121122211
Reciprocal space-time and momentum-space singularities in the narrow resonance approximation
Abstract A general scheme is proposed which makes explicit the relationship between the singularities of off-shell amplitudes in position-space and momentum-space in the narrow resonnace approximation. In some ways this may be viewed as a duality scheme for amplitudes involving external quarks, in which narrow resonances in certain channels build the Fourier transform of power singularities in x 2 ( x μ being a position vector). This scheme is made precise by dual string off-shell amplitudes. As well as highlighting possible connections between the general dual framework and the structure of confined field theories we are able to pinpoint certain grave shortcomings of present dual models.
121755839
PHASE CONTOURS AND BOOTSTRAPS. I.
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.
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.
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.
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.
40872680
A large superconducting thin solenoid for the STAR experiment at RHIC
The author describes the 4.4-m, warm bore diameter, thin superconducting solenoid, for the proposed Solenoidal Tracker at RHIC (STAR) experiment at the Relativistic Heavy Ion Collider (RHIC). The STAR solenoid will generate a very uniform central magnetic induction of 0.5 T within a space which is 4.0 m in diameter by 4.2 m long. The solenoid and its cryostat will be 0.7 radiation lengths thick over a length of 5.45 m, about the center of the magnet, making it the largest solenoid less than one radiation length to be built. A proposed design for the solenoid and cryostat, its flux return iron, its cryogenic system, and its power supply and quench protection system is described.<<ETX>>
29897332
High-gradient normal-conducting RF structures for muon cooling channels
We present a status report on the research and development of high-gradient normal-conducting RF structures for the ionization cooling of rations in a neutrino factory or muon collider. High-gradient RF structures are required in regions enclosed in strong focussing solenoidal magnets, precluding the application of superconducting RF technology. We propose using linear accelerating structures, with individual cells electromagnetically isolated, to achieve the required gradients of over 15 MV/m at 201 MHz and 30 MV/m at 805 MHz. Each cell will be powered independently, and cell length and drive phase adjusted to optimise shunt impedance of the assembled structure. This efficient design allows for relatively small field enhancement on the structure walls, and an accelerating field approximately 1.7 times greater than the peak surface field. The electromagnetic boundary of each cell may be provided by a thin Be sheet, or an assembly of thin-walled metal tubes. Use of thin, low-Z materials will allow passage of the muon beams without significant deterioration in beam quality due to scattering. R&D in design and analysis of robust structures that will operate under large electric and magnetic fields and RF current heating are discussed, including the experimental program based in a high-power test laboratory developed for this purpose.
122023958
Tests on large diameter superconducting solenoids designed for colliding beam accelerators
Two prototype large diameter thin coil solenoids which use the mechanical structure to moderate quenches, have been built and systematically tested. The solenoids are cooled by two phase helium flowing in tubes which form a part of the coil structure. The coils have been tested by inducing a series of quenches at various currents. The results of these tests are given in this paper.
39829406
The Helium Cooling System and Cold Mass Support System for the MICE Coupling Solenoid
The MICE cooling channel consists of alternating three absorber focus coil module (AFC) and two RF coupling coil module (RFCC) where the process of muon cooling and reacceleration occurs. The RFCC module comprises a superconducting coupling solenoid mounted around four conventional conducting 201.25 MHz closed RF cavities and producing up to 2.2 T magnetic field on the centerline. The coupling coil magnetic field is to produce a low muon beam beta function in order to keep the beam within the RF cavities. The magnet is to be built using commercial niobium titanium MRI conductors and cooled by pulse tube coolers that produce 1.5 W of cooling capacity at 4.2 K each. A self-centering support system is applied for the coupling magnet cold mass support, which is designed to carry a longitudinal force up to 500 kN. This report will describe the updated design for the MICE coupling magnet. The cold mass support system and helium cooling system are discussed in detail.
56416083
A compact-high performance NLC damping ring using high magnetic field bending magnets
We describe a 1.5 GeV damping ring for very low emittance e/sup /spl plusmn// beams that can be used for the NLC. A key feature of this system is the use of 7 T bending magnets to greatly reduce the size and cost of the storage ring as well as the tune and the damping ring while increasing the acceptance. We present only a preliminary study here.