The 2009 Europhysics Conference on High Energy Physics

Three distribution functions are needed to fully describe the nucleon at leading twist: the unpolarized distribution function q(x), the helicity distribution function $\Delta q(x)$ and the transversity spin distribution function $\Delta_T q(x)$. Transversity and transverse momentum-dependent parton distribution functions (TMDs) are been measured in semi-inclusive deep inelastic scattering...

on behalf of the COMPASS collaboration In addition to constituent qq(bar) pair configurations, four quark states or gluonic excitations like hybrids or glueballs are also expected to contribute to the mesonic spectrum. The most promising way to identify such states allowed by QCD is the search for J^PC quantum number combinations which are forbidden in the constituent quark...

Exclusive production of $\pi^+$ mesons was studied with the HERMES spectrometer at the DESY laboratory by scattering $27.6\,\mathrm{GeV}$ positrons and electrons off a transversely nuclear-polarised hydrogen target. The spin-averaged cross section was measured for values of the virtuality of the exchanged photon $Q^2 > 1\,\mathrm{GeV}^2$ and the invariant mass of the photon-nucleon system...

The physics of strong interactions is undoubtedly one of the most challenging areas of modern science. Quantum Chromo Dynamics (QCD) is reproducing the physics phenomena only at distances much shorter than the size of the nucleon, where perturbation theory can be used yielding results of high precision and predictive power. At larger distance scales, however, perturbative methods...

Assuming a Lagrangian of the strong interaction slightly different from quantum chromodynamics - by replacing the non-Abelian Yang-Mills term by the coupling of two gluons to J(pi)=0+ (the quantum numbers of the vacuum) with subsequent creation of quarks and/or antiquarks - the confinement of quarks is well understood. Further, hadron masses are generated by requiring "massless" quarks, which...

With growing datasets collected by the CDF II experiment, studies of the spectroscopy of mesons containing heavy quarks becomes more exciting. The CDF experiment has good capabilities in both charm and bottom sector. This capability allowed also to contribute to the study of the Zoo of states called X,Y,Z. In this area we present a recent update of the mass measurement of X(3872). The...

Significant progress in description of pi-pi amplitudes has been recently made [1,2]. We present amplitudes fitted both to well known and to newest experimental data. In fits we use additional theoretical constraints from forward dispersion relations, sum rules and from twice and once subtracted dispersion relations. The latter two (so called Roy's and GKPY equations) are derived with...

In the last years a number of exciting discoveries of new hadron states have challenged our description of the hadron spectroscopy. Among the several charmonium states (X(3940), Y(3940), Z(3930)) the most mysterious one is the well established $X(3872)$. It was first discovered by the Belle Collaboration in the $J/\psi \pi \pi$ invariant mass spectrum of the decay $B\rightarrow K^+...

The LHCf detector is ready to take data at the LHC accelerator at CERN. The whole detector has been installed at the beginning of 2008 on both side of LHC collision point 1 (IP1) and the commissioning phase is in a well advanced stage. Thanks to the excellent energy and position resolution of the two sampling calorimeters, LHCf will be able to measure the pion production cross section...