10,525 research outputs found
Partially composite 2-Higgs-doublet model
In the extra dimensional scenarios with gauge fields in the bulk, the
Kaluza-Klein (KK) gauge bosons can induce Nambu-Jona-Lasinio (NJL) type
attractive four-fermion interactions, which can break electroweak symmetry
dynamically with accompanying composite Higgs fields. We consider a possibility
that electroweak symmetry breaking (EWSB) is triggered by both a fundamental
Higgs and a composite Higgs arising in a dynamical symmetry breaking mechanism
induced by a new strong dynamics. The resulting Higgs sector is a partially
composite two-Higgs doublet model with specific boundary conditions on the
coupling and mass parameters originating at a compositeness scale .
The phenomenology of this model is discussed including the collider
phenomenology at LHC and ILC.Comment: To appear in the proceeding of LCWS06, Bangalore, Indi
Improving the sensitivity of stop searches with on-shell constrained invariant mass variables
The search for light stops is of paramount importance, both in general as a
promising path to the discovery of beyond the standard model physics and more
specifically as a way of evaluating the success of the naturalness paradigm.
While the LHC experiments have ruled out much of the relevant parameter space,
there are "stop gaps", i.e., values of sparticle masses for which existing LHC
analyses have relatively little sensitivity to light stops. We point out that
techniques involving on-shell constrained M_2 variables can do much to enhance
sensitivity in this region and hence help close the stop gaps. We demonstrate
the use of these variables for several benchmark points and describe the effect
of realistic complications, such as detector effects and combinatorial
backgrounds, in order to provide a useful toolkit for light stop searches in
particular, and new physics searches at the LHC in general.Comment: 49 pages, 28 figures, revised version published in JHEP, references
adde
On-shell constrained variables with applications to mass measurements and topology disambiguation
We consider a class of on-shell constrained mass variables that are 3+1
dimensional generalizations of the Cambridge variable and that
automatically incorporate various assumptions about the underlying event
topology. The presence of additional on-shell constraints causes their
kinematic distributions to exhibit sharper endpoints than the usual
distribution. We study the mathematical properties of these new variables,
e.g., the uniqueness of the solution selected by the minimization over the
invisible particle 4-momenta. We then use this solution to reconstruct the
masses of various particles along the decay chain. We propose several tests for
validating the assumed event topology in missing energy events from new
physics. The tests are able to determine: 1) whether the decays in the event
are two-body or three-body, 2) if the decay is two-body, whether the
intermediate resonances in the two decay chains are the same, and 3) the exact
sequence in which the visible particles are emitted from each decay chain.Comment: 44pages, 17 figures. revised version, published in JHEP. Minor
addition: a paragraph discussing the effect on the background at the end of
section 5.
Exactly Soluble Quantum Wormhole in Two Dimensions
We are presenting a quantum traversable wormhole in an exactly soluble
two-dimensional model. This is different from previous works since the exotic
negative energy that supports the wormhole is generated from the quantization
of classical energy-momentum tensors. This explicit illustration shows the
quantum-mechanical energy can be used as a candidate for the exotic source. As
for the traversability, after a particle travels through the wormhole, the
static initial wormhole geometry gets a back reaction which spoils the wormhole
structure. However, it may still maintain the initial structure along with the
appropriate boundary condition.Comment: v1. 13 pages, 1 figure, REVTeX3; v2. 1 Ref. added, REVTeX4, to appear
in Phys. Rev.
OPTIMASS: A Package for the Minimization of Kinematic Mass Functions with Constraints
Reconstructed mass variables, such as , , , and
, play an essential role in searches for new physics at hadron
colliders. The calculation of these variables generally involves constrained
minimization in a large parameter space, which is numerically challenging. We
provide a C++ code, OPTIMASS, which interfaces with the MINUIT library to
perform this constrained minimization using the Augmented Lagrangian Method.
The code can be applied to arbitrarily general event topologies and thus allows
the user to significantly extend the existing set of kinematic variables. We
describe this code and its physics motivation, and demonstrate its use in the
analysis of the fully leptonic decay of pair-produced top quarks using the
variables.Comment: 39 pages, 12 figures, (1) minor revision in section 3, (2) figure
added in section 4.3, (3) reference added and (4) matched with published
versio
Exact solutions of charged wormhole
In this paper, the backreaction to the traversable Lorentzian wormhole
spacetime by the scalar field or electric charge is considered to find the
exact solutions. The charges play the role of the additional matter to the
static wormhole which is already constructed by the exotic matter. The
stability conditions for the wormhole with scalar field and electric charge are
found from the positiveness and flareness for the wormhole shape function.Comment: 9 pages, Revtex, no figures, to appear in Phys. Rev. D(2001
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