Journal Article

Measurement of the$$ {\\Lambda}_b^0 $$→ J/ψΛ angular distribution and the$$ {\\Lambda}_b^0 $$polarisation in pp collisions,Measurement of the$$ {\\Lambda}_b^0 $$ → J/ψΛ angular distribution and the$$ {\\Lambda}_b^0 $$polarisation in pp collisions

Vorobyev, V., Chefdeville, M., Di Canto, A., Alexander, M., Jones, C. R., Durante, P., Gao, Y., Eschle, J., Brossa Gonzalo, A., Yang, Z., Cardinale, R., Meinert, N., Mead, J. V., Barlow, R. J., Schmelling, M., Vázquez Sierra, C., Cai, H., Bedeschi, F., Swientek, K., Stefko, P., Millard, E., Pugatch, V., Ketel, T., Bobulska, D., Ferro-Luzzi, M., Lefèvre, R., Zhang, S., Golubkov, D., Dalseno, J., Jawahery, A., Lai, A., Schneider, O., Rama, M., Bozzi, C., Carniti, P., Tran, M. T., Fontana, M., Straticiuc, M., Cenci, R., Ene, A., Smith, E., Zhou, X., Gibson, V., Mulder, M., Ramos Pernas, M., Jiang, F., Bezshyiko, Ia, Bertella, C., Tuning, N., Cobbledick, J. L., Kvaratskheliya, T., Morris, A. B., Williams, T., Carboni, G., Didenko, S., Calero Diaz, L., McNulty, R., Baldini, W., Ponce, S., Karacson, M., Nguyen-Mau, C., Pomery, G. J., Decamp, D., Hancock, T. H., Brea Rodriguez, A., Skidmore, N., Chulikov, V., Romanovskiy, V., Malecki, B., Cadeddu, S., Pappagallo, M., Kecke, M., Nanut, T., Marino, P., Materok, M., Merli, A., Epple, E., Dey, B., Lu, Y., Wiedner, D., Yu, J., Byczynski, W., Zarebski, K. A., Hatch, M., Maccolini, S., Mogini, A., Coelho, J. A. B., Yin,

2020

Overview

This paper presents an analysis of the$$ {\\Lambda}_b^0 $$Λ b 0 → J/ψ Λ angular distribution and the transverse production polarisation of$$ {\\Lambda}_b^0 $$Λ b 0 baryons in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb − 1 , collected with the LHCb experiment. The polarisation is determined in a fiducial region of$$ {\\Lambda}_b^0 $$Λ b 0 transverse momentum and pseudorapidity of 1 < p T < 20 GeV/ c and 2 < η < 5, respectively. The data are consistent with$$ {\\Lambda}_b^0 $$Λ b 0 baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ → pπ − decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration.