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We discuss advanced statistical methods to improve parameter estimation of nuclear models. In particular, using the Liquid Drop Model for nuclear binding energies, we show that the area around the global $\chi^2$ minimum can be efficiently…

Nuclear Theory · Physics 2018-11-26 M. Shelley , P. Becker , A. Gration , A. Pastore

Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective field theory interactions. In this work, we present a detailed description of the auxiliary field…

Nuclear Theory · Physics 2018-05-02 D. Lonardoni , S. Gandolfi , J. E. Lynn , C. Petrie , J. Carlson , K. E. Schmidt , A. Schwenk

The nuclear shell model is known to describe the properties of various nuclei extremely well. However, the auxiliary-field quantum Monte Carlo calculations cannot be applied to it with general interactions due to the sign problem. The model…

Nuclear Theory · Physics 2025-08-22 Yuhma Asano , Yuta Ito , Jun Nishimura , Noritaka Shimizu

We review results obtained using Shell Model Monte Carlo (SMMC) techniques. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; the…

Nuclear Theory · Physics 2009-10-30 S. E. Koonin , D. J. Dean , K. Langanke

There is increasing interest in using high-energy collisions to probe the structure of nuclei, in particular with the high-precision data made possible by collisions performed with pairs of isobaric species. A systematic study requires a…

Nuclear Theory · Physics 2023-05-26 Matthew Luzum , Mauricio Hippert , Jean-Yves Ollitrault

The dependence of the nuclear level density on intrinsic deformation is an important input to dynamical nuclear processes such as fission. Auxiliary-field Monte Carlo (AFMC) method is a powerful method for computing nuclear level densities.…

Nuclear Theory · Physics 2018-09-26 M. T. Mustonen , C. N. Gilbreth , Y. Alhassid , G. F. Bertsch

We develop a shell-model Monte Carlo (SMMC) method to calculate densities of states with varying exciton (particle-hole) number. We then apply this method to the doubly closed-shell nucleus 40Ca in a full 0s-1d-0f-1p shell-model space and…

Nuclear Theory · Physics 2009-10-31 D. J. Dean , S. E. Koonin

A new method for calculation of shell model intrinsic density matrices, defined as two-particle density matrices integrated over the centre-of-mass position vector of two last particles and complemented with isospin variables, has been…

Nuclear Theory · Physics 2007-05-23 A. Deveikis , G. Kamuntavicius

We apply the auxiliary-field Monte Carlo approach to the nuclear shell model in the 1s-0d configuration space. The Hamiltonian was chosen to have isovector pairing and isoscalar multipole-multipole interactions, and the calculations were…

Nuclear Theory · Physics 2008-11-26 W. E. Ormand , D. J. Dean , C. W. Johnson , G. H. Lang , S. E. Koonin

We discuss the role of mean-field and moment methods in microscopic models for calculating the nuclear density of states (also known as the nuclear level density). Working in a shell-model framework, we use moments of the nuclear many-body…

Nuclear Theory · Physics 2007-05-23 Calvin W. Johnson , Edgar Teran

We introduce a novel method within the shell model Monte Carlo approach to calculate the ground-state energy of a finite-size system with an odd number of particles by using the asymptotic behavior of the imaginary-time single-particle…

Nuclear Theory · Physics 2015-06-03 Abhishek Mukherjee , Y. Alhassid

We present in detail a formulation of the shell model as a path integral and Monte Carlo techniques for its evaluation. The formulation, which linearizes the two-body interaction by an auxiliary field, is quite general, both in the form of…

Nuclear Theory · Physics 2008-11-26 G. H. Lang , C. W. Johnson , S. E. Koonin , W. E. Ormand

We describe and analyze some Monte Carlo methods for manifolds in Euclidean space defined by equality and inequality constraints. First, we give an MCMC sampler for probability distributions defined by un-normalized densities on such…

Numerical Analysis · Mathematics 2017-09-21 Emilio Zappa , Miranda Holmes-Cerfon , Jonathan Goodman

Variational Monte Carlo and Green's function Monte Carlo are powerful tools for calculations of properties of light nuclei using realistic two-nucleon and three-nucleon potentials. Recently the GFMC method has been extended to multiple…

Nuclear Theory · Physics 2009-11-10 Steven C. Pieper

Nuclear clustering describes the appearance of structures resembling smaller nuclei such as alpha particles (4He nuclei) within the interior of a larger nucleus. While clustering is important for several well-known examples, much remains to…

A new Quantum Monte-Carlo (QMC) approach is proposed to investigate low-lying states of nuclei within the shell model. The formalism relies on a variational symmetry-restored wave-function to guide the underlying Brownian motion. Sign/phase…

Nuclear Theory · Physics 2015-10-20 Jérémy Bonnard , Olivier Juillet

Heavy nuclei exhibit a crossover from vibrational to rotational collectivity as the number of neutrons or protons increases from shell closure towards midshell, but the microscopic description of this crossover has been a major challenge.…

Nuclear Theory · Physics 2013-02-01 C. Özen , Y. Alhassid , H. Nakada

We review recent experimental and theoretical progress in understanding the microscopic details of clustering in light nuclei. We discuss recent experimental results on $\alpha$-conjugate systems, molecular structures in neutron-rich…

Nuclear Theory · Physics 2018-08-30 Martin Freer , Hisashi Horiuchi , Yoshiko Kanada-En'yo , Dean Lee , Ulf-G. Meißner

Level density $\rho$ is derived for a finite system with strongly interacting nucleons at a given energy E, neutron N and proton Z particle numbers, projection of the angular momentum M, and other integrals of motion, within the…

Nuclear Theory · Physics 2023-08-22 A. G. Magner , A. I. Sanzhur , S. N. Fedotkin , A. I. Levon , U. V. Grygoriev , S. Shlomo

We present an integral density method for calculating the multifractal dimension spectrum for the nucleon distribution in atomic nuclei. This method is then applied to analyze the non-uniformity of the density distribution in several…

Nuclear Theory · Physics 2024-04-12 Weihu Ma , Yu-Gang Ma , Wanbing He , Bo Zhou