The Δ(1232) at RHIC

Abstract

Abstract. We investigate properties of the ∆(1232) and nucleon spectral functions at finite temperature and baryon density within a hadronic model. The medium modifications of the ∆ consist of a renormalization of its pion-nucleon cloud and resonant π∆ scattering. Underlying coupling constants and form factors are determined by the elastic πN scattering phase shift in the isobar channel, as well as empirical partial decay widths of excited baryon resonances. For cold nuclear matter the model provides reasonable agreement with photoabsorption data on nuclei in the ∆-resonance region. In hot hadronic matter typical for late stages of central Au-Au collisions at RHIC we find the ∆-spectral function to be broadened by ∼65 MeV together with a slight upward mass shift of 5-10 MeV, in qualitative agreement with preliminary data from the STAR collaboration.

Probing the properties of dense partonic matter at RHIC

“…In addition, the data may require a strong energy loss of beauty in the medium. This leads to a recent suggestion that the main energy loss mechanism is not gluon radiation, but elastic scattering [ 10,11].…”

“…In turn, charm quark flow would indicate high parton density and strong coupling in the matter. The strength of the flow can be reproduced either by resonance-like states [ 10] or a large cross section of c-quarks (σ ≃ 10 mb) [ 15] in the dense medium. If these models are correct, the charm flow data can be taken as evidence for strongly coupled QGP.…”

A hadronic transport analysis on the Δ mass in Au + Au reactions at 1.23 AGeV

“…In this region, modifications to the spectral functions, often called in‐medium effects, of the hadrons are common due to the large baryochemical potential. Such in‐medium effects have been extensively studied at Relativistic Heavy Ion Collider (Bleicher & Aichelin ; Broniowski et al ; Geurts ; Kolb & Prakash ; Makek ; Torrieri & Rafelski ) energies and Super Proton Synchrotron (Arnaldi et al ; Bratkovskaya & Ko ; Damjanovic et al ; Endres et al ; van Hees & Rapp ); for the latest results from the Large Hadron Collider, we refer to (Acharya et al ); Albuquerque ); Tripathy ). While in the past, the ρ meson and its decay into di‐leptons was the most studied resonance in relation to in‐medium effects, the high acceptance di‐electron spektrometer (HADES) experiment has not yet reported on a hadronic decay of the ρ meson.…”