Mon·Dec 2, 2019Monday·December 2, 2019

1. 01*

   Freed-Isobar Analysis of Light Mesons at COMPASS

   Fabian Krinner (for the COMPASS Collaboration)🇩🇪

   Modern hadron-spectroscopy experiments such as COMPASS collect data samples of unprecedented size, so that novel analysis techniques become possible and necessary. One such technique is the freed-isobar partial-wave analysis (PWA). In this approach, fixed parametrizations for the amplitudes of intermediate states commonly modeled using Breit-Wigner shapes are replaced by sets of step-like functions that are determined from the data. This approach not only reduces the model dependence of partial-wave analyses, but also allows us to study the amplitudes of the intermediate states and their dependence on the parent system. We will also present results of a freed-isobar PWA performed on the large data set on diffractive production of three charged pions collected by the COMPASS experiment, which consists of $46\times 10^6$ exclusive events. We will focus on results for the wave with spin-exotic quantum numbers $J^{PC}=1^{-+}$, in particular on its decay into $\rho (770)\pi$. Here, the freed-isobar PWA method provides insight into the interplay of three- and two-particle dynamics and confirms the decay of the spin-exotic ${\pi }_1(1600)$ resonance to $\rho (770)\pi$ in a model-independent way.

   ↳ hep-exnucl-ex2 citations
2. 02*

   Charmed excited baryons with heavy-quark spin symmetry

   L. Tolos🇩🇪 · J. Nieves🇪🇸 · R. Pavao🇪🇸

   Recently five ${\Omega }_c$ excited states have been reported by the LHCb Collaboration, four of them corroborated by Belle. The Belle Collaboration has also discovered in 2017 one excited ${\Xi }_c$ with mass of 2930 MeV. In view of these recent detections, we analyze the possible molecular description of these states, using a unitarized baryon-meson model that incorporates both chiral and heavy-quark spin symmetries in a consistent manner. We pay a special attention to the renormalization procedure, so as to determine the robustness of our predictions. Within our model, we generate dynamically several ${\Omega }_c$ and ${\Xi }_c$ states. We find that, at least, three of our ${\Omega }_c$ states can be identified with the experimental ones and have spin-parity $J=1/2^{-}$ or $J=3/2^{-}$. Moreover, we find a plausible molecular description of not only the ${\Xi }_c(2930)$ state, but also ${\Xi }_c(2790)$, ${\Xi }_c(2815)$ and ${\Xi }_c(2970)$, reported in the PDG. Interestingly, we determine that ${\Xi }_c(2930)$ and ${\Xi }_c(2970)$ are heavy-quark spin partners with $J=1/2^{-}$ and $J=3/2^{-}$, respectively, while obtaining that ${\Xi }_c(2930)$, ${\Omega }_c(3090)$ or the ${\Omega }_c(3119)$, and ${\Sigma }_c(2800)$ would belong to the same SU(3) multiplet.

   ↳ hep-phhep-exnucl-exnucl-th0 citations
3. 03*

   Intermittency study of charged particles generated in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}\text{= 2.76 TeV}$ using EPOS3

   Ramni Gupta🇮🇳 · Salman Khurshid Malik🇮🇳

   Charged particle multiplicity fluctuations in Pb-Pb collisions are studied for the central events generated using EPOS3 (hydro and hydro+cascade) at $\sqrt{s_{\mathrm{NN}}}\text{ = 2.76 TeV}$. Intermittency analysis is performed in the mid-rapidity region in two-dimensional ($\eta$, $\varphi$) phase space within the narrow transverse momentum (p_\rm{{T}}) bins in the low p_\rm{{T}}~region (p_\rm{{T}}~\leq~1.0~GeV/\textit{c}). Power-law scaling of the normalized factorial moments with the number of bins is not observed to be significant in any of the p_\rm{{T}}-bin. Scaling exponent $\nu$, deduced for a few p_\rm{{T}} bins is greater than that of the value 1.304, predicted for the second order phase-transition by the Ginzburg-Landau theory. The link in the notions of fractality is also studied. Fractal dimensions, $D_q$ are observed to decrease with the order of the moment $q$ suggesting the multifractal nature of the particle generation in EPOS3.

   ↳ hep-exnucl-exAdv.High Energy Phys.(2020)·15 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.