A Fourth Neutrino and its Consequences on CP Asymmetries

Abstract

A general analysis of the consequences of including a fourth neutrino in the standard model matter content, on CP violating observables at neutrino oscillation experiments, is presented. Neutrino oscillations in vacuum and with matter effects are studied. For the former we update and generalize previous studies on CP asymmetries with an additional active neutrino using an updated fit of the PMNS mixing matrix. We study the values of the new CP violating phases which maximize the different CP asymmetries in T2K and MINOS-like setups aiming to elucidate if the new phases yield measurable effects in the most favorable case. We show that due to a combined effect of kinematics and unitarity it is possible to obtain an observable asymmetry in the survival channels without violating CPT. For the MINOS-like setup, we find maximum asymmetries in vacuum of the order of 2% and 4% for the ${\nu }_{\mu }\to {\nu }_e$ and ${\nu }_e\to {\nu }_{\tau }$ channels respectively. For the T2K-like setup we obtain maximum asymmetries of the order of 6% in the survival ${\nu }_{\mu }\to {\nu }_{\mu }$ channel. Tree level matter effects enhance the former reaching asymmetries of the order of 10% for the ${\nu }_{\mu }\to {\nu }_e$ and ${\nu }_e\to {\nu }_{\tau }$ channels, while the ${\nu }_{\mu }\to {\nu }_{\mu }$ survival channel changes slightly depending on the mass hierarchy. Box diagrams with the fourth mass eigenstate as a virtual particle were also considered, the corrections to the scattering amplitude being negligible.

arXiv comment12 pages, 9 figures

References in corpus (27)

• Observation of electron-antineutrino disappearance at Daya Bay
• Observation of Reactor Electron Antineutrino Disappearance in the RENO Experiment
• Evidence for Neutrino Oscillations from the Observation of Electron Anti-neutrinos in a Muon Anti-Neutrino Beam
• Indication of Electron Neutrino Appearance from an Accelerator-produced Off-axis Muon Neutrino Beam
• The Reactor Antineutrino Anomaly
• Event Excess in the MiniBooNE Search for ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$ Oscillations
• Four Generations and Higgs Physics
• Improved Measurement of Electron Antineutrino Disappearance at Daya Bay
• Quarks and Leptons Beyond the Third Generation
• Non-Standard Neutrino Interactions with Matter from Physics Beyond the Standard Model
• Updated Status of the Global Electroweak Fit and Constraints on New Physics
• Four Statements about the Fourth Generation
• On the Treatment of Neutrino Oscillations Without Resort to Weak Eigenstates
• First Measurement of θ_13 from Delayed Neutron Capture on Hydrogen in the Double Chooz Experiment
• Search for heavy bottom-like quarks in 4.9 inverse femtobarns of pp collisions at sqrt(s) = 7 TeV
• Four Generations, the Electroweak Phase Transition, and Supersymmetry
• Search for heavy, top-like quark pair production in the dilepton final state in pp collisions at sqrt(s) = 7 TeV
• Mass of the higgs versus fourth generation masses
• Search for heavy bottom-like quarks decaying to an electron or muon and jets in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV
• Source of CP Violation for the Baryon Asymmetry of the Universe
• Search for down-type fourth generation quarks with the ATLAS detector in events with one lepton and hadronically decaying W bosons
• Search for pair-produced heavy quarks decaying to Wq in the two-lepton channel at sqrt(s) = 7 TeV with the ATLAS detector
• Search for pair production of a heavy up-type quark decaying to a W boson and a b quark in the lepton+jets channel with the ATLAS detector
• Search for a fourth generation t' quark in ppbar collisions at sqrt{s}=1.96 TeV
• Electroweak phase transition in the MSSM with four generations
• Exact and Approximate Formulas for Neutrino Mixing and Oscillations with Non-Standard Interactions
• Dynamical Symmetry Breaking With a Fourth Generation

Cited by in corpus (1)

• The Phenomenology of Right Handed Neutrinos