[Comphep-common] [Fwd: Re: problems with compHEP (Cross- Section)]

[Alexander Kryukov]

Dear David!

I think that we fix the bug. Please take last version of CompHEP from
the Web:

http://theory.sinp.msu.ru/comphep

Many thanks for report! If you wish to receive regular information about
CompHEP project, please sign on the mail list:

http://theory.sinp.msu.ru/mailman/listinfo/comphep-common

                     Best wishes,        Alexander

On Mon, 2004-04-26 at 23:20, David C. Papencordt wrote:
> Dear Alexander!
> Some time ago, I wrote you about my problems with a special compHEP
> process (see below). Now I'd like to know if you already analysed it?
> 
> Looking forward to an answer and best wishes,    David
> 
> 
> 
> Am Die, 2004-02-10 um 10.45 schrieb Alexander Kryukov:
> > Dear David!
> > 
> > Thanks a lot of the report. We investigate the problem and report about results 
> > as soon as possible.
> > 
> >                    Best wishes,           Alexander
> > 
> > p11y001 at public.uni-hamburg.de wrote:
> > > Dear Alexander Kryukov!
> > > 
> > > I'm using compHEP to simulate the process pb,pb->m,M and I have the problem of
> > > an unexplainable Cross Section. Perhaps you can help me with this.
> > > 
> > > I will specify my settings first:
> > > 
> > > compHEP version: 4.2.0
> > > model: SM, Feynman gauge
> > > pb consist of: u,U,d,D,s,S,c,C,b,B,G
> > > CMS energy: 14000 GeV
> > > structure function: both cteq6l1
> > > cuts: T3    6   7000
> > >       T4    6   7000
> > >      A13    5    175
> > >      A14    5    175
> > > Distributions:  T3   0   7000
> > >                 T4   0   7000
> > >                C13   -1   1
> > >                C14   -1   1
> > > 
> > > 
> > > After generating events, I have the following Cross Sections:
> > > uU->mM:  7.28159E+02
> > > dD->mM:  3.21322E+02
> > > cC->mM:  6.35663E+03   (<- much to high?)
> > > sS->mM:  1.73509E+02
> > > 
> > > It seems to me, that the CS from the subprocess cC->mM is much to high, while
> > > the others seem to be ok.
> > > The same problem occurs, when I try to estimate the number of events (N) per
> > > sec. For this I use the vegas integration and display T3 with 2 bins. While the
> > > the second bin is negligible, I take the CS from the first one and calculate N
> > > with an expected Luminosity (L) of 10^34 (N=CS*L).
> > > Here are my results:
> > > uU->mM: 28,8 events per sec
> > > dD->mM: 12.8 e.p.s.
> > > cC->mM: 447 e.p.s.   (!)
> > > sS->mM: 7 e.p.s.
> > > 
> > > As you can see, because of the very high CS of the cC subprocess, I have even
> > > more events than from the uU one, althouhg I consider a proton - proton collision! 
> > > 
> > > I have no explanation for that. 
> > > 
> > > Perhaps you can help me with this? Is there a known bug in the program? 
> > > 
> > > Thanks a lot!
> > > Yours sincerely,
> > > 
> > > David Papencordt
> > 
> > -- 
> > Dr. Alexander Kryukov
> > Inst. of Nucl. Phys, Moscow State Univ,| INFN, Padua (until 11/02/2004)
> > Leninskie gory-1, 119992, Moscow,RUSSIA| Via Marzolo 8, 35131 Padova-Italy
> > +7(095)939-2875, bld. KFVE, room 404   | Phone: +39(049)827-7099, Off. 139
> > 
> > 
-- 
Alexander Kryukov <kryukov at theory.sinp.msu.ru>
SINP MSU