121816869
Associated photoproduction of a charmed meson and a charmed baryon
122240842
Multiplicities associated with the production of pions, kaons or protons of high transverse momentum, at the ISR
Abstract In high-energy proton-proton collisions, the mean charged multiplicity M in the central region, associated with a high-PT hadron trigger at 90°, shows a linear dependence on both ln s and PT. M is measured to depend on the type (π ± , K ± , p or p ) of the idenfied high-PT trigger particle.
24058982
The Omega Spectrometer Ring Imaging Cerenkov Detector Recent Detector Modifications and Event Analysis
A Ring Imaging Cerenkov (RICH) detector has now been successfully operated throughout a high-energy (70-200 GeV/c) photoproduction experiment at the CERN Omega Spectrometer. Recently complementary data using a hadron beam was taken with the same equipment. In each case about 20 million interactions were recorded. We discuss here features of the RICH device not yet described in previous publications and indicate by means of examples the way in which the RICH information is being used in the context of the overall experimental data analysis.
120429047
The design of the optical components and gas control systems of the CERN Omega ring imaging Cherenkov detector
Abstract A large ring imaging Cherenkov detector (RICH) has been commissioned for use at the CERN Omega spectrometer. In the first of a series of reports we begin by discussing the general design of the device and illustrate the dependence of the attainable spatial resolution and range of particle identification on its optical parameters. We then describe in detail the construction and performance of the major optical components and gas systems of the detector.
56182755
TRACK FINDING AND FITTING IN THE H1 FORWARD TRACK DETECTOR
Abstract The tracking environment in the H1 Forward Track Detector, where the hit multiplicity from proton fragments is high, is particularly hostile. The techniques and software which have been developed for pattern recognition and Kalman fitting of charged particle tracks in this region are described in detail.
121682572
Correlations between two identified charged hadrons at the CERN ISR
Abstract We have measured the value of the correlation R (h 1 , h 2 ) between two identified charged hadrons ( h = π ± , K ± , p or p ) produced in pp collisions at the CERN ISR. One hardon was produced in the forward direction and the other at a large angle. Quantum number dependent effects have been observed.
119406948
Charged vacuum bubble stability
A type of scenario is considered where electrically charged vacuum bubbles, formed from degenerate or nearly degenerate vacua separated by a thin domain wall, are cosmologically produced due to the breaking of a discrete symmetry, with the bubble charge arising from fermions residing within the domain wall. Stability issues associated with wall tension, fermion gas, and Coulombic effects for such configurations are examined. The stability of a bubble depends upon parameters such as the symmetry breaking scale and the fermion coupling. A dominance of either the Fermi gas or the Coulomb contribution may be realized under certain conditions, depending upon parameter values.
119624600
Callan-Symanzik functions and asymptotic freedom in the Lee model
The Lee model was studied in a paper by Bender and Nash in the context of determining whether the model displays asymptotic freedom. This determination is based on the calculations of the Callan-Symanzik functions. Bender and Nash have renormalized the coupling constant off the mass shell. We have performed on-shell renormalization and evaluated the Callan-Symanzik ..beta.. and ..gamma.. functions. In agreement with Bender and Nash, we find that the Lee model is asymptotically free for space-time dimensions N 4 (odd N) the model is ultraviolet stable and not asymptotically free. Finally, we employ the Weinberg relation to demonstrate the mathematical equivalence between the ..beta.. function calculated in this paper and the one presented by Bender and Nash.
119098306
Reflection and transmission at dimensional boundaries
An inhomogeneous Kaluza-Klein compactification of a higher dimensional spacetime may give rise to an effective 4D spacetime with distinct domains having different sizes of the extra dimensions. The domains are separated by domain walls generated by the extra dimensional scale factor. The scattering of electromagnetic and massive particle waves at such boundaries is examined here for models without warping or branes. We consider the limits corresponding to thin (thick) domain walls, i.e., limits where wavelengths are large (small) in comparison to wall thickness. We also obtain numerical solutions for a wall of arbitrary thickness and extract the reflection and transmission coefficients as functions of frequency. Results are obtained which qualitatively resemble those for electroweak domain walls and other ordinary domain walls for 4D theories.
119191078
Dilatonic effects near naked singularities
Static spherically symmetric solutions of 4d Brans–Dicke theory include a set of naked singularity solutions. Dilatonic effects near the naked singularities result in either a shielding or an antishielding effect from intruding massive test particles. One result is that for a portion of the solution parameter space, no communication between the singularity and a distant observer is possible via massive particle exchanges. Kaluza–Klein gravity is considered as a special case.
119478222
Destabilization of neutron stars by type I dimension bubbles
An inhomogeneous compactification of a higher-dimensional spacetime can result in the formation of type I dimension bubbles, i.e., nontopological solitons which tend to absorb and entrap massive particle modes. We consider possible consequences of a neutron star that harbors such a soliton. The astrophysical outcome depends upon the model parameters for the dimension bubble, with a special sensitivity to the bubble's energy scale. For relatively small energy scales, the bubble tends to rapidly consume the star without forming a black hole. For larger energy scales, the bubble grows to a critical mass, then forms a black hole within the star, which subsequently causes the remaining star to collapse. It is possible that the latter scenario is associated with core collapse explosions and gamma ray bursts.