From the docs:
"Normalizes the input to have 0-mean and/or unit (1) variance across the batch.
This layer computes Batch Normalization as described in .
 S. Ioffe and C. Szegedy, "Batch Normalization: Accelerating Deep Network Training by Reducing Internal Covariate Shift." arXiv preprint arXiv:1502.03167 (2015)."