302 research outputs found
Recommended from our members
Geometry description markup language for physics simulation and analysis applications
The Geometry Description Markup Language (GDML) is a specialized XML-based language designed as an application-independent persistent format for describing the geometries of detectors associated with physics measurements. It serves to implement ''geometry trees'' which correspond to the hierarchy of volumes a detector geometry can be composed of, and to allow to identify the position of individual solids, as well as to describe the materials they are made of. Being pure XML, GDML can be universally used, and in particular it can be considered as the format for interchanging geometries among different applications. In this paper we will present the current status of the development of GDML. After having discussed the contents of the latest GDML schema, which is the basic definition of the format, we will concentrate on the GDML processors. We will present the latest implementation of the GDML ''writers'' as well as ''readers'' for either Geant4 [2], [3] or ROOT [4], [10]
The W_L W_L scattering at the LHC: improving the selection criteria
We present a systematic study of the different mechanisms leading to WW pair
production at the LHC, both in the same-sign and opposite-sign channels, and we
emphasize that the former offers much better potential for investigating
non-resonant W_L W_L scattering. We propose a new kinematic variable to isolate
the W_L W_L scattering component in same-sign WW production at the LHC.
Focusing on purely leptonic W decay channels, we show that it considerably
improves the LHC capabilities to shed light on the electroweak symmetry
breaking mechanism after collecting 100 fb^{-1} of data at sqrt{s} = 14 TeV.
The new variable is less effective in the opposite-sign WW channel due to
different background composition.Comment: 25 pages, 32 figure
Generalized Two-Dimensional QCD
We study two-dimensional gauge theories with fundamental fermions and a
general first order gauge-field Lagrangian. For the case of U(1) we show how
standard bosonization of the Schwinger model generalizes to give mesons
interacting through a general Landau-Ginzburg potential. We then show how for a
subclass of SU(N) theories, 't Hooft's solution of large N two-dimensional QCD
can be generalized in a consistent and natural manner. We finally point out the
possible relevance of studying these theories to the string formulation of
two-dimensional QCD as well as to understanding QCD in higher dimensions.Comment: LPTENS-94/2, IASSNS-HEP-94/3, and RU-94-8. (harvmac with 4 figures,
23 pp.
Gauge Invariant Cutoff QED
A hidden generalized gauge symmetry of a cutoff QED is used to show the
renormalizability of QED. In particular, it is shown that corresponding Ward
identities are valid all along the renormalization group flow. The exact
Renormalization Group flow equation corresponding to the effective action of a
cutoff lambda phi^4 theory is also derived. Generalization to any gauge group
is indicated.Comment: V1: 18 pages, 2 figures; V2: Discussions improved. Version accepted
for publication in Physica Script
Update on Fermion Mass Models with an Anomalous Horizontal U(1) Symmetry
We reconsider models of fermion masses and mixings based on a gauge anomalous
horizontal U(1) symmetry. In the simplest model with a single flavon field and
horizontal charges of the same sign for all Standard Model fields, only very
few charge assignements are allowed when all experimental data, including
neutrino oscillation data, is taken into account. We show that a precise
description of the observed fermion masses and mixing angles can easily be
obtained by generating sets of the order one parameters left unconstrained by
the U(1) symmetry. The corresponding Yukawa matrices show several interesting
features which may be important for flavour changing neutral currents and CP
violation effects in supersymmetric models.Comment: 23 pages, 8 figure
Neutrinos, Axions and Conformal Symmetry
We demonstrate that radiative breaking of conformal symmetry (and
simultaneously electroweak symmetry) in the Standard Model with right-chiral
neutrinos and a minimally enlarged scalar sector induces spontaneous breaking
of lepton number symmetry, which naturally gives rise to an axion-like particle
with some unusual features. The couplings of this `axion' to Standard Model
particles, in particular photons and gluons, are entirely determined (and
computable) via the conformal anomaly, and their smallness turns out to be
directly related to the smallness of the masses of light neutrinos.Comment: 10 pages, 2 figures, expanded version, to be published in EPJ
Merging gauge coupling constants without Grand Unification
The merging of the running couplings constants of the weak, strong, and
electromagnetic fields does not require the unification of these gauge fields
at high energy. It can, in fact, be the property of a general fermionic system
in which gauge bosons are not fundamental.Comment: 11 pages, 1 figure, v3: to appear in JETP Letter
The Price of WMAP Inflation in Supergravity
The three-year data from WMAP are in stunning agreement with the simplest
possible quadratic potential for chaotic inflation, as well as with new or
symmetry-breaking inflation. We investigate the possibilities for incorporating
these potentials within supergravity, particularly of the no-scale type that is
motivated by string theory. Models with inflation driven by the matter sector
may be constructed in no-scale supergravity, if the moduli are assumed to be
stabilised by some higher-scale dynamics and at the expense of some
fine-tuning. We discuss specific scenarios for stabilising the moduli via
either D- or F-terms in the effective potential, and survey possible
inflationary models in the presence of D-term stabilisation.Comment: 15 pages, 6 figures, plain Late
Tools for Deconstructing Gauge Theories in AdS5
We employ analytical methods to study deconstruction of 5D gauge theories in
the AdS5 background. We demonstrate that using the so-called q-Bessel functions
allows a quantitative analysis of the deconstructed setup. Our study clarifies
the relation of deconstruction with 5D warped theories.Comment: 30 pages; v2: several refinements, references adde
- …