5,424 research outputs found
Production of Z' and W' via Drell-Yan processes in the 4D Composite Higgs Model at the LHC
We present an analysis of both the Neutral Current (NC) and Charged Current
(CC) Drell-Yan processes at the LHC within a 4 Dimensional realization of a
Composite Higgs model studying the cross sections and taking into account the
possible impact of the extra fermions present in the spectrum.Comment: Conference proceeding, XII IFAE Edition, 3-5 April 2013, Cagliari. 2
pages, 2 figures; v2 typo correcte
Higgs Boson in the 4DCHM: LHC phenomenology
Composite Higgs models provide an elegant solution to the hierarchy problem
present in the Standard Model (SM) and give an alternative pattern leading to
the mechanism of Electro-Weak Symmetry Breaking (EWSB). We present an analysis
of the Higgs boson production and decay within a recently proposed realistic
realization of this general idea: the 4D Composite Higgs Model (4DCHM).
Comparing our results with the latest Large Hadron Collider (LHC) data we show
that the 4DCHM could provide an alternative explanation with respect to the SM
of the LHC results pointing to the discovery of a Higgs-like particle at 125
GeV.Comment: Conference proceeding, EPS-HEP 2013, 18-24 July 2013, Stockholm. 3
pages, 2 figures, typo correcte
Framework for Model Independent Analyses of Multiple Extra Quark Scenarios
In this paper we present an analysis strategy and a dedicated tool to
determine the exclusion confidence level for any scenario involving multiple
heavy extra quarks with generic decay channels, as predicted in several
extensions of the Standard Model. We have created, validated and used a
software package, called XQCAT (eXtra Quark Combined Analysis Tool), which is
based on publicly available experimental data from direct searches for top
partners and from Supersymmetry inspired searches. By means of this code, we
recast the limits from CMS on new heavy extra quarks considering a complete set
of decay channels. The resulting exclusion confidence levels are presented for
some simple scenarios with multiple states and general coupling assumptions.
Highlighting the importance of combining multiple topology searches to obtain
accurate re-interpretations of the existing searches, we discuss the reach of
the SUSY analyses so as to set bounds on new quark resonances. In particular,
we report on the re-interpretation of the existing limits on benchmark
scenarios with one and multiple pair-produced top partners having non-exclusive
couplings to the third Standard Model generation of quarks.Comment: 31 pages, 6 figures, 3 tables, version accepted for publication in
JHE
The Relationship Between Stellar Light Distributions of Galaxies and their Formation Histories
A major problem in extragalactic astronomy is the inability to distinguish in
a robust, physical, and model independent way how galaxy populations are
related to each other and to their formation histories. A similar, but
distinct, and also long standing question is whether the structural appearances
of galaxies, as seen through their stellar light distributions, contain enough
physical information to offer this classification. We argue through the use of
240 images of nearby galaxies that three model independent parameters measured
on a single galaxy image reveal its major ongoing and past formation modes, and
can be used as a robust classification system. These parameters quantitatively
measure: the concentration (C), asymmetry (A) and clumpiness (S) of a galaxy's
stellar light distribution. When combined into a three dimensional `CAS' volume
all major classes of galaxies in various phases of evolution are cleanly
distinguished. We argue that these three parameters correlate with important
modes of galaxy evolution: star formation and major merging activity. This is
argued through the strong correlation of Halpha equivalent width and broad band
colors with the clumpiness parameter, the uniquely large asymmetries of 66
galaxies undergoing mergers, and the correlation of bulge to total light
ratios, and stellar masses, with the concentration index. As an obvious goal is
to use this system at high redshifts to trace evolution, we demonstrate that
these parameters can be measured, within a reasonable and quantifiable
uncertainty, with available data out to z ~ 3 using the Hubble Space Telescope
GOODS ACS and Hubble Deep Field images.Comment: ApJS, in press, 30 pages, Figures 15 and 16 are in color. For a full
resolution version, please go to http://www.astro.caltech.edu/~cc/cas.p
Johnson-Kendall-Roberts theory applied to living cells
Johnson-Kendall-Roberts (JKR) theory is an accurate model for strong adhesion
energies of soft slightly deformable material. Little is known about the
validity of this theory on complex systems such as living cells. We have
addressed this problem using a depletion controlled cell adhesion and measured
the force necessary to separate the cells with a micropipette technique. We
show that the cytoskeleton can provide the cells with a 3D structure that is
sufficiently elastic and has a sufficiently low deformability for JKR theory to
be valid. When the cytoskeleton is disrupted, JKR theory is no longer
applicable
A 4D Composite Higgs Model: Testing its Scalar Sector at the LHC
We explain the current Large Hadron Collider (LHC) data pointing to the
discovery of a neutral Higgs boson in the context of a 4-Dimensional Composite
Higgs Model (4DCHM). The full particle spectrum of this scenario is derived
without any approximation and implemented in automated computational tools to
enable fast phenomenological investigation. Several parameter configurations
compliant with experimental constraints are presented and discussed. A
fit to the LHC data quantifying the consistency of the 4DCHM as a whole with
experimental evidence is finally performed.Comment: 10 pages, 6 figures, 2 tables, talk given at the `International
Workshop on Higgs as a Probe of New Physics 2013', 13-16 February 2013,
Toyama, Japa
Composite Higgs searches at the LHC and beyond
General Composite Higgs models provide an elegant solution to the hierarchy problem present in the Standard Model and give an alternative pattern leading to the mechanism of electroweak (EW) symmetry breaking. We present an analysis of a realistic realization of this general idea, namely the 4DCHM, analysing the Higgs production and decay modes, fitting them to the latest LHC showing the compatibility with the results of the CERN machine. We then present the prospects of a future electron positron collider of testing this model against the expected experimental accuracies in the various Higgs decay channels accessible herein
New vector bosons in the electroweak sector: a renormalizable model with decoupling
A linear realization of a model of dynamical electroweak symmetry breaking
describing additional heavy vector bosons is proposed. The model is a SU(2)_L x
U(1) x SU(2)_L' x SU(2)_R' gauge theory, breaking at some high scale u to
SU(2)_weak x U(1)_Y and breaking again in the standard way at the electroweak
scale v to U(1)_(em). The model is renormalizable and reproduces the Standard
Model in the limit u\to infinity. This decoupling property is shown to hold
also at the level of radiative corrections by computing, in particular, the
epsilon parameters.Comment: 39 pages, 16 Figures, Late
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