more simplification of eps

[Karim-Ghorbani]

Hello,
I am running the following program:

Vectors k1, k2, p1, p2, q;
Indices mu, nu, rho, sigma,m1,n1;
Symbols s, t, u, e, mass1, mass2,B,A;
Local
M1 = 1/B^2 * d_(m1,n1)*(g_(1,p2)+mass2)g_(1,m1)(g_(1,p2)-g_(1,q)-mass2)*g_(1,mu)g6_(1)(g_(1,p1)-mass2)g_(1,n1)(g_(1,p2)-g_(1,q)-mass2)*g_(1,nu)*g6_(1) ;

Local M2 = 1/B^2 *g_(2,k2)*g_(2,mu)*g6_(2)*g_(2,k1)*g_(2,nu)*g6_(2) ;
Local M = M1 * M2 ;
Trace4,1;
Trace4,2;
contract;

id p1.p1 = mass2^2 ;
id p2.p2 = mass2^2 ;
id k1.k1 = mass1^2 ;
id k2.k2 = mass1^2 ;
*id k1.k2 = p1.q + p2.q -p1.p2;
id q.q = 0 ;
id mass1 = 0 ;
id mass2^2 = 0 ;

Print +s ;
.end

I get this output:

M =
- 512k1.k2p1.p2p2.qB^-4
- 512k1.p1k2.p2p2.qB^-4
+ 512k1.p2k2.p1p2.qB^-4
+ 512*e_(k1,k2,p1,p2)p2.qB^-4

I would like to get e_(k1,k2,p1,p2) simplified.
Would appreciate any hint for this.
Thank you
Karim

[vermaseren]

Hi, Question: what do you mean with simplified? This is it. If you can make that simpler, either you have a different meaning for that word, or you made a great breakthrough in mathematics. gamma5 can give Levi-Civita tensors in the answer, particularly in CP violating theories. (is always good for some headaches….) Cheers Jos

…

On 25 Apr 2018, at 12:20, Karim-Ghorbani ***@***.***> wrote: Hello, I am running the following program: Vectors k1, k2, p1, p2, q; Indices mu, nu, rho, sigma,m1,n1; Symbols s, t, u, e, mass1, mass2,B,A; Local M1 = 1/B^2 * d_(m1,n1)*(g_(1,p2)+mass2)g_(1,m1)(g_(1,p2)-g_(1,q)-mass2)*g_(1,mu)g6_(1)(g_(1,p1)-mass2)g_(1,n1)(g_(1,p2)-g_(1,q)-mass2)*g_(1,nu)*g6_(1) ; Local M2 = 1/B^2 *g_(2,k2)*g_(2,mu)*g6_(2)*g_(2,k1)*g_(2,nu)*g6_(2) ; Local M = M1 * M2 ; Trace4,1; Trace4,2; contract; id p1.p1 = mass2^2 ; id p2.p2 = mass2^2 ; id k1.k1 = mass1^2 ; id k2.k2 = mass1^2 ; *id k1.k2 = p1.q + p2.q -p1.p2; id q.q = 0 ; id mass1 = 0 ; id mass2^2 = 0 ; Print +s ; .end I get this output: M = - 512k1.k2p1.p2p2.qB^-4 - 512k1.p1k2.p2p2.qB^-4 + 512k1.p2k2.p1p2.qB^-4 + 512*e_(k1,k2,p1,p2)p2.qB^-4 I would like to get e_(k1,k2,p1,p2) simplified. Would appreciate any hint for this. Thank you Karim — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#279>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFLxEkcRzascOj9t36hs0FAMN4QgoKWaks5tsE3lgaJpZM4TjJ8o>.

[tueda]

Maybe it would be nice if you use Markdown syntax, especially code block like

L F = 1*2*3;
P;
.end

(Some characters in FORM programs have special meanings in Markdown.)

[Karim-Ghorbani]

Well, I expect the final results in terms of the involved momenta.

Can you please let me know what is e_(k1,k2,p1,p2) in terms of Levi-Civita tensor and
external momenta k1, k2, p1, p2.

Thanks
Karim

[vermaseren]

That is Schoonschip notation. It is explained in the manual. It means that when the index of a vector is contracted with an index of a function, the vector is placed where the index of the function used to be. This avoids a lot of unnecessary dummy indices. Jos

…

On 25 Apr 2018, at 14:38, Karim-Ghorbani ***@***.***> wrote: Well, I expect the final results in terms of the involved momenta. Can you please let me know what is e_(k1,k2,p1,p2) in terms of Levi-Civita tensor and external momenta k1, k2, p1, p2. Thanks Karim — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#279 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFLxErPqt5iIRFynxHMxEgb4LEHKk9UMks5tsG5UgaJpZM4TjJ8o>.