Measurement of B-c(2S)(+) and B-c*(2S)(+) cross section ratios in proton-proton collisions at root s=13 TeV
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Abstract
The ratios of the ({B}{c}{\left(2S\right)}^{+}) to ({B}{c}^{+}), ({B}{c}^{*}{\left(2S\right)}^{+}) to ({B}{c}^{+}), and ({B}{c}^{*}{\left(2S\right)}^{+}) to ({B}{c}{\left(2S\right)}^{+}) production cross sections are measured in proton-proton collisions at (\sqrt{s}=13\text{}\text{}\mathrm{TeV}), using a data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of (143\text{}\text{}{\mathrm{fb}}^{-1}). The three measurements are made in the ({B}{c}^{+}) meson phase space region defined by the transverse momentum ({p}{T}>15\text{}\text{}\mathrm{GeV}) and absolute rapidity (|y|<2.4), with the excited ({B}{c}^{\left(*\right)}{\left(2S\right)}^{+}) states reconstructed through the ({B}{c}^{\left(\right)+}{\pi }^{+}{\pi }^{-}), followed by the ({B}{c}^{+}\to J/\psi {\pi }^{+}) and (J/\psi \to {\mu }^{+}{\mu }^{-}) decays. The ({B}{c}{\left(2S\right)}^{+}) to ({B}{c}^{+}), ({B}{c}^{}{\left(2S\right)}^{+}) to ({B}{c}^{+}), and ({B}{c}^{}{\left(2S\right)}^{+}) to ({B}{c}{\left(2S\right)}^{+}) cross section ratios, including the unknown ({B}{c}^{\left(\right)}{\left(2S\right)}^{+}\to {B}{c}^{\left(*\right)+}{\pi }^{+}{\pi }^{-}) branching fractions, are (\left(3.47±0.63\left(\mathrm{stat}\right)±0.33\left(\mathrm{syst}\right)\right)%), (\left(4.69±0.71\left(\mathrm{stat}\right)±0.56\left(\mathrm{syst}\right)\right)%), and (1.35±0.32\left(\mathrm{stat}\right)±\phantom{\rule{0ex}{0ex}}0.09\left(\mathrm{syst}\right)), respectively. None of these ratios shows a significant dependence on the ({p}{T}) or (|y|) of the ({B}{c}^{+}) meson. The normalized dipion invariant mass distributions from the decays ({B}{c}^{\left(\right)}{\left(2S\right)}^{+}\to {B}_{c}^{\left(\right)+}{\pi }^{+}{\pi }^{-}) are also reported.