Nuclear Experiment·nucl-ex
8 papers—1 primary·7 cross-listed·reconstructed*
An objection is presented to the original paper authors' assumption, that the GDR Lorentzian parametrization can be extended to energies as low as 1 MeV. Consequently, totally destructive interference is not possible between the three components of the elastic photon scattering (T, R, and GDR) paving the way for a very clean Delbruck scattering.
Antonio Carlos Oliveira da Silva (for the ALICE Collaboration)🇺🇸
The comparison of experimental data and theoretical predictions is important for our understanding of the mechanisms for interactions and particle production in hadron collisions, both at the Large Hadron Collider and at the Relativistic Heavy-Ion Collider experiments. Several tools were ideated to help with that. Rivet (Robust Independent Validation of Experiment and Theory) is a framework that facilitates the comparison between measurements from high-energy physics experiments and Monte Carlo event generators able to produce outputs using the HepMC package. Rivet contains a repository with analysis algorithms developed by experiments, providing analysis documentation and preservation. The recent development of features for the implementation of heavy-ion collision analyses, such as centrality determination, will be presented in this contribution, together with some of the open points still to be addressed.
F. R. Xu🇨🇳
A short discussion on possible multineutron resonances.
C. V. Sukumar · A. Bonaccorso🇮🇹
David Brink was one of the leading theoretical nuclear physicists of his generation. He made major contributions to the study of all aspects of nuclear physics embracing nuclear structure, nuclear scattering, and nuclear instability. His wide ranging interests and interactions with theorists and experimentalists alike helped him in providing both theoretical analysis and interpretations and suggesting experiments. He had the gift of visualising complex problems in simple terms and provided clear analysis of the underlying processes. He was an expert on the use of semi-classical methods which provided an intuitively clear picture of complex phenomena. His research work and books are characterised by scientific clarity, transparency, and depth. David possessed outstanding skills in mathematical computation, and he was an expert on special functions, group theory, and the Feynman path integral method. David had many research students and collaborated with a large number of scientists from across the world, for whom he was a source of scientific and human inspiration and admiration. His most fundamental belief was that research was a means of trying to discover and understand the beauties of Nature and explain them in simple terms to others. His absolute belief in the value of truth and his unselfish and generous attitude in sharing knowledge makes him an outstanding figure in contemporary Nuclear Physics.
Ze-Fang Jiang🇨🇳 · Xiang-Yu Wu🇨🇳 · Shanshan Cao🇨🇳 · Ben-Wei Zhang🇨🇳
We study the directed flow of identified particles in Au+Au collisions at to 62.4 GeV. The Glauber model is extended to include both a tilted deformation of the QGP fireball with respect to the longitudinal direction and a non-zero longitudinal flow velocity gradient in the initial state. By combining this improved initial condition with a (3+1)-dimensional viscous hydrodynamic model calculation, we obtain a satisfactory description of the transverse momentum spectra and the rapidity dependent directed flow coefficient of different hadron species. Our calculation indicates the sensitivity of the hadron directed flow, especially its splitting between protons and antiprotons, to both the initial geometry and the initial longitudinal flow velocity. Therefore, the combination of directed flow of different hadrons can provide a tight constraint on the initial condition of nuclear matter created in heavy-ion collisions. The initial condition extracted from the directed flow is further tested with the global polarization of and within the same theoretical framework, where we obtain a reasonable description of these hyperon polarization observed at different collision energies at RHIC.
Yangyang Liu🇨🇳 · Yingxun Zhang🇨🇳 · Junping Yang🇨🇳 · Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳 · Zhuxia Li🇨🇳
Based on the ultra-relativistic quantum molecular dynamics (UrQMD) model, the impacts of momentum dependent interaction, symmetry energy and near-threshold cross sections on isospin sensitive collective flow and pion observables are investigated. Our results confirm that the elliptic flow of neutrons and charged particles, i.e. and , are sensitive to the strength of momentum dependence interaction and the elliptic flow ratio, i.e., , is sensitive to the stiffness of symmetry energy. For describing the pion multiplicity near the threshold energy, accurate cross sections are crucial. With the updated momentum dependent interaction and cross sections in UrQMD model, seven observables, such as directed flow and elliptic flow of neutrons and charged particles, the elliptic flow ratio of neutrons to charged particles, charged pion multiplicity and its ratio , can be well described by the parameter sets with the slope of symmetry energy from 5 MeV to 70 MeV. To describe the constraints of symmetry energy at the densities probed by the collective flow and pion observables, the named characteristic density is investigated and used. Our analysis found that the flow characteristic density is around 1.2 and pion characteristic density is around 1.5, and we got the constrains of symmetry energy at characteristic densities are MeV and MeV. These results are consistent with previous analysis by using pion and flow observable with different transport models, and demonstrate a reasonable description of symmetry energy constraint should be presented at the characteristic density of isospin sensitive observables.
Tanmoy Bhattacharya🇺🇸 · Rajan Gupta🇺🇸 · Kate Scholberg🇺🇸
The aim of this white paper is to highlight several areas for which the Department of Energy's Office of Nuclear Physics has primary stewardship or significant investment and expertise, and for which there is also significant interest and expertise within the HEP community. These areas of overlap offer exciting opportunities for collaboration.
Aman Dimri🇺🇸 · Somadutta Bhatta🇺🇸 · Jiangyong Jia🇺🇸
The shape of atomic nuclei is often interpreted to possess a quadrupole deformation that fluctuates around some average profile. We investigate the impact of nuclear shape fluctuations on the initial state geometry in heavy ion collisions, particularly its eccentricity and inverse size , which can be related to the elliptic and radial flow in the final state. The fluctuation in overall quadrupole deformation enhances the variances and modifies the skewness and kurtosis of the and in a controllable manner. The fluctuation in triaxiality reduces the difference between prolate and oblate shape for any observable, whose values, in the large fluctuation limit, approach those obtained in collisions of rigid triaxial nuclei. The method to disentangle the mean and variance of the quadrupole deformation is discussed.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.