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Nuclear Theory·nucl-th

Wednesday·April 5, 2017

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 03

    [Submitted on 17 Dec 2016] (cross-list from cond-mat.quant-gas)

    Trimer and Tetramer Bound States in Heteronuclear Systems

    Christiane H. Schmickler · Hans-Werner Hammer · Emiko Hiyama

    The Efimov effect in heteronuclear cold atomic systems is experimentally more easily accessible than the Efimov effect for identical atoms, because of the potentially smaller scaling factor. We focus on the case of two or three heavy identical bosons and another atom. The former case was recently observed in a mixture of 133Cs and 6Li atoms. We employ the Gaussian Expansion Method as developed by Hiyama, Kino et al.. This is a variational method that uses Gaussians that are distributed geometrically over a chosen range. Supplemental calculations are performed using the Skorniakov-Ter-Martirosian equation. Blume et al. previously investigated the scaling properties of heteronuclear systems in the unitary limit and at the three-body breakup threshold. We have completed this picture by calculating the behaviour on the positive scattering length side of the Efimov plot, focussing on the dimer threshold.

    Comments:
    4 pages, 4 figures, proceedings of EFB23; corrected typos
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
    arXiv:
    1612.05738 [pdf]
    Few Body Syst.(2017)·2 citations
  2. 04

    [Submitted on 3 Apr 2017] (cross-list from cond-mat.quant-gas)

    Analytical approach to the Bose polaron problem in one dimension

    A. G. Volosniev · H.-W. Hammer

    We discuss the ground state properties of a one-dimensional bosonic system doped with an impurity (the so-called Bose polaron problem). We introduce a formalism that allows us to calculate analytically the thermodynamic zero-temperature properties of this system with weak and moderate boson-boson interaction strengths for any boson-impurity interaction. Our approach is validated by comparing to exact quantum Monte Carlo calculations. In addition, we test the method in finite size systems using numerical results based upon the similarity renormalization group. We argue that the introduced approach provides a simple analytical tool for studies of strongly interacting impurity problems in one dimension.

    Comments:
    Version accepted for publication
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
    arXiv:
    1704.00622 [pdf]
    PRA(2017)·53 citations
  3. 05

    [Submitted on 4 Apr 2017] (cross-list from cond-mat.quant-gas)

    Strong-coupling corrections to ground-state properties of a superfluid Fermi gas

    Hiroyuki Tajima · Pieter van Wyk · Ryo Hanai · Daichi Kagamihara · Daisuke Inotani · Munekazu Horikoshi · Yoji Ohashi

    We theoretically present an economical and convenient way to study ground-state properties of a strongly interacting superfluid Fermi gas. Our strategy is that complicated strong-coupling calculations are used only to evaluate quantum fluctuation corrections to the chemical potential . Then, without any further strong-coupling calculations, we calculate the compressibility, sound velocity, internal energy, pressure, and Tan's contact, from the calculated without loss of accuracy, by using exact thermodynamic identities. Using a recent precise measurement of in a superfluid Li Fermi gas, we show that an extended -matrix approximation (ETMA) is suitable for our purpose, especially in the BCS-unitary regime, where our results indicate that many-body corrections are dominated by superfluid fluctuations. Since precise determinations of physical quantities are not always easy in cold Fermi gas physics, our approach would greatly reduce experimental and theoretical efforts toward the understanding of ground-state properties of this strongly interacting Fermi system.

    Comments:
    12 pages, 5 figures, accepted by Physical Review A
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
    arXiv:
    1704.01032 [pdf]
    PRA(2017)·24 citations
  4. 06

    [Submitted on 4 Apr 2017] (cross-list from hep-lat)

    An accurate calculation of the nucleon axial charge with lattice QCD

    Evan Berkowitz🇩🇪 · David Brantley🇺🇸 · Chris Bouchard🇬🇧 · Chia Cheng Chang🇺🇸 · M. A. Clark🇺🇸 · Nicholas Garron🇬🇧 · Balint Joo🇺🇸 · Thorsten Kurth🇺🇸 · Chris Monahan🇺🇸 · Henry Monge-Camacho🇺🇸 · Amy Nicholson🇺🇸 · Kostas Orginos🇺🇸 and 3 other authors

    We report on a lattice QCD calculation of the nucleon axial charge, , using Möbius Domain-Wall fermions solved on the dynamical HISQ ensembles after they are smeared using the gradient-flow algorithm. The calculation is performed with three pion masses, MeV. Three lattice spacings ( fm) are used with the heaviest pion mass, while the coarsest two spacings are used on the middle pion mass and only the coarsest spacing is used with the near physical pion mass. On the MeV, fm point, a dedicated volume study is performed with . Using a new strategy motivated by the Feynman-Hellmann Theorem, we achieve a precise determination of with relatively low statistics, and demonstrable control over the excited state, continuum, infinite volume and chiral extrapolation systematic uncertainties, the latter of which remains the dominant uncertainty. Our final determination at 2.6\% total uncertainty is , with the first uncertainty including statistical and systematic uncertainties from fitting and the second including model selection systematics related to the chiral and continuum extrapolation. The largest reduction of the second uncertainty will come from a greater number of pion mass points as well as more precise lattice QCD results near the physical pion mass.

    Comments:
    17 pages + 11 pages of references and appendices. 15 figures. Interested readers can download the Python analysis scripts and an hdf5 data file at https://github.com/callat-qcd/project_gA_v0
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1704.01114 [pdf]
    72 citations

Affiliations

first authorsco-authorsvia INSPIRE