Combined analysis of Z'-->tt and Z'-->ttj production for vector resonance searches at LHC
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AutorÁguila Giménez, Francisco del; Aguilar-Saavedra, Juan Antonio; Moretti, M.; Piccinini, F.; Pittau, Roberto; Treccani, M.
LHC (Large Hadron Collider)
Águila, F.; et al. Combined analysis of Z'-->tt and Z'-->ttj production for vector resonance searches at LHC. Physics Letters B, 685(4-5): 302-308 (2010). [http://hdl.handle.net/10481/30588]
PatrocinadorThis work has been partially supported by MICINN (FPA2006-05294), by Junta de Andalucía (FQM 101, FQM 437 and FQM 03048), and by the European Community's Marie-Curie Research Training Network under contract MRTN-CT-2006-035505 “Tools and Precision Calculations for Physics Discoveries at Colliders”. The work of J.A.A.S. and M.T. has been supported by MICINN Ramón y Cajal and Juan de la Cierva contracts, respectively. F.P. and M.M. acknowledge warm hospitality and partial support from CERN, Physics Department, TH Unit, during the completion of this work.
We have implemented a code for Z' + n jets production in ALPGEN, with Z' decays into several final states, including l+ l- and t tbar. The MLM prescription is used for matching the matrix element with the parton shower, including in this way the leading soft and collinear corrections. In order to demonstrate its capabilities, we perform a combined analysis of Z' -> t tbar and Z' -> t tbar j production for a heavy leptophobic gauge boson. It is found that the effect of the extra jet cannot only be accounted for by a K factor multiplying the leading-order cross section. In fact, the combined analysis for Z' -> t tbar and Z' -> t tbar j presented improves the statistical significance of the signal by 25% (8.55 sigma versus 6.77 sigma for a Z' mass of 1 TeV), compared with the results of an inclusive analysis carried out on the same sample of t tbar + t tbar j events.