14055711
Duality of N = 2 heterotic-type I compactifications in four dimensions
We discuss type I-heterotic duality in four-dimensional models obtained as a Coulomb phase of the six-dimensional U(16) orientifold model compactified on T2 with arbitrary SU(16) Wilson lines. We show that Kahler potentials, gauge threshold corrections and the infinite tower of higher derivative F-terms agree in the limit that corresponds to weak coupling, large T2 heterotic compactifications. On the type I side, all these quantities are completely determined by the spectrum of N = 2 BPS states that originate from D = 6 massless superstring modes.
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.
119276770
Maximally Helicity Violating Disk Amplitudes, Twistors and Transcendental Integrals
Abstract We obtain simple expressions for tree-level maximally helicity violating amplitudes of N gauge bosons from disk world-sheets of open superstrings. The amplitudes are written in terms of ( N − 3 ) ! hypergeometric integrals depending on kinematic parameters, weighted by certain kinematic factors. The integrals are transcendental in a strict sense defined in this work. The respective kinematic factors can be succinctly written in terms of “dual” momentum-twistors. The amplitudes are computed by using the prescription proposed by Berkovits and Maldacena.
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.
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.
115450618
A final focus design for the CERN linear collider CLIC
121851945
Design, test and performance of the prototype superconducting quadrupole for the LEP low-beta insertions
The prototype of the superconducting quadrupoles for the low-beta insertions at the Large Electron-Positron collider has been tested successfully. This industry-built quadrupole, which has a warm bore of 130 mm and a magnetic length of 2 m, is required to provide a gradient of 36 T/m over a field aperture of 1000 mm diameter. It achieved its maximum operating current without training. While retaining the main characteristics of its ISR predecessors, the design of this magnet incorporates several novel features, due to constraints imposed by the environment of the LEP experiments. In particular the quadrupole is slender and ironless, and has a horizontally oriented cryogenic service funnel. Following a description of the major aspects of the design, the results are given of the magnetic and cryogenic tests and measurements. >
54553106
Quench performance and field quality measurements of the first LHC low-/spl beta/ quadrupole model
As part of the LHC magnet development program, CERN in collaboration with Oxford Instruments has designed, built and tested a one metre model of a 70 mm aperture low-/spl beta/ quadrupole. The magnet features a four layer coil, and is designed for 250 T/m at 1.9 K. We review the results of the magnet training and quench propagation studies performed at 4.3 K and 1.9 K, and report on the magnetic field measurements.
115978348
Tau-charm factory cost estimate
118159983
The LHC:: a new hadron collider for experimental physics
Abstract The Large Hadron Collider is now under construction at CERN. This accelerator will be by far the most powerful ever built, and will provide the current generation of experimental physicists with an extraordinary opportunity to make new discoveries. It will also provide accelerator scientists with a tool to test current theory and refine studies of possible future accelerators going to even higher energies. The environment of a collider is such that experts of both disciplines have to collaborate closely, and this will surely continue to be to the long-term advantage of our whole field of science.