Direct search for light gluinos

We present the results for a direct search for light gluinos through the appearance of $\eta\rightarrow 3\pi^{0}$ with high transverse momentum in the vacuum tank of the NA48 experiment at CERN. We find one event within a lifetime range of $10^{-9}-10^{-3}$s and another one between $10^{-10}-10^{-9}$s. Both events are consistent with the expected background from neutrons in the beam, produced by 450 GeV protons impinging on the Be targets, which interact with the residual air in the tank. From these data we give limits on the production of the hypothetical $g\widetilde{g}$ bound state, the $R^0$ hadron, and its $R^0\rightarrow\eta\widetilde{\gamma}$ decay in the $R^0$ mass range between 1 and 5~GeV

New high statistics measurement of Ke4K_{e4} decay form factors and ππ\pi\pi scattering phase shifts

We report results from a new measurement of the $K_{e4}$ decay $K^{\pm} \rightarrow \pi^{+}\pi^{-}e^{\pm}\nu$ by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670000 $K_{e4}$ decays in both charged modes collected in 2003. The form factors of the hadronic current (F, G, H) and $\pi\pi$ phase difference ($\delta=\delta_{s}-\delta_{p}$) have been measured in ten independent bins of the $\pi\pi$ mass spectrum to investigate the variation. A sizeable acceptance at large $\pi\pi$ mass, a low background and a very good resolution contribute to an improved experimental accuracy, a factor two better than in the previous measurement, when extracting the $\pi\pi$ scattering lengths $a^{0}_{0}$ and $a^{2}_{0}$. Under the assumption of isospin symmetry and using numerical solutions of the Roy equations, the following values are obtained in the plane ($a^{0}_{0}, a^{2}_{0}): a^{0}_{0}=0.233 \pm 0.016_{stat} \pm 0.007_{syst}, a^{2}_{0}=-0.0471 \pm 0.011_{stat} \pm 0.004_{syst}$. The presence of potentially large isospin effects is also considered and will allow comparison with precise predictions from Chiral Perturbation Theory

Search for direct CP violating charge asymmetries in K±→π±π+π−K^\pm\to\pi^\pm\pi^+\pi^- and K±→π±π0π0K^\pm\to\pi^\pm\pi^0\pi^0 decays

A measurement of the direct CP violating charge asymmetries of the Dalitz plot linear slopes $A_g=(g^+-g^-)/(g^++g^-)$ in $K^\pm\to\pi^\pm\pi^+\pi^-$ and $K^\pm\to\pi^\pm\pi^0\pi^0$ decays by the NA48/2 experiment at CERN SPS is presented. A new technique of asymmetry measurement involving simultaneous $K^+$ and $K^-$ beams and a large data sample collected allowed a result of an unprecedented precision. The charge asymmetries were measured to be $A^c_g=(-1.5\pm2.2)\times10^{-4}$ with $3.11\times 10^9$ $K^{\pm}\to\pi^\pm\pi^+\pi^-$ decays, and $A^n_g=(1.8\pm1.8)\times10^{-4}$ with $9.13\times 10^7$ $K^{\pm}\to\pi^\pm\pi^0\pi^0$ decays. The precision of the results is limited mainly by the size of the data sample.Comment: 29 pages, 9 figures. An updated version accepted by the EPJ