Nuclear Theory·nucl-th

Monday·May 25, 2015

5 papers—2 primary·3 cross-listed

03
[Submitted on 21 May 2015] (cross-list from hep-ph)
Distinguishing cusp effects and near-threshold-pole effects
Zhi-Yong Zhou🇨🇳 · Zhiguang Xiao🇨🇳
We make use of a unitarized coupled-channel model to analyze the mass distribution data of final states in production processes of $X (4260)$ . By analyzing the analytical structures of the decay amplitudes, we find that the line shape of $Z_{c} (3900)$ signal is related to the combined effect of a pair of near-threshold "shadow" poles and the $(D D ˉ^{*})^{\pm}$ thresholds, in which the third-sheet pole might provide a dominant contribution. As all the coupled channels effects are tuning off, the trajectories of these two poles suggest that the $Z_{c} (3900)$ might originate from the attractive interaction of $(D^{*} D ˉ^{*})^{\pm}$ through a long-distance interaction, $e . g .$ $π$ -exchange interaction, as a "deuteron-like" state. There is no nearby pole structure corresponding to the $Z_{c} (4025)$ signal in the $(D^{*} D ˉ^{*})^{\pm}$ mass distribution.
Comments:
10 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1505.05761 [pdf]
PRD(2015)·19 citations
04
[Submitted on 22 May 2015] (cross-list from hep-ph)
Stable Yang-Lee zeros in truncated fugacity series from net-baryon number multiplicity distribution
Kenji Morita🇯🇵 · Atsushi Nakamura🇯🇵
We investigate Yang-Lee zeros of grand partition functions as truncated fugacity polynomials of which coefficients are given by the canonical partition functions $Z (T, V, N)$ up to $N \leq N_{max}$ . Such a partition function can be inevitably obtained from the net-baryon number multiplicity distribution in relativistic heavy ion collisions, where the number of the event beyond $N_{max}$ has insufficient statistics, as well as canonical approaches in lattice QCD. We use a chiral random matrix model as a solvable model for chiral phase transition in QCD and show that the closest edge of the distribution to real chemical potential axis is stable against cutting the tail of the multiplicity distribution. The similar behavior is also found in lattice QCD at finite temperature for Roberge-Weiss transition. In contrast, such a stability is found to be absent in the Skellam distribution which does not have phase transition. We compare the number of $N_{max}$ to obtain the stable Yang-Lee zeros with those of critical higher order cumulants.
Comments:
15 pages, 9 figures. Version to appear in Phys. Rev. D. Comments on lattice results are added. Typos are corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1505.05985 [pdf]
PRD(2015)·5 citations
05
[Submitted on 22 May 2015] (cross-list from hep-ph)
The $K K ˉ π$ decay of the $f_{1} (1285)$ and its nature as a $K^{*} K ˉ - cc$ molecule
F. Aceti🇪🇸 · Ju-Jun Xie🇨🇳 · E. Oset🇨🇳
We investigate the decay of $f_{1} (1285) \to π K K ˉ$ with the assumption that the $f_{1} (1285)$ is dynamically generated from the $K^{*} K ˉ - cc$ interaction. In addition to the tree level diagrams that proceed via $f_{1} (1285) \to K^{*} K ˉ - cc \to π K K ˉ$ , we take into account also the final state interactions of $K K ˉ \to K K ˉ$ and $π K \to π K$ . The partial decay width and mass distributions of $f_{1} (1285) \to π K K ˉ$ are evaluated. We get a value for the partial decay width which, within errors, is in fair agreement with the experimental result. The contribution from the tree level diagrams is dominant, but the final state interactions have effects in the mass distributions. The predicted mass distributions are significantly different from phase space and tied to the $K^{*} K ˉ - cc$ nature of the $f_{1} (1285)$ state.
Comments:
Published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1505.06134 [pdf]
PLB(2015)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE

Distinguishing cusp effects and near-threshold-pole effects

Stable Yang-Lee zeros in truncated fugacity series from net-baryon number multiplicity distribution

The KKˉπ decay of the f1​(1285) and its nature as a K∗Kˉ−cc molecule

Affiliations

The $K K ˉ π$ decay of the $f_{1} (1285)$ and its nature as a $K^{*} K ˉ - cc$ molecule