Prof Dr Armin Reichold

Abstract:

We present a measurement of the cross section for production of two or more jets as a function of dijet mass, based on an integrated luminosity of 86 pb^-1 collected with the Collider Detector at Fermilab. Our dijet mass spectrum is described within errors by next-to-leading order QCD predictions using CTEQ4HJ parton distributions, and is in good agreement with a similar measurement from the DØ experiment. ©2000 the American Physical Society.

Abstract:

We present a preliminary study of a new technique for measuring B⁰s mixing and CP violation using the decay B⁰s → J/ψφ, φ K⁺K^-, J/ψ → μ⁺μ^-. This technique utilizes the unequal lifetimes of the B⁰s CP even and odd eigenstates, and an angular variable decomposition of the CP content of the final state. This study is based on CDF Run-I observations and Run-II projections, and predicts that the B⁰s mixing parameter cursive Greek chis can be measured with high accuracy in untagged samples if this approach is adopted. A large CP asymmetry may also be possible to measure. The accuracy of this method is shown to increase for higher values of cursive Greek chis as the lifetime splitting of the CP eigenstates increases. The measurement of cursive Greek chis does not depend on tagging, whereas the observation of a CP-violating asymmetry does.

Abstract:

We present a preliminary study of a new technique for measuring B-s(0) mixing and CP violation using the decay Bs0 --> J/phi phi, phi --> K+K-, J/phi --> mu(+)mu(-). This technique utilizes the unequal lifetimes of the B-s(0) CP even and odd eigenstates, and an angular variable decomposition of the CP content of the final state. This study is based on CDF Run-I observations and Run-II projections, and predicts that the B-s(0) mixing parameter x(s) can be measured with high accuracy in untagged samples if this approach is adopted. A large CP asymmetry may also be possible to measure. The accuracy of this method is shown to increase for higher values of x(s) as the lifetime splitting of the CP eigenstates increases. The measurement of x(s) does nor depend on tagging, whereas the observation of a CP-violating asymmetry does.

Abstract:

Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the standard model. We see no deviations from the expected backgrounds and set upper limits on the production of new processes. We consider in addition the production of light gravitinos and set a limit at 95% F ≥ 217GeV, which excludes gravitino masses smaller than 1.1 × 10−5eV/c2. © 2000 American Physical Society.

Abstract:

We have measured the polarization of J/ψ and ψ(2S) mesons produced in pp collisions at √ = 1.8 TeV using data collected at the Collider Detector at Fermilab during 1992–1995. The polarization of promptly produced J/ψ [ψ(2S)] mesons is isolated from those produced in B-hadron decay and measured over the kinematic range 4 [5.5] < PT < 20 GeV/c and |y| < 0.6. For PT ≾ 12 GeV/c we do not observe significant polarization in the prompt component. © 2000 The American Physical Society.