Test of lepton universality with Λb0→pK−ℓ+ℓ− decays

• Published in: The journal of high energy physics 2020-05, Vol.2020 (5)
• Main Authors: Alexander, M., Alves, A. A., Baryshnikov, F., Blusk, S., Boldyrev, A., Bondar, A., Bondar, N., Borsato, M., Butter, J. S., Camargo Magalhaes, P., Coco, V., Cojocariu, L., De Aguiar Francisco, O., De Serio, M., Demmer, M., Deschamps, O., Dziewiecki, M., Eidelman, S., Eisenhardt, S., Ek-In, S., Escher, S., Fan, J., Fazzini, D., Féo, M., Fini, R. A., Fu, J., Galli, D., Gallorini, S., Gandelman, M., Garcia Plana, B., Göbel, C., Golutvin, A., Govorkova, E., Graciani Diaz, R., Graugés, E., Graziani, G., Guz, Yu, Günther, P. A., Hasse, C., Hu, J., Hynds, D., Ibis, P., Jacobsson, R., Johnson, D., Jurik, N., Kariuki, J. M., Kazeev, N., Kecke, M., Kenzie, M., Klimaszewski, K., Krokovny, P., Leflat, A., Liu, G., Lopes, J. H., Lucchesi, D., Machefert, F., Malinin, A., Manera Escalero, R., Marino, P., Mathad, A., Mathe, Z., Mineev, O., Mödden, A., Mogini, A., Müller, D., Neri, N., Nguyen, T. D., Pais, P. R., Pastore, A., Pepe Altarelli, M., Popov, A., Raven, G., Reiss, F., Remon Alepuz, C., Richards, S., Rollings, A., Saborido Silva, J. J., Sagidova, N., Sergi, A., Shapkin, M., Skwarnicki, T., Spadaro Norella, E., Sun, J., Sun, Y., Tisserand, V., Tran, M. T., Ustyuzhanin, A., Uwer, U., van Beuzekom, M., Veronesi, M., Vitkovskiy, A., Vorobyev, V., Voropaev, N., Waldi, R., Wang, J., Westhenry, B. D. C., Whitehead, M., Wilson, F. F., Wotton, S. A., Yang, Z.
• Format: Article
• Language: English
• Subjects: Classical and Quantum Gravitation; Decay; Elementary Particles; High energy physics; Large Hadron Collider; Leptons; Luminosity; Particle collisions; Physics; Physics and Astronomy; Protons; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Experimental Physics; Relativity Theory; String Theory
• ISSN: 1029-8479
• DOI: 10.1007/JHEP05(2020)040

A bstract The ratio of branching fractions of the decays Λ b 0 → pK − e + e − and Λ b 0 → pK − μ + μ − , R pK − 1 , is measured for the first time using proton-proton collision data corresponding to an integrated luminosity of 4 . 7 fb − 1 recorded with the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV. In the dilepton mass-squared range 0 . 1 < q 2 < 6 . 0 GeV 2 /c 4 and the pK − mass range m ( pK − ) < 2600 MeV /c 2 , the ratio of branching fractions is measured to be R pK − 1 = 1.17 − 0.16 + 0.18 ± 0.07 , where the first uncertainty is statistical and the second systematic. This is the first test of lepton universality with b baryons and the first observation of the decay Λ b 0 → pK − e + e − .