Two identical bar magnets of magnetic moment M each, are placed along X and Y- axes, respectively  at a distance d from the origin (as shown in the figure). The origin lies on perpendicular bisector of magnet placed on X – axis and on the magnetic axis of magnet placed on Y – asix. If the magnigtude of total magnetic field at the orgin is $B=\alpha \left[\frac{{\mu }_0}{4\pi }\frac{M}{d^3}\right]$  then the value of constant   will be (d > > l, where l is the length of the bas magnets and direction of N to S in magnets is opposite with respect to each other)