}$ Sn
M. A. G. Alvarez · J. P. Fernández-Garcíaa · J. L. León-García · M. Rodríguez-Gallardo · L. R. Gasques · L. C. Chamon · V. A. B. Zagatto · A. Lépine-Szily · J. R. B. Oliveira · V. Scarduelli · B. V. Carlson · J. Casal and 3 other authors
We present new experimental angular distributions for the elastic scattering of $^{6}$ Li $+^{120}$ Sn at three bombarding energies. We include these data in a wide systematic involving the elastic scattering of $^{4, 6}$ He, $^{7}$ Li, $^{9}$ Be, $^{10}$ B and $^{16, 18}$ O projectiles on the same target at energies around the respective Coulomb barriers. Considering this data set, we report on optical model analyses based on the double-folding Sao Paulo Potential. Within this approach, we study the sensitivity of the data fit to different models for the nuclear matter densities and to variations in the optical potential strengths.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.09130 [pdf]
PRC(2019)·20 citations
03
[Submitted on 18 Dec 2019]
Monte-Carlo generator of heavy ion collisions DCM-SMM
M. Baznat🇲🇩 · A. Botvina🇷🇺 · G. Musulmanbekov🇷🇺 · V. Toneev🇷🇺 · V. Zhezher🇷🇺
The new monte-carlo generator of heavy ion collisions, DCM-SMM, based on Dubna Cascade Model (DCM-QGSM) and Statistical Multifragmentation Model (SMM) is described. The model aimed to generate particle--nucleus and nucleus--nucleus collisions at a wide range of energy was created to provide the computer simulation support to new experimental facilities BMN and MPD at the accelerator complex NICA. It can simulate the production of both light particles and nuclear fragments and hyperfragments on the event by event basis.
Comments:
33 pages, 16 figures. arXiv admin note: text overlap with arXiv:0806.3455
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
1912.09277 [pdf]
Phys.Part.Nucl.Lett.(2020)·85 citations
04
[Submitted on 19 Dec 2019]
Nuclear and neutron-star matter from local chiral interactions
D. Lonardoni🇺🇸 · I. Tews🇺🇸 · S. Gandolfi🇺🇸 · J. Carlson🇺🇸
We report a quantum Monte Carlo calculation of the equation of state of symmetric nuclear matter using local interactions derived from chiral effective field theory up to next-to-next-to-leading order fit to few-body observables only. The empirical saturation density and energy are well reproduced within statistical and systematic uncertainties. We have also derived the symmetry energy as a function of the density, finding good agreement with available experimentally derived constraints at saturation and twice saturation density. We find that the corresponding pressure is also in excellent agreement with recent constraints extracted from gravitational waves of the neutron-star merger GW170817 by the LIGO-Virgo detection.
Comments:
7 pages, 3 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
1912.09411 [pdf]
PRResearch(2020)·106 citations
05
[Submitted on 19 Dec 2019]
Microscopic Optical Potential for Elastic Proton-Nucleus Scattering from Chiral Forces
C. Giusti · M. Vorabbi · P. Finelli
A microscopic optical potential (OP) is derived from NN chiral potentials at the first-order term within the spectator expansion of the multiple scattering theory and adopting the impulse approximation. The performances of our OP are compared with those of a phenomenological OP in the description of elastic proton scattering data on different isotopic chains. An analogous scheme is adopted to construct a microscopic OP for elastic antiproton-nucleus scattering. The results of our OPs are in reasonably good agreement with the experimental data, for both elastic proton and antiproton-nucleus scattering.
Comments:
10 pages, 4 figure, Proceedings of the 38th International Workshop in Nuclear Theory, IWNT-2019, Rila Mountains, Bulgaria
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.09415 [pdf]
Nucl.Theor.(2019)·0 citations
06
[Submitted on 19 Dec 2019]
A schematic reaction-theory model for nuclear fission
G. F. Bertsch
The K-matrix formalism is applied to a schematic model for nuclear fission. The purpose is to explore the dependence of observables on the assumptions made about the configuration space and nucleon interaction in the Hamiltonian of the fissile nucleus. As expected, branching ratios in induced fission are found to depend sensitively on the character of the residual interaction, whether it is pairing in form or taken from a random ensemble. On the other hand, the branching ratio is not much affected by the presence of additional configurations that do not introduce new fission paths.
Comments:
6 pages 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.09469 [pdf]
PRC(2020)·10 citations
07
[Submitted on 18 Dec 2019] (cross-list from hep-th)
Drag force to all orders in gradients
Jared Reiten🇺🇸 · Andrey V. Sadofyev🇺🇸
We study the energy loss of a heavy quark slowly moving through an evolving strongly coupled plasma. We use the linearized fluid/gravity correspondence to describe small perturbations of the medium flow with general spacetime dependence. This all order linearized hydrodynamics results in a drag force exerted on a heavy quark even when it is at rest with the fluid element. We show how the general contribution to the drag force can be derived order by order in the medium velocity gradients and provide explicit results valid up to the third order. We then obtain an approximate semi-analytic result for the drag force to all orders in the gradient expansion but linearized in the medium velocity. Thus, the effects of a class of hydrodynamic gradients on the drag force are re-summed, giving further insight into the dissipative properties of strongly coupled plasmas. The all order result allows us to study the drag force in the non-hydrodynamic regime of linear medium perturbations that vary rapidly in space and time.
Comments:
25 pages, 4 figures. v2: Journal version, references and figure added
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1912.08816 [pdf]
JHEP(2020)·23 citations
08
[Submitted on 18 Dec 2019] (cross-list from hep-ph)
Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly
Antonio M. Coutinho🇨🇭 · Andreas Crivellin🇨🇭 · Claudio Andrea Manzari🇨🇭
Recently, discrepancies of up to $4 σ$ between the different determinations of the Cabibbo angle were observed. This "Cabibbo-angle anomaly" could be explained by lepton flavour universality (LFU) violating New Physics (NP) in the neutrino sector. However, modified neutrino couplings to Standard Model gauge bosons also affect many other observables sensitive to LFU violation which have to be taken into account in order to assess the viability of this explanation. Therefore, we perform a model-independent global analysis in a Bayesian approach and find that the tension in the Cabibbo angle is significantly reduced, while the agreement with other data is also mostly improved. In fact, non-zero modifications of electron and muon neutrino couplings are preferred at more than 99\% CL. Still, since constructive effects in the muon sector are necessary, simple models with right-handed neutrinos (whose global fit we update as a by-product) cannot fully explain data, pointing towards more sophisticated NP models.
Comments:
10 pages, 3 figures and 4 tables; journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1912.08823 [pdf]
PRL(2020)·135 citations
09
[Submitted on 18 Dec 2019] (cross-list from hep-ph)
Rapidity loss, spin and angular asymmetries in scattering of a quark from color field of a proton (nucleus)
Jamal Jalilian-Marian🇺🇸
We calculate the helicity amplitudes for scattering of a quark from both large and small $x$ gluons of a target proton or nucleus using spinor helicity formalism. We show that scattering from large $x$ gluons of the target results in non-zero spin asymmetry at intermediate $p_{t}$ as well as rapidity loss of the projectile quark. We comment on how this can also generate angular asymmetries in particle production in high energy collisions.
Comments:
11 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1912.08878 [pdf]
PRD(2020)·51 citations
10
[Submitted on 18 Dec 2019] (cross-list from hep-ph)
The Frame-Independent Spatial Coordinate $z ~$ : Implications for Light-Front Wave Functions, Deep Inelastic Scattering, Light-Front Holography, and Lattice QCD Calculations
Gerald A. Miller🇺🇸 · Stanley J. Brodsky🇺🇸
A general procedure for obtaining frame-independent, three-dimensional light-front coordinate-space wave functions is introduced. The third spatial coordinate, $z ~$ , is the frame independent coordinate conjugate to the light-front momentum coordinate $x = \frac{k ^{+}}{P ^{+}}$ which appears in the momentum-space light-front wave functions underlying generalized parton distributions, structure functions, distribution amplitudes, form factors, and other hadronic observables. These causal light-front coordinate-space wave functions are used to derive a general expression for the quark distribution function of hadrons as an integral over the frame-independent longitudinal distance (the Ioffe time) between virtual-photon absorption and emission appearing in the forward virtual photon-hadron Compton scattering amplitude. Specific examples using models derived from light-front holographic QCD show that the spatial extent of the proton eigenfunction in the longitudinal direction can have very large extent in $z ~$ .
Comments:
6 pages, 6 figures, this version adds references, corrects a typographical error and contains more explanations regarding the use of the variable $z ~$
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1912.08911 [pdf]
PRC(2020)·38 citations
11
[Submitted on 19 Dec 2019] (cross-list from hep-ph)
Quark/hadronic matter and dualities of QCD thermodynamics
T. G. Khunjua🇷🇺 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺
In this letter the dualities of thermodynamics of dense quark/hadronic matter are discussed. It is shown that chiral symmetry breaking (CSB) phenomenon is dual to charged pion condensation (PC) phenomenon.
Comments:
Talk presented at the 19th Lomonosov Conference on Elementary Particle Physics, Moscow State University, Moscow, Russia, from 22 to 28 of August, 2019
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1912.09102 [pdf]
1 citation
12
[Submitted on 19 Dec 2019] (cross-list from hep-ph)
Diffusion processes involving multiple conserved charges: a first study from kinetic theory and implications to the fluid-dynamical modeling of heavy ion collisions
Jan A. Fotakis🇩🇪 · Moritz Greif🇩🇪 · Gabriel Denicol🇩🇪 · Harri Niemi🇧🇷 · Carsten Greiner🇫🇮
The bulk nuclear matter produced in heavy ion collisions carries a multitude of conserved quantum numbers: electric charge, baryon number, and strangeness. Therefore, the diffusion processes associated to these conserved charges cannot occur independently and must be described in terms of a set of coupled diffusion equations. This physics is implemented by replacing the traditional diffusion coefficients for each conserved charge by a diffusion coefficient matrix, which quantifies the coupling between the conserved quantum numbers. The diagonal coefficients of this matrix are the usual charge diffusion coefficients, while the off-diagonal entries describe the diffusive coupling of the charge currents. In this paper, we show how to calculate this diffusion coefficient matrix from kinetic theory and provide results for a hadron resonance gas and a gas of partons. We further find that the off-diagonal entries can reach similar magnitudes compared to the diagonal entries. In order to provide some insight on the influence that the coupling between the net charge diffusion currents can have on heavy ion observables, we present first results for the diffusive evolution of a hadronic system in a simple (1+1)D-fluid dynamics approach, and study different configurations of the diffusion matrix.
Comments:
27 pages, 10 Figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1912.09103 [pdf]
PRD(2020)·70 citations
13
[Submitted on 19 Dec 2019] (cross-list from hep-ph)
Basic properties of GPDs and modelling of the latter
Cédric Mezrag🇫🇷 · Nabil Chouika🇫🇷 · Hervé Moutarde🇫🇷 · Jose Rodriguez-Quintero🇪🇸
We present here a new method based on the Radon transform to model Generalised Parton Distributions (GPDs). It allows to fulfil all theoretical constraints applying on GPDs, especially polynomiality and positivity at the same time. More specifically, we show how polynomiality can be systematically restored within the framework of the overlaps of Lightfront Wave Functions (LFWFs). It provides a systematic way to extend models defined solely in the DGLAP kinematical region to the ERBL one. We then exemplify our approach using LFWFs models.
Comments:
Contribution to the proceedings of Lightcone 2019, École Polytechnique, Palaiseau, France
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1912.09106 [pdf]
PoS(2019)·0 citations
14
[Submitted on 19 Dec 2019] (cross-list from nucl-ex)
Survey of deformation in nuclei in order to estimate the enhancement of sensitivity to atomic EDM
Prajwal Mohanmurthy · Umesh Silwal · Durga P. Siwakoti · Jeff A. Winger
The observed baryon asymmetry of the universe (BAU) cannot be explained by the known sources of charge-parity (CP)-violation in the Standard Model (SM). A non-zero permanent electric-dipole-moment (EDM) for fundamental particles, nuclei or atoms, violates CP. Measuring a non-zero EDM allows us to gain a handle on additional sources of CP-violation required to explain the observed BAU. The EDM of an atom with an octupole and quadrupole deformed nucleus is enhanced. Therefore, the search for such atoms has become important in the quest to measure an EDM. Viability of EDM searches in $^{225}$ Ra atoms with a deformed nucleus have already been demonstrated. We have performed a comprehensive survey for possible EDM candidates from a list of octupole deformed nuclei predicted by various theoretical models. Our search of long-lived isotopes with nuclear deformations comparable to or better than $^{225}$ Ra results in a handful of viable candidates for future atomic EDM experiments based out of the Facility for Rare Isotope Beams (FRIB): $^{221}$ Rn, $^{221, 223, 227}$ Fr, $^{221, 223, 225}$ Ra, $^{223, 225, 227}$ Ac, $^{229}$ Th, and particularly $^{229}$ Pa. Furthermore, nuclei of $^{223, 225}$ Rn, $^{225}$ Fr and $^{226}$ Ac are also highly quadrupole and octupole deformed, but their ground state parity doublet energy difference has not yet been measured.
Comments:
Proceedings of The 15th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon, MENU-2019; Jun 2-7, 2019, Carnegie Mellon University, Pittsburgh, PA; Abs. ID: 98. 7 Pages, 3 Tables
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1912.09271 [pdf]
AIP Conf.Proc.(2020)·6 citations
15
[Submitted on 19 Dec 2019] (cross-list from gr-qc)
Postmerger Gravitational-Wave Signatures of Phase Transitions in Binary Mergers
Lukas R. Weih🇩🇪 · Matthias Hanauske🇩🇪 · Luciano Rezzolla🇩🇪
With the first detection of gravitational waves from a binary system of neutron stars, GW170817, a new window was opened to study the properties of matter at and above nuclear-saturation density. Reaching densities a few times that of nuclear matter and temperatures up to $100 MeV$ , such mergers also represent potential sites for a phase transition (PT) from confined hadronic matter to deconfined quark matter. While the lack of a postmerger signal in GW170817 has prevented us from assessing experimentally this scenario, two theoretical studies have explored the postmerger gravitational-wave signatures of PTs in mergers of binary systems of neutron stars. We here extend and complete the picture by presenting a novel signature of the occurrence of a PT. More specifically, using fully general-relativistic hydrodynamic simulations and employing a suitably constructed equation of state that includes a PT, we present the occurrence of a "delayed PT", i.e. a PT that develops only some time after the merger and produces a metastable object with a quark-matter core, i.e. a hypermassive hybrid star. Because in this scenario, the postmerger signal exhibits two distinct fundamental gravitational-wave frequencies -- before and after the PT -- the associated signature promises to be the strongest and cleanest among those considered so far, and one of the best signatures of the production of quark matter in the present Universe.
Comments:
6 pages, 4 figures, includes supplemental material, matches version accepted to PRL
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1912.09340 [pdf]
PRL(2020)·211 citations
16
[Submitted on 19 Dec 2019] (cross-list from hep-ph)
Heavy-light flavour correlations of anisotropic flows at LHC energies within event-by-event transport approach
Salvatore Plumari🇮🇹 · Gabriele Coci🇮🇹 · Vincenzo Minissale🇮🇹 · Santosh K. Das🇮🇳 · Yifeng Sun🇮🇹 · Vincenzo Greco🇮🇹
The heavy quarks (HQs) are unique probe of the hot QCD matter properties and their dynamics is coupled to the locally thermalized expanding quark gluon plasma. We present here a novel study of the event by event correlations between light and heavy flavour flow harmonics at LHC energy within a transport approach. Interaction between heavy quarks and light quarks have been taken into account exploring the impact of different temperature dependence of the transport coefficients $D_{s}$ and $Γ$ . Our study indicates that $v_{n}^{h e a v y} - v_{n}^{l i g h t}$ correlation and the relative fluctuations of anisotropic flows, $σ_{v_{n}} / ⟨ v_{n} ⟩$ , are novel observables to understand the heavy quark-bulk interaction and are sensitive to the temperature dependence even to moderate differences of $D_{s} (T)$ , or $Γ (T)$ . Hence a comparison of such new observables for HQ to upcoming experimental data at both RHIC and LHC can put further constraints on heavy quark transport coefficients and in particular on its temperature dependence toward a solid comparison between the phenomenological determination and the lattice QCD calculations.
Comments:
7 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1912.09350 [pdf]
PLB(2020)·60 citations

Affiliations

first authorsco-authorsvia INSPIRE