Nuclear Theory·nucl-th
12 papers—6 primary·6 cross-listed
Chiral effective field theory is being developed into a precision tool for low-energy nuclear physics. I review the state of the art in the two-nucleon sector, discuss applications to few-nucleon systems and address challenges that will have to be faced over the coming years.
The deuteron form factors are calculated using two model wave functions obtained from the 2007 CST high precision fits to scattering data. Included in the calculation are a new class of isoscalar interaction currents which are automatically generated by the nuclear force model used in these fits. If the nuclear model WJC2 is used, a precision fit (/datum ) to the Sick Global Analysis (GA) of all elastic scattering data can be obtained by adjusting the unknown off-shell nucleon form factors (discussed before) and (introduced in this paper), and predicting the high behavior of the neutron charge form factor well beyond the region where it has been measured directly. Relativistic corrections, isoscalar interaction currents, and off-shell effects are defined, discussed, and their size displayed. A rationale for extending elastic scattering measurements to higher is presented.
Xiao-Tao He · Shu-Yong Zhao · Zhen-Hua Zhang · Zhong-Zhou Ren
The multi-particle states and rotational properties of two-particle bands in No are investigated by the cranked shell model (CSM) with pairing correlations treated by a particle-number conserving (PNC) method. For the first time, the rotational bands on top of two-particle and states and the pairing reduction are studied theoretically in No. The experimental excitation energies and moments of inertia for the multi-particle state are reproduced well by the calculation. Better agreement with the data are achieved by including the high-order deformation which leads to enlarged and deformed shell gaps. The rise of the in these two-particle bands compared with the ground-state band is attributed to the pairing reduction due to the Pauli blocking effects.
Bengt Friman🇩🇪 · Wolfram Weise🇩🇪
The equation of state (EoS) of neutron star matter, constrained by the existence of two-solar-mass stars and gravitational wave signals from neutron star mergers, is analysed using the Landau theory of relativistic Fermi liquids. While the phase diagram of dense and cold QCD matter is still open for scenarios ranging from hadronic to quark matter in the center of neutron stars, a Fermi-liquid treatment is motivated by a microscopic approach starting from a chiral nucleon-meson field theory combined with nonperturbative functional renormalization group methods. In this scheme effects of multipionic fluctuations and repulsive nuclear many-body correlations suggest that the transition to chiral symmetry restoration is shifted to densities above those typically encountered in the neutron star core. Under such conditions a Fermi-liquid description in terms of nucleon quasiparticles appears to be justified. The leading Landau parameters are derived and discussed. Our results are contrasted with a well-known Fermi liquid, namely liquid He.
Fernando G. Gardim🇧🇷 · Giuliano Giacalone🇫🇷 · Matthew Luzum🇧🇷 · Jean-Yves Ollitrault🇫🇷
Collisions between heavy atomic nuclei at ultra-relativistic energies are carried out at particle colliders to produce the quark-gluon plasma, a state of matter where quarks and gluons are not confined into hadrons, and colour degrees of freedom are liberated. This state is thought to be produced as a transient phenomenon before it fragments into thousands of particles that reach the particle detectors. Despite two decades of investigations, one of the big open questions is to obtain an experimental determination of the temperature reached in a heavy-ion collision, and a simultaneous determination of another thermodynamic quantity, such as the entropy density, that would give access to the number of degrees of freedom. Here we obtain the first such determination, utilizing state-of-the-art hydrodynamic simulations. We define an effective temperature, averaged over the space-time evolution of the medium. Then, using experimental data, we determine this temperature, the corresponding entropy density and speed of sound in the matter created in lead-lead collisions at the Large Hadron Collider. Our results agree with first-principles calculations from lattice quantum chromodynamics and confirm that a deconfined phase of matter is indeed produced.
C. G. Payne🇩🇪 · S. Bacca🇩🇪 · G. Hagen🇺🇸 · W. Jiang🇺🇸 · T. Papenbrock🇺🇸
Coherent elastic neutrino scattering on the 40Ar nucleus is computed with coupled-cluster theory based on nuclear Hamiltonians inspired by effective field theories of quantum chromodynamics. Our approach is validated by calculating the charge form factor and comparing it to data from electron scattering. We make predictions for the weak form factor, the neutron radius, and the neutron skin, and estimate systematic uncertainties. The neutron-skin thickness of 40Ar40 is consistent with results from density functional theory. Precision measurements from coherent elastic neutrino-nucleus scattering could potentially be used to extract these observables and help to constrain nuclear models.
first authorsco-authorsvia INSPIRE