2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/45210The Fermi motion parameter $p_{_F}$ is the most important parameter of ACCMM model, and the value $p_{_F} \sim 0.3$ GeV has been used without clear theoretical or experimental evidence. So, we attempted to extract the possible value for $p_{_F}$ theoretically in the relativistic quark model using quantum mechanical variational method. We obtained $p_{_F} \sim 0.5$ GeV, which is somewhat larger than 0.3, and we also derived the eigenvalue of $E_B \simeq 5.5$ GeV, which is is reasonable agreement with $m_B=5.28$ GeV.11 pages (no figures)High Energy Physics - Phenomenologytext