Model independent analysis of the forward–backward asymmetry of top quark production at the Tevatron

112

111

Abstract:We examine the implications of the recent CDF measurement of the top-quark forward-backward asymmetry, focusing on a scenario with a new color octet vector boson at 1-3 TeV. We study several models, as well as a general effective field theory, and determine the parameter space which provides the best simultaneous fit to the CDF asymmetry, the Tevatron top pair production cross section, and the exclusion regions from LHC dijet resonance and contact interaction searches. Flavor constraints on these models are more subtle and less severe than the literature indicates. We find a large region of allowed parameter space at high axigluon mass and a smaller region at low mass; we match the latter to an SU(3) 1 × SU(3) 2 /SU(3) c coset model with a heavy vector-like fermion. Our scenario produces discoverable effects at the LHC with only 1 − 2 fb −1 of luminosity at √ s = 7 − 8 TeV. Lastly, we point out that a Tevatron measurement of the b-quark forwardbackward asymmetry would be very helpful in characterizing the physics underlying the top-quark asymmetry.

Section: Jhep03(2011)003mentioning

confidence: 99%

LHC predictions from a tevatron anomaly in the top quark forward-backward asymmetry

Bai

Hewett

Kaplan

et al. 2011

112

111

“…We interpret the discrepancy between the Tevatron A tt FB data and the SM expectations as originating from heavy NP. (For previous relevant works see [11][12][13][14][15][16], and for a review of various NP models see e.g. [17].)…”

Section: Jhep12(2012)053mentioning

confidence: 99%

Predictions from heavy new physics interpretation of the top forward-backward asymmetry

Delaunay

Gedalia

Hochberg

et al. 2012

We derive generic predictions at hadron colliders from the large forwardbackward asymmetry observed at the Tevatron, assuming the latter arises from heavy new physics beyond the Standard Model. We use an effective field theory approach to characterize the associated unknown dynamics. By fitting the Tevatron tt data we derive constraints on the form of the new physics. Furthermore, we show that heavy new physics explaining the Tevatron data generically enhances at high invariant masses both the top pair production cross section and the charge asymmetry at the LHC. This enhancement can be within the sensitivity of the 8 TeV run, such that the 2012 LHC data should be able to exclude a large class of models of heavy new physics or provide hints for its presence. The same new physics implies a contribution to the forward-backward asymmetry in bottom pair production at low invariant masses of order a permil at most.

“…Some comparative studies between them have been performed, too [29][30][31]. In addition, there exist several analyses in terms of effective operators, which are valid only for heavy new physics [6,[32][33][34][35][36]. The effective Lagrangian can, under the assumption of decoupling new physics, be derived from the direct description in terms of extra fields, as done explicitly in Ref.…”

Section: Introductionmentioning

confidence: 99%

Simple models for the top asymmetry: constraints and predictions

Aguilar-Saavedra

Pérez-Victoria

2011

106

We perform a comprehensive study of the allowed range for the Tevatron tt forward-backward asymmetries in six representative new physics models: a flavour-changing Z ′ boson, a scalar isodoublet, a W ′ boson, a heavy axigluon, a colour-triplet and a colour-sextet scalar. We devote special attention to the constraints from the tt tail at LHC on the parameter space, which will be dramatic if the measurements agree with the Standard Model prediction, specially for Z ′ and W ′ bosons. We also study the predictions for the charge asymmetries at LHC and compare several proposed definitions.