Comment 3 for bug 1818393

Hey Alexander,

I’ve tried running in both gauges, but this doesn’t seem to have changed anything.

This only happens for me when I run \Chi + ~\Chi -> Zp Zp , with \Chi being the dirac dark matter candidate and Zp the new Z-prime. I was evaluating the cross sections at center of mass energies near the dark matter mass, and the problem seemed to persist across a wide range of energies.

I also tried modifying the nTypes.h file as recommended, but the problem still remains…

Best,

Sam

> On Mar 4, 2019, at 2:08 AM, Alexander Belyaev <email address hidden> wrote:
>
> Which process (initial state particles) and which energies you are
> talking about?
>
> Regards,
>
> Alexander
>
>
> On 03/03/2019 10:12, Sam Witte wrote:
>> Public bug reported:
>>
>> I'm encountering an error message while running n_calchep for a very
>> simple model in which a Z' couples to first generation leptons (with
>> purely vectorial couplings) and to a dirac dark matter candidate (with
>> purely vectorial couplings). When the ratio of the dark matter coupling
>> to standard model coupling is large (ie one has a dark sector-like
>> model), and when the Z' mass is less than about 2 \times 10^3 M_{dark
>> matter} (for example, take the dark matter mass of 3 TeV, the Z' mass of
>> 0.1 GeV, dark matter couplings of 1, and SM couplings of 0.1), I find an
>> error in the calculation of the cross section, with the error message
>> reading 'Lost of precision in SQME'. I've tried adjusting things like
>> the precision of the calculation, and I've tested this with 3 different
>> model files (written by 3 different individuals).
>>
>> Have you encountered a problem like this before, and if so is there an
>> easy fix?
>>
>> Thank you!
>>
>> ** Affects: calchep
>> Importance: Undecided
>> Status: New
>>
> --
> ______________________________________________________________________
> Prof. Alexander S Belyaev (<email address hidden>)
> https://www.hep.phys.soton.ac.uk/content/alexander-belyaev
>
> School of Physics & Astronomy, University of Southampton
> Office 5047, SO17 1BJ, TEL: +44 23805 98509, FAX: +44 23805 93910
> .....................................................................
> Particle Physics Department, Rutherford Appleton Laboratory
> Didcot, OX11 0QX, TEL: +44 12354 45562, FAX: +44 12354 46733
> .....................................................................
> CERN, CH-1211 Geneva 23, Switzerland
> Office 40/1-B20, Mailbox: E27910, TEL: +41 2276 71642
> ______________________________________________________________________
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1818393
>
> Title:
> Loss of precision in SQME
>
> Status in CalcHEP:
> New
>
> Bug description:
> I'm encountering an error message while running n_calchep for a very
> simple model in which a Z' couples to first generation leptons (with
> purely vectorial couplings) and to a dirac dark matter candidate (with
> purely vectorial couplings). When the ratio of the dark matter
> coupling to standard model coupling is large (ie one has a dark
> sector-like model), and when the Z' mass is less than about 2 \times
> 10^3 M_{dark matter} (for example, take the dark matter mass of 3 TeV,
> the Z' mass of 0.1 GeV, dark matter couplings of 1, and SM couplings
> of 0.1), I find an error in the calculation of the cross section, with
> the error message reading 'Lost of precision in SQME'. I've tried
> adjusting things like the precision of the calculation, and I've
> tested this with 3 different model files (written by 3 different
> individuals).
>
> Have you encountered a problem like this before, and if so is there an
> easy fix?
>
> Thank you!
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/calchep/+bug/1818393/+subscriptions