Υ(nS)\Upsilon(nS) polarizations in pppp collisions at s=\sqrt{s}= 7 and 8 TeV by the LHCb collaboration

A polarization measurement carried out for the $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$ mesons produced in pp collisions at $\sqrt{s}=$ 7 and 8 TeV is presented. Data samples used for the polarization measurement were collected by the LHCb experiment during the 2011 and 2012 data taking runs with integrated luminosities of 1 and 2 fb$^{-1}$, respectively. The measurement has been performed in three polarization frames, using an angular distribution analysis of the $\Upsilon\to\mu^{+}\mu^{-}$ decays in the kinematic region of the $\Upsilon$ transverse momentum $p_{T}^{\Upsilon}<30$ GeV/c and rapidity $2.2<y^{\Upsilon}<4.5$. No large polarization is observed.Comment: Proceedings of XVII International Workshop on High Energy Spin Physics (DSPIN-17), Dubna, Russia, September 11 - 15, 2017; All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-028.htm

The Schlesinger system and isomonodromic deformations of bundles with connections on Riemann surfaces

We introduce a way of presentation of pairs $(E,\nabla)$, where $E$ is a bundle on a Riemann surface and $\nabla$ is a logarithmic connection in $E$, which is based on a presentation of the surface as a factor of the exterior of the unit disc. In this presentation we write the local equation of isomonodormic deformation of pairs $(E,\nabla)$. These conditions are written as a modified Schlesinger system on a Riemann sphere (and in the typical case just as an ordinary Schlesinger system) plus some linear system.Comment: 19 pages, final version accepted to publicatio

Kaon experiments at CERN: NA48 and NA62

Searches for violation of lepton flavour universality and lepton number conservation in kaon decays by the NA62 and NA48/2 experiments at CERN, status and future plans of the CERN kaon programme are presented. A precision measurement of the helicity-suppressed ratio $R_K$ of the $K^\pm\to e^\pm\nu$ and $K^\pm\to\mu^\pm\nu$ decay rates has been performed using the full data set collected by the NA62 experiment in 2007--2008. The result is $R_K=(2.488\pm0.010)\times10^{-5}$, in agreement with the Standard Model expectation. An improved upper limit on the rate of the lepton number violating $K^\pm\to\pi^\mp\mu^\pm\mu^\pm$ decay from the NA48/2 experiment (2003--2004 data set) is presented. Finally, the NA62 project aiming at a measurement of the branching ratio of the ultra-rare decay $K^+\to\pi^+\nu\bar\nu$ at 10% precision is discussed.Comment: Talk given at PhiPsi 2011 conference (Novosibirsk, Russia, September 2011). To be published in Nucl.Phys.B Proc.Sup