A Comparison of two different jet algorithms for the top mass reconstruction at the LHC

We compare the abilities of the cluster-type jet algorithm, KtJet, and a mid-point iterating cone algorithm to reconstruct the top mass at the LHC. We discuss the information contained in the merging scales of cluster-type algorithms, and how this can be used in experimental analyses, as well as the different sources of systematic errors for the two algorithms. We find that the sources of systematic error are different for the two algorithms, which may help to better constrain the systematic error on the top mass at the LHC.Comment: 21 pages, 16 figures, accepted by JHE

РОБОТ-АССИСТИРОВАННАЯ ЛАПАРОСКОПИЧЕСКАЯ ПРОСТАТЭКТОМИЯ: НАШ ОПЫТ

Background. Retropubic radical prostatectomy (RPE) is now the gold standard of treatment for locally advanced prostate cancer (PC). However, robot-assisted RPE procedures using the da Vinci system are finding increasing acceptance.Materials and methods. The authors conducted a prospective study of 60 robot-assisted prostatectomies made at the Clinic of Urology, N.I. Pirogov National Medical Surgical Center, in the period January 2009 to December 2010.Results. The duration of an operation averaged 230 min; the average amount of blood loss was 200 ml. The mean duration of postoperative analgesia was 2,7 days. That of urinary catheterization was 8.5 days. A normal postoperative course was noted in most cases (88,4 %). Seven patients were found to have 8 (13,3 %) mild and moderate complications. A pathohistological study revealed a positive surgical margin of resection in 21,7 % of the patients, extracapsular tumor growth in 21,7 %, and seminal vesicle invasion in 23,3 %. Tumor-affected regional lymph nodes were detected in 1 (1,7 %) patient. In our observed series, 82 and 93 % of the subjects completely retained urine after 6 and 12 moths, respectively. Throughout the follow-up, erectile function recovered in 7 of the 15 patients undergoing a nerve-sparing surgical procedure.Conclusion. Postoperative results in our series of interventions are comparable to those obtained in the studies by Russian and foreign colleagues at the early stage of mastering this procedure. By considering a few observations, it is today difficult to say that our study is valid in the context of evidence-based medicine. Estimation of the benefits of robot-assisted laparoscopic prostatectomy calls for long-term multicenter randomized trials.Введение. Позадилонная радикальная простатэктомия (РПЭ) является в настоящее время «золотым стандартом» в лечении локализованных форм рака предстательной железы (РПЖ). Однако все большее распространение получают робот-ассистированные методики выполнения РПЭ, осуществляемые при помощи системы da Vinci.Материалы и методы. Мы провели проспективное исследование 60 робот-ассистированных простатэктомий, выполненных в период с января 2009 по декабрь 2010 г. в клинике урологии НМХЦ им. Н.И. Пирогова.Результаты. Длительность операции составила в среднем 230 мин, средняя величина кровопотери — 200 мл. Средняя продолжительность послеоперационной анальгезии составила 2,7 сут. Длительность катетеризации мочевого пузыря в среднем составила 8,5 сут. В большинстве наблюдений (88,4 %) отмечено гладкое послеоперационное течение. У 7 пациентов было выявлено 8 (13,3 %) осложнений легкой и средней степени тяжести. При патогистологическом исследовании положительный хирургический край резекции определен у 21,7 % пациентов, экстракапсулярный рост опухоли — у 21,7 %, инвазия в семенные пузырьки — у 23,3 % наблюдаемых. Поражение опухолью регионарных лимфатических узлов выявлено у 1 (1,7 %) пациента. В нашей серии через 6 мес полностью удерживали мочу 82 % наблюдаемых, через 12 мес — 93 %. За весь период наблюдения эректильная функция восстановилась у 7 из 15 пациентов, подвергнутых нервосохраняющей методике операции.Заключение. Послеоперационные показатели проведенной нами серии вмешательств сопоставимы с результатами исследований отечественных и зарубежных коллег на раннем этапе освоения метода. С учетом небольшого количества наблюдений говорить о достоверности нашего исследования с позиции доказательной медицины пока сложно. Оценка преимуществ роботассистированной лапароскопической простатэктомии требует проведения долгосрочных многоцентровых рандомизированных исследований

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of s√=7TeV proton-proton collisions

Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurement of the production cross section for W-bosons in association with jets in pp collisions at s=7 TeV with the ATLAS detector

This Letter reports on a first measurement of the inclusive W + jets cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC, with the ATLAS detector. Cross sections, in both the electron and muon decay modes of the W-boson, are presented as a function of jet multiplicity and of the transverse momentum of the leading and next-to-leading jets in the event. Measurements are also presented of the ratio of cross sections sigma (W + >= n)/sigma(W + >= n - 1) for inclusive jet multiplicities n = 1-4. The results, based on an integrated luminosity of 1.3 pb(-1), have been corrected for all known detector effects and are quoted in a limited and well-defined range of jet and lepton kinematics. The measured cross sections are compared to particle-level predictions based on perturbative QCD. Next-to-leading order calculations, studied here for n <= 2, are found in good agreement with the data. Leading-order multiparton event generators, normalized to the NNLO total cross section, describe the data well for all measured jet multiplicitie

Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

A measurement of the production cross-section for top quark pairs(\ttbar) in $pp$ collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron $e$ or muon $\mu$) with large missing transverse energy and at least four jets, and dilepton ($ee$, $\mu\mu$ or $e\mu$) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be $12.2 \pm 3.9$ events and $2.5 \pm 0.6$ events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of √s=7 TeV proton-proton collisions

Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV