Proton Form Factors And Related Processes in BaBar by ISR

BaBar has measured with unprecedented accuracy e{sup +}e{sup -} {yields} p{bar p} from the threshold up to Q{sub p{bar p}}{sup 2} {approx} 20 GeV{sup 2}/c{sup 4}, finding out an unexpected cross section, with plateaux and drops. In particular it is well established a sharp drop near threshold, where evidence for structures in multihadronic channels has also been found. Other unexpected and spectacular features of the Nucleon form factors are reminded, the behavior of space-like G{sub E}{sup p}/G{sub M}{sup p} and the neutron time-like form factors

Dilepton production in nucleus-nucleus collisions at top SPS energy within the Parton-Hadron-String Dynamics (PHSD) transport approach

Dilepton production in In+In collisions at 158 AGeV is studied within the microscopic parton-hadron-string dynamics (PHSD) transport approach that incorporates explicit partonic degrees-of-freedom, dynamical hadronization as well as the more familiar hadronic dynamics in the final reaction stages. A comparison to the data of the NA60 Collaboration shows that the measured dilepton yield is well described by including the collisional broadening of vector mesons, while simultaneously accounting for the electromagnetic radiation of the strongly coupled quark-gluon plasma (sQGP) via off-shell quark-antiquark annihilation, quark annihilation with additional gluon Bremsstrahlung and the gluon-Compton scattering mechanisms. In particular, the spectra in the intermediate mass range (1 GeV < M < 2.5 GeV) are dominated by quark-antiquark annihilation in the nonperturbative QGP. Also, the observed softening of the transverse mass spectra at intermediate masses (1 GeV < M < 2.5 GeV) is approximately reproduced. Furthermore, for dileptons of low masses (M < 0.6 GeV), we find a sizable contribution from the quark annihilation with additional gluon bremsstrahlung, thus providing another possible window for probing the properties of the sQGP.Comment: 16 pages, 14 figure

Higher excitations of ω\omega and ϕ\phi in dilepton spectra

We consider lepton pair production via two-hadron annihilation through various isoscalar vector mesons within hot, baryon-free matter. This is tantamount to constructing effective form factors which we model using a vector-meson-dominance approach and compare with experiment. In particular, we consider the reactions $\pi\rho\to e^+e^-$ and $\bar K K^{*}(892)$ + c.c. $\to e^+e^-$. We find that $\omega(1390)$ and $\phi(1680)$ are visible in the mass spectrum for the thermal production rate above the $\pi^{+}\pi^{-} \to e^+e^-$ tail and even above the $\pi a_{1}\to e^+e^-$ results---both of which were considered important in their respective mass regions.Comment: RevTeX, 9 pages, 6 (uuencoded) figures; to appear in Phys. Rev

The EEE Project

The new experiment ``Extreme Energy Events'' (EEE) to detect extensive air showers through muon detection is starting in Italy. The use of particle detectors based on Multigap Resistive Plate Chambers (MRPC) will allow to determine with a very high accuracy the direction of the axis of cosmic ray showers initiated by primaries of ultra-high energy, together with a high temporal resolution. The installation of many of such 'telescopes' in numerous High Schools scattered all over the Italian territory will also allow to investigate coincidences between multiple primaries producing distant showers. Here we present the experimental apparatus and its tasks.Comment: 4 pages, 29th ICRC 2005, Pune, Indi

First Ex-Vivo Validation of a Radioguided Surgery Technique with beta- Radiation

Purpose: A radio-guided surgery technique with beta- -emitting radio-tracers was suggested to overcome the effect of the large penetration of gamma radiation. The feasibility studies in the case of brain tumors and abdominal neuro-endocrine tumors were based on simulations starting from PET images with several underlying assumptions. This paper reports, as proof-of-principle of this technique, an ex-vivo test on a meningioma patient. This test allowed to validate the whole chain, from the evaluation of the SUV of the tumor, to the assumptions on the bio-distribution and the signal detection. Methods: A patient affected by meningioma was administered 300 MBq of 90Y-DOTATOC. Several samples extracted from the meningioma and the nearby Dura Mater were analyzed with a beta- probe designed specifically for this radio-guided surgery technique. The observed signals were compared both with the evaluation from the histology and with the Monte Carlo simulation. Results: we obtained a large signal on the bulk tumor (105 cps) and a significant signal on residuals of $\sim$0.2 ml (28 cps). We also show that simulations predict correctly the observed yields and this allows us to estimate that the healthy tissues would return negligible signals (~1 cps). This test also demonstrated that the exposure of the medical staff is negligible and that among the biological wastes only urine has a significant activity. Conclusions: This proof-of-principle test on a patient assessed that the technique is feasible with negligible background to medical personnel and confirmed that the expectations obtained with Monte Carlo simulations starting from diagnostic PET images are correct.Comment: 17 pages, 4 Figs, Accepted by Physica Medic

A model to explain angular distributions of J/ψJ/\psi and ψ(2S)\psi(2S) decays into ΛΛ‾\Lambda\overline{\Lambda} and Σ0Σ‾0\Sigma^0\overline{\Sigma}^0

BESIII data show a particular angular distribution for the decay of the $J/\psi$ and $\psi(2S)$ mesons into the hyperons $\Lambda\overline{\Lambda}$ and $\Sigma^0\overline{\Sigma}^0$. More in details the angular distribution of the decay $\psi(2S) \to \Sigma^0\overline{\Sigma}^0$ exhibits an opposite trend with respect to that of the other three channels: $J/\psi \to \Lambda\overline{\Lambda}$, $J/\psi \to \Sigma^0\overline{\Sigma}^0$ and $\psi(2S) \to \Lambda\overline{\Lambda}$. We define a model to explain the origin of this phenomenon.Comment: 6 pages, 7 figures, to be published in Chinese Physics

On relativization of the Sommerfeld-Gamow-Sakharov factor

The Sommerfeld-Gamow-Sakharov factor is considered for the general case of arbitrary masses and energies. It is shown that the scalar triangular one-loop diagram gives the Coulomb singularity in radiative corrections at the threshold. The singular part of the correction is factorized at the complete Born cross section regardless of its partial wave decomposition. Different approaches to generalize the factor are discussed.Comment: 9 pages, 4 figures; references and discussion are extende

No Sommerfeld resummation factor in e+e- -> ppbar ?

The Sommerfeld rescattering formula is compared to the e+e- -> ppbar BaBar data at threshold and above. While there is the expected Coulomb enhancement at threshold, two unexpected outcomes have been found: |G^p (4M_p^2)|= 1, like for a pointlike fermion, and moreover data show that the resummation factor in the Sommerfeld formula is not needed. Other e+e- -> baryon-antibaryon cross sections show a similar behavior near threshold.Comment: 9 pages, 6 figure

Test beam results with prototypes for the new Cylindrical GEM Inner Tracker of the BESIII experiment

A cylindrical GEM tracker is under construction in order to replace and improve the inner tracking system of the BESIII experiment. Tests with planar chamber prototypes were carried out on the H4 beam line of SPS (CERN) with muons of 150 GeV/c momentum, to evaluate the efficiency and resolution under different working conditions. The obtained efficiency was in the 96–98% range. Two complementary algorithms for the position determination were developed: the charge centroid and the μ-TPC methods. With the former, resolutions < 100 μm and < 200 μm were achieved without and with magnetic field, respectively. The μTPC improved these results. By the end of 2016, the first cylindrical prototype was tested on the same beam line. It showed optimal stability under different settings. The comparison of its performance with respect to the planar chambers is ongoing. Here, the results of the planar prototype tests will be addressed