Search for Large Extra Dimensions in Dielectron and Diphoton Production

We report a search for effects of large extra spatial dimensions in pp̅ collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions

Search for Large Extra Dimensions in Dielectron and Diphoton Production

We report a search for effects of large extra spatial dimensions in pp̅ collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions

Heavy Flavours in Collider Experiments

Current issues in the studies of Heavy Flavours in colliders are described with particular emphasis on experiments in which the UK is involved. Results on charm production at HERA are examined and compared to those at the Tevatron. B production rates at the Tevatron as well as the status of B lifetimes and mixing in the LEP collaborations and at the Tevatron are highlighted. The measurement of sin2beta from CDF is described as well as the most recent results on top physics at the Tevatron

Hard single diffractive jet production at D0

Preliminary results from the D{null} experiment on jet production with forward rapidity gaps in {ital p{anti p}} collisions are presented. A class of dijet events with a forward rapidity gap is observed at center-of-mass energies {radical}s = 1800 GeV and 630 GeV. The number of events with rapidity gaps at both center-of-mass energies is significantly greater than the expectation from multiplicity fluctuations and is consistent with a hard single diffractive process. A small class of events with two forward gaps and central dijets is also observed at 1800 GeV. This topology is consistent with hard double pomeron exchange

Jets in deep-inelastic scattering at HERA

Jet cross sections in deep-inelastic scattering over a wide region of phase space have been measured at HERA. These cross section measurements provide a thorough test of the implementation of Quantum Chromodynamics in next-to-leading order (NLO) calculations. They also provide the opportunity to test the consistency of the gluon distribution in the proton as extracted from (mainly) inclusive DIS measurements. Comparison of the cross sections with NLO enables accurate extractions of the strong coupling constant, $\alpha_s$, to be made, several of which are reported here.Comment: Talk presented at "New Trends in HERA Physics", Ringberg Workshop, June 2001. 13pages, 12figure

Search for Violation of CPT and Lorentz Invariance in B s O Meson Oscillations

We present the first search for CPT-violating effects in the mixing of B0s mesons using the full Run II data set with an integrated luminosity of 10.4  fb−1 of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. We measure the CPT-violating asymmetry in the decay B0s→μ±D±s as a function of celestial direction and sidereal phase. We find no evidence for CPT-violating effects and place limits on the direction and magnitude of flavor-dependent CPT- and Lorentz-invariance violating coupling coefficients. We find 95% confidence intervals of Δa⊥<1.2×10−12  GeV and (−0.8<ΔaT−0.396ΔaZ<3.9)×10−13  GeV