The relation between white dwarf mass and orbital period for binary millisecond radio pulsars orbital period 1<=P-orb<=20 days

We present a white dwarf mass versus orbital period relation for binary millisecond pulsars (MSP) with short orbital period (less than 20 days) based on detailed binary evolution calculations in which orbital angular momentum losses are included. It is shown that for binary millisecond pulsars with orbital periods in this range, the relation between white dwarf mass and orbital period is more complex than relations based on ''conservative'' binary evolution so far used in literature. Due to effects of angular momentum losses the orbital periods increase by a smaller factor during the evolution; leading to systematically larger white dwarf masses at the same final binary period. At the shortest orbital periods (around one day) the difference may be as large as 25 percent. For orbital period longer than 20 days the difference becomes negligible.