Rare two-body decays of the top quark into a bottom meson plus an up or charm quark

Rare two-body decays of the top quark into a neutral bottom-quark meson plus an up- or charm-quark: $t\to {\overline B}^0+ u, c$; $t\to {\overline B}^0_{s}+ c,u$; and $t \to \Upsilon(nS)+ c,u$, are studied for the first time. The corresponding partials widths are computed at leading order in the non-relativistic QCD framework. The sums of all two-body branching ratios amount to $\mathcal{B}(t \to {\overline B}^0+ {\rm jet}) \approx \mathcal{B}(t \to {\overline B}^0_{s}+ {\rm jet}) \approx 4.2\cdot 10^{-5}$ and $\mathcal{B}(t \to \Upsilon(nS)+ {\rm jet}) \approx 2\cdot 10^{-9}$, respectively. The feasibility to observe the $t\to {\overline B}^0_{(s)}+{\rm jet}$ decay is estimated in top-pair events produced in proton-proton collisions at $\sqrt{s} = 14, 100$ TeV at the LHC and FCC, respectively. Combining many exclusive hadronic ${\overline B}^0_{(s)}$ decays, with $J/\psi$ or $D^{0,\pm}$ final states, about 50 (16000) events are expected in 3 (20) ab$^{-1}$ of integrated luminosity at the LHC (FCC), after typical selection criteria, acceptance, and efficiency losses. An observation of the two-body top-quark decay can also be achieved in the interesting $t\to b(\rm{jet})+c(\rm{jet})$ dijet final state, where the ${\overline B}^0_{(s)}$ decay products are reconstructed as a jet, with 5300 and 1.4 million signal events above backgrounds expected after selection criteria at the LHC and FCC, respectively. Such unique final states provide a new direct method to precisely measure the top-quark mass via simple 2-body invariant mass analyses.Comment: 26 pages, 5 figure

Surviving success : policy reform and the future of industrial pollution in China

China's recent industrial growth, a remarkable success story, has been clouded by hundreds of thousands of premature deaths and incidents of serious respiratory illness caused by exposure to industrial air pollution. Seriously contaminated by industrial discharges, many of China's waterways are largely unfit for direct human use. This damage could be substantially reduced at modest cost. Industrial reform combined with stricter environmental regulation has reduced organic water pollution in many areas and has curbed the growth of air pollution. But much higher levels of emissions controls (of particulates and sulfur dioxide) are warranted in China's polluted cities. For the cost-benefit analysis that led to this conclusion, the authors developed threescenarios projecting pollution damage under varying assumptions about future policies. Their findings are: Even if regulation is not tightened further, continued economic reform should have a powerful effect on pollution intensity. Organic water pollution will stabilize in many areas and actually decline in some. Air pollution will continue growing in most areas but at a much slower pace than industrial output. The cost of inaction would be high--most of China's waterways will remain heavily polluted, and many thousands of people will die or suffer serious respiratory damage. Continuing current trends in tightened regulation for water pollution will lead to sharp improvements; adopting an economically feasible policy of much stricter regulation will restore the health of many waterways. The stakes are even higher for air pollution because regulatory enforcement has weakened in many areas in the past five years. Reversing that trend will save many lives at extremely modest cost. China's National Environmental Protection Agency (NEPA) has recommended a tenfold increase in the air pollution levy; adopting NEPA's very conservative recommendation would produce a major turnaround in most cities. For representative Chinese cities, a fiftyfold increase in the levy is probably warranted economically. To be cost-effective, heavy sources of particulate and sulfur dioxide emissions should be targeted for abatement. Reducing emissions from large private plants is so cheap that only significant abatement makes sense -- at least 70 percent abatement of sulfur dioxide particulates and even greater abatement of particulates in large urban industrial facilities.Public Health Promotion,Water and Industry,Environmental Economics&Policies,Pollution Management&Control,Sanitation and Sewerage,Water and Industry,Environmental Economics&Policies,Health Monitoring&Evaluation,Pollution Management&Control,TF030632-DANISH CTF - FY05 (DAC PART COUNTRIES GNP PER CAPITA BELOW USD 2,500/AL