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Time-series characteristics of UK commercial property returns: testing for multiple changes in persistence
The random-walk hypothesis, vis-Ă -vis asset prices , suggests that prices traded in a market cannot be predicted based on historical information. Employing unsecuritised UK commercial property returns, we analyze this hypothesis, investigating multiple changes in persistence in the series . Our results uncover multiple changes in persistence in both the aggregate and sector-specific data. We highlight some implications for academics, practitioners and regulators
R-Parity Violating Supersymmetry Explanation for Large t tbar Forward-Backward Asymmetry
We propose a supersymmetric explanation for the anomalously high forward
backward asymmetry in top pair production measured by CDF and D0. We suppose
that it is due to the t-channel exchange of a right-handed sbottom which
couples to d_R and t_R, as is present in the R-parity violating minimal
supersymmetric standard model. We show that all Tevatron and LHC experiments' t
tbar constraints may be respected for a sbottom mass between 300 and 1200 GeV,
and a large Yukawa coupling >2.2, yielding A_{FB} up to 0.18. The non Standard
Model contribution to the LHC charge asymmetry parameter is Delta
A_C^y=0.017-0.045, small enough to be consistent with current measurements but
non-zero and positive, allowing for LHC confirmation in the future within 20
fb^-1. A small additional contribution to the LHC t tbar production
cross-section is also predicted, allowing a further test. We estimate that 10
fb^-1 of LHC luminosity would be sufficient to rule out the proposal to 95%
confidence level, if the measurements of the t tbar cross-section turn out to
be centred on the Standard Model prediction.Comment: 5 pages, 2 figures, v2 has added comments and references and
increased statistics, leading to more accurate numerical predictions. v3 has
typos in Fig 1 fixed: arrow directions and t and tbar labels. v4 has added
discussion and corrections to Eq 4. v5 has luminosity predictions, additional
checks and small numerical change
Supersymmetry without a light Higgs boson at the LHC
We analyze the LHC phenomenology of lambdaSUSY - a version of NMSSM with a
largish SH1H2 coupling. The scalar spectrum of the model contains a 200-300 GeV
Higgs boson h with Standard-Model like properties, and heavy CP-even and CP-odd
Higgs bosons H and A with masses in 500-800 GeV range. We study the discovery
potential of H and A in the decay chains H->hh->4V->2l6j and A->Zh->Z2V->2l4j.
The dominant backgrounds are the diffuse Z6j and Z4j productions, which can be
suppressed by demanding reconstruction of V's and h's in intermediate states.
The excess of signal events allows for a discovery of both H and A with over
5sigma significance for 100 inverse fb of integrated luminosity.Comment: 29 pages, 19 figure
Quark mixing renormalization effects in the determination of |V_{tq}|
We study the numerical effects of several renormalization schemes of the
Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix on the top-quark decay
widths. We then employ these results to infer the relative shifts in the CKM
parameters |V_{tq}|^2 due to the quark mixing renormalization corrections,
assuming that they are determined directly from the top-quark partial decay
widths, without imposing unitarity constraints. We also discuss the
implications of these effects on the ratio R = Gamma(t -> Wb) / Gamma_t and the
determination of |V_{tb}|^2.Comment: 10 pages, 3 table
Top quark physics at the Tevatron
In this paper I summarize some of the most recent top quark physics results obtained by the CDF and D0 Collaborations, analysing data collected during Run II of the Tevatron Collider. The top pair production cross section has been
measured with a precision comparable to the theoretical one (5.4%). A precision of 0.5% on the measurement of the top quark mass has been achieved. The single top production in the s channel has been measured. The top quark production
mechanism, decay vertex and kinematic distributions have been investigated to test many aspects of the Standard Model. Most of the results shown here are already based on the full Run II dataset
The use of new technologies in advanced Italian classes
This paper discusses the results of a blended learning strategy which has recently been adopted in advanced Italian classes at the University of Wollongong. The embracing of new technologies in education has engendered a deep innovation in teaching and learning processes. Language learning, in particular, seems to have been more receptive than other fields thanks to the dynamics which characterize the subject and to the communicative approach currently used. However, if the information and communication technology curriculum integration offers powerful tools to enhance language learning, in terms of greater emphasis upon flexibility, transferability, individualisation, modularisation, mobility and interaction, it also creates critical points which require an attentive evaluation to make the impact on teaching and learning significant
Top quark studies at the Tevatron
A selection of the most recent CDF and D0 results in the top quark sector is presented. The top quark pair production and single top production and cross section measurements are discussed. The tÂŻt charge asymmetry results are shown. The most recent top quark mass measurements and the Tevatron combined top quark mass are illustrated
A three-dimensional model for the radio emission of magnetic chemically peculiar stars
In this paper we present a three-dimensional numerical model for the radio
emission of Magnetic Chemically Peculiar stars, on the hypothesis that
energetic electrons emit by the gyrosynchrotron mechanism. For this class of
radio stars, characterized by a mainly dipolar magnetic field whose axis is
tilted with respect to the rotational axis, the geometry of the magnetosphere
and its deformation due to the stellar rotation are determined. The radio
emitting region is determined by the physical conditions of the magnetosphere
and of the stellar wind. Free-free absorption by the thermal plasma trapped in
the inner magnetosphere is also considered. Several free parameters are
involved in the model, such as the size of the emitting region, the energy
spectrum and the number density of the emitting electrons, and the
characteristics of the plasma in the inner magnetosphere. By solving the
equation of radiative transfer, along a path parallel to the line of sight, the
radio brightness distribution and the total flux density as a function of
stellar rotation are computed. As the model is applied to simulate the observed
5 GHz lightcurves of HD37479 and HD37017, several possible magnetosphere
configurations are found. After simulations at other frequencies, in spite of
the large number of parameters involved in the modeling, two solutions in the
case of HD37479 and only one solution in the case of HD37017 match the observed
spectral indices. The results of our simulations agree with the magnetically
confined wind-shock model in a rotating magnetosphere. The X-ray emission from
the inner magnetosphere is also computed, and found to be consistent with the
observations.Comment: 15 pages, 10 figures, A&A in pres
Optical properties of Ge-oxygen defect center embedded in silica films
The photo-luminescence features of Ge-oxygen defect centers in a 100nm thick
Ge-doped silica film on a pure silica substrate were investigated by looking at
the emission spectra and time decay detected under synchrotron radiation
excitation in the 10-300 K temperature range. This center exhibits two
luminescence bands centered at 4.3eV and 3.2eV associated with its
de-excitation from singlet (S1) and triplet (T1) states, respectively, that are
linked by an intersystem crossing process. The comparison with results obtained
from a bulk Ge-doped silica sample evidences that the efficiency of the
intersystem crossing rate depends on the properties of the matrix embedding the
Ge-oxygen defect centers, being more effective in the film than in the bulk
counterpart.Comment: 10 pages, 3 figures, in press on J. Non cryst. solids (2007
Bell inequality violation by entangled single photon states generated from a laser, a LED or a Halogen lamp
In single-particle or intraparticle entanglement, two degrees of freedom of a
single particle, e.g., momentum and polarization of a single photon, are
entangled. Single-particle entanglement (SPE) provides a source of non
classical correlations which can be exploited both in quantum communication
protocols and in experimental tests of noncontextuality based on the
Kochen-Specker theorem. Furthermore, SPE is robust under decoherence phenomena.
Here, we show that single-particle entangled states of single photons can be
produced from attenuated sources of light, even classical ones. To
experimentally certify the entanglement, we perform a Bell test, observing a
violation of the Clauser, Horne, Shimony and Holt (CHSH) inequality. On the one
hand, we show that this entanglement can be achieved even in a classical light
beam, provided that first-order coherence is maintained between the degrees of
freedom involved in the entanglement. On the other hand, we prove that filtered
and attenuated light sources provide a flux of independent SPE photons that,
from a statistical point of view, are indistinguishable from those generated by
a single photon source. This has important consequences, since it demonstrates
that cheap, compact, and low power entangled photon sources can be used for a
range of quantum technology applications
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