Boundary and Coulomb effects on boson systems in high-energy heavy-ion collisions

Abstract

The boundary of a boson system plays an important role in determining the momentum distribution of the bosons. For a boson system with a cylindrical boundary, the momentum distribution is enhanced at high transverse momenta but suppressed at low transverse momenta, relative to a Bose-Einstein distribution. The boundary e ects on systems of massless gluons and massive pions are studied. For gluons in a quark-gluon plasma, the presence of the boundary may modify the signals for the quark-gluon plasma. For pions in a pion system in heavy-ion collisions, Coulomb nal-state interactions with the nuclear participants in the vicinity of the central rapidity region further modify the momentum distribution at low transverse momenta. By including both the boundary e ect and the Coulomb nal-state interactions we are able to account for the behavior of the transverse momentum spectrum observed in many heavy-ion experiments, notably at low transverse momenta. PACS Number(s): 13.85. 13.85.Ni, 12.38.Mh (Submitted to The Phys. Rev. C)Typeset using REVT E X 3.0 E-Mail: mostafa@orph01.phy.ornl.gov (gadalhaq@frcu.eun.eg, after June, 1995).y E-Mail: wong@orph01.phy.ornl.gov.

Small size boundary effects on two-pion interferometry

“…We should notice that this result coincides with the one obtained in Ref. [7,9], and is opposite to the results from Ref. [8,11].…”

“…As we shall see later, in agreement with results of Ref. [7,9,10], a depletion in the low momentum region is observed instead. This apparent discrepancy may be explained by both the form chosen for the density matrix in Ref.…”

“…The above formula coincides with the one employed in Ref. [9] for expressing the single-pion distribution.…”

Momentum kick model description of the near-side ridge and jet quenching

“…Transverse distributions of this type can be described by replacing the denominator m 2 + p 2 ti with m 2 d + p 2 ti where m d can be adjusted to lead to the correct ridge yield at p t ∼ 1 GeV. The extracted transverse momentum distribution may provide useful information to study the transverse radius of the deconfined parton medium [54,55].…”

“…If the partons arise from a deconfined medium with a finite transverse boundary, then the transverse parton momentum distribution at small p t will be flattened from an exponential distribution, as shown in Figs. 1 and 2 of [54]. Transverse distributions of this type can be described by replacing the denominator m 2 + p 2 ti with m 2 d + p 2 ti where m d can be adjusted to lead to the correct ridge yield at p t ∼ 1 GeV.…”