Nuclear Theory·nucl-th

Thursday·February 12, 2015

7 papers—4 primary·3 cross-listed

01
[Submitted on 11 Feb 2015]
Eta-nuclear interaction: optical vs. coupled channels
J. A. Niskanen🇫🇮
The existence of etamesic nuclei has been speculated for a long time without firm experimental evidence. Much of the effort has taken place in final state interactions on production. One crucial factor in seeing a quasibound state is its width, which should be related to the imaginary part of the scattering length. Comparing two models for eta-N scattering giving the same elementary scattering length, a simple optical potential and an explicit coupling to the pionic channel, it is seen that the latter yields a much smaller imaginary part for eta-nucleus scattering. This decrease of absorption may also mean a possibility for narrow eta-nuclear states.
Comments:
15 pages, 4 figures, verbal clarifications added, Conclusion extended
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1502.03278 [pdf]
PRC(2015)·13 citations
02
[Submitted on 11 Feb 2015]
Determination of the structure of the $X (3872)$ in $p ˉ A$ collisions
A.B. Larionov🇩🇪 · M. Strikman🇺🇸 · M. Bleicher🇩🇪
Currently, the structure of the $X (3872)$ meson is unknown. Different competing models of the $c c ˉ$ exotic state $X (3872)$ exist, including the possibilities that this state is either a mesonic molecule with dominating $D^{0} D ˉ^{* 0} + c . c .$ composition, a $c c ˉ q q ˉ$ tetraquark, or a $c c ˉ$ -gluon hybrid state. It is expected that the $X (3872)$ state is rather strongly coupled to the $p ˉ p$ channel and, therefore, can be produced in $p ˉ p$ and $p ˉ A$ collisions at PANDA. We propose to test the hypothetical molecular structure of $X (3872)$ by studying the $D$ or $D ˉ^{*}$ stripping reactions on a nuclear residue.
Comments:
19 pages, 8 figures; version accepted in PLB
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1502.03311 [pdf]
PLB(2015)·11 citations
03
[Submitted on 11 Feb 2015]
Solid-state calculation of crystalline color superconductivity
Gaoqing Cao🇨🇳 · Lianyi He🇺🇸 · Pengfei Zhuang🇨🇳
It is generally believed that the inhomogeneous Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase appears in a color superconductor when the pairing between different quark flavors is under the circumstances of mismatched Fermi surfaces. However, the real crystal structure of the LOFF phase is still unclear because an exact treatment of 3D crystal structures is rather difficult. In this work we present a solid-state-like calculation of the ground-state energy of the body-centered cubic (BCC) structure for two-flavor pairing by diagonalizing the Hamiltonian matrix in the Bloch space without assuming a small amplitude of the order parameter. We develop a computational scheme to overcome the difficulties in diagonalizing huge matrices. Our results show that the BCC structure is energetically more favorable than the 1D modulation in a narrow window around the conventional LOFF-normal phase transition point, which indicates the significance of the higher-order terms in the Ginzburg-Landau approach.
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1502.03392 [pdf]
PRD(2015)·12 citations
04
[Submitted on 11 Feb 2015]
Relativistic Coulomb scattering of spinless bosons
M. G. Garcia🇧🇷 · A. S. de Castro🇧🇷
The relativistic scattering of spin-0 bosons by spherically symmetric Coulomb fields is analyzed in detail with an arbitrary mixing of vector and scalar couplings. It is shown that the partial wave series reduces the scattering amplitude to the closed Rutherford formula exactly when the vector and scalar potentials have the same magnitude, and as an approximation for weak fields. The behavior of the scattering amplitude near the conditions that furnish its closed form is also discussed. Strong suppressions of the scattering amplitude when the vector and scalar potentials have the same magnitude are observed either for particles or antiparticles with low incident momentum. We point out that such strong suppressions might be relevant in the analysis of the scattering of fermions near the conditions for the spin and pseudospin symmetries. From the complex poles of the partial scattering amplitude the exact closed form of bound-state solutions for both particles and antiparticles with different scenarios for the coupling constants are obtained. Perturbative breaking of the accidental degeneracy appearing in a pair of special cases is related to the nonconservation of the Runge-Lenz vector.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th); Quantum Physics (quant-ph)
arXiv:
1502.03419 [pdf]
PRC(2015)·5 citations
05
[Submitted on 10 Feb 2015] (cross-list from hep-ph)
Constraints on string percolation model from anomalous centrality evolution data in Au-Au collisions at $s_{NN} =$ 62 and 200 GeV
Grigory Feofilov🇷🇺 · Igor Altsybeev🇷🇺 · Olga Kochebina🇫🇷
Anomalous centrality evolution of two-particle angular correlations observed in Au-Au collisions at $s_{N N} = 62$ and 200 GeV and the onset of ridge structures are considered in the model of interacting quark-gluon strings. We assume that at the given energy of nucleus-nucleus collisions the critical energy density may be reached at the specific centrality. In a string percolation model this might be treated equivalently to a formation of a large cluster of strings characterized by the critical string density, with a size comparable to the whole area of interaction of two nuclei. This hypothesis allows to define some constraints on the string percolation model using data on transitional centralities in Au-Au collisions at these two energies. Results are extrapolated to the LHC energy where high string densities (exceeding the critical value) are confirmed for all classes of centralities in Pb-Pb collisions. Interaction between strings inside large clusters formed in nucleus-nucleus collisions is considered in a simplified Monte Carlo model. This model is applied to the qualitative analysis of the onset of collectivity and the ridge formation in Pb-Pb collisions. It is shown that the approach of the repulsive string-string interaction is capable to explain the appearance of elliptic and triangular flow observed in nucleus-nucleus collisions at RHIC and LHC energies.
Comments:
11 pages, 5 figures, proc. Baldin ISHEPP XXII; PoS (Baldin ISHEPP XXII) 067 (2015)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1502.03144 [pdf]
PoS(2015)·2 citations
06
[Submitted on 11 Feb 2015] (cross-list from hep-ph)
Hypothesis about semi-weak interaction and experiments with solar neutrinos
L.M. Slad🇷🇺
A new concept is proposed to solve the solar neutrino problem, that is based on a hypothesis about the existence of semi-weak interaction of electron neutrinos with nucleons mediated by massless pseudoscalar bosons. Owing to about 10 collisions of a solar neutrino with nucleons of the Sun, the fluxes of left- and right-handed solar neutrinos at the Earth surface are approximately equal, and their spectrum is changed in comparison with the one at the production moment. The postulated model with one free parameter provides a good agreement between the calculated and experimental characteristics of the processes with solar neutrinos: $^{37} Cl \to^{37} Ar$ , $^{71} Ga \to^{71} Ge$ , $ν_{e} e^{-} \to ν_{e} e^{-}$ , and $ν_{e} D \to e^{-} pp$ .
Comments:
12 pages. The main material is contained in JETP 129 (2019) 973
Subjects:
High Energy Physics — Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1502.03262 [pdf]
4 citations
07
[Submitted on 11 Feb 2015] (cross-list from hep-ph)
Self-consistent statistical error analysis of $π π$ scattering
R. Navarro Pérez🇪🇸 · E. Ruiz Arriola🇪🇸 · J. Ruiz de Elvira🇩🇪
We analyze the conditions under which a statistical error analysis can be carried out in the case of $π π$ scattering, namely the normality of residuals in the conventional $χ^{2}$ -fit method. Here we check that the current and benchmarking analyses only present very small violations of the normality requirements. In particular, we show how it is possible to amend slightly the selection of the experimental data, and improve the normality of residuals. As an example, we discuss the $0^{++}$ channel and the implications for the $f_{0} (500)$ and $f_{0} (980)$ resonances, obtaining that the new selection of data provides very similar and compatible results. In addition, the effect on the $f_{0} (500)$ and $f_{0} (980)$ resonance pole parameters is almost negligible, which reinforces the central results and the uncertainty analysis performed in these benchmarking determinations.
Comments:
17 pg, 22 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1502.03361 [pdf]
PRD(2015)·32 citations

Affiliations

first authorsco-authorsvia INSPIRE

Eta-nuclear interaction: optical vs. coupled channels

Determination of the structure of the X(3872) in pˉ​A collisions

Solid-state calculation of crystalline color superconductivity

Relativistic Coulomb scattering of spinless bosons

Constraints on string percolation model from anomalous centrality evolution data in Au-Au collisions at sNN​​= 62 and 200 GeV

Hypothesis about semi-weak interaction and experiments with solar neutrinos

Self-consistent statistical error analysis of ππ scattering

Affiliations

Determination of the structure of the $X (3872)$ in $p ˉ A$ collisions

Constraints on string percolation model from anomalous centrality evolution data in Au-Au collisions at $s_{NN} =$ 62 and 200 GeV

Self-consistent statistical error analysis of $π π$ scattering