Nuclear Theory·nucl-th

Thursday·October 18, 2018

10 papers—5 primary·5 cross-listed

01
Partial correlation analysis in ultra-relativistic nuclear collisions
Wojciech Broniowski🇵🇱 · Adam Olszewski🇵🇱
We show that the method of partial covariance is a very efficient way to introduce constraints (such as the centrality selection) in data analysis in ultra-relativistic nuclear collisions. The technique eliminates spurious event-by-event fluctuations of physical quantities due to fluctuations of control variables. Moreover, in the commonly used superposition approach to particle production the method can be used to impose constraints on the initial sources rather than on the finally produced particles, thus separating out the trivial fluctuations from statistical hadronization or emission from sources and focusing strictly on the initial-state physics. As illustration, we use simulated data from hydrodynamics started on the wounded-quark event-by-event initial conditions, followed with statistical hadronization, to show the practicality of the approach in analyzing the forward-backward multiplicity fluctuations. We mention generalizations to the case with several constraints and other observables, such as the transverse momentum or eccentricity correlations.
nucl-thnucl-ex0 citations
02
3H and 3He calculations without angular momentum decomposition
K. Topolnicki🇵🇱
Results for the three nucleon (3N) bound state carried out using the "three dimensional" (3D) formalism are presented. In this approach calculations are performed without the use of angular momentum decomposition and instead rely directly on the 3D degrees of freedom of the nucleons. In this paper, for the first time, 3D results for $^{3}$ He bound state with the inclusion of the screened Coulomb potential are compared to $^{3}$ H calculations. Additionally, using these results, matrix elements of simple current operators related to the description of beta decay of the triton are given. All computations are carried out using the first generation of NNLO two nucleon (2N) and 3N forces from the Bochum - Bonn group.
nucl-thPRC(2019)·1 citation
03
Gogny forces in the astrophysical context
X. Viñas🇪🇸 · C. Gonzalez-Boquera🇪🇸 · M. Centelles🇪🇸 · L.M. Robledo🇪🇸 · C. Mondal🇪🇸
The most successful Gogny interactions of the D1 family, namely D1S, D1N and D1M, suffer the common problem of a too soft neutron matter equation of state at high density, which prevents them from predicting a maximal mass of neutron stars of two solar masses, as required by recent astronomical observations. To cure this deficiency, we have proposed recently a reparametrization of the D1M force by fine tuning the slope of the symmetry energy in such a way that it preserves the ground-state properties of D1M in finite nuclei and also describes successfully the global properties of neutron stars, in particular its maximal mass, in consonance with the observational data. In this contribution we revisit this reparametrization by discussing two modified Gogny forces, dubbed D1M $^{*}$ and D1M $^{**}$ .
nucl-thNucl.Theor.(2018)·6 citations
04
The pressure distribution and shear forces inside the proton
P. E. Shanahan🇺🇸 · W. Detmold🇺🇸
The distributions of pressure and shear forces inside the proton are investigated using lattice Quantum Chromodynamics (LQCD) calculations of the energy momentum tensor, allowing the first model-independent determination of these fundamental aspects of proton structure. This is achieved by combining recent LQCD results for the gluon contributions to the energy momentum tensor with earlier calculations of the quark contributions. The utility of LQCD calculations in exploring, and supplementing, the assumptions in a recent extraction of the pressure distribution in the proton from deeply virtual Compton scattering experiments is also discussed. Based on this study, the target kinematics for experiments aiming to determine the pressure and shear distributions with greater precision at Thomas Jefferson National Accelerator Facility and a future Electron Ion Collider are investigated.
nucl-thhep-lathep-phPRL(2019)·154 citations
05
Neutrino-nucleus cross section within the extended factorization scheme
Noemi Rocco🇬🇧 · Carlo Barbieri🇬🇧 · Omar Benhar🇮🇹 · Arturo De Pace🇮🇹 · Alessandro Lovato🇺🇸
The factorization scheme, based on the impulse approximation and the spectral function formalism, has been recently generalized to allow the description of electromagnetic nuclear interactions driven by two-nucleon currents. We have extended this framework to the case of weak charged and neutral currents and carried out calculations of the double-differential neutrino-carbon and neutrino-oxygen cross sections using two different models of the target spectral functions. The results, showing a moderate dependence on the input spectral function, confirm that our approach provides a consistent treatment of all reaction mechanisms contributing to the signals detected by accelerator-based neutrino experiments.
nucl-thhep-exPRC(2019)·74 citations
06
Nonextensive quasiparticle description of QCD matter
Jacek Rożynek🇵🇱 · Grzegorz Wilk🇵🇱
The dynamics of QCD matter is often described using effective mean field (MF) models based on Boltzmann-Gibbs (BG) extensive statistics. However, such matter is normally produced in small packets and in violent collisions where the usual conditions justifying the use of BG statistics are not fulfilled and the systems produced are not extensive. This can be accounted for either by enriching the original dynamics or by replacing the BG statistics by its nonextensive counterpart described by a nonextensivity parameter $q \neq = 1$ (for $q \to 1$ one returns to the extensive situation). In this work we investigate the interplay between the effects of dynamics and nonextensivity. Since the complexity of the nonextensive MF models prevents their simple visualization, we instead use some simple quasi-particle description of QCD matter in which the interaction is modelled phenomenologically by some effective fugacities, $z$ . Embedding such a model in a nonextensive environment allows for a well-defined separation of the dynamics (represented by $z$ ) and the nonextensivity (represented by $q$ ) and a better understanding of their relationship.
↳ hep-phnucl-thSymmetry(2019)·9 citations
07
High-energy neutrino-nucleus interactions
S. Kumano🇯🇵
High-energy neutrino-nucleus interactions are discussed by considering neutrino-oscillation experiments and ultra-high-energy cosmic neutrino interactions. The largest systematic error for the current neutrino oscillation measurements comes from the neutrino-nucleus interaction part, and its accurate understanding is essential for high-precision neutrino physics, namely for studying CP violation in the lepton sector. Depending on neutrino beam energies, quasi-elastic, resonance, Regge, or/and deep inelastic scattering (DIS) processes contribute to the neutrino cross section. It is desirable to have a code to calculate the neutrino-nucleus cross section in any kinematical range by combining various theoretical descriptions. On the other hand, the IceCube collaboration started obtaining cross section data up to the $1 0^{15}$ eV range, so that it became necessary to understand ultra-high-energy neutrino interactions beyond the artificial lepton-accelerator energy range. For future precise neutrino physics including the CP measurement, it is also necessary to understand accurate nuclear corrections. The current status is explained for nuclear corrections in DIS structure functions. The possibility is also discussed to find gravitational sources within nucleons and nuclei, namely matrix elements of quark-gluon energy-momentum tensor. They could be probed by neutrino interactions without replying on direct ultra-weak "gravitational interactions" with high-intensity neutrino beams, possibly at a future neutrino factory, by using techniques of hadron tomography.
↳ hep-phhep-exnucl-exnucl-thEPJ Web Conf.(2019)·2 citations
08
Resonances in the solar neutrino capture cross-section for $^{76} G e$ nuclei
A.N. Fazliakhmetov🇷🇺 · L.V. Inzhechik🇷🇺 · G.A. Koroteev🇷🇺 · Yu.S. Lutostanky🇷🇺 · V.N. Tikhonov🇷🇺 · A.K. Vyborov🇷🇺
The calculation results of solar neutrino capture cross-section on the $^{76} G e$ nucleus are presented. The charge-exchange strength function $S (E)$ was obtained from the experiment data in the $^{76} G e (^{3} H e, t)^{76} A s$ reaction. The calculation includes the effect of the resonant structure of the strength function $S (E)$ on the calculated cross section $σ (E_{ν})$ . It is shown that only the giant Gamow-Teller resonance contributes about 20%, and an even greater contribution is made by excited states located lower in the continuous part of the spectrum. These contributions should be taken into account in the calculation of background events in experiments on double beta decay of the GERDA type (for example LEGEND).
↳ nucl-exnucl-th0 citations
09
DIS at small x and hadron-hadron scattering at high energies via the holographic Pomeron exchange
Akira Watanabe🇨🇳
We present our analysis on the high energy scattering processes in the framework of the holographic QCD, assuming that the Pomeron exchange gives a dominant contribution to the cross sections. Focusing on the two-body scattering, we employ the Brower-Polchinski-Strassler-Tan Pomeron exchange kernel to describe the strong gluonic interaction, and utilize the bottom-up AdS/QCD models to obtain the density distributions of the involved hadrons in the five-dimensional AdS space, to calculate the total cross sections. Considering the unpolarized deep inelastic scattering at small Bjorken $x$ and the high energy hadron-hadron scattering, we show that our calculations are consistent with the presently available experimental data. Our predictions made via this framework can be tested at various experimental facilities in the future.
↳ hep-phnucl-thPhys.Part.Nucl.Lett.(2019)·2 citations
10
Non-congruent phase transitions in strongly interacting matter within the Quantum van der Waals model
Roman Poberezhnyuk🇺🇦 · Volodymyr Vovchenko🇩🇪 · Mark I. Gorenstein🇺🇦 · Horst Stoecker🇩🇪
The non-congruent liquid-gas phase transition (LGPT) in asymmetric nuclear matter is studied using the recently developed Quantum van der Waals model in the grand canonical ensemble. Different values of the electric-to-baryon charge ratio, $Q / B$ , are considered. This non-congruent LGPT exhibits several features which are not present in the congruent LGPT of symmetric nuclear matter. These include a continuous phase transformation, a change in the location of the critical point, and the separation of the critical point and the endpoints. The effects which are associated with the non-congruent LGPT become negligible for the following cases: when $Q / B$ approaches its limiting values, $0.5$ or $0$ , or if quantum statistical effects can be neglected. The latter situation is realized when the particle degeneracy attains large values, $g ≳ 10$ .
↳ hep-phnucl-thPRC(2019)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE