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Old Aug 2nd 2013, 03:24 AM   #1
SRS
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Join Date: Aug 2013
Posts: 2
Higgs production and pDF

Hi all,

I try to calculate the Higgs production cross section by Mathematica using
for example the formula in [arXiv:hep-ph/0503172].

The problem comes when I calculate " σ_0 " it's of order 10^-10 pb at mh = 125 GeV, then when I convolute with the parton distribution function to get the pp -> H production according to equ.( 3.58) it gives me of order 10^-7 pb !! while in the plot (3.18) pp -> H is around 50 pb.

Here is my calculation;

for σ0:

σ0[mh_] : = ( ( c^2)/ (256 *Pi)) *(1/2)^2* ( ((Yht)/(mT))* At [mh])^2
where
c = 0.117, Yht= mt/v, v= 174 and At is the fermion loop function.

For σ(pp -> h) I used:

LogPlot[ {σ0[mh]*(q)* NIntegrate[(1/x)* pdf[iset, iparton, x, 14000] * pdf[iset, iparton, (q/x), 14000], {x, q, 1}], {mh, 100, 200}]

With

iset = 1; (* CTEQ5M*)
iparton = 0;
q := mh^2/14000^2;

I don't know what is the problem I have, any help please,
Thanks,
Safinaz
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Old Aug 3rd 2013, 12:04 PM   #2
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Originally Posted by SRS View Post
Hi all,

I try to calculate the Higgs production cross section by Mathematica using
for example the formula in [arXiv:hep-ph/0503172].

The problem comes when I calculate " σ_0 " it's of order 10^-10 pb at mh = 125 GeV, then when I convolute with the parton distribution function to get the pp -> H production according to equ.( 3.58) it gives me of order 10^-7 pb !! while in the plot (3.18) pp -> H is around 50 pb.

Here is my calculation;

for σ0:

σ0[mh_] : = ( ( c^2)/ (256 *Pi)) *(1/2)^2* ( ((Yht)/(mT))* At [mh])^2
where
c = 0.117, Yht= mt/v, v= 174 and At is the fermion loop function.

For σ(pp -> h) I used:

LogPlot[ {σ0[mh]*(q)* NIntegrate[(1/x)* pdf[iset, iparton, x, 14000] * pdf[iset, iparton, (q/x), 14000], {x, q, 1}], {mh, 100, 200}]

With

iset = 1; (* CTEQ5M*)
iparton = 0;
q := mh^2/14000^2;

I don't know what is the problem I have, any help please,
Thanks,
Safinaz
I can't seem to get arXiv to reference that paper itself...it keeps sending me to the Cornell U. library and it won't let me view the article.

Question: The 50 pb...is this a measurement or is it a theoretical calculation? I would like to see how you did the calculation if so.

-Dan
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Old Aug 4th 2013, 12:05 AM   #3
SRS
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Join Date: Aug 2013
Posts: 2
Hi,

I went on the theoretical calculation with no problem and get

σ0[mh_] : = ( ( \alpha_s^2)/ (256 *Pi)) *(1/2)^2* ( ((Yht)/(mT))* At [mh])^2

This consists with the formula look for example
J.M.S. Wu, Phys. Rev. D 86, 033003(2012)

My main problem is to dealing with the PDF to get \sigma(pp -> H) at last.
I can send you the Math. file in which I tried but please let me know your mail.

Best,
S.
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