68,825 research outputs found
Presymmetry beyond the Standard Model
We go beyond the Standard Model guided by presymmetry, the discrete
electroweak quark-lepton symmetry hidden by topological effects which explain
quark fractional charges as in condense matter physics. Partners of the
particles of the Standard Model and the discrete symmetry associated with this
partnership appear as manifestations of a residual presymmetry and its
extension from matter to forces. This duplication of the spectrum of the
Standard Model keeps spin and comes nondegenerated about the TeV scale.Comment: 6 pages, 11 figures. To be published in the proceedings of DPF-2009,
Detroit, MI, July 2009, eConf C09072
Perfluoro (Imidoylamidine) diamidines
Perfluoroether triazine elastomers having improved properties are prepared from oligomeric imidoylamidines that were in turn, prepared by the process of: (1) reacting a perfluorodinitrile with liquid ammonia to yield a perfluorodiamidine, (2) isolating the perfluorodiamidine, (3) reacting the isolated diamidine with a perfluorodinitrile to yield a perfluoro(imidoylamidine) dinitrile, and then repeating the steps to sequentially grow an oligomer of desired molecular size. The isolated amidine and nitrile intermediates are also disclosed. The elastomers can be fashioned into seals, gaskets, and sealing components and the like
Process for preparing perfluorotriazine elastomers and precursors thereof
Perfluoroether triazine elastomers having improved properties and utility in seals, gaskets, sealing components and the like are prepared from oligomeric imidoylamidines that have, in turn, been prepared by the process of (1) reacting a perfluorodinitrile with liquid ammonia to yield a perfluorodiamidine, (2) isolating the perfluorodiamidine, (3) reacting the isolated diamidine with a perfluorodinitrile to yield a perfluoror(imidoylamidine) dinitrile, and then repeating step (1), (2), and (3) to sequentially grow an oligomer of desired molecular size. The isolated amidine and nitrile intermediates are also described
Learning Points and Routes to Recommend Trajectories
The problem of recommending tours to travellers is an important and broadly
studied area. Suggested solutions include various approaches of
points-of-interest (POI) recommendation and route planning. We consider the
task of recommending a sequence of POIs, that simultaneously uses information
about POIs and routes. Our approach unifies the treatment of various sources of
information by representing them as features in machine learning algorithms,
enabling us to learn from past behaviour. Information about POIs are used to
learn a POI ranking model that accounts for the start and end points of tours.
Data about previous trajectories are used for learning transition patterns
between POIs that enable us to recommend probable routes. In addition, a
probabilistic model is proposed to combine the results of POI ranking and the
POI to POI transitions. We propose a new F score on pairs of POIs that
capture the order of visits. Empirical results show that our approach improves
on recent methods, and demonstrate that combining points and routes enables
better trajectory recommendations
The Universal Real Projective Plane: LHC phenomenology at one Loop
The Real Projective Plane is the lowest dimensional orbifold which, when
combined with the usual Minkowski space-time, gives rise to a unique model in
six flat dimensions possessing an exact Kaluza Klein (KK) parity as a relic
symmetry of the broken six dimensional Lorentz group. As a consequence of this
property, any model formulated on this background will include a stable Dark
Matter candidate. Loop corrections play a crucial role because they remove mass
degeneracy in the tiers of KK modes and induce new couplings which mediate
decays. We study the full one loop structure of the corrections by means of
counter-terms localised on the two singular points. As an application, the
phenomenology of the (2,0) and (0,2) tiers is discussed at the LHC. We identify
promising signatures with single and di-lepton, top antitop and 4 tops: in the
dilepton channel, present data from CMS and ATLAS may already exclude KK masses
up to 250 GeV, while by next year they may cover the whole mass range preferred
by WMAP data.Comment: 45 pages, 3 figure
Sandstone Pore Aspect Ratio Spectra from Direct Observations and Velocity Inversion
Measurements of pore shapes from Scanning Electron Microscope (SEM) images
for three sandstone samples (the Navajo Sandstone, the Weber Sandstone, and the
Kayenta Sandstone) are compared to the aspect ratio spectra obtained from
inverting laboratory velocity versus pressure data using the method of Cheng and
Toksoz (1979). The results indicate that the inversion method is in very good
agreement with the observations at high aspect ratios ( ex > 0.0 1). At low aspect ratios the agreement is very good for the clean Navajo Sandstone sample, but poor
for the Weber and Kayenta samples which contain clay. The Navajo sample is
composed chiefly of quartz with significant pressure dissolution apparent along grain
contacts resulting in smooth, flat cracks between grains. The Weber and Kayenta
samples have rougher crack surfaces as well as tapered pore edges, indicating that
asperities ,and non-elliptical pore shapes may result in an over estimation of low
aspect ratio cracks by velocity inversion. The presence of degraded feldspars may
also play a role.Phillips Petroleum Fellowshi
Missing Momentum Reconstruction and Spin Measurements at Hadron Colliders
We study methods for reconstructing the momenta of invisible particles in
cascade decay chains at hadron colliders. We focus on scenarios, such as SUSY
and UED, in which new physics particles are pair produced. Their subsequent
decays lead to two decay chains ending with neutral stable particles escaping
detection. Assuming that the masses of the decaying particles are already
measured, we obtain the momenta by imposing the mass-shell constraints. Using
this information, we develop techniques of determining spins of particles in
theories beyond the standard model. Unlike the methods relying on Lorentz
invariant variables, this method can be used to determine the spin of the
particle which initiates the decay chain. We present two complementary ways of
applying our method by using more inclusive variables relying on kinematic
information from one decay chain, as well as constructing correlation variables
based on the kinematics of both decay chains in the same event.Comment: Version to appear in JHE
Elastic Scattering and Direct Detection of Kaluza-Klein Dark Matter
Recently a new dark matter candidate has been proposed as a consequence of
universal compact extra dimensions. It was found that to account for
cosmological observations, the masses of the first Kaluza-Klein modes (and thus
the approximate size of the extra dimension) should be in the range 600-1200
GeV when the lightest Kaluza-Klein particle (LKP) corresponds to the
hypercharge boson and in the range 1 - 1.8 TeV when it corresponds to a
neutrino. In this article, we compute the elastic scattering cross sections
between Kaluza-Klein dark matter and nuclei both when the lightest Kaluza-Klein
particle is a KK mode of a weak gauge boson, and when it is a neutrino. We
include nuclear form factor effects which are important to take into account
due to the large LKP masses favored by estimates of the relic density. We
present both differential and integrated rates for present and proposed
Germanium, NaI and Xenon detectors. Observable rates at current detectors are
typically less than one event per year, but the next generation of detectors
can probe a significant fraction of the relevant parameter space.Comment: 23 pages, 11 figures; v2,v3: Ref. added, discussion improved,
conclusions unchanged. v4: Introduction was expanded to be more appropriate
for non experts. Various clarifications added in the text. Version to be
published in New Journal of Physic
Enhancement of perfluorooctanoate and perfluorooctanesulfonate activity at acoustic cavitation bubble interfaces
Acoustic cavitation driven by ultrasonic irradiation decomposes and mineralizes the recalcitrant perfluorinated surfactants perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). Pyrolytic cleavage of the ionic headgroup is the rate-determining step. In this study, we examine the sonochemical adsorption of PFOX, where X = S for PFOS and A for PFOA, by determining kinetic order and absolute rates over an initial PFOX concentration range of 20 nM to 200 μM. Sonochemical PFOX kinetics transition from pseudo-first-order at low initial concentrations, [PFOX]_i 40 μM, as the bubble interface sites are saturated. At PFOX concentrations below 100 μM, concentration-dependent rates were modeled with Langmuir−Hinshelwood (LH) kinetics. Empirically determined rate maximums, V_(Max)^(−PFOA) = 2230 ± 560 nM min^−1 and V_(Max)^(−PFOS) = 230 ± 60 nM min^−1, were used in the LH model, and sonochemical surface activities were estimated to be K_(Sono)^(PFOS) = 120000 M^−1 and K_(Sono)^(PFOA) = 28500 M^−1, 60 and 80 times greater than equilibrium surface activities, K_(Eq)^(PFOS) and K_(Eq)^(PFOA). These results suggest enhanced sonochemical degradation rates for PFOX when the bubble interface is undersaturated. The present results are compared to previously reported sonochemical kinetics of nonvolatile surfactants
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