Search for the Z(4430)− at BABAR

Abstract

We report the results of a search for Z ( 4430 ) − decay to J / ψ π − or ψ ( 2 S ) π − in B − , 0 → J / ψ π − K 0 , + and B − , 0 → ψ ( 2 S ) π − K 0 , + decays. The data were collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e + e − collider operating at center-of-mass energy 10.58 GeV, and the sample corresponds to an integrated luminosity of 413 fb − 1 . Each K π − mass distribution exhibits clear K ∗ ( 892 ) and K ∗ 2 ( 1430 ) signals, and the efficiency-corrected spectrum is well described by a superposition of the associated Breit-Wigner intensity distributions, together with an S -wave contribution obtained from the LASS I = 1 / 2 K π − scattering amplitude measurements. Each K π − angular distribution varies significantly in structure with K π − mass, and is represented in terms of low-order Legendre polynomial moments. We find that each J / ψ π − or ψ ( 2 S ) π − mass distribution is well described by the reflection of the measured K π − mass and angular distribution structures. We see no significant evidence for a Z ( 4430 ) − signal for any of the processes investigated, neither in the total J / ψ π − or ψ ( 2 S ) π − mass distribution, nor in the corresponding distributions for the regions of K π − mass for which observation of the Z ( 4430 ) − signal was reported. We obtain branching-fraction upper limits B ( B − → Z − ¯¯¯¯ K 0 , Z − → J / ψ π − ) < 1.5 × 10 − 5 , B ( B 0 → Z − K + , Z − → J / ψ π − ) < 0.4 × 10 − 5 , B ( B − → Z − ¯¯¯¯ K 0 , Z − → ψ ( 2 S ) π − ) < 4.7 × 10 − 5 , and B ( B 0 → Z − K + , Z − → ψ ( 2 S ) π − ) < 3.1 × 10 − 5 at 95% confidence level, where the Z ( 4430 ) − mass and width have been fixed to the reported central values.