Thanks a lot. This reminds me that the red photon no-longer has a definite momentum, and the situation is similar to the case of understanding soft or collinear divergences.
I am thinking about a problem. Consider the forward Compton scattering process e(p)+γ(k) -> e(p)+γ(k), as shown in the following figure.
If we consider the initial red photon is emitted by another electron which then goes to anything, then how can we write down the whole amplitude for this...
Dear friends:
It's strange that Mathematica can do the integral of ##\int_0^\infty dx~x~_2F_1(a,b,c,1-x^2)##, however, fails when it's changed to ##\int_0^\infty dx~x~_2F_1(a,b,c,1-x-x^2)##.
Are there any major differences between this two types? Is it possible to do the second kind of integral...
Thanks. I opened a new notebook and did the settings you mentioned, but got the same wrong result.
However, to my surprise, I just changed the variable name from ε to b, and the output changed. :eek:
The version of mine is 11.1
Maybe it's a bug? and fixed in 11.2 :oldconfused:
I calculated a simple complex function integration using Mathematica 11.
As the screenshot shows, the only difference between the two inputs is that I set a = 1 in the second one.
However, the two outputs differ by a factor of 2.
What's wrong? Is this a bug?
It's very kind of you to give the help. Thank you very much.
I found the solution to clear workspace from official forums:
load_package "reset";
resetreduce;
For gamma matrix trace with index, I found the solution from the manual, by loading the package "CVIT".
For example, if I want to calculate ##Tr(\gamma^\mu\gamma^\nu)\cdot Tr(\gamma_\mu\gamma_\nu)=64##
I write:
index mu, nu;
ans := 4*g(L1, mu, nu) * 4*g(L2, mu, nu);
;end;
The "4" is because Reduce always calculate 1/4 times the trace.
This will give 64, no problem.
But if I write:
index mu, nu...
Thank you!
Well, this is actually not a serious problem, because I can always reload Reduce.
But I now encounter a more realistic problem.
When Reduce does Dirac Gamma matrix trace, the indices must always be matched (appear in pair).
However, if I just want to calculate, say, the leptonic...
Hi, everyone,
I am now using "Reduce", a software system based on "Lisp" for general algebraic computations.
Does anyone use this software and know how to clear workspace before doing calculation?
Just like "clear all" in MATLAB.
I read from the user's manual that the command "clear x, y, ..."...
Hi, everyone,
I am now looking for a good textbook on QCD.
I am especially want to learn the derivation of DGLAP evolution equations.
So, it will be better if the book contains the detailed derivation of evolution equations step by step for all the diagrams using Feynman rules.
I looked through...
Oops, sorry for my ambiguity. Actually I mean the quarks fragment into hadrons, i.e. the fragmentation function is ##D^{q\to h}## with ##h = K^{*0}(892)##, and ##q = u,d,s,c,\cdots##.
For ##h = pion, kaon...##, it is available(given by online FF generator), but what about ##K^{*0}##?
Where can I find the fragmentation function (FF) of ##K^{*0}(892)## particle?
The online FF generator doesn't give the option of ##K^{*0}##
FF generator: http://lapth.cnrs.fr/ffgenerator/
Textbooks tell us that a four vector under time reversal changes as ##x^\mu \to \tilde x^\mu = x_\mu##, and ##i \to -i##. The gluon field changes as ##A^\mu(x) \to A_\mu(-\tilde x)##.
My question is how does the following integral (the wilson line in the perpendicular direction) change unter...