14 research outputs found
The LHC Inverse Problem, Supersymmetry and the ILC
We address the question whether the ILC can resolve the LHC Inverse Problem within the framework of the MSSM. We examine 242 points in the MSSM parameter space which were generated at random and were found to give indistinguishable signatures at the LHC. After a realistic simulation including full Standard Model backgrounds and a fast detector simulation, we find that roughly only one third of these scenarios lead to visible signatures of some kind with a significance {ge} 5 at the ILC with {radical}s = 500 GeV. Furthermore, we examine these points in parameter space pairwise and find that only one third of the pairs are distinguishable at the ILC at 5{sigma}
Higgsless Electroweak Symmetry Breaking in Warped Backgrounds: Constraints and Signatures
We examine the phenomenology of a warped 5-dimensional model based on
SU(2) SU(2) U(1) model which implements
electroweak symmetry breaking through boundary conditions, without the presence
of a Higgs boson. We use precision electroweak data to constrain the general
parameter space of this model. Our analysis includes independent and
gauge couplings, radiatively induced UV boundary gauge kinetic terms, and all
higher order corrections from the curvature of the 5-d space. We show that this
setup can be brought into good agreement with the precision electroweak data
for typical values of the parameters. However, we find that the entire range of
model parameters leads to violation of perturbative unitarity in gauge boson
scattering and hence this model is not a reliable perturbative framework.
Assuming that unitarity can be restored in a modified version of this scenario,
we consider the collider signatures. It is found that new spin-1 states will be
observed at the LHC and measurement of their properties would identify this
model. However, the spin-2 graviton Kaluza-Klein resonances, which are a
hallmark of the Randall-Sundrum model, are too weakly coupled to be detected.Comment: More detailed analysis, added references, 43 pages, 15 figures, LaTe
TeV Mini Black Hole Decay at Future Colliders
It is generally believed that mini black holes decay by emitting elementary
particles with a black body energy spectrum. The original calculation lead to
the conclusion that about the 90% of the black hole mass is radiated away in
the form of photons, neutrinos and light leptons, mainly electrons and muons.
With the advent of String Theory, such a scenario must be updated by including
new effects coming from the stringy nature of particles and interactions.By
taking for granted that black holes can be produced in hadronic collisions,
then their decay must take into account that: (i) we live in a D3-Brane
embedded into an higher dimensional bulk spacetime; (ii) fundamental
interactions, including gravity, are unified at TeV energy scale. Thus, the
formal description of the Hawking radiation mechanism has to be extended to the
case of more than four spacetime dimensions and include the presence of
D-branes. Furthermore, unification of fundamental interactions at an energy
scale many order of magnitude lower than the Planck energy implies that any
kind of fundamental particle, not only leptons, is expected to be emitted. A
detailed understanding of the new scenario is instrumental for optimal tuning
of detectors at future colliders, where, hopefully, this exciting new physics
will be tested. In this article we review higher dimensional black hole decay,
considering not only the emission of particles according to Hawking mechanism,
but also their near horizon QED/QCD interactions. The ultimate motivation is to
build up a phenomenologically reliable scenario, allowing a clear experimental
signature of the event.Comment: 22 pages, 9 figures, 4 tables; ``quick review'' for Class. and
Quantum Gra
The Discovery Potential of a Super B Factory
The Proceedings of the 2003 SLAC Workshops on flavor physics with a high
luminosity asymmetric e+e- collider. The sensitivity of flavor physics to
physics beyond the Standard Model is addressed in detail, in the context of the
improvement of experimental measurements and theoretical calculations.Comment: 476 pages. Printed copies may be obtained by request to
[email protected] . arXiv admin note: v2 appears to be identical to v
Shedding Light on the Dark Sector with Direct WIMP Production
A Weakly Interacting Massive Particle (WIMP) provides an attractive dark
matter candidate, and should be within reach of the next generation of
high-energy colliders. We consider the process of direct WIMP pair-production,
accompanied by an initial-state radiation photon, in electron-positron
collisions at the proposed International Linear Collider (ILC). We present a
parametrization of the differential cross section for this process which
conveniently separates the model-independent information provided by cosmology
from the model-dependent inputs from particle physics. As an application, we
consider two simple models, one supersymmetric, and another of the "universal
extra dimensions" (UED) type. The discovery reach of the ILC and the expected
precision of parameter measurements are studied in each model. In addition, for
each of the two examples, we also investigate the ability of the ILC to
distinguish between the two models through a shape-discrimination analysis of
the photon energy spectrum. We show that with sufficient beam polarization the
alternative model interpretation can be ruled out in a large part of the
relevant parameter space.Comment: 21 pages, 9 figure
Simplified Models for LHC New Physics Searches
This document proposes a collection of simplified models relevant to the
design of new-physics searches at the LHC and the characterization of their
results. Both ATLAS and CMS have already presented some results in terms of
simplified models, and we encourage them to continue and expand this effort,
which supplements both signature-based results and benchmark model
interpretations. A simplified model is defined by an effective Lagrangian
describing the interactions of a small number of new particles. Simplified
models can equally well be described by a small number of masses and
cross-sections. These parameters are directly related to collider physics
observables, making simplified models a particularly effective framework for
evaluating searches and a useful starting point for characterizing positive
signals of new physics. This document serves as an official summary of the
results from the "Topologies for Early LHC Searches" workshop, held at SLAC in
September of 2010, the purpose of which was to develop a set of representative
models that can be used to cover all relevant phase space in experimental
searches. Particular emphasis is placed on searches relevant for the first
~50-500 pb-1 of data and those motivated by supersymmetric models. This note
largely summarizes material posted at http://lhcnewphysics.org/, which includes
simplified model definitions, Monte Carlo material, and supporting contacts
within the theory community. We also comment on future developments that may be
useful as more data is gathered and analyzed by the experiments.Comment: 40 pages, 2 figures. This document is the official summary of results
from "Topologies for Early LHC Searches" workshop (SLAC, September 2010).
Supplementary material can be found at http://lhcnewphysics.or
CP Studies and Non-Standard Higgs Physics
There are many possibilities for new physics beyond the Standard Model that
feature non-standard Higgs sectors. These may introduce new sources of CP
violation, and there may be mixing between multiple Higgs bosons or other new
scalar bosons. Alternatively, the Higgs may be a composite state, or there may
even be no Higgs at all. These non-standard Higgs scenarios have important
implications for collider physics as well as for cosmology, and understanding
their phenomenology is essential for a full comprehension of electroweak
symmetry breaking. This report discusses the most relevant theories which go
beyond the Standard Model and its minimal, CP-conserving supersymmetric
extension: two-Higgs-doublet models and minimal supersymmetric models with CP
violation, supersymmetric models with an extra singlet, models with extra gauge
groups or Higgs triplets, Little Higgs models, models in extra dimensions, and
models with technicolour or other new strong dynamics. For each of these
scenarios, this report presents an introduction to the phenomenology, followed
by contributions on more detailed theoretical aspects and studies of possible
experimental signatures at the LHC and other colliders.Comment: Report of the CPNSH workshop, May 2004 - Dec 2005, 542 pages. The
complete report as well as its individual chapters are also available from
http://kraml.home.cern.ch/kraml/cpnsh/report.htm