1267166
Can fermions save large N dimensional reduction
This paper explores whether Eguchi-Kawai reduction for gauge theories with adjoint fermions is valid. The Eguchi-Kawai reduction relates gauge theories in different numbers of dimensions in the large N limit provided that certain conditions are met. In principle, this relation opens up the possibility of learning about the dynamics of 4D gauge theories through techniques only available in lower dimensions. Dimensional reduction can be understood as a special case of large N equivalence between theories related by an orbifold projection. In this work, we focus on the simplest case of dimensional reduction, relating a 4D gauge theory to a 3D gauge theory via an orbifold projection. A necessary condition for the large N equivalence between the 4D and 3D theories to hold is that certain discrete symmetries in the two theories must not be broken spontaneously. In pure 4D Yang-Mills theory, these symmetries break spontaneously as the size of one of the spacetime dimensions shrinks. An analysis of the effect of adjoint fermions on the relevant symmetries of the 4D theory shows that the fermions help stabilize the symmetries. We consider the same problem from the point of view of the lower dimensional 3D theory and find that, surprisingly, adjoint fermions are not generally enough to stabilize the necessary symmetries of the 3D theory. In fact, a rich phase diagram arises, with a complicated pattern of symmetry breaking. We discuss the possible causes and consequences of this finding.
119190019
An effective-field-theory analysis of low-energy parity-violation in nucleon–nucleon scattering
Abstract We analyze parity-violating nucleon–nucleon scattering at energies E m π 2 / M using the effective field theory appropriate for this regime. The minimal Lagrangian for short-range parity-violating NN interactions is written in an operator basis that encodes the five partial-wave transitions that dominate at these energies. We calculate the leading-order relationships between parity-violating NN asymmetries and the coefficients in the Lagrangian and also discuss the size of sub-leading corrections. We conclude with a discussion of further observables needed to completely determine the leading-order Lagrangian.
85525002
The Theory of Parity Violation in Few-Nucleon Systems
Abstract We review recent progress in the theoretical description of hadronic parity violation in few-nucleon systems. After introducing the different methods that have been used to study parity-violating observables we discuss the available calculations for reactions with up to five nucleons. Particular emphasis is put on effective field theory calculations where they exist, but earlier and complementary approaches are also presented. We hope this review will serve as a guide for those who wish to know what calculations are available and what further calculations need to be completed before we can claim to have a comprehensive picture of parity violation in few nucleon systems.
54173137
Even- and odd-parity charmed meson masses in heavy hadron chiral perturbation theory
We derive mass formulae for the ground state, J P = 0 − and 1 − , and first excited even-parity, J P = 0 + and 1 + , charmed mesons including one loop chiral corrections and O(1/mc) counterterms in heavy hadron chiral perturbation theory. We show that including these counterterms is critical for fitting the current data. We find that certain parameter relations in the parity doubling model are not renormalized at one loop, providing a natural explanation for the observed equality of the hyperfine splittings of ground state and excited doublets.
118865932
Weak Radiative B Meson Decay
Weak radiative B meson decays, → γX s have a B meson decaying to a hard photon (i.e., E γ ≳ 2 GeV) and strange hadronic final states X s . The prediction of the standard model (with minimal particle content) for the rate for this process is reviewed. Particular attention is paid to the role of strong interaction corrections, which have a significant impact on the rate.
18643814
SU(3) predictions for weak decays of doubly heavy baryons, including SU(3) breaking terms
We find expressions for the weak decay amplitudes of baryons containing two b quarks (or one b and one c quark -- many relationship are the same) in terms of unknown reduced matrix elements. This project was originally motivated by the request of the FNAL Run II b Physics Workshop organizers for a guide to experimentalists in their search for as yet unobserved hadrons. We include an analysis of linear SU(3) breaking terms in addition to relationships generated by unbroken SU(3) symmetry, and relate these to expressions in terms of the complete set of possible reduced matrix elements.
110934427
Experience in construction and testing of plastic limited streamer chambers
The manufacture and testing of multicell limited streamer chambers for use in the hadron calorimeter of the OPAL detector and LEP (Large Electron Positron Collider) are described. All operations, from chamber cathode coating to the testing of completed subassemblies, have been performed under the same roof. With reasonable care and quality control, the established technology produced chambers several meters long with an overall success rate of about 90%. Treatment of the carbon coating with Breox B-35 was effective in eliminating uncertainties in the cathode performance. >
73632090
Stereo Spectrum of UHECR showers at the HiRes Detector
We present a measurement of the energy spectrum of UHECR showers. This measurement uses the two HiRes detector sites separated by 12.6 km to perform stereoscopic observations of UHECR air showers. The technique of stereoscopic reconstruction of the shower geometry and longitudinal profile is described. The resolution of reconstructed shower parameters using these techniques has been estimated using a detector simulation. Using the independently measured shower profiles from each detector site the energy resolution has also been measured. The detector aperture has been estimated by using the detector simulation. The energy distribution and resultant energy spectrum will be shown.
15877362
A fiber-optic-based calibration system for the High Resolution Fly's Eye cosmic ray observatory
Abstract This article describes the fiber-optic-based calibration system installed at the High Resolution Fly's Eye (HiRes) astro-particle physics observatory. The HiRes detectors measure ultra violet scintillation light from distant extensive air showers. This automated calibration system delivers light from a frequency tripled 355 nm YAG laser to the 10,752 photo-multiplier tubes of the 42 HiRes-II detectors.
67767062
Measurement of the Flux of UHE Cosmic Rays by the HiRes Detectors Observing in both Monocular and Stereo- scopic Modes
The High Resolution Fly’s Eye Detector (HiRes) detects and measures properties of ultra high energy cosmic rays (UHECR). The HiRes detector exploits the air fluorescence technique that uses the atmosphere as a calorimeter. A brief description of this technique and how it is used by the HiRes detector will be given in this paper. The HiRes detector has been operational with two detector sites separated by 12.6 km since the fall of 1999. The two separated “eyes” enable the HiRes detector to obtain stereoscopic observations of the air showers. We also have a data set obtained with the first of the 2 sites from a total of 4.0 years of observations in monocular mode. Preliminary results from both the monocular and stereo analysis will be described.
124438200
Preliminary stereo results from the High Resolution Fly's Eye cosmic ray observatory
The High Resolution Fly's Eye Cosmic Ray Ob- servatory consists of two detector sites located on hilltops in the western desert of Utah. The two sites are separated by 12.6 km. Stereoscopic observations from the two sites en- able the location of air showers to be more accurately recon- structed by using triangulation. The improved geometrical reconstruction provides for a more precise measurement of both the energy of the primary cosmic ray particle and the depth of the shower maximum. Preliminary results from ap- proximately 1000 hours of stereo on-time will be shown.