Research Projects

The discovery of neutrinos bring in a lot of surprises in particle physics. At the time neutrinos were theorised to be electrically neutral massless particles. The discovery of neutrino oscillation snatches the masslessness of neutrinos, it created a dent in the adamantine success of the standard model (SM) of particle physics. Neutrinos are purely left-handed fermionic fields residing in the SU(2) doublet and principles of gauge invariance prohibit mass terms for the neutrinos at the renormalisable level. Clearly, this calls for physics beyond the SM (BSM). Popular seesaw models can explain the neutrino masses. However, an experimental verification of any of the proposed neutrino mass models is yet to come. Also, while the oscillation experiments tell us a lot about the mixing properties and the mass-squared differences of the neutrinos, it remains mute about the exact masses of the neutrinos. The beta-decay experiments are striving to determine the exact masses of neutrinos. Apart from mass scale there are other properties of neutrinos which are equally obscure. Exploring these aspects of neutrinos are going to be the basis of this current project. Neutrinos also play an equally significant role in cosmology. The standard model of cosmology is the ΛCDM model. The discovery of cosmic microwave background (CMB) and future refined measurements by COBE, WMAP, and Planck help us understand the evolution of our Universe. Along with CMB this theory also predicts the existence of a cosmic neutrino background (CNB). According to the ΛCDM, the neutrinos decoupled from other particles and formed CNB earlier (~1s after the Big Bang) than the CMB photons (~400k yrs). Here lies the importance of CNB, a detailed study of Big Bang Nucleosynthesis and CMB give information of the early Universe at a few minutes old and ~400k years old, respectively, on the other hand observation of CNB allows us to study the early Universe at ~1s old. The contribution of the CNB neutrinos in the energy density of the Universe affects the light element abundances during BBN and leaves its footprints in the CMB anisotropies, and structure formation. However, due to the tiny masses, small interaction cross sections and, low temperature of the CNB today (~1.95 K) it is extremely difficult to detect them directly. Based on a proposal by Weinberg, the PTOLEMY experiment has been proposed to detect CNB neutrinos by capturing electron neutrinos on a 100 g tritium target via the neutrino capture process. In this respect other experiments which are trying to measure the exact neutrino mass can also be of immense help. A few such ongoing and upcoming experiments are KATRIN, ECho, HOLMES, Project-8 etc. In this project we want to study the CNB and its detection prospects in these experiments vis-a-vis some fundamental properties of neutrinos like their masses, magnetic moments, decay, and decoherence in their oscillation.