209918258
Observation of an $\omega \pi^0$ State of Mass 1.25-{GeV} Produced by Photons of Energy 20-{GeV} - 70-{GeV}
17884247
Performance of the LHCb RICH detector at the LHC
The LHCb experiment has been taking data at the Large Hadron Collider (LHC) at CERN since the end of 2009. One of its key detector components is the Ring-Imaging Cherenkov (RICH) system. This provides charged particle identification over a wide momentum range, from 2–100 GeV/c. The operation and control, software, and online monitoring of the RICH system are described. The particle identification performance is presented, as measured using data from the LHC. Excellent separation of hadronic particle types (π, K, p) is achieved.
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.
121568291
Multiplicity distributions associated with charged hadron production over a range of transverse momentum and production angle at ISR energies
Abstract The charged multiplicity density M , associated with identified charged hadrons up to 3.0 GeV/ c in p T , is presented at ISR energies from 23.4 to 63.4 GeV and at 3 laboratory angles, as a function of pseudorapidity and azimuth.
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.
120611016
Nuclear photoproduction of rho mesons
Abstract Targets of Be, C, Al, Cu, Ag and Au were exposed to a tagged photon beam in the 2.75 to 4.35 GeV energy range and cross sections are presented for the reaction γA → Aϱ0. Optical spark chambers were used to examine charged particles and γ rays from the targets, so that the data are believed to be free from inelastic contamination. The results are analysed both in terms of total cross sections σ(Aγ → ϱA), and in terms of forward differential cross sections ( d σ d t ) θ=0 (γ A → ϱ A ) . From the A dependence of these cross sections we determine the total rho-nucleon cross section, σϱN, to be (22.5 ± 2.7) mb, and the absolute values of the cross sections determine the forward photoproduction cross section from a nucleon ( d σ d t ) θ=0 (γ p → ϱ p ) = (72.7 ± 8) μ b/GeV 2 . These values correspond to an assumed value αϱN = −0.2 for the ratio of the real to imaginary part of the ϱ nucleon forward scattering amplitude. The corresponding value of the photon-rho coupling constant γ ϱ 2 4π =0.65±0.16 .
122066859
Superconducting strings as sources of high-energy cosmic rays
SummaryThe possibility is explored that highly charged superconducting strings and vortons ionize neutral atoms and act as high-energy charged-particle accelerators. For strings characterized by a GUT mass scale, it is roughly estimated (neglecting radiative losses) that charged particles such as protons and heavier nuclei may reach an energy scale ≥ 1021 eV.
119297926
Real scalar fields on manifolds
A generic theory of a single real scalar field is considered, and a simple method is presented for obtaining a class of solutions to the equation of motion. These solutions are obtained from a simpler equation of motion that is generated by replacing a set of the original coordinates by a set of generalized coordinates, which are harmonic functions in the spacetime. These ansatz solutions solve the original equation of motion on manifolds that are defined by simple constraints. These manifolds, and their dynamics, are independent of the form of the scalar potential. Some scalar field solutions, and manifolds upon which they exist, are presented for Klein–Gordon and quartic potentials as examples. Solutions existing on leaves of a foliated space may allow inferences of the characteristics expected of exact bulk solutions.
121139428
Weak gravitational field of a superconducting domain wall
SummaryThe Newtonian gravitational field of a flat, infinite superconducting domain wall that can be endowed with charge and /or current is investigated using the linear approximation of general relativity. It is found that such a domain wall can possess a Newtonian gravitational field that is everywhererepulsive, everywhereattractive, orrepulsive at smaller distances andattractive at larger ones, depending upon the amount of charge and /or current supported by the wall.
119634860
Effects of radiative corrections on aU(1) cosmic string model
SummaryAn infinite-length cosmic string model consisting of aU(1) gauge field interacting with a complex scalar field is considered. When the original scalar field mass parameter is imaginary, stable cosmic string solutions can exist at the tree level of the classical theory. It is speculated that no stable solutions exist at the one-loop level of the model in this case. When the original scalar mass parameter is real-valued, no string solution exist at the tree level, but stable string solutions may exist at the one-loop level.
119080021
Fermionic and bosonic stabilizing effects for type I and type II dimension bubbles
We consider two types of "dimension bubbles", which are viewed as 4d nontopological solitons that emerge from a 5d theory with a compact extra dimension. The size of the extra dimension varies rapidly within the domain wall of the soliton. We consider the cases of type I (II) bubbles where the size of the extra dimension inside the bubble is much larger (smaller) than outside. Type I bubbles with thin domain walls can be stabilized by the entrapment of various particle modes whose masses become much smaller inside than outside the bubble. This is demonstrated here for the cases of scalar bosons, fermions, and massive vector bosons, including both Kaluza-Klein zero modes and Kaluza-Klein excitation modes. Type II bubbles expel massive particle modes but both types can be stabilized by photons. Plasma filled bubbles containing a variety of massless or nearly massless radiation modes may exist as long-lived metastable states. Furthermore, in contrast to the case with a "gravitational bag", the metric for a fluid-filled dimension bubble does not exhibit a naked singularity at the bubble's center.