Nuclear Theory·nucl-th

Thursday·July 29, 2021

12 papers—6 primary·6 cross-listed

01
Kaon and pion maximal emission times extraction from the femtoscopy analysis of $5.02 A$ TeV LHC collisions within the integrated hydrokinetic model
V. M. Shapoval🇺🇦 · Yu. M. Sinyukov🇺🇦
A simple method for the extraction of the times of maximal emission for kaons and pions using the combined fitting of their transverse momentum spectra and the longitudinal interferometry radii dependencies on the pair transverse mass $m_{T}$ is applied to Pb+Pb collisions at the LHC energy $s_{N N} = 5.02$ TeV. The method is based on the analytical formulas, that were earlier successfully utilized in the studies of Pb+Pb collisions at $s_{N N} = 2.76$ TeV. To test the method, the spectra, radii and particle radiation picture are calculated within the integrated hydrokinetic model (iHKM), that includes all the stages of the matter evolution in high-energy A+A collisions: the system's formation, its thermalization, viscous hydrodynamics evolution, particlization and subsequent hadronic cascade. The model describes and predicts well already published LHC data in "soft physics? kinematic region. Thus, the fitting results for maximal emission times of kaons and pions are compared to the approximate maximal emission time values, estimated based on the emission function plots, obtained in iHKM. The developed simple method is intended for use in experimental analysis of femtoscopy data in relativistic A+A collisions.
nucl-thhep-phNPA(2021)·7 citations
02
Electromagnetic interaction of low transverse momentum electrons and positrons with heavy nuclei in ultra-peripheral ultra-relativistic heavy-ion collisions
Katarzyna Mazurek🇵🇱 · Mariola Kłusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱
The photon-photon interaction in ultra-relativistic heavy-ion collision is a source of the $(e^{+}, e^{-})$ pairs. The photon-photon fusion leads the lepton creation in the broad configuration space around "collision" point. Those created close to heavy nuclei may undergo strong interaction with them. The impact parameter space distribution of electrons and positrons are calculated within the b-space EPA model of such collisions. The evolution due to the electromagnetic interaction of $(e^{+}, e^{-})$ with nuclei is studied, and the distortion of rapidity and transverse momentum distributions are shown. We show first exploratory results for the reaction Pb+Pb at $s_{N N} =$ 17.3 GeV (SPS) and 200 GeV (RHIC) energies. We provide results for selected creation points and when integrating over their position as dictated by the $b$ -space EPA model. We observe strong effects at low transverse momenta, so far not measured regions of the phase space. In particular, we predict a possible sizeable accumulation of electrons with rapidities close to the beam rapidity. The EM effects lead to asymmetry in the production of electrons and positrons.
nucl-thhep-phEPJA(2022)·5 citations
03
Impact of the leading-order short-range nuclear matrix element on the neutrinoless double-beta decay of medium-mass and heavy nuclei
Lotta Jokiniemi🇪🇸 · Pablo Soriano🇪🇸 · Javier Menéndez🇪🇸
We evaluate the leading-order short-range nuclear matrix element for the neutrinoless double-beta ( $0 ν β β$ ) decay of the nuclei most relevant for experiments, including $^{76}$ Ge, $^{100}$ Mo, $^{130}$ Te and $^{136}$ Xe. In our calculations, performed with the nuclear shell model and proton-neutron quasiparticle random-phase approximation (pnQRPA) methods, we estimate the coupling of this term by the contact charge-independence-breaking coupling of various nuclear Hamiltonians. Our results suggest a significant impact of the short-range matrix element, which is about $15% - 50%$ and $30% - 80%$ of the standard $0 ν β β$ -decay long-range matrix element for the shell model and pnQRPA, respectively. Combining the full matrix elements with the results from current $0 ν β β$ -decay experiments we find that, if both matrix elements carry the same sign, these searches move notably toward probing the inverted mass ordering of neutrino masses.
nucl-thhep-exhep-phnucl-exPLB(2021)·70 citations
04
Charged pion production from Au + Au collisions at $s_{N N} = 2.4$ GeV in the Relativistic Vlasov-Uehling-Uhlenbeck model
Kyle Godbey🇺🇸 · Zhen Zhang🇨🇳 · Jeremy W. Holt🇺🇸 · Che Ming Ko🇺🇸
Using the isospin-dependent relativistic Vlasov-Uehling-Uhlenbeck (RVUU) model, we study charged pion ( $π^{\pm}$ ) production in Au+Au collisions at $s_{N N} =$ 2.4 GeV. By fitting the density dependence of the $Δ$ resonance production cross section in nuclear medium to reproduce the experimental $π^{\pm}$ multiplicities measured by the HADES Collaboration, we obtain a good description of the rapidity distributions and transverse momentum spectra of $π^{\pm}$ in collisions at various centralities. Some shortcomings in the description of $π^{\pm}$ production may indicate the need for including the strong potential on $π^{\pm}$ in RVUU, which is at present absent. We also calculate the proton rapidity distribution in the most central collisions and compare with the coalescence invariant proton rapidity distribution extracted from preliminary HADES data.
nucl-thPLB(2022)·11 citations
05
Self-learning Emulators and Eigenvector Continuation
Avik Sarkar🇺🇸 · Dean Lee🇺🇸
Emulators that can bypass computationally expensive scientific calculations with high accuracy and speed can enable new studies of fundamental science as well as more potential applications. In this work we discuss solving a system of constraint equations efficiently using a self-learning emulator. A self-learning emulator is an active learning protocol that can be used with any emulator that faithfully reproduces the exact solution at selected training points. The key ingredient is a fast estimate of the emulator error that becomes progressively more accurate as the emulator is improved, and the accuracy of the error estimate can be corrected using machine learning. We illustrate with three examples. The first uses cubic spline interpolation to find the solution of a transcendental equation with variable coefficients. The second example compares a spline emulator and a reduced basis method emulator to find solutions of a parameterized differential equation. The third example uses eigenvector continuation to find the eigenvectors and eigenvalues of a large Hamiltonian matrix that depends on several control parameters.
nucl-thcs.LGcs.NAhep-lat+1PRResearch(2022)·33 citations
06
Estimating Microscopic Nuclear Data by Compact Star Observations
Balázs Endre Szigeti🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Péter Pósfay🇭🇺 · Antal Jakovác🇭🇺
We studied recent observation data of pulsar masses and radii of PSR J0740 $+$ 6620, PSR J0348 $+$ 0432, and PSR J1614 $-$ 2230 from different measurements, based on the extended version of $σ$ - $ω$ model. Throughout our analysis, we assumed that these pulsars are maximal-mass compact stars, thus we applied the core approximation. Based on the linear relation between the microscopic and macroscopic parameters of compact stars evaluated by our model, we estimated the average Landau mass $m_{L} = 752.4 6_{- 42.5}^{+ 49.1}$ MeV and compressibility $K = 261. 7_{- 28.0}^{+ 57.2}$ MeV.
nucl-thastro-ph.HEhep-phEPJ Web Conf.(2022)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Kaon and pion maximal emission times extraction from the femtoscopy analysis of 5.02A TeV LHC collisions within the integrated hydrokinetic model

Electromagnetic interaction of low transverse momentum electrons and positrons with heavy nuclei in ultra-peripheral ultra-relativistic heavy-ion collisions

Impact of the leading-order short-range nuclear matrix element on the neutrinoless double-beta decay of medium-mass and heavy nuclei

Charged pion production from Au + Au collisions at sNN​​=2.4 GeV in the Relativistic Vlasov-Uehling-Uhlenbeck model

Self-learning Emulators and Eigenvector Continuation

Estimating Microscopic Nuclear Data by Compact Star Observations

Affiliations

Kaon and pion maximal emission times extraction from the femtoscopy analysis of $5.02 A$ TeV LHC collisions within the integrated hydrokinetic model

Charged pion production from Au + Au collisions at $s_{N N} = 2.4$ GeV in the Relativistic Vlasov-Uehling-Uhlenbeck model