# Evidence for exotic hadron contributions to $\Lambda_b^0 \to J/\psi p \pi^-$ decays

Abstract : A full amplitude analysis of $\Lambda_b^0 \to J/\psi p \pi^-$ decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$. A significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations $N\to p\pi^-$, either the $P_c(4380)^+$ and $P_c(4450)^+\to J/\psi p$ states, previously observed in $\Lambda_b^0 \to J/\psi p K^-$ decays, or the $Z_c(4200)^-\to J/\psi \pi^-$ state, previously reported in $B^0 \to J/\psi K^+ \pi^-$ decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the $P_c(4380)^+$ and $P_c(4450)^+$ production rates expected from their previous observation taking account of Cabibbo suppression.
Type de document :
Article dans une revue
Physical Review Letters, American Physical Society, 2016, 117, pp.082003 〈10.1103/PhysRevLett.117.082003〉

http://hal.in2p3.fr/in2p3-01336333
Contributeur : Danielle Cristofol <>
Soumis le : jeudi 23 juin 2016 - 08:20:09
Dernière modification le : mardi 13 novembre 2018 - 21:58:08

### Citation

R. Aaij, C. Abellán Beteta, B. Adeva, M. Adinolfi, Z. Ajaltouni, et al.. Evidence for exotic hadron contributions to $\Lambda_b^0 \to J/\psi p \pi^-$ decays. Physical Review Letters, American Physical Society, 2016, 117, pp.082003 〈10.1103/PhysRevLett.117.082003〉. 〈in2p3-01336333〉

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