def METHOD_NAME(self, pars):
    """
    Returns:
        modification tensor: Shape (n_modifiers, n_global_samples, n_alphas, n_global_bin)
    """
    tensorlib, _ = get_backend()
    if not self.param_viewer.index_selection:
        return
    tensorlib, _ = get_backend()
    if self.batch_size is None:
        flat_pars = pars
    else:
        flat_pars = tensorlib.reshape(pars, (-1,))
    shapefactors = tensorlib.gather(flat_pars, self.access_field)
    results_shapesys = tensorlib.einsum(
        'mab,s->msab', shapefactors, self.sample_ones
    )
    results_shapesys = tensorlib.where(
        self.shapesys_mask, results_shapesys, self.shapesys_default
    )
    return results_shapesys