Using the Pontecorvo relations, a QFT analog for the "flavor" form of this operator sets it equal to a sinusoid of the mixing angle.  
Using the Pontecorvo relations, a QFT analog for the "flavor" form of this operator sets it equal to a sinusoid of the mixing angle.  The eigenfunctions of this operator have a normalization constant of the exponential of negative one-half times the eigenvalue squared. In Wick ordering, this operator is placed on the right. The square of this operator multiplies e to the negative i theta in the (*) squeeze operator. The matrix representation of this operator in the orthonormal basis has the square roots of the natural numbers increasing down the diagonal right above the main diagonal. The overcomplete eigenfunctions of this operator are minimum-uncertainty Gaussians that don't disperse over time, and are called coherent states. For 10 points, name this ladder operator symbolized a, which reduces the quantum number of the harmonic oscillator by one.
Using the Pontecorvo relations, a QFT analog for the "flavor" form of this operator sets it equal to a sinusoid of the mixing angle.  
annihilation operator [or the lowering operator; or a until it is read; do NOT accept or prompt on "a-dagger"]