9,692 research outputs found
What Does the CMS Measurement of W-polarization Tell Us about the Underlying Theory of the Coupling of W-Bosons to Matter?
We discuss results of the CMS collaboration on the sensitivity of the LHC to
boson polarisation in the process using the variable directly connected to
angle of the outgoing lepton in the rest frame of the decaying . We have
shown that for a given , interference between different polarizations of
the -boson is not negligible, and needs to be taken into account when
considering the differential cross-section with respect to . The
variable suggested by CMS collaboration is highly suitable variable to study
LHC sensitivity to couplings of -boson to fermions. We note that
the experimental sensitivity to W-boson polarization which is much higher than
that to () parameter space can be turned around and used to identify
deviations from the Standard Model as a signal for new physics at the LHC.Comment: 11 pages, 8 figures. Updated to match the final version published in
JHEP with updated figures and polished tex
Associated neutralino-neutralino-photon production at NLC
We study the potential of an linear collider to search for
neutralino-neutralino-photon production. Our analysis shows that this signal is
not viable under realistic expectations for electron beam polarization due to
large Standard Model backgrounds. Such a search would be possible only if beam
polarizations of near 100% could be achieved.Comment: 3 pages, 6 figures, uses RevTeX4. Contribution to Snowmass 200
Forward-Backward Asymmetry as a Discovery Tool for Z' Bosons at the LHC
The Forward-Backward Asymmetry (AFB) in Z' physics is commonly only perceived
as the observable which possibly allows one to interpret a Z' signal by
distinguishing different models of such (heavy) spin-1 bosons. In this paper,
we examine the potential of AFB in setting bounds on or even discovering a Z'
boson at the Large Hadron Collider (LHC) and show that it might be a powerful
tool for this purpose. We analyse two different scenarios: Z' bosons with a
narrow and wide width, respectively. We find that, in the first case, the
significance of the AFB search can be comparable with that of the bump search
usually adopted by the experimental collaborations; however, being a ratio of
(differential) cross sections the AFB has the advantage of reducing
systematical errors. In the second case, the AFB search can win over the bump
search in terms of event shape, as the structure of the AFB distribution as a
function of the invariant mass of the reconstructed Z'boson could nail down the
new broad resonance much better than the event counting strategy usually
adopted in such cases.Comment: 27 pages, 17 figure
Relic density of neutralinos in minimal supergravity
We evaluate the relic density of neutralinos in the minimal supergravity
(mSUGRA) model. All 2->2 neutralino annihilation diagrams, as well as all
initial states involving sleptons, charginos, neutralinos and third generation
squarks are included. Relativistic thermal averaging of the velocity times
cross sections is performed. We find that co-annihilation effects are only
important on the edges of the model parameter space, where some amount of
fine-tuning is necessary to obtain a reasonable relic density. Alternatively,
at high tan(beta), annihilation through the broad Higgs resonances gives rise
to an acceptable neutralino relic density over broad regions of parameter space
where little or no fine-tuning is needed.Comment: LaTeX, 10 pages. Talk given by Alexander Belyaev at SUSY'02, "The
10th International Conference on Supersymmetry and Unification of Fundamental
Interactions", DESY, Hamburg, Germany, 17-23 June 200
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