The observation possibility of $B_c$ excitations at LHC

Abstract

It is shown that in the decays $B_c(2P)\to B_c^* \gamma^\mathrm{hard}$, $B_c(3P)\to B_c^* \gamma^\mathrm{hard}$ and $B_c(2S)\to B_c^* +\pi^+\pi^-$ followed by the decay $B_c^*\to B_c +\gamma^\mathrm{soft}$ the loss of the soft photon $\gamma^\mathrm{soft}$ do not wash out peaks from the initial excitations. The relative yields of $B_c^*$, 2P-wave, and 3P-wave states of $B_c$ meson at LHC are estimated as function of transverse energy of emitted photon $\gamma^\mathrm{hard}$. It is pointed out, that the decays $B_c(2S) \to B_c(B_c^*)+\pi^+\pi^-$ could provide a new information about a $\sigma$ resonance nature.