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Title: Explaining the t - t¯ asymmetry with a light axigluon

We propose an axigluon with mass between 400 and 450 GeV and flavor-universal couplings to quarks to explain the Tevatron t -t¯ forward-backward asymmetry. The model predicts a small negative asymmetry for t - t¯ pairs with invariant mass below 450 GeV and a large positive asymmetry above 450 GeV. The asymmetry arises from interference between s-channel gluon and axigluon diagrams and requires a relatively weakly coupled axigluon (ga=gqcd/3). Axigluon-gluon interference does not contribute to the t - t¯ cross section. New contributions to the cross section arise only at fourth order in the axigluon coupling and are very small for a sufficiently broad axigluon. Dijet measurements do not significantly constrain the axigluon couplings. We propose several possible UV completions of the phenomenological axigluon which explain the required small couplings and large width. Such UV completions necessarily contain new colored fermions or scalars below the axigluon mass and predict multijet events with large cross sections at the Tevatron and LHC.
Authors:
;
Publication Date:
OSTI Identifier:
1100745
Type:
Publisher's Accepted Manuscript
Journal Name:
Physical Review. D, Particles, Fields, Gravitation and Cosmology
Additional Journal Information:
Journal Volume: 84; Journal Issue: 5; Journal ID: ISSN 1550-7998
Publisher:
American Physical Society
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English