1,808 research outputs found
Toptet
Final states with four tops appear in various extensions of the Standard
Model. Alas, top reconstruction faces combinatorial issues as they show up as
large multiplicity events. In this paper, we present a new procedure to
determine whether new physics is in fact due to a new source for tops. We
establish the use of this procedure to separate the signal from background
(primarily +jets). Our analysis is model independent, in that it does
not use any details of the four top production (such as possible missing
energy), and does not require b-tagging.Comment: Modifications on the manuscrip
Permutation-invariant distance between atomic configurations
We present a permutation-invariant distance between atomic configurations,
defined through a functional representation of atomic positions. This distance
enables to directly compare different atomic environments with an arbitrary
number of particles, without going through a space of reduced dimensionality
(i.e. fingerprints) as an intermediate step. Moreover, this distance is
naturally invariant through permutations of atoms, avoiding the time consuming
associated minimization required by other common criteria (like the Root Mean
Square Distance). Finally, the invariance through global rotations is accounted
for by a minimization procedure in the space of rotations solved by Monte Carlo
simulated annealing. A formal framework is also introduced, showing that the
distance we propose verifies the property of a metric on the space of atomic
configurations. Two examples of applications are proposed. The first one
consists in evaluating faithfulness of some fingerprints (or descriptors), i.e.
their capacity to represent the structural information of a configuration. The
second application concerns structural analysis, where our distance proves to
be efficient in discriminating different local structures and even classifying
their degree of similarity
Irreducible Hamiltonian BRST-anti-BRST symmetry for reducible systems
An irreducible Hamiltonian BRST-anti-BRST treatment of reducible first-class
systems based on homological arguments is proposed. The general formalism is
exemplified on the Freedman-Townsend model.Comment: LaTeX 2.09, 35 page
Dilaton constraints and LHC prospects
The Standard Model Higgs searches using the first 1-2 fb-1 of LHC data can be
used to put interesting constraints on new scalar particles other than the
Higgs. We investigate one such scenario in which electroweak symmetry is broken
via strongly coupled conformal dynamics. This scenario contains a neutral
scalar dilaton---the Goldstone boson associated with spontaneously broken scale
invariance---with a mass below the conformal symmetry breaking scale and
couplings to Standard Model particles similar (but not identical) to those of
the Standard Model Higgs boson. We translate the LEP and LHC Higgs limits to
constrain the dilaton mass and conformal breaking scale. The conformal breaking
scale f is constrained to be above 1 TeV for dilaton masses between 145 and 600
GeV, though it can be as low as 400 GeV for dilaton masses below 110 GeV. We
also show that (i) a dilaton chi with mass below 110 GeV and consistent with
the LEP constraints can appear in gg --> chi --> gamma gamma with a rate up to
~10 times the corresponding Standard Model Higgs rate, and (ii) a dilaton with
mass of several hundred GeV is much narrower than the corresponding Standard
Model Higgs, leading to improved search sensitivity in chi --> ZZ --> 4l.Comment: 15 pages, 12 figures, References added, Figure 10 modified, Figure 11
adde
Triplectic Gauge Fixing for N=1 Super Yang-Mills Theory
The Sp(2)-gauge fixing of N = 1 super-Yang-Mills theory is considered here.
We thereby apply the triplectic scheme, where two classes of gauge-fixing
bosons are introduced. The first one depends only on the gauge field, whereas
the second boson depends on this gauge field and also on a pair of Majorana
fermions. In this sense, we build up the BRST extended (BRST plus antiBRST)
algebras for the model, for which the nilpotency relations,
s^2_1=s^2_2=s_1s_2+s_2s_1=0, hold.Comment: 10 pages, no figures, latex forma
Triplectic Quantization of W2 gravity
The role of one loop order corrections in the triplectic quantization is
discussed in the case of W2 theory. This model illustrates the presence of
anomalies and Wess Zumino terms in this quantization scheme where extended BRST
invariance is represented in a completely anticanonical form.Comment: 10 pages, no figure
Quantum cloning with an optical fiber amplifier
It has been shown theoretically that a light amplifier working on the
physical principle of stimulated emission should achieve optimal quantum
cloning of the polarization state of light. We demonstrate close-to-optimal
universal quantum cloning of polarization in a standard fiber amplifier for
telecom wavelengths. For cloning 1 --> 2 we find a fidelity of 0.82, the
optimal value being 5/6 = 0.83.Comment: 4 pages, 3 figure
Macroscopic dynamics of the fusion process
A macroscopic dynamical model has been used to calculate fusion cross sections for a wide number of systems ranging from 16O + 27Al to 40Ar + 165Ho. This model takes into account the reorganization of the densities and the nucleon exchanges. The possible reaction mechanisms after capture of the system into the pocket of the interaction potential are discussed Two processes contribute to fusion : compound nucleus formation and fast fission phenomenon. The calculated fusion cross sections are in overall agreement with the data
Physiological requirements in triathlon
This article aims to present the current knowledge on physiological requirements in Olympic distance and Ironman triathlon. Showing the data available from a âtraditional point of viewâ (aerobic power, anaerobic threshold, heart rate, running economy) and from a âcontemporaryâ point of view (VÌ O2 kinetics), it emphasises where we are currently and the areas that remain unknown
- âŠ