754 research outputs found
Tests of Higgs Boson Couplings at a mu+mu- Collider
We investigate the potential of a muon collider for testing the presence of
anomalous Higgs boson couplings. We consider the case of a light (less than
) Higgs boson and study the effects on the Higgs branching ratios and
total width, which could be induced by the non standard couplings created by a
class of dim=6 gauge invariant operators
satisfying the constraints imposed by the present and future hadronic and
colliders. For each operator we give the minimal value of the
integrated luminosity needed for the muon collider () to
improve these constraints. Depending on the operator and the Higgs mass, this
minimal luminosity lies between and .Comment: 18 pages and 4 figures; version to be published in Phys. Rev.D.
e-mail: [email protected]
Signals for Low Scale Gravity in the Process
We investigate the sensitivity of future photon-photon colliders to low scale
gravity scenarios via the process where the Kaluza-Klein
boson exchange contributes only when the initial state photons have opposite
helicity. We contrast this with the situation for the process where the and channel also contribute. We include
the one-loop Standard Model background whose interference with the graviton
exchange determines the experimental reach in measuring any deviation from the
Standard Model expectations and explore how polarization can be exploited to
enhance the signal over background. We find that a 1 TeV linear collider has an
experimental reach to mass scale of about 4 TeV in this channel.Comment: 20 pages, 8 figure
Signatures of the anomalous and ZZ production at the lepton and hadron Colliders
The possible form of New Physics (NP) interactions affecting the ZZZ, and vertices, is critically examined. Their signatures
and the possibilities to study them, through ZZ and production, at
the e^-e^+ Colliders LEP and LC and at the hadronic Colliders Tevatron and LHC,
are investigated. Experimental limits obtained or expected on each coupling are
collected. A simple theoretical model based on virtual effects due to some
heavy fermions is used for acquiring some guidance on the plausible forms of
these NP vertices. In such a case specific relations among the various neutral
couplings are predicted, which can be experimentally tested and possibly used
to constrain the form of the responsible NP structure.Comment: 17 pages and 9 figures, version to appear in Phys. ReV. e-mail:
[email protected]
Implications for and Modes from Observed Large
The unexpectedly large branching ratios for decays
could be of gluonic origin. We study the implications for and , where is the pseudoscalar glueball. In the
mechanism proposed by Fritzsch, large branching ratios are predicted for these
modes. The rate is barely within the experimental limit, and
, could be at the 0.1% and 1% level, respectively. Smaller but
less definite results are found for the mechanism of via the
gluon anomaly.Comment: 11 pages, revtex, no fig
Testing the Higgs boson gluonic couplings at LHC
We study Higgs + jet production at hadron colliders in order to look for new
physics residual effects possibly described by the operators
{\O}_{GG} and {\widetilde\O}_{GG} which induce anomalous and
couplings. Two ways for constraining these operators at LHC may be ~useful. The
first is based on the total Higgs boson production rate induced by gluon-gluon
fusion, in which the main cause of limitations are due to theoretical
uncertainties leading to sensitivities of and
for the corresponding anomalous
couplings, in the mass range 100 GeV \lsim \mh \lsim 2~00 GeV. These results
imply sensitivity to new physics scales of 51 and 24 TeV respectively. The
second way investigated here concerns the shape of the Higgs transverse
momentum; for which the theoretical uncertainties are less severe and the
limitations are mainly induced by statistics. A simple analysis, based on the
ratio of the number of events at large and low at LHC, leads to similar
sensitivities, if only the decay mode is used. But the
sensitivities can now be improved by a factor 2 to 10, depending on the Higgs
mass, if the Higgs decay modes to , , , are also used.Comment: 23 pages and 7 figures, version to appear in Phys.ReV.D. e-mail:
[email protected]
Little Higgs model effects in
Though the predictions of the Standard Model (SM) are in excellent agreement
with experiments there are still several theoretical problems associated with
the Higgs sector of the SM, where it is widely believed that some ``{\it new
physics}'' will take over at the TeV scale. One beyond the SM theory which
resolves these problems is the Little Higgs (LH) model. In this work we have
investigated the effects of the LH model on \gggg scattering
\cite{Choudhury:2006xa}.Comment: Talk given at LCWS06, Bangalore, 4 pages (style files included
How to reduce the negative impact of customer non-compliance: an empirical study
This article focuses on the notion of customer non-compliance with front-line employees' instructions and company's policies during the service encounter. The aim of the study is to offer an alternative solution to the issue of customer non-compliance, exploring the factors that reduce its negative impact on service quality. For that reason, we developed a conceptual framework integrating the negative influence of customer non-compliance on perceived service quality with three moderating effects. To test the validity of the framework, a hierarchical approach was followed and data were collected from 120 managers and 585 customers of 120 hotels. The results confirm the negative influence of customer non-compliance on perceived service quality and indicate three organizational factors as reducing moderators of this influence: customer orientation, service blueprinting effectiveness and employee empowerment. Based on these conclusions, important implications for academics and practitioners are drawn
Gauge boson couplings at LEP
A review is given of the measurements of triple and quartic couplings among
the electroweak gauge bosons performed at LEP by the four experiments ALEPH,
DELPHI, L3 and OPAL. Emphasis is placed on recently published results and on
combinations of results performed by the LEP electroweak gauge-couplings group.
All measurements presented are consistent with the Standard Model expectations.Comment: 6 pages, 7 figures. To be published in the proceedings of the BEACH04
conference, Chicago, June 27-July 3 200
Coherent pion production by neutrinos on nuclei
The main part of coherent pion production by neutrinos on nuclei is
essentially determined by PCAC, provided that the leptonic momentum transferred
square Q^2 remains sufficiently small. We give the formulas for the charged and
neutral current cross sections, including also the small non-PCAC transverse
current contributions and taking into account the effect of the \mu^- mass. Our
results are compared with the experimental ones and other theoretical
treatments.Comment: 18 pages, 4 figure
RacoonWW1.3: A Monte Carlo program for four-fermion production at e^+ e^- colliders
We present the Monte Carlo generator RacoonWW that computes cross sections to
all processes e^+ e^- -> 4f and e^+ e^- -> 4f + gamma and calculates the
complete O(alpha) electroweak radiative corrections to e^+ e^- -> W W -> 4f in
the electroweak Standard Model in double-pole approximation. The calculation of
the tree-level processes e^+ e^- -> 4f and e^+ e^- -> 4f + gamma is based on
the full matrix elements for massless (polarized) fermions. When calculating
radiative corrections to e^+ e^- -> W W -> 4f the complete virtual
doubly-resonant electroweak corrections are included, i.e. the factorizable and
non-factorizable virtual corrections in double-pole approximation, and the real
corrections are based on the full matrix elements for e^+ e^- -> 4f + gamma.
The matching of soft and collinear singularities between virtual and real
corrections is done alternatively in two different ways, namely by using a
subtraction method or by applying phase-space slicing. Higher-order
initial-state photon radiation and naive QCD corrections are taken into
account. RacoonWW also provides anomalous triple gauge-boson couplings for all
processes e^+ e^- -> 4f and anomalous quartic gauge-boson couplings for all
processes e^+ e^- -> 4f + gamma.Comment: 62 pages, LaTeX, elsart styl
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