All Questions
Tagged with quantum-chromodynamics scattering
32
questions
19
votes
2
answers
3k
views
Why Cronin Effect Happens?
I'm looking for explanation on Cronin effect but unfortunately there's no Wikipedia entry or self-contained paper to start from. The statement of this effect is that:
"At leading order, multiple ...
- 1,707
16
votes
4
answers
4k
views
Is forward scattering = no scattering?
What is forward scattering? If it is equivalent to no scattering, then why not call it "no scattering"?
- 5,569
7
votes
1
answer
276
views
What is the mathematical motivation for complexifying momenta in BCFW?
One of the first steps in obtaining the on-shell BCFW recursion relations is complexifying the momenta of the external particles. Now complexifying things is not unprecedented (the dispersion program ...
- 1,124
7
votes
1
answer
2k
views
A certain gluon scattering amplitude
I am stuck with this process of calculating the tree-level scattering amplitude of two positive helicity (+) gluons of momentum say $p_1$ and $p_2$ scattering into two gluons of negative (-) helicity ...
- 4,619
7
votes
1
answer
185
views
Some more questions about the BCFW reduction
This question is a continuation of this previous question of mine and I am continuing with the same notation.
One claims that one can actually split this $n$-gluon amplitude such that there is just ...
- 4,561
7
votes
1
answer
338
views
NMHV 5 Gluon Scattering (Elvang and Huang, Ex 3.11)
In Elvang and Huang's Scattering Amplitudes in Gauge Theory and Gravity, Exercise (3.10) (Exercise (3.11) in the printed version) asks the reader to construct the NMHV scattering amplitude of five ...
- 421
6
votes
1
answer
478
views
Some questions about the BCFW reduction
I am trying to give a fast sketch of what the BCFW reduction does and embed within it some questions at the steps which I don't seem to understand clearly. The first bullet point is sort of a very ...
- 4,561
4
votes
2
answers
186
views
How to compute scattering amplitude $\gamma\pi^+\to\pi^+\pi^0$
I wish to find the amplitude for process $\gamma\pi^+\to\pi^+\pi^0$ at low energies. I am familiar with the basic concepts and techniques of QFT but have never dealt with the scattering processes ...
- 1,586
4
votes
1
answer
1k
views
Callan-Gross relation validity
The inelastic electron-proton scattering cross section can be written as
$$\frac{d\sigma}{dE_2d\Omega}=\frac{\alpha^2}{4*E_1\sin^4{\frac{\theta}{2}}}(W_2\cos^2{{\frac{\theta}{2}}}+2W_1\sin^2{{\frac{\...
- 263
3
votes
1
answer
87
views
Notation: Dividing by a partial differential
Setup
Hi, I am working on a DIS scattering problem in the Light Cone Gauge, and this has me needing to calculate the currents. In doing this, I have come across the following equation
$$
t^a \...
3
votes
0
answers
370
views
What is meant by the "Leading Log Approximation" in the context of the steep rise in gluon distribution at small bjorken x?
I am taking a course in QCD, and we're learning about Regge Theory, Pomeron exchange and structure functions.
I want to know what is meant by the leading log approximation in the context of the gluon ...
- 316
3
votes
0
answers
70
views
Polarized structure functions and Bjorken sum rule
I'm trying to understand what the Bjorken sum rule and the polarized structure functions entering it are. I will use equation (2.3) here as a reference for asking the question.
In Peskin, I've only ...
- 2,921
3
votes
0
answers
356
views
Bjorken Scaling and the Parton Model
It is often said that Bjorken scaling of the deep inelastic structure functions
\begin{equation}
\nu W_2(\nu ,Q^2)\rightarrow F(x)
\end{equation}
(where $Q^2$ is the virtuality of the photon, $\nu=\...
- 2,270
3
votes
0
answers
194
views
Conversion of QCD cross section formula
I'm writing a program to calculate NLO cross sections for semi-inclusive high-$p_T$ pion production in proton-proton-collisions for my bachelor thesis.
I've got a paper describing the production ...
- 337
2
votes
1
answer
80
views
Is Compton Scattering the "Abelian limit" of $qg \rightarrow qg$?
I have calculated the average over initial and sum over final states of the squared amplitude for both Compton scattering $e^-\gamma \rightarrow e^-\gamma$ (QED) and quark-gluon scattering $qg \...
- 321