We present results for pseudo-critical temperatures of QCD chiral crossovers at zero and non-zero values of baryon (B), strangeness (S), electric charge (Q), and isospin (I) chemical potentials ...μX=B,Q,S,I. The results were obtained using lattice QCD calculations carried out with two degenerate up and down dynamical quarks and a dynamical strange quark, with quark masses corresponding to physical values of pion and kaon masses in the continuum limit. By parameterizing pseudo-critical temperatures as Tc(μX)=Tc(0)1−κ2X(μX/Tc(0))2−κ4X(μX/Tc(0))4, we determined κ2X and κ4X from Taylor expansions of chiral observables in μX. We obtained a precise result for Tc(0)=(156.5±1.5) MeV. For analogous thermal conditions at the chemical freeze-out of relativistic heavy-ion collisions, i.e., μS(T,μB) and μQ(T,μB) fixed from strangeness-neutrality and isospin-imbalance, we found κ2B=0.012(4) and κ4B=0.000(4). For μB≲300 MeV, the chemical freeze-out takes place in the vicinity of the QCD phase boundary, which coincides with the lines of constant energy density of 0.42(6)GeV/fm3 and constant entropy density of 3.7(5)fm−3.
What is the size of the atomic nucleus? This deceivably simple question is dicult to answer. Although the electric charge distributions in atomic nuclei were measured accurately already half a ...century ago, our knowledge of the distribution of neutrons is still decient. In addition to constraining the size of atomic nuclei, the neutron distribution also impacts the number of nuclei that can exist and the size of neutron stars. We present an ab initio calculation of the neutron distribution of the neutron-rich nucleus 48Ca. We show that the neutron skin (dierence between the radii of the neutron and proton distributions) is signicantly smaller than previously thought. We also make predictions for the electric dipole polarizability and the weak form factor; both quantities that are at present targeted by precision measurements. Based on ab initio results for 48Ca, we provide a constraint on the size of a neutron star.
I have been teaching courses on experimental techniques in nuclear and particle physics to master students in physics and in engineering for many years. This book grew out of the lecture notes I made ...for these students. The physics and engineering students have rather different expectations of what such a course should be like. I hope that I have nevertheless managed to write a book that can satisfy the needs of these different target audiences. The lectures themselves, of course, need to be adapted to the needs of each group of students. An engineering student will not qu- tion a statement like “the velocity of the electrons in atoms is ?1% of the velocity of light”, a physics student will. Regarding units, I have written factors h and c explicitly in all equations throughout the book. For physics students it would be preferable to use the convention that is common in physics and omit these constants in the equations, but that would probably be confusing for the engineering students. Physics students tend to be more interested in theoretical physics courses. However, physics is an experimental science and physics students should und- stand how experiments work, and be able to make experiments work. This is an open access book. ; I have been teaching courses on experimental techniques in nuclear and particle physics to master students in physics and in engineering for many years. This book grew out of the lecture notes I made for these students. The physics and engineering students have rather different expectations of what such a course should be like. I hope that I have nevertheless managed to write a book that can satisfy the needs of these different target audiences. The lectures themselves, of course, need to be adapted to the needs of each group of students. An engineering student will not qu- tion a statement like “the velocity of the electrons in atoms is ?1% of the velocity of light”, a physics student will. Regarding units, I have written factors h and c explicitly in all equations throughout the book. For physics students it would be preferable to use the convention that is common in physics and omit these constants in the equations, but that would probably be confusing for the engineering students. Physics students tend to be more interested in theoretical physics courses. However, physics is an experimental science and physics students should und- stand how experiments work, and be able to make experiments work.
Global polarization of Λ hyperons has been measured to be of the order of a few tenths of a percent in Au+Au collisions at √SNN = 200 GeV, with no significant difference between Λ and Λ¯. These new ...results reveal the collision energy dependence of the global polarization together with the results previously observed √SNN = 7.7 – 62.4 GeV and indicate noticeable vorticity of the medium created in non-central heavy-ion collisions at the highest RHIC collision energy.
The role that neutrinos have played in the evolution of the Universe is the focus of one of the most fascinating research areas that has stemmed from the interplay between cosmology, astrophysics and ...particle physics. In this self-contained book, the authors bring together all aspects of the role of neutrinos in cosmology, spanning from leptogenesis to primordial nucleosynthesis, their role in CMB and structure formation, to the problem of their direct detection. The book starts by guiding the reader through aspects of fundamental neutrino physics, such as the standard cosmological model and the statistical mechanics in the expanding Universe, before discussing the history of neutrinos in chronological order from the very early stages until today. This timely book will interest graduate students and researchers in astrophysics, cosmology and particle physics, who work with either a theoretical or experimental focus.
The cross sections of e+e-→π+π-hc at center-of-mass energies from 3.896 to 4.600 GeV are measured using data samples collected with the BESIII detector operating at the Beijing Electron Positron ...Collider. The cross sections are found to be of the same order of magnitude as those of e+e-→π+π- J/ψ and e+e-→π+π-ψ (2S), but the line shape is inconsistent with the Y states observed in the latter two modes. Two structures are observed in the e+e- → π+π- hc cross sections around 4.22 and 4.39 GeV / c 2 , which we call Y ( 4220 ) and Y ( 4390 ) , respectively. A fit with a coherent sum of two Breit-Wigner functions results in a mass of (4218.4 $+5.5\atop{-4.5 ± 0.9) MeV/c2 and a width of 66.0$+12.3\atop-8.3$±0.4 MeV for the Y (4220), and a mass of (4391.5 $+6.3\atop-16.8$ ± 1.0) MeV/c2 and a width of (139.5$+16.2\atop-20.6 ± 0.6) MeV for the Y (4390), where the first uncertainties are statistical and the second ones systematic. The statistical significance of Y ( 4220 ) and Y(4390) is 10σ over one structure assumption.
Electron-ion collider in China Anderle, Daniele P.; Bertone, Valerio; Cao, Xu ...
Frontiers of physics,
12/2021, Volume:
16, Issue:
6
Journal Article
Peer reviewed
Open access
Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion ...collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a po- larization of 80%) and protons (with a polarization of 70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2-3)×10 33 cm −2*s −1. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.
The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.
This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.
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