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AtFB meets LHC

Hewett, JoAnne L.; Shelton, Jessie; Spannowsky, Michael; Tait, Tim M.P.; Takeuchi, Michihisa


JoAnne L. Hewett

Jessie Shelton

Tim M.P. Tait

Michihisa Takeuchi


The recent Tevatron measurement of the forward-backward asymmetry of the top quark shows an intriguing discrepancy with Standard Model expectations, particularly at large tt̅ 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 5σ level is possible with roughly 60  fb-1 at √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 √s=7  TeV. We further explore the capabilities of the 7 TeV LHC to discover resonances or contact interactions which modify the tt̅ 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.


Hewett, J. L., Shelton, J., Spannowsky, M., Tait, T. M., & Takeuchi, M. (2011). AtFB meets LHC. Physical Review D, 84(5), Article 054005.

Journal Article Type Article
Publication Date Sep 7, 2011
Deposit Date Jan 25, 2012
Journal Physical Review D - Particles, Fields, Gravitation and Cosmology
Print ISSN 1550-7998
Electronic ISSN 1550-2368
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 84
Issue 5
Article Number 054005