On parton distributions beyond the leading order

The importance of properly taking into account the factorization scheme dependence of parton distribution functions is emphasized. A serious error in the usual handling of this topic is pointed out and the correct procedure for transforming parton distribution functions from one factorisation scheme to another recalled. It is shown that the conventional $\overline{\rm {MS}}$ and DIS definitions thereof are ill-defined due to the lack of distinction between the factorisation scheme dependence of parton distribution functions and renormalisation scheme dependence of the strong coupling constant $\alpha_s$. A novel definition of parton distribution functions is suggested and its role in the construction of consistent next-to-leading order event generators briefly outlined.Comment: PRA-HEP-93/05, Latex, 10 pages and 2 Postscript figures appended at the end of this fil

Measurement of the ratio of the ppˉ→Wp\bar{p}\to W+cc-jet cross section to the inclusive ppˉ→Wp\bar{p}\to W+jets cross section

We present a measurement of the fraction of inclusive $W$+jets events produced with net charm quantum number $\pm1$, denoted $W$+$c$-jet, in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using approximately 1~fb$^{-1}$ of data collected by the D0 detector at the Fermilab Tevatron Collider. We identify the $W$+jets events via the leptonic $W$ boson decays. Candidate $W$+$c$-jet events are selected by requiring a jet containing a muon in association with a reconstructed $W$ boson and exploiting the charge correlation between this muon and $W$ boson decay lepton to perform a nearly model-independent background subtraction. We measure the fraction of $W$+$c$-jet events in the inclusive $W$+jets sample for jet $p_{T}>20$ GeV and pseudorapidity $|\eta|<2.5$ to be 0.074$\pm0.019$(stat.)$\pm^{0.012}_{0.014}$(syst.), in agreement with theoretical predictions. The probability that background fluctuations could produce the observed fraction of $W$+$c$-jet events is estimated to be $2.5\times 10^{-4}$, which corresponds to a 3.5 $\sigma$ statistical significance.Comment: submitted to Physics Letters

FIRST SEARCHES FOR OPTICAL COUNTERPARTS TO GRAVITATIONAL-WAVE CANDIDATE EVENTS

During the LIGO and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type

Psychiatry and military conscription in Brazil: the search for opportunity and institutionalized therapy.

Since the fall of the Brazilian military dictatorship in 1984, a number of structural and ideological changes associated with demilitarization and democracy have changed the face of psychiatric theory and practice. Around the country, pockets of innovative, politically sensitive and Marxist-inspired community-based forms of "psi" practice are developing. This emergent psi movement is making a range of positive contributions to the lives of average citizens, including those of poor disenfranchized youth. This paper, however, explores one particular dimension of the work of psi practitioners that has proven antithetical to the psi community's current politicized community-based aims. Based on qualitative and quantitative longitudinal ethnographic fieldwork with therapists and young men in Pelotas, this paper analyzes how certain kinds of psi interventions being carried out in schools for a subset of lower-class young men during their early teen years are encouraging some youth to seek military training as a life option. Although these young men initially had quite captivating, engaged and politicized-if also conflicting-interactions with therapists, their eventual disillusionment with their therapeutic and scholastic experiences resulted in high levels of social alienation and de-politicization. In these young men's search for what can best be described as formulaic solutions to troubling psychological experiences associated with a tumultuous institutionalized transition to adulthood, military training came to represent a form of self-cultivation and self-therapy. Several youth also hoped military training would enable them to actively disengage with local political processes and find shelter from troubling social inequities and injustice. The paper ends by reviewing the implications of these results for the future of psi knowledge and practice in Brazil