More Like this

1. Finite-Temperature Relativistic Nuclear Field Theory: An Application to the Dipole Response

   https://doi.org/doi.org/10.1103/PhysRevLett.121.082501  

   Litvinova, E; Wibowo, H (July 2018, Physical review letters)

   Nuclear response theory beyond the one-loop approximation is formulated for the case of finite temperature. For this purpose, the time blocking approximation to the time-dependent part of the in-medium nucleon-nucleon interaction amplitude is adopted for the thermal (imaginary-time) Green's function formalism. We found that introducing a soft blocking, instead of a sharp blocking at zero temperature, brings the Bethe-Salpeter equation to a single frequency variable equation also at finite temperatures. The method is implemented self-consistently in the framework of Quantum Hadrodynamics and designed to connect the high-energy scale of heavy mesons and the low-energy domain of nuclear medium polarization effects in a parameter-free way. In this framework, we investigate the temperature dependence of dipole spectra in the even-even nuclei $$^{48}$$Ca and $$^{100,120,132}$$Sn with a special focus on the giant dipole resonance's width problem and on the low-energy dipole strength distribution. 

   more » « less
2. Spectral action in matrix form

   https://doi.org/10.1140/epjc/s10052-020-08618-z  

   Chamseddine, Ali H.; Iliopoulos, John; van Suijlekom, Walter D. (November 2020, The European Physical Journal C)

   null (Ed.)

   Abstract Quantization of the noncommutative geometric spectral action has so far been performed on the final component form of the action where all traces over the Dirac matrices and symmetry algebra are carried out. In this work, in order to preserve the noncommutative geometric structure of the formalism, we derive the quantization rules for propagators and vertices in matrix form. We show that the results in the case of a product of a four-dimensional Euclidean manifold by a finite space, could be cast in the form of that of a Yang–Mills theory. We illustrate the procedure for the toy electroweak model. 

   more » « less
3. Revisiting proton–proton fusion in chiral effective field theory

   https://doi.org/10.1088/1361-6471/ace3e2  

   Acharya, Bijaya; Marcucci, Laura Elisa; Platter, Lucas (July 2023, Journal of Physics G: Nuclear and Particle Physics)

   Abstract We calculate the S -factor for proton–proton fusion using chiral effective field theory interactions and currents. By performing order-by-order calculations with a variety of chiral interactions that are regularized and calibrated in different ways, we assess the uncertainty in the S -factor from the truncation of the effective field theory expansion and from the sensitivity of the S -factor to the short-distance axial current determined from three- and four-nucleon observables. We find that S (0) = (4.100 ± 0.024(syst) ± 0.013(stat) ± 0.008( g A )) × 10 −23 MeV fm 2 , where the three uncertainties arise, respectively, from the truncation of the effective field theory expansion, use of the two-nucleon axial current fit to few-nucleon observables and variation of the axial coupling constant within the recommended range. The increased value of S (0) compared to previous calculations is mainly driven by an increase in the recommended value for the axial coupling constant and is in agreement with a recent analysis based on pionless effective field theory. 

   more » « less
4. On the dynamical kernels of fermionic equations of motion in strongly-correlated media

   https://doi.org/10.1140/epja/s10050-023-01198-y  

   Litvinova, Elena (December 2023, The European Physical Journal A)

   Blaschke, David (Ed.)

   Two-point fermionic propagators in strongly-correlated media are considered with an emphasis on the dynamical interaction kernels of their equations of motion (EOM). With the many-body Hamiltonian confined by a two-body interaction, the EOMs for the two-point fermionic propagators acquire the Dyson form and, before taking any approximation, the interaction kernels decompose into the static and dynamical (time-dependent) contributions. The latter translate to the energy-dependent and the former map to the energy-independent terms in the energy domain. We dwell particularly on the energy-dependent terms, which generate long-range correlations while making feedback on their short-range static counterparts. The origin, forms, and various approximations for the dynamical kernels of one-fermion and two-fermion propagators, most relevant in the intermediate-coupling regime, are discussed. Applications to the electromagnetic dipole response of 68,70-Ni and low-energy quadrupole response of 114,116,124-Sn are presented. 

   more » « less
5. Studying short-range nuclear correlations using relativistic heavy-ion collisions

   https://doi.org/10.1051/epjconf/202429610011  

   Luzum, Matthew; Picchetti, João Paulo; Hippert, Mauricio; Ollitrault, Jean-Yves (January 2024, EPJ Web of Conferences)

   Bellwied, R; Geurts, F; Rapp, R; Ratti, C; Timmins, A; Vitev, I (Ed.)

   Recently, a method was developed for implementing arbitrary shortrange nucleon-nucleon correlations in Monte Carlo sampled nuclei (as well as deformations of the 1-body nuclear density). We use this method to implement realistic 2-body correlations in a sample of nuclei for use in simulations of relativistic heavy-ion collisions and we quantify the statistical benefits. These results demonstrate that the method can be used to easily implement an arbitrary correlation function, and systematically study the effects of correlations using significantly less resources than is necessary with traditional methods. 

   more » « less