Nuclear Theory·nucl-th

Tuesday·March 29, 2016

11 papers—6 primary·5 cross-listed

07
[Submitted on 25 Mar 2016] (cross-list from hep-ph)
Strangeness $S = - 1$ hyperon-nucleon scattering in covariant chiral effective field theory
Kai-Wen Li🇨🇳 · Xiu-Lei Ren🇨🇳 · Li-Sheng Geng🇨🇳 · Bing-Wei Long🇨🇳
Motivated by the successes of covariant baryon chiral perturbation theory in one-baryon systems and in heavy-light systems, we study relevance of relativistic effects in hyperon-nucleon interactions with strangeness $S = - 1$ . In this exploratory work, we follow the covariant framework developed by Epelbaum and Gegelia to calculate the $Y N$ scattering amplitude at leading order. By fitting the five low-energy constants to the experimental data, we find that the cutoff dependence is mitigated, compared with the heavy-baryon approach. Nevertheless, the description of the experimental data remains quantitatively similar at leading order.
Comments:
The manuscript has been largely rewritten but the results remain unchanged. To appear in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1603.07802 [pdf]
PRD(2016)·45 citations
08
[Submitted on 25 Mar 2016] (cross-list from hep-ph)
Update of HKN Nuclear PDFs
Masanori Hirai🇯🇵
We discuss consistency of the nuclear effects between the electromagnetic and weak interactions. In order to study a possibility of different nuclear effects in the neutrino DIS process, double differential cross section data are compared with these values obtained by the HKN07 nuclear parton distribution functions (nPDFs). Discrepancies are found in the small and large- $x$ regions, and difference of kinematical value $y$ dependence exists between the $ν$ and $ν ˉ$ data around $x = 0.35$ . Moreover, we study statistical significance of the neutrino DIS data in each $x$ bin and discuss about the possibility of the different nuclear modifications.
Comments:
8 pages, 6 eps files, JPS Conference Proceedings in press, International workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt15), Osaka, Japan, November 16-21, 2015
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1603.07854 [pdf]
JPS Conf.Proc.(2016)·4 citations
09
[Submitted on 25 Mar 2016] (cross-list from nucl-ex)
The mutable nature of particle-core excitations with spin in the one-valence-proton nucleus 133Sb
G. Bocchi🇮🇹 · S. Leoni🇮🇹 · B. Fornal🇵🇱 · G. Colo'🇮🇹 · P.F. Bortignon🇮🇹 · S. Bottoni🇮🇹 · A. Bracco🇮🇹 · C. Michelagnoli🇫🇷 · D. Bazzacco🇮🇹 · A. Blanc🇫🇷 · G. De France🇫🇷 · M. Jentschel🇫🇷 and 34 other authors
The gamma-ray decay of excited states of the one-valence-proton nucleus 133Sb has been studied using cold-neutron induced fission of 235U and 241Pu targets, during the EXILL campaign at the ILL reactor in Grenoble. By using a highly efficient HPGe array, coincidences between gamma-rays prompt with the fission event and those delayed up to several tens of microseconds were investigated, allowing to observe, for the first time, high-spin excited states above the 16.6 micros isomer. Lifetimes analysis, performed by fast-timing techniques with LaBr3(Ce) scintillators, reveals a difference of almost two orders of magnitude in B(M1) strength for transitions between positive-parity medium-spin yrast states. The data are interpreted by a newly developed microscopic model which takes into account couplings between core excitations (both collective and non-collective) of the doubly magic nucleus 132Sn and the valence proton, using the Skyrme effective interaction in a consistent way. The results point to a fast change in the nature of particle-core excitations with increasing spin.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1603.08056 [pdf]
PLB(2016)·33 citations
10
[Submitted on 27 Mar 2016] (cross-list from nucl-ex)
Transverse wobbling motion in $^{134}$ Ce and $^{136}$ Nd
C. M. Petrache · S. Guo
The existence of one-phonon and possible two-phonon transverse wobbling bands is proposed for the first time in two even-even nuclei, $^{134}$ Ce and $^{136}$ Nd. The predominant $E 2$ character of the $Δ I = 1$ transitions connecting the one-phonon wobbling band in $^{134}$ Ce to the two-quasiparticle yrast band supports the wobbling interpretation. The extracted wobbling frequencies decrease with increasing spin, indicating the transverse character of the wobbling motion, with the angular momenta of the two quasiparticles aligned perpendicular to the axis of collective rotation. A candidate for two-phonon wobbling motion is also proposed in $^{136}$ Nd. The wobbling frequencies calculated in the harmonic frozen approximation are in good agreement with the experimental ones for both the $^{134}$ Ce and $^{136}$ Nd nuclei.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1603.08247 [pdf]
4 citations
11
[Submitted on 28 Mar 2016] (cross-list from cond-mat.str-el)
Progress in Many Body Theory with the Equation of Motion method. Time dependent Density Matrix meets Self-Consistent RPA. Applications to solvable Models
Peter Schuck🇫🇷 · Mitsuru Tohyama🇯🇵
The Bogoliubov-Born-Green-Kirkwood-Yvon or Time-Dependent Density Matrix (TDDM) hierarchy of equations for higher density matrices is truncated at the three body level in approximating the three body correlation function by a quadratic form of two body ones, closing the equations in this way. The procedure is discussed in detail and it is shown in non-trivial model cases that the approximate inclusion of three body correlation functions is very important to obtain precise results. A small amplitude approximation of this time dependent nonlinear equation for the two body correlation function is performed (STDDM*-b) and it is shown that the one body sector of this generalised non-linear second RPA equation is equivalent to the Self-Consistent RPA (SCRPA) approach which had been derived previously by different techniques. It is discussed in which way SCRPA also contains the three body correlations. TDDM and SCRPA are tested versus exactly solvable model cases.
Comments:
27 pages, 14 figures
Subjects:
Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
1603.08276 [pdf]
PRB(2016)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE

Strangeness S=−1 hyperon-nucleon scattering in covariant chiral effective field theory

Update of HKN Nuclear PDFs

The mutable nature of particle-core excitations with spin in the one-valence-proton nucleus 133Sb

Transverse wobbling motion in 134Ce and 136Nd

Progress in Many Body Theory with the Equation of Motion method. Time dependent Density Matrix meets Self-Consistent RPA. Applications to solvable Models

Affiliations

Strangeness $S = - 1$ hyperon-nucleon scattering in covariant chiral effective field theory

Transverse wobbling motion in $^{134}$ Ce and $^{136}$ Nd