158 research outputs found
A search for the fourth SM family quarks at Tevatron
It is shown that the fourth standard model (SM) family quarks can be observed
at the Fermilab Tevatron if their anomalous interactions with known quarks have
sufficient strength.Comment: 7 pages, 2 tables, 4 figure
Little Higgs models and single top production at the LHC
We investigate the corrections of the littlest Higgs(LH) model and the SU(3)
simple group model to single top production at the CERN Large Hardon
Collider(LHC). We find that the new gauge bosons predicted by the
LH model can generate significant contributions to single top production via
the s-channel process. The correction terms for the tree-level couplings
coming from the SU(3) simple group model can give large contributions to the
cross sections of the t-channel single top production process. We expect that
the effects of the LH model and the SU(3) simple group model on single top
production can be detected at the LHC experiments.Comment: 17pages, 5 figures, discussions and references added, typos correcte
Bright solitons and soliton trains in a fermion-fermion mixture
We use a time-dependent dynamical mean-field-hydrodynamic model to predict
and study bright solitons in a degenerate fermion-fermion mixture in a
quasi-one-dimensional cigar-shaped geometry using variational and numerical
methods. Due to a strong Pauli-blocking repulsion among identical
spin-polarized fermions at short distances there cannot be bright solitons for
repulsive interspecies fermion-fermion interactions. However, stable bright
solitons can be formed for a sufficiently attractive interspecies interaction.
We perform a numerical stability analysis of these solitons and also
demonstrate the formation of soliton trains. These fermionic solitons can be
formed and studied in laboratory with present technology.Comment: 5 pages, 7 figure
Dirac Spinors and Flavor Oscillations
In the standard treatment of particle oscillations the mass eigenstates are
implicitly assumed to be scalars and, consequently, the spinorial form of
neutrino wave functions is not included in the calculations. To analyze this
additional effect, we discuss the oscillation probability formula obtained by
using the Dirac equation as evolution equation for the neutrino mass
eigenstates. The initial localization of the spinor state also implies an
interference between positive and negative energy components of mass eigenstate
wave packets which modifies the standard oscillation probability.Comment: 14 pages, 1 figure, AMS-Te
Robust and fragile Werner states in the collective dephasing
We investigate the concurrence and Bell violation of the standard Werner
state or Werner-like states in the presence of collective dephasing. It is
shown that the standard Werner state and certain kinds of Werner-like states
are robust against the collective dephasing, and some kinds of Werner-like
states is fragile and becomes completely disentangled in a finite-time. The
threshold time of complete disentanglement of the fragile Werner-like states is
given. The influence of external driving field on the finite-time
disentanglement of the standard Werner state or Werner-like states is
discussed. Furthermore, we present a simple method to control the stationary
state entanglement and Bell violation of two qubits. Finally, we show that the
theoretical calculations of fidelity based on the initial Werner state
assumption well agree with previous experimental results.Comment: 7 pages, 6 figures, 1 table, RevTex4, Accepted by EPJ
Electric and magnetic form factors of strange baryons
Predictions for the electromagnetic form factors of the Lambda$, Sigma and Xi
hyperons are presented. The numerical calculations are performed within the
framework of the fully relativistic constituent-quark model developed by the
Bonn group. The computed magnetic moments compare favorably with the
experimentally known values. Most magnetic form factors G_M(Q^2) can be
parametrized in terms of a dipole with cutoff masses ranging from 0.79 to 1.14
GeV.Comment: 15 pages, 8 figures, 3 tables, submitted to Eur. Phys. J.
Near-threshold production of omega mesons in the pn -> d omega reaction
The first measurement of the p n -> d omega total cross section has been
achieved at mean excess energies of Q = 28 and 57 MeV by using a deuterium
cluster-jet target. The momentum of the fast deuteron was measured in the ANKE
spectrometer at COSY-Juelich and that of the slow "spectator" proton p(sp) from
the p d -> p(sp) d omega reaction in a silicon telescope placed close to the
target. The cross sections lie above those measured for p p -> p p omega but
seem to be below theoretical predictions.Comment: 7 pages, 8 figures; second approach to describe the background has
been added; results changed insignificantly, EPJ in pres
An Analysis of Decays Using a Global Fit in QCD Factorization
In the framework of QCD factorization, we study
decays. In order to more reliably determine the phenomenological parameters
and arising from end-point divergences in the hard spectator
scattering and weak annihilation contributions, we use the global analysis for
twelve and decay modes, such as , , , , etc, but excluding the modes whose (dominant) internal
quark-level process is . Based on the global analysis, we
critically investigate possible magnitudes of and find that both
large and small terms are allowed by the global fit. In the case of
the large effects, the standard model (SM) prediction of the
branching ratios (BRs) for is large and well
consistent with the experimental results. In contrast, in the case of the small
effects, the SM prediction for these BRs is smaller than the
experimental data. Motivated by the recent Belle measurement of through , if we take into account possible new
physics effects on the quark-level process , we can
explicitly show that these large BRs can be understood even in the small
case. Specifically, we present two new physics scenarios: R-parity
violating SUSY and R-parity conserving SUSY.Comment: 23 pages, 2 figures; Some references adde
Strange particle production in proton-proton collisions at TeV with ALICE at the LHC
The production of mesons containing strange quarks (K, ) and both
singly and doubly strange baryons (, Anti-, and
+Anti-) are measured at central rapidity in pp collisions at
= 0.9 TeV with the ALICE experiment at the LHC. The results are
obtained from the analysis of about 250 k minimum bias events recorded in 2009.
Measurements of yields (dN/dy) and transverse momentum spectra at central
rapidities for inelastic pp collisions are presented. For mesons, we report
yields () of 0.184 0.002 stat. 0.006 syst. for K and
0.021 0.004 stat. 0.003 syst. for . For baryons, we find
= 0.048 0.001 stat. 0.004 syst. for , 0.047
0.002 stat. 0.005 syst. for Anti- and 0.0101 0.0020 stat.
0.0009 syst. for +Anti-. The results are also compared with
predictions for identified particle spectra from QCD-inspired models and
provide a baseline for comparisons with both future pp measurements at higher
energies and heavy-ion collisions.Comment: 33 pages, 21 captioned figures, 10 tables, authors from page 28,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/387
Ageing and dementia in low and middle income countries - Using research to engage with public and policy makers
Abstract While two thirds of the 24 million people with dementia worldwide live in low and middle income countries, very little research has been conducted to support policy making in these regions. Among the non-communicable diseases, dementia (in common with other chronic NCDs linked more to long-term disability than to mortality) has been relatively under-prioritized. International agreements, plans and policy guidelines have called for an end to ageist discrimination and a focus upon reducing disadvantage arising from poverty and the consequences of ill health. Social protection, access to good quality age-appropriate healthcare and addressing the problem of disability are all key issues. However, as yet, little progress has been made in addressing these concerns. In this review we outline the current international policy agenda for older individuals, and its specific relevance to those with dementia and other disabling non-communicable diseases. We consider the potential for epidemiological research to raise awareness, refine the policy agenda, and promote action, using the example of the dissemination strategy developed by the 10/66 Dementia Research Group
- âŠ