|
|
---
|
|
|
title: SPheno and Monte-Carlo tools
|
|
|
permalink: /SPheno_and_Monte-Carlo_tools/
|
|
|
---
|
|
|
# SPheno and Monte-Carlo tools
|
|
|
|
|
|
|
|
|
[Category:SPheno](/Category:SPheno "wikilink")
|
|
|
|
|
|
Model files for MC tools
|
|
|
------------------------
|
... | ... | @@ -37,8 +34,8 @@ Effective diphoton and digluon vertices |
|
|
The effective diphoton and digluon vertices calculated by SPheno are directly available in the UFO model files and the CalcHep model files: SARAH includes the effective vertices for all neutral scalars to two photons and two gluons, and the numerical values for these vertices are read from the spectrum file generated with SPheno. For this purpose, a new block `EFFHIGGSCOUPLINGS` is included in these files, which contains the values for the effective couplings including all corrections outlined in .
|
|
|
It is important to mention that these effective couplings correspond to the decay of the scalar; if we use CalcHep or MadGraph to compute the decay *Φ* → *g**g* then the value matches (as closely as possible) the NNNLO value, which includes *real* emission processes such as *Φ* → *g**g**g*. Therefore, the corrections at NLO and beyond for *Φ* → *g**g* are not the same as *p**p* → *Φ* via gluon fusion ; the full NNNLO production cross-section includes all processes *g**g* → *Φ* + *j**e**t* and is therefore described by a different *k*-factor to the decay. This *k*-factor can for instance be obtained via
|
|
|
|
|
|
$k = c_{\\Phi gg} \\cdot \\frac{\\sigma_{\\rm SM}(pp \\to H(M_{\\Phi})+ \\mathrm{jet})}{\\sigma_{\\rm MC}(pp \\to \\Phi)}$
|
|
|
$`k = c_{\Phi gg} \cdot \frac{\sigma_{\rm SM}(pp \to H(M_{\Phi})+ \mathrm{jet})}{\sigma_{\rm MC}(pp \to \Phi)}`$
|
|
|
|
|
|
where *c*<sub>*Φ**g**g*</sub> is the ratio squared of the effective coupling between *Φ* and two gluons at LO in the considered model and the SM. These values can for instance be read off by the block `HiggsBoundsInputHiggsCouplingsBosons` in the SPhenospectrum file. $\\sigma_{\\rm SM}(pp \\to H(M_{\\Phi}))$ is the cross section for a SM-like Higgs with mass *M*<sub>*Φ*</sub>. This value can be calculated for instance with Higlu or Sushi for the considered center-of-mass energy. SPheno also provides values for $c_{\\Phi gg} \\cdot \\sigma_{\\rm SM}(pp \\to H(M_{\\Phi}))$ for the most common energies in the blocks `HiggsLHCX` (`X`=7,8,13,14) and `HiggsFCC`, see also .
|
|
|
where *c*<sub>*Φ**g**g*</sub> is the ratio squared of the effective coupling between *Φ* and two gluons at LO in the considered model and the SM. These values can for instance be read off by the block `HiggsBoundsInputHiggsCouplingsBosons` in the SPhenospectrum file. $`\sigma_{\rm SM}(pp \to H(M_{\Phi}))`$ is the cross section for a SM-like Higgs with mass *M*<sub>*Φ*</sub>. This value can be calculated for instance with Higlu or Sushi for the considered center-of-mass energy. SPheno also provides values for $`c_{\Phi gg} \cdot \sigma_{\rm SM}(pp \to H(M_{\Phi}))`$ for the most common energies in the blocks `HiggsLHCX` (`X`=7,8,13,14) and `HiggsFCC`, see also .
|
|
|
|
|
|
On the other hand, this approach is not entirely appropriate for more refined collider analyses where the user would like to actually include, for example, a hard jet in the final state (without the full loop corrections to the effective vertex this is not an infra-red safe quantity). |
|
|
\ No newline at end of file |