Nuclear Theory·nucl-th

Thursday·May 21, 2015

9 papers—4 primary·5 cross-listed

05
[Submitted on 26 Mar 2015] (cross-list from math-ph)
Bethe states for the two-site Bose-Hubbard model: a binomial approach
Gilberto Santos🇧🇷 · Changrim Ahn🇰🇷 · Angela Foerster🇧🇷 · Itzhak Roditi🇧🇷
We calculate explicitly the Bethe vectors states by the algebraic Bethe ansatz method with the $g l (2)$ -invariant $R$ -matrix for the two-site Bose-Hubbard model. Using a binomial expansion of the n-th power of a sum of two operators we get and solve a recursion equation. We calculate the scalar product and the norm of the Bethe vectors states. The form factors of the imbalance current operator are also computed.
Comments:
13 pages
Subjects:
Mathematical Physics (math-ph); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Theory (hep-th); math.MP (math.MP); nlin.SI (nlin.SI); Nuclear Theory (nucl-th)
arXiv:
1503.07885 [pdf]
PLB(2015)·11 citations
06
[Submitted on 19 May 2015] (cross-list from astro-ph.HE)
The Dense Matter Equation of State from Neutron Star Radius and Mass Measurements
Feryal Ozel · Dimitrios Psaltis · Tolga Guver · Gordon Baym · Craig Heinke · Sebastien Guillot
We present a comprehensive study of spectroscopic radius measurements of twelve neutron stars obtained during thermonuclear bursts or in quiescence. We incorporate, for the first time, a large number of systematic uncertainties in the measurement of the apparent angular sizes, Eddington fluxes, and distances, in the composition of the interstellar medium, and in the flux calibration of X-ray detectors. We also take into account the results of recent theoretical calculations of rotational effects on neutron star radii, of atmospheric effects on surface spectra, and of relativistic corrections to the Eddington critical flux. We employ Bayesian statistical frameworks to obtain neutron star radii from the spectroscopic measurements as well as to infer the equation of state from the radius measurements. Combining these with the results of experiments in the vicinity of nuclear saturation density and the observations of ~2 Msun neutron stars, we place strong and quantitative constraints on the properties of the equation of state between approximately 2-8 times the nuclear saturation density. We find that around M=1.5 Msun, the preferred equation of state predicts radii between 10.1 - 11.1 km. When interpreting the pressure constraints in the context of high density equations of state based on interacting nucleons, our results suggest a relatively weak contribution of the three-body interaction potential.
Comments:
ApJ, in press. Revised version includes more expanded analyses and discussions of comparison to previous results
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1505.05155 [pdf]
ApJ(2016)·366 citations
07
[Submitted on 19 May 2015] (cross-list from astro-ph.HE)
Statistics of Measuring Neutron Star Radii: Assessing A Frequentist and A Bayesian Approach
Feryal Ozel · Dimitrios Psaltis
Measuring neutron star radii with spectroscopic and timing techniques relies on the combination of multiple observables to break the degeneracies between the mass and radius introduced by general relativistic effects. Here, we explore a previously used frequentist and a newly proposed Bayesian framework to obtain the most likely value and the uncertainty in such a measurement. We find that, for the expected range of masses and radii and for realistic measurement errors, the frequentist approach suffers from biases that are larger than the accuracy in the radius measurement required to distinguish between the different equations of state. In contrast, in the Bayesian framework, the inferred uncertainties are larger, but the most likely values do not suffer from such biases. We also investigate ways of quantifying the degree of consistency between different spectroscopic measurements from a single source. We show that a careful assessment of the systematic uncertainties in the measurements eliminates the need for introducing ad hoc biases, which lead to artificially large inferred radii.
Comments:
ApJ, in press
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1505.05156 [pdf]
ApJ(2015)·24 citations
08
[Submitted on 19 May 2015] (cross-list from hep-ph)
Implementing the exact kinematical constraint in the saturation formalism
Kazuhiro Watanabe🇨🇳 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸 · David Zaslavsky🇨🇳
We revisit the issue of the large negative next-to-leading order (NLO) cross section for single inclusive hadron production in $p A$ collisions in the saturation formalism. By implementing the exact kinematical constraint in the modified dipole splitting functions, two additional positive NLO correction terms are obtained. In the asymptotic large $k_{⊥}$ limit, we analytically show that these two terms become as large as the negative NLO contributions found in our previous calculation. Furthermore, the numerical results demonstrate that the applicable regime of the saturation formalism can be extended to a larger $k_{⊥}$ window, where the exact matching between the saturation formalism (in the asymptotic $k_{⊥}$ regime) and the collinear factorization calculations will have to be performed separately. In addition, after significantly improving the numerical accuracy of the NLO correction, we obtain excellent agreement with the LHC and RHIC data for forward hadron productions.
Comments:
20 pages, 7 figures; v2 fixes some typos
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1505.05183 [pdf]
PRD(2015)·69 citations
09
[Submitted on 20 May 2015] (cross-list from hep-ph)
$Z_{c} (3900)$ as a resonance from the $D D ˉ^{*}$ interaction
Jun He🇨🇳
In this paper it is proposed that the charged charmonium-like state $Z_{c} (3900)$ is a resonance above the threshold from the $D D ˉ^{*}$ interaction. The $D D ˉ^{*}$ interaction is described by the one-boson exchange model with light meson exchanges plus a short-range $J / ψ$ exchange. The scattering amplitude is calculated within a Bethe-Salpeter equation approach and the poles near the $D D ˉ^{*}$ threshold are searched. In the isoscalar sector, two poles found under the $D D ˉ^{*}$ threshold, i.e., bound states, have the quantum numbers $I^{G} (J^{P C}) = 0^{-} (1^{+-})$ and $0^{+} (1^{++})$ . The latter can be related to the $X (3872)$ . In the isovector sector, a bound state with $I^{G} (J^{P}) = 1^{+} (1^{+})$ is found with a large cutoff at about 3 GeV. If a cutoff at about 2 GeV is adopted with which a pole carrying the quantum number of the $X (3872)$ is produced at an energy of about 3871 MeV, the pole for the bound state with $1^{+} (1^{+})$ runs across the threshold to a second Rienman sheet and becomes a resonance above the $D D ˉ^{*}$ threshold, which can be identified with the $Z_{c} (3900)$ . With such a cutoff, the $D D ˉ^{*}$ invariant mass spectrum is also investigated and the experimental results found by BESIII can be reproduced.
Comments:
7 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1505.05379 [pdf]
PRD(2015)·85 citations

Affiliations

first authorsco-authorsvia INSPIRE

Bethe states for the two-site Bose-Hubbard model: a binomial approach

The Dense Matter Equation of State from Neutron Star Radius and Mass Measurements

Statistics of Measuring Neutron Star Radii: Assessing A Frequentist and A Bayesian Approach

Implementing the exact kinematical constraint in the saturation formalism

Zc​(3900) as a resonance from the DDˉ∗ interaction

Affiliations

$Z_{c} (3900)$ as a resonance from the $D D ˉ^{*}$ interaction