13 research outputs found
Higgs pair production in association with a vector boson at e+e- colliders in theories of higher dimensional gravity
The models of large extra compact dimensions, as suggested by Arkani-Hamed,
Dimopoulos and Dvali, predict exciting phenomenological consequences with
gravitational interactions becoming strong at the TeV scale. Such theories can
be tested at the existing and future colliders. In this paper, we study the
contribution of virtual Kaluza-Klein excitations (both spin-0 and 2) in the
process and at future linear collider
(NLC). We find that the virtual exchange KK gravitons can modify the
cross-section significantly from its Standard Model
value and will allow the effective string scale to be probed up to 6.6 TeV. The
second process is absent at the tree level in the standard model, and can
therefore be used to put limits on the effective string scale of 7.4 TeV.Comment: One new reference is added, some minor corrections, version to appear
in Physical Review
Extracting W Boson Couplings from the Production of Four Leptons
We consider the processes , including all possible charged lepton combinations, with
regard to measuring parameters characterizing the boson. We calculate at
what level these processes can be used to measure anamolous triple-boson
vertice coupling parameters for the cases of colliders at 500
and 1 center of mass energies.Comment: 13 pages,OCIP/C-93-
Bounds on the tau and muon neutrino vector and axial vector charge radius
A Majorana neutrino is characterized by just one flavor diagonal
electromagnetic form factor: the anapole moment, that in the static limit
corresponds to the axial vector charge radius . Experimental information
on this quantity is scarce, especially in the case of the tau neutrino. We
present a comprehensive analysis of the available data on the single photon
production process off Z-resonance, and we
discuss the constraints that these measurements can set on for the tau
neutrino. We also derive limits for the Dirac case, when the presence of a
vector charge radius is allowed. Finally, we comment on additional
experimental data on scattering from the NuTeV, E734, CCFR and
CHARM-II collaborations, and estimate the limits implied for and
for the muon neutrino.Comment: 20 pages, 2 eps figures. CCFR data included in the analysis.
Conclusion unchange
Planck scale effects in neutrino physics
We study the phenomenology and cosmology of the Majoron (flavon) models of
three active and one inert neutrino paying special attention to the possible
(almost) conserved generalization of the Zeldovich-Konopinski-Mahmoud lepton
charge. Using Planck scale physics effects which provide the breaking of the
lepton charge, we show how in this picture one can incorporate the solutions to
some of the central issues in neutrino physics such as the solar and
atmospheric neutrino puzzles, dark matter and a 17 keV neutrino. These
gravitational effects induce tiny Majorana mass terms for neutrinos and
considerable masses for flavons. The cosmological demand for the sufficiently
fast decay of flavons implies a lower limit on the electron neutrino mass in
the range of 0.1-1 eV.Comment: 24 pages, 1 figure (not included but available upon request), LaTex,
IC/92/196, SISSA-140/92/EP, LMU-09/9
Model-independent analysis of Higgs spin and CP properties in the process
In this paper we investigate methods to study the Higgs coupling.
The spin and CP properties of a Higgs boson are analysed in a model-independent
way in its associated production with a pair in high-energy
collisions. We study the prospects of establishing the CP quantum numbers of
the Higgs boson in the CP-conserving case as well as those of determining the
CP-mixing if CP is violated. We explore in this analysis the combined use of
the total cross section and its energy dependence, the polarisation asymmetry
of the top quark and the up-down asymmetry of the antitop with respect to the
top-electron plane. We find that combining all three observables remarkably
reduces the error on the determination of the CP properties of the Higgs Yukawa
coupling. Furthermore, the top polarisation asymmetry and the ratio of cross
sections at different collider energies are shown to be sensitive to the spin
of the particle produced in association with the top quark pair