Observation and Properties of the X(3872) Decaying to J/psipi+pi- in pp¯ Collisions at &surd;(s)=1.96 TeV (original) (raw)
2004, Physical Review Letters
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Abstract
We report the observation of the X(3872) in the J/ψπ+π- channel, with J/ψ decaying to μ+μ-, in pp¯ collisions at √(s)=1.96 TeV. Using approximately 230 pb-1 of data collected with the RunII D0 detector, we observe 522±100 X(3872) candidates. The mass difference between the X(3872) state and the J/ψ is measured to be 774.9±3.1(stat)±3.0(syst) MeV/c2. We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the ψ(2S) state.
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The production of the X(3872) is studied in pp collisions at $ \sqrt{s}=7 $ TeV, using decays to J/ψπ + π −, where the J/ψ decays to two muons. The data were recorded by the CMS experiment and correspond to an integrated luminosity of 4.8 fb−1. The measurements are performed in a kinematic range in which the X(3872) candidates have a transverse momentum 10 < p T < 50 GeV and rapidity |y| < 1.2. The ratio of the X(3872) and ψ(2S) cross sections times their branching fractions into J/ψπ + π − is measured as a function of p T. In addition, the fraction of X(3872) originating from B decays is determined. From these measurements the prompt X(3872) differential cross section times branching fraction as a function of p T is extracted. The π + π − mass spectrum of the J/ψπ + π − system in the X(3872) decays is also investigated.
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We present results from a study of X(3872) → ππJ/ψ decays produced via exclusive B → KX(3872) decays. We determine the mass to be M X(3872) = (3871.84±0.27(stat)±0.19 (syst)) MeV, a 90% CL upper limit on the natural width of Γ X(3872) < 1.2 MeV, the product branching fraction B(B + → K + X(3872)) × B(X(3872) → π + π − J/ψ) = (8.61 ± 0.82 (stat) ± 0.52 (syst)) × 10 −6 , and a ratio of branching fractions B(B 0 → K 0 X(3872))/B(B + → K + X(3872)) = 0.50 ± 0.14 (stat) ± 0.04 (syst). The difference in mass between the X(3872) → π + π − J/ψ signals in B + and B 0 decays is ∆M X(3872) = (−0.69 ± 0.97(stat) ± 0.19(syst)) MeV. A search for a charged partner of the X(3872) in the decaysB 0 → K − X + or B + → K 0 X + , X + → π + π 0 J/ψ resulted in upper limits on the product branching fractions for these processes that are well below expectations for the case that the X(3872) is the neutral member of an isospin triplet. In addition, we examine possible J P C quantum number assignments for the X(3872) based on comparisons of angular correlations between final state particles in X(3872) → π + π − J/ψ decays with simulated data for J P C values of 1 ++ and 2 −+. We examine the influence of ρ-ω interference in the M (π + π −) spectrum. The analysis is based on a 711 fb −1 data sample that contains 772 million BB meson pairs collected at the Υ(4S) resonance in the Belle detector at the KEKB e + e − collider.
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We present an analysis of the mass of the Xð3872Þ reconstructed via its decay to J= c þ À using 2: 4 fbÀ1 of integrated luminosity from p" p collisions at ffiffiffi sp ¼ 1: 96 TeV, collected with the CDF II detector at the Fermilab Tevatron. The possible existence of two nearby mass states is investigated. Within the limits of our experimental resolution the data are consistent with a single state, and having no evidence for two states we set upper limits on the mass difference between two hypothetical states for different assumed ratios of contributions to ...
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The production of the X(3872) is studied in pp collisions at √ s = 7 TeV, using decays to J/ψπ + π − , where the J/ψ decays to two muons. The data were recorded by the CMS experiment and correspond to an integrated luminosity of 4.8 fb −1. The measurements are performed in a kinematic range in which the X(3872) candidates have a transverse momentum 10 < p T < 50 GeV and rapidity |y| < 1.2. The ratio of the X(3872) and ψ(2S) cross sections times their branching fractions into J/ψπ + π − is measured as a function of p T. In addition, the fraction of X(3872) originating from B decays is determined. From these measurements the prompt X(3872) differential cross section times branching fraction as a function of p T is extracted. The π + π − mass spectrum of the J/ψπ + π − system in the X(3872) decays is also investigated.
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We measure the dipion mass spectrum in X(3872)→J/ψπ+π- decays using 360pb-1 of p¯p collisions at s=1.96TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity (S13, P11, and DJ3) charmonia decaying to J/ψπ+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 D0D¯*0 molecule. Only the S13 and J/ψρ hypotheses are compatible with our data. Since S13 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.
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