Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-07-08
Abstract： A flavor-nonuniversal chiral color model is introduced. It is used for comparison to the recent data on (p) over barp -> (t) over bart. We concluded that the data are consistent with interpretation as an axigluon exchange within 1 sigma and a unique rise and fall behavior is predicated with regard to the asymmetry A(FB)(t) as a function of t (t) over bar invariant mass, which can distinguish our model from others before one discovers the axigluon resonance. Further aspects of the model are discussed. (C) 2009 Elsevier B.V. All rights reserved.
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Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-07-08
Abstract： We consider the recent measurement of the top quark forward-backward asymmetry at the Fermilab Tevatron, which shows a discrepancy of slightly more than 2 sigma compared to the standard model prediction. We find that t-channel exchange of a color sextet or triplet scalar particle can explain the measurement, while leaving the cross section for t (t) over bar production within measured uncertainties. Such particles have good discovery prospects by study of the kinematic structure of t (t) over bar + jets at the LHC.
Peer Review Status:Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-07-05
Abstract： We propose a gauged Ud(1)(H) horizontal symmetry around a TeV scale that is a subgroup of a SU(3)(H) horizontal gauge symmetry broken at O(10(14)) GeV. The breaking generates right-handed Majorana neutrino masses through a SU(3)(H) sextet scalar. A particular Majorana right-handed neutrino mass matrix explicitly determines the remnant U(1)(H) at low energy which only couples to b - s and mu - tau in the gauge eigenstate. The dangerous K - (K) over bar, D - (D) over bar mixing and B-s -> mu(+) mu(-) are kept to be safe because the relevant couplings are suppressed through high powers of small mixing angles in the fermion rotation matrix. Our analysis which applies to the general case shows that the Tevatron di-muon anomaly can be explained through the B-s and B-d mixing while keeping all the other experimental constraints within 90% C.L. For the B meson decay, the B-s -> mu(+/-) tau(-/+) is the leading leptonic decay channel which is several orders of magnitude below current experimental bounds.
Peer Review Status:Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-07-05
Abstract： The improved standard model prediction for total top quark forward-backward asymmetry of 8.9% at the Tevatron has significantly reduced the long-term discrepancy between the theory value and the experimental observations. The seemingly "last" over-3 sigma anomaly is the CDF measurement of A(FB)(M-t (t) over bar > 450 GeV) and it is not seen by the D0 Collaboration. In this paper, we take the CDF measurement to obtain the best-fit parameter space for various previously proposed models, including axigluon, t-channel neutral current, charged current, and diquark models, then study the predictions of the corresponding parameter space on the direct search or indirect constrain. The particular axigluon model is excluded by the LHC dijet search. The t-channel Z' model suffer from the Tevatron same-sign dilepton search bound. The t-channel W' model and the diquark model both predict significant increase in the production rate of inclusive t (t) over bar search at the LHC which is not seen. We conclude none of the models are favored by the direct search bound.
Peer Review Status:Awaiting Review
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