76,176 research outputs found
Measure of multipartite entanglement with computable lower bounds
In this paper, we present a measure of multipartite entanglement
(-nonseparable), -ME concurrence that
unambiguously detects all -nonseparable states in arbitrary dimensions,
where the special case, 2-ME concurrence , is a
measure of genuine multipartite entanglement. The new measure -ME
concurrence satisfies important characteristics of an entanglement measure
including entanglement monotone, vanishing on -separable states, convexity,
subadditivity and strictly greater than zero for all -nonseparable states.
Two powerful lower bounds on this measure are given. These lower bounds are
experimentally implementable without quantum state tomography and are easily
computable as no optimization or eigenvalue evaluation is needed. We illustrate
detailed examples in which the given bounds perform better than other known
detection criteria.Comment: 12 pages, 3 figure
Heavy Quarkonium
I review heavy quarkonium physics in view of recent experimental results. In
particular, I discuss new results on spin singlet states, photon and hadronic
transitions, D-states and discovery of yet unexplained narrow X(3872) state.Comment: 15 pages, 16 figures. 2nd version: minor changes in references and
text. Invited talk presented at the 21st International Symposium On Lepton
And Photon Interactions At High Energies (LP03) 11-16 August 2003, Batavia,
Illinoi
Intrinsic Anomalous Hall Effect in Magneto-Chiral States
We show that a finite Hall effect in zero applied magnetic field occurs for
partially filled bands in certain time-reversal violating states with zero net
flux per unit-cell. These states are the Magneto-chiral states with parameters
in the effective one-particle Hamiltonian such that they do not satisfy the
Haldane-type constraints for topological electronic states. The results extend
an earlier discussion of the Kerr effect observed in the cuprates but may be
applicable to other experimental situations.Comment: published versio
The ALPINE-ALMA [C II] survey: Star-formation-driven outflows and circumgalactic enrichment in the early Universe
We study the efficiency of galactic feedback in the early Universe by stacking the [C II] 158 μm emission in a large sample of normal star-forming galaxies at 4 4. From the stacking analysis of the datacubes, we find that the combined [C II] core emission (|v|< 200 km s⁻¹) of the higher-SFR galaxies is extended on physical sizes of ∼30 kpc (diameter scale), well beyond the analogous [C II] core emission of lower-SFR galaxies and the stacked far-infrared continuum. The detection of such extended metal-enriched gas, likely tracing circumgalactic gas enriched by past outflows, corroborates previous similar studies, confirming that baryon cycle and gas exchanges with the circumgalactic medium are at work in normal star-forming galaxies already at early epochs
|V_ub| and |V_cb|, Charm Counting and Lifetime Differences in Inclusive Bottom Hadron Decays
Inclusive bottom hadron decays are analyzed based on the heavy quark
effective field theory (HQEFT). Special attentions in this paper are paid to
the b\to u transitions and nonspectator effects. As a consequence, the CKM
quark mixing matrix elements |V_ub| and |V_cb| are reliably extracted from the
inclusive semileptonic decays B\to X_u e \nu and B\to X_c e \nu. Various
observables, such as the semileptonic branch ratio B_SL, the lifetime
differences among B^-, B^0, B_s and \Lambda_b hadrons, the charm counting n_c,
are predicted and found to be consistent with the present experimental data.Comment: 20 pages, Revtex, 4 figures and 2 table
Electron beam profile imaging in the presence of coherent optical radiation effects
High-brightness electron beams with low energy spread at existing and future
x-ray free-electron lasers are affected by various collective beam
self-interactions and microbunching instabilities. The corresponding coherent
optical radiation effects, e.g., coherent optical transition radiation, render
electron beam profile imaging impossible and become a serious issue for all
kinds of electron beam diagnostics using imaging screens. Furthermore, coherent
optical radiation effects can also be related to intrinsically ultrashort
electron bunches or the existence of ultrashort spikes inside the electron
bunches. In this paper, we discuss methods to suppress coherent optical
radiation effects both by electron beam profile imaging in dispersive beamlines
and by using scintillation imaging screens in combination with separation
techniques. The suppression of coherent optical emission in dispersive
beamlines is shown by analytical calculations, numerical simulations, and
measurements. Transverse and longitudinal electron beam profile measurements in
the presence of coherent optical radiation effects in non-dispersive beamlines
are demonstrated by applying a temporal separation technique.Comment: 12 pages, 11 figures, submitted to Phys. Rev. ST Accel. Beam
A magnetized torus for modeling Sgr A* millimeter images and spectra
Context. The supermassive black hole, Sagittarius (Sgr) A*, in the centre of
our Galaxy has the largest angular size in the sky among all astrophysical
black holes. Its shadow, assuming no rotation, spans ~ 50 microarcsec.
Resolving such dimensions has long been out of reach for astronomical
instruments until a new generation of interferometers being operational during
this decade. Of particular interest is the Event Horizon Telescope (EHT) with
resolution ~ 20 microarcsec in the millimeter-wavelength range 0.87 mm - 1.3
mm. Aims. We investigate the ability of the fully general relativistic
Komissarov (2006) analytical magnetized torus model to account for observable
constraints at Sgr A* in the centimeter and millimeter domains. The impact of
the magnetic field geometry on the observables is also studied. Methods. We
calculate ray-traced centimeter- and millimeter-wavelength synchrotron spectra
and images of a magnetized accretion torus surrounding the central black hole
in Sgr A*. We assume stationarity, axial symmetry, constant specific angular
momentum and polytropic equation of state. A hybrid population of thermal and
non-thermal electrons is considered. Results. We show that the torus model is
capable of reproducing spectral constraints in the millimeter domain, and in
particular in the observable domain of the EHT. However, the torus model is not
yet able to fit the centimeter spectrum. 1.3 mm images at high inclinations are
in agreement with observable constraints. Conclusions. The ability of the torus
model to account for observations of Sgr A* in the millimeter domain is
interesting in the perspective of the future EHT. Such an analytical model
allows very fast computations. It will thus be a suitable test bed for
investigating large domains of physical parameters, as well as non-black-hole
compact object candidates and alternative theories of gravity.Comment: Major changes wrt the June 2014 version. Accepted by A&
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