MadGraph5_aMC@NLO

Higgs to bbar BR in SM model wrong ?

Asked by Ricardo Barrué

Hello, I'm simulating Higgs associated production in Madgraph with h -> b b~ with the sm that comes with the program.

When I calculate the cross-sections without any cuts I get:

1. sigma (p p > w+ > w+ h) = 686.1 fb

2. sigma (p p > w+ > w+ h, h > b b~) = 566.4 fb

When I 2. by 1. I get around 83%. Shouldn't it be 58% as that's the Higgs BR to bottom quarks ?

I'm probably missing something, can someone help me ?

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

The LO (including Loop-induced channel) BR for the Higgs are the following one:

# PDG Width
DECAY 25 5.621956e-03
# BR NDA ID1 ID2 ...
   7.657121e-01 2 -5 5 # 0.00430479973487
   4.602490e-02 2 -15 15 # 0.000258749962704
   3.470500e-02 2 21 21 # 0.00019510998298
   2.306937e-02 3 -2 1 24 # 0.000129694983088
   2.306937e-02 3 -4 3 24 # 0.000129694983088
   2.283547e-02 3 -24 -1 2 # 0.000128380007579
   2.283547e-02 3 -24 -3 4 # 0.000128380007579
   7.638622e-03 3 -12 11 24 # 4.29439967846e-05
   7.638622e-03 3 -14 13 24 # 4.29439967846e-05
   7.589707e-03 3 -24 -11 12 # 4.26689988069e-05
   7.589707e-03 3 -24 -13 14 # 4.26689988069e-05
   7.549329e-03 3 -16 15 24 # 4.24419954675e-05
   7.536878e-03 3 -24 -15 16 # 4.23719964934e-05
   2.265759e-03 3 -1 1 23 # 1.27379974046e-05
   2.265759e-03 3 -3 3 23 # 1.27379974046e-05
   1.821430e-03 3 -5 5 23 # 1.02399993171e-05
   1.776873e-03 3 -2 2 23 # 9.98950182359e-06
   1.776873e-03 3 -4 4 23 # 9.98950182359e-06
   1.726125e-03 2 22 22 # 9.7041988005e-06
   1.019633e-03 3 -12 12 23 # 5.73233186215e-06
   1.019633e-03 3 -14 14 23 # 5.73233186215e-06
   1.019633e-03 3 -16 16 23 # 5.73233186215e-06
   5.073945e-04 3 -11 11 23 # 2.85254955364e-06
   5.073945e-04 3 -13 13 23 # 2.85254955364e-06
   4.989544e-04 3 -15 15 23 # 2.80509968281e-06

So much bigger than 58%.
If you want to be fully consistent at LO, you should then put the LO value for width:5.621956e-03.
Otherwise you will not get the 76% quoted above.

Cheers,

Olivier

On 27 May 2018, at 20:47, Ricardo Barrué <<email address hidden><mailto:<email address hidden>>> wrote:

p p > w+ > w+ h, h > b b~

Can you help with this problem?

Provide an answer of your own, or ask Ricardo Barrué for more information if necessary.

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