1,122 research outputs found
New physics signatures at a Linear Collider: model-independent analysis from `conventional' polarized observables
We discuss four-fermion contact-interaction searches in the processes
e^+e^-\to\mu^+\mu^-, c{\bar c} and b{\bar b} at a future e^+e^- Linear Collider
with c.m. energy \sqrt{s}=0.5 TeV and with both beams longitudinally polarized.
Our analysis is based on the measurements of familiar polarized observables
such as the total cross section and the forward-backward/left-right
asymmetries, and accounts for the general set of contact interaction couplings
as independent, non-zero, parameters thus avoiding simplifying,
model-dependent, assumptions. We derive the corresponding model-independent
constraints on the above-mentioned coupling constants, and evaluate the
corresponding reach at the Linear Collider, emphasizing the role of beam
polarization. We compare the results with a model-dependent procedure where
only one coupling is varied at a time.Comment: 13 pages, including 3 figure
Eliminating the low-mass axigluon window
Using recent collider data, especially on the hadronic width the Z0, we
exclude axigluons in the currently allowed low-mass window, namely axigluons in
the mass range 50 GeV < M_A < 120 GeV. Combined with hadron collider data from
di-jet production, axigluons with masses below roughly 1 TeV are now completely
excluded.Comment: 8 pages, no figures, LaTe
Energy Conservation Constraints on Multiplicity Correlations in QCD Jets
We compute analytically the effects of energy conservation on the
self-similar structure of parton correlations in QCD jets. The calculations are
performed both in the constant and running coupling cases. It is shown that the
corrections are phenomenologically sizeable. On a theoretical ground, energy
conservation constraints preserve the scaling properties of correlations in QCD
jets beyond the leading log approximation.Comment: 11 pages, latex, 5 figures, .tar.gz version avaliable on
ftp://www.inln.unice.fr
Vector boson pair production in e-e- collisions with polarized beams
The -boson pair production in collisions with polarized beams is
investigated. The helicity amplitudes are derived for general couplings and the
conditions for a good high-energy behaviour of the cross-section are given. The
results are applied to the heavy vector boson production in the context of the
left-right symmetric model. The Ward identities and the equivalence theorem are
also discussed.Comment: 17 pages+ 8 figures(uuencoded compressed ps-file appended), HU-SEFT R
1994-09 (the original version of the file was unreproducable in some
computers
Analysis of MERCATOR data Part I: variable B stars
We re-classified 31 variable B stars which were observed more than 50 times
in the Geneva photometric system with the P7 photometer attached to the
MERCATOR telescope (La Palma) during its first 3 years of scientific
observations. HD89688 is a possible beta Cephei/slowly pulsating B star hybrid
and the main mode of the COROT target HD180642 shows non-linear effects. The
Maia candidates are re-classified as either ellipsoidal variables or spotted
stars. Although the mode identification is still ongoing, all the
well-identified modes so far have a degree l = 0, 1 or 2.Comment: 4 pages, 3 figures. To appear in: Proceedings of JENAM 2005 'Distant
worlds', Communications in Asteroseismolog
Who violates expectations when? How firms’ growth and dividend reputations affect investors’ reactions to acquisitions
Research summary: We investigate the role of a firm’s dividend and growth reputations in
shaping investors’ interpretations of acquisitions as a negative or positive expectation
violation. While our findings reveal that both an acquiring firm’s dividend and growth
reputations trigger positive investor reactions, they also show that investors react negatively
to an acquisition of a target firm with a strong growth reputation when the acquiring firm has
a strong dividend reputation. We also find that investors are inclined to give managers “the
benefit of the doubt” to the extent that an acquiring firm strategically frames an acquisition
announcement in such a way that it provides assurance to investors that the acquisition is
meant to exceed investors’ expectations about shareholder value creation.
Managerial summary: We study why investors respond to some acquisitions positively and
others negatively. We find that the way acquiring and target firms have created shareholder
value in the past, and the information conveyed in the acquisition announcements are
important determinants of investors’ differential reactions to acquisitions. Our findings show
that while investors generally react positively to acquisitions by firms known for creating
value either through dividends or growth, their reactions become negative when a firm
known for value creation through dividends acquires a target known for value creation
through growth. We further find that managers can favorably influence investor reactions by
making it salient in the acquisition announcement how the acquisition is intended to exceed
investors’ value creation expectations from the acquiring firm
Selectron Studies at e-e- and e+e- Colliders
Selectrons may be studied in both e-e- and e+e- collisions at future linear
colliders. Relative to e+e-, the e-e- mode benefits from negligible backgrounds
and \beta threshold behavior for identical selectron pair production, but
suffers from luminosity degradation and increased initial state radiation and
beamstrahlung. We include all of these effects and compare the potential for
selectron mass measurements in the two modes. The virtues of the e-e- collider
far outweigh its disadvantages. In particular, the selectron mass may be
measured to 100 MeV with a total integrated luminosity of 1 fb^-1, while more
than 100 fb^-1 is required in e+e- collisions for similar precision.Comment: 16 pages, 11 figure
Large-volume metrology instrument selection and measurability analysis
A wide range of metrology processes are involved in the manufacture of large products. In addition to the traditional tool-setting and product-verification operations, increasingly flexible metrology-enabled automation is also being used. Faced with many possible measurement problems and a very large number of metrology instruments employing diverse technologies, the selection of the appropriate instrument for a given task can be highly complex. Also, as metrology has become a key manufacturing process, it should be considered in the early stages of design, and there is currently very little research to support this. This paper provides an overview of the important selection criteria for typical measurement processes and presents some novel selection strategies. Metrics that can be used to assess measurability are also discussed. A prototype instrument selection and measurability analysis application is also presented, with discussion of how this can be used as the basis for development of a more sophisticated measurement planning tool. © 2010 Authors
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