Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Arts and Sciences


Physics and Astronomy

First Advisor

Dr. Susan Gardner


In the Standard Model (SM), the quantity baryon number (B) − lepton number (L), B − L, is perfectly conserved. Therefore, the observation of B − L violation would reveal the existence of physics beyond the SM. Traditionally, given the severe experimental constraints on |∆B| = 1 processes, B − L violation with baryons is probed via neutron-antineutron (n − ) oscillations, although this process suffers from quenching in the presence of external fields or matter.

In this dissertation, we discuss another possibility, n − conversion, in which the |∆B| = 2 process appears with an external source. We start with the Lorentz invariant B − L violating operators of lowest mass dimension and show how the appearance of constraints on the “arbitrary” phases in the discrete symmetry trans- formations help restrict the possible low energy n − transformation operators. To explain the appearance of CPT odd n − transition operators (although they eventually vanish due to the fermion anticommutation relations), we connect it to theories of self-conjugate isofermions and show that the appearance of n − oscillations cannot occur in pure Quantum Chromodynamics (QCD) in the chiral limit. We then show how n − conversion can be free from quenching and demonstrate one way how it can be connected to n − oscillations since the quarks carry electromagnetic charge. Effective field theory is utilized to find the quark-level conversion operators and to determine the coupling parameter associated with the nuclear-level conversion operators. Finally, we argue how n − conversion can provide a complementary probe to oscillation experiments. We discuss possible n − conversion proposals and explicitly show how n − conversion experiments can set limits on the scale of B − L violation.

Digital Object Identifier (DOI)