Negative cross section and huge % error in a spin-3/2 model implementation

c_source/symb/reader0.c contains  routine  spin3_2_propagator.

In the end it has

      return txt;

     }

printf this txt before "return"

     printf(" spin3/2 propagator=%s\n", txt);

     return txt;

     }

You can compare it with fermion propagator :  fermPropagTxt

denomination of propagator

1/(m^2-p^2) part

is universal for all particles.

May be some term in your lagrangian are imaginary?  I  tested spin3/2
processes recently.

I can look at your problem if you find a 2->2 process with negative
cross section.

Best

    Alexander Pukhov

On 06/01/2018 02:17 PM, OZAN wrote:
> New question #669836 on CalcHEP:
> https://answers.launchpad.net/calchep/+question/669836
>
> Hi,
> We are trying to implement a spin-3/2 extension to the SM. No matter what we do (cuts, regularizations and all), we get negative cross section for the processes g,g -> H,H, nu,nubar and q,q_bar-> H,H,nu,nubar . We are using the H^2 F^2 effective vertex so we should be fine there as far as the gauge invariance is concerned . During our detailed analysis; we figured out that the negative x-section stems from the cross-terms which come out while we take the square of the sum of a diagram and its conjugate diagram; i.e. when we delete the squared diagrams in which the nötrinos are cross matched the problem evaporates. We suspect that there is a problem with the spin-3/2 propagator which is implemented in Calchep. Probably the propagator is missing an "i" . Because, when we insert an "i" in ( H spin-3/2 nu) vertex and a "-i" in (H spin3/2_bar nu_bar) vertex, the negativeness of the cross section goes away. So, what I am asking is: Is there a way for the user to access the spin-3/2 propagator in Calchep so that we can check it. If not; could you do it for us. For example in the paper https://arxiv.org/pdf/1308.1668v1.pdf there is no reference to "i" in the propagator.
>
> Best
> Ozan.
>

 Could you send us your model,
please?
Alexander

On Fri, 1 Jun 2018, 17:37 Alexander Pukhov, <
<email address hidden>> wrote:

> Question #669836 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/669836
>
> Status: Open => Answered
>
> Alexander Pukhov proposed the following answer:
> c_source/symb/reader0.c contains routine spin3_2_propagator.
>
> In the end it has
>
> return txt;
>
> }
>
> printf this txt before "return"
>
>
> printf(" spin3/2 propagator=%s\n", txt);
>
> return txt;
>
> }
>
>
> You can compare it with fermion propagator : fermPropagTxt
>
> denomination of propagator
>
> 1/(m^2-p^2) part
>
> is universal for all particles.
>
>
> May be some term in your lagrangian are imaginary? I tested spin3/2
> processes recently.
>
> I can look at your problem if you find a 2->2 process with negative
> cross section.
>
> Best
>
> Alexander Pukhov
>
>
>
> On 06/01/2018 02:17 PM, OZAN wrote:
> > New question #669836 on CalcHEP:
> > https://answers.launchpad.net/calchep/+question/669836
> >
> > Hi,
> > We are trying to implement a spin-3/2 extension to the SM. No matter
> what we do (cuts, regularizations and all), we get negative cross section
> for the processes g,g -> H,H, nu,nubar and q,q_bar-> H,H,nu,nubar . We are
> using the H^2 F^2 effective vertex so we should be fine there as far as the
> gauge invariance is concerned . During our detailed analysis; we figured
> out that the negative x-section stems from the cross-terms which come out
> while we take the square of the sum of a diagram and its conjugate
> diagram; i.e. when we delete the squared diagrams in which the nötrinos
> are cross matched the problem evaporates. We suspect that there is a
> problem with the spin-3/2 propagator which is implemented in Calchep.
> Probably the propagator is missing an "i" . Because, when we insert an
> "i" in ( H spin-3/2 nu) vertex and a "-i" in (H spin3/2_bar nu_bar)
> vertex, the negativeness of the cross section goes away. So, what I am
> asking is: Is there a way for the user to access the spin-3/2 propagator in
> Calchep so that we can check it. If not; could you do it for us. For
> example in the paper https://arxiv.org/pdf/1308.1668v1.pdf there is no
> reference to "i" in the propagator.
> >
> > Best
> > Ozan.
> >
>
> --
> You received this question notification because your team CalcHEP is an
> answer contact for CalcHEP.
>
--

___________________________
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 (0)23 8059 8509

Hi,
I have sent you the model files by e-mail. Does the suggestion by Dr. Pukhov work in batch mode? I mean, while using the graphical interface it doesn't print anything to the terminal.
Thanks.
Best.
Ozan.

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

I am still having this problem, please reopen my question. Thanks.

On Sun, Jun 17, 2018 at 10:17 AM, Launchpad Janitor <
<email address hidden>> wrote:

> Your question #669836 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/669836
>
> Status: Open => Expired
>
> Launchpad Janitor expired the question:
> This question was expired because it remained in the 'Open' state
> without activity for the last 15 days.
>
> --
> If you're still having this problem, you can reopen your question either
> by replying to this email or by going to the following page and
> entering more information about your problem:
> https://answers.launchpad.net/calchep/+question/669836
>
> You received this question notification because you asked the question.
>

Do you see problem only for 2-> 4 processes?

If you meet such problem with 2->2 type of reaction  it will be simple
to  catch the problem.

If you have not input/output gauge bosons, the the only source of
negative cross section is non-hermit   vertex. If you send me list of
involved vertices, I can check their self-conjugation.

Best

   Alexander Pukhov

On 06/17/2018 10:57 AM, OZAN wrote:
> Question #669836 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/669836
>
> Status: Expired => Open
>
> OZAN is still having a problem:
> I am still having this problem, please reopen my question. Thanks.
>
> On Sun, Jun 17, 2018 at 10:17 AM, Launchpad Janitor <
> <email address hidden>> wrote:
>
>> Your question #669836 on CalcHEP changed:
>> https://answers.launchpad.net/calchep/+question/669836
>>
>> Status: Open => Expired
>>
>> Launchpad Janitor expired the question:
>> This question was expired because it remained in the 'Open' state
>> without activity for the last 15 days.
>>
>> --
>> If you're still having this problem, you can reopen your question either
>> by replying to this email or by going to the following page and
>> entering more information about your problem:
>> https://answers.launchpad.net/calchep/+question/669836
>>
>> You received this question notification because you asked the question.
>>

Hi Dr. Pukhov,
First of all thank you for your answer. I have sent my model files to your
e-mail address.
There are no 2->2 BSM processes in my model and there are no problems with
the SM 2->2 processes. However, the same problem exists, for example, for
g, g -> H, ve, ve~.
Thank you.
Best Ozan.

On Mon, Jun 18, 2018 at 12:17 PM, Alexander Pukhov <
<email address hidden>> wrote:

> Your question #669836 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/669836
>
> Status: Open => Answered
>
> Alexander Pukhov proposed the following answer:
> Do you see problem only for 2-> 4 processes?
>
> If you meet such problem with 2->2 type of reaction it will be simple
> to catch the problem.
>
> If you have not input/output gauge bosons, the the only source of
> negative cross section is non-hermit vertex. If you send me list of
> involved vertices, I can check their self-conjugation.
>
> Best
>
> Alexander Pukhov
>
>
> On 06/17/2018 10:57 AM, OZAN wrote:
> > Question #669836 on CalcHEP changed:
> > https://answers.launchpad.net/calchep/+question/669836
> >
> > Status: Expired => Open
> >
> > OZAN is still having a problem:
> > I am still having this problem, please reopen my question. Thanks.
> >
> > On Sun, Jun 17, 2018 at 10:17 AM, Launchpad Janitor <
> > <email address hidden>> wrote:
> >
> >> Your question #669836 on CalcHEP changed:
> >> https://answers.launchpad.net/calchep/+question/669836
> >>
> >> Status: Open => Expired
> >>
> >> Launchpad Janitor expired the question:
> >> This question was expired because it remained in the 'Open' state
> >> without activity for the last 15 days.
> >>
> >> --
> >> If you're still having this problem, you can reopen your question either
> >> by replying to this email or by going to the following page and
> >> entering more information about your problem:
> >> https://answers.launchpad.net/calchep/+question/669836
> >>
> >> You received this question notification because you asked the question.
> >>
>
> --
> If this answers your question, please go to the following page to let us
> know that it is solved:
> https://answers.launchpad.net/calchep/+question/669836/+
> confirm?answer_id=5
>
> If you still need help, you can reply to this email or go to the
> following page to enter your feedback:
> https://answers.launchpad.net/calchep/+question/669836
>
> You received this question notification because you asked the question.
>

Indeed improved attachment

Best

On 06/18/2018 01:58 PM, OZAN wrote:
> Question #669836 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/669836
>
> Status: Answered => Open
>
> OZAN is still having a problem:
> Hi Dr. Pukhov,
> First of all thank you for your answer. I have sent my model files to your
> e-mail address.
> There are no 2->2 BSM processes in my model and there are no problems with
> the SM 2->2 processes. However, the same problem exists, for example, for
> g, g -> H, ve, ve~.
> Thank you.
> Best Ozan.
>
> On Mon, Jun 18, 2018 at 12:17 PM, Alexander Pukhov <
> <email address hidden>> wrote:
>
>> Your question #669836 on CalcHEP changed:
>> https://answers.launchpad.net/calchep/+question/669836
>>
>> Status: Open => Answered
>>
>> Alexander Pukhov proposed the following answer:
>> Do you see problem only for 2-> 4 processes?
>>
>> If you meet such problem with 2->2 type of reaction it will be simple
>> to catch the problem.
>>
>> If you have not input/output gauge bosons, the the only source of
>> negative cross section is non-hermit vertex. If you send me list of
>> involved vertices, I can check their self-conjugation.
>>
>> Best
>>
>> Alexander Pukhov
>>
>>
>> On 06/17/2018 10:57 AM, OZAN wrote:
>>> Question #669836 on CalcHEP changed:
>>> https://answers.launchpad.net/calchep/+question/669836
>>>
>>> Status: Expired => Open
>>>
>>> OZAN is still having a problem:
>>> I am still having this problem, please reopen my question. Thanks.
>>>
>>> On Sun, Jun 17, 2018 at 10:17 AM, Launchpad Janitor <
>>> <email address hidden>> wrote:
>>>
>>>> Your question #669836 on CalcHEP changed:
>>>> https://answers.launchpad.net/calchep/+question/669836
>>>>
>>>> Status: Open => Expired
>>>>
>>>> Launchpad Janitor expired the question:
>>>> This question was expired because it remained in the 'Open' state
>>>> without activity for the last 15 days.
>>>>
>>>> --
>>>> If you're still having this problem, you can reopen your question either
>>>> by replying to this email or by going to the following page and
>>>> entering more information about your problem:
>>>> https://answers.launchpad.net/calchep/+question/669836
>>>>
>>>> You received this question notification because you asked the question.
>>>>
>> --
>> If this answers your question, please go to the following page to let us
>> know that it is solved:
>> https://answers.launchpad.net/calchep/+question/669836/+
>> confirm?answer_id=5
>>
>> If you still need help, you can reply to this email or go to the
>> following page to enter your feedback:
>> https://answers.launchpad.net/calchep/+question/669836
>>
>> You received this question notification because you asked the question.
>>