Observation and Properties of theX(3872)Decaying toJ/ψπ+π−in

Abstract

Observation and Properties of the X(3872) Decaying to J/ψ π + π − in pp Collisions at √ s= 1.96 TeV

The Mass and Current-Meson Coupling Constant of the Exotic X(3872) State from QCD Sum Rules

“…confirmed later in some other experiments [2][3][4]. The exotic states were produced and observed in B meson decays, in the e + e − and pp annihilations, in the double charmonium production processes, in the two-photon fusion and pp collisions.…”

“…Later the X(3872) was observed also through direct production mode in pp annihilation [2,3], as well as in the e + e − annihilation and pp collisions [13]. The assigned quantum numbers to X state are 1 ++ , its average mass extracted from different experiments is m X = (3871.69 ± 0.17) MeV , and the decay width was estimated as Γ < 1.2 MeV [10,19,20].…”

Tetraquarks in the 1/N expansion and meson-meson resonances

“…The series of X, Y, Z resonances, initiated by Belle with the X(3872) [1] resonance later confirmed by BaBar [2], CDF [3], D0 [4], LHCb [5], CMS [6], has recently been enlarged by the observation of two, hidden charm, pentaquarks P discovered by LHCb [7]. The X, Y, Z, P, hadrons have received different interpretations, under the names of tetraquarks/pentaquarks [8][9][10][11][12][13][14], 1 molecules or resonances [15][16][17][18][19] 2 or cusp effects of different kinds [20].…”

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

“…The discovery of the X(3872) resonance by the Belle experiment in 2003 [1] and its subsequent confirmation by BaBar, CDF, and D0 [2][3][4] has attracted a large interest in "exotic" quarkonium spectroscopy since it was the first observation of an unexpected charmonium candidate. Many new unconventional states with masses above the open-charm or open-bottom thresholds, m > m(DD) and m > m(BB), respectively, have been observed [5].…”