Simon Peter Rosen

Effects of Light and Heavy Majorana Neutrinos in Neutrinoless Double Beta Decay

Abstract We examine interference effects between the light neutrino and the heavy neutral lepton exchange amplitudes in neutrinoless double beta [(ββ) 0 ν ] decay. Using the lower limit on the electron neutrino mass deduced from the tritium end point measurements and the most recent data on neutrinoless double beta decay of tellurium, we obtain an upper limit on the mass of the heavy neutral lepton of about 3 GeV. We also find that the effective Majorana mass parameter associated with the (ββ) 0 ν -decay exhibits a strong dependence on the parent nuclear species, and therefore searches for the (ββ) 0 ν -decay should be performed for several nuclei simultaneously and independently.

Are neutrons always left-handed?

Abstract We explore the possibility of using neutral weak interactions to see whether neutrinos may flip their helicity. Experiments ranging from low-energy neutrino-nucleus scattering to high-energy inclusive reactions are discussed as tests for the presence of helicity-flipping scalar, pseudoscalar and tensor interactions.

Testing the Muon Number Conservation Law in ν̄ μ + e- Interactions at High Energies

We propose to test the validity of the multiplicative muon number conservation law by comparing the quasi-elastic reactions ν μ + e- → μ - + νe and ν μ + e- → μ - + νe at Fermi-Lab energies. We note that the measured electron spectrum in muon decay places strong constraints on the effective Lagrangian for the ν μ -inducted process.

W-exchange dominance in neutral B-meson decay

Tests of W-exchange dominance in neutral B-meson decay are developed from the isospin and SU(3) properties of the final state. For B0 (d), it is shown that the decay rates into (D+ plus anything) and into (F+ plus anything) are always equal to one another and never more than 32 times the rate for (D0 plus anything). A similar analysis is applied to B0(s), and it is suggested that any of the four possibilities {;ψ, ηc}+(φ, η′) would make a good signal for this meson.

Symmetries and conservation laws in neutrino physics

The basic conservation laws of neutrino physics are described, and the experimental limits on their validity are discussed. The best limit comes from double beta decay, and it shows that lepton number and helicity are conserved in charged weak current processes to order 3 × 10−4. No such limits are available for the recently discovered neutral currents, and so the speculation is made that there may be a large breakdown of the usual helicity rule for neutrinos in neutral current interactions. Experiments to test this speculation are suggested in neutrino scattering off various targets, in neutral beta decay, and in pseudoscalar meson decay. The roles of iso‐spin and strangeness in neutral currents are also discussed. Predictions based upon lepton conservation and helicity are made for the decay distributions of heavy leptons.