A general analysis of Wtb anomalous couplings

• 来源期刊: 中国物理C（英文版）
• 年，卷（期）: 2017,（6）
• 页码范围: 11-32
• 页数: 22页
• 语种: 英文
• DOI: 10.1088/1674-1137/41/6/063101

摘要

We investigate new physics effects on the Wtb effective couplings in a model-independent framework.The new physics effects can be parametrized by four independent couplings,f1L,f1R,f2L and f2R.We further introduce a set of parameters xo,xm,xp and x5 which exhibit a linear relation to the single top production cross sections.Using recent data for the t-channel single top production cross section σt,tW associated production cross section σtw,s-channel single top production cross section σs,and W-helicity fractions F0,FL and FR collected at the 8 TeV LHC and Tevatron,we perform a global fit to impose constraints on the top quark effective couplings.Our global fitting results show that the top quark effective couplings are strongly correlated.We show that (i) improving the measurements of σt and σtw is important in constraining the correlation of (f1R,f2R) and (f2L,f2R);(ii) f1L and f2R are anti-correlated,and are sensitive to all the four experiments;(iii) f1R and f2L are also anti-correlated,and are sensitive to the F0 and FL measurements;(iv) the correlation between f2L and f2R is sensitive to the precision of the σt,σtw and F0 measurements.The effective Wtb couplings are studied in three kinds of new physics models:the G(221) =SU(2)1 (⊕)SU(2)2 (⊕) U(1)x models,the vector-like quark models and the Littlest Higgs model with and without T-parity.We show that the Wtb couplings in the left-right model and the un-unified model are sensitive to the ratio of gauge couplings when the new heavy gauge boson's mass (Mw') is less than several hundred GeV,but the constraint is loose if Mw'＞ 1 TeV.Furthermore,the Wtb couplings in vector-like quark models and the Littlest Higgs models are sensitive to the mixing angles of new heavy particles and SM particles.