1,631 research outputs found
Prospects for Observing an Invisibly Decaying Higgs Boson in the t anti-t H Production at the LHC
The prospects for observing an invisibly decaying Higgs boson in the t anti-t
H production at LHC are discussed. An isolated lepton, reconstructed hadronic
top-quark decay, two identified b-jets and large missing transverse energy are
proposed as the final state signature for event selection. Only the Standard
Model backgrounds are taken into account. It is shown that the t anti-t Z, t
anti-t W, b anti-b Z and b anti-b W backgrounds can individually be suppressed
below the signal expectation. The dominant source of background remains the t
anti-t production. The key for observability will be an experimental selection
which allows further suppression of the contributions from the t anti-t events
with one of the top-quarks decaying into a tau lepton. Depending on the details
of the final analysis, an excess of the signal events above the Standard Model
background of about 10% to 100% can be achieved in the mass range m_H= 100-200
GeV.Comment: Final version as accepted by EPJ
A Consistent Prescription for Combining Perturbative Calculations and Parton Showers in Case of Associated Z b anti-b Hadroproduction
This paper presents the method of combining parton shower formalism with
perturbative calculations (matrix elements) in form of a Monte-Carlo algorithm
for the process g g -> Z b anti-b,consistenlty including the heavy quark masses
and overlap removal.Comment: accepted by JHEP, revised according to suggestions from JHEP refere
Improved Phase Space Treatment of Massive Multi-Particle Final States
In this paper the revised Kajantie-Byckling approach and improved phase space
sampling techniques for the massive multi-particle final states are presented.
The application of the developed procedures to the processes representative for
LHC physics indicates the possibility of a substantial simplification of
multi-particle phase space sampling while retaining a respectable weight
variance reduction and unweighing efficiencies in the event generation process.Comment: Minor stilistic changes, submitted to EPJ
ATLAS Physics Potential
The presentations give a brief overview of the ATLAS physics potential in the forthcoming LHC era as a series of three lectures
Les Houches Guidebook to Monte Carlo Generators for Hadron Collider Physics
Recently the collider physics community has seen significant advances in the
formalisms and implementations of event generators. This review is a primer of
the methods commonly used for the simulation of high energy physics events at
particle colliders. We provide brief descriptions, references, and links to the
specific computer codes which implement the methods. The aim is to provide an
overview of the available tools, allowing the reader to ascertain which tool is
best for a particular application, but also making clear the limitations of
each tool.Comment: 49 pages Latex. Compiled by the Working Group on Quantum
ChromoDynamics and the Standard Model for the Workshop ``Physics at TeV
Colliders'', Les Houches, France, May 2003. To appear in the proceeding
Probing for Invisible Higgs Decays with Global Fits
We demonstrate by performing a global fit on Higgs signal strength data that
large invisible branching ratios Br_{inv} for a Standard Model (SM) Higgs
particle are currently consistent with the experimental hints of a scalar
resonance at the mass scale m_h ~ 124 GeV. For this mass scale, we find
Br_{inv} < 0.64 (95 % CL) from a global fit to individual channel signal
strengths supplied by ATLAS, CMS and the Tevatron collaborations. Novel tests
that can be used to improve the prospects of experimentally discovering the
existence of a Br_{inv} with future data are proposed. These tests are based on
the combination of all visible channel Higgs signal strengths, and allow us to
examine the required reduction in experimental and theoretical errors in this
data that would allow a more significantly bounded invisible branching ratio to
be experimentally supported. We examine in some detail how our conclusions and
method are affected when a scalar resonance at this mass scale has couplings
deviating from the SM ones.Comment: 32pp, 15 figures v2: JHEP version, ref added & comment added after
Eq.
QCD corrections to electroweak l nu_l jj and l^+ l^- jj production
The production of W or Z bosons in association with two jets is an important
background to the Higgs boson search in vector-boson fusion at the LHC. The
purely electroweak component of this background is dominated by vector-boson
fusion, which exhibits kinematic distributions very similar to the Higgs boson
signal. We consider the next-to-leading order QCD corrections to the
electroweak production of l nu_l jj and l^+ l^- jj events at the LHC, within
typical vector-boson fusion cuts. We show that the QCD corrections are modest,
increasing the total cross sections by about 10%. Remaining scale uncertainties
are below 2%. A fully-flexible next-to-leading order partonic Monte Carlo
program allows to demonstrate these features for cross sections within typical
vector-boson-fusion acceptance cuts. Modest corrections are also found for
distributions.Comment: 26 pages, 10 figures. PRD final version. One reference corrected,
introduction expande
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