Direct measurements of the branching fractions for D 0 → K − e + ν e and D 0 → π − e + ν e and determinations of the form factors f + K ( 0 ) and f + π ( 0 )

Direct measurements of the branching fractions for D 0 → K − e + ν e and D 0 → π − e + ν e and determinations of the form factors f + K ( 0 ) and f + π ( 0 )