Observation of New Resonances Decaying to J / ψ K + and J / ψ ϕ

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The first observation of exotic states with a new quark content c¯cu¯s decaying to the J/ψK+ final state is reported with high significance from an amplitude analysis of the B+→J/ψϕK+ decay. The analysis is carried out using proton-proton collision data corresponding to a total integrated luminosity of 9  fb−1 collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. The most significant state, Zcs(4000)+, has a mass of 4003±6+4−14  MeV, a width of 131±15±26  MeV, and spin parity JP=1+, where the quoted uncertainties are statistical and systematic, respectively. A new 1+  X(4685) state decaying to the J/ψϕ final state is also observed with high significance. In addition, the four previously reported J/ψϕ states are confirmed and two more exotic states, Zcs(4220)+ and X(4630), are observed with significance exceeding 5 standard deviations.

Originele taal-2English
Aantal pagina's11
TijdschriftPhysical Review Letters
Nummer van het tijdschrift8
StatusPublished - 17-aug-2021

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