E852 reports a bump in pi p -> omega pi p in the exotic 2+- wave.

Flavour Singlet Hybrid Decay Mode Computed on the Lattice

The UKQCD Collaboration have measured a 100 MeV width for heavy hybrid decay to a heavy hidden flavour meson + a light flavour singlet meson. If confirmed, this result will cast serious doubt on all current hybrid decay models.

pi₁(1600) Seen in New Channel

E852 reports seeing the pi₁(1600) in eta' pi^- with a mass of 1597(10)(45) and width 340(40)(50).

Possible ssg Partner to pi(1800) Found

BES data on $J/\psi \to \gamma (K^{\pm} K_S^0 \pi^{\mp})$ are presented. At a $K\bar{K}\pi$ mass of $\sim 2040$ MeV, there is a second peak with width $\sim 400$ MeV; $J^P = 0^-$ is preferred over $1^+$ and $2^-$ respectively by 5.2 and 6.8 standard deviations. It is a possible candidate for a $0^-$ $s\bar sg$ hybrid partner of $\pi(1800)$.

hep-ex/0002007

Lattice Glueball Spectrum

From Morningstar and Peardon

1^-+ Exotic Hybrid seen by E852 at 1593 MeV

The quantum number-exotic hybrid was seen in the pi rho channel with a resonance mass of 1593 +- 8 ⁺²⁹_-47 MeV and a width of 168 +- 20 ⁺¹⁵⁰_-12 MeV.

Lattice Hybrid Wavefunction

The MILC collaboration (hep-let/9809087) makes a preliminary measurement of the 1^-+ hybrid wavefunction in Coulomb gauge.

New Results from VES

The VES Collaboration (hep-ex/9810013) report evidence for a 0^-+ resonance at 1.74 GeV with a width of 259(19,60) MeV. This does not appear to be the pi(1800). It is tempting to speculate that the two states are the expected 3 ¹S₀ quarkonium state and a hybrid.

A resonance was seen in b₁ pi with exotic quantum numbers 1^-+ at 1.7 GeV with a width of roughly 500 MeV.

Meson Mass Splittings

Also from Juge, Kuti, and Morningstar, hep-lat/9809098. The following table shows various conventional and hybrid masses as calculated from NRQCD and in the Born Oppenheimer approximation. The differences may be taken as an indication of the importance of retardation effects.

state	n L (glue)	NRQCD	Born Oppenheimer
chi_b	1 P (Sigma_g+)	0.96(1)	0.872(5)
	2 S (Sigma_g+)	1.30(1)	1.224(3)
1-+	1 P (Pi_u)	3.29(5)	3.166(3)
1-+'	2 P (Pi_u)	4.20(7)	3.772(2)
0+-	1 P (Pi_u)	3.51(8)	3.166(3)
0*++	1 S (Sigma_u-)	3.56(8)	3.807(12)

Adiabatic Hybrid Surfaces

Juge et al. have generated beautiful lattice adiabatic hybrid potentials. Postscript version.