118912120
Excitation fields in a superconducting global string
SummaryA model of a straight superconducting global cosmic string is examined in a setting wherein the string supports a charge/current pulse described by a travelling wave along the string. Linearized field equations are obtained for fluctuations of the scalar and vector fields of the theory, and a set of approximate particular solutions are found for the case in which the linear charge density and the current of the string have equal magnitudes. Although the equations of motion seem to suggest that the scalar and vector excitation fields are massive inside the string core, the particular solutions show that they behave as effectively massless fields which propagate at the speed of light along the string along with the primary charge/current pulse. The effect of the mass parameter is to modulate the radial profile of the excitation fields. The vector excitation field generates radial and angular components for both the electric and magnetic fields, but the particular solutions do not describe the emission or absorption of electromagnetic radiation from the string.
120927641
A parameterization forSO(3) Yang-Mills-Higgs systems
SummaryA model consisting of anSO(3) gauge field interacting with an isovector Higgs field is investigated. The gauge fields and field tensors are parameterized by the Higgs field directionality and a gauge field structure function in terms of which the magnetic field and magnetic charge density of a 't Hooft-Polyakov magnetic monopole can be simply expressed. An isovector Debye potential for a 't Hooft-Polyakov gauge field is written in terms of the gauge field structure function.
120292912
Gravitational field of a superconducting global string
SummaryThe Newtonian gravitational field of a superconducting global cosmic string is investigated using the weak-field approximation, and is found to receive contributions from the global string field, the condensate field, and the electromagnetic fields. For certain parameter ranges the gravitational field in the region exterior to the string may be everywhere repulsive, everywhere attractive, or repulsive in some regions and attractive in others. For a neutral superconducting global string there can exist a particular current for which the gravitational field of the superconducting global string approximately coincides with that of a Grand Unified Theory (GUT) scale Weyl string, and, as pointed out by Widom, Srivastava, and Redington, observed asymptotic galactic rotation velocities can be roughly explained without the introduction of any further dark-matter hypothesis.
29278740
Domain defects in strings and walls.
A type of model is considered where the Witten mechanism allows the breaking of a discrete symmetry within the core of a cosmic string or a domain wall. The formation of a real scalar field condensate results in the creation of different, but energetically degenerate, domains which are separated by massive domain defects. The defects within strings (domain kinks) are particlelike states, whereas the defects within walls (domain ribbons) resemble stringlike states. Relativistic kink-antikink pairs annihilate after their initial formation, with the release of boson radiation, and kink-antikink pairs can be created through string intercommutations. Ribbons and antiribbons can be either infinite in extent or form closed loops. Ribbon loops can be involved in fission or fusion processes producing boson radiation, and oscillating ribbon loops decay mainly through the production of boson radiation, with a negligible fraction of the released energy being emitted in the form of gravitational radiation.
8897328
Supersymmetry breaking and Fermi balls.
A simple model is presented where the disappearance of domain walls and the associated production of {open_quote}{open_quote}Fermi balls,{close_quote}{close_quote} which have been proposed as candidates for cold dark matter, are features which arise rather naturally in response to softly broken supersymmetry. {copyright} {ital 1996 The American Physical Society.}
119125621
Moduli vacuum bubbles produced by evaporating black holes
We consider a model with a toroidally compactified extra dimension giving rise to a temperature-dependent 4D effective potential with one-loop contributions due to the Casimir effect, along with a 5D cosmological constant. The forms of the effective potential at low and high temperatures indicate a possibility for the formation of a domain wall bubble, formed by the modulus scalar field, surrounding an evaporating black hole. This is viewed as an example of a recently proposed black hole vacuum bubble arising from matter-sourced moduli fields in the vicinity of an evaporating black hole [D. Green, E. Silverstein, and D. Starr, Phys. Rev. D 74, 024004 (2006)]. The black hole bubble can be highly opaque to lower-energy particles and photons, and thereby entrap them within. For high-temperature black holes, there may also be a symmetry-breaking black hole bubble of false vacuum of the type previously conjectured by Moss [I. G. Moss, Phys. Rev. D 32, 1333 (1985)], tending to reflect low-energy particles from its wall. A double bubble composed of these two different types of bubble may form around the black hole, altering the hole's emission spectrum that reaches outside observers. Smaller mass black holes that have already evaporated away could have left vacuum bubbles behind that contribute to the dark matter.
110048496
The H1 Forward Track Detector at HERA II
In order to maintain efficient tracking in the forward region of H1 after the luminosity upgrade of the HERA machine, the H1 Forward Track Detector was also upgraded. While much of the original software and techniques used for the HERA I phase could be reused, the software for pattern recognition was completely rewritten. This, along with several other improvements in hit finding and high-level track reconstruction, are described in detail together with a summary of the performance of the detector.
38275310
Time-dependent propagation of high-energy laser beams through the atmosphere: II
Various factors that can effect thermal blooming in stagnation zone situations are examined, including stagnation-zone motion, longitudinal air motion in the neighborhood of the stagnation zone, and the effects of scenario noncoplanarity. Of these effects, only the last offers reasonable hope of reducing the strong thermal blooming that normally accompanies stagnation zones; in particular, noncoplanarity should benefit multipulse more than cw beams. The methods of treating nonhorizontal winds hydrodynamically for cw and multipulse steady-state sources are discussed. Aspects of pulse “self-blooming” are also considered.
125281002
Photoproduction of $K \bar{K} \pi$ Final States in the Photon Energy Range From 20-{GeV} to 70-{GeV}
CERN-OMEGA PHOTON COLLABORATION. PHOTOPRODUCTION OF & lt;K AK PI& gt; FINAL STATES IN THE ENERGY RANGE 20 TO 70 GEV. NO EVIDENCE IS FOUND FOR THE PHOTOPRODUCTION OF PHIPRIME(1680).
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.
22405819
A search for narrow resonances in proton-proton collisions at 53 GeV centre-of-mass energy
Abstract A search for narrow resonances produced in pp collisions at the CERN ISR has been carried out using two magnetic spectrometers to measure and identify two-final-state charged hadrons. The resultant two-particle invariant mass spectra show no strong structure suggesting any new narrow resonance. The statistical significance of various enhancements seen in the data is discussed, and upper limits on the cross section times branching ratio for new particle production are presented.