Topical Seminar on Frontier of Particle Physics 2004: QCD and Light Hadrons Lecture 2 Wei Zhu East...
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![Page 1: Topical Seminar on Frontier of Particle Physics 2004: QCD and Light Hadrons Lecture 2 Wei Zhu East China Normal University.](https://reader036.fdocuments.us/reader036/viewer/2022062311/5a4d1b8a7f8b9ab0599be9aa/html5/thumbnails/1.jpg)
Topical Seminar on Frontier of Particle Physics 2004: QCD and Light Hadrons Lecture 2 Wei ZhuEast China Normal University
![Page 2: Topical Seminar on Frontier of Particle Physics 2004: QCD and Light Hadrons Lecture 2 Wei Zhu East China Normal University.](https://reader036.fdocuments.us/reader036/viewer/2022062311/5a4d1b8a7f8b9ab0599be9aa/html5/thumbnails/2.jpg)
Outline of Lecture Two
BFKL Equations
DGLAP Equations
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1. A simplest derivation of DGLAP equations
Bjorken Frame, A+=0
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2. A simplest derivation of BFKL equationsBjorken frame
The virtual probe has almost zero-energy and zero-longitudinal momentum, so that the momentum of the probe is mainly transverse to the nucleon direction.
Resolution of probe
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Cold spots
Size of cold spot
Resolution of probeImpulse approximation
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At small x and fixed Q2, beyond impulse approximation
DGLAP amplitude (for gluon)
Impulse approximation
NQ xx
What will happen?
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QCD, Parton Model, Tree Level+ +
++
+ +……2
a b c
d e
f Beyond impulse approximation
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DGLAP
BFKL
Modified DGLAP
A New Equation?
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BFKL equation
We separated out the probe vertex using the W -W approximation, where the transverse momenta of initial gluons are unvanished.
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Taking the leading logarithmic (1/x) approximation, one can get the total amplitude
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Impact Space (A. H. Mueller)
Evolution Kernel
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Note that z1 >>z2 at the LLA(1/x), we insert δ(z1 -1) and obtain the evolution equation
where y = ln(1/z) and
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Contributions from virtual diagrams
Using the TOPT cutting rule
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Integrated distribution
Unintegrated distribution
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Small x Physics