Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Combined Tevatron upper limit on gg->H->W+W- and constraints on the Higgs boson mass in fourth-generation fermion models

Report number: FERMILAB-PUB-10-125-EWe combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg->H->W+W- in p=pbar collisions at the Fermilab Tevatron Collider at sqrt{s}=1.96 TeV. With 4.8 fb-1 of integrated luminosity analyzed at CDF and 5.4 fb-1 at D0, the 95% Confidence Level upper limit on \sigma(gg->H) x B(H->W+W-) is 1.75 pb at m_H=120 GeV, 0.38 pb at m_H=165 GeV, and 0.83 pb at m_H=200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, we exclude at the 95% Confidence Level a standard-model-like Higgs boson with a mass between 131 and 204 GeV.We combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg→H→W+W- in pp̅ collisions at the Fermilab Tevatron Collider at √s=1.96  TeV. With 4.8  fb-1 of integrated luminosity analyzed at CDF and 5.4  fb-1 at D0, the 95% confidence level upper limit on σ(gg→H)×B(H→W+W-) is 1.75 pb at mH=120  GeV, 0.38 pb at mH=165  GeV, and 0.83 pb at mH=200  GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, we exclude at the 95% confidence level a standard-model-like Higgs boson with a mass between 131 and 204 GeV.Peer reviewe

Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order

Demographic, clinical and antibody characteristics of patients with digital ulcers in systemic sclerosis: data from the DUO Registry

OBJECTIVES: The Digital Ulcers Outcome (DUO) Registry was designed to describe the clinical and antibody characteristics, disease course and outcomes of patients with digital ulcers associated with systemic sclerosis (SSc). METHODS: The DUO Registry is a European, prospective, multicentre, observational, registry of SSc patients with ongoing digital ulcer disease, irrespective of treatment regimen. Data collected included demographics, SSc duration, SSc subset, internal organ manifestations, autoantibodies, previous and ongoing interventions and complications related to digital ulcers. RESULTS: Up to 19 November 2010 a total of 2439 patients had enrolled into the registry. Most were classified as either limited cutaneous SSc (lcSSc; 52.2%) or diffuse cutaneous SSc (dcSSc; 36.9%). Digital ulcers developed earlier in patients with dcSSc compared with lcSSc. Almost all patients (95.7%) tested positive for antinuclear antibodies, 45.2% for anti-scleroderma-70 and 43.6% for anticentromere antibodies (ACA). The first digital ulcer in the anti-scleroderma-70-positive patient cohort occurred approximately 5 years earlier than the ACA-positive patient group. CONCLUSIONS: This study provides data from a large cohort of SSc patients with a history of digital ulcers. The early occurrence and high frequency of digital ulcer complications are especially seen in patients with dcSSc and/or anti-scleroderma-70 antibodies

P element temperature-specific transposition: a model for possible regulation of mobile elements activity by pre-mRNA secondary structure

P element is a DNA transposon, known to spread in genome using transposase activity. Its activity is tissue-specific and normally observed at high temperatures within 24°C to 29°C. Here, we present a predicted RNA secondary structure domain of P element pre-mRNA which could potentially regulate the temperature sensitivity of the P element activity. In canonical P elements, the structure is a small hairpin with double-helical part interrupted by a symmetric loop and a mismatch. In M type P elements, the A.A mismatch is substituted by an A-U base pair, stabilizing the structure. The hairpin structure covers the region involving the IVS-3 5′ splice site and both pseudo-splice sites F1 and F2. While the IVS-3 and F1 binding sites of U1 snRNA are located in the double-stranded part of the structure, the F2 site is exposed in the hairpin loop. The formation of this structure may interfere with landing of U1 snRNA on IVS-3 site, while F2 is positioned for the interaction. Alignment of P element sequences supports the proposed existence of the hairpin, showing high similarity for this region. The hairpin structure, stable at low temperatures, may prevent correct IVS-3 splicing. Conversely, temperature-induced destabilization of the hairpin structure may result in the splicing at the proper IVS-3 splice site. Taking into account the increasing amount of data demonstrating the important influence of RNA folding on phenotypes determined by alternative splicing a model for possible regulation of the activity of mobile elements by pre-mRNA secondary structure seems intriguing.Предсказана вторичная структура пре-мРНК P-элемента, которая, возможно, регулирует его активность и температурную чувствительность. Структура представляет собой шпильку, более стабильную в Р-элементах М-типа, в сравнении с каноническими. Регион, образующий шпильку, находится в области 5’ сайта сплайсинга третьего интрона (IVS-3), включая оба описанных псевдо-сайта сплайсинга - F1 и F2. В то время как истинный сайт и F1 расположены, главным образом, в двухцепочечной области шпильки, F2 - экспонирован в петле. Выравнивание последовательностей Р-элементов продемонстрировало высокую степень сходства для указанного региона, что свидетельствует в пользу существования предсказанной структуры. Формирование шпильки, по нашему мнению, может препятствовать связыванию U1 snRNA с истинным сайтом сплайсинга, и, напротив, индуцированная температурой дестабилизация шпильки может приводить к корректному сплайсингу IVS-3. Таким образом, предложена гипотеза о влиянии вторичной структуры пре-мРНК мобильного элемента на его активность.Передбачена вторинна структура пре-мРНК Р-елемента, що, можливо, регулює його активність та температурну чутливість. Структура являє собою шпильку, більш стабільну у Р-елементах М-типу, порівняно з канонічними. Регіон, що утворює шпильку розташований в області 5’ сайта сплайсинга третього інтрону (IVS-3), включає обидва відомих псевдо-сайта сплайсингу - F1 та F2. При цьому 5’ сайт сплайсингу IVS-3 та F1псевдо-сайт знаходяться у дволанцюговій частині шпильки, а F2 є єкспонованим у петлі. Вирівнювання послідовностей Р-елементів продемонструвало високий рівень подібності для вказаного регіону, що свідчить на користь існування передбаченої структури. Формування шпильки, на нашу думку, може перешкоджати зв’язуванню U1 snRNA з 5’ сайтом сплайсингу IVS-3, і, навпаки, індукована температурою дестабілізація шпильки може сприяти корректному сплайсингу третього інтрону. Таким чином, запропонована гіпотеза про вплив вторинної структури пре-мРНК мобільного елементу на його активність