3,458 research outputs found
Unexpected features of e+e-->ppbar and e+e-->lambda-lambdabar cross sections near threshold
Unexpected features of the BaBar data on e+e- in baryon-antibaryon cross
sections are discussed. These data have been collected, with unprecedented
accuracy, by means of the initial state radiation technique, which is
particularly suitable in giving good acceptance and energy resolution at
threshold. A striking feature observed in the BaBar data is the non-vanishing
cross section at threshold for all these processes. This is the expectation due
to the Coulomb enhancement factor acting on a charged fermion pair. In the case
of e+e- in proton-antiproton it is found that Coulomb final state interactions
largely dominate the cross section and the form factor is |G^p(4M^2_p)|~1,
which could be a general feature for baryons. In the case of neutral baryons an
interpretation of the non-vanishing cross section at threshold is suggested,
based on quark electromagnetic interaction and taking into account the
asymmetry between attractive and repulsive Coulomb factors. Besides strange
baryon cross sections are compared to U-spin invariance predictions.Comment: 12 pages, 11 figure
Hunting for asymptotia at LHC
We discuss whether the behaviour of some hadronic quantities, such as the
total cross-section, the ratio of the elastic to the total cross-section, are
presently exhibiting the asymptotic behaviour expected at very large energies.
We find phenomenological evidence that at LHC7 there is still space for further
evolution.Comment: 5 pages, 2 figures, talk given by G. Pancheri at International
Workshop on Diffraction in High-Energy Physics, DIFFRACTION 2012, Puerto del
Carmen, Canary Islands, Spain. To appear in AIP Conf. Pro
Comments on ISR method in modern experiment and influence of final state radiation
We study the effect of final state radiation in the process , in the kinematical conditions of BaBar and BESIII experiment. We show
that this effect could be large, in particular in the low region ( is
the photon energy fraction) and should be taken into account.Comment: 8 pages, 5 figure
A description of the ratio between electric and magnetic proton form factors by using space-like, time-like data and dispersion relations
We use the available information on the ratio between the electric and
magnetic proton form factors coming from recently published space-like data and
from the few available time-like data. We apply a dispersive procedure on these
data to evaluate the behaviour of this ratio, as a complex function, for all
values of q^2.Comment: 12 pages, 7 Encapsulated Postscript figures, uses epsfig, rotating,
exscale, amsmath, cite, latexsym, graphics, color packages, added reference
A Cylindrical GEM Inner Tracker for the BESIII experiment at IHEP
The Beijing Electron Spectrometer III (BESIII) is a multipurpose detector
that collects data provided by the collision in the Beijing Electron Positron
Collider II (BEPCII), hosted at the Institute of High Energy Physics of
Beijing. Since the beginning of its operation, BESIII has collected the world
largest sample of J/{\psi} and {\psi}(2s). Due to the increase of the
luminosity up to its nominal value of 10^33 cm-2 s-1 and aging effect, the MDC
decreases its efficiency in the first layers up to 35% with respect to the
value in 2014. Since BESIII has to take data up to 2022 with the chance to
continue up to 2027, the Italian collaboration proposed to replace the inner
part of the MDC with three independent layers of Cylindrical triple-GEM (CGEM).
The CGEM-IT project will deploy several new features and innovation with
respect the other current GEM based detector: the {\mu}TPC and analog readout,
with time and charge measurements will allow to reach the 130 {\mu}m spatial
resolution in 1 T magnetic field requested by the BESIII collaboration. In this
proceeding, an update of the status of the project will be presented, with a
particular focus on the results with planar and cylindrical prototypes with
test beams data. These results are beyond the state of the art for GEM
technology in magnetic field
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