[Comphep-common] Warning in COMPHEP

[Eduard Boos]

Dear Shilpi,
In addition to what Mikhail explained, you could apply some cuts (say, Pt
cuts on momenta of produced final particles) such that the total invariant
mass of produced particles (sqrt(s_hat=x_1 x_2 s) would not be too small.
If you are modeling the excited lepton production the small s-hat region
is not relevant for your task anyway.

Regards,
             Edward

>
> Dear Shilpi,
>
> Warning! X=7.715561E-07 out of range
>
> and so on is not a CompHEP warning. It is a warning of pdf (partonic
> density functions) library used by CompHEP. When you are using proton
> structure functions (e.g. CTEQ, MRST, etc.) they are evaluating pdf's
> which are functions reconstructed using some fits of experimental data.
> Experimental data (mainly HERA deep inelastic scattering data) is
> available only in the kinematic range x>10^{-3}, where x is scailing
> variable (Bjorken or Feynman variable).
> In your case some object with low effective mass is produced by protons
> s_hat=x_1 x_2 s, so the kinematic range for x is of the order of
> 10^{-7}. Pdf libraries are using some extrapolation based on available
> data at 10^{-3} to the region 10^{-7} and issue a warning on the
> reliability of the result. For detailed information you can address the
> authors of pdf.
> Best regards        Mikhail
>
>
>
> On Sat, 2012-09-29 at 23:40 +0000, Shilpi Jain wrote:
>> Dear Experts,
>>
>> I am trying to generate 10k events in LHE format for the excited
>> leptons model.
>> Following are the steps I follow:
>>
>> (1) ./symn_bath.pl
>> (2) cd results
>>      - ./n_comphep
>>          this way I change my parameters.
>>          I set (a) lambda of the contact interaction theory to 10000
>> GeV,
>>                   (b) mass of excited leptons to 200 GeV,
>>                   (c) Q scale under the options QCD alpha to the mass
>> f the excited leptons i.e. 200 GeV
>>
>> (3) ./num_batch.pl
>> (4) Finally I do ./num_bath.pl -run -lhaef -lsf  -nocombine
>>
>> During this run, I get warnings as given in [1].
>>
>> Please let me know if you think that this is to be worried about and
>> something
>> is going wrong with the calculation.
>>
>> Thanks & Regards,
>> Shilpi
>>
>>
>> [1]
>> ============================================================
>>
>> Warning! X=7.715561E-07 out of range
>> Warning! X=3.166893E-07 out of range
>> Warning! X=3.078189E-07 out of range
>> Warning! X=2.900849E-07 out of range
>> Warning! X=2.078381E-07 out of range
>> Warning! X=4.100108E-07 out of range
>> Warning! X=6.167166E-07 out of range
>> Warning! X=9.738392E-07 out of range
>> Warning! X=6.001850E-07 out of range
>> Warning! X=8.009292E-07 out of range
>> Warning! X=4.481808E-07 out of range
>> Warning! X=9.831972E-07 out of range
>> Warning! X=3.283182E-07 out of range
>> Warning! X=4.226216E-08 out of range
>> Warning! X=8.296989E-07 out of range
>> Warning! X=6.739811E-07 out of range
>> Warning! X=4.899509E-07 out of range
>> Warning! X=8.933945E-07 out of range
>> Warning! X=3.746967E-07 out of range
>> Warning! X=8.780160E-07 out of range
>> Warning! X=6.854185E-07 out of range
>> Warning! X=9.130000E-07 out of range
>> Warning! X=3.783568E-07 out of range
>> Warning! X=2.572710E-07 out of range
>> Warning! X=8.013537E-07 out of range
>>
>> =============================================================
>>
>>
>>
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>
>
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