The first observation of exotic states with a new quark content $c \bar{c} u \bar{s}$ decaying to the $J/\psi K^+$ final state is reported with high significance from an amplitude analysis of the $B^+ \to J/\psi \phi K^+$ 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 centre-of-mass energies of 7, 8 and 13 TeV. The most significant state, $Z_{cs}(4000)^+$, has a mass of $4003\pm6\,^{+\,\phantom{0}4}_{-\,14}$ MeV, a width of $131\pm15\pm26$ MeV, and spin-parity $J^P=1^+$, where the quoted uncertainties are statistical and systematic, respectively. A new $1^+$ $X(4685)$ state decaying to the $J/\psi \phi$ final sta...
The first observation of exotic states with a new quark content $c\bar{c}u\bar{s}$ decaying to the $...
The first full amplitude analysis of B+\u2192J/\u3c8\u3c6K+ with J/\u3c8\u2192\u3bc+\u3bc-, \u3c6\u2...
The first full amplitude analysis of B+→J/ψϕK+ with J/ψ→μ+μ−, ϕ→K+K− decays is performed with a data...
The first observation of exotic states with a new quark content c¯cu¯s decaying to the J/ψK+ final s...
The first observation of exotic states with a new quark content cc¯us¯ decaying to the J/ψK+ final s...
The first observation of exotic states with a new quark content c anti-c u anti-s decaying to the J/...
The first observation of exotic states with a new quark content cc[over ¯]us[over ¯] decaying to the...
The first observation of exotic states with a new quark content c¯cu¯s decaying to the J/ψK+ final s...
The first observation of exotic states with a new quark content c ¯ c u ¯ s decaying to the...
The first observation of exotic states with a new quark content ccus decaying to the $J/\psi K^{+}$ ...
The first observation of exotic states with a new quark content $c\bar{c}u\bar{s}$ decaying to the $...
The first full amplitude analysis of B+\u2192J/\u3c8\u3c6K+ with J/\u3c8\u2192\u3bc+\u3bc-, \u3c6\u2...
The first full amplitude analysis of B+→J/ψϕK+ with J/ψ→μ+μ−, ϕ→K+K− decays is performed with a data...
The first observation of exotic states with a new quark content c¯cu¯s decaying to the J/ψK+ final s...
The first observation of exotic states with a new quark content cc¯us¯ decaying to the J/ψK+ final s...
The first observation of exotic states with a new quark content c anti-c u anti-s decaying to the J/...
The first observation of exotic states with a new quark content cc[over ¯]us[over ¯] decaying to the...
The first observation of exotic states with a new quark content c¯cu¯s decaying to the J/ψK+ final s...
The first observation of exotic states with a new quark content c ¯ c u ¯ s decaying to the...
The first observation of exotic states with a new quark content ccus decaying to the $J/\psi K^{+}$ ...
The first observation of exotic states with a new quark content $c\bar{c}u\bar{s}$ decaying to the $...
The first full amplitude analysis of B+\u2192J/\u3c8\u3c6K+ with J/\u3c8\u2192\u3bc+\u3bc-, \u3c6\u2...
The first full amplitude analysis of B+→J/ψϕK+ with J/ψ→μ+μ−, ϕ→K+K− decays is performed with a data...