[Paper Review] Neutrino Majorana

S. M. Bilenky|arXiv (Cornell University)|May 15, 2006

Neutrino Physics Research4 citations

TL;DR

This paper reviews Majorana's seminal 1937 paper on the symmetric treatment of electrons and positrons and examines the current theoretical status of Majorana neutrinos—fermions that are their own antiparticles. It establishes the conceptual foundation for why neutrinos might be Majorana particles, a key hypothesis in beyond-Standard Model physics with implications for lepton number violation and neutrinoless double beta decay.

ABSTRACT

The Majorana paper ``Symmetrical theory of the electron and positron'' is briefly reviewed. The present status of Majorana neutrinos is discussed.

Motivation & Objective

• To revisit and interpret Majorana's 1937 symmetric theory of electrons and positrons.
• To assess the theoretical and phenomenological status of neutrinos as Majorana particles.
• To explore the implications of Majorana neutrinos for fundamental symmetries and lepton number conservation.
• To provide a conceptual framework for ongoing research into neutrino mass generation and lepton number violation.

Proposed method

• Analyzes the original Majorana paper's formulation of a relativistic field theory with symmetric electron and positron states.
• Applies the Majorana condition to the neutrino field, requiring ψ = ψ^c (field equals its charge conjugate).
• Reviews the implications of the Majorana condition for fermion statistics and mass generation.
• Discusses the role of the Majorana mass term in the Lagrangian, which violates lepton number by two units.
• Examines the theoretical consistency of Majorana neutrinos within quantum field theory and their potential detection via neutrinoless double beta decay.
• Compares Majorana and Dirac neutrino scenarios in the context of the Standard Model extension.

Experimental results

Research questions

• RQ1 Can the symmetric treatment of particles and antiparticles in Majorana's theory be consistently applied to neutrinos?
• RQ2 What are the theoretical and phenomenological consequences of assuming neutrinos are their own antiparticles?
• RQ3 How does the Majorana mass term differ from the Dirac mass term in the context of neutrino field theory?
• RQ4 What experimental signatures would confirm that neutrinos are Majorana particles?
• RQ5 What is the current theoretical consensus on the viability of Majorana neutrinos in extensions of the Standard Model?

Key findings

• Majorana's symmetric theory provides a consistent framework for describing fermions that are their own antiparticles.
• The Majorana condition leads to a real mass term in the Lagrangian, distinct from the complex mass term in Dirac theory.
• Majorana neutrinos violate lepton number by two units, offering a mechanism for neutrino mass generation beyond the Standard Model.
• The existence of Majorana neutrinos is a key prediction of theories such as the seesaw mechanism.
• Neutrinoless double beta decay is the primary experimental signature for testing the Majorana nature of neutrinos.
• Theoretical consistency of Majorana neutrinos remains robust within quantum field theory, though experimental confirmation is still lacking.