Photoimagen, an event and now a centre for images

La fundación Imagen 83 creada por Mayra Johnson celebra el festival de fotografía Photoimagen y nos cuenta la experiencia de exposiciones y eventos paralelos al mism

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Photoimagen. Un evento y ahora un centro de la imagen

La fundación Imagen 83 creada por Mayra Johnson celebra el festival de fotografía Photoimagen y nos cuenta la experiencia de exposiciones y eventos paralelos al mismo. Palabras clave: fotografía, patrimonio documental, educación y ocio, actividad cultural. Photoimagen, an event and now a centre for images Abstract: Fundación Imagen 83, which was created by Mayra Johnson, hosts the Photoimagen photography festival. This paper relates the experience of the exhibition and events held in parallel to it. Keywords: photography, documentary heritage, education and leisure, cultural activity. Artículo recibido: 08/10/2009. Aceptado: 26/10/200

Precision of single-qubit gates based on Raman transitions

We analyze the achievable precision for single-qubit gates that are based on Raman transitions between two near-degenerate ground states via a virtually excited state. In particular, we study the errors due to non-perfect adiabaticity and due to spontaneous emission from the excited state. For the case of non-adabaticity, we calculate the error as a function of the dimensionless parameter $\chi=\Delta \tau$, where $\Delta$ is the detuning of the Raman beams and $\tau$ is the gate time. For the case of spontaneous emission, we give an analytical argument that the gate errors are approximately equal to $\Lambda \gamma/\Delta$, where $\Lambda$ is the rotation angle of the one-qubit gate and $\gamma$ is the spontaneous decay rate, and we show numerically that this estimate holds to good approximation.Comment: 8 pages, 10 figure

Quarkonia and heavy flavors at the LHC

Perspectives for quarkonia and heavy flavors measurements in heavy ion collisions at LHC are reviewedComment: 6 pages, Proceedings of the Hard Probes 2004 Conference, Ericeira, Portugal, Nov 2004, replaced with revised versio

Bragg spectroscopy of discrete axial quasiparticle modes in a cigar-shaped degenerate Bose gas

We propose an experiment in which long wavelength discrete axial quasiparticle modes can be imprinted in a 3D cigar-shaped Bose-Einstein condensate by using two-photon Bragg scattering experiments, similar to the experiment at the Weizmann Institute [J. Steinhauer {\em et al.}, Phys. Rev. Lett. {\bf 90}, 060404 (2003)] where short wavelength axial phonons with different number of radial modes have been observed. We provide values of the momentum, energy and time duration of the two-photon Bragg pulse and also the two-body interaction strength which are needed in the Bragg scattering experiments in order to observe the long wavelength discrete axial modes. These discrete axial modes can be observed when the system is dilute and the time duration of the Bragg pulse is long enough.Comment: 5 pages, 3 figures, title, abstract, results changed, references added. to appear in The European Physical Journal

Polarization observables in the processes p+p→Θ++Σ+p+p\to \Theta^+ +\Sigma^+ and n+p→Θ++Λ0n+p\to \Theta^+ +\Lambda^0, for any spin and parity of the Θ+\Theta^+-hyperon in the threshold region

Using the symmetry properties of the strong interaction, such as the Pauli principle, the P-invariance, the conservation of the total angular momentum and isotopic invariance, we establish the spin structure of the threshold matrix elements for the processes $p+p\to \Theta^+ +\Sigma^+$ and $n+p\to \Theta^+ +\Lambda^0$, in a model independent way, which applies to any spin and parity of the $\Theta^+$-hyperon in the near threshold region. We predict the double spin observables for these processes, such as the dependence of the differential cross section on the polarizations of the colliding nucleons, and the coefficients of polarization transfer from a nucleon beam or target to the produced $\Sigma^+$ or $\Lambda^0$ hyperon. We prove that these observables are sensitive to the P-parity of the $\Theta^+$ baryon, for any value of its spin. As an example of dynamical considerations, we analyzed these reactions in the framework of K-meson exchange.Comment: 14 pages 1 figur

New result on the measurement of the direct photon emission in K+ --> pi^+ pi^0 gamma decay

We present a new result on the K^+ --> pi^+ pi^0 gamma decay measurement using stopped kaons. The best fit to the decay spectrum comprised of 10k events gives a branching ratio for the direct photon emission of [3.8+-0.8(stat)+-0.7(syst)] times 10^{-6} in the pi^+ kinetic energy region of 55 to 90 MeV. This result has been obtained with the assumption that there is no component due to interference with the inner bremsstrahlung.Comment: 14 pages, 7 figures, 3 tables (Fig.1 which had problems with uploading first time is replaced. Besides introduction is changed to bring into accordance with the version published in Eur.Phys.J.C.