122650997
THE COSMOLOGICAL CONSTANT IN STRING THEORIES
120574302
Stability of supersymmetric ground state in chiral theories
Abstract The effective action for the scalar propagator is studied in supersymmetric chiral gauge theories. The form of the scalar potential ensures the stability of the supersymmetric ground state, even for large values of the coupling constant. It is found however, that the gluino condensation tends to destabilize the system. This may signal dynamical supersymmetry breaking.
120401055
Dilaton Couplings at Large Distances
Abstract The large-distance behaviour of dilaton couplings is studied within the framework of four-dimensional heterotic superstring theories. String loop corrections violate universality of dilaton and graviton couplings, increasing dilaton couplings at large distances. This implies a serious problem for string theories, unless a non-zero dilaton mass is generated.
14387997
N = 2 HETEROTIC SUPERSTRING AND ITS DUAL THEORY IN FIVE DIMENSIONS
Abstract We study quantum effects in five dimensions in heterotic superstring theory compactified on K 3 × S 1 and analyze the conjecture that its dual effective theory is eleven-dimensional supergravity compactified on a Calabi-Yau threefold. This theory is also equivalent to type II superstring theory compactified on the same Calabi-Yau manifold, in an appropriate large volume limit. In this limit the conifold singularity disappears and is replaced by a singularity associated to enhanced gauge symmetries, as naively expected from the heterotic description. Furthermore, we exhibit the existence of additional massless states which appear in the strong coupling regime of the heterotic theory and are related to a different type of singular points on Calabi-Yau threefolds.
120318508
Low-energy softly-broken supersymmetry
Abstract We consider supersymmetric low-energy lagrangians based on the gauge group SU(3) × SU(2) × U(1) × Ũ(1), where Ũ(1) is an additional axial group a la Fayet. Models with explicit soft breaking of supersymmetry are considered as an alternative to models with axial anomalies. We argue that soft breaking can be very efficient and illustrate this with a simple example in which the introduction of a negative mass squared term for only one scalar field leads to a phenomenologically interesting model.
62835109
Lectures on heterotic-type I duality
In the last couple of years, there has been remarkable progress in understanding non-perturbative aspects of string theories. The new ingredient is the discovery of various duality symmetries; these, in particular, invert the coupling constant and exchange perturbative states with non-perturbative solitonic excitations. Since inversion of the coupling involves the Planck constant ħ, duality symmetries can be realized only at the quantum level. Once the dual models are identified, non-perturbative dynamics of one model can be studied by means of the standard perturbative techniques in the other model.
45682848
Wigglers for Control of Beam Characteristics in LEP
Eight three-block dipole wigglers will be used in LEP to maximize luminosity and control other beam parameters such as emittance, damping rates at injection, energy spread and polarization. The excitation law for constant emittance (chosen, for example, to fill the dynamic aperture) and damping partition numbers is given. In contrast to conventional wigglers where orbit perturbation is avoided by means of a series of equal fields of alternate polarity, the LEP wigglers will use unequal fields and pole lengths. This allows one to retain a high potential asymptotic polarisation level together with an increased polarisation rate. The choice of the degree of field asymmetry is imposed by limitations on the transverse dimensions of the magnets and field levels, by polarisation requirements and by cost. A practical design of the proposed wiggler is presented.
115978348
Tau-charm factory cost estimate
93472983
DESIGN OF THE LEP MAIN RING WIGGLERS
115171795
Development of a superconducting insertion quadrupole model magnet for the Large Hadron Collider
39425282
The magnets for the LHC experiments
The Large Hadron Collider (LHC) presently under construction at the European Laboratory for Particle Physics (CERN) will provide proton-proton collisions at the 14 TeV level. Each of the four approved detectors (ALICE, ATLAS, CMS, and LHCb) to be installed at the interaction points of this machine relies on a sophisticated magnet system for separation and momentum measurements of the charged particles. The magnets are being designed, manufactured, tested and installed under the technical and financial responsibility of the experiment collaborations, but must satisfy constraints imposed by the laboratory, regarding in particular the cryogenics, powering, controls, and safety. The delivery and assembly schedules are also highly constrained by the requirement to have the magnet systems fully installed before the projected commissioning of the accelerator in 2005. The report compares the salient features of these magnet systems, and of their integration into the CERN environment.