Identifying physics beyond SMEFT in the angular distribution of $Λ_b\rightarrow Λ_c(\rightarrowΛπ)τ\barν_τ$ decay
Year: 2023
Type: preprint
Abstract: In the Standard Model Effective Field Theory (SMEFT), the $SU(2)_L\times U(1)_Y$ symmetry of the Standard Model is linearly realized. However, it is possible that more general effective field theories, such as the Higgs Effective Field Theory (HEFT) where this symmetry is realized non-linearly, are needed to describe the data. Identifying physics beyond SMEFT could shed light on the nature of Higgs and the realization of the electroweak symmetry. We explore the possibility of such an identification by studying the effects of scalar and vector new-physics operators on the angular distribution of $Λ_b\rightarrow Λ_c(\rightarrowΛπ)τ\barν_τ$. This decay is sensitive to the 6-dimensional effective operator $O_V^{LR}\equiv(\barτγ^μP_Lν_τ)(\bar{c}γ_μP_R b)$, which is present in HEFT but suppressed in SMEFT. We identify the angular observables that can have significant contributions from $O_V^{LR}$, and hence would be useful for probing not only BSM physics but also physics beyond SMEFT. We further find that constraining the branching ratio of $B_c\rightarrow τ\bar ν_τ$ would be crucial for performing this task.
Source: arXiv (Cornell University)
Institution: Tata Institute of Fundamental Research
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1049003178, G680876163
OpenAlex ID: W4378501424