9,845 research outputs found
Direct Searches of New Physics at CLIC
The multi-TeV e+e- collider CLIC may allow for the direct study of new
neutral gauge bosons or Kaluza-Klein states in the TeV range. We discuss some
of the experimental aspects for the study of such resonances. Further we
discuss briefly the effects of soft branes in scenarios with Large Extra
Dimensions, and the production of Black Holes at CLIC.Comment: 9 pages, 4 figures, to appear in the proceedings of the LCWS02
Worksho
Graviton Production at CLIC
Direct production of Kaluza-Klein states in the TeV range is studied for the
experimental environment at the multi-TeV collider CLIC. The
sensitivity of such data to model parameters is discussed for the
Randall-Sundrum(RS) and TeV scale extra dimensional models.Comment: 5 pages, 5 figures, to appear on the Proceedings of the Snowmass 2001
Summer Study, Snowmass CO (USA), July 200
Multi-Higgs boson production in the Standard Model and beyond
We present a calculation of the loop-induced processes gg -> HH and gg ->
HHH, and investigate the observability of multi-Higgs boson production at the
CERN Large Hadron Collider (LHC) in the Standard Model (SM) and beyond. While
the SM cross sections are too small to allow observation at the LHC, we
demonstrate that physics beyond the SM can lead to amplified, observable cross
sections. Furthermore, the applicability of the heavy top quark approximation
in two- and three-Higgs boson production is investigated. We conclude that
multi-Higgs boson production at the SuperLHC is an interesting probe of Higgs
sectors beyond the SM and warrants further study.Comment: 17 pages, 17 figure
Convex Polytopes and Quasilattices from the Symplectic Viewpoint
We construct, for each convex polytope, possibly nonrational and nonsimple, a
family of compact spaces that are stratified by quasifolds, i.e. each of these
spaces is a collection of quasifolds glued together in an suitable way. A
quasifold is a space locally modelled on modulo the action of a
discrete, possibly infinite, group. The way strata are glued to each other also
involves the action of an (infinite) discrete group. Each stratified space is
endowed with a symplectic structure and a moment mapping having the property
that its image gives the original polytope back. These spaces may be viewed as
a natural generalization of symplectic toric varieties to the nonrational
setting.Comment: LaTeX, 29 pages. Revised version: TITLE changed, reorganization of
notations and exposition, added remarks and reference
Testing the Higgs Mechanism in the Lepton Sector with multi-TeV e+e- Collisions
Multi-TeV e+e- collisions provide with a large enough sample of Higgs bosons
to enable measurements of its suppressed decays. Results of a detailed study of
the determination of the muon Yukawa coupling at 3 TeV, based on full detector
simulation and event reconstruction, are presented. The muon Yukawa coupling
can be determined with a relative accuracy of 0.04 to 0.08 for Higgs bosons
masses from 120 GeV to 150 GeV, with an integrated luminosity of 5 inverse-ab.
The result is not affected by overlapping two-photon background.Comment: 6 pages, 2 figures, submitted to J Phys G.: Nucl. Phy
Contrasting Supersymmetry and Universal Extra Dimensions at Colliders
We contrast the experimental signatures of low energy supersymmetry and the
model of Universal Extra Dimensions and discuss various methods for their
discrimination at hadron and lepton colliders. We study the discovery reach of
hadron colliders for level 2 Kaluza-Klein modes, which would indicate the
presence of extra dimensions. We also investigate the possibility to
differentiate the spins of the superpartners and KK modes by means of the
asymmetry method of Barr. We then review the methods for discriminating between
the two scenarios at a high energy linear collider such as CLIC. We consider
the processes of Kaluza-Klein muon pair production in universal extra
dimensions in parallel to smuon pair production in supersymmetry. We find that
the angular distributions of the final state muons, the energy spectrum of the
radiative return photon and the total cross-section measurement are powerful
discriminators between the two models.Comment: 6 pages, 8 figures, to appear in the proceedings of the 2005
International Linear Collider Workshop, Stanford, US
Constraints on Sterile Neutrino Dark Matter
We present a comprehensive analysis of constraints on the sterile neutrino as
a dark matter candidate. The minimal production scenario with a standard
thermal history and negligible cosmological lepton number is in conflict with
conservative radiative decay constraints from the cosmic X-ray background in
combination with stringent small-scale structure limits from the Lyman-alpha
forest. We show that entropy release through massive particle decay after
production does not alleviate these constraints. We further show that radiative
decay constraints from local group dwarf galaxies are subject to large
uncertainties in the dark matter density profile of these systems. Within the
strongest set of constraints, resonant production of cold sterile neutrino dark
matter in non-zero lepton number cosmologies remains allowed.Comment: 9 pages, 3 figures; v2 includes discussion of astro-ph/0605706 and
matches version to appear in Phys. Rev.
Tensors: a guide for undergraduate students
A guide on tensors is proposed for undergraduate students in physics or engineering that ties
directly to vector calculus in orthonormal coordinate systems. We show that once orthonormality is
relaxed, a dual basis, together with the contravariant and covariant components, naturally emerges.
Manipulating these components requires some skill that can be acquired more easily and quickly
once a new notation is adopted. This notation distinguishes multi-component quantities in different
coordinate systems by a differentiating sign on the index labelling the component rather than on the
label of the quantity itself. This tiny stratagem, together with simple rules openly stated at the
beginning of this guide, allows an almost automatic, easy-to-pursue procedure for what is
otherwise a cumbersome algebra. By the end of the paper, the reader will be skillful enough to
tackle many applications involving tensors of any rank in any coordinate system, without indexmanipulation
obstacles standing in the way
The Symplectic Penrose Kite
The purpose of this article is to view the Penrose kite from the perspective
of symplectic geometry.Comment: 24 pages, 7 figures, minor changes in last version, to appear in
Comm. Math. Phys
Contrasting Supersymmetry and Universal Extra Dimensions at the CLIC Multi-TeV e+e- Collider
Universal extra dimensions and supersymmetry have rather similar experimental
signatures at hadron colliders. The proper interpretation of an LHC discovery
in either case may therefore require further data from a lepton collider. In
this paper we identify methods for discriminating between the two scenarios at
the linear collider. We study the processes of Kaluza-Klein muon pair
production in universal extra dimensions in parallel to smuon pair production
in supersymmetry, accounting for the effects of detector resolution, beam-beam
interactions and accelerator induced backgrounds. We find that the angular
distributions of the final state muons, the energy spectrum of the radiative
return photon and the total cross-section measurement are powerful
discriminators between the two models. Accurate determination of the particle
masses can be obtained both by a study of the momentum spectrum of the final
state leptons and by a scan of the particle pair production thresholds. We also
calculate the production rates of various Kaluza-Klein particles and discuss
the associated signatures.Comment: 20 pages, 13 figures, typeset in JHEP style, uses axodraw. Added new
section 5. Version to appear in JHE
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