19 research outputs found
Some remarks on PM2.5
Since 1970, the General Physics Department of «UniversitĂ degli Studi di Torino» has carried out a project research, on inorganic solid particulate matter. The special issue of Annals of Geophysics, published for Professor Giorgio FioccoÂs 70th birthday, gives us the possibility to make some important remarks on this topic, focusing on PM2.5. This has been possible using all the old and new experimental data of the measures made by the authors of this paper since 1970
Observation of X(3872) production in pp collisions at âs=7TeV
Using 34.7 pbâ1 of data collected with the LHCb
detector, the inclusive production of the X(3872) meson in
pp collisions at âs = 7 TeV is observed for the first time.
Candidates are selected in the X(3872)âJ/ÏÏ+Ïâ decay
mode, and used to measure Ï(ppâX(3872)+anything)B(X(3872)âJ/ÏÏ+Ïâ) = 5.4 ±1.3 (stat)±0.8 (syst) nb, where Ï(pp âX(3872) + anything) is the inclusive production cross section of X(3872) mesons with rapidity in the range 2.5â4.5 and transverse momentum in the range 5â20 GeV/c. In addition the masses of both the X(3872) and Ï(2S) mesons, reconstructed in the J/ÏÏ+Ïâ final state, are measured to be mX(3872) = 3871.95± 0.48 (stat)±0.12 (syst) MeV/c2 and
mÏ(2S) = 3686.12±0.06 (stat) ±0.10 (syst) MeV/c2
Observation of and search for decays
The first observation of the decay is reported
using proton-proton collision data corresponding to an integrated luminosity of
recorded by the LHCb experiment at centre-of-mass energies
of 7 and 8 TeV. The resonance is produced in the decay . The product of branching fractions normalised to that for
the intermediate state, , is measured to be
\begin{align*} {\cal R}_{\eta_{c}(2S)}\equiv\frac{{\mathcal B}(B^{+} \to
\eta_{c}(2S) K^{+}) \times {\mathcal B}(\eta_{c}(2S) \to p \bar p)}{{\mathcal
B}(B^{+} \to J/\psi K^{+}) \times {\mathcal B}(J/\psi\to p \bar p)} =~& (1.58
\pm 0.33 \pm 0.09)\times 10^{-2}, \end{align*} where the first uncertainty is
statistical and the second systematic. No signals for the decays and
are seen, and the 95\% confidence level upper limits on their relative
branching ratios are % found to be and
. In addition, the mass differences between the
and the states, between the and the
states, and the natural width of the are measured as
\begin{align*} M_{J/\psi} - M_{\eta_{c}(1S)} =~& 110.2 \pm 0.5 \pm 0.9 \rm \,
MeV, M_{\psi(2S)} -M_{\eta_{c}(2S)} =~ & 52.5 \pm 1.7 \pm 0.6 \rm \, MeV,
\Gamma_{\eta_{c}(1S)} =~& 34.0 \pm 1.9 \pm 1.3 \rm \, MeV. \end{align*}Comment: 16 pages, 2 figures All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-016.htm