25 research outputs found
Use of transverse beam polarization to probe anomalous VVH interactions at a Linear Collider
We investigate use of transverse beam polarization in probing anomalous
coupling of a Higgs boson to a pair of vector bosons, at the International
Linear Collider (ILC). We consider the most general form of VVH (V = W/Z)
vertex consistent with Lorentz invariance and investigate its effects on the
process e+ e- --> f bar{f} H, f being a light fermion. Constructing observables
with definite CP and naive time reversal (tilde T) transformation properties,
we find that transverse beam polarization helps us to improve on the
sensitivity of one part of the anomalous ZZH coupling that is odd under CP.
Even more importantly it provides the possibility of discriminating from each
other, two terms in the general ZZH vertex, both of which are even under CP and
tilde T. Use of transverse beam polarization when combined with information
from unpolarized and linearly polarized beams therefore, allows one to have
completely independent probes of all the different parts of a general ZZH
vertex.Comment: 15 pages, 3 figures, published versio
Anomalous Triple Gauge Vertices at the Large Hadron-Electron Collider
At a high energy collider, such as the Large Hadron-Electron Collider
(LHeC) which is being planned at CERN, one can access the vertex
exclusively in charged current events with a radiated photon, with no
interference from the vertex. We find that the azimuthal angle between
the jet and the missing momentum in each charged current event is a sensitive
probe of anomalous couplings, and show that for quite reasonable
values of integrated luminosity, the LHeC can extend the discovery reach for
these couplings beyond all present experimental bounds.Comment: 11 pages, LaTeX2e, 5 EPS figure
Effects of polarisation on study of anomalous VVH interactions at a Linear Collider
We investigate the use of beam polarisation as well as final state
polarisation effects in probing the interaction of the Higgs boson with a pair
of heavy vector bosons in the process , where is
any light fermion. The sensitivity of the International Linear Collider (ILC)
operating at GeV, to such () couplings is examined
in a model independent way. The effects of ISR and beamstrahlung are discussed.Comment: To appear in the proceedings of 2007 International Linear Collider
Workshop (LCWS07 and ILC07), Hamburg, Germany, 30 May - 3 Jun 2007. 4 pages,
LaTeX, 1 eps figure. requires ilcws07.cls. included in submissio
Signatures of anomalous VVH interactions at a linear collider
We examine, in a model independent way, the sensitivity of a Linear Collider
to the couplings of a light Higgs boson to gauge bosons. Including the
possibility of CP violation, we construct several observables that probe the
different anomalous couplings possible. For an intermediate mass Higgs, a
collider operating at a center of mass energy of 500 GeV and with an integrated
luminosity of 500 fb is shown to be able to constrain the vertex
at the few per cent level, and with even higher sensitivity in certain
directions. However, the lack of sufficient number of observables as well as
contamination from the vertex limits the precision with which the
coupling can be measured.Comment: Typeset in RevTeX4, 16 pages, 12 figures; V2: minor changes in title
and Sec. II and III; V3: version appeared in PRD with minor correctio
Bottomonia production in Modified NRQCD
Motivated by the success of Modified Non-Relativistic Quantum Chromodynamics
(Modified NRQCD) in explaining data from experiments at the Large Hadron
Collider (LHC) for charmonia, we now turn to the study of bottomonium
production at the LHC. Modified NRQCD does very well in explaining
data from the LHC. But this is true also of NRQCD which explains the
data equally well. Where the two models differ substantially is in their
predictions for production. As was the case with , the
measurement of production at the LHC will be another decisive test of
Modified NRQCD.Comment: 10 pages, 6 figure
Azimuthal Angle Probe of Anomalous HWW Couplings at the LHeC
A high energy ep collider, such as the proposed LHeC, possesses the unique
facility of permitting direct measurement of the HWW coupling without
contamination from the HZZ coupling. At such a machine, the fusion of two W
bosons through the HWW vertex would give rise to typical charged current (CC)
events accompanied by a Higgs boson. We demonstrate that azimuthal angle
correlations between the observable CC final states could then be a sensitive
probe of the nature of the HWW vertex and hence of the CP properties of the
Higgs boson.Comment: Revised version to appear in Physical Review Letters, some typos and
mis-labellings corrected, references reorganised and update
New physics contributions to the forward-backward asymmetry at the Tevatron
The Tevatron has measured a discrepancy relative to the Standard Model
prediction in the forward-backward asymmetry in top quark pair production. This
asymmetry grows with the rapidity difference of the two top quarks. It also
increases with the invariant mass of the tt pair, reaching, for high invariant
masses, 3.4 standard deviations above the Next to Leading Order prediction for
the charge asymmetry of QCD. However, perfect agreement between experiment and
the Standard Model was found in both total and differential cross section of
top quark pair production. As this result could be a sign of new physics we
have parametrized this new physics in terms of a complete set of dimension six
operators involving the top quark. We have then used a Markov Chain Monte Carlo
approach in order to find the best set of parameters that fits the data, using
all available data regarding top quark pair production at the Tevatron. We have
found that just a very small number of operators are able to fit the data
better than the Standard Model.Comment: 17 pages, 14 figure
eta_c production at the Large Hadron Collider
We have studied the production of the 1S_0 charmonium state, eta_c, at the
Large Hadron Collider (LHC) in the framework of Non-Relativistic Quantum
Chromodynamics (NRQCD) using heavy-quark symmetry. We find that NRQCD predicts
a large production cross-section for this resonance at the LHC even after
taking account the small branching ratio of eta_c into two photons. We show
that it will be possible to test NRQCD through its predictions for eta_c, with
the statistics that will be achieved at the early stage of the LHC, running at
a center of mass energy of 7 TeV with an integrated luminosity of 100 pb^{-1}Comment: 8 pages, 2 figure