Nuclear Theory·nucl-th

Tuesday·June 9, 2015

12 papers—8 primary·4 cross-listed

09
Positive and negative parity hyperons in nuclear medium
K. Azizi🇹🇷 · N. Er🇹🇷 · H. Sundu🇹🇷
The effects of nuclear medium on the residue, mass and self energy of the positive and negative parity $Σ$ , $Λ$ and $Ξ$ hyperons are investigated using the QCD sum rule method. In the calculations, the general interpolating currents of hyperons with an arbitrary mixing parameter are used. We compare the results obtained in medium with those of the vacuum and calculate the shifts in the corresponding parameters. It is found that the shifts on the residues in nuclear matter are over all positive for both the positive and negative parity hyperons, except for the positive parity $Σ$ hyperon that the shift is negative. The shifts on the masses of these baryons are obtained to be negative. The shifts on the residues and masses of negative parity states are large compared to those of positive parities. The maximum shift belongs to the residue of the negative parity $Λ$ hyperon. The vector self-energies gained by the positive parity baryons are large compared to the negative parities' vector self-energies. The maximum value of the vector self-energy belongs to the positive parity $Σ$ hyperon. The numerical values are compared with the existing predictions in the literature.
↳ hep-phnucl-thPRD(2015)·11 citations
10
Colliding shock waves and hydrodynamics in small systems
Paul M. Chesler🇺🇸
Using numerical holography, we study the collision of a planar sheet of energy with a bounded localized distribution of energy. The collision, which mimics proton-nucleus collisions, produces a localized lump of debris with transverse size $R \sim 1/ T_{eff}$ with $T_{eff}$ the effective temperature, and has large gradients and large transverse flow. Nevertheless, the postcollision evolution is well described by viscous hydrodynamics. Our results bolster the notion that debris produced in proton-nucleus collisions may be modeled using hydrodynamics.
↳ hep-thgr-qchep-phnucl-thPRL(2015)·81 citations
11
New structures in the proton-antiproton system
I.T. Lorenz🇩🇪 · H.-W. Hammer🇩🇪 · U.-G. Meißner🇩🇪
In the most recent measurements of the reaction $e^{+} e^{-} \to p p ˉ$ by the BABAR collaboration, new structures have been found with unknown origin. We examine a possible relation of the most distinct peak to the recently observed $Φ (2170)$ . Alternatively, we analyse possible explanations due to the nucleon $Δ ˉ$ and $Δ Δ ˉ$ thresholds. The latter could explain a periodicity found in the data.
↳ hep-phhep-exnucl-thPRD(2015)·56 citations
12
The $m$ 'bottom-up parton system with two momentum scales
Vladimir Khachatryan🇺🇸 · Mickey Chiu🇺🇸 · Thomas K. Hemmick🇺🇸
One possible evolutionary scenario of the dense gluon system produced in an ultrarelativistic heavy ion collision is the bottom-up thermalization scenario, which describes the dynamics of the system shortly after the collision via the decay of originally produced hard gluons to soft ones through QCD branching processes. The soft gluons form a thermal bath that subsequently reaches thermalization and/or equilibration. There is a scaling solution to the bottom-up problem that interpolates between its early stage, which has a highly anisotropic gluon distribution, and its final stage of equilibration which occurs later. Such a solution depends on a single parameter, the so called momentum asymmetry parameter $δ$ . With this scaling solution, the bottom-up scenario gets modified and the evolving parton system, referred to as the $m$ 'bottom-up parton system throughout this paper, is described by this modification. The time evolution of the system in the original bottom-up ansatz is driven by the saturation scale, $Q_{s}$ . However, for the $m$ 'bottom-up we generalize the ansatz of the evolution by introducing two additional momentum scales, which give a thermalization time and temperature of the soft gluon bath somewhat different from those obtained when the $m$ 'bottom-up matches onto the final stage of the original bottom-up scenario.
↳ hep-phnucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Positive and negative parity hyperons in nuclear medium

Colliding shock waves and hydrodynamics in small systems

New structures in the proton-antiproton system

The m'bottom-up parton system with two momentum scales

Affiliations

The $m$ 'bottom-up parton system with two momentum scales