A(FB)(t) meets LHC

作者：Hewett JoAnne L^*; Shelton Jessie; Spannowsky Michael; Tait Tim M P; Takeuchi Michihisa

来源：Physical Review D - Particles, Fields, Gravitation and Cosmology, 2011, 84(5): 054005.

DOI：10.1103/PhysRevD.84.054005

The recent Tevatron measurement of the forward-backward asymmetry of the top quark shows an intriguing discrepancy with Standard Model expectations, particularly at large t (t) over bar invariant masses. Measurements of this quantity are subtle at the LHC, due to its pp initial state, however, one can define a forward-central-charge asymmetry which captures the physics. We study the capability of the LHC to measure this asymmetry and find that within the SM a measurement at the 5 sigma level is possible with roughly 60 fb(-1) at root s = 14 TeV. If nature realizes a model which enhances the asymmetry (as is necessary to explain the Tevatron measurements), a significant difference from zero can be observed much earlier, perhaps even during early LHC running at root s = 7 TeV. We further explore the capabilities of the 7 TeV LHC to discover resonances or contact interactions which modify the t (t) over bar invariant mass distribution using recent boosted top-tagging techniques. We find that TeV-scale color-octet resonances can be discovered, even with small coupling strengths and that contact interactions can be probed at scales exceeding 6 TeV. Overall, the LHC has good potential to clarify the situation with regards to the Tevatron forward-backward measurement.

• 出版日期2011-9-7