Working group report: Collider Physics

This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology (WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these problems by the subgroups formed during the workshop is included in this report.     

Search for the CP forbidden decay eta-->4pi(0)

We report the first determination of the upper limit for the branching ratio of the CP forbidden decay eta-->4pi(0). No events were observed in a sample of 3.0x10(7) eta decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated pi(-) beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B(eta-->4pi(0))相似文献   

On the singularity of Green's tensor for a perfectly conducting semi-infinite cone

This paper is intended to clarify a misunderstanding concerningthe source singularity of the electric Green's tensor for aperfectly conducting semi-infinite cone of circular cross-section.Tai's series expansion of the Green's tensor is known to lacka singular term at the source region. Jones has reconstructedthe solution to this problem and has pointed out the differencebetween his result and that of Tai. The aim of our paper isto demonstrate that, although Jones's closed-form solution iscorrect, there is a mistake in his comparison with Tai's seriessolution. We conclude that one of the two additional singularterms that Jones claims as missing from Tai's formula must beomitted. Besides, we compare Jones's closed-form solution withSmyshlyaev's solution to the very same problem. We concludethat the magnetic field expressions given by Jones and Smyshlyaevcoincide, but a singular term is missing from Smyshlyaev's expressionfor the electric field.     

Scattering by small defects in the neighbourhood of a fluid-solid interface

The scattering of incident plane elastic waves by a varietyof different defects that lie upon a fluid-solid interface isconsidered here using matched asymptotic expansions. The expansionscheme is developed in terms of a parameter , the ratio of typicaldefect length scale to a typical wavelength of the incidentfield, taken to be small. Three different canonical situations occur and these are illustratedvia three specific examples treated here: a rigid strut, anedge crack, and a rigid strip. In each case the leading-ordermatching is performed to identify the leading-order contributionof the defect to the acoustic field in the far field. In particular,each defect is identified with a source of dipole response ininterfacial stress of displacement. It is shown in the limit as s<<s1 that in the inner problemsthe fluid and solid pieces uncouple in a particularly convenientmanner allowing analytical solutions to be deduced. These arethen matched with appropriate outer solutions.     

Dynamics of the pi(-)p-->pi(0)pi(0)n reaction for p(pi(-))<750 MeV/c

Data are presented for the reaction pi(-)p-->pi(0)pi(0)n in the range from threshold to p(pi(-))=750 MeV/c. The systematics of the data and multipole analyses are examined for sensitivity to a f(0)(600) ("sigma") meson. A one-pion-exchange mechanism is found to be very weak, or absent. The reaction appears to become dominated by sequential pi(0) decays through the Delta(1232) resonance as the beam momentum increases, along with substantial interference effects from several competing mechanisms.