Evidence for the Existence of aZ*

Abstract

It should be noted that d(a t 2 +a 2 2 )/dt and dSl/dt both behave like {a^a^) 2 as one approaches the point of bifurcation. 7 The singularity which this expression manifests at £2 2 = 4B n (where dynamical instability sets in) is spurious: Eq. (15), without the substitution (16), leads to the result a= £2±(0.4Z?£2 5 )Results of a phase-shift analysis with and without the use of a Regge-pole model in K + p elastic scattering from 0.86 to 1.95 GeV/c are described. We have obtained four possible solutions, all of which indicate resonantlike behavior in one partial-wave amplitude. Three of our solutions yield a P 3 / 2 partial wave with a behavior consistent with the Breit-Wigner resonance formula. The properties of such a Z* resonance are described.We have reported earlier a preliminary phaseshift analysis of K + p elastic-scattering data from 0.86 to 1.95 GeV/c. 1 Since then an extensive random search for solutions has been carried out. The data used in the analysis include new polarization measurements 2 at 1.89 GeV/c which we obtained using a butanol-alcohol target 3 at 26 kG. These new measurements are in good agreement with the old ones which were taken with a lanthanum-magnesium-nitrate target. We have also included recent polarization data at 0.86 and 0.96 GeV/c by Andersson et al. 1 We have obtained four possible solutions, all of which indicate res-onantlike behavior in one partial-wave amplitude. The same results were obtained when analysis was repeated using predictions for high partial waves from a Regge-pole model.In our energy-independent analysis, we have found typically about 50 solutions (XV^DF^ 2.5) at each momentum. By examining all the partial waves simultaneously, we noted that these solutions clustered into several areas on Argand diagrams. To select the best of these, we first required that each group vary with increasing momentum on the Argand diagram in a smooth, continuous way in each partial wave; this test elimi- Table I. Outline of phase-shift solutions.

Partial-wave analysis ofK+-nucleon scattering

“…Hashimoto [15] observed a resonance-like structure in the T=0 D3/2 wave which had been seen before [19,25,26]. While we see a loop in the Argand diagram, it is less pronounced than what he saw.…”

“…Leaving aside many of the earlier analyses [16,17,18,23,24,25,26,27,28] there are three modern analyses with which we compare.…”

“…There have been very little data taken (but see [4,5]) in an ordinary sense since the most recent partial-wave analyses [15,16,17,18,19,20,21,22,23,24,25,26,27,28]. The suggestion of the existence of a possible pentaquark resonance (see Ref.…”

Pentaquark Resonances From Collision Times

“…S. Kato et al 22 obtained four possible solutions from a phase shift analysis of K + p elastic scattering and on the basis of Argand diagrams concluded on a possible mass of the Z * around 1.9 to 2 GeV and Γ ∼ 130 − 250 MeV in the P 13 partial wave. This work was followed by two articles by Aaron et al 23 which reported evidence for the Z * 's in the D 03 , S 01 and P 01 partial waves using Argand diagrams and speed plots.…”

Review of Recent Work on Narrow Resonance Models

“…Additional work relevant to this section can be found in Kato et al (1969), Neville (1969), Schmid (1969b), Schwimmer (1969), and Yellin (1969c) Footnotes for Section VIII 8a) We e:mphasize that these duality diagrams are not the dual diagrams connected with the singularity structure of Feynman diagrams.…”