1,074 research outputs found
The CP properties of the lightest Higgs boson with sbottom effects
In the framework of the recently proposed gluino-axion model, using the
effective potential method and taking into account the top-stop as well as the
bottom-sbottom effects, we discuss the CP--properties of the lightest Higgs
boson, in particular its CP--odd composition, which can offer new opportunities
at collider searches. It is found that although the CP-odd composition of the
lightest Higgs increases slightly with the inclusion of the sbottom effects, it
never exceeds %0.17 for all values of the renormalization scale Q ranging from
top mass to TeV scaleComment: 24 pp, 12 eps fig
Data Preservation at LEP
The four LEP experiments ALEPH, DELPHI, L3 and OPAL successfully recorded
e+e- collision data during the years 1989 to 2000. As part of the ordinary
evolution in High Energy Physics, these experiments can not be repeated and
their data is therefore unique. This article briefly reviews the data
preservation efforts undertaken by the four experiments beyond the end of data
taking. The current status of the preserved data and associated tools is
summarised.Comment: 7 pages, contribution to proceedings of the "First Workshop on Data
Preservation and Long Term Analysis in HEP
with a production
The cross section of
process with a complete set of tree diagrams, 232 diagrams in the unitary
gauge, was calculated at the energy range of = 340 - 500 GeV by
using GRACE system. A main contribution to the cross section comes from
production, where and decay into and
, respectively. It was found that the
interference between the diagrams with production and those with
single- through pair production amounts to 10% at the
threshold energy region. In the energy region above twice of the top quark
mass, more than 95% of the cross section comes from the diagrams.Comment: 17 pages, 8 PostScript figures, LateX; To appear in Phys. Lett.
NLO corrections to differential cross sections for pseudo-scalar Higgs boson production
We have computed the full next-to-leading (NLO) QCD corrections to the
differential distributions for pseudo-scalar Higgs (A)
production at large hadron colliders. This calculation has been carried out
using the effective Lagrangian approach which is valid as long as the mass of
the pseudo-scalar Higgs boson and its transverse momentum do
not exceed the top-quark mass . The shape of the distributions hardly
differ from those obtained for scalar Higgs (H) production because, apart from
the overall coupling constant and mass, there are only small differences
between the partonic differential distributions for scalar and pseudo-scalar
production. Therefore there are only differences in the magnitudes of the
hadronic differential distributions which can be mainly attributed to the
unknown mixing angle describing the pseudo-scalar Higgs coupling to the
top quarks.Comment: 9 pages, LaTeX, 3 Postscript figures In the previous version we have
forgotten to include contributions which arrise from interferences between
graphs containing vertices corresponding to the operator in Eq. (3)
with graphs originating from the operator . These interferences occur
because of the prescription for the Levi-Civita tensor given in our paper.
These extra contributions are added to Eqs. (19) and (20). Numerically they
are completely negligible so that the figures are not altere
First results of the SOAP project. Open access publishing in 2010
The SOAP (Study of Open Access Publishing) project has compiled data on the
present offer for open access publishing in online peer-reviewed journals.
Starting from the Directory of Open Access Journals, several sources of data
are considered, including inspection of journal web site and direct inquiries
within the publishing industry. Several results are derived and discussed,
together with their correlations: the number of open access journals and
articles; their subject area; the starting date of open access journals; the
size and business models of open access publishers; the licensing models; the
presence of an impact factor; the uptake of hybrid open access.Comment: Submitted to PLoS ON
Highlights from the SOAP project survey. What Scientists Think about Open Access Publishing
The SOAP (Study of Open Access Publishing) project has run a large-scale
survey of the attitudes of researchers on, and the experiences with, open
access publishing. Around forty thousands answers were collected across
disciplines and around the world, showing an overwhelming support for the idea
of open access, while highlighting funding and (perceived) quality as the main
barriers to publishing in open access journals. This article serves as an
introduction to the survey and presents this and other highlights from a
preliminary analysis of the survey responses. To allow a maximal re-use of the
information collected by this survey, the data are hereby released under a CC0
waiver, so to allow libraries, publishers, funding agencies and academics to
further analyse risks and opportunities, drivers and barriers, in the
transition to open access publishing.Comment: Data manual available at http://bit.ly/gI8nct Compressed CSV data
file available at http://bit.ly/gSmm71 Alternative data formats: CSV
http://bit.ly/ejuvKO XLS http://bit.ly/e6gE7o XLSX http://bit.ly/gTjyv
Testing the Higgs Sector of the Minimal Supersymmetric Standard Model at Large Hadron Colliders
We study the Higgs sector of the Minimal Supersymmetric Standard Model, in
the context of proton-proton collisions at LHC and SSC energies. We assume a
relatively heavy supersymmetric particle spectrum, and include recent results
on one-loop radiative corrections to Higgs-boson masses and couplings. We begin
by discussing present and future constraints from the LEP experiments. We then
compute branching ratios and total widths for the neutral () and charged
() Higgs particles. We present total cross-sections and event rates for
the important discovery channels at the LHC and SSC. Promising physics
signatures are given by , or or , , and followed by
, which should allow for an almost complete coverage
of the parameter space of the model.Comment: 51 pages, 30 figures (not enclosed and not available via e-mail
A gobal fit to the anomalous magnetic moment, b->s gamma and Higgs limits in the constrained MSSM
New data on the anomalous magnetic moment a_mu of the muon together with the
b->s gamma decay rate are considered within the supergravity inspired
constrained minimal supersymmetric model. We perform a global statistical chi^2
analysis of these data and show that the allowed region of parameter space is
bounded from below by the Higgs limit, which depends on the trilinear coupling
and from above by the anomalous magnetic moment a_mu. The newest b->s gamma
data deviate 1.7 sigma from recent SM calculations and prefer a similar
parameter region as the 2.6 sigma deviation from a_mu.Comment: 12 pages, 7 figs. Refs. update
How Finely Tuned is Supersymmetric Dark Matter?
We introduce a quantification of the question in the title: the logarithmic
sensitivity of the relic neutralino density Omega-hsquared to variations in
input parameters such as the supersymmetric mass scales m_0, m_1/2 and A_0, tan
beta and the top and bottom quark masses. In generic domains of the CMSSM
parameter space with a relic density in the preferred range 0.1 <
Omega-hsquared < 0.3, the sensitivities to all these parameters are moderate,
so an interesting amount of supersymetric dark matter is a natural and robust
prediction. Within these domains, the accuracy in measuring the CMSSM and other
input parameters at the LHC may enable the relic density to be predicted quite
precisely. However, in the coannihilation regions, this might require more
information on the supersymetric spectrum than the LHC is able to provide.
There are also exceptional domains, such as those where direct-channel pole
annihilation dominates, and in the `focus-point' region, where the logarithmic
sensitivity to the input parameters is greatly increased, and it would be more
difficult to predict Omega-hsquared accurately.Comment: 14 pages, 2 eps figure
The Stau Neutralino Co-annihilation Region at an International Linear Collider
We probe the stau-neutralino co-annihilation domain of the parameter space
allowed by the current experimental bounds on the light Higgs mass, the b-> s
\gamma decay, and the amount of neutralino cold dark matter within the
framework of minimal SUGRA models at a 500 GeV e+e- linear collider. The most
favorable signals of SUSY are stau pair production and neutralino pair
production where the small mass difference between the lighter stau and the
lightest neutralino in the co-annihilation region is ~5-15 GeV and hence
generates low-energy tau leptons in the final state. This small mass difference
would be a striking signal of many SUGRA models. We find that a calorimeter
covering down to 1^o from the beams is crucial to reduce the two-photon
background and the mass difference could be measured at a level of 10% with 500
fb^-1 of data where an invariant mass of two-tau jets and missing energy is
used as a discriminator.Comment: 17 pages, 7 figure
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