Colombeau generalized functions on manifolds

Eduard NigschZsfassung in dt. SpracheWien, Techn. Univ. u. Univ., Dipl.-Arb., 2006OeBB(VLID)161012

Diffractive Dijet Production with a Leading Proton in ep Collisions at HERA

The cross section of the diffractive process e^+p -> e^+Xp is measured at a centre-of-mass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities Q^2 <2 GeV^2 and in deep-inelastic scattering with 4 GeV^2<Q^2<80 GeV^2. The results are compared to next-to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep-inelastic scattering

Measurement of Jet Production Cross Sections in Deep-inelastic ep Scattering at HERA

A precision measurement of jet cross sections in neutral current deep-inelastic scattering for photon virtualities $5.5<Q^2<80\,{\rm GeV}^2$ and inelasticities $0.2<y<0.6$ is presented, using data taken with the H1 detector at HERA, corresponding to an integrated luminosity of $290\,{\rm pb}^{-1}$. Double-differential inclusive jet, dijet and trijet cross sections are measured simultaneously and are presented as a function of jet transverse momentum observables and as a function of $Q^2$. Jet cross sections normalised to the inclusive neutral current DIS cross section in the respective $Q^2$-interval are also determined. Previous results of inclusive jet cross sections in the range $150<Q^2<15\,000\,{\rm GeV}^2$ are extended to low transverse jet momenta $5<P_{T}^{\rm jet}<7\,{\rm GeV}$. The data are compared to predictions from perturbative QCD in next-to-leading order in the strong coupling, in approximate next-to-next-to-leading order and in full next-to-next-to-leading order. Using also the recently published H1 jet data at high values of $Q^2$, the strong coupling constant $\alpha_s(M_Z)$ is determined in next-to-leading order.A precision measurement of jet cross sections in neutral current deep-inelastic scattering for photon virtualities $5.5<Q^2<80\,{\rm GeV}^2$ and inelasticities $0.2<y<0.6$ is presented, using data taken with the H1 detector at HERA, corresponding to an integrated luminosity of $290\,{\rm pb}^{-1}$. Double-differential inclusive jet, dijet and trijet cross sections are measured simultaneously and are presented as a function of jet transverse momentum observables and as a function of $Q^2$. Jet cross sections normalised to the inclusive neutral current DIS cross section in the respective $Q^2$-interval are also determined. Previous results of inclusive jet cross sections in the range $150<Q^2<15\,000\,{\rm GeV}^2$ are extended to low transverse jet momenta $5<P_{T}^{\rm jet}<7\,{\rm GeV}$. The data are compared to predictions from perturbative QCD in next-to-leading order in the strong coupling, in approximate next-to-next-to-leading order and in full next-to-next-to-leading order. Using also the recently published H1 jet data at high values of $Q^2$, the strong coupling constant $\alpha_s(M_Z)$ is determined in next-to-leading order.A precision measurement of jet cross sections in neutral current deep-inelastic scattering for photon virtualities $5.5<Q^2 <80\,\mathrm {GeV}^2$ and inelasticities $0.2<y<0.6$ is presented, using data taken with the H1 detector at HERA, corresponding to an integrated luminosity of $290\,\mathrm {pb}^{-1}$ . Double-differential inclusive jet, dijet and trijet cross sections are measured simultaneously and are presented as a function of jet transverse momentum observables and as a function of $Q^2$ . Jet cross sections normalised to the inclusive neutral current DIS cross section in the respective $Q^2$ -interval are also determined. Previous results of inclusive jet cross sections in the range $150<Q^2 <15{,}000\,\mathrm {GeV}^2$ are extended to low transverse jet momenta $5<P_\mathrm{T}^\mathrm{jet} <7\,\mathrm {GeV}$ . The data are compared to predictions from perturbative QCD in next-to-leading order in the strong coupling, in approximate next-to-next-to-leading order and in full next-to-next-to-leading order. Using also the recently published H1 jet data at high values of $Q^2$ , the strong coupling constant $\alpha _s(M_Z)$ is determined in next-to-leading order

Exclusive ρ0\rho^0 Meson Photoproduction with a Leading Neutron at HERA

A first measurement is presented of exclusive photoproduction of $\rho^0$ mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years $2006$ and $2007$ at a centre-of-mass energy of $\sqrt{s}=319$ GeV and correspond to an integrated luminosity of $1.16$ pb$^{-1}$. The $\rho^0$ mesons with transverse momenta $p_T0.35$, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality $Q^2 < 2$ GeV$^2$, the total energy of the photon-proton system $20 < W_{\gamma p} < 100$ GeV and the polar angle of the leading neutron $\theta_n < 0.75$ mrad. The cross section of the reaction $\gamma p \to \rho^0 n \pi^+$ is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a $\rho^0$ meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, $\sigma^{\rm el}(\gamma\pi^+ \to \rho^0\pi^+)$, is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction $\gamma p\to\rho^0 n \pi^+$

Measurement of Dijet Production in Diffractive Deep-Inelastic ep Scattering at HERA

A measurement is presented of single- and double-differential dijet cross sections in diffractive deep-inelastic $ep$ scattering at HERA using data collected by the H1 experiment corresponding to an integrated luminosity of 290 pb^{-1}. The investigated phase space is spanned by the photon virtuality in the range of 4<Q^{2}<100 GeV^{2} and by the fractional proton longitudinal momentum loss x_pom<0.03. The resulting cross sections are compared with next-to-leading order QCD predictions based on diffractive parton distribution functions and the value of the strong coupling constant is extracted

Diffractive Dijet Production with a Leading Proton in ep\it ep Collisions at HERA

The cross section of the diffractive process $\it e^{+}p → e^{+}X p$ is measured at a centre-of- mass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton $\it p$ is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities $\it Q^{2} < 2 GeV^{2}$ and in deep-inelastic scattering with $\it 4 GeV^{2} < Q^{2} < 80 GeV^{2}$. The results are compared to next-to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep-inelastic scattering

Exclusive ρ0\rho^{0} Meson Photoproduction with a Leading Neutron at HERA

A first measurement is presented of exclusive photoproduction of $\rho ^{0}$ mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centre-of-mass energy of √s = 319 GeV and correspond to an integrated luminosity of $1.16_{pb}^{−1}$. The $\rho ^{0}$ mesons with transverse momenta $p_{T}$ 0.35, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality $Q^{2}$ < 2 $GeV^{2}$, the total energy of the photon-proton system 20 < $W_{γp}$ < 100 GeV and the polar angle of the leading neutron $θ_{n}$ < 0.75 mrad. The cross section of the reaction $\gamma p → \rho^{0}n\pi^{+}$ is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the pro-ton vertex followed by elastic photoproduction of a $\rho ^{0}$ meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, $\sigma^{el}(\gamma \pi^{+} → \rho^{0}\pi^{+}$), is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction $\gamma p → \rho^{0}n\pi^{+}$

Search for QCD Instanton-Induced Processes at HERA in the High-Q2\it Q^{2} Domain

Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable $x > 10^{-3}$, the inelasticity $0.2< y < 0.7$ and the photon virtuality $150 < Q^2 < 15000$ GeV$^2$. The search is performed using H1 data corresponding to an integrated luminosity of ~$351$ pb$^{-1}$. No evidence for the production of QCD instanton-induced events is observed. Upper limits on the cross section for instanton-induced processes between $1.5$~pb and $6$~pb, at $95\%$~ confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging theory predictions