  High-frequency quasiperiodic oscillations of the X-ray flux comming from
black-hole binaries have the potential to provide precise estimates of the mass
and the spin of the central black hole, if an adequate model for them was
available. There are several models in the literature but none of them is
commonly accepted. One way to test the available models is to confront their
predictions for the masses of black holes with results obtained through other
methods. Here, we study the mass bounds that nine of the most commonly used
models provide for the three microquasars with known masses GRS 1915+105, GRO
1655-40 and XTE 1550-564 which display high-frequency quasiperiodic
oscillations in their X-ray spectra. We also propose a statistical method for
the assessment of the average success of the models. The results allow us to
discard five of them. Here, "the mass problem" designates the conflict between
their predictions and the reference masses.

High Energy Astrophysical Phenomena