# Changes between Version 1 and Version 2 of HiggsPheno

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Timestamp:
04/06/12 16:33:02 (7 years ago)
Comment:

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Unmodified
 v1 ==== 1. Decays of the Higgs boson ==== * A light SM Higgs boson mostly decays into %$b\bar b$%. Compute the decay rate for %$H\rightarrow b\bar b$%. * For a Higgs mass of around 160 !GeV, the main decay mode is %$H\rightarrow WW$%. Compute the decay rate. * A light SM Higgs boson mostly decays into $b\bar b$. Compute the decay rate for $H\rightarrow b\bar b$. * For a Higgs mass of around 160 !GeV, the main decay mode is $H\rightarrow WW$. Compute the decay rate. The Higgs branching ratios can be found [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h-br.pdf here]. In the large top mass limit, the gluon fusion production of a Higgs boson can be described by an effective field theory where the Higgs couples directly to the gluons, %$\begin{cal}L\end{cal}=C_H\, H\, G_{\mu\nu}^a\, G_a^{\mu\nu}$%, %$\begin{cal}L\end{cal}=C_H\, H\, G_{\mu\nu}^a\, G_a^{\mu\nu}$, where %$C_H$% is an effective (dimensionful) coupling constant and %$G_{\mu\nu}^a$% denotes the gluon field strength tensor. where $C_H$ is an effective (dimensionful) coupling constant and $G_{\mu\nu}^a$ denotes the gluon field strength tensor. For details on the calculation of the top loop and the effective theory, see the notes and/or check the following Mathematica notebooks (which actually contain much more information): Exercise (DIFFICULT but interesting!!): Use the all the material above to derive the EFT description of a pseudo-scalar Higgs, A, %$\begin{cal}L\end{cal}=C_A\, A\, G_{\mu\nu}^a\, {\tilde G}_a^{\mu\nu}$%, %$\begin{cal}L\end{cal}=C_A\, A\, G_{\mu\nu}^a\, {\tilde G}_a^{\mu\nu}$, where %$C_A$% is an effective (dimensionful) coupling constant and %$G_{\mu\nu}^a$% denotes the gluon field strength tensor and %${\tilde G}''a^{\mu\nu}=\frac12 \epsilon^{\mu\nu\rho\sigma} G''a^{\rho\sigma}$%  is its dual. Compute the loop amplitude, derive  the Feynman rules where $C_A$ is an effective (dimensionful) coupling constant and $G_{\mu\nu}^a$ denotes the gluon field strength tensor and %${\tilde G}''a^{\mu\nu}=\frac12 \epsilon^{\mu\nu\rho\sigma} G''a^{\rho\sigma}$  is its dual. Compute the loop amplitude, derive  the Feynman rules in the large top mass limit and calculate the LO and NLO cross sections at the LHC. Choose a channel and investigate signal and background: 1. The 4 lepton final state: %$pp \to H\to Z Z \to e^+e^- \mu^+ \mu^-$% 1. The 4 lepton final state: $pp \to H\to Z Z \to e^+e^- \mu^+ \mu^-$ * Signal * Events:  [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4l-signal.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4l-signal.lhco.gz Detector Level] * Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4l-lhe.pdf Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4l-lhco.pdf Detector Level] 1. The 2 lepton + missing Et final state: %$pp \to H\to W^+ W^- \to e^- \bar \nu_e \mu^+ \nu_\mu$% 1. The 2 lepton + missing Et final state: $pp \to H\to W^+ W^- \to e^- \bar \nu_e \mu^+ \nu_\mu$ * Signal * Events:  [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-signal.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-signal.lhco.gz Detector Level] * Events:  [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background.lhco.gz Detector Level] * Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background-lhe.pdf Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background-lhco.pdf Detector Level] 1. Top associated production %$pp \to t\bar tH$% with %$H \to b \bar b$% 1. Top associated production $pp \to t\bar tH$ with $H \to b \bar b$ *  Signal + Background samples: * Events:  [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/ttbb.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/ttbb.lhco.gz Detector Level]