Nuclear Theory·nucl-th

Tuesday·February 4, 2020

12 papers—9 primary·3 cross-listed

10
Consistency checks for two-body finite-volume matrix elements: II. Perturbative systems
Raúl A. Briceño🇺🇸 · Maxwell T. Hansen🇨🇭 · Andrew W. Jackura🇺🇸
Using the general formalism presented in Refs. [1,2], we study the finite-volume effects for the $2 + J \to 2$ matrix element of an external current coupled to a two-particle state of identical scalars with perturbative interactions. Working in a finite cubic volume with periodicity $L$ , we derive a $1/ L$ expansion of the matrix element through $O (1/ L^{5})$ and find that it is governed by two universal current-dependent parameters, the scalar charge and the threshold two-particle form factor. We confirm the result through a numerical study of the general formalism and additionally through an independent perturbative calculation. We further demonstrate a consistency with the Feynman-Hellmann theorem, which can be used to relate the $1/ L$ expansions of the ground-state energy and matrix element. The latter gives a simple insight into why the leading volume corrections to the matrix element have the same scaling as those in the energy, $1/ L^{3}$ , in contradiction to earlier work, which found a $1/ L^{2}$ contribution to the matrix element. We show here that such a term arises at intermediate stages in the perturbative calculation, but cancels in the final result.
↳ hep-lathep-phnucl-thPRD(2020)·29 citations
11
Measurement of the Spectral Shape of the beta-decay of 137Xe to the Ground State of 137Cs in EXO-200 and Comparison with Theory
S. Al Kharusi🇨🇦 · G. Anton🇩🇪 · I. Badhrees🇸🇦 · P.S. Barbeau🇺🇸 · D. Beck🇺🇸 · V. Belov🇷🇺 · T. Bhatta🇺🇸 · M. Breidenbach🇺🇸 · T. Brunner🇨🇦 · G.F. Cao🇨🇳 · W.R. Cen🇨🇳 · C. Chambers🇨🇦 and 96 other authors
We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden non-unique $β$ -decay transition $^{137} Xe (7/ 2^{-}) \to^{137} Cs (7/ 2^{+})$ . The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultra-low background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal-to-background ratio of more than 99-to-1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden non-unique $β$ -decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.
↳ nucl-exnucl-thPRL(2020)·11 citations
12
All-order momentum correlations of three ultracold bosonic atoms confined in triple-well traps: Signatures of emergent many-body quantum phase transitions and analogies with three-photon quantum-optics interference
Constantine Yannouleas · Uzi Landman
All-order momentum correlation functions associated with the time-of-flight spectroscopy of three spinless ultracold bosonic interacting neutral atoms confined in a linear three-well optical trap are presented. The underlying Hamiltonian employed for the interacting atoms is an augmented three-site Hubbard model. Our investigations target matter-wave interference of massive particles, aiming at the establishment of experimental protocols for characterizing the quantum states of trapped attractively or repulsively interacting ultracold particles, with variable interaction strength. The manifested advantages and deep physical insights that can be gained through the employment of the results of our study for a comprehensive understanding of the nature of the quantum states of interacting many-particle systems, via analysis of the all-order (that is 1st, 2nd and 3rd) momentum correlation functions for three bosonic atoms in a three well confinement, are illustrated and discussed in the context of time-of-flight inteferometric interrogations of the interaction-strength-induced emergent quantum phase transition from the Mott insulating phase to the superfluid one. Furthermore, we discuss that our inteferometric interrogations establish strong analogies with the quantum-optics interference of three photons, including the aspects of genuine three-photon interference, which are focal to explorations targeting the development and implementation of quantum information applications and quantum computing.
↳ cond-mat.quant-gasnucl-thquant-phPRA(2020)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Consistency checks for two-body finite-volume matrix elements: II. Perturbative systems

Measurement of the Spectral Shape of the beta-decay of 137Xe to the Ground State of 137Cs in EXO-200 and Comparison with Theory

All-order momentum correlations of three ultracold bosonic atoms confined in triple-well traps: Signatures of emergent many-body quantum phase transitions and analogies with three-photon quantum-optics interference

Affiliations