The authors report the observation of a narrow state decaying into J/???− and produced in 220 pb−1 of {bar p}p collisions at √s = 1.96 TeV in the CDF II experiment. They observe 730 ± 90 decays. The mass is measured to be 3871.3 ± 0.7(stat) ± 0.4(syst) MeV/c2, with an observed width consistent with the detector resolution. This is in agreement with the recent observation by the Belle Collaboration of the X(3872) meson.

The authors measure the dipion mass spectrum in X(3872) → J/???− decays using 360 pb−1 of {bar p}p 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{sub J}) charmonia decaying to J/??+?−, as well as event C-parity states in which the pions are from?° decay. The latter case also encompasses exotic interpretations, such as a D°{bar D}*° molecule. Only the 3S1 and J/?? hypotheses are compatible with the data. Since 3S1 is untenable on other grounds, decay via J/?? is favored, which implies C = +1 for the X(3872). Models for different J/?-? angular momenta L are considered. Flexibility in the models, especially the introduction of?-? interference, enable good descriptions of the data for both L = 0 and 1.

We report the observation of a narrow structure, $X(5568)$, in the decay sequence $X(5568) \rightarrow B_s^0 \pi^{\pm}$, $B_s^0 \rightarrow J/\psi \phi$, $J/\psi\rightarrow \mu^+ \mu^-$, $\phi \rightarrow K^+K^-$. This is the first observation of a hadronic state with valence quarks of four different flavors. The mass and natural width of the new state are measured to be $m = 5567.8 \pm 2.9 {\rm \thinspace (stat)} ^{+0.9}_{-1.9} {\rm \thinspace (syst)}$ MeV/$c^2$ and $\Gamma = 21.9 \pm 6.4 {\rm \thinspace (stat)} ^{+5.0}_{-2.5} {\rm \thinspace (syst)} $ MeV/$c^2$, and the significance including look-elsewhere effect and systematic uncertainties is 5.1$\sigma$. The observation is based on$10.4~\rm{fb^{-1}}$ of $p \overline p $ collision data at $\sqrt{s}$ = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.

Using pp collision data collected at sqrt(s ) = 7 TeV in 2010 and 2011with the ATLAS detector (A Toroidal LHC ApparatuS), corresponding to an integrated luminosity of 2.44 fb-1 , the J/PsiPi+Pi- combinations have been studied. The selection criteria have been developed, the detection efficiency of the Xc (3872) signal has been evaluated, and the systematic errors have been identified. Both the Psi(2S ) and the Xc (3872) signals are observed in the J/PsiPi+Pi- mass spectrum. The detection of the charmonium-like X, Y, Zstates is feasible with the ATLAS detector at the Large Hadron Collider (LHC). Other than the Psi(2 S ) and the Xc (3872) signals, there is no evidence for any significant enhancement in the J/PsiPi+Pi- mass spectrum. This dissertation research establishes that ATLAS can detect Xc (3872) like new particles in the J/PsiPi+Pi- final state, and with current data sample, no new states have been observed in this study.

We present results of a search for the X(3872) in B° → X(3872)K{sub S}°, X(3872) → J/???−, improved measurements of B− → X(3872)K−, and a study of the J/??+?− mass region above the X(3872). We use 232 million B{bar B} pairs collected at the?(4S) resonance with the BABAR detector at the PEP-II e+e− asymmetric-energy storage rings. The results include the 90% confidence interval 1.34 x 10−6