UNINTEGRATED GLUON DISTRIBUTION AND GLUON SATURATION IN P-P AT LHC
A prediction of unintegrated parton distribution
-
Upload
jerome-grimes -
Category
Documents
-
view
34 -
download
4
description
Transcript of A prediction of unintegrated parton distribution
1
A prediction of unintegrated parton
distributionRuan Jianhong Zhu Wei
East China Normal University
2
outline
Introduction
The models
Our scheme
Conclusion
3
1 Introduction
① The integrated parton distributuion ),( 2xxa
evolution according to DGLAP equation, input parton distribution such as
GRV,MRST,CTEQ… can be used to describe inclusive processes
well decided by the global fit of structure function F2
:),( 2xxa ),( 2xxv),( 2xxs),( 2xxg
4
② the unintegrated parton distribution ),,( 22 tkxf
For less inclusive processes, the distributions unintegrated over the tranverse momentum have to be considerd.
),(),,( 2
0
222
22
xxakxfk
dkta
t
t
5
2 The models① CCFM evolution equation:
The unintegrated gluon distribution satisfies the CCFM evolution equation based on angular ordering.
The solution of the CCFM equation has only proved practically with Monte Carlo generators.
The interactions among initial partons are neglected in the CCFM equation.
6
② Golec-Biernat-Wusthoff gluon distribution
Based on the parametrization of the dipole-nucleon cross section with parameters fitted to the HERA data
7
③ Kharzeev-Levin gluon distribution
based on the idea of gluon saturation, the gluon distribution is parametrized.
It was claimed that the gluon distribution leads to a good description of the recent RHIC rapidity distributions.
8
Kimber, Martin and Ryskin proposed that the two scale UPDFs can be derived from the single-scale unintegrated distribution, and its dependence on the second scale μ is introduced by using the Sudakov factor.
④ KMR scheme
9
3 Our method: KMR scheme
MD_DGLAP
equation
10
11
12
the initial quark and gluon densities (GRV-like)
13
14
15
16
our result
The unintegrated gluondensity in proton at μ=10 GeV
17
The unintegrated gluondistributions in Pb(A=208)
18
Comparison of our predicted (RZ)-gluon(solid curves) with other models
19
Published in physics review c 80,045209(2009)
20
① Two component model
Ⅰcentral region
Ⅱ fragmentation region
gg →g mechanism
quark recombination model
Particle multiplicities and limiting fragmentation
21
),)2
(,(),)2
(,()(1
1
4 2,
2,,2
2,
2,,1,
22,
2
,2
gtgtgtp
ggtgtgtp
gsgtgtc
c
gt
Ipp
pqp
xFpqp
xFqdpN
N
pdyd
d
Ⅰcentral region
Ⅱ fragmentation region
x
tptpt
IIpp
in
pxxsxxpxvxdxx
x
dxdp
d0
211
21112
),())(1(2
1),(
16
1
d
dN
d
dN
d
dN IIpp
Ipppp
22
Proton-proton collisions
ssd
dN pp 20 ln023.0ln25.05.2
23
24
25
26
② Fragmentation limiting
beamy '
)/ln( Nbeam msy
27
28
29
5 Conclusion:
① we predict the unintegrated parton distributions in proton and nucleus by using the KMR scheme incorporating the shadowing and antishadowing corrections②We find that the suppression of the unintegrated gluon distribution when kt→ 0 arises from the valence-like input rather than the nonlinear saturation effect, although the nonlinear shadowing effect is obvious.③We use two complementary production mechanisms: hard gluon-gluon fusion in the central rapidity region and soft quark recombination in the fragmentation region to study the particle multiplicity distributions in hadron-hadron collisions at high energies.
④We find that the limiting fragmentation hypothesis, which generally appear in present data of hadron collisions is partly violated if the observations are across over a wide range between the RHIC-LHC energies.
30
Thank You!