Measurement of the diffractive structure function in deep inelastic scattering at HERA

This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in $ep$ interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of \xpom, the momentum fraction lost by the proton, of $\beta$, the momentum fraction of the struck quark with respect to \xpom, and of $Q^2$. The \xpom dependence is consistent with the form \xpoma where $a~=~1.30~\pm~0.08~(stat)~^{+~0.08}_{-~0.14}~(sys)$ in all bins of $\beta$ and $Q^2$. In the measured $Q^2$ range, the diffractive structure function approximately scales with $Q^2$ at fixed $\beta$. In an Ingelman-Schlein type model, where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule.Comment: 36 pages, latex, 11 figures appended as uuencoded fil

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

Measurement of Charged and Neutral Current e-p Deep Inelastic Scattering Cross Sections at High Q2

Deep inelastic e-p scattering has been studied in both the charged current (CC) and neutral current (NC) reactions at momentum transfers squared Q(2) above 400 GeV2 using the ZEUS detector at the HERA ep collider. The CC and NC total cross sections, the NC to CC cross section ratio, and the differential cross sections d sigma/dQ(2) are presented. From the Q(2) dependence of the CC cross section, the mass term in the CC propagator is determined to be M(W) = 76 +/- 16 +/- 13 GeV

Ceramic Industry Air Quality. Emissions Into the Atmosphere From Ceramic Tile Processes

The subject of this chapter, air quality associated to the ceramic tile industry, represents a very interesting \u2018real scenario\u2019 in the framework of the whole volume. The reasons can be summarised in this way: (1) the ceramic tile technology includes several significant pollutant emissions into the atmosphere and (2) ceramic industry has generated \u2013 although many years ago and in rather small industrial areas, characterised by large concentrations of factories \u2013 some air quality problems. The Ceramic District of Sassuolo, Italy, can be considered as a significant example of such industrial areas and represents the main reference adopted in this chapter. Another \u2018ceramic district\u2019 is that of Castell\uf3n, Spain, which however is quite different as regards significant factors influencing air quality: factors such as territory, orography, climate, meteorological conditions, urban and industrial settlements and density, road system and traffic, etc. With reference to the Italian ceramic tile industry, this chapter deals with the description and quantification of emissions into the atmosphere from ceramic industries and aims to document the approach adopted, the resources used and the knowledge developed, to drastically reduce the environmental impact of these emissions on air quality. This objective has been successfully achieved, at the point that, in particular, the Italian ceramic tile sector is still working, in the framework of a continuous improvement approach, on its environmental performances, as well as on the exploitation of the results achieved as competitiveness factors