Mon·Mar 21, 2016Monday·March 21, 2016

1. 01*

   Single-particle spectral function of the $\Lambda$ hyperon in finite nuclei

   Isaac Vidana🇵🇹

   The spectral function of the $\Lambda$ hyperon in finite nuclei is calculated from the corresponding $\Lambda$ self-energy, which is constructed within a perturbative many-body approach using some of the hyperon-nucleon interactions of the Jülich and Nijmegen groups. Binding energies, wave functions and disoccupation numbers of different single-particle states are obtained for various hypernuclei from ${}_{\Lambda }^5$He to ${}_{\Lambda }^{209}$Pb. The agreement between the calculated binding energies and experimental data is qualitatively good. The small spin-orbit splitting of the $p-,d-,f-$ and $g-$wave states is confirmed. The discrete and the continuum contributions of the single-$\Lambda$ spectral function are computed. Their appearance is qualitatively similar to that of the nucleons. The $Z$-factor, that measures the importance of correlations, is also calculated. Our results show that its value is relatively large, indicating that the $\Lambda$ hyperon is less correlated than nucleons. This is in agreement with the results obtained by other authors for the correlations of the $\Lambda$ in infinite nuclear matter. The disoccupation numbers are obtained by integrating the spectral function over the energy. Our results show that the discrete contribution to the disoccupation number decreases when increasing the momentum of the $\Lambda$. This indicates that, in the production reactions of hypernuclei, the $\Lambda$ hyperon is mostly formed in a quasi-free state.

   ↳ nucl-thhep-phnucl-exNPA(2017)·16 citations
2. 02*

   Hadron-Hadron Correlation and Interaction from Heavy-Ion Collisions

   Akira Ohnishi🇯🇵 · Kenji Morita🇯🇵 · Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵

   We investigate the $\Lambda \Lambda$ and $K^{-}p$ intensity correlations in high-energy heavy-ion collisions. First, we examine the dependence of the $\Lambda \Lambda$ correlation on the $\Lambda \Lambda$ interaction and the $\Lambda \Lambda$ pair purity probability $\lambda$. For small $\lambda$, the correlation function needs to be suppressed by the $\Lambda \Lambda$ interaction in order to explain the recently measured $\Lambda \Lambda$ correlation data. By comparison, when we adopt the $\lambda$ value evaluated from the experimentally measured ${\Sigma }^0/\Lambda$ ratio, the correlation function needs to be enhanced by the interaction. We demonstrate that these two cases correspond to the two analyses which gave opposite signs of the $\Lambda \Lambda$ scattering length. Next, we discuss the $K^{-}p$ correlation function. By using the local $\bar{K}N$ potential which reproduces the kaonic hydrogen data by SIDDHARTA, we obtain the $K^{-}p$ correlation function. We find that the $K^{-}p$ correlation can provide a complementary information with the $K^{-}p$ elastic scattering amplitude.

   ↳ nucl-thhep-phnucl-exNPA(2016)·74 citations
3. 03*

   Formation of deuterons by coalescence: Consequences on the deuteron number fluctuations

   Zuzana Feckova🇸🇰 · Jan Steinheimer🇩🇪 · Boris Tomasik🇸🇰 · Marcus Bleicher🇩🇪

   Two scenarios for cluster production have since long been discussed in the literature: i) direct emission of the clusters from a (grand canonical) thermal source or ii) subsequent formation of the clusters by coalescence of single nucleons. While both approaches have been successfully applied in the past it has not yet been clarified which of the two mechanisms dominates the cluster production. We propose to use recently developed event-by-event techniques to study particle multiplicity fluctuations on nuclear clusters and employ this analysis to the deuteron number fluctuations to disentangle the two production mechanisms. We argue that for a grand canonical cluster formation, the cluster fluctuations will follow Poisson distribution, while for the coalescence scenario, the fluctuations will strongly deviate from the Poisson expectation. We estimate the effect to be 10% for the variance and up to a factor of 5 for the kurtosis of the deuteron number multiplicity distribution. Our prediction can be tested in the beam energy scan program at RHIC as well as experiments at the FAIR and NICA facilities.

   ↳ nucl-thnucl-exPRC(2016)·31 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.