Angular and polarization observables for Majorana-mediated B decays with effective interactions
- PDF / 1,411,441 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 52 Downloads / 209 Views
Regular Article - Theoretical Physics
Angular and polarization observables for Majorana-mediated B decays with effective interactions Lucía Duarte1,a , Gabriel Zapata2 , Oscar A. Sampayo2,b 1 2
Instituto de Física, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay Instituto de Física de Mar del Plata (IFIMAR) CONICET, UNMDP Departamento de Física, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata, Argentina
Received: 22 June 2020 / Accepted: 14 September 2020 © The Author(s) 2020
Abstract We probe the effective field theory extending the Standard Model with a sterile neutrino in B meson decays at B factories and lepton colliders, using angular and polarization observables. We put bounds on different effective operators characterized by their distinct Dirac–Lorentz structure, and probe the N -mediated B decays sensitivity to these γ interactions. We define a forward–backward asymmetry AFB between the muon and photon directions for the B → μνγ decay, which allows us to separate the SM contribution from the effective lepton number conserving and violating processes, mediated by a near on-shell N . Using the most stringent constraints on the effective parameter space from Belle and BaBar we find that a measurement of the final polariza− + tion Pτ in the rare B − → − 1 2 π decays can help us infer the scalar or vector interaction content in the N production or decay vertices. We find that the B meson decays are more sensitive to scalar operators.
1 Introduction Besides the remarkable performance of the standard model (SM) of particle physics in describing nature, neutrino oscillations are currently the most compelling experimental evidence of the need to extend the SM in order to include mechanisms for neutrino mass generation. In recent years, the LHC experiments have put stringent constraints on the existence of new physics involving colored states, but still the possible extensions of the electroweak (EW) sector are far less restricted. A variety of new physics scenarios may be hidden at energies well above the EW scale, and their study is being consistently tackled by the use of the standard model effective field theory (SMEFT) [1,2]. a e-mail:
[email protected] (corresponding author)
b e-mail:
[email protected]
0123456789().: V,-vol
But also new physics might involve weakly coupled fields at the EW scale. Many models leading to neutrino masses predict the existence of sterile right-handed neutrinos with Majorana masses, as the Type I [3–7] and also the linear and inverse seesaw mechanisms. These possibly not-that-heavy degrees of freedom can be described by an EFT including them: standard model effective field theory framework extended with right-handed neutrinos (SMNEFT) [8–11], and here we concentrate on a simplified scenario with only one right-handed neutrino added [8]. The phenomenology of models extending the Type I seesaw renormalizable Lagrangian with effective interactions of higher dimension for the right-handed neutrinos are being
Data Loading...
