Prompt K_short production in pp collisions at sqrt(s)=0.9 TeV

The production of K_short mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements of the beam currents, sizes and positions, and is found to be 6.8 +/- 1.0 microbarn^-1. The differential prompt K_short production cross-section is measured as a function of the K_short transverse momentum and rapidity in the region 0 < pT < 1.6 GeV/c and 2.5 < y < 4.0. The data are found to be in reasonable agreement with previous measurements and generator expectations.Comment: 6+18 pages, 6 figures, updated author lis

Measurement of sigma (pp -> bbX) at √s=7 TeV in the forward region

Decays of b hadrons into final states containing a D-0 meson and a muon are used to measure the bb; production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < eta < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or b-flavoured hadrons is (75.3 +/- 5.4 +/- 13.0) mu b

Hydrostatic pressure and electric field effects on the normalized binding energy in asymmetrical quantum wells

We have investigated the simultaneous effects of the hydrostatic pressure and electric field on the ground subband level and on normalized binding energy of an on-center donor in asymmetrical GaAs/AlGaAs quantum wells within the effective-mass approximation and a variational approach. We found that the well size at which the impurity energy changes from positive to negative value (turning point) strongly depends on the asymmetry and hydrostatic pressure. As a key result, we suggest that the study of the normalized binding energy for various values of the electric field in direct and inverse polarization regimes can be used to feel the quantum well asymmetry and to unambiguously find out the effective pressure acting on a given heterostructure