Holographic model for heavy vector meson masses

The experimentally observed spectra of heavy vector meson radial excitations show a dependence on two different energy parameters. One is associated with the quark mass and the other with the binding energy levels of the quark anti-quark pair. The first is present in the large mass of the first state while the other corresponds to the small mass splittings between radial excitations. In this article we show how to reproduce such a behavior with reasonable precision using a holographic model. In the dual picture, the large energy scale shows up from a bulk mass and the small scale comes from the position of anti-de Sitter (AdS) space where field correlators are calculated. The model determines the masses of four observed S-wave states of charmonium and six S-wave states of bottomonium with , 6.1 % rms error. In consistency with the physical picture, the large energy parameter is flavor dependent, while the small parameter, associated with quark anti-quark interaction is the same for charmonium and bottomonium states.Comment: In V5 we just added some clarifying explanations about the model. 5 tables, no figure. Version published in Europhysics Letter

Holographic Picture of Heavy Vector Meson Melting

The fraction of heavy vector mesons produced in a heavy ion collision, as compared to a proton proton collision, serves as an important indication of the formation of a thermal medium, the quark gluon plasma. This sort of analysis strongly depends on understanding the thermal effects of a medium like the plasma on the states of heavy mesons. In particular, it is crucial to know the temperature ranges where they undergo a thermal dissociation, or melting. AdS/QCD models are know to provide an important tool for the calculation of hadronic masses, but in general are not consistent with the observation that decay constants of heavy vector mesons decrease with excitation level. It has recently been shown that this problem can be overcome using a soft wall background and introducing an extra energy parameter, through the calculation of correlation functions at a finite position of anti-de Sitter space. This approach leads to the evaluation of masses and decay constants of S wave quarkonium states with just one flavor dependent and one flavor independent parameters. Here we extend this more realistic model to finite temperatures and analyse the thermal behavior of the states $1S, 2S$ and $3S$ of bottomonium and charmonium. The corresponding spectral function exhibits a consistent picture for the melting of the states where, for each flavor, the higher excitations melt at lower temperatures. We estimate for these six states, the energy ranges in which the heavy vector mesons undergo a transition from a well defined peak in the spectral function to complete melting in the thermal medium. A very clear distinction between the heavy flavors emerges, with bottomonium state $\Upsilon (1S)$ surviving deconfinemet transition at temperatures much larger than the critical deconfinement temperature of the medium.Comment: 20 pages, 7 figure

Superspace Formulation for the BRST Quantization of the Chiral Schwinger Model

It has recently been shown that the Field Antifield quantization of anomalous irreducible gauge theories with closed algebra can be represented in a BRST superspace where the quantum action at one loop order, including the Wess Zumino term, and the anomalies show up as components of the same superfield. We show here how the Chiral Schwinger model can be represented in this formulation.Comment: 11 pages, Late

Telescope performance and image simulations of the balloon-borne coded-mask protoMIRAX experiment

In this work we present the results of imaging simulations performed with the help of the GEANT4 package for the protoMIRAX hard X-ray balloon experiment. The instrumental background was simulated taking into account the various radiation components and their angular dependence, as well as a detailed mass model of the experiment. We modeled the meridian transits of the Crab Nebula and the Galatic Centre region during balloon flights in Brazil ($\sim -23^{\circ}$ of latitude and an altitude of $\sim 40 \thinspace$ km) and introduced the correspondent spectra as inputs to the imaging simulations. We present images of the Crab and of three sources in the Galactic Centre region: 1E 1740.7-2942, GRS 1758-258 and GX 1+4. The results show that the protoMIRAX experiment is capable of making spectral and timing observations of bright hard X-ray sources as well as important imaging demonstrations that will contribute to the design of the MIRAX satellite mission.Comment: 9 figure

Decay constants in soft wall AdS/QCD revisited

Phenomenological AdS/QCD models, like hard wall and soft wall, provide hadronic mass spectra in reasonable consistency with experimental and (or) lattice results. These simple models are inspired in the AdS/CFT correspondence and assume that gauge/ gravity duality holds in a scenario where conformal invariance is broken through the introduction of an energy scale. Another important property of hadrons: the decay constant, can also be obtained from these models. However, a consistent formulation of an AdS/QCD model that reproduces the observed behavior of decay constants of vector meson excited states is still lacking. In particular: for radially excited states of heavy vector mesons, the experimental data lead to decay constants that decrease with the radial excitation level. We show here that a modified framework of soft wall AdS/QCD involving an additional dimensionfull parameter, associated with an ultraviolet energy scale, provides decay constants decreasing with radial excitation level. In this version of the soft wall model the two point function of gauge theory operators is calculated at a finite position of the anti-de Sitter space radial coordinate.Comment: Shorter (letter) version. Results unchanged. More references included. We now explain that the large UV scale of the model is associated with the non-hadronic decay of the heavy vector meson into light leptons. Version Published in Phys. Lets.

The utility of measurement uncertainty in medical laboratories

Abstract: The definition and enforcement of reference measurement systems, based on the implementation of metrological traceability of patient results to higherorder (reference) methods and/or materials, together with a clinically acceptable level of measurement uncertainty (MU), are fundamental requirements to produce accurate and equivalent laboratory results. The MU associated with each step of the traceability chain should be governed to obtain a final combined MU on clinical samples fulfilling the requested performance specifications. MU is useful for a number of reasons: (a) for giving objective information about the quality of individual laboratory performance; (b) for serving as a management tool for the medical laboratory and in vitro diagnostics (IVD) manufacturers, forcing them to investigate and eventually fix the identified problems; (c) for helping those manufacturers that produce superior products and measuring systems to demonstrate the superiority of those products; (d) for identifying analytes that need analytical improvement for their clinical use and ask IVD manufacturers to work for improving the quality of assay performance and (e) for abandoning assays with demonstrated insufficient quality. Accordingly, the MU should not be considered a parameter to be calculated by medical laboratories just to fulfill accreditation standards, but it must become a key quality indicator to describe both the performance of an IVD measuring system and the laboratory itself

Confirming the thermal Comptonization model for black hole X-ray emission in the low-hard state

Hard X-ray spectra of black hole binaries in the low/hard state are well modeled by thermal Comptonization of soft seed photons by a corona-type region with $kT$\thinspace$\sim 50${\thinspace}keV and optical depth around 1. Previous spectral studies of 1E{\thinspace}1740.7$-$2942, including both the soft and the hard X-ray bands, were always limited by gaps in the spectra or by a combination of observations with imaging and non-imaging instruments. In this study, we have used three rare nearly-simultaneous observations of 1E{\thinspace}1740.7$-$1942 by both XMM-Newton and INTEGRAL satellites to combine spectra from four different imaging instruments with no data gaps, and we successfully applied the Comptonization scenario to explain the broadband X-ray spectra of this source in the low/hard state. For two of the three observations, our analysis also shows that, models including Compton reflection can adequately fit the data, in agreement with previous reports. We show that the observations can also be modeled by a more detailed Comptonization scheme. Furthermore, we find the presence of an iron K-edge absorption feature in one occasion, which confirms what had been previously observed by Suzaku. Our broadband analysis of this limited sample shows a rich spectral variability in 1E{\thinspace}1740.7$-$2942 at the low/hard state, and we address the possible causes of these variations. More simultaneous soft/hard X-ray observations of this system and other black-hole binaries would be very helpful in constraining the Comptonization scenario and shedding more light on the physics of these systems.Comment: 6 pages, two figures, accepted for publication in A&

Axial Anomaly from the BPHZ regularized BV master equation

A BPHZ renormalized form for the master equation of the field antifiled (or BV) quantization has recently been proposed by De Jonghe, Paris and Troost. This framework was shown to be very powerful in calculating gauge anomalies. We show here that this equation can also be applied in order to calculate a global anomaly (anomalous divergence of a classically conserved Noether current), considering the case of QED. This way, the fundamental result about the anomalous contribution to the Axial Ward identity in standard QED (where there is no gauge anomaly) is reproduced in this BPHZ regularized BV framework.Comment: 10 pages, Latex, minor changes in the reference