CalcHEP

error in Regularization

Asked by Ekaterina

Dear CalcHEP experts!
An error occurred during the regularization of the decay process of a dark matter particle x -> A, e, E (A new model was created for this process).
In the regularization menu, 2 lines were written: 23 - Me - 0 - 2 and 24 - Me - 0 - 2 (the electron mass was entered into the model). The cut was also set, i.e. Е2 - Me / 2 (Min. Bound). Further, when trying to start a Monte-Carlo CalcHEP session, the current window was simply closed. What is my mistake and how can I solve this problem?

Question information

Language:
English Edit question
Status:
Expired
For:
CalcHEP Edit question
Assignee:
No assignee Edit question
Last query:
Last reply:
Revision history for this message
Alexander Belyaev (alexander.belyaev) said : 		#1

Dear Ekaterina,

the problem is in Е2 - Me / 2 cut
the syntax for the cuts is different, it should be

E(A) and not E2, see help in graphical interface (press F1) or see manual

Regards,
Alexander

Revision history for this message
Ekaterina (happykate10) said : 		#2

Dear Alexander,
Thank you for your quick response!
 I fixed the error in Cut, but nothing has changed.
Calculations still just stops and the current window was closed (In the PUTTY window appears ERROR IN REGULARIZATION).
I assume that something is wrong in the Kinematics menu, but I cannot understand what it is, and what kinematic scheme I need to apply. ( this package is new to me)

Revision history for this message
Alexander Pukhov (pukhov) said : 		#3

Here in principle  decay width diverges lithographically. Regularization
procedure does not take into account cut for photon energy in spite it
is enough  to cancel infinity.  To solve problem you have to add small
cuts  for M(e,A) and M(E,A)   , say Me+1E-5.  Regularization  is
sensitive for such cut and now CalcHEP will  know that divergent
squared matrix element   should be integrated out of the pole.

Best

    Alexander Pukhov

PS: this mail was sent  23/11/2018. It seems it was lost.

On 26/11/2018 13:32, Ekaterina wrote:
> Question #676312 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/676312
>
> Status: Answered => Open
>
> Ekaterina is still having a problem:
> Dear Alexander,
> Thank you for your quick response!
> I fixed the error in Cut, but nothing has changed.
> Calculations still just stops and the current window was closed (In the PUTTY window appears ERROR IN REGULARIZATION).
> I assume that something is wrong in the Kinematics menu, but I cannot understand what it is, and what kinematic scheme I need to apply. ( this package is new to me)
>

Revision history for this message
Ekaterina (happykate10) said : 		#4

Dear Alexander!
Thank you for your answer! He was very helpful!
However, I had another question. After the integration, a huge error is obtained. Is there any way to reduce the error?
The particle is almost completely analogous to the Higgs boson, except for the mass. However, for the decay of the Higgs boson with the emission of photons all the calculations are correct and the error is very small.
Thank you!

Revision history for this message
Launchpad Janitor (janitor) said : 		#5

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

Revision history for this message
Alexander Belyaev (alexander.belyaev) said : 		#6

Do you still have the problem?

Revision history for this message
Launchpad Janitor (janitor) said : 		#7

This question was expired because it remained in the 'Needs information' state without activity for the last 15 days.