Selection and study of the Bs0→Ds−π+B_{s}0 \to D_{s}-\pi^{+} decay at LHCb

The decay channel B_s0 -> D_s- pi+ will be used in LHCb to extract the physics parameters Delta M_s and Delta Gamma_s and the wrong tag fraction omega. This flavour specific decay may also serve as a control channel for B_s0 -> D_s+- K+- which is used to extract the CP-violating phases gamma + phi_s. This study of fully Monte Carlo simulated events shows that an annual signal yield of (111.4 +- 0.5)k reconstructed, triggered and selected events can be obtained. The background-to-signal ratio for this channel is expected to be 0.83 +- 0.09 where the dominant source of background is assumed to be bb~. The effective combined tagging efficiency is expected to be (6.10 +-0.19)%. The proper time resolution is also investigated and a value of 41.8 fs is found. This resolution is dominated by the spatial resolution on the B_s-decay vertex. This is still a very good resolution which will allow to resolve the fast B_s0B_s~0 oscillations. The efficiency of selection is analysed as a function of the true proper time before and after trigger. The results show that this efficiency is smaller for low proper times (due to the cuts requiring a displaced secondary vertex) and is also decreasing for large proper time. This effect is found to be enhanced by the Level-0 trigger and even more by the Level-1 trigger. Finally, the sensitivity to Delta M_s is calculated and the analysis shows that this parameter will be measurable (with a statistical significance of at least 5 sigma) up to 46 ps-1

Probability distributions for velocity components along parallel (circles) and perpendicular (squares) directions to the confining rods for IDA configurations.

<p>Solid symbols represent sandwiched spheres. Hollow symbols represent free particles. Lines represent best fit to Gaussian curves.</p

Liberated area due to aggregation of rods for DDA dimers (solid green line), IDA configurations (solid red line), and both mechanisms (solid black line) as a function of time from the start of the experiment.

<p>Dashed lines correspond to a function fitting as described in text.</p

Survival times of an isolated IDA configuration as a function of dimensionless acceleration.

<p>Survival times of an isolated IDA configuration as a function of dimensionless acceleration.</p

Construction and Optical Testing of Inflatable Membrane Mirror Using Structured Light Technique

Construction and characterization of an inflatable mirror prototype made out of flexible polymeric membranes are being presented. Surfaces were curved by imposing a slight excess of air pressure. Lightweighted, lowcost, and commercially available materials were selected in order to produce solar concentration elements at competitive prices. In this sense, large-area, image-forming mirrors with low optical acuity were achieved by concentration purposes. Optical characterization of the mirror’s shape at a given pressure or curvature radius was done by means of a structuredlight technique with a resolution of 0.1 mm finding a conical shape acquired by the inflated mirror as the best approximation. Concentration ratio achieved for a focal length of 5068 mm was of 25.1 suns, making a promising approach for lowering initial investment costs in applications such as hot-water, parabolic dish with Stirling engines, or concentrated photovoltaic electricity generation