27,458 research outputs found
Physics at TESLA
The physics at a 500-800 GeV electron positron linear collider, TESLA, is
reviewed. The machine parameters that impact directly on the physics are
discussed and a few key performance goals for a detector at TESLA are given.
Emphasis is placed on precision measurements in the Higgs and top sectors and
on extrapolation to high energy scales in the supersymmetric scenario.Comment: Talk presented at Lake Louise Winter Institute 2001. 7 pages, 2
figure
Non-commutativity and non-associativity of the doubled string in non-geometric backgrounds
We use a T-duality invariant action to investigate the behaviour of a string
in non-geometric backgrounds, where there is a non-trivial global
patching or monodromy. This action leads to a set of Dirac brackets describing
the dynamics of the doubled string, with these brackets determined only by the
monodromy. This allows for a simple derivation of non-commutativity and
non-associativity in backgrounds which are (even locally) non-geometric. We
focus here on the example of the three-torus with H-flux, finding
non-commutativity but not non-associativity, and also comment on the relation
to the exotic brane, which shares the same monodromy.Comment: 31 pages, v2: refs added, corrections to sec 5, results updated, v3:
published version with additional discussion in sec
Conserved Currents of Double Field Theory
We find the conserved current associated to invariance under generalised
diffeomorphisms in double field theory. This can be used to define a
generalised Komar integral. We comment on its applications to solutions, in
particular to the fundamental string/pp-wave. We also discuss the current in
the context of Scherk-Schwarz compactifications. We calculate the current for
both the original double field theory action, corresponding to the NSNS sector
alone, and for the RR sector.Comment: 30 pages + appendix, v2: belated update to match published version
(typos + refs fixed, some minor comments added
Measuring Gauge-Mediated SuperSymmetry Breaking Parameters at a 500 GeV e+e- Linear Collider
We consider the phenomenology of a class of gauge-mediated supersymmetry
(SUSY) breaking (GMSB) models at a e+e- Linear Collider (LC) with c.o.m. energy
up to 500 GeV. In particular, we refer to a high-luminosity (L ~ 3 x 10^34
cm^-2 s^-1) machine, and use detailed simulation tools for a proposed detector.
Among the GMSB-model building options, we define a simple framework and outline
its predictions at the LC, under the assumption that no SUSY signal is detected
at LEP or Tevatron. Our focus is on the case where a neutralino (N1) is the
next-to-lightest SUSY particle (NLSP), for which we determine the relevant
regions of the GMSB parameter space. Many observables are calculated and
discussed, including production cross sections, NLSP decay widths, branching
ratios and distributions, for dominant and rare channels. We sketch how to
extract the messenger and electroweak scale model parameters from a spectrum
measured via, e.g. threshold-scanning techniques. Several experimental methods
to measure the NLSP mass and lifetime are proposed and simulated in detail. We
show that these methods can cover most of the lifetime range allowed by
perturbativity requirements and suggested by cosmology in GMSB models. Also,
they are relevant for any general low-energy SUSY breaking scenario. Values of
c*tau_N1 as short as 10's of microns and as long as 10's of metres can be
measured with errors at the level of 10% or better after one year of LC running
with high luminosity. We discuss how to determine a narrow range (<~ 5%) for
the fundamental SUSY breaking scale sqrt(F), based on the measured m_N1,
c*tau_N1. Finally, we suggest how to optimise the LC detector performance for
this purpose.Comment: 56 pages, 32 figures (48 eps files), LaTeX + epsf.sty + colordvi.sty.
Revision v2: minor changes/additions, version to be published in EPJ
Precision GMSB at a Linear Collider
We simulate precision measurements of gauge-mediated supersymmetry breaking
(GMSB) parameters at a 500 GeV e+e- linear collider in the scenario where a
neutralino is the next-to-lightest supersymmetric particle. Information on the
supersymmetry breaking and the messenger sectors of the theory is extracted
from the measured sparticle mass spectrum and neutralino lifetime.Comment: LaTeX + sprocl.sty + epsf.sty, 6 pages, 3 figures (5 eps files
Extracting GMSB Parameters at a Linear Collider
Assuming gauge-mediated supersymmetry breaking, we simulate precision
measurements of fundamental parameters at a 500 GeV e+e- linear collider in the
scenario where a neutralino is the next-to-lightest supersymmetric particle.
Information on the supersymmetry breaking and the messenger sectors of the
theory is extracted from realistic fits to the measured mass spectrum of the
Minimal Supersymmetric Model particles and the next-to-lightest supersymmetric
particle lifetime.Comment: 6 pages, LaTeX + epsf.sty, 3 figure
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