319 research outputs found
Measuring spin and CP from semi-hadronic ZZ decays using jet substructure
We apply novel jet techniques to investigate the spin and CP quantum numbers
of a heavy resonance X, singly produced in pp -> X -> ZZ -> l(+)l(-)jj at the
LHC. We take into account all dominant background processes to show that this
channel, which has been considered unobservable until now, can qualify under
realistic conditions to supplement measurements of the purely leptonic decay
channels X -> ZZ -> 4l. We perform a detailed investigation of spin- and
CP-sensitive angular observables on the fully-simulated final state for various
spin and CP quantum numbers of the state X, tracing how potential sensitivity
communicates through all the steps of a subjet analysis. This allows us to
elaborate on the prospects and limitations of performing such measurements with
the semihadronic final state. We find our analysis particularly sensitive to a
CP-even or CP-odd scalar resonance, while, for tensorial and vectorial
resonances, discriminative features are diminished in the boosted kinematical
regime.Comment: 12 pages, 7 figures, 2 tables, published versio
Precise predictions for (non-standard) W+photon+jet production
We report on a detailed investigation of the next-to-leading order (NLO) QCD
corrections to +jet production at the Tevatron and the LHC using a
fully-flexible parton-level Monte Carlo program. We include the full leptonic
decay of the , taking into account all off-shell and finite width effects,
as well as non-standard couplings. We find particularly sizable
corrections for the currently allowed parameter range of anomalous couplings
imposed by LEP data. In total the NLO differential distributions reveal a
substantial phase space dependence of the corrections, leaving considerable
sensitivity to anomalous couplings beyond scale uncertainty at large momentum
transfers in the anomalous vertex.Comment: 22 pages, 14 figures, 2 tables, published versio
Ditau jets in Higgs searches
Understanding and identifying ditau jets -- jets consisting of pairs of tau
particles, can be of crucial importance and may even turn out to be a necessity
if the Higgs boson decays dominantly to new light scalars which, on the other
hand, decay to tau pairs. As often seen in various models of BSM such as in the
NMSSM, Higgs portals etc., the lightness of these new states ensures their
large transverse momenta and, as a consequence, the collinearity of their decay
products. We show that the non-standard signatures of these objects, which can
easily be missed by standard analysis techniques, can be superbly exploited in
an analysis based on subjet observables. When combined with additional
selection strategies, this analysis can even facilitate an early discovery of
the Higgs boson. To be specific, a light Higgs can be found with from of data. We combine all these
observables into a single discriminating likelihood that can be employed toward
the construction of a realistic and standalone ditau tagger.Comment: 9 pages, 9 figures. References added, typos corrected, published
versio
Reconstructing the invisible with matrix elements
We propose a fully flexible method to perform an hypothesis test between
signal and background based on the Matrix Element Method in the presence of
multiple invisible particles. The proposed method performs a mapping of the
measured final state onto its minimal hypersurface of degrees of freedom for a
given process and then maximises the matrix element on this hypersurface
separately for signal and background. To show how performant the method is in
separating signal from background, we apply it to the prominent partly
invisible decay of a Higgs boson into a muon-antimuon pair and two
muon-neutrinos via two W bosons.Comment: 4 page
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