Measurement of B-c(2S)(+) and B-c*(2S)(+) cross section ratios in proton-proton collisions at root s=13 TeV

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.

Description
Keywords
Astronomy & Astrophysics, Physics, Particles & Fields, Physics
Citation
Sirunyan, A. M., Tumasyan, A., Adam, W., Ambrogi, F., Bergauer, T., Dragicevic, M., Erö, J., Escalante Del Valle, A., Frühwirth, R., Jeitler, M., Krammer, N., Lechner, L., Liko, D., Madlener, T., Mikulec, I., Pitters, F. M., Rad, N., Schieck, J., … Schöfbeck, R. (2020). Measurement of Bc(2S)+ and Bc*(2S)+ cross section ratios in proton-proton collisions at s=13  TeV. In Physical Review D (Vol. 102, Issue 9). American Physical Society (APS). https://doi.org/10.1103/physrevd.102.092007