3,159 research outputs found

    Recent results on charm from E831-FOCUS

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    E831-FOCUS is a photoproduction experiment which collected data during the 1996/1997 fixed target run at Fermilab. More than 1 million charm particles have been reconstructed. Using this sample we measure the lifetimes of all the weakly decaying singly charmed particles, establishing the charm lifetime hierachy. Then we present recent results on semileptonic decays of charm mesons, including the new s-wave inteference phenomena in D+ to K-pi+mu+nu, and high statistics branching ratio and form factor measurements.Comment: Invited talk at the Workshop on the CKM Unitarity Triangle, IPPP Durham, April 2003 (eConf C0304052). 4 pages LaTeX, 2 eps figure

    Charm Hadronic Decays From FOCUS: Lessons Learnt

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    The FOCUS photoproduction experiment took data in the ninenties and produced a wealth of results in charm physics. Some of the studies were seminal for contemporary experiments, and even paved the way for the technology of many charm and beauty analysis tools.Comment: Presented by S.Bianco at CHARM2010, IHEP Beijing. Six pages, 2 figure

    Search for the flavour-changing neutral current decay D0 to mu+mu- in pp collisions at sqrt(s) = 7 TeV with CMS

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    A search for the flavour-changing neutral current decay D0 to mu+mu- is performed in pp collisions at sqrt(s) = 7 TeV using 90 pb-1 of data collected by the CMS experiment at the LHC. No evidence is found for this decay mode. The upper limit on the branching fraction B(D0 to mu+mu-) is 5.4x10-7 at the 90% confidence level.Comment: to appear in the proceedings of The 5th International Workshop on Charm Physics (Charm 2012

    A study on the possible merits of using symptomatic cases to trace the development of the COVID-19 pandemic

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    In a recent work we introduced a novel method to compute the effective reproduction number RtR_t and we applied it to describe the development of the COVID-19 outbreak in Italy. The study is based on the number of daily positive swabs as reported by the Italian Dipartimento di Protezione Civile. Recently, the Italian Istituto Superiore di Sanit\`a made available the data relative of the symptomatic cases, where the reporting date is the date of beginning of symptoms instead of the date of the reporting of the positive swab. In this paper we will discuss merits and drawbacks of this data, quantitatively comparing the quality of the pandemic indicators computed with the two samples

    A simplified estimate of the Effective Reproduction Number RtR_t using its relation with the doubling time and application to Italian COVID-19 data

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    A simplified method to compute RtR_t, the Effective Reproduction Number, is presented. The method relates the value of RtR_t to the estimation of the doubling time performed with a local exponential fit. The condition Rt=1R_t = 1 corresponds to a growth rate equal to zero or equivalently an infinite doubling time. Different assumptions on the probability distribution of the generation time are considered. A simple analytical solution is presented in case the generation time follows a gamma distribution.Comment: Submitted to: The European Physical Journal Plus. Revised version according to reviewer's comment

    Nonleptonic Decays and Lifetimes of b-quark and c-quark Hadrons

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    We review recent experimental results on lifetimes and hadronic decays of hadrons that contain cc and bb quarks. The theoretical implications of these results are also considered. An understanding of hadronic decays of heavy quarks is required to interpret the CP violating asymmetries in BB decays that will be observed in experiments planned for the near future.Comment: 74 pages, LATEX format with 12 figures. To appear in Annual Review of Nuclear and Particle Science, Vol. 46. Also available at http://www-physics.mps.ohio-state.edu/~phys111/b-physics/bphysics.html and by anonymous ftp from ftp://pacific.mps.ohio-state.edu/pub/hepex/kh A serious typographical error on p. 8 is corrected. Other errors and typos are also correcte

    A statistical analysis of death rates in Italy for the years 2015-2020 and a comparison with the casualties reported for the COVID-19 pandemic

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    We analyze the data about casualties in Italy in the period 01/01/2015 to 30/09/2020 released by the Italian National Institute of Statistics (ISTAT). The data exhibit a clear sinusoidal behavior, whose fit allows for a robust subtraction of the baseline trend of casualties in Italy, with a surplus of mortality in correspondence to the flu epidemics in winter and to the hottest periods in summer. While these peaks are symmetric in shape, the peak in coincidence with the COVID-19 pandemics is asymmetric and more pronounced. We fit the former with a Gaussian function and the latter with a Gompertz function, in order to quantify number of casualties, the duration and the position of all causes of excess deaths. The overall quality of the fit to the data turns out to be very good. We discuss the trend of casualties in Italy by different classes of ages and for the different genders. We finally compare the data-subtracted casualties as reported by ISTAT with those reported by the Italian Department for Civil Protection (DPC) relative to the deaths directly attributed to COVID-19, and we discuss the differences.Comment: 16 pages, 13 figure
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