Measurement of the Dipion Mass Spectrum in X(3872) → J/ψπ⁺π^- Decays

Authors

A. Abulencia, University of Illinois, Urbana
Kenneth A. Bloom, University of Nebraska-LincolnFollow
CDF Collaboration

Document Type

Article

Date of this Version

3-17-2006

Comments

Published by American Physical Society. Phys. Rev. Lett. 96, 102002 (2006). http://prl.aps.org. Copyright © 2006 American Physical Society. Permission to use.

Abstract

We measure the dipion mass spectrum in X(3872) → J/ψ π ⁺ π ^- decays using 360 pb^-1 of p̅p collisions at √s = 1.96 TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity (³S₁, ¹P₁, and ³D_J) charmonia decaying to J/ π ⁺ π ^-, as well as even C-parity states in which the pions are from ρ⁰ decay. The latter case also encompasses exotic interpretations, such as a D⁰D̅^*0 molecule. Only the ³S₁ and J/ψρ hypotheses are compatible with our data. Since ³S₁ is untenable on other grounds, decay via J/ψρ is favored, which implies C= +1 for the X(3872). Models for different J/ψ-ρ angular momenta L are considered. Flexibility in the models, especially the introduction of ρ- ω interference, enables good descriptions of our data for both L = 0 and 1.