Semileptonic decays of heavy baryons in the relativistic quark model

Semileptonic decays of heavy baryons consisting of one heavy ($Q=b$, $c$) and two light ($q=u$, $d$, $s$) quarks are considered in the heavy-quark-light-diquark approximation. The relativistic quasipotential equation is used for obtaining masses and wave functions of both diquarks and baryons within the constituent quark model. The weak transition matrix elements are expressed through the overlap integrals of the baryon wave functions. The Isgur-Wise functions are determined in the whole accessible kinematic range. The exclusive semileptonic decay rates and different asymmetries are calculated with applying the heavy quark $1/m_Q$ expansion. The evaluated ${\Lambda }_b\to {\Lambda }_{c}l\nu$ decay rate agrees with its experimental value.