Production and Decay ofΞc0atBABAR

Abstract

Using 116.1 fb(-1) of data collected by the BABAR detector, we present an analysis of xi(c)(0) production in B decays and from the cc continuum, with the xi(c)(0) decaying into omega- K+ and xi- pi+ final states. We measure the ratio of branching fractions B(xi(c)(0) --> omega- K+)/B(xi(c)(0) --> xi- pi+) spectrum is measured on and 40 MeV below the upsilon(4S) resonance. From these spectra the branching fraction product B(B --> xi(c)(0)X) x B(xi(c)(0) --> xi- pi+) is measured to be (2.11 +/- 0.19 +/- 0.25) x 10(-4), and the cross-section product sigma(e+ e- --> xi(c)(0)X) x B(xi(c)(0) --> xi- pi+) from the continuum is measured to be (388 +/- 39 +/- 41) fb at a center-of-mass energy of 10.58 GeV.

Threshold cusps and triangle singularities in hadronic reactions

“…Using identities for trigonometric functions, it is easy to verify that the above equation is equivalent to Eq. (28). For instance, Eq.…”

“…In addition, by looking at the dependence of the X(3872) → π + π − π 0 partial width on the energy of the initial state, the enhancement of the decay by the TS is evident with two sharp peaks around the neutral and charged DD * thresholds. 28 The observation of such a characteristic π + π − distribution would be a signal of the TS and the sequential decay X(3872) → (D 0D * 0 + c.c.) → π 0 D 0D0 → π + π − π 0 .…”

“…More new resonance-like structures were observed in the subsequent years. Notable examples include the charmonium-like states Y (4260) [28] and Y (4660) [29], the charged structures in the charmonium mass has kinematical singularities in the sense that their locations are determined completely by kinematical variables, such as masses and energies of the involved particles, instead of the interaction strength. They occur because intermediate particles between the initial and final states can become real propagating particles.…”

The BESIII physics programme

“…A series of high-luminosity data sets taken with E CM spanning the Y (4260) mass region provided more precise measurements of the E CM -dependence of the cross-section σ(e + e − → Y (4260) → π + π − J/ψ) [94] than any of the seven previous measurements that were based on samples of ISR events in higher energy e + e − collision data [117,127]. With an order-of-magnitude better statistical precision, the BESIII measurements revealed a previously unnoticed composite structure in the Y (4260) resonance line-shape, evident in Fig.…”

“…As a result, they can be produced directly in e + e − annihiations via a single virtual photon, that is e + e − → Y . These states, which include the Y (4260) [117], the Y (4360) [89,118], and the Y (4660) [89], have strong couplings to cc charmonium final states, in contrast to conventional vector cc charmonium states in the same energy region (such as ψ(4040), ψ(4160), and ψ(4415)) that dominantly couple to pairs of D mesons [54]. These Y states are candidates for a variety of types of nonstandard hadrons including: molecules [104,[119][120][121]; diquark-diantiquarks [122,123]; QCD-hybrids [124,125]; and hadrocharmonia [126] (See Fig.…”