madspin decay correlation

Hi,

The warning is related to the normal mode madspin and not to the mode without spin correlation.

> So can I use this file in my analysis?

So yes you can use the file in your analysis.

> Does this process have all the spin correlation?

It has the full spin-correlation indeed.
This mode does not include neither off-shell effects or spin correlation between the production and the decay.
The Higgs is the only particle (of the SM) where this mode is actually valid since it has a very small width and is a spin 0 (i.e. they are no correlation between production and decay).

Obviously the idea of using MadSpin is not valid if you are interested in the (non-negligeable) case where the H is offshel and the two Z are on-shell.

Cheers,

Olivier

> On 31 Jan 2017, at 14:13, Amit Adhikary <email address hidden> wrote:
>
> New question #449041 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/449041
>
> After producing Higgs in MadGraph, I decayed Higgs in MadSpin:
>
> h > Z j j , Z > l+ l-
> set spinmode none
>
> and it decayed properly. But in MadSpin card a warning is written : 'Only a succession of 2 body decay are currently allowed". So can I use this file in my analysis? Does this process have all the spin correlation?
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Thanks Olivier Mattelaer, that solved my question.

I have another question here,

       Z boson (spin 1) is also decaying, so is it also spin correlated in this decay?

Thanks in advance.

Hi,

This mode of madspin is (quickly) documented in this paper: arXiv:1507.00020<http://arxiv.org/abs/arXiv:1507.00020>
(see appendix).
In this mode, the decay of the Higgs is done in one block via a standard madevent (actually gridlock) generation.
I.e. the Higgs decay is done as if you have asked
Generate h > z j j, z > l+ l-
And then the generated events are boosted to correspond to the kinematic of the production.
So yes you have the full correlation in the decay of the Higgs.

Cheers,

Olivier

On 31 Jan 2017, at 14:57, Amit Adhikary <<email address hidden><mailto:<email address hidden>>> wrote:

Question #449041 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/449041

   Status: Solved => Open

Amit Adhikary is still having a problem:
I have another question here,

      Z boson (spin 1) is also decaying, so is it also spin correlated in this decay?

Thanks in advance.

--
You received this question notification because you are an answer
contact for MadGraph5_aMC@NLO.

Thank you very much Olivier. I have understood.