Tue·Apr 5, 2016Tuesday·April 5, 2016

1. 01*

   Evaluation of the forward Compton scattering off protons: II. Spin-dependent amplitude and observables

   Oleksii Gryniuk🇩🇪 · Franziska Hagelstein🇩🇪 · Vladimir Pascalutsa (JGU Mainz)🇩🇪

   The forward Compton scattering off the proton is determined by substituting the empirical total photoabsorption cross sections into dispersive sum rules. In addition to the spin-independent amplitude evaluated previously [Phys. Rev. D 92, 074031 (2015)], we obtain the spin-dependent amplitude over a broad energy range. The two amplitudes contain all the information about this process, and we, hence, can reconstruct the nonvanishing observables of the proton Compton scattering in the forward kinematics. The results are compared with predictions of chiral perturbation theory where available. The low-energy expansion of the spin-dependent Compton scattering amplitude yields the Gerasimov-Drell-Hearn (GDH) sum rule and relations for the forward spin polarizabilities (FSPs) of the proton. Our evaluation provides an empirical verification of the GDH sum rule for the proton, and yields empirical values of the proton FSPs. For the GDH integral, we obtain $204.5(21.4)$ $\mu$b, in agreement with the sum rule prediction: $204.784481(4)$ $\mu$b. For the FSPs, we obtain: ${\gamma }_0=-92.9(10.5)\times 10^{-6}$ fm${}^4$, and $\overline{{\gamma }_0}=48.4(8.2)\times 10^{-6}$ fm${}^6$, improving on the accuracy of previous evaluations.

   ↳ nucl-thhep-phnucl-exPRD(2016)·22 citations
2. 02*

   Liquid gas phase transition in hypernuclei

   S. Mallik🇮🇳 · G. Chaudhuri🇮🇳

   The fragmentation of excited hypernuclear system formed in heavy ion collisions has been described by the canonical thermodynamical model extended to three component systems. The multiplicity distribution of the fragments has been analyzed in detail and it has been observed that the hyperons have the tendency to get attached to the heavier fragments. Another important observation is the phase coexistence of the hyperons, a phenomenon which is linked to liquid gas phase transition in strange matter.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2015)·6 citations
3. 03*

   Effect of hyperons on phase coexistence in strange matter

   P. Das🇮🇳 · S. Mallik🇮🇳 · G. Chaudhuri🇮🇳

   The study of liquid gas phase transition in fragmentation of nuclei in heavy ion collisions has been extended to the strangeness sector using the statistical model for multifragmentation. Helmholtz's free energy, specific heat and few other thermodynamic observables have been analyzed in order to examine the occurence of phase transition in the strange matter. The bimodal behaviour of the largest cluster formed in fragmentation also strongly indicates coexistence of both the phases. The presence of hyperons strengthens the signals and also shifts the transition temperature to lower values.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2017)·2 citations
4. 04*

   Ferro-deformation and shape phase transitions over the nuclear chart: 50 < protons (Z) < 82 and 50 < neutrons (N) < 126

   Chang-Bum Moon

   We study a global nuclear structure in the framework of experimental observables. With the aid of large nuclear structure data at the national nuclear data center, NNDC, we present the distinctive systematic patterns emerged in the first 2+ excited energies, E(2+) and their energy ratios to the first 4+ levels, R = E(4+)/E(2+), in the even-even nuclei, over 50 < Z < 82 for protons, and 50 < N < 126 for neutrons. We introduce the so-called pseudo-shell configurations from the subshells mixture in order to explain a semi-double shell closure, a shape phase transition, and a reinforced deformation. It is found that the reinforced deformation arises when Z = 64 or 66 correlates with N = 90 and reaches its maximum, indicating R = 3.3. Such a saturated reinforced deformation spans over Z = 58 to 72 and N = 100 to 106 as showing its center at Z = 64 or 66 and at N = 102 or 104. We define this reinforced deformation 'a ferro-deformation' like a ferro-magnetism in condensed matter physics. The shape coexistence would be expected to occur, such as a ferro-deformation, with a strong rotational mode, and a near spherical shape, with a vibrational mode, at the critical points of Z = 64 or 66, with N = 88 and 90; 150Sm and 152Sm, 152Gd and 154Gd, and 154Dy and 156Dy. We suggest that a super-deformation, which can be formed at high-lying excited states in a moderate deformed nucleus, would correspond to the ferro-deformation at N = 88 for the nuclei; Sm, Gd, and Dy. We argue that the ferro-deformation can be closely associated with a strong spin-orbital interaction between neutrons and protons in the spin-orbit doublet, h9/2-h11/2, leading to the critical points at Z, N = 64, 104.

   ↳ nucl-thnucl-ex5 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.