Evidence of a geomagnetic effect on extensive air showers detected with the ARGO-YBJ experiment

The geomagnetic field causes not only the east-west effect on primary cosmic rays but also affects the trajectories of the secondary charged particles in the shower, causing their lateral distribution to be stretched. Thus, both the density of the secondaries near the shower axis and the trigger efficiency of detector arrays decrease. The effect depends on the direction of the showers, thus, introducing a modulation in the measured azimuthal distribution. The azimuthal distribution of the events collected by the ARGO-YBJ detector is deeply investigated for different zenith angles in light of this effect

{Measurement of charm production at central rapidity in proton-proton collisions at s=2.76\sqrt{s}=2.76 TeV}

he pt-differential inclusive production cross sections of the prompt charmed mesons D0, D+, and D∗+ in the rapidity range |y| < 0.5 were measured in proton-proton collisions at √s = 7 TeV at the LHC using the ALICE detector. Reconstructing the decays D0 → K−π+, D+ → K−π+π+, D∗+ → D0π+, and their charge conjugates, about 8,400 D0, 2,900 D+, and 2,600 D∗+ mesons with 1 < pt < 24 GeV/c were counted, after selection cuts, in a data sample of 3.14×108 events collected with a minimum-bias trigger (integrated luminosity Lint = 5 nb−1). The results are described within uncertainties by predictions based on perturbative QCD