We studied the average orbital modulation of various parameters ( \gamma -ray flux , H \alpha emission line , optical V band brightness ) of the radio- and \gamma -ray emitting Be/X-ray binary LS I +61 ^ { \circ } 303 .
Using the Spearman rank correlation test , we found highly significant correlations between the orbital variability of the equivalent width of the blue hump of the H \alpha and Fermi -LAT flux with a Spearman p-value \sim 2 \times 10 ^ { -5 } , and the equivalent widths ratio EW _ { B } / EW _ { R } and Fermi -LAT flux with p-value \sim 9 \times 10 ^ { -5 } .
We also found a significant anti-correlation between Fermi -LAT flux and V band magnitude with p-value \sim 7 \times 10 ^ { -4 } . All these correlations refer to the average orbital variability , and we conclude that the H \alpha and \gamma -ray emission processes in LS I +61 ^ { \circ } 303 are connected .
The possible physical scenario is briefly discussed .