Recent CP violation and |Vus_{us}| measurements from the NA48 experiment

Results from recent analyses of the NA48 experiment at CERN are compared with other experiments and confronted with theoretical predictions to provide constraints on the CKM matrix and on CP Violation. The observable eta+- is related to the parameters of indirect and direct CPV (eta+- = epsilon + epsilon'). |eta+-| has been determined by measuring the ratio of decay rates: Gamma(K_L to pi+pi-)/Gamma(K_L to pi e nu), using an NA48 run with a dedicated pure high-intensity K_L beam. The main objective of NA48/2 has been to search for direct CP violation by high precision measurement of the asymmetry A_g = (g+ - g-)/(g+ + g-) of the linear slope parameter g in the Dalitz plot of K+- to 3pi decays. The final results from all data samples are summarised and discussed. The decay rates R(Ke3/K2pi), R(Kmu3/K2pi) and R(Kmu3/Ke3) have been measured with charged K decays from special data samples with a low bias trigger in the NA48/2 experiment. Using the latest PDG average for the (K+- to pi+- pi0) normalisation channel, the Ke3 and Kmu3 branching fractions are then used as input to deduce the CKM matrix element Vus

QCD Tests with Kaon Decays

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Kaon Physics at CERN: recent results from the NA48/2 experiment

Semileptonic kaon decays offer the most precise determination of the CKM matrix element |Vus|. The experimental precision is however limited by the knowledge of the form factors of these decays. The NA48/2 experiment presents high precision preliminary measurements of the form factors of the semileptonic decays of charged kaons (K±→ π0l±ν), based on 4.3 million Ke3 and 2.5 million Kμ3 decays, both with negligible background. At the same time a large sample of more than a million charged kaon decays to Ke4 final state (for both charged, K± → π+π−e±ν , and neutral, K± → π0π0e±ν , mode) has been collected, allowing a detailed study of ππ scattering and hadronic form factors. Here we present a much improved determination of the Branching Fraction for both charged and neutral modes and Form Factor for the charged mode

Experimental Study of Crystal Channelling at CERN-SPS for Beam-Halo Cleaning

An efficient and robust collimation system is mandatory for any superconducting hadron collider, in particular for the LHC, which will store a beam of unprecedented high intensity and energy. The usage of highly efficient and short primary bent-crystal collimators might be a possibility for reaching nominal and ultimate LHC intensity. Over the last years, groups in Italy (Ferrara) and Russia (St. Petersburg) have developed crystal production methods, that considerably improve the crystal quality. These developments led, in turn, to a surprising increase in the channeling efficiency and to the recent observation of the âﾜvolume reflectionâ mechanism. The aim of the proposed experiment is the setup of a beam test facility, directing primary protons from the SPS onto a bent silicon crystal, and the quantitative study of single-pass efficiency for all involved processes. Final goal will be the extrapolation of important information on the feasibility of a crystal collimator for halo cleaning in the LHC. The experiment will be performed in the H8 beamline at the CERN SPS where a beam with very small divergence can be provided thus representing a unique facility for tests and characterization of crystals to be used for particle channeling studies

Microsatellites and SNPs linkage analysis in a Sardinian genetic isolate confirms several essential hypertension loci previously identified in different populations

Background. A multiplicity of study designs such as gene candidate analysis, genome wide search (GWS) and, recently, whole genome association studies have been employed for the identification of the genetic components of essential hypertension (EH). Several genome-wide linkage studies of EH and blood pressure-related phenotypes demonstrate that there is no single locus with a major effect while several genomic regions likely to contain EH-susceptibility loci were validated by multiple studies. Methods. We carried out the clinical assessment of the entire adult population in a Sardinian village (Talana) and we analyzed 16 selected families with 62 hypertensive subjects out of 267 individuals. We carried out a double GWS using a set of 902 uniformly spaced microsatellites and a high-density SNPs map on the same group of families. Results. Three loci were identified by both microsatellites and SNP scans and the obtained linkage results showed a remarkable degree of similarity. These loci were identified on chromosome 2q24, 11q23.1–25 and 13q14.11–21.33. Further support to these findings is their broad description present in literature associated to EH or related phenotypes. Bioinformatic investigation of these loci shows several potential EH candidate genes, several of whom already associated to blood pressure regulation pathways. Conclusion. Our search for major susceptibility EH genetic factors evidences that EH in the genetic isolate of Talana is due to the contribution of several genes contained in loci identified and replicated by earlier findings in different human populations

Strong suppression of nuclear-charge changing interactions for 18 TeV/ c In ions channeled through a bent Si crystal

Abstract We present experimental results giving evidence for the strong reduction—a factor of more than 20—of nuclear-charge changing interactions for 18 TeV In 49+ ions channeled through a silicon crystal bent to 7.5, 11.9 and 19.8 mrad. A very small fraction of the deflected ions suffer electromagnetic or nuclear interactions leading to proton loss while traversing the 60 mm long crystal, even though its thickness corresponds to about 0.13 nuclear interaction lengths for an amorphous material. By considering the deflected ions only, we show experimentally that the nuclear-charge pickup reaction believed to be induced by virtual photons is a short-range phenomenon

GENERATION AND DETECTION OF THE POLARIZATION OF MULTI-GEV PHOTONS BY USE OF TWO DIAMOND CRYSTALS

Abstract Presented are experimental results for the difference in pair production probability (the asymmetry) for 5–150 GeV photons polarized parallel and perpendicular to a (110) plane in a 1.5 mm thick diamond 〈100〉 crystal. The photons are produced by interaction of 150 GeV electrons with an aligned diamond 〈100〉 crystal of 0.5 mm thickness. A significant asymmetry is found over the whole energy range, which corresponds to a high degree of linear polarization of the photons as well as a difference in the refractive index. This proof-of-principle result gives the possibility of producing high energy photons with circular polarization by use of a crystal. This might open for several opportunities in high energy physics like for instance the investigation of the contribution of the gluons to the spin of the nucleon

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum