The Vertex detector of the LHCb Experiment: The VeLo

The LHCb experiment is the dedicated b physics experiment of the LHC that will study CP violation and rare b decays. Its vertex detector called VeLo (Vertex Locator) has been designed to achieve an impact parameter resolution of 14μm + 35μm/pT and a propertime resolution of 40fs−1. The main components of the detector and module are introduced focusing on the radiation hard front end Beetle chip, the radiation tolerant silicon sensors and the readout system of the detector. In preliminary testbeam results a resolution of 8μm and 4μm for tracks of angle 0.16rad has been measured. Construction, assembly and commissioning are currently on going. The latest commissioning showing the successful performance of the VeLo alignment algorithm

Unravelling the Structure of Magnus' Pink Salt

A combination of multinuclear ultra-wideline solid-state NMR, powder X-ray diffraction (pXRD), X-ray absorption fine structure experiments, and first principles calculations of platinum magnetic shielding tensors has been employed to reveal the previously unknown crystal structure of Magnus’ pink salt (MPS), [Pt(NH3)4][PtCl4], study the isomeric Magnus’ green salt (MGS), [Pt(NH3)4][PtCl4], and examine their synthetic precursors K2PtCl4 and Pt(NH3)4Cl2·H2O. A simple synthesis of MPS is detailed which produces relatively pure product in good yield. Broad 195Pt, 14N, and 35Cl SSNMR powder patterns have been acquired using the WURST-CPMG and BRAIN-CP/WURST-CPMG pulse sequences. Experimentally measured and theoretically calculated platinum magnetic shielding tensors are shown to be very sensitive to the types and arrangements of coordinating ligands as well as intermolecular Pt–Pt metallophilic interactions. High-resolution 195Pt NMR spectra of select regions of the broad 195Pt powder patterns, in conjunction with an array of 14N and 35Cl spectra, reveal clear structural differences between all compounds. Rietveld refinements of synchrotron pXRD patterns, guided by first principles geometry optimization calculations, yield the space group, unit cell parameters, and atomic positions of MPS. The crystal structure has P-1 symmetry and resides in a pseudotetragonal unit cell with a distance of >5.5 Å between Pt sites in the square-planar Pt units. The long Pt–Pt distances and nonparallel orientation of Pt square planes prohibit metallophilic interactions within MPS. The combination of ultra-wideline NMR, pXRD, and computational methods offers much promise for future investigation and characterization of Pt-containing systems

Momentum asymmetries as CP violating observables

Three body decays can exhibit CP violation that arises from interfering diagrams with different orderings of the final state particles. We construct several momentum asymmetry observables that are accessible in a hadron collider environment where some of the final state particles are not reconstructed and not all the kinematic information can be extracted. We discuss the complications that arise from the different possible production mechanisms of the decaying particle. Examples involving heavy neutralino decays in supersymmetric theories and heavy Majorana neutrino decays in Type-I seesaw models are examined.Comment: 20 pages, 9 figures. Clarifying comments and one reference added, matches published versio

Probing the Top-Higgs Yukawa CP Structure in dileptonic ttˉht \bar t h with M2M_2-Assisted Reconstruction

Constraining the Higgs boson properties is a cornerstone of the LHC program. We study the potential to directly probe the Higgs-top CP-structure via the $t\bar{t}h$ channel at the LHC with the Higgs boson decaying to a bottom pair and top-quarks in the dileptonic mode. We show that a combination of laboratory and $t\bar{t}$ rest frame observables display large CP-sensitivity, exploring the spin correlations in the top decays. To efficiently reconstruct our final state, we present a method based on simple mass minimization and prove its robustness to shower, hadronization and detector effects. In addition, the mass reconstruction works as an extra relevant handle for background suppression. Based on our results, we demonstrate that the Higgs-top CP-phase $(\alpha)$ can be probed up to $\cos\alpha< 0.7$ at the high luminosity LHC.Comment: 25 pages, 11 figures, 3 table

Review of CP Violation Studies with B-Mesons at LHC

The Large Hadron Collider (LHC) proposed at CERN will be the ultimate source of B-mesons. With the large number of B-mesons expected at LHC, a real precision test of CP violation in B-meson decays will become possible. There are already several efforts made to explore this possibility and a summary of those activities is presented.Comment: Standard LaTex, No figure, 10 pages Plenary talk given at 1994 International Workshop on B Physics Physics Beyond the Standard Model at the B Factory Nagoya, October 199