2,591 research outputs found
Tevatron Discovery Potential for Fourth Generation Neutrinos: Dirac, Majorana and Everything in Between
We analyze the power of the Tevatron dataset to exclude or discover fourth
generation neutrinos. In a general framework, one can have mixed left- and
right-handed neutrinos, with Dirac and Majorana neutrinos as extreme cases. We
demonstrate that a single Tevatron experiment can make powerful statements
across the entire mixing space, extending LEP's mass limits of 60-80 GeV up to
150-175 GeV, depending on the mixing.Comment: 4 pages, pdflate
Jet measurements by the CMS experiment in pp and PbPb collisions
The energy loss of fast partons traversing the strongly interacting matter
produced in high-energy nuclear collisions is one of the most interesting
observables to probe the nature of the produced medium. The multipurpose
Compact Muon Solenoid (CMS) detector is well designed to measure these hard
scattering processes with its high resolution calorimeters and high precision
silicon tracker. Analyzing data from pp and PbPb collisions at a center-of-mass
energy of 2.76 TeV parton energy loss is observed as a significant imbalance of
dijet transverse momentum. To gain further understanding of the parton energy
loss mechanism the redistribution of the quenched jet energy was studied using
the transverse momentum balance of charged tracks projected onto the direction
of the leading jet. In contrast to pp collisions, a large fraction the momentum
balance for asymmetric jets is found to be carried by low momentum particles at
large angular distance to the jet axis. Further, the fragmentation functions
for leading and subleading jets were reconstructed and were found to be
unmodified compared to measurements in pp collisions. The results yield a
detailed picture of parton propagation in the hot QCD medium.Comment: 7 pages, 5 figures, Quark Matter 2011 conference proceeding
A Method to include Detector Effects in Estimators sensitive to the Trilinear Gauge Couplings
This paper describes the use of weighted Monte Carlo events to accurately
approximate integrals of functions of the experimentally measured kinematical
vectors and their dependence on physical parameters. This technique is
demonstrated in estimating the evolution of cross sections, efficiencies,
measured kinematical distributions and mean values as functions of the
Trilinear Gauge Couplings.Comment: 20 pages, 10 figures, Late
Using Rapidity Gaps to Distinguish Between Higgs Production by W and Gluon Fusion
The possibility of distinguishing between two higgs production mechanisms, W
fusion and gluon fusion, is investigated using the Monte Carlo event generator
PYTHIA. It is shown that, considering the designed CM energy and luminosity for
the LHC, it is not possible to distinguish between the two higgs production
processes as, for a given integrated luminosity, they lead to the same number
of events containing a rapidity gap.Comment: uudecoded compressed tar file containing a tex file and 6 figure
files. Two more figures, avaiable from the authors upon reques
Accurate Estimation of the Trilinear Gauge Couplings Using Optimal Observables Including Detector Effects
This paper describes the definition of maximum likelihood equivalent
estimators of the Trilinear Gauge Couplings which include detector effects. The
asymptotic properties of these estimators as well as their unbiasedness and
efficiency when dealing with finite statistical samples are demonstrated by
Monte Carlo experimentation, using simulated events corresponding to the
production of q qbar lepton neutrino in e+ e- collisions at 172 GeV. Emphasis
is given to the determination of the expected efficiencies in extracting the
aWphi, aW and aBphi couplings from LEPII data, which in this particular case
found to be close to the maximum possible.Comment: 32 pages, 12 figures, Late
Upper bound on the density of Ruelle resonances for Anosov flows
Using a semiclassical approach we show that the spectrum of a smooth Anosov
vector field V on a compact manifold is discrete (in suitable anisotropic
Sobolev spaces) and then we provide an upper bound for the density of
eigenvalues of the operator (-i)V, called Ruelle resonances, close to the real
axis and for large real parts.Comment: 57 page
Squark and Gluino Production with Jets
We present cross section predictions for squark and gluino production at the
LHC, in association with up to two additional hard jets. These cross sections
can be very large in comparison to the inclusive Born rates. Because hadron
collider experiments utilize hard jets in the reconstruction of cascade decays
or as a way to separate squark and gluino production, the understanding of
these processes is crucial. We show to what degree hard jet radiation can be
described by shower algorithms and point out how tuning these showers, for
example to top quark pair production, could help reduce theoretical
uncertainties for new physics searches at the LHC.Comment: 5 p, 2 fig, 1 tab; version to appear in PLB; added comments on
uncertainty estimate
Deterministic Annealing as a jet clustering algorithm in hadronic collisions
We show that a general purpose clusterization algorithm, Deterministic
Annealing, can be adapted to the problem of jet identification in particle
production by high energy collisions. In particular we consider the problem of
jet searching in events generated at hadronic colliders. Deterministic
Annealing is able to reproduce the results obtained by traditional jet
algorithms and to exhibit a higher degree of flexibility.Comment: 13 pages, 6 figure
Probabilistic Weyl laws for quantized tori
For the Toeplitz quantization of complex-valued functions on a
-dimensional torus we prove that the expected number of eigenvalues of
small random perturbations of a quantized observable satisfies a natural Weyl
law. In numerical experiments the same Weyl law also holds for ``false''
eigenvalues created by pseudospectral effects.Comment: 33 pages, 3 figures, v2 corrected listed titl
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