The 2009 Europhysics Conference on High Energy Physics

The SM prediction for the ratio of purely leptonic decay rates of the charged kaon $R_K=\Gamma(K_{e2}/\Gamma(K_{\mu2}))$ has an excellent sub-premille precision. Due to the helicity suppression of the SM contribution, the ratio is sensitive to non-SM effects; in particular, LFV contributions in the MSSM can modify it by a few percent without contradicting any other presently known experimental...

When the mass difference between the lightest slepton, the NLSP, and the lightest neutralino, the LSP, is smaller than the tau mass, the lifetime of the lightest slepton increases in many orders of magnitude with respect to typical lifetimes of other supersymmetric particles. In a general gravity-mediated MSSM, where the LSP is the neutralino, the lifetime of the lightest slepton is...

We present a search for decay of the Y(1S) meson into undetectable final states, using a sample of Y(3S) mesons collected at the PEP-II/BaBar B-factory. We tag the decay of the Y(3S) into the Y(1S) through a pair of charged pions, and measure the rate at which the Y(1S) decays into particles which do not interact with the BaBar detector. Furthermore, we present a search for charged...

We report results of a search for lepton flavor violating $\tau$ decays into $l K_S$ and $l K_S K_S$ using a large data sample accumulated with the Belle detector at the KEKB $e^+ e^-$ collider. The sensitivity to the branching fractions is improved significantly compared to previous experiments.

A search for squarks in R-parity violating supersymmetry is performed using the full ep data sample collected by the H1 detector at HERA at a centre-of-mass energy of 319 GeV. This corresponds to a total integrated luminosity of 440 pb^{-1}. The resonant production of squarks via a Yukawa coupling lambda' is considered, taking into account direct and indirect R-parity violating decay...

We consider scenarios with large flavour violating entries in the squark mass matrices focusing on the mixing between second and third generation squarks. These entries govern both, flavour violating low energy observables on the one hand and squark and gluino decays on the other hand. We first discuss the constraints on the parameter space due to the recent data on $B$ mesons from the...

One or more heavy spin-1 fields may replace the Higgs boson in keeping perturbative unitarity up to a few TeV while at the same time account for the ElectroWeak Precision Tests. We study the Drell-Yan production of heavy vector and axial-vector states of generic Higgsless models at hadron colliders. We analyse in particular the l+l-, WZ, and three SM gauge boson final states. In the l+l- case...

We show how a resonance from the recently proposed Lee-Wick Standard Model could lead to wrong vertex displacements at LHCb. We study which could be the possible 'longest lived' Lee-Wick particle that could be created at LHC, and we study its possible decays and detections. We conclude that there is a region in the parameter space which would give wrong vertex displacements as a unique...

We report on searches for the production of scalar and vector leptoquarks in ppbar collisions at the Tevatron collider. Leptoquarks, which are predicted by several extensions of the Standard Model, are hypothetical particles carrying both lepton and quark flavors. At hadron colliders they can either be pair-produced via the strong interaction or a single leptoquark can be produced in...

A search for physics beyond the Standard Model is performed with high-Q^2 deep inelastic scattering events recorded with the ZEUS and H1 detectors at HERA. Complete data on scattering of polarized electrons and positrons from HERA II running are combined with electron and positron data from HERA I. ZEUS limits are derived on the effective mass scale in eeqq contact interactions, on the...

Searches for excited electrons, excited neutrinos and excited quarks are perfomed using the full $e^{\pm}p$ data sample collected by the H1 experiment at HERA, corresponding to a total luminosity of 475 pb$^{-1}$. The electroweak decays of excited fermions into standard model fernions and $\gamma$, $Z$ or $W$ bosons are considered. No evidence for excited fermion production is found. Mass...