Browsing by Author "Sharma, Pankaj"
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- New physics contributions to A(FB)(t(t)over-bar) at the TevatronPublication . Biswal, Sudhansu S.; Mitra, Subhadip; Santos, Rui; Sharma, Pankaj; Singh, Ritesh K.; Won, MiguelThe Tevatron has measured a discrepancy relative to the standard model prediction in the forward-backward asymmetry in top quark pair production. This asymmetry grows with the rapidity difference of the two top quarks. It also increases with the invariant mass of the t (t) over bar pair, reaching, for high invariant masses, 3.4 standard deviations above the next-to-leading order prediction for the charge asymmetry of QCD. However, perfect agreement between experiment and the standard model was found in both total and differential cross section of top quark pair production. As this result could be a sign of new physics we have parametrized this new physics in terms of a complete set of dimension six operators involving the top quark. We have then used a Markov chain Monte Carlo approach in order to find the best set of parameters that fits the data, using all available data regarding top quark pair production at the Tevatron. We have found that just a very small number of operators are able to fit the data better than the standard model.
- Optimising charged Higgs boson searches at the Large Hadron Collider across b(b)over-barW(+/-) final statesPublication . Moretti, Stefano; Santos, Rui; Sharma, PankajIn the light of the most recent data from Higgs boson searches and analyses, we re-assess the scope of the Large Hadron Collider in accessing heavy charged Higgs boson signals in b¯bW±final states, wherein the contributing channels can be H+→t¯b, hW±, HW±and AW±. We consider a 2-Higgs Doublet Model Type-II and we assume as production mode bg→tH−+c.c., the dominant one over the range MH±≥480GeV, as dictated by b →sγconstraints. Prospects of detection are found to be significant for various Run2 energy and luminosity options.
- Signal to background interference in pp -> tH( -)-> tW( - )b(b)over-bar at the LHC Run IIPublication . Arhrib, Abdesslam; Benbrik, Rachid; Moretti, Stefano; Santos, Rui; Sharma, PankajWe investigate in the Large Hadron Collider (LHC) environment the possibility that sizeable interference effects between a heavy charged Higgs boson signal produced via bg -> tH(-) (+c.c.) scattering and decaying via H--> W(-)A -> W- b(b)over-bar (+c.c.) and the irreducible background given by bg -> tW(-) b(b)over-bar topologies could spoil current search approaches where the former and latter channels are treated separately. The rationale for this comes from the fact that a heavy charged Higgs state can have a large width, which can also happen for the CP-odd neutral Higgs state emerging in the ensuing decays, which in turn enables such interferences. We conclude that effects are very significant, both at the inclusive and exclusive level (i.e., both before and after H-+/- selection cuts arc enforced, respectively) and typically of a destructive nature. This, therefore, implies that currently established LHC reaches for heavy charged Higgs bosons require some level of resealing. However, this is possible a posteriori, as the aforementioned H-+/- selection cuts shape the interference contributions at the differential level in a way similar to that of the isolated H-+/- signal, so there is no need to reassess the efficiency of the individual cuts. We show such effects quantitatively by borrowing benchmark points from different Yukawa types of a 2-Higgs doublet model parameter space for H-+/- values starting from around 200 GeV.