| Article | |
| Report number | arXiv:2111.07421 ; UdeM-GPP-TH-21-290 |
| Title | Beyond the standard model effective field theory with $B \rightarrow c \tau^- \overline{\nu}$ |
| Related title | Beyond SMEFT with $b \to c \,\tau^- {\bar\nu}$ |
| Author(s) | Burgess, C.P. (McMaster U. ; Perimeter Inst. Theor. Phys. ; CERN) ; Hamoudou, Serge (Montreal U.) ; Kumar, Jacky (Montreal U. ; TUM-IAS, Munich) ; London, David (Montreal U.) |
| Publication | 2022-04-01 |
| Imprint | 2021-11-14 |
| Number of pages | 7 |
| Note | 6 pages, 1 figure. Changes: a few oversights corrected (thanks to Christopher Murphy), conclusions unchanged. Mar. 29: references added |
| In: | Phys. Rev. D 105 (2022) 073008 |
| DOI | 10.1103/PhysRevD.105.073008 (publication) |
| Subject category | hep-ph ; Particle Physics - Phenomenology |
| Abstract | Electroweak interactions assign a central role to the gauge group $SU(2)_L \times U(1)_Y$, which is either realized linearly (SMEFT) or nonlinearly (e.g., HEFT) in the effective theory obtained when new physics above the electroweak scale is integrated out. Although the discovery of the Higgs boson has made SMEFT the default assumption, nonlinear realization remains possible. The two can be distinguished through their predictions for the size of certain low-energy dimension-6 four-fermion operators: for these, HEFT predicts $O(1)$ couplings, while in SMEFT they are suppressed by a factor $v^2/\Lambda_{\rm NP}^2$, where $v$ is the Higgs vev. One such operator, $O_V^{LR} \equiv ({\bar \tau} \gamma^\mu P_L \nu )\, ( {\bar c} \gamma_\mu P_R b )$, contributes to $b \to c \,\tau^- {\bar\nu}$. We show that present constraints permit its non-SMEFT coefficient to have a HEFTy size. We also note that the angular distribution in ${\bar B} \to D^* (\to D \pi') \, \tau^{-} (\to \pi^- \nu_\tau) {\bar\nu}_\tau$ contains enough information to extract the coefficients of all new-physics operators. Future measurements of this angular distribution can therefore tell us if non-SMEFT new physics is really necessary. |
| Copyright/License | preprint: (License: CC BY 4.0) publication: © 2022-2025 authors (License: CC BY 4.0), sponsored by SCOAP³ |
Corresponding record in: Inspire
Zapis kreiran 2021-11-17, zadnja izmjena 2023-01-31
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