Invariant mass cut (maximum) for known pdg codes

If you set yourself in four flavor. you can use
mmjj and mmjjmax for such cut.

Cheers,

Olivier

> On 9 Mar 2022, at 04:25, GSA <email address hidden> wrote:
>
> New question #700864 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/700864
>
> Hello,
>
>
> I'm running the process mu+ mu- > b s~ vl vl~ after importing the sm-ckm. I don't quite see a direct way to implement a maximum cut on the invariant mass of the b s~ pair. I believe that I can set the lower bound by using mxx_min_pdg with something like "{{5,3}:30} = mxx_min_pdg" for the strange-bottom pair. I'd like to figure out how to do the same for a maximum (I read that it couldn't be done for unknown PDG codes, but these are well defined, known codes).
>
> Thank you in advance to any kind people who might offer their help.
>
> Best,
> Adi
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Thank you for taking the time to respond!

I'm not quite sure how one would do that, as maxjetflavor was set to 4 by default, but I didn't see any mmjj or mmjjmax options. When I used the commands "set mmjj 9600" and "set mmjjmax 10400" after doing "set ebeam1 5000" and "set ebeam2 5000", I didn't find any difference in the cross section, relative to the evaluation without cuts.

What I do find changed is that in the run file, I see this:
*******************************************************************
# Additional hidden parameters
#*********************************************************************
  10400.0 = mmjjmax # hidden_parameter
  9600.0 = mmjj # hidden_parameter

If you have another minute, please do let me know if I am failing to follow your helpful directions. The only other thing I can think of is to change the "j" definition to being only the 4 light quarks.

Thanks again for your help.

That seems to have worked quite well. Thank you Olivier Mattelaer, I appreciate your kind help!

The branching fraction measurement of B0
s → μ+μ− and B0 → μ+μ− is one of the key
analysis for the LHCb experiment. These branching fractions are predicted to be very
small in the Standard Model and are highly sensitive to effects beyond the Standard
Model. Therefore these decays can be used to detect indirectly New Physics.
LHCb has published this year a result based on 2010 data. No signal was observed and
an upper limit for the branching fractions has been set.
One of the corner stones in this analysis at LHCb is the determination of the invariant
mass distribution of the two muons for signal and background. The parameters of the
signal distribution must be estimated from decays similar to B0
(s) → μ+μ− such as
B0
(s) → (π+/K+)(π−/K−) or ψ(nS)/Υ (nS) → μ+μ− as no signal for B0
(s) → μ+μ−
has been observed. A special focus in the determination of the parameters lies in the
estimation of the systematic errors.
This thesis provides the determination of the invariant dimuon mass distribution and its
statistical and systematic errors based on the 2010 data with different methods which
have led to compatible results
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