Changes between Version 1 and Version 2 of FourFermionttll

Timestamp:

Jan 25, 2022, 11:36:52 PM (4 years ago)

Author:

Yoav Afik

Comment:

--

FourFermionttll

@@ -1 @@
- 
+== 4-fermion EFT ttll (l=e,mu)
+
+== Authors:
+* Yoav Afik (yoavafik@campus.technion.ac.il) (1)
+* Shaouly Bar-Shalom (shaouly@physics.technion.ac.il) (2)
+* Kuntal Pal (3)
+* Amarjit Soni (4)
+* Jose Wudka (3)
+
+(1) Experimental Physics Department, CERN, Geneva, Switzerland
+
+(2) Department of Physics, Technion: Israel Institute of Technology Haifa, Israel
+
+(3) Department of Physics, University of California, Riverside, CA, US
+
+(4) Department of Physics, Brookhaven National Laboratory, Upton, NY, US
+
+== Description of the model:
+This is a Contact Interaction model with t-t-l-l terms, for scalar, vector and tensor couplings. The effective Lagrangian of the model is described by:
+
+{{{ 
+#!latex 
+\begin{align*}
+{\cal L}_{tt\ell \ell} =  {1\over\Lambda^2} \sum_{i,j=L,R} \biggl[ V_{ij}^\ell \left({\bar \ell} \gamma_\mu P_i \ell \right) \left( \bar t \gamma^\mu P_j t \right)  + S_{ij}^\ell \left( {\bar \ell} P_i \ell \right) \left( \bar t P_j t \right)  + T_{ij}^\ell \left( {\bar \ell} \sigma_{\mu \nu} P_i \ell \right) \left( \bar t \sigma_{\mu \nu} P_j t \right) \biggr] ~.
+\end{align*}
+}}} 
+
+
+
+
+
+== Model Files:
+* [https://feynrules.irmp.ucl.ac.be/attachment/wiki/FourFermionFCNCtqll/4fermion-tqll-models.zip 4fermion-tqll-models.zip] : the full model both at the 4FS and at the 5FS. In the paper we use the 5FS.
+* Please note there are four models: t-u-l-l Contact Interactions at the 4FS / 5FS, and t-c-l-l Contact Interactions at the 4FS / 5FS.
+
+== Commands for MadGraph5_aMC@NLO, for a production of a muon and an anti-muon with a top quark and up to one more jet (NP only):
+{{{
+define p = g u c d s b u~ c~ d~ s~ b~ 
+define j = g u c d s b u~ c~ d~ s~ b~ 
+generate p p > mu+ mu- t t~ NP^2==4
+add process p p > mu+ mu- t t~ j NP^2==4
+...
+set lambdas...
+set fSrr ...
+set fTrr ...
+set fVlr ...
+set fVrl ...
+set fVrr ...
+set fVll ...
+}}}
+For the scenario of vector coupling, interference with the SM should be considered. This can be done by changing the coupling order in the generation commands:
+{{{
+...
+generate p p > mu+ mu- t t~ NP^2==2
+add process p p > mu+ mu- t t~ j NP^2==2
+...
+}}}
+
+Where lambdas is the scale of new physics in GeV, fSrr is the coupling of the t-u-l-l scalar operator with right-right chirality of the fermions, etc. For example, if we set fSrr=1 and all other couplings to 0, we get a scalar operator with:
+{{{ 
+#!latex 
+\begin{align*}
+{\cal L}_{t\bar t\ell \ell} =  {1\over\Lambda^2} \left( {\bar \ell} P_R \ell \right) \left( \bar t P_R t \right) ~.
+\end{align*}
+}}} 
+
+
+Note that only operators with the couplings fSrr, fTrr, fVlr, fVrl, fVrr, fVll are generated by this UFO.
+
+
+== References:
+[1] Afik, Yoav and Bar-Shalom, Shaouly and Pal, Kuntal and Soni, Amarjit and Wudka, Jose. 2111.13711.
+ * Link to paper: https://arxiv.org/abs/2111.13711