Factorization and Resummation for Dijet Invariant Mass Spectra

Multijet cross sections at the LHC and Tevatron are sensitive to several distinct kinematic energy scales. When measuring the dijet invariant mass m_jj between two signal jets produced in association with other jets or weak bosons, m_jj will typically be much smaller than the total partonic center-of-mass energy Q, but larger than the individual jet masses m, such that there can be a hierarchy of scales m << m_jj << Q. This situation arises in many new-physics analyses at the LHC, where the invariant mass between jets is used to gain access to the masses of new-physics particles in a decay chain. At present, the logarithms arising from such a hierarchy of kinematic scales can only be summed at the leading-logarithmic level provided by parton-shower programs. We construct an effective field theory, SCET+, which is an extension of soft-collinear effective theory that applies to this situation of hierarchical jets. It allows for a rigorous separation of different scales in a multiscale soft function and for a systematic resummation of logarithms of both m_jj/Q and m/Q. As an explicit example, we consider the invariant mass spectrum of the two closest jets in e+e- -> 3 jets. We also give the generalization to pp -> N jets plus leptons relevant for the LHC.Comment: 37 pages, 6 figures; v2: journal versio

Jet p_T Resummation in Higgs Production at NNLL'+NNLO

We present predictions for Higgs production via gluon fusion with a p_T veto on jets and with the resummation of jet-veto logarithms at NNLL'+$NNLO order. These results incorporate explicit O(alphas^2) calculations of soft and beam functions, which include the dominant dependence on the jet radius R. In particular the NNLL' order accounts for the correct boundary conditions for the N3LL resummation, for which the only unknown ingredients are higher-order anomalous dimensions. We use scale variations in a factorization theorem in both rapidity and virtuality space to estimate the perturbative uncertainties, accounting for both higher fixed-order corrections as well as higher-order towers of jet-p_T logarithms. This formalism also predicts the correlations in the theory uncertainty between the exclusive 0-jet and inclusive 1-jet bins. At the values of R used experimentally, there are important corrections due to jet algorithm clustering that include logarithms of R. Although we do not sum logarithms of R, we do include an explicit contribution in our uncertainty estimate to account for higher-order jet clustering logarithms. Precision predictions for this H+0-jet cross section and its theoretical uncertainty are an integral part of Higgs analyses that employ jet binning.Comment: 24 pages, 11 figure

Integration of geriatrics into a spiral undergraduate medical curriculum in Pakistan: evaluation and feedback of third-year medical students.

Background: In the last decades there has been a sharp rise in the elderly population throughout the world. The unique needs of the elderly require a multidisciplinary and comprehensive medical approach. None of the 50 medical schools in Pakistan teach geriatrics in their undergraduate or postgraduate training. This paper discusses the development and implementation of the first geriatric curriculum in a medical school of Pakistan and its effect on knowledge and attitudes of third-year medical students. Methods: The curriculum was designed through collaboration and approval of various academic departments at the Aga Khan University in Karachi Pakistan. After a review of existing geriatric curricula at other institutions, a problem-based, inter-disciplinary spiral curriculum was designed. Strategy of student and course evaluation was planned and incorporated in the curricular program. No extra resources or funds were used. A component of the new curriculum was assessed by evaluating pre- and post- course knowledge, and seeking feedback from participating third-year students. Results: A significant improvement in mean scores for summed overall knowledge in geriatrics (pre-test mean 4.7 vs. post-test mean 6.4, p value of of \u3c0.001; out of a maximum possible of 9 was noted. Breakdown of knowledge mean scores into component areas of knowledge showed a significant increase in understanding in aging demographics (pretest 0.7 vs. post-test 1.7, p value of \u3c0.001), geriatric history taking (pretest 0.64 vs. post-test 0.88, p 0.001) and geriatric assessments (pre- test 1.4 vs. post- test 1.7,p value 0.01). A strong majority (87%) of the students felt that the overall course objectives were achieved. All students were satisfied with the quality of teaching, 90% rating it good or higher. Conclusion: An important advance in medical education was achieved via integration of a low cost, spiral geriatrics curriculum in a medical university of Pakistan. We found that introduction of the geriatric curriculum improved the knowledge of third-year medical students. This was our school\u27s initial step towards building professional capacity in response to a rising elderly population

An architecture for reliable distributed computer-controlled systems

In Distributed Computer-Controlled Systems (DCCS), both real-time and reliability requirements are of major concern. Architectures for DCCS must be designed considering the integration of processing nodes and the underlying communication infrastructure. Such integration must be provided by appropriate software support services. In this paper, an architecture for DCCS is presented, its structure is outlined, and the services provided by the support software are presented. These are considered in order to guarantee the real-time and reliability requirements placed by current and future systems

De novo SCN1A mutations in Dravet syndrome and related epileptic encephalopathies are largely of paternal origin

Background: Dravet syndrome is a severe infantile epileptic encephalopathy caused in approximately 80% of cases by mutations in the voltage gated sodium channel subunit gene SCN1A. The majority of these mutations are de novo. The parental origin of de novo mutations varies widely among genetic disorders and the aim of this study was to determine this for Dravet syndrome. Methods: 91 patients with de novo SCN1A mutations and their parents were genotyped for single nucleotide polymorphisms (SNPs) in the region surrounding their mutation. Allele specific polymerase chain reaction (PCR) based on informative SNPs was used to separately amplify and sequence the paternal and maternal alleles to determine in which parental chromosome the mutation arose. Results: The parental origin of SCN1A mutations was established in 44 patients for whom both parents were available and SNPs were informative. The mutations were of paternal origin in 33 cases and of maternal origin in the remaining 11 cases. De novo mutation of SCN1A most commonly, but not exclusively, originates from the paternal chromosome. The average age of parents originating mutations did not differ from that of the general population. Conclusions: The greater frequency of paternally derived mutations in SCN1A is likely to be due to the greater chance of mutational events during the increased number of mitoses which occur during spermatogenesis compared to oogenesis, and the greater susceptibility to mutagenesis of the methylated DNA characteristic of sperm cells.Sarah E. Heron, Ingrid E. Scheffer, Xenia Iona, Sameer M. Zuberi, Rachael Birch, Jacinta M. McMahon, Carla M. Bruce, Samuel F. Berkovic, John C. Mulle