18544496
Speculations on AdS/CFT at all orders in 1/N
A simple ansatz is considered for the scalar field dependence of the part of the fourgraviton scattering amplitude in type IIB superstring theory in AdS5 × S that comes from the (Weyl tensor) term. This incorporates SL(2, ZZ) duality at every order of the α/L expansion (where L is the AdS5 scale). The relative coefficients in this series are determined, via the AdS/CFT correspondence, by the contribution of a single Yang–Mills instanton to the correlation function of four energy-momentum tensors in the N = 4 SU(N) Yang–Mills theory, which is known exactly for all values of N . The resulting series is not Borel summable, which suggests that some puzzling contributions that are nonperturbative in α/L = (g Y M N) (where g Y M is the Yang–Mills coupling constant) may be present in the complete expression.
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.
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.
121755839
PHASE CONTOURS AND BOOTSTRAPS. I.
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.
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.
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.
118224501
An update on passive correctors for the SSC dipole magnets
The concept of correction of the magnetization sextupole became a topic of discussion as soon as it was realized that superconductor magnetization could have a serious effect on the SSC beam during injection. Several methods of correction were proposed. These included (1) correction with active bore tube windings like those on the HERA machine which correct out magnetization sextupole and the sextupole due to iron saturation, (2) correction with persistent sextupole windings mounted on the bore tube (3) correction using passive superconductor (4) correction using ferromagnetic material, and (5) correction using oriented magnetized materials. This report deals with the use of passive superconductor to correct the magnetization sextupole. Two basic methods are explored in this report: (1) One can correct the magnetization sextupole by changing the diameter of the superconductor filaments in one or more blocks of the SSC dipole. (2) One can correct the magnetization sextupole and decapole by mounting passive superconducting wires on the inside of the SSC dipole coil bore. In addition, an assessment of the contribution of each conductor in the dipole to the magnetization sextupole and decapole is shown. 38 refs, 25 figs., 15 tabs.
122853350
A thin superconducting solenoid for use in a phase rotation induction linac
One of the proposals for delivering a cooled muon beam to a muon collider or a high intensity neutrino source uses an induction linac to phase rotate the muons that result from the decay of pions produced by a high intensity proton beam on a target. An induction linac with an acceleration gradient of 2 MV per meter is proposed to produce bunches of muons that have a momentum of 200 MeV/c. The induction accelerator is assembled around the 3 T superconducting solenoids needed to contain the muon beam. The superconducting solenoid must have a warm 100 mm gap at 1000 mm intervals down the phase rotation channel. The acceleration structure for the induction linac is around this gap. The superconducting solenoid will have an inside warm radius of 201 mm. The thickness of the superconducting magnet and its cryostat must be about 60 mm near the acceleration gap. An access region of 85 mm between induction linac sections is allowed for the superconducting coil cold mass supports, the electrical leads and the supply of cryogenic cooling. This report presents a design for a 3 T phase rotation induction linac superconducting magnet system, its cryostat, and its cooling system.
28498071
Magnet system design with cost optimization
The problem of optimizing the design of magnet systems to simultaneously satisfy a set of constraint equations for field, geometry, protection, and stability while minimizing the total system cost is considered. A mathematical description of the problem is given, along with details concerning possible constraint algorithms and cost functions. Rules for the optimal selection of magnet technology (potted, ventilated, and cable-in-conduit coils) are presented. The resulting sets of equations can be solved by different numerical methods; the final choice is based on considerations of functional form as well as computational speed and accuracy. Depending on the choice of constraint equations, the resulting problem may or may not be smooth, and may or may not admit multiple minima. The choice of minimization algorithm can be tailored to the situation at hand to yield optimal performance. We present results pertaining to an alternating-field solenoid system being considered by the MuCool collaboration. The system design requires consideration of field profile, magnet stability, magnet structure, and protection, as well as total cost. A key application of the optimization code is the analysis of cost trade-off with respect to the imposed constraints, and examples are given in the alternating-solenoid case.