Electromagnetic Transition Form Factors of Mesons

Using a counting scheme which treats pseudoscalar and vector mesons on equal footing, the decays of the narrow light vector mesons omega and phi into a dilepton and a pseudoscalar pi-meson or eta-meson, respectively, are calculated. Thereby, all required parameters could be determined by other reactions so that one has predictive power for the considered decays. The calculated partial decay widths are in very good agreement with the experimental data.Comment: Talk given at the 33rd International School of Nuclear Physics (From Quarks and Gluons to Hadrons and Nuclei) in Erice (Italy

The RHIC Zero Degree Calorimeter

High Energy collisions of nuclei usually lead to the emission of evaporation neutrons from both ``beam'' and ``target'' nuclei. At the RHIC heavy ion collider with 100GeV/u beam energy, evaporation neutrons diverge by less than $~2$ milliradians from the beam axis Neutral beam fragments can be detected downstream of RHIC ion collisions (and a large aperture Accelerator dipole magnet) if $\theta\leq$ 4 mr but charged fragments in the same angular range are usually too close to the beam trajectory. In this 'zero degree' region produced particles and other secondaries deposit negligible energy when compared with that of beam fragmentation neutrons. The purpose of the RHIC zero degree calorimeters (ZDC's) is to detect neutrons emitted within this cone along both beam directions and measure their total energy (from which we calculate multiplicity). The ZDC coincidence of the 2 beam directions is a minimal bias selection of heavy ion collisions. This makes it useful as an event trigger and a luminosity monitor\cite{baltz} and for this reason we built identical detectors for all 4 RHIC experiments. The neutron multiplicity is also known to be correlated with event geometry \cite{appel} and will be used to measure collision centrality in mutual beam int eractions.Comment: 18 pages, 12 figure

Study of the electromagnetic transition form-factors in \eta -> \mu^+\mu^-\gamma and \omega -> \mu^+\mu^-\pi^0 decays with NA60

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158A GeV In-In collisions. The mass and pT spectra associated with peripheral collisions can quantitatively be described by the known neutral meson decays. The high data quality has allowed to remeasure the electromagnetic transition form factors of the Dalitz decays \eta -> \mu^+\mu^-\gamma and \omega -> \mu^+\mu^-\pi^0. Using the usual pole approximation F = (1-M_{\mu\mu}^{2}/\Lambda^{2})^{-1} for the form factors, we find \Lambda^{-2} (in GeV^{-2}) to be 1.95+-0.17(stat.)+-0.05(syst.) for the \eta and 2.24+-0.06(stat.)+-0.02(syst.) for the \omega. While the values agree with previous results from the Lepton-G experiment, the errors are greatly improved, confirming now on the level of 10\sigma the strong enhancement of the \omega form factor beyond the expectation from vector meson dominance. An improved value of the branching ratio BR(\omega -> \mu^+\mu^-\pi^0) = [1.73+-0.25(stat.)+-0.14(syst.)]*10^{-4} has been obtained as a byproduct.Comment: Submitted to Phys. Lett.

Spin physics at A Fixed-Target ExpeRiment at the LHC (AFTER@LHC)

We outline the opportunities for spin physics which are offered by a next generation and multi-purpose fixed-target experiment exploiting the proton LHC beam extracted by a bent crystal. In particular, we focus on the study of single transverse spin asymetries with the polarisation of the target.Comment: Contributed to the 20th International Spin Physics Symposium, SPIN2012, 17-22 September 2012, Dubna, Russia, 4 pages, LaTe

Prospectives for A Fixed-Target ExpeRiment at the LHC: AFTER@LHC

We argue that the concept of a multi-purpose fixed-target experiment with the proton or lead-ion LHC beams extracted by a bent crystal would offer a number of ground-breaking precision-physics opportunities. The multi-TeV LHC beams will allow for the most energetic fixed-target experiments ever performed. The fixed-target mode has the advantage of allowing for high luminosities, spin measurements with a polarised target, and access over the full backward rapidity domain --uncharted until now-- up to x_F ~ -1.Comment: 6 pages, 1 table, LaTeX. Proceedings of the 36th International Conference on High Energy Physics (ICHEP2012), 4-11 July 2012, Melbourne, Australi

A Fixed-Target ExpeRiment at the LHC (AFTER@LHC) : luminosities, target polarisation and a selection of physics studies

We report on a future multi-purpose fixed-target experiment with the proton or lead ion LHC beams extracted by a bent crystal. The multi-TeV LHC beams allow for the most energetic fixed-target experiments ever performed. Such an experiment, tentatively named AFTER for "A Fixed-Target ExperRiment", gives access to new domains of particle and nuclear physics complementing that of collider experiments, in particular at RHIC and at the EIC projects. The instantaneous luminosity at AFTER using typical targets surpasses that of RHIC by more than 3 orders of magnitude. Beam extraction by a bent crystal offers an ideal way to obtain a clean and very collimated high-energy beam, without decreasing the performance of the LHC. The fixed-target mode also has the advantage of allowing for spin measurements with a polarised target and for an access over the full backward rapidity domain up to xF ~ - 1. Here, we elaborate on the reachable luminosities, the target polarisation and a selection of measurements with hydrogen and deuterium targets.Comment: 6 pages. Proceedings of the Sixth International Conference on Quarks and Nuclear Physics QNP2012 (16-20 April 2012, Ecole Polytechnique, Palaiseau,France

Electromagnetic Probes

A review is presented of dilepton and real photon measurements in relativistic heavy ion collisions over a very broad energy range from the low energies of the BEVALAC up to the highest energies available at RHIC. The dileptons cover the invariant mass range \mll = 0 - 2.5 GeV/c$^2$, i.e. the continuum at low and intermediate masses and the light vector mesons, $\rho, \omega, \phi$. The review includes also measurements of the light vector mesons in elementary reactions.Comment: To be published in Landolt-Boernstein Volume 1-23A; 40 pages, 24 figures. Final version updated with small changes to the text, updated references and updated figure

Recent Heavy-Flavor results at STAR

We present the recent results on non-photonic electron (NPE) yields from RHIC run8 p+p collisions. The $e/\pi$ ratio as a function of $p_T$ in run8 with a factor of 10 reduction of the inner detector material at STAR is found to be consistent with those results from run3 taking into account the NPE from charm leptonic decay and the difference of photonic electron yield from photon conversion in detector material. \Jpsi spectra in \pp and \cucu collisions at \sNN = 200 GeV with high sampled luminosity \Jpsi spectrum at high-\pT follows $x_T$ scaling, but the scaling is violated at low \pT. $J/\psi$-hadron correlations in \pp collisions are studied to understand the \Jpsi production mechanism at high $p_T$. We observed an absence of charged hadrons accompanying \Jpsi on the near-side, in contrast to the strong correlation peak in the di-hadron correlations. This constrains the $B$-meson contribution and jet fragmentation to inclusive \Jpsi to be ${}^{<}_{\sim}17$. Yields in minimum-bias \cucu collisions are consistent with those in \pp collisions scaled by the underlying binary nucleon-nucleon collisions in the measured \pT range. Other measurements and future projects related to heavy-flavors are discussed.Comment: 8 pages 4 figures, proceedings of the International Conference on Strangeness in Quark Matter 2008 - Beijing, China, Oct. 6-10, 200

Comparative study of MRI biomarkers in the substantia nigra to discriminate idiopathic Parkinson disease

BACKGROUND AND PURPOSE: Several new MR imaging techniques have shown promising results in patients with Parkinson disease; however, the comparative diagnostic values of these measures at the individual level remain unclear. Our aim was to compare the diagnostic value of MR imaging biomarkers of substantia nigra damage for distinguishing patients with Parkinson disease from healthy volunteers. MATERIALS AND METHODS: Thirty-six patients and 20 healthy volunteers were prospectively included. The MR imaging protocol at 3T included 3D T2-weighted and T1-weighted neuromelanin-sensitive images, diffusion tensor images, and R2* mapping. T2* high-resolution images were also acquired at 7T to evaluate the dorsal nigral hyperintensity sign. Quantitative analysis was performed using ROIs in the substantia nigra drawn manually around the area of high signal intensity on neuromelanin-sensitive images and T2-weighted images. Visual analysis of the substantia nigra neuromelanin-sensitive signal intensity and the dorsolateral nigral hyperintensity on T2* images was performed. RESULTS: There was a significant decrease in the neuromelanin-sensitive volume and signal intensity in patients with Parkinson disease. There was also a significant decrease in fractional anisotropy and an increase in mean, axial, and radial diffusivity in the neuromelanin-sensitive substantia nigra at 3T and a decrease in substantia nigra volume on T2* images. The combination of substantia nigra volume, signal intensity, and fractional anisotropy in the neuromelanin-sensitive substantia nigra allowed excellent diagnostic accuracy (0.93). Visual assessment of both substantia nigra dorsolateral hyperintensity and neuromelanin-sensitive images had good diagnostic accuracy (0.91 and 0.86, respectively). CONCLUSIONS: The combination of neuromelanin signal and volume changes with fractional anisotropy measurements in the substantia nigra showed excellent diagnostic accuracy. Moreover, the high diagnostic accuracy of visual assessment of substantia nigra changes using dorsolateral hyperintensity analysis or neuromelanin-sensitive signal changes indicates that these techniques are promising for clinical practice

The degree of urinary hypercortisolism is not correlated with the severity of cushing’s syndrome

Cushing syndrome (CS) is characterized by increased morbidity and mortality compared to the general population. However, there are patients who have moreclinical aggressive forms than others. Aim of the study is to evaluate whether the degree of hypercortisolism, defined by the number of times urinary free cortisol (UFC) levels exceed the upper limit of the normal range (ULN), is related to the worsening of phenotypic features, as well as metabolic and cardiovascular parameters, in a cohort of CS patients. A cross-sectional study was conducted on 192 patients with active CS, consecutively presenting at the outpatients’ clinic of the University Hospitals of Ancona, Naples, and Palermo. Patients were grouped into mild (UFC not exceeding twice the ULN), moderate (2–5 times the ULN), and severe (more than 5 times the ULN) hypercortisolism. Thirty-seven patients (19.3 %) had mild, 115 (59.8 %) moderate, and 40 (20.9 %) severe hypercortisolism. A significant trend of increase among the three groups was demonstrated for 8-, 16-, and 24-h serum cortisol levels (p.001) and serum cortisol after low dose of dexamethasone suppression test (p = 0.001). No significant trend of increase was found regarding phenotype and comorbidities. The degree of hypercortisolism by itself does not appear to be a sufficient parameter to express the severity of CS. Therefore, estimating the severity of CS according to biochemical parameters remains a challenge, while the clinical phenotype and the associated comorbidities might be more useful to assessing the severity of the CS