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Investigations into the BFKL mechanism with a running QCD coupling

Andersson, Bo LU ; Gustafson, Gösta LU and Kharraziha, Hamid (1998) In Physical Review D (Particles and Fields) 57(9). p.5543-5554
Abstract
We present approximations of varying degree of sophistication to the integral equations for the (gluon) structure functions of a hadron ("the partonic flux factor") in a model valid in the leading log approximation with a running coupling constant. The results are all of the BFKL type, i.e., a power in the Bjorken variable x(B)(-lambda) with the parameter lambda determined from the size alpha(0) of the "effective" running coupling <(alpha)over bar>=3 alpha(s)/pi =alpha(0)/ln(k(perpendicular to)(2)) and varying depending upon the treatment of the transverse momentum pole, we also consider the implications for the transverse momentum (k(perpendicular to)) fluctuations along the emission chains and we obtain an exponential falloff in... (More)
We present approximations of varying degree of sophistication to the integral equations for the (gluon) structure functions of a hadron ("the partonic flux factor") in a model valid in the leading log approximation with a running coupling constant. The results are all of the BFKL type, i.e., a power in the Bjorken variable x(B)(-lambda) with the parameter lambda determined from the size alpha(0) of the "effective" running coupling <(alpha)over bar>=3 alpha(s)/pi =alpha(0)/ln(k(perpendicular to)(2)) and varying depending upon the treatment of the transverse momentum pole, we also consider the implications for the transverse momentum (k(perpendicular to)) fluctuations along the emission chains and we obtain an exponential falloff in the relevant kappa=ln(k(perpendicular to)(2)) variable, i.e., an inverse power (k(perpendicular to)(2))(-(2+lambda)) with the same parameter lambda. This is different from the BFKL result for a fixed coupling, where the distributions are Gaussian in the kappa variable with a width as in a Brownian motion determined by "the length" of the emission chains, i.e., In(1/x(B)). The results are verified by a realistic Monte Carlo simulation and we provide a simple physics motivation for the change. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review D (Particles and Fields)
volume
57
issue
9
pages
5543 - 5554
publisher
American Physical Society
external identifiers
  • scopus:0001663240
ISSN
0556-2821
DOI
10.1103/PhysRevD.57.5543
language
English
LU publication?
yes
id
561f6048-9d73-45d9-bf43-2d36ca2c7ac1 (old id 33704)
alternative location
http://link.aps.org/abstract/PRD/v57/p5543
date added to LUP
2008-01-14 14:51:35
date last changed
2017-01-01 06:45:47
@article{561f6048-9d73-45d9-bf43-2d36ca2c7ac1,
  abstract     = {We present approximations of varying degree of sophistication to the integral equations for the (gluon) structure functions of a hadron ("the partonic flux factor") in a model valid in the leading log approximation with a running coupling constant. The results are all of the BFKL type, i.e., a power in the Bjorken variable x(B)(-lambda) with the parameter lambda determined from the size alpha(0) of the "effective" running coupling &lt;(alpha)over bar&gt;=3 alpha(s)/pi =alpha(0)/ln(k(perpendicular to)(2)) and varying depending upon the treatment of the transverse momentum pole, we also consider the implications for the transverse momentum (k(perpendicular to)) fluctuations along the emission chains and we obtain an exponential falloff in the relevant kappa=ln(k(perpendicular to)(2)) variable, i.e., an inverse power (k(perpendicular to)(2))(-(2+lambda)) with the same parameter lambda. This is different from the BFKL result for a fixed coupling, where the distributions are Gaussian in the kappa variable with a width as in a Brownian motion determined by "the length" of the emission chains, i.e., In(1/x(B)). The results are verified by a realistic Monte Carlo simulation and we provide a simple physics motivation for the change.},
  author       = {Andersson, Bo and Gustafson, Gösta and Kharraziha, Hamid},
  issn         = {0556-2821},
  language     = {eng},
  number       = {9},
  pages        = {5543--5554},
  publisher    = {American Physical Society},
  series       = {Physical Review D (Particles and Fields)},
  title        = {Investigations into the BFKL mechanism with a running QCD coupling},
  url          = {http://dx.doi.org/10.1103/PhysRevD.57.5543},
  volume       = {57},
  year         = {1998},
}