Angular and Current-Target Correlations in Deep Inelastic Scattering at HERA

Correlations between charged particles in deep inelastic ep scattering have been studied in the Breit frame with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb-1. Short-range correlations are analysed in terms of the angular separation between current-region particles within a cone centred around the virtual photon axis. Long-range correlations between the current and target regions have also been measured. The data support predictions for the scaling behaviour of the angular correlations at high Q2 and for anti-correlations between the current and target regions over a large range in Q2 and in the Bjorken scaling variable x. Analytic QCD calculations and Monte Carlo models correctly describe the trends of the data at high Q2, but show quantitative discrepancies. The data show differences between the correlations in deep inelastic scattering and e+e- annihilation.Comment: 26 pages including 10 figures (submitted to Eur. J. Phys. C

Plastisol Foaming Process. Decomposition of the Foaming Agent, Polymer Behavior in the Corresponding Temperature Range and Resulting Foam Properties

The decomposition of azodicarbonamide, used as foaming agent in PVC - plasticizer (1/1) plastisols was studied by DSC. Nineteen different plasticizers, all belonging to the ester family, two being polymeric (polyadipates), were compared. The temperature of maximum decomposition rate (in anisothermal regime at 5 K min-1 scanning rate), ranges between 434 and 452 K. The heat of decomposition ranges between 8.7 and 12.5 J g -1. Some trends of variation of these parameters appear significant and are discussed in terms of solvent (matrix) and viscosity effects on the decomposition reactions. The shear modulus at 1 Hz frequency was determined at the temperature of maximum rate of foaming agent decomposition, and differs significantly from a sample to another. The foam density was determined at ambient temperature and the volume fraction of bubbles was used as criterion to judge the efficiency of the foaming process. The results reveal the existence of an optimal shear modulus of the order of 2 kPa that corresponds roughly to plasticizer molar masses of the order of 450 ± 50 g mol-1. Heavier plasticizers, especially polymeric ones are too difficult to deform. Lighter plasticizers such as diethyl phthalate (DEP) deform too easily and presumably facilitate bubble collapse

Angular and Current-target Correlations in Deep Inelastic Scattering at HERA

Correlations between charged particles in deep inelastic e+ p scattering have been studied in the Breit frame with the ZEUS detector at HERA using an integrated luminosity of 6.4pb-1. Short-range correlations are analysed in terms of the angular separation between current-region particles within a cone centred around the virtual photon axis. Long-range correlations between the current and target regions have also been measured. The data support predictions for the scaling behaviour of the angular correlations at high Q2 and for anti-correlations between the current and target regions over a large range in Q2 and in the Bjorken scaling variable x. Analytic QCD calculations and Monte Carlo models correctly describe the trends of the data at high Q2, but show quantitative discrepancies. The data show differences between the correlations in deep inelastic scattering and e+e- annihilation

Mean-field transport theory for the two-flavour NJL model

By making decomposition of the Wigner function simultaneously in both the spinor and the isospin spaces we derive a set of kinetic equations for the quark distribution functions and the spin densities. A detailed analysis of the consequences imposed by the chiral invariance on the form of the transport equations is presented.Comment: Revtex, 25 pages, no figure

1ST DETERMINATION OF CP VIOLATION PARAMETERS FROM K(0)-(K)BAR-0 DECAY ASYMMETRY

{We report the first determination of CP violation parameters from particle-antiparticle asymmetry in the decay of neutral kaons into two charged pions. Observation of such an asymmetry is direct proof of CP violation. A fit to the asymmetry enabled a determination of the parameter-eta+- to be made, yielding the result \textbackslash{}eta+-\textbackslash{} = {[}2.32 +/- 0.14 (stat. ) +/- 0.03 (syst.)] X 10(-3) and phi+- = 42.3-degrees +/- 4.4-degrees (stat.) +/- 0.4-degrees (syst. ), with an additional uncertainty of +/-1.0-degrees due to the error on the present published value of DELTA-m, the K(L)0-K(S)0 mass difference. The magnitudes of both statistical and systematic errors will be significantly reduced in the future.

Observation of the CP-conserving K-S->pi(+)pi(-)pi(0) decay amplitude

The interference between CP-conserving K-S and K-L –> pi(+)pi(-)pi(0) decay amplitudes was observed by studying the decay rate asymmetries between initial K-0 and (K) over bar(0) separately for the phase space regions E(CM)(pi(+)) > E(CM)(pi(-)) and E(CM)(pi(+)) < E(CM)(pi(-)) For the parameter lambda we found Re(lambda) = 0.036 +/- 0.010(stat.)(-0.003)(+0.002)(syst.) and Im(lambda) consistent with zero, leading to a branching ratio B = [4.1(-1.9)(+2.5)(stat.)(-0.6)(+0.5)(syst.)] x 10(-7) for the CP-conserving K-S –> pi(+)pi(-)pi(0) decay

MEASUREMENT OF THE K-L-K-S MASS DIFFERENCE USING SEMILEPTONIC DECAYS OF TAGGED NEUTRAL KAONS

We present a new measurement of the K-L-K-S mass difference (Delta m) using semileptonic decays of neutral kaons. The measurement yields Delta m = (0.5274 +/- 0.0029(stat.) +/- 0.0005(syst.)) x 10(10)(h) over bar/s

PROSPECTS FOR B-PHYSICS IN THE NEXT DECADE

In these lectures I review what has been learned from studies of b-quark decays, including semileptonic decays (Vub and Vcb), B o −B o mixing and rare B decays. Then a discussion on CP violation follows, which leads to a summary of plans for future experiments and what is expected to be learned from them