Sneha Malde

Abstract:

DØ has measured the inclusive production cross section of W and Z bosons in a sample of 13 pb^-1 of data collected at the Fermilab Tevatron. The cross sections, multiplied by their leptonic branching fractions, for production in pp̄ collisions at √s=1.8 TeV are σWB(W→eν)=2.36±0.02±0.08±0.13 nb, σWB(W →μν)=2.09±0.06±0.22±0.11 nb, σZB(Z→e⁺e ^-)=0.218±0.008±0.008±0.012 nb, and σZB(Z →μ⁺μ ^-)=0.178±0.022±0.021±0.009 nb, where the first uncertainty is statistical and the second systematic; the third reflects the uncertainty in the integrated luminosity. For the combined electron and muon analyses, we find σWB(W→lν)/σZB(Z→l ⁺l^-)=10.90±0.52. Assuming standard model couplings, we use this result to determine the width of the W boson, and obtain Γ(W)=2.044±0.097 GeV. ©1999 The American Physical Society.

Abstract:

We report measurements of the D⁰, D⁺, and D⁺ s meson lifetimes using 3.7fb^-1 of e⁺e^- annihilation data collected near the ϒ(4S) resonance with the CLEO detector. The measured lifetimes of the D⁰, D⁺, and D⁺ s mesons are 408.5 ± 4.1^+3.5 -3.4 fs, 1033.6 ± 22.1^+9.9 -12.7 fs, and 486.3 ± 15.0^+4.9 -5.1 fs. The precisions of these lifetimes are comparable to those of the best previous measurements, and the systematic errors are very different. In a single experiment we find that the ratio of the D⁺ s and D⁰ lifetimes is 1.19 ± 0.04. © 1999 The American Physical Society.

Abstract:

We present a measurement of the time-dependent asymmetry in the rate for B^-0 d versus B⁰ d decays to J/ψK⁰ S. A nonzero asymmetry would be an indication of CP violation, and within the standard model this may be used to measure the CP-violation parameter sin(2β)2. A total of 198 ± 17 B⁰ d/B¯⁰ d decays were observed in 99¯ collisions at √s = 1.8 TeV by the CDF detector at the Fermilab Tevatron. B⁰ d and B¯⁰ d are distinguished by a technique based on charge correlations from hadronization of the b quark. Our analysis results in sin(2β) = 1.8 ± 1.1(stat) ± 0.3(syst). © 1998 The American Physical Society.

Abstract:

As measurements of the CKM angle $\gamma$ in decays of $b$-hadrons become increasingly precise, it is important to consider the impact of processes that affect secondary and tertiary decay products and can contribute to the observed CP violation. The golden decay mode used to measure $\gamma$ is $B^\pm\to DK^\pm$, where $D\to K_\text{S}^0\pi^+\pi^-$. Due to the presence of a $K_\text{S}^0$ meson in the final state, $\gamma$ measurements based on this mode are affected by neutral kaon CP violation and matter regeneration, and this study examines the potential size of the impact. Previous studies determine the impact of kaon CP violation to be a few degrees in size, but make simplifying assumptions about how experimental measurements are implemented. These assumptions are lifted in the present study, and the matter regeneration effect is included for the first time. The results are presented within the context of $\gamma$ measurements to be made using the LHCb and Belle II II detectors. It is found that the expected biases due to ignoring the effects of CP violation and matter regeneration in neutral kaons is small and less than $0.5^\circ$ degrees in all experimental scenarios considered.