Heavy Flavour Production

We review the status of heavy flavour production in QCD. Comparison of experimental and theoretical results for top and bottom production are given. Selected topics in charm production are also discussed.Comment: 18 pages, Latex, epsfig, 12 tar-gzip-uuencoded figures. Invited talk given at the XV International conference "Physics in Collisions", Cracow, Poland, June 8-10, 199

NLO Higgs boson production via gluon fusion matched with shower in POWHEG

We present a next-to-leading order calculation of Higgs boson production via gluon fusion interfaced to shower Monte Carlo programs, implemented according to the POWHEG method. A detailed comparison with MC@NLO and PYTHIA is carried out for several observables, for the Tevatron and LHC colliders. Comparisons with next-to-next-to-leading order results and with resummed ones are also presented.Comment: Version accepted for publication by JHEP. One more figure added to Sec 4.1.2 and two more explanatory figures and comments added to Sec 4.3 on p_T distribution

Is There a Significant Excess in Bottom Hadroproduction at the Tevatron?

We discuss the excess in the hadroproduction of B mesons at the Tevatron. We show that an accurate use of up-to-date information on the B fragmentation function reduces the observed excess to an acceptable level. Possible implications for experimental results reporting bottom quark cross sections, also showing an excess with respect to next-to-leading order theoretical predictions, are discussed.Comment: 5 pages, Latex, 4 figures. Submitted to Phys. Rev. Let

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A Positive-Weight Next-to-Leading-Order Monte Carlo for Heavy Flavour Hadroproduction

We present a next-to-leading order calculation of heavy flavour production in hadronic collisions that can be interfaced to shower Monte Carlo programs. The calculation is performed in the context of the POWHEG method. It is suitable for the computation of charm, bottom and top hadroproduction. In the case of top production, spin correlations in the decay products are taken into account.Comment: 18 pages, 12 figures. Few misprints corrected, references updated, final remarks adde

COVID-19 cycles and rapidly evaluating lockdown strategies using spectral analysis.

Spectral analysis characterises oscillatory time series behaviours such as cycles, but accurate estimation requires reasonable numbers of observations. At the time of writing, COVID-19 time series for many countries are short: pre- and post-lockdown series are shorter still. Accurate estimation of potentially interesting cycles seems beyond reach with such short series. We solve the problem of obtaining accurate estimates from short series by using recent Bayesian spectral fusion methods. Weshow that transformed daily COVID-19 cases for many countries generally contain three cycles operating at wavelengths of around 2.7, 4.1 and 6.7 days (weekly) and that shorter wavelength cycles are suppressed after lockdown. The pre- and post-lockdown differences suggest that the weekly effect is at least partly due to non-epidemic factors. Unconstrained, new cases grow exponentially, but the internal cyclic structure causes periodic declines. This suggests that lockdown success might only be indicated by four or more daily falls. Spectral learning for epidemic time series contributes to the understanding of the epidemic process and can help evaluate interventions. Spectral fusion is a general technique that can fuse spectra recorded at different sampling rates, which can be applied to a wide range of time series from many disciplines

Common trends and common cycles in Canada: who knew so much has been going on?

It is generally accepted that convergence is well established for regional Canadian per capita outputs. The authors present evidence that long-run movements are driven by two stochastic common trends in this time series. This evidence casts doubt on the convergence hypothesis for Canada. Another prevalent belief is that Canada forms an optimal currency area (OCA). The authors uncover three serially correlated common cycles whose asymmetries suggest Canada is not an OCA. Their common trend-common cycle decomposition of regional outputs also reveals that trend shocks dominate fluctuations in Ontario, Quebec, and the Maritimes in the short run and long run but not in British Columbia and the Prairie region. Thus, regional Canadian economic fluctuations are driven by a rich, diverse, and economically important set of propagation and growth mechanisms.

Bulk commodities and the Liverpool and London markets of the mid-19th century

We study British prices and the degree of commodity market integration between Liverpool, the bulk commodity port of mid-19th century, and London. A new wholesale commodity price index is presented for Liverpool and this is compared with the Klovland-Sauerbeck index. Next, we examine the relationship between Liverpool and London markets in specific bulk commodities. Our data consist of price indices for identically described goods in both Liverpool and London: three commodity groups (metal products, wood products, and processed foods), and the specific commodities of wheat and flour. Tests for cointegration reveal convergence among the six price pairs. We also find that the markets were highly integrated in the short-run because three of the commodity group pairs (processed foods, wheat, and flour) shared common features or cycles. A common cycle implies that transitory price shocks in Liverpool had the same impact on prices in London and vice versa. The importance of the London and Liverpool common cycle to a shock is brief. Its shock explains less than 20 percent of the variation in the relevant price levels after twelve months, on average.

A Positive-Weight Next-to-Leading-Order Monte Carlo for Z Pair Hadroproduction

We present a first application of a previously published method for the computation of QCD processes that is accurate at next-to-leading order, and that can be interfaced consistently to standard shower Monte Carlo programs. We have considered Z pair production in hadron-hadron collisions, a process whose complexity is sufficient to test the general applicability of the method. We have interfaced our result to the HERWIG and PYTHIA shower Monte Carlo programs. Previous work on next-to-leading order corrections in a shower Monte Carlo (the MC@NLO program) may involve the generation of events with negative weights, that are avoided with the present method. We have compared our results with those obtained with MC@NLO, and found remarkable consistency. Our method can also be used as a standalone, alternative implementation of QCD corrections, with the advantage of positivity, improved convergence, and next-to-leading logarithmic accuracy in the region of small transverse momentum of the radiated parton.Comment: 33 pages, 10 figure