Observation of Two Excited B-c(+) States and Measurement of the B-c(+) (2S) Mass in pp Collisions at root s=13 TeV

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Abstract

Signals consistent with the B-c(+)(2S) and B-c*(+)(2S) states are observed in proton-proton collisions at root s = 13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb(-1), collected by the CMS experiment during the 2015-2018 LHC running periods. These excited (b) over barc states are observed in the B-c(+)pi(+)pi(-) invariant mass spectrum, with the ground state B-c(+) reconstructed through its decay to J/psi pi(+). The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1 +/- 1.5(stat) +/- 0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the B-c(+)(2S) meson is measured to be 6871.0 +/- 1.2(stat) +/- 0.8(syst) +/- 0.8(B-c(+)) MeV, where the last term corresponds to the uncertainty in the world-average B-c(+) mass.
Original languageEnglish
Article number132001
JournalPhysical Review Letters
Volume122
Issue number13
Number of pages17
ISSN0031-9007
DOIs
Publication statusPublished - 2 Apr 2019
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 114 Physical sciences
  • B-C SPECTROSCOPY
  • MESONS

Cite this

@article{c713ff8302584cd29ea34bb54c883cc2,
title = "Observation of Two Excited B-c(+) States and Measurement of the B-c(+) (2S) Mass in pp Collisions at root s=13 TeV",
abstract = "Signals consistent with the B-c(+)(2S) and B-c*(+)(2S) states are observed in proton-proton collisions at root s = 13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb(-1), collected by the CMS experiment during the 2015-2018 LHC running periods. These excited (b) over barc states are observed in the B-c(+)pi(+)pi(-) invariant mass spectrum, with the ground state B-c(+) reconstructed through its decay to J/psi pi(+). The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1 +/- 1.5(stat) +/- 0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the B-c(+)(2S) meson is measured to be 6871.0 +/- 1.2(stat) +/- 0.8(syst) +/- 0.8(B-c(+)) MeV, where the last term corresponds to the uncertainty in the world-average B-c(+) mass.",
keywords = "114 Physical sciences, B-C SPECTROSCOPY, MESONS",
author = "{The CMS Collaboration} and Sirunyan, {A. M.} and P. Eerola and H. Kirschenmann and J. Pekkanen and M. Voutilainen and J. Havukainen and Heikkil{\"a}, {J. K.} and T. J{\"a}rvinen and V. Karim{\"a}ki and R. Kinnunen and T. Lamp{\'e}n and K. Lassila-Perini and S. Laurila and S. Lehti and T. Lind{\'e}n and P. Luukka and T. M{\"a}enp{\"a}{\"a} and H. Siikonen and E. Tuominen and J. Tuominiemi and T. Tuuva",
year = "2019",
month = "4",
day = "2",
doi = "10.1103/PhysRevLett.122.132001",
language = "English",
volume = "122",
journal = "Physical Review Letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "13",

}

TY - JOUR

T1 - Observation of Two Excited B-c(+) States and Measurement of the B-c(+) (2S) Mass in pp Collisions at root s=13 TeV

AU - The CMS Collaboration

AU - Sirunyan, A. M.

AU - Eerola, P.

AU - Kirschenmann, H.

AU - Pekkanen, J.

AU - Voutilainen, M.

AU - Havukainen, J.

AU - Heikkilä, J. K.

AU - Järvinen, T.

AU - Karimäki, V.

AU - Kinnunen, R.

AU - Lampén, T.

AU - Lassila-Perini, K.

AU - Laurila, S.

AU - Lehti, S.

AU - Lindén, T.

AU - Luukka, P.

AU - Mäenpää, T.

AU - Siikonen, H.

AU - Tuominen, E.

AU - Tuominiemi, J.

AU - Tuuva, T.

PY - 2019/4/2

Y1 - 2019/4/2

N2 - Signals consistent with the B-c(+)(2S) and B-c*(+)(2S) states are observed in proton-proton collisions at root s = 13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb(-1), collected by the CMS experiment during the 2015-2018 LHC running periods. These excited (b) over barc states are observed in the B-c(+)pi(+)pi(-) invariant mass spectrum, with the ground state B-c(+) reconstructed through its decay to J/psi pi(+). The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1 +/- 1.5(stat) +/- 0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the B-c(+)(2S) meson is measured to be 6871.0 +/- 1.2(stat) +/- 0.8(syst) +/- 0.8(B-c(+)) MeV, where the last term corresponds to the uncertainty in the world-average B-c(+) mass.

AB - Signals consistent with the B-c(+)(2S) and B-c*(+)(2S) states are observed in proton-proton collisions at root s = 13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb(-1), collected by the CMS experiment during the 2015-2018 LHC running periods. These excited (b) over barc states are observed in the B-c(+)pi(+)pi(-) invariant mass spectrum, with the ground state B-c(+) reconstructed through its decay to J/psi pi(+). The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1 +/- 1.5(stat) +/- 0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the B-c(+)(2S) meson is measured to be 6871.0 +/- 1.2(stat) +/- 0.8(syst) +/- 0.8(B-c(+)) MeV, where the last term corresponds to the uncertainty in the world-average B-c(+) mass.

KW - 114 Physical sciences

KW - B-C SPECTROSCOPY

KW - MESONS

U2 - 10.1103/PhysRevLett.122.132001

DO - 10.1103/PhysRevLett.122.132001

M3 - Article

VL - 122

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 13

M1 - 132001

ER -