CMS-PAS-BPH-19-001

CMS-PAS-BPH-19-001
Relative cross sections of the ${\rm B_c^+(2S)}$ and ${\rm B_c^{*+}(2S)}$ states with respect to the ${\rm B_c^+}$ state in proton-proton collisions at $\sqrt{s} =$ 13 TeV
CMS Collaboration
May 2020

Abstract: The ${\rm B_c^+(2S)}$ to ${\rm B_c^+}$ and ${\rm B_c^{+}(2S)}$ to ${\rm B_c^+}$ cross section ratios, as well as the ${\rm B_c^{+}(2S)}$ to ${\rm B_c^+(2S)}$ cross section ratio, are measured in proton-proton collisions at $\sqrt{s} =$ 13 TeV, using a data sample collected by the CMS experiment, corresponding to an integrated luminosity of 143 fb $^{-1}$ . The three measurements are made in the ${\rm B_c^+}$ phase space window defined by transverse momentum $p_{\rm T} >$ 15 GeV and absolute rapidity $\|y\| <$ 2.4, with the excited ${\rm B_c^{()+}(2S)}$ states reconstructed in their ${\rm B_c^+} \pi^+ \pi^-$ decay. The ${\rm B_c^+(2S)}$ to ${\rm B_c^+}$ , ${\rm B_c^{+}(2S)}$ to ${\rm B_c^+}$ , and ${\rm B_c^{+}(2S)}$ to ${\rm B_c^+(2S)}$ cross section ratios, including the (unknown) ${\rm B_c^{()+}(2S) \to B_c^+}\pi^+\pi^-$ branching fractions, are (3.57 $\pm$ 0.69 (stat) $\pm$ 0.32 (syst) )%, (4.91 $\pm$ 0.69 (stat) $\pm$ 0.57 (syst) )%, and 1.39 $\pm$ 0.35 (stat) $\pm$ 0.09 (syst), respectively, where the first uncertainty is statistical and the second is systematic. None of these ratios shows a significant dependence on the $p_{\rm T}$ or $\|y\|$ of the ${\rm B_c^+}$ . The shape of the invariant mass distribution of the dipions emitted in the ${\rm B_c^{(*)+}(2S) \to B_c^+}\pi^+\pi^-$ decays is also reported.
Links: CDS record (PDF) ; inSPIRE record ; HepData record ; CADI line (restricted) ; These preliminary results are superseded in this paper, PRD 102 (2020) 092007. The superseded preliminary plots can be found here.

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