Changes between Version 1 and Version 2 of HiggsPheno
 Timestamp:
 04/06/12 16:33:02 (7 years ago)
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HiggsPheno
v1 v2 5 5 6 6 ==== 1. Decays of the Higgs boson ==== 7 * A light SM Higgs boson mostly decays into %$b\bar b$%. Compute the decay rate for %$H\rightarrow b\bar b$%.8 * For a Higgs mass of around 160 !GeV, the main decay mode is %$H\rightarrow WW$%. Compute the decay rate.7 * A light SM Higgs boson mostly decays into $b\bar b$. Compute the decay rate for $H\rightarrow b\bar b$. 8 * For a Higgs mass of around 160 !GeV, the main decay mode is $H\rightarrow WW$. Compute the decay rate. 9 9 The Higgs branching ratios can be found [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hbr.pdf here]. 10 10 … … 15 15 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, 16 16 17 %$\begin{cal}L\end{cal}=C_H\, H\, G_{\mu\nu}^a\, G_a^{\mu\nu}$ %,17 %$\begin{cal}L\end{cal}=C_H\, H\, G_{\mu\nu}^a\, G_a^{\mu\nu}$, 18 18 19 where %$C_H$% is an effective (dimensionful) coupling constant and %$G_{\mu\nu}^a$%denotes the gluon field strength tensor.19 where $C_H$ is an effective (dimensionful) coupling constant and $G_{\mu\nu}^a$ denotes the gluon field strength tensor. 20 20 21 21 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): … … 27 27 Exercise (DIFFICULT but interesting!!): Use the all the material above to derive the EFT description of a pseudoscalar Higgs, A, 28 28 29 %$\begin{cal}L\end{cal}=C_A\, A\, G_{\mu\nu}^a\, {\tilde G}_a^{\mu\nu}$ %,29 %$\begin{cal}L\end{cal}=C_A\, A\, G_{\mu\nu}^a\, {\tilde G}_a^{\mu\nu}$, 30 30 31 where %$C_A$% is an effective (dimensionful) coupling constant and %$G_{\mu\nu}^a$%denotes the gluon field strength tensor and32 %${\tilde G}''a^{\mu\nu}=\frac12 \epsilon^{\mu\nu\rho\sigma} G''a^{\rho\sigma}$ %is its dual. Compute the loop amplitude, derive the Feynman rules31 where $C_A$ is an effective (dimensionful) coupling constant and $G_{\mu\nu}^a$ denotes the gluon field strength tensor and 32 %${\tilde G}''a^{\mu\nu}=\frac12 \epsilon^{\mu\nu\rho\sigma} G''a^{\rho\sigma}$ is its dual. Compute the loop amplitude, derive the Feynman rules 33 33 in the large top mass limit and calculate the LO and NLO cross sections at the LHC. 34 34 … … 41 41 Choose a channel and investigate signal and background: 42 42 43 1. The 4 lepton final state: %$pp \to H\to Z Z \to e^+e^ \mu^+ \mu^$%43 1. The 4 lepton final state: $pp \to H\to Z Z \to e^+e^ \mu^+ \mu^$ 44 44 * Signal 45 45 * Events: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4lsignal.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4lsignal.lhco.gz Detector Level] … … 49 49 * Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4llhe.pdf Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/h4llhco.pdf Detector Level] 50 50 51 1. The 2 lepton + missing Et final state: %$pp \to H\to W^+ W^ \to e^ \bar \nu_e \mu^+ \nu_\mu $%51 1. The 2 lepton + missing Et final state: $pp \to H\to W^+ W^ \to e^ \bar \nu_e \mu^+ \nu_\mu $ 52 52 * Signal 53 53 * Events: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hwwsignal.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hwwsignal.lhco.gz Detector Level] … … 56 56 * Events: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hwwbackground.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hwwbackground.lhco.gz Detector Level] 57 57 * Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hwwbackgroundlhe.pdf Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hwwbackgroundlhco.pdf Detector Level] 58 1. Top associated production %$pp \to t\bar tH$% with %$H \to b \bar b$%58 1. Top associated production $pp \to t\bar tH$ with $H \to b \bar b$ 59 59 * Signal + Background samples: 60 60 * 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] … … 85 85 86 86 87