3,148 research outputs found
Exotic Hadrons with Hidden Charm and Strangeness
We investigate on exotic tetraquark hadrons of the kind [cs][cbar sbar] by
computing their spectrum and decay modes within a constituent
diquark-antidiquark model. We also compare these predictions with the present
experimental knowledge.Comment: 6 pages, 2 figures, minor changes made, references adde
Charmed Baryonium
We re-analyze the published data on the Y(4630) --> Lambda_c Lambdabar_c and
the Y(4660) --> psi(2S) pi pi with a consistent Ansatz and we find that the two
observations are likely to be due to the same state Y_B with M_{Y_B} = 4660.7
+- 8.7 MeV and Gamma_{Y_B} = 61 +- 23 MeV. Under this hypothesis and
reanalizing also the e+e- --> J/psi pi pi gamma_ISR spectrum we extract B(Y_B
--> Lambda_c Lambdabar_c) / B(Y_B --> psi(2S) pi pi) = 25 +- 7, B(Y_B --> J/psi
pi pi) / B(Y_B --> psi(2S) pi pi) J/psi pi pi)
/ B(Y(4350) --> psi(2S) pi pi) psi(2S)
sigma) / B (Y_B --> psi(2S) f_0)=2.0 +- 0.3. These conclusions strongly support
the hypothesis of Y_B being the first observation of a charmed baryonium
constituted by four quarks. From the analysis of the mass spectrum and the
decay properties we show that Y(4350) and Y_B are respectively consistent with
the ground state and first radial excitation of the L=1 state.Comment: Corrected phase space normalization in the fit
SuperB physics opportunities
The SuperB project in Tor Vergata (Italy) aims at investigating flavor physics with a data sample two orders of magnitude larger than the B-Factories that have operated for more than a decade. In the era of LHC this represents
a unique opportunity to perform complementary indirect searches for new physics effects. In addition its design characteristics make it a flavor factory with an even
broader physics reach. This paper summarizes the host of physics opportunities that will be opened by this experiment and the project status
On the Spin of the X(3872)
Whether the much studied X(3872) is an axial or tensor resonance makes an
important difference to its interpretation. A recent paper by the BaBar
collaboration raised the viable hypothesis that it might be a 2-+ state based
on the 3 pions spectrum in the X -> J/psi omega decays. Furthermore, the Belle
collaboration published the 2 pions invariant mass and spin-sensitive angular
distributions in X -> J/psi rho decays. Starting from a general parametrization
of the decay amplitudes for the axial and tensor quantum numbers of the X, we
re-analyze the whole set of available data. The level of agreement of the two
spin hypotheses with data is interpreted with a rigorous statistical approach
based on Monte Carlo simulations in order to be able to combine all the
distributions regardless of their different levels of sensitivity to the spin
of the X. Our analysis returns a probability of 5.5% and 0.1% for the agreement
with data of the 1++ and 2-+ hypotheses, respectively, once we combine the
whole information (angular and mass distributions) from both channels. On the
other hand, the separate analysis of J/psi rho (angular and mass distributions)
and J/psi omega (mass distribution) indicates that the 2-+ assignment is
excluded at the 99.9% C.L. by the former case, while the latter excludes at the
same level the 1++ hypothesis. There are therefore indications that the two
decay modes behave in a different way.Comment: 12 pages, 9 figures, 2 tables. Added angular distributions, which
lead to different conclusion
Higher Tetraquark Particles
There are strong arguments favoring a four-quark interpretation of sub-GeV
light scalar mesons and the diquark-antidiquark body-plan of the tetraquark
seems to provide the most convincing picture. The building diquarks of these
particles are assumed to be spin zero objects. In this paper we explore the
possibility that radially excited aggregations of spin zero or spin one
diquarks might exist and discuss the possibility of the Y(2175) state observed
by BaBar and confirmed by BES being one such state.Comment: 8 pages, 4 figure
Silicon Photo-Multiplier radiation hardness tests with a beam controlled neutron source
We report radiation hardness tests performed at the Frascati Neutron
Generator on silicon Photo-Multipliers, semiconductor photon detectors built
from a square matrix of avalanche photo-diodes on a silicon substrate. Several
samples from different manufacturers have been irradiated integrating up to
7x10^10 1-MeV-equivalent neutrons per cm^2. Detector performances have been
recorded during the neutron irradiation and a gradual deterioration of their
properties was found to happen already after an integrated fluence of the order
of 10^8 1-MeV-equivalent neutrons per cm^2.Comment: 7 pages, 6 figures, Submitted to Nucl. Inst. Meth.
Search for Neutron Flux Generation in a Plasma Discharge Electrolytic Cell
Following some recent unexpected hints of neutron production in setups like
high-voltage atmospheric discharges and plasma discharges in electrolytic
cells, we present a measurement of the neutron flux in a configuration similar
to the latter. We use two different types of neutron detectors,
poly-allyl-diglicol-carbonate (PADC, aka CR-39) tracers and Indium disks. At
95% C.L. we provide an upper limit of 1.5 neutrons cm^-2 s^-1 for the thermal
neutron flux at ~5 cm from the center of the cell. Allowing for a higher energy
neutron component the largest allowed flux is 64 neutrons cm^-2 s^-1. This
upper limit is two orders of magnitude smaller than what previously claimed in
an electrolytic cell plasma discharge experiment. Furthermore the behavior of
the CR-39 is discussed to point our possible sources of spurious signals.Comment: 4 pages, 3 figure
- …