Nuclear Theory·nucl-th

Thursday·October 22, 2015

10 papers—5 primary·5 cross-listed

06
[Submitted on 20 Oct 2015] (cross-list from hep-ph)
Roy-Steiner-equation analysis of pion-nucleon scattering
Martin Hoferichter🇺🇸 · Jacobo Ruiz de Elvira🇩🇪 · Bastian Kubis🇩🇪 · Ulf-G. Meißner🇩🇪
We review the structure of Roy-Steiner equations for pion-nucleon scattering, the solution for the partial waves of the t-channel process $π π \to N ˉ N$ , as well as the high-accuracy extraction of the pion-nucleon S-wave scattering lengths from data on pionic hydrogen and deuterium. We then proceed to construct solutions for the lowest partial waves of the s-channel process $π N \to π N$ and demonstrate that accurate solutions can be found if the scattering lengths are imposed as constraints. Detailed error estimates of all input quantities in the solution procedure are performed and explicit parameterizations for the resulting low-energy phase shifts as well as results for subthreshold parameters and higher threshold parameters are presented. Furthermore, we discuss the extraction of the pion-nucleon $σ$ -term via the Cheng-Dashen low-energy theorem, including the role of isospin-breaking corrections, to obtain a precision determination consistent with all constraints from analyticity, unitarity, crossing symmetry, and pionic-atom data. We perform the matching to chiral perturbation theory in the subthreshold region and detail the consequences for the chiral convergence of the threshold parameters and the nucleon mass.
Comments:
101 pages, 28 figures; journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.06039 [pdf]
Phys.Rept.(2016)·324 citations
07
[Submitted on 21 Oct 2015] (cross-list from nucl-ex)
Measurement of the absolute differential cross section of proton-proton elastic scattering at small angles
D. Mchedlishvili🇬🇪 · D. Chiladze🇬🇪 · S. Dymov🇷🇺 · Z. Bagdasarian🇬🇪 · S. Barsov🇷🇺 · R. Gebel🇩🇪 · B. Gou🇨🇳 · M. Hartmann🇩🇪 · A. Kacharava🇩🇪 · I. Keshelashvili🇩🇪 · A. Khoukaz🇩🇪 · P. Kulessa🇵🇱 and 29 other authors
The differential cross section for proton-proton elastic scattering has been measured at a beam energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12-16 degrees to 25-30 degrees, depending on the energy. Absolute normalisations of typically 3% were achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon a partial wave analysis. After extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.06162 [pdf]
PLB(2016)·8 citations
08
[Submitted on 21 Oct 2015] (cross-list from hep-ph)
Etaprime interactions with nucleons and nuclei
Steven D. Bass🇦🇹 · Pawel Moskal🇵🇱
We summarise recent progress in theory and experiment towards understanding etaprime meson interactions with nucleons and nuclei. Highlights include the production mechanism of etaprime mesons in proton-proton collisions close to threshold, the etaprime effective mass shift in nuclei and the determination of the etaprime-nucleon scattering length in free space.
Comments:
12 pages, invited talk at the Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Cracow, Poland, June 7-12 2015. arXiv admin note: substantial text overlap with arXiv:1411.7006, arXiv:1311.7248, arXiv:1411.6978
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.06202 [pdf]
Acta Phys.Polon.B(2016)·11 citations
09
[Submitted on 21 Oct 2015] (cross-list from hep-ph)
Watson's theorem and the $N Δ (1232)$ axial transition
L. Alvarez-Ruso🇪🇸 · E. Hernández🇪🇸 · J. Nieves🇪🇸 · M.J. Vicente Vacas🇪🇸
We present a new determination of the $N Δ$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez {\it et al.} [Phys. Rev. D76, 033005 (2007)] is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_{5}^{A} (0)$ , in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.
Comments:
17 latex pages, 7 figures, 2 tables. Some typos corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.06266 [pdf]
PRD(2016)·54 citations
10
[Submitted on 21 Oct 2015] (cross-list from hep-ph)
Neutral hidden charm pentaquark states $P_{c}^{0} (4380)$ and $P_{c}^{0} (4450)$ in $π^{-} p \to J / ψ n$ reaction
Qi-Fang Lü🇨🇳 · Xiao-Yun Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Xu-Rong Chen🇨🇳 · Yu-Bing Dong🇨🇳
We investigate the neutral hidden charm pentaquark states $P_{c}^{0} (4380)$ and $P_{c}^{0} (4450)$ in $π^{-} p \to J / ψ n$ reaction within an effective Lagrangian approach. The background contributions for the process mainly come from $t$ -channel $π$ and $ρ$ meson exchanges. The contributions of $P_{c}^{0} (4380)$ and $P_{c}^{0} (4450)$ states give clear peak structures in the magnitude of 1 $μ$ b at center of mass energy 4.38 GeV and 4.45 GeV in the total cross sections. Hence, this reaction may provide a new good platform to search for neutral $P_{c}$ states. It is expected that our estimated total cross sections together with the angular distributions can be tested by future experiments at J-PARC.
Comments:
9 pages, 6 figures. minor changes to text and added references
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1510.06271 [pdf]
PRD(2016)·51 citations

Affiliations

first authorsco-authorsvia INSPIRE

Roy-Steiner-equation analysis of pion-nucleon scattering

Measurement of the absolute differential cross section of proton-proton elastic scattering at small angles

Etaprime interactions with nucleons and nuclei

Watson's theorem and the NΔ(1232) axial transition

Neutral hidden charm pentaquark states Pc0​(4380) and Pc0​(4450) in π−p→J/ψn reaction

Affiliations

Watson's theorem and the $N Δ (1232)$ axial transition

Neutral hidden charm pentaquark states $P_{c}^{0} (4380)$ and $P_{c}^{0} (4450)$ in $π^{-} p \to J / ψ n$ reaction