119432585
Point-like states for type 2b superstrings☆
Abstract This paper considers closed-string states of type 2b superstring theory in which the whole string is localized at a single pointin superspace. Correlation functions of these (scalar and pseudoscalar) states possess an infinite number of position-spacesingularities inside and on the light-cone as well as a space-like singularity outside the light-cone.
121755839
PHASE CONTOURS AND BOOTSTRAPS. I.
123230985
Off-shell states in the dual model
Abstract We present a class of Lorentz invariant, gauge invariant off-shell amplitudes for the ordinary Veneziano and Ramond-Neveu-Schwarz dual models. They correspond to interactions with the string which are local in space-time.
9607753
Anomalous creation of branes
In certain circumstances when two branes pass through each other a third brane is produced stretching between them. We explain this phenomenon by the use of chains of dualities and the inflow of charge that is required for the absence of chiral gauge anomalies when pairs of D-branes intersect.
121062482
N=4 Yang-Mills and N=8 Supergravity as Limits of String Theories
The formulation of supersymmetric string theories in ten dimensions is generalized to incorporate compactified dimensions. Expressions for the one-loop four-particle S -matrix elements of N = 4 Yang-Mills and N = 8 supergravity in four dimensions are obtained by studying the string-theory loop amplitudes in the limit that the radii of the compactified dimensions and the Regge slope parameter simultaneously approach zero. If certain patterns that emerge should persist in the higher orders of perturbation theory, then N = 4 Yang-Mills in four dimensions would be ultraviolet finite to all orders, whereas N = 8 supergravity in four dimensions would have ultraviolet divergences starting at three loops.
120539667
Anomaly cancellations in supersymmetric D = 10 gauge theory and superstring theory☆
Abstract Supersymmetric ten-dimensional Yang-Mills theory coupled to N = 1, D = 10 supergravity has gauge and gravitational anomalies that can be partially cancelled by the addition of suitable local interactions. The remaining pieces of all the anomalies cancel if the gauge group is SO(32) or E 8 × E 8 . These cancellations are automatically incorporated in the type I superstring theory based on SO(32). A superstring theory for E 8 × E 8 has not yet been constructed.
121321569
A report on Russian magnet technology for use in phi factory and light source bending magnets
118295670
Progress on Superconducting Magnets for the MICE Cooling Channel
MICE Note 274 Progress on the Superconducting Magnets for the MICE Cooling Channel M. A. Green a , S. P. Virostek a , D. Li a , M. S. Zisman a , L. Wang b , H. Pan b , H. Wu b , X. L. Guo b , F. Y. Xu b , X. K. Liu, S. X. Zheng b , T. Bradshaw c , D. E. Baynham c , J. Cobb d , W. Lau d , P. Lau d , and S. Q. Yang d , a) Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA b) Institute of Cryogenic and Superconductivity Technology, HIT, Harbin, China c) Rutherford Appleton Laboratory, Chilton Didcot OX11-0QX, UK d) Physics Department Design Office, Oxford University, Oxford OX1-3RH, UK Corresponding Author: Michael A. Green at magreen@lbl.gov Abstract. The muon ionization cooling experiment (MICE) consists of a target, a beam line, a pion decay channel, the MICE cooling channel. Superconducting magnets are used in the pion decay channel and the MICE cooling channel. This report describes the MICE cooling channel magnets and the progress in the design and fabrication of these magnets. The MICE cooling channel consists of three types of superconducting solenoids; the spectrometer solenoids, the coupling solenoids and the focusing solenoids. The three types of magnets are being fabricated in the United States, China, and the United Kingdom respectively. The spectrometer magnets are used to analyze the muon beam before and after muon cooling. The coupling magnets couple the focusing sections and keep the muon beam contained within the iris of the RF cavities that are used to recover the muon momentum lost during ionization cooling. The focusing magnets focus the muon beam in the center of a liquid hydrogen absorber. The first of the cooling channel magnets will be operational in MICE in the spring of 2010. 1. Introduction to the MICE Cooling Channel The next generation of particle physics accelerators will involve the acceleration and collision of high- energy leptons. There are limits on how much the lowest mass stable lepton (electrons and positrons with a rest mass of 0.51 MeV) can be bent in a magnetic field. The next lowest mass lepton is the muon (rest mass ~100 MeV). High-energy muons can be bent without the synchrotron radiation that comes from bending electrons or positrons. Muons are produced from the decay of pions, which are produced when protons collide with a fixed target. Muons produced this way have a high emittance. The development of a neutrino factory or a muon collider requires that muon-beams be cooled (reducing their emittance by removing the transverse momentum while retaining the momentum in the direction of the beam). Because a muon has a short lifetime (~2.1 µs at rest), the methods used for cooling positrons and anti protons cannot be employed. The only method that can be applied that will cool muons within their lifetime is ionization cooling. Demonstrating muon ionization cooling is essential to the development of muon accelerators and storage rings [1], [2]. The muon ionization cooling experiment (MICE) is designed to demonstrate muon cooling in a magnet configuration that is useful for a neutrino factory [3], [4].
109198934
A Large Superconducting Detector Magnet Without An Iron Return Path
This paper describes a detector magnet which returns flux between the coils rather than through an iron return path. This actively shielded, uniform field 2 T magnet can be fabricated in separate parts which can be manufactured on the SSC site. This magnet can be built so that central field is uniform enough to permit a TPC detector to be used without iron poles. The field outside of the coil can be made to fall of as R−N power where N approaches 9. A major advantage of the magnet described in the paper is that there is no pole piece to block the particle jets emanating from the collision region in the forward and backward directions. Inexpensive materials such as earth and concrete can be used to provide the mass needed to analyze particles such as mu mesons. As a result, problems such as experimental hall subsidence can be reduced. Perhaps the cost of such an experiment can also be reduced. This type of magnet would require experimenters to rethink their experimental concepts.
36002879
Computer Simulation of the Interaction of a Superconducting Synchrotron Magnet Good Field Region with a Particle Beam
This paper illustrates how the results of several magnetic field calculation computer programs can be combined to form a single graphical representation of magnetic field quality within the aperture of a superconducting accelerator magnet. The graphical technique can be applied on a magnet by magnet basis over a range of current excitations. The paper illustrates the value of such graphics when the accelerator beam profile is shown within the simulated magnet bore.
118834673
A Design for a Combined Function Superconducting Dipole for a Muon Collider FFAG Accelerator
The acceleration stages for a muon collider require that the muons be accelerated within a given ring in fewer than twenty turns. One type of accelerator that appears to be attractive for a synchrotron that accelerates the muon a factor of four in energy in a few turns is the Fixed Field Alternating Gradient (FFAG) type of accelerator. As the energy of the muon beam increases, the muons move toward a higher field region of a DC combined function dipole. The following dipole and quadrupole magnet characteristics are required for a muon FFAG machine to be successful: (1) The dipole will be a fixed field dipole with an impressed quadrupole and sextupole field. There may or may not be separate quadrupoles that mayor may not have added sextupole windings. (2) The horizontal aperture of the required good field region is wider than the vertical aperture of the required good field region. (3) The magnet is relatively short, so that the conventional SSC type of superconducting dipole or quadrupole ends can not be used. The field at the end of the magnet must fall off abruptly within the distance of less than one vertical aperture. For a magnet that is 400more » mm long, the end region can be no more than 80 mm long. (4) The structure of the integrated field within the end region must be the same as the structure of the two-dimensional filed at the center of the magnet. A very preliminary design concept for a FFAG combined function dipole is presented in this paper.« less