Nuclear Theory·nucl-th

Monday·April 4, 2016

9 papers—6 primary·3 cross-listed

01
Correlations and fluctuations of pions at the LHC
Viktor V. Begun🇵🇱
The intriguing possibility of Bose-Einstein condensation of pions at the LHC is examined with the use of higher order moments of the multiplicity distribution. The scaled variance, skewness and kurtosis are calculated for the pion system. The obtained results show that the normalized kurtosis has a significant increase for the case of the pion condensation.
nucl-thhep-exhep-phnucl-exActa Phys.Polon.Supp.(2016)·1 citation
02
Effects of Nonlocality on Transfer Reactions
Luke J. Titus
We solved the nonlocal scattering and bound state equations using the Perey-Buck type interaction, and compared to local equivalent calculations. Using the distorted wave Born approximation we construct the T-matrix for (p,d) transfer on 17O, 41Ca, 49Ca, 127Sn, 133Sn, and 209Pb at 20 and 50 MeV. Additionally we studied (p,d) reactions on 40Ca using the the nonlocal dispersive optical model. We have also included nonlocality consistently into the adiabatic distorted wave approximation and have investigated the effects of nonlocality on on (d,p) transfer reactions for deuterons impinged on 16O, 40Ca, 48Ca, 126Sn, 132Sn, 208Pb at 10, 20, and 50 MeV. We found that for bound states the Perry corrected wave functions resulting from the local equation agreed well with that from the nonlocal equation in the interior region, but discrepancies were found in the surface and peripheral regions. Overall, the Perey correction factor was adequate for scattering states, with the exception for a few partial waves. Nonlocality in the proton scattering state reduced the amplitude of the wave function in the nuclear interior. The same was seen for nonlocality in the deuteron scattering state, but the wave function was also shifted outward. In distorted wave Born approximation studies of (p,d) reactions using the Perey-Buck potential, we found that transfer distributions at the first peak differed by 15-35% as compared to the distribution resulting from local potentials. When using the dispersive optical model, this discrepancies grew to 30-50%. When nonlocality was included consistently within the adiabatic distorted wave approximation, the disagreement was found to be ~40%. This highlights the necessity to pursue reaction formalisms that include nonlocality exactly.
nucl-th1 citation
03
Finite size effects on the phase diagram of the thermodynamical cluster model
S.Mallik🇮🇳 · F. Gulminelli🇫🇷 · G. Chaudhuri🇮🇳
The thermodynamical cluster model is known to present a first-order liquid-gas phase transition in the idealized case of an uncharged, infinitely extended medium. However, in most practical applications of this model, the system is finite and charged. In this paper we study how the phase diagram is modified by finite size and Coulomb effects. We show that the thermodynamic anomalies which are associated to the finite system counterpart of first order phase transitions, are correctly reproduced by this effective model. However, approximations in the calculation of the grandcanonical partition sum prevent obtaining the exact mapping between statistical ensembles which should be associated to finite systems. The ensemble inequivalence associated to the transition persists in the presence of Coulomb, but the phase diagram is deeply modified with respect to the simple liquid-gas phase transition characteristic of the neutral system.
nucl-thPRC(2015)·9 citations
04
Effect of particle fluctuation on isoscaling and isobaric yield ratio of nuclear multifragmentation
S. Mallik · G. Chaudhuri
Isoscaling and isobaric yield ratio parameters are compared from canonical and grand canonical ensembles when applied to multifragmentation of finite nuclei. Source dependence of isoscaling parameters and source and isospin dependence of isobaric yield ratio parameters are examined in the framework of the canonical and the grand canonical models. It is found that as the nucleus fragments more, results from both the ensembles converge and observables calculated from the canonical ensemble coincide more with those obtained from the formulae derived using the grand canonical ensemble.
nucl-thnucl-exPLB(2013)·17 citations
05
Predictions on the alpha decay half lives of Superheavy nuclei with Z = 113 in the range 255 l.e. A l.e. 314
K. P. Santhosh · A. Augustine · C. Nithya · B. Priyanka
An intense study of the alpha decay properties of the isotopes of superheavy element Z=113 have been performed within the Coulomb and proximity potential model for deformed nuclei (CPPMDN) within the wide range 255 l.e. A l.e. 314. The predicted alpha decay half lives of $^{278}$ 113 and $^{282}$ 113 and the alpha half lives of their decay products are in good agreement with the experimental data. 6{\alpha) chains and 4{\alpha} chains predicted respectively for $^{278}$ 113 and $^{282}$ 113 are in agreement with the experimental observation. Our study shows that the isotopes in the mass range 278 l.e. A l.e. 286 will survive fission and can be synthesized and detected in the laboratory via alpha decay. In our study, we have predicted 6{\alpha} chains from $^{279}$ 113, 4{\alpha} chains from $^{286}$ 113, 3{\alpha} chains from $^{280, 281, 283}$ 113, 2{\alpha} chains from $^{284}$ 113 and 1{\alpha} chain from $^{285}$ 113. We hope that these predictions will be a guideline for future experimental investigations.
nucl-thNPA(2016)·17 citations
06
Closed expression for the pair vibrational correlation energy of a uniform distribution of single-nucleon levels
K. Neergård
A closed expression is derived for the pair vibrational correlation energy generated in the random phase approximation by the isovector pairing force in the case when Kramers and charge degenerate single-nucleon levels are uniformly distributed in an interval. The expression is used to analyze the spectral density of pair vibrational frequencies relative to that of two-quasinucleon energies. Applications to the analysis of the symmetry energy of the isovector pairing model and to a Strutinskij renormalization of this model are discussed.
nucl-thPRC(2016)·3 citations
07
Mechanisms of the isospin-breaking decay $f_{1} (1285) \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$
N.N. Achasov🇷🇺 · A.A. Kozhevnikov🇷🇺 · G.N. Shestakov🇷🇺
Estimated are the contributions of the following mechanisms responsible for the decay $f_{1} (1285) \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ : 1) the contribution of the $a_{0}^{0} (980) - f_{0} (980)$ mixing, $f_{1} (1285) \to a_{0} (980) π^{0} \to (K^{+} K^{-} + K^{0} K ˉ^{0}) π^{0} \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ , 2) the contribution of the transition $f_{1} (1285) \to (K^{+} K^{-} + K^{0} K ˉ^{0}) π^{0} \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ , arising due to the pointlike decay $f_{1} (1285) \to K K ˉ π^{0}$ , 3) the contribution of the transition $f_{1} (1285) \to (K^{*} K ˉ + K ˉ^{*} K) \to (K^{+} K^{-} + K^{0} K ˉ^{0}) π^{0} \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ , where $K^{*} = K^{*} (892)$ , and 4) the contribution of the transition $f_{1} (1285) \to (K_{0}^{*} K ˉ + K ˉ_{0}^{*} K) \to (K^{+} K^{-} + K^{0} K ˉ^{0}) π^{0} \to f_{0} (980) \to π^{+} π^{-} π^{0}$ , where $K_{0}^{*} = K_{0}^{*} (800)$ (or $κ$ ) and $K_{0}^{*} (1430)$ . These mechanisms break the conservation of the isospin due to the nonzero mass difference of the $K^{+}$ and $K^{0}$ mesons. They result in the appearance of the narrow resonance structure in the $π^{+} π^{-}$ mass spectrum in the region of the $K K ˉ$ thresholds, with the width $\approx 2 m_{K^{0}} - 2 m_{K^{+}} \approx 8$ MeV. The observation of such a structure in experiment is the direct indication on the $K K ˉ$ loop mechanism of the breaking of the isotopic invariance. We point out that existing data should be more precise, and it is difficult to explain them using the single specific mechanism from those listed above. Taking the decay $f_{1} (1285) \to f_{0} (980) π^{0} \to π^{+} π^{-} π^{0}$ as the example, we discuss the general approach to the description of the $K K ˉ$ loop mechanism of the breaking of isotopic invariance.
↳ hep-phhep-exnucl-thPRD(2016)·22 citations
08
Single inclusive forward hadron production at next-to-leading order
B. Ducloué🇫🇮 · T. Lappi🇫🇮 · Y. Zhu🇫🇮
We discuss single inclusive hadron production from a high energy quark scattering off a strong target color field in the Color Glass Condensate formalism. Recent calculations of this process at the next-to-leading order accuracy have led to negative cross sections at large transverse momenta. We identify the origin of this problem as an oversubtraction of the rapidity divergence into the Balitsky-Kovchegov evolution equation for the target. We propose a new way to implement the kinematical restriction on the emitted gluons to overcome this difficulty.
↳ hep-phnucl-thPRD(2016)·70 citations
09
Initial State Quantum Fluctuations in the Little Bang
Francois Gelis🇫🇷 · Bjoern Schenke🇺🇸
We review recent developments in the ab-initio theoretical description of the initial state in heavy-ion collisions. We emphasize the importance of fluctuations, both for the phenomenological description of experimental data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), and the theoretical understanding of the non-equilibrium early time dynamics and thermalization of the medium.
↳ hep-phnucl-thAnn.Rev.Nucl.Part.Sci.(2016)·30 citations

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