Wuppertal, Universiẗat, Diss., 1999.

Universiẗat, Diss., 2003--Münster (Westfalen).

Universiẗat, Diss., 1999--Wuppertal.

Decays of neutral D mesons to final states containing K + π's could provide evidence for CP-violation from a source not accounted for in the Standard Model. Due to the interference between Cabibbo-favored and Cabibbo-suppressed transitions, a decay rate asymmetry of D0 → K0S π0 compared to D0 → K0Lπ0 has been predicted to be non-zero. If New Physics interferes in doubly Cabibbo-suppressed D decays, the measurement of this asymmetry would differ from the predicted value and may provide evidence for CP-violation beyond the CKM mechanism. I present an analysis method to measure this branching fraction asymmetry, R(D0) ≡ B(D0→K0S π0)−B(D0→K0L π0)/(B(D0→K0Sπ0)+B(D0→K0Lπ0)), utilizing e+e− → cc events in the Belle dataset. / Doctor of Philosophy / The Universe appears to be made almost entirely of matter rather than antimatter; however, matter and antimatter should have been created in equal amounts in the Big Bang. We do not know exactly why we observe so much more matter as compared to antimatter. The Standard Model (SM) of particle physics accounts for some of the asymmetry through Charge-Parity (CP) symmetry violation, which explains how particles behave differently than their corresponding antiparticles. In the current state of the SM, some CP-violation is allowed in decays via the weak force, but the theory does not account for enough CP violation to explain the amount of matter-antimatter asymmetry observed in the Universe. Decays of a D meson to a kaon (K meson) plus one or more pions (π mesons) via a new mechanism beyond the weak force could provide evidence of a new source of CP-violation. In this analysis, I present a method for analyzing the decays of neutral D mesons to a neutral kaon and a neutral pion in the Belle dataset to test the SM.

Within the PANDA experiment, proton anti-proton collisions will be studied in order to gain knowledge about the strong interaction. One interesting aspect is the production and decay of charmed hadrons. The charm quark is three orders of magnitude heavier than the light up- and down-quarks which constitue the matter we consist of. The detection of charmed particles is a challenge since they are rare and often hidden in a large background. There will be three different targets used at the experiment; the cluster-jet, the untracked pellet and the tracked pellet. All three targets meet the experimental requirements of high luminosity. However they have different properties, concerning the effect on beam quality and the determination of the interaction point. In this thesis, simulations and reconstruction of the charmed D-mesons using the three different targets have been made. The data quality, such as momentum resolution and vertex resolution has been studied, as well as how the different targets effect the reconstruction efficiency of D-meson have been analysed. The results are consistent with the results from a similar study in 2006, but provide additional information since it takes the detector response into account. Furthermore, a new target distribution have been implemented in the software package. This is the first results obtained from a cylindrical target distribution. The results are very important for PANDA since they show the limitations of different target types regarding the possibilities to reduce background. Simulations with the new target distribution have been made for all three targets and the results are presented.

The diffractive open charm production is studied using data from 2006-2007, when the leading proton measurement by H1 Very Forward Proton Spectrometer was provided. The charm production is tagged by the decay products of D∗ meson. The cross section of e+ p → e+ D∗ X p in photoproduction regime defined by the value of virtuality Q2 < 2 GeV is determined and corrected for the detector effects. The diffractive D∗ meson photoproduction cross section is compared with the hadron level MC Rapgap prediction based on diffractive parton distribution functions extracted from inclusive ep DIS measurements. Measurement of leading proton provides a unique opportunity to investigate the response of forward detectors for the diffractive events. Using such events, the performance of the large rapidity gap selection is examined.

No description available.

<p>The PANDA experiment is a part of the future FAIR accelerator facility and will study the strong interaction by detecting the reaction products from antiproton-proton annihilations in a near full solid-angle configuration. One option for the internal proton target in PANDA is frozen micro-spheres of hydrogen, so-called pellets.</p><p>Such a pellet target is interesting because of the unique characteristics it offers; the high target thickness, the small interaction volume, the minimal gas load on the vacuum system, and the possibility of tracking individual pellets. Nevertheless, it is possible to allocate the bulky equipment needed to produce the pellets at a few meters away from the beam. This way particle detectors can be located close and almost fully around the interaction point.</p><p>This thesis is devoted to the optimization of a pellet target. To perform measurements, a Pellet-Test Station was built at The Svedberg Laboratory, Uppsala. For the first time, experimental results show the pellet distribution in space and time, and in addition, the vacuum along the pellet pipes. Furthermore, dedicated measurements carried out at CELSIUS/WASA demonstrate the existence of pellet heating as a result of beam-target interactions.</p><p>In performing calculations, the potential problems with pellet heating at PANDA are outlined. Moreover, to look at the consequences for the desired physics, a reaction involving short-lived D-mesons has been used to show the advantages of pellets compared to a more spacious target.</p><p>In conclusion, these studies lead to a deeper understanding of the pellet properties, which makes it possible to suggest future improvements, such as cooling with no vibrations.</p>

The PANDA experiment is a part of the future FAIR accelerator facility and will study the strong interaction by detecting the reaction products from antiproton-proton annihilations in a near full solid-angle configuration. One option for the internal proton target in PANDA is frozen micro-spheres of hydrogen, so-called pellets. Such a pellet target is interesting because of the unique characteristics it offers; the high target thickness, the small interaction volume, the minimal gas load on the vacuum system, and the possibility of tracking individual pellets. Nevertheless, it is possible to allocate the bulky equipment needed to produce the pellets at a few meters away from the beam. This way particle detectors can be located close and almost fully around the interaction point. This thesis is devoted to the optimization of a pellet target. To perform measurements, a Pellet-Test Station was built at The Svedberg Laboratory, Uppsala. For the first time, experimental results show the pellet distribution in space and time, and in addition, the vacuum along the pellet pipes. Furthermore, dedicated measurements carried out at CELSIUS/WASA demonstrate the existence of pellet heating as a result of beam-target interactions. In performing calculations, the potential problems with pellet heating at PANDA are outlined. Moreover, to look at the consequences for the desired physics, a reaction involving short-lived D-mesons has been used to show the advantages of pellets compared to a more spacious target. In conclusion, these studies lead to a deeper understanding of the pellet properties, which makes it possible to suggest future improvements, such as cooling with no vibrations.

Developments in high-performance computing instruments and advancements in the numerical algorithms combined with lattice gauge theory make it possible to simulate Quantum Chromodynamics (QCD), the theory of strongly-interacting quarks and gluons, numerically at nearly physical light-quark masses. In this work we present our results for the $D^*Dpi$ coupling constant as simulated on $32^3 imes 64$, unquenched $2+1$-flavor lattices. We estimate the coupling at the chiral limit as $g_{D^*Dpi} = 16.23 pm 1.71$, which is in good agreement with its experimental value $g^{(exp)}_{D^*Dpi} = 17.9pm0.3pm1.9$ as obtained by CLEO II Collaboration.