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arXiv · 1709.04247

$χ_{c1}$ and $χ_{c2}$ resonance parameters with the decays $χ_{c1,c2}\to J/ψμ^+μ^-$

LHCb collaboration·R. Aaij·B. Adeva·M. Adinolfi·Z. Ajaltouni·S. Akar·J. Albrecht·F. Alessio·M. Alexander·A. Alfonso Albero·S. Ali·G. Alkhazov·P. Alvarez Cartelle·A. A. Alves Jr·S. Amato·S. Amerio·Y. Amhis·L. An·L. Anderlini·G. Andreassi·M. Andreotti·J. E. Andrews·R. B. Appleby·F. Archilli·P. d'Argent·J. Arnau Romeu·A. Artamonov·M. Artuso·E. Aslanides·M. Atzeni·G. Auriemma·M. Baalouch·I. Babuschkin·S. Bachmann·J. J. Back·A. Badalov·C. Baesso·S. Baker·V. Balagura·W. Baldini·A. Baranov·R. J. Barlow·C. Barschel·S. Barsuk·W. Barter·F. Baryshnikov·V. Batozskaya·V. Battista·A. Bay·L. Beaucourt·J. Beddow·F. Bedeschi·I. Bediaga·A. Beiter·L. J. Bel·N. Beliy·V. Bellee·N. Belloli·K. Belous·I. Belyaev·E. Ben-Haim·G. Bencivenni·S. Benson·S. Beranek·A. Berezhnoy·R. Bernet·D. Berninghoff·E. Bertholet·A. Bertolin·C. Betancourt·F. Betti·M. -O. Bettler·M. van Beuzekom·Ia. Bezshyiko·S. Bifani·P. Billoir·A. Birnkraut·A. Bizzeti·M. Bjørn·T. Blake·F. Blanc·S. Blusk·V. Bocci·T. Boettcher·A. Bondar·N. Bondar·I. Bordyuzhin·S. Borghi·M. Borisyak·M. Borsato·F. Bossu·M. Boubdir·T. J. V. Bowcock·E. Bowen·C. Bozzi·S. Braun·T. Britton·J. Brodzicka·D. Brundu·E. Buchanan
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Abstract

The decays $χ_{c1} \rightarrow J/ψμ^+ μ^-$ and $χ_{c2} \rightarrow J/ψμ^+ μ^-$ are observed and used to study the resonance parameters of the $χ_{c1}$ and $χ_{c2}$ mesons. The masses of these states are measured to be m(χ_{c1}) = 3510.71 \pm 0.04(stat) \pm 0.09(syst)MeV\,, m(χ_{c2}) = 3556.10 \pm 0.06(stat) \pm 0.11(syst)MeV\,, where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. The momentum-scale uncertainties largely cancel in the mass difference m(χ_{c2}) - m(χ_{c1}) = 45.39 \pm 0.07(stat) \pm 0.03(syst)MeV\,. The natural width of the $χ_{c2}$ meson is measured to be $$Γ(χ_{c2}) = 2.10 \pm 0.20(stat) \pm 0.02(syst)MeV\,.$$ These results are in good agreement with and have comparable precision to the current world averages.

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LHCb collaboration, R. Aaij, B. Adeva, M. Adinolfi, Z. Ajaltouni, S. Akar, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves Jr, S. Amato, S. Amerio, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, J. E. Andrews, R. B. Appleby, F. Archilli, P. d'Argent, J. Arnau Romeu, A. Artamonov, M. Artuso, E. Aslanides, M. Atzeni, G. Auriemma, M. Baalouch, I. Babuschkin, S. Bachmann, J. J. Back, A. Badalov, C. Baesso, S. Baker, V. Balagura, W. Baldini, A. Baranov, R. J. Barlow, C. Barschel, S. Barsuk, W. Barter, F. Baryshnikov, V. Batozskaya, V. Battista, A. Bay, L. Beaucourt, J. Beddow, F. Bedeschi, I. Bediaga, A. Beiter, L. J. Bel, N. Beliy, V. Bellee, N. Belloli, K. Belous, I. Belyaev, E. Ben-Haim, G. Bencivenni, S. Benson, S. Beranek, A. Berezhnoy, R. Bernet, D. Berninghoff, E. Bertholet, A. Bertolin, C. Betancourt, F. Betti, M. -O. Bettler, M. van Beuzekom, Ia. Bezshyiko, S. Bifani, P. Billoir, A. Birnkraut, A. Bizzeti, M. Bjørn, T. Blake, F. Blanc, S. Blusk, V. Bocci, T. Boettcher, A. Bondar, N. Bondar, I. Bordyuzhin, S. Borghi, M. Borisyak, M. Borsato, F. Bossu, M. Boubdir, T. J. V. Bowcock, E. Bowen, C. Bozzi, S. Braun, T. Britton, J. Brodzicka, D. Brundu, E. Buchanan. 2017-12-19. $χ_{c1}$ and $χ_{c2}$ resonance parameters with the decays $χ_{c1,c2}\to J/ψμ^+μ^-$. https://doi.org/10.1103/physrevlett.119.221801

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