Motivated by the recent anomalies related to $b\to (c,u)l{\overline{\nu }}_l$ decays, we perform a theoretical investigation to search for new physics in ${\mathrm{\Lambda }}_b$ decays through $W^{\prime }$ and scalar LQ model. We have studied ${\mathrm{\Lambda }}_b\to ({\mathrm{\Lambda }}_c,p)\tau {\overline{\nu }}_{\tau }$ decays, which involve a $b\to (c,u)\tau {\overline{\nu }}_{\tau }$ quark level transition. To fix the values of the new coupling parameters, we performed ${\chi }^2$ fitting using experimental results of $R_{D^{*}}$, $R_{J/\psi }$, $R_{\pi }^l$, $Br(B_c^{+}\to {\tau }^{+}{\nu }_{\tau })$, $Br(B^{-}\to {\tau }^{-}{\overline{\nu }}_{\tau })$, and $Br(B^0\to {\pi }^{+}{\tau }^{-}\overline{\nu })$. Incorporating the best fit values of new coupling parameters, we have calculated values of the branching ratios, the lepton flavor nonuniversalities ratios, the lepton longitudinal polarization asymmetry, the lepton hadron polarization asymmetry, the forward backward asymmetry, and the ratio of the partially integrated decay rate of ${\mathrm{\Lambda }}_b\to p\tau {\overline{\nu }}_{\tau }$ over the ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c\tau {\overline{\nu }}_{\tau }$. Except for forward-backward asymmetry and leptonic hadron polarization asymmetry, some observables show significant deviations, while others show slight inconsistencies with their standard model predicted values.

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• Hypothetical particle physics models
• Particle decays
• Phenomenology