Measurement of the Dipion Mass Spectrum inX(3872)→J/ψπ+π−Decays

Abstract

We measure the dipion mass spectrum in X(3872)--> J/psipi(+) pi(-) decays using 360 pb(-1) of pp collisions at square root s= 1.96 TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity ((3)S(1), (1)P(1), and (3)D(J)) charmonia decaying to J/psipi(+) pi(-), as well as even C-parity states in which the pions are from rho(0) decay. The latter case also encompasses exotic interpretations, such as a D(0)D(*0) molecule. Only the (3)S(1) and J/psirho hypotheses are compatible with our data. Since (3)S(1) is untenable on other grounds, decay via J/psirho is favored, which implies C= +1 for the X(3872). Models for J/psi - rho different angular momenta L are considered. Flexibility in the models, especially the introduction of rho - omega interference, enables good descriptions of our data for both L = 0 and 1.

Measurement of the X(3872) production cross section via decays to J/ψπ + π − in pp collisions at $ \sqrt{s}=7 $ TeV

“…The data are compared to X(3872) signal simulations with and without an intermediate ρ 0 in the J/ψπ + π − decay (generation details are described in section 3). The assumption of an intermediate ρ 0 decay gives better agreement with the data, confirming previous measurements [7,20].…”

“…Events with B-hadron decays are simulated and used in the X(3872) nonprompt-fraction measurement. The X(3872) → J/ψπ + π − decay is generated with an intermediate ρ 0 resonance, as suggested by previous measurements [7,20] and confirmed in this analysis (section 7). In evtgen a two-body phase-space decay is used for the X(3872) → J/ψρ 0 decay, and the ρ 0 decay to a pair of pions is generated with decay-angle distributions reflecting their respective spins.…”

“…The free parameters in the fit are the signal and background yields, the mass and widths of JHEP04 (2013) Figure 2. The J/ψπ + π − invariant-mass distribution in the X(3872) region for two bins of transverse momentum, 10-13.5 GeV (left) and [18][19][20][21][22][23][24][25][26][27][28][29][30]. The lines represent the signal-plus-background fits (solid) and the background-only components (dashed).…”

Measurement of CP Parameters in B- --> D(pi+pi-pi0)K- and Study of the X(3872) in B --> J/psi pi+ pi- K with the BaBar Detector

“…A more detailed study of the dipion mass spectrum has been carried out by CDF II using 360 pb −1 [31]. Fig.…”

A Study of B→c$\bar{c}$γK in the BaBar Experiment

“…CDF [38] and Belle [39] analysed the dipion mass distribution from X(3872) → J/ψ π + π − decays and found them to favour a "ρ-like" shape, suggesting X(3872) → J/ψ ρ 0 . Belle also found evidence for the decay X(3872) → π + π − π 0 in B decays, where the X(3872) decay is thought to proceed via X(3872) → J/ψ ω [36].…”