e+e−→bbˉW+W−e^+e^- \to b\bar b W^+W^- events at the Next Linear Collider: colour structure of top signal and irreducible background

We examine the colour structure and charged particle yield for both the $t \bar t$ signal and the irreducible background processes contributing to \eebbww\ production close to the \ttb\ threshold. The charged particle multiplicity for the various components of the cross section is computed as a function of several kinematic variables. Our study may have important implications for recently proposed studies of interconnection phenomena in \ttb\ production at high--energy $e^+e^-$ collidersComment: 14 pages, Latex, 8 figures uuencoded, complete ps file available via anonymous ftp at: ftp://axpc.hep.phy.cam.ac.uk/disk$alpha1:[public.hep9514]CAVENDISH_9514.ps http://www.hep.phy.cam.ac.uk/theory/papers/index.htm

Event shapes in e+e- annihilation and deep inelastic scattering

This article reviews the status of event-shape studies in e+e- annihilation and DIS. It includes discussions of perturbative calculations, of various approaches to modelling hadronisation and of comparisons to data.Comment: Invited topical review for J.Phys.G; 40 pages; revised version corrects some nomenclatur

Measurement of the B hadron lifetime at the SLC

We have measured the average B hadron lifetime from Z{sup 0} {r_arrow} b{bar b} events using the Mark II detector at the SLC. We use an impact parameter tag, requiring two or more tracks with significant impact parameter ({delta}) in a hemisphere, to obtain a 40% efficiency and an 80% B-purity. The {Sigma}{delta} distribution from charged tracks in the hemisphere opposite the tag is used to fit for {tau}{sub b}. From 53 tagged B decays we find {tau}{sub b} = 1.63{sub {minus}0.40}{sup +0.64}(stat) {plus_minus}0.16(syst) psec (preliminary), consistent with the world average. This method can be competitive with {tau}{sub b} measurements using high P{sub T} leptons and has a different sensitivity to {tau}(B{sup +})/{tau}(B{sup 0})

Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2

In this study, 36 cores (30 starless and 6 protostellar) identified in Orion were surveyed to search for inward motions. We used the Nobeyama 45 m radio telescope, and mapped the cores in the $J = 1\rightarrow0$ transitions of HCO$^+$, H$^{13}$CO$^+$, N$_2$H$^+$, HNC, and HN$^{13}$C. The asymmetry parameter $\delta V$, which was the ratio of the difference between the HCO$^+$ and H$^{13}$CO$^+$ peak velocities to the H$^{13}$CO$^+$ line width, was biased toward negative values, suggesting that inward motions were more dominant than outward motions. Three starless cores (10% of all starless cores surveyed) were identified as cores with blue-skewed line profiles (asymmetric profiles with more intense blue-shifted emission), and another two starless cores (7%) were identified as candidate blue-skewed line profiles. The peak velocity difference between HCO$^+$ and H$^{13}$CO$^+$ of them was up to 0.9 km s$^{-1}$, suggesting that some inward motions exceeded the speed of sound for the quiescent gas ($\sim10-17$ K). The mean of $\delta V$ of the five aforementioned starless cores was derived to be $-$0.5$\pm$0.3. One core, G211.16$-$19.33North3, observed using the ALMA ACA in DCO$^+$ $J = 3\rightarrow2$ exhibited blue-skewed features. Velocity offset in the blue-skewed line profile with a dip in the DCO$^+$ $J = 3\rightarrow2$ line was larger ($\sim 0.5$ km s$^{-1}$) than that in HCO$^+$ $J = 1\rightarrow0$ ($\sim 0.2$ km s$^{-1}$), which may represent gravitational acceleration of inward motions. It seems that this core is at the last stage in the starless phase, judging from the chemical evolution factor version 2.0 (CEF2.0).Comment: 45 pages, 28 figures, ApJ in pres

TWO PHOTON EXCITATION OF THE TENSOR MESON f0 (1270)

We have measured charged particle pair production in two-photon scattering at the e+e- storage ring PETRA. While the main source of such events is the production of lepton pairs, the presence of an additional process is clearly indicated by the measured invariant mass distribution of the two particles and their angular distributions. We determine that the excess is mainly due to the decay f0(1270)→π+π-. We derive a width Γ(f0→γγ)=3.2±0.2±0.6 keV (statistical and systematic). © 1981 Springer-Verlag