Single B production with decays to Z, H and 3rd generation SM quarks¶
Here we consider an effective model , where as a generic framework the four VLQ states X, T, B and Y are added as new coloured spin-1/2 objects to the SM, embedded in complete \(SU(2)_L\) representations. They have fixed electric charge and can only decay to SM quarks in association with the production of W, Z or Higgs bosons. We use the UFO file (without the chromomagnetic extension) provided at http://feynrules.irmp.ucl.ac.be/wiki/VLQ , read into Herwig 7.1.2 to study the single production of B VL quarks, under the following assumptions:
- the VLQ only couples to the third generation quarks of the SM.
- the X, Y and Y masses are so high (10 TeV) they are effectively decoupled
- the coupling of the B to the W boson is zero; thus all decays involve the Z or H, and we scan the branching fraction \(0 < \xi_H = 1 - \xi_Z < 1\).
All 7, 8 and 13 TeV from ATLAS and CMS available in rivet as of 29/3/2018 are used.
As more 8 TeV measurements are currently available than 13 TeV, most of the sensitivity comes from there, although 7 and 13 TeV do contribute significantly.
In the lower reaches of the plot, where Z decays of the B dominate, the most important measurements are the differential cross sections involve dilepton pairs near the Z mass, especially  and those in association with b-jets, especially . In the upper region, decays to a Higgs dominate and the most sensitive measurements are the \(H \rightarrow \gamma\gamma\) fiducial cross sections, especially .
Jack Burton, Jon Butterworth, Ben Waugh, David Yallup