1,784 research outputs found
Standard model higgs searches at CERN
The final result of the LEP searches for a Standard Model Higgs boson are shown. For the LHC the potential to discover a Standard Model Higgs boson, using the ATLAS and CMS detectors, is reviewed. The recent investigations into the weak boson fusion channels are discussed and results on expected measurements of Higgs boson parameters are presented
Is it the Standard Model Higgs ?
Once an excess of events in one of the Higgs boson discovery channels is found, the major task of the LHC experiments will be to verify that a Higgs boson as predicted by the Standard Model was found. This talk shows what measurements are possible at the LHC and where its intrinsic limitations are. It than concentrates on how well the Higgs boson properties - mass, width, couplings, spin, CP and self-coupling - can be measured by the LHC experiments
Gluon-induced W-boson pair production at the LHC
Pair production of W bosons constitutes an important background to Higgs
boson and new physics searches at the Large Hadron Collider LHC. We have
calculated the loop-induced gluon-fusion process gg -> W*W* -> leptons,
including intermediate light and heavy quarks and allowing for arbitrary
invariant masses of the W bosons. While formally of next-to-next-to-leading
order, the gg -> W*W* -> leptons process is enhanced by the large gluon flux at
the LHC and by experimental Higgs search cuts, and increases the
next-to-leading order WW background estimate for Higgs searches by about 30%.
We have extended our previous calculation to include the contribution from the
intermediate top-bottom massive quark loop and the Higgs signal process. We
provide updated results for cross sections and differential distributions and
study the interference between the different gluon scattering contributions. We
describe important analytical and numerical aspects of our calculation and
present the public GG2WW event generator.Comment: 20 pages, 4 figure
The Road Towards the ILC: Higgs, Top/QCD, Loops
The International Linear e+e- Collider (ILC) could go into operation in the
second half of the upcoming decade. Experimental analyses and theory
calculations for the physics at the ILC are currently performed. We review
recent progress, as presented at the LCWS06 in Bangalore, India, in the fields
of Higgs boson physics and top/QCD. Also the area of loop calculations,
necessary to achieve the required theory precision, is included.Comment: 7 pages, 1 figure. Plenary talk given at the LCWS06 March 2006,
Bangalore, India. Top part slightly enlarged, references adde
Revealing the electroweak properties of a new scalar resonance
One or more new heavy resonances may be discovered in experiments at the CERN
Large Hadron Collider. In order to determine if such a resonance is the
long-awaited Higgs boson, it is essential to pin down its spin, CP, and
electroweak quantum numbers. Here we describe how to determine what role a
newly-discovered neutral CP-even scalar plays in electroweak symmetry breaking,
by measuring its relative decay rates into pairs of electroweak vector bosons:
WW, ZZ, \gamma\gamma, and Z\gamma. With the data-driven assumption that
electroweak symmetry breaking respects a remnant custodial symmetry, we perform
a general analysis with operators up to dimension five. Remarkably, only three
pure cases and one nontrivial mixed case need to be disambiguated, which can
always be done if all four decay modes to electroweak vector bosons can be
observed or constrained. We exhibit interesting special cases of Higgs
look-alikes with nonstandard decay patterns, including a very suppressed
branching to WW or very enhanced branchings to \gamma\gamma and Z\gamma. Even
if two vector boson branching fractions conform to Standard Model expectations
for a Higgs doublet, measurements of the other two decay modes could unmask a
Higgs imposter.Comment: 23 pages, two figures; v2: minor revision and version to appear in
JHE
Theories for the Fermi Scale
I give a short review of our present understanding of new theories of the
electroweak scale, with emphasis on recent progress. Plenary talk at the EPS
2007 Conference at Manchester.Comment: 14 pages, EPS 2007 Conferenc
Measuring the Higgs Sector
If we find a light Higgs boson at the LHC, there should be many observable
channels which we can exploit to measure the relevant parameters in the Higgs
sector. We use the SFitter framework to map these measurements on the parameter
space of a general weak-scale effective theory with a light Higgs state of mass
120 GeV. Our analysis benefits from the parameter determination tools and the
error treatment used in new--physics searches, to study individual parameters
and their error bars as well as parameter correlations.Comment: 45 pages, Journal version with comments from refere
NLO Higgs boson production via vector-boson fusion matched with shower in POWHEG
We present a next-to-leading order calculation of Higgs boson production in
vector-boson fusion processes interfaced to shower Monte Carlo programs,
implemented according to the POWHEG method.Comment: 16 pages, 9 figures. A few references and a new figure adde
Model-Independent Bounds on a Light Higgs
We present up-to-date constraints on a generic Higgs parameter space. An
accurate assessment of these exclusions must take into account statistical, and
potentially signal, fluctuations in the data currently taken at the LHC. For
this, we have constructed a straightforward statistical method for making full
use of the data that is publicly available. We show that, using the expected
and observed exclusions which are quoted for each search channel, we can fully
reconstruct likelihood profiles under very reasonable and simple assumptions.
Even working with this somewhat limited information, we show that our method is
sufficiently accurate to warrant its study and advocate its use over more naive
prescriptions. Using this method, we can begin to narrow in on the remaining
viable parameter space for a Higgs-like scalar state, and to ascertain the
nature of any hints of new physics---Higgs or otherwise---appearing in the
data.Comment: 32 pages, 10 figures; v3: correction made to basis of four-derivative
operators in the effective Lagrangian, references adde
NLO Higgs boson production plus one and two jets using the POWHEG BOX, MadGraph4 and MCFM
We present a next-to-leading order calculation of Higgs boson production plus
one and two jets via gluon fusion interfaced to shower Monte Carlo programs,
implemented according to the POWHEG method. For this implementation we have
used a new interface of the POWHEG BOX with MadGraph4, that generates the codes
for generic Born and real processes automatically. The virtual corrections have
been taken from the MCFM code. We carry out a simple phenomenological study of
our generators, comparing them among each other and with fixed next-to-leading
order results.Comment: 27 pages, 21 figure
- …