3,884 research outputs found
The Case for a Reform of Regulation 17/62: Problems and Possible Solutions from a Practitioner\u27s Point of View
This Essay first describes the shortfalls of the current enforcement regime under Regulation 17 and the practical problems that undertakings experience in enforcement proceedings. It then discusses the suggestions for reform of Regulation 17. Finally, this Essay illustrates that although amendments and changes to the current procedural rules could solve some of the problems undertakings are facing in competition proceedings today, in order to address these problems effectively, changes to the underlying institutional system will be necessary
The One-Loop Five-Graviton Scattering Amplitude and Its Low-Energy Limit
A covariant path integral calculation of the even spin structure contribution
to the one-loop N-graviton scattering amplitude in the type-II superstring
theory is presented. The apparent divergence of the amplitude is resolved
by separating it into twelve independent terms corresponding to different
orders of inserting the graviton vertex operators. Each term is well defined in
an appropriate kinematic region and can be analytically continued to physical
regions where it develops branch cuts required by unitarity. The zero-slope
limit of the amplitude is performed, and the Feynman diagram content of
the low-energy field theory is examined. Both one-particle irreducible (1PI)
and one-particle redicible (1PR) graphs with massless internal states are
generated in this limit. One set of 1PI graphs has the same divergent
dependence on the cut-off as that found in the four-graviton case, and it is
proved that such graphs exist for all~. The 1PR graphs are contributed by
the poles in the world-sheet chiral Green functions.Comment: 23 pages, ITP-SB-92-6
Fast beam-ion instability simulations in the TESLA electron damping ring and the FEL beam transfer line
The Fast Beam-Ion Instability is considered potentially harmful in electron storage rings and linear colliders with short bunch spacing and high bunch charge, as it is the case in the proposed electron damping ring and the FEL beam transfer line of the future linear collider TESLA. This instability arises from interaction between a stored bunch and an ion cloud previously created by all heading bunches during a single pass. To study this effect and to determine the required vacuum conditions, a simulation code has been developed. The results of these simulation studies are presented in this paper
HERA Beam Tail Shaping by Tune Modulation
To study CP violation, the HEM-B experiment uses an internal wire target in the transverse halo of the stored HERA proton beam. Operational experience shows that the resulting interaction rates are extremely sensitive to tiny orbit jitter amplitudes. Various methods have been studied to stabilize these interaction rates by increasing diffusion in the transverse proton beam tails without affecting the luminosity at the electron-proton collider experiments ZEUS and H1. Tune modulation was found to be a promising method for this task. Experiments performed in recent years will be reported
Firesides
On various Sunday evenings, ten to fifteen I.S.U. Forestry students can be found in the home of a professor. The fireside program gives the students an opportunity to get to know each other, and their professors better
- …