Speaker
Cheuk-Yin Wong
(Oak Ridge National Laboratory)
Description
The initial conditions in high-energy pp collisions can be well
examined from the momentum distributions of both jets and hadrons in
these collisions, as they provide relevant information on the
collision mechanism and the initial properties of the produced medium.
It was found recently that in pp collisions at the LHC, the hadron
transverse momentum distributions at central rapidity spanning 14
decades of magnitude over the pT domain from the lowest of ~0.5 GeV/c
to the highest of ~200 GeV/c can be adequately described by a single
Tsallis distribution with only three apparent degrees of freedom [1].
The simplicity of the pT spectrum over such a large pT domain, and the
subsequent hard-scattering model analysis of the jet and hadron
momentum distributions suggest indirectly that a single mechanism, the
hard-scattering between partons, dominates over almost the whole pT
domain in these high-energy collisions [2]. Direct evidence of such a
dominance is further provided by the experimental observation of the
signature for the hard-scattering process, as indicated by the
two-particle angular correlations with minimum-pT-biased hadrons [3].
One is led naturally to the initial conditions that in
high-multiplicity events in high-energy pp collisions, parallel
hard-scattering collisions of partons generate both the jet and the
bulk medium whose subsequent collisions lead to the angular
correlations of the near-side ridge, as described in the momentum kick
model for such correlations [4-7].
[1] C.Y.Wong , G.Wilk, {Tsallis fits to pT spectra for pp collisions at
LHC}, Acta.Phys.Pol. B43,247(2012).
[2] C.Y.Wong , G.Wilk, {Tsallis fits to pT spectra and multiple hard
scattering in pp Collisions at the LHC}, Phys.Rev.D87,114007(2013).
[3] C.Y.Wong,G.Wilk,L.Cirto,C.Tsallis, {From QCD-based hard-scattering
to nonextensive statistical mechanical descriptions of transverse
momentum spectra in high-energy pp and p-pbar collisions},
Phys.Rev.D91,114027(2015).
[4] C.Y.Wong, {The Momentum Kick Model Description of the Near-Side
Ridge and Jet Quenching}, Phys.Rev.C78:064905,(2008).
[5] C.Y.Wong, {Exploring Early Parton Momentum Distribution with the
Ridge from the Near-Side Jet}, J.Phys.G35:104085,(2008).
[6] C.Y.Wong, {Parton Momentum Distribution at the Moment of Jet-Parton
Collision}, Chin. Phys. Lett. 25, 3936 (2008).
[7] C.Y.Wong, {Momentum-Kick model description of the ridge in
(Delta-phi)-(Delta eta) correlation in pp collisions at 7 TeV},
Phys.Rev.C84:024901,(2011).
Primary author
Cheuk-Yin Wong
(Oak Ridge National Laboratory)
