Study of the $$ {\mathrm{B}}^{+}\to \mathrm{J}/\uppsi \overline{\Lambda}\mathrm{p} $$ decay in proton-proton collisions at $$ \sqrt{s} $$ = 8 TeV

Abstract

AbstractA study of the$$ {\mathrm{B}}^{+}\to \mathrm{J}/\uppsi \overline{\Lambda}\mathrm{p} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>B</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:mover><mml:mi>Λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>p</mml:mi></mml:math>decay using proton-proton collision data collected at$$ \sqrt{s} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt></mml:math>= 8 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.6 fb−1, is presented. The ratio of branching fractions$$ \mathcal{B}\left({\mathrm{B}}^{+}\to \mathrm{J}/\uppsi \overline{\Lambda}\mathrm{p}\right)/\mathcal{B}\left({\mathrm{B}}^{+}\to \mathrm{J}/{\uppsi \mathrm{K}}^{\ast }{(892)}^{+}\right) $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>B</mml:mi><mml:mfenced><mml:mrow><mml:msup><mml:mi>B</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:mover><mml:mi>Λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>p</mml:mi></mml:mrow></mml:mfenced><mml:mo>/</mml:mo><mml:mi>B</mml:mi><mml:mfenced><mml:mrow><mml:msup><mml:mi>B</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:msup><mml:mi>ψK</mml:mi><mml:mo>∗</mml:mo></mml:msup><mml:msup><mml:mfenced><mml:mn>892</mml:mn></mml:mfenced><mml:mo>+</mml:mo></mml:msup></mml:mrow></mml:mfenced></mml:math>is measured to be (1.054±0.057(stat)±0.035(syst)±0.011($$ \mathcal{B} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>B</mml:mi></mml:math>))%, where the last uncertainty reflects the uncertainties in the world-average branching fractions of$$ \overline{\Lambda} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mi>Λ</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>and K*(892)+decays to reconstructed final states. The invariant mass distributions of the$$ \mathrm{J}/\uppsi \overline{\Lambda} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:mover><mml:mi>Λ</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>, J/ψp, and$$ \overline{\Lambda}\mathrm{p} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mi>Λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>p</mml:mi></mml:math>systems produced in the$$ {\mathrm{B}}^{+}\to \mathrm{J}/\uppsi \overline{\varLambda}\mathrm{p} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>B</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:mover><mml:mi>Λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>p</mml:mi></mml:math>decay are investigated and found to be inconsistent with the pure phase space hypothesis. The analysis is extended by using a model-independent angular amplitude analysis, which shows that the observed invariant mass distributions are consistent with the contributions from excited kaons decaying to the$$ \overline{\Lambda}\mathrm{p} $$<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mi>Λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>p</mml:mi></mml:math>system.