Probing physics beyond the standard model through neutrino-electron scatterings

Bilmiş, Selçuk
Neutrino interactions are well explained with the electroweak theory. Hence, as an alternative to collider experiments, new physics can be searched in neutrino exper iments as well. Using the neutrino-electron scattering data taken by several experi ments (TEXONO, GEMMA, LSND, CHARM II, BOREXINO), which were chosen according to their incoming neutrino energy as well as recoil energy of the electron, possible effects on the neutrino scattering data originating from the presence of non commutativity in space as well as the existence of a hidden sector in the form of dark photon have been studied. Once QED is extended into non-commutative space, coupling of neutral particles to photons becomes possible at tree level. Using this new vertex, contribution to the cross section is calculated and bounds for the non-commutative energy scale ΛNC are set. We find that the results from CHARM II experiments give the stringent bounds as ΛNC > 3.3 TeV at 95% confidence level and improve the bounds over the colliderexperiments. In the second part of the thesis, as an alternative scenario, the effects of the hidden sector through a light gauge boson A0, associated with a group U(1)B−L is searched in the neutrino electron scattering experiments. This new gauge boson can interact with neutrinos at tree level even though it has no charge, hence named as dark photon. The bounds are set for the mass of the dark photon mA0 and the coupling constant gB−L. The exclusion plot at the 90% C.L. for the mA0− gB−L plane is plotted. It is shown that the interference term can not be neglected and improves the bounds. Our results provide more stringent bounds to some regions of the parameter space.
Citation Formats
S. Bilmiş, “Probing physics beyond the standard model through neutrino-electron scatterings,” Ph.D. - Doctoral Program, Middle East Technical University, 2016.