#### Alladi Ramakrishnan Hall

#### Fully constrained neutrino mass matrices and how to model them.

#### Krishnan Rama

##### The School of Good Shepard

*We discuss a set of Majorana neutrino mass matrices which are fully constrained (without free parameters). They result in the reactor mixing angle, sin^2(theta_13) = 2/3 sin^2(pi/16) and the neutrino mass ratios, m_1:m_2:m_3 = sqrt(2)tan(3pi/16):1:sqrt(2)tan(5pi/16), consistent with the neutrino oscillation data. We introduce a framework of model building using the discrete group, Sigma(72x3), to construct such fully constrained mass matrices. The Majorana mass matrix having six complex degrees of freedom is mapped into a flavon field transforming as a complex sextet under Sigma(72x3). We propose to define the flavon vacuum alignment entirely in terms of the residual symmetries of Sigma(72x3) and an additional group.*

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