MadGraph5_aMC@NLO

Can we use FR$LoopSwitches to switch many internal parameters with one and the same external parameter?

Asked by Mustafa Ashry

Hello,

I want to work with UFO at NLO, so I've to generate them first from FeynRules using the package NLOCT.

Can I use the command FR$LoopSwitches = {{x , m1} , {x , m2}}?

I mean can I switch between many internal parameters m1,m2 with one and the same external one x before the OnShellRenormalization?

I'm afraid if I do this, it conflicts with the source of renormalization of x from the many expressions of m1,m2. However, I expect that if the expressions of m1 and m2 are consistent with each others, it will give the same result for x, but I'm not sure if this is the case. Would you clarify please

Thanks in advance

Mustafa

Question information

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Status:
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For:
MadGraph5_aMC@NLO Edit question
Assignee:
celine degrande Edit question
Solved by:
celine degrande
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Last reply:
Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

This is a question for the NLOCT package. I tried to assign Celine to this question.
But it might not work. If she did not reply. Please contact her directly.

Cheers,

Olivier

Revision history for this message
Mustafa Ashry (mashry) said : 		#2

Hello Dr. Olivier,

Thank you so much for your reply.

I've tried it and changed the SM.fr model file so that the Higgs mass to be an internal parameter MH - > 125-Gf as a test trial and set FR$LoopSwitches = {{Gf, MW},{Gf, MH}}; I found that it works efficiently without any error or even warning. So, it seems it works. However, it would be rather better if Celine confirms.

Best Regards

Mustafa

Revision history for this message
Mustafa Ashry (mashry) said : 		#3

Hello Dr. Celine,

This is a kind reminder about my questio, would you.

Thanks in advance
Best regards,
Mustafa

Revision history for this message
celine degrande (cdegrand) said : 		#4

Dear Mustafa,

No. This will not work.

Best,

Celine
________________________________________
From: <email address hidden> [<email address hidden>] on behalf of Mustafa Ashry [<email address hidden>]
Sent: 26 August 2017 17:33
To: Celine Catherine A Degrande
Subject: Re: [Question #655467]: Can we use FR$LoopSwitches to switch many internal parameters with one and the same external parameter?

Question #655467 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/655467

Mustafa Ashry posted a new comment:
Hello Dr. Celine,

This is a kind reminder about my questio, would you.

Thanks in advance
Best regards,
Mustafa

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You received this question notification because you are assigned to this
question.

Revision history for this message
Mustafa Ashry (mashry) said : 		#5

Dear Dr. Celine,

Thank you for your reply.

I wonder if we can then use mass to renormalize another mass, e.g. set FR$LoopSwitches = {{mh , mw} }. I think the answer is NO, would you confirm.

My final question is that when using FR$LoopSwitches = {{x , m} }, should the parameter 'x' appear explcitly in the mass 'm' or it might appear implicitly and it works?

Thank you in advance

Cheers,

Mustafa

Revision history for this message
celine degrande (cdegrand) said : 		#6

Hi Mustafa,

No, you cannot exchange two mass and x has to appear explicitely in m. Basically, I use Solve with the expression of m.

Cheers,

Celine
________________________________________
From: <email address hidden> [<email address hidden>] on behalf of Mustafa Ashry [<email address hidden>]
Sent: 15 September 2017 13:14
To: Celine Catherine A Degrande
Subject: Re: [Question #655467]: Can we use FR$LoopSwitches to switch many internal parameters with one and the same external parameter?

Question #655467 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/655467

    Status: Answered => Open

Mustafa Ashry is still having a problem:
Dear Dr. Celine,

Thank you for your reply.

I wonder if we can then use mass to renormalize another mass, e.g. set
FR$LoopSwitches = {{mh , mw} }. I think the answer is NO, would you
confirm.

My final question is that when using FR$LoopSwitches = {{x , m} },
should the parameter 'x' appear explcitly in the mass 'm' or it might
appear implicitly and it works?

Thank you in advance

Cheers,

Mustafa

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You received this question notification because you are assigned to this
question.

Revision history for this message
Mustafa Ashry (mashry) said : 		#7

Hello Dr. Celine,

Thanks again for your reply.

What if the expression for the mass 'm' is quadratic in the parameter 'x'? In this case, there will be two solutions, I have this situation. and I wonder if you set to choose a specific one of them. Thanks!

Best regards,

Mustafa

Revision history for this message
celine degrande (cdegrand) said : 		#8

Hi,

It will choose the first solution. If you want to choose it yourself, the best is to write directly the model in term of m (as an external) and have x as an internal parameter.

Cheers,

Celine
________________________________________
From: <email address hidden> [<email address hidden>] on behalf of Mustafa Ashry [<email address hidden>]
Sent: 15 September 2017 21:27
To: Celine Catherine A Degrande
Subject: Re: [Question #655467]: Can we use FR$LoopSwitches to switch many internal parameters with one and the same external parameter?

Question #655467 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/655467

    Status: Answered => Open

Mustafa Ashry is still having a problem:
Hello Dr. Celine,

Thanks again for your reply.

What if the expression for the mass 'm' is quadratic in the parameter
'x'? In this case, there will be two solutions, I have this situation.
and I wonder if you set to choose a specific one of them. Thanks!

Best regards,

Mustafa

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You received this question notification because you are assigned to this
question.

Revision history for this message
Mustafa Ashry (mashry) said : 		#9

Hello Dr. Celine,

Thank you for your reply.

I have two parameters x1,x2 such that each of which is a function of the two masses m1,m2. I need then to solve two equations in two variables. Can I use the FR$LoopSwitches command to solve them or the only way is to solve them manually?

What if I have two masses that must be related? That is the number of masses is larger than the number of free parameters. What should I do in this case.

Thanks in advance

Best regards,

Mustafa

Revision history for this message
Best celine degrande (cdegrand) said : 		#10

Dear Mustafa,

You should solve them manually.

Best,

Celine

________________________________________
From: <email address hidden> [<email address hidden>] on behalf of Mustafa Ashry [<email address hidden>]
Sent: 18 September 2017 16:27
To: Celine Catherine A Degrande
Subject: Re: [Question #655467]: Can we use FR$LoopSwitches to switch many internal parameters with one and the same external parameter?

Question #655467 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/655467

    Status: Answered => Open

Mustafa Ashry is still having a problem:
Hello Dr. Celine,

Thank you for your reply.

I have two parameters x1,x2 such that each of which is a function of the
two masses m1,m2. I need then to solve two equations in two variables.
Can I use the FR$LoopSwitches command to solve them or the only way is
to solve them manually?

What if I have two masses that must be related? That is the number of
masses is larger than the number of free parameters. What should I do in
this case.

Thanks in advance

Best regards,

Mustafa

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You received this question notification because you are assigned to this
question.

Revision history for this message
Mustafa Ashry (mashry) said : 		#11

Dear Dr. Celine,

Thank you for your reply.

Best regards,

Mustafa

Revision history for this message
Mustafa Ashry (mashry) said : 		#12

Thanks celine degrande, that solved my question.