arXiv subjects

Betzalel Bazak

Publications and source records attributed to Betzalel Bazak.

26 records · Page 2Linked to original sources

arXiv2016

The Generalized Nuclear Contact and its Application to the Photoabsorption Cross-Section

Using the zero-range model, it was demonstrated recently that Levinger's quasi-deuteron model can be utilized to extract the nuclear neutron-proton contact. Going beyond the zero-range approximation and considering the full nuclear contact formalism, we rederive here the quasi-deuteron model for the nuclear photoabsorption cross-section and utilize it to establish relations and constrains for the general contact matrix. We also define and demonstrate the importance of the diagonalized nuclear contacts, which can be also relevant to further applications of the nuclear contacts.

nucl-th↗

arXiv2015

Photoassociation of Universal Efimov Trimers

In view of recent experiments in ultracold atomic systems, the photoassociation of Efimov trimers, composed of three identical bosons, is studied utilizing the multipole expansion. We study both the normal hierarchy case, where one-body current is dominant, and the strong hierarchy case, relevant for photoassociation in ultracold atoms, where two-body current is dominant. For identical particles in the normal hierarchy case, the leading contribution comes from the r^2 s-mode operator and from the quadrupole d-mode operator. The s-mode reaction is found to be dominant at low temperature, while as the temperature increases the d-mode becomes as significant. For the strong hierarchy case, the leading contribution comes from a 2-body s-wave δ operator. In both cases log periodic oscillations are found in the cross section. For large but finite scattering length the amplitude of the oscillations becomes larger in comparison to infinite scattering length case. We apply our theory to photoassociation of 7Li ultracold atoms and show a good fit to the available experimental results.

cond-mat.quant-gas↗

arXiv2015

Generalized nuclear contacts and the nucleon's momentum distributions

The general nuclear contact matrices are defined, taking into consideration all partial waves and finite-range interactions, extending Tan's work for the zero range model. The properties of these matrices are discussed and the relations between the contacts and the one-nucleon and two-nucleon momentum distributions are derived. Using these relations, a new asymptotic connection between the one-nucleon and two-nucleon momentum distributions, describing the two-body short-range correlations in nuclei, is obtained. Using available numerical data, we extract few connections between the different contacts and verify their relations to the momentum distributions. The numerical data also allows us to identify the main nucleon momentum range affected by two-body short-range correlations. Utilizing these relations and the numerical data, we also verify a previous independent prediction connecting between the Levinger constant and the contacts. This work provides an important indication for the relevance of the contact formalism to nuclear systems, and should open the path for revealing more useful relations between the contacts and interesting quantities of nuclei and nuclear matter.

nucl-th↗

arXiv2014

Experimental evaluation of the nuclear neutron-proton contact

The nuclear neutron-proton contact is introduced, generalizing Tan's work, and evaluated from medium energy nuclear photodisintegration experiments. To this end we reformulate the quasi-deuteron model of nuclear photodisintegration and establish the bridge between the Levinger constant and the contact. Using experimental evaluations of Levinger's constant we extract the value of the neutron-proton contact in finite nuclei and in symmetric nuclear matter. Assuming isospin symmetry we propose to evaluate the neutron-neutron contact through measurement of photonuclear spin correlated neutron-proton pairs.

nucl-th↗

arXiv2014

Photo Reactions with Universal Trimers

Considering one-body and two-body currents, we study the photoassociation and photodissociation of universal bosonic trimers. Analyzing the relative importance of these currents we identify two physical scenarios (i) Normal hierarchy, where naive power counting holds and the one-body current dominates, and (ii) Strong hierarchy, where the one-body current is suppressed. For both scenarios we observe that at the high frequency tail, the response function exhibits log periodic oscillations in transition to or from any continuum state regardless of the reaction partial wave channel. In contrast, near threshold log periodic oscillations appear only in the leading $s$-wave components. These oscillations are the fingerprints of universal Efimov physics. We discuss the relevance of this effect to contemporary experiments in ultracold atoms.

cond-mat.quant-gas↗

arXiv2013

Log-Periodic Oscillations in the Photo Response of Efimov Trimers

The photoassociation of Efimov trimer, composed of three identical bosons, is studied utilizing the multipole expansion. For identical particles the leading contribution comes from the r^2 s-mode operator and from the quadrupole d-mode operator. Log-periodic oscillations are found in the photoassociation response function, both near the energy threshold for the leading s-wave reaction, and in the high frequency tail for all partial waves.

cond-mat.quant-gas↗

arXiv2012

Multipole Analysis of Radio-Frequency Reactions in Ultra-Cold Atoms

Using the multipole expansion we analyze photo induced reactions in an ultra-cold atomic gas composed of identical neutral bosons. While the Frank-Condon factor dominates the photo induced spin-flip reactions, we have found that for frozen-spin process where the atomic spins are conserved the reaction rate is governed by the monopole $r^2$ and the quadrupole terms. Consequently, the dependence of the frozen-spin reaction rate on the photon wave number $k$ acquires an extra $k^4$ factor in comparison to the spin-flip process. Comparing the relative strength of the $r^2$ and quadrupole modes in dimer photoassociation we predict that the mutual importance of these two modes changes with temperature and scattering length.

cond-mat.quant-gas↗

arXiv2011

Gapless Superfluid in $SU(2n+1)$ Fermions Systems

We investigate the generalized Hubbard model of $(2n+1)$ Fermion species interacting via a symmetric contact attraction potential. We prove that the ground state of such system is a gapless superfluid, where a full Fermi surface coexists with a superfluid. Moreover, doing so we prove the existence of a free mode in a strongly interacting system, regardless of the potential strength. This proof holds at the mean field level. A Grassmannian Gaussian integration technique is used to deal with the problem. Our predictions may be relevant to future high-spin cold atoms experiments.

cond-mat.supr-con↗