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

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

Search for the standard model Higgs boson in the diphoton decay channel with 4.9fb -1 of pp collision data at √s=7TeV with atlas

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9  fb-1 collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7  TeV. In the diphoton mass range 110–150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110–150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113–115 GeV and 134.5–136 GeV

Search for the standard model Higgs boson in the diphoton decay channel with 4.9fb -1 of pp collision data at √s=7TeV with atlas

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9  fb-1 collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7  TeV. In the diphoton mass range 110–150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110–150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113–115 GeV and 134.5–136 GeV

Untersuchung der Lebensqualität nach chirurgischer Versorgung der angeborenen und erworbenen Ringbandstenose

Background: Evaluation of quality of life following surgical release of the first annular flexor tendon pulley in children suffering from pediatric trigger thumb in comparison to adult patients with trigger finger.Material and methods: All patients who underwent an A1 tendon pulley release between 2006 and 2010 at a hand surgery center were reviewed retrospectively. Chart review included operation type, length of hospital stay, and type of anesthesia. Patient satisfaction was assessed using two validated hand questionnaires, the Disabilities of the Arm, Shoulder and Hand (DASH) Outcome Measure and the German Michigan Hand Outcomes Questionnaire (MHQ).Results: A total of 13 children and 147 adults were included in the study. No postoperative complications or recurrence were observed in the pediatric patient population. Postoperative DASH score in children was 0±0 and in adults 14±2. Postoperative German MHQ score was 97±3 in children and 84±2 in adults. Patient satisfaction was rated positive in all children and in 87% of adults; all children and 93% of the adults would undergo this procedure again. Conclusions: The surgical release of the A1 pulley in children and adults is a safe and low-risk procedure. Postoperative quality of life, especially in children, is high; patients and parents were highly satisfied. Therefore, the surgical approach should be recommended as a first-line treatment of the trigger finger in all age groups.Hintergrund: Evaluation der Lebensqualität nach chirurgischer Ringbandspaltung bei angeborener Ringbandstenose des Daumens bei Kindern (Pollex flexus congenitus) sowie erworbener Ringbandstenose bei Erwachsenen. Material und Methoden: Retrospektiv wurden allgemeine Patientendaten nach offener Ringbandspaltung zwischen 2006 und 2010 sowie die Patientenzufriedenheit mit den Patienten-orientierten Fragebögen Michigan Hand Outcomes Questionnaire (MHQ) und Disabilities of the Arm, Shoulder and Hand (DASH) Outcome Measure ausgewertet und analysiert. Ergebnisse: 13 Kinder und 147 erwachsene Patienten wurden in die Studie aufgenommen. Postoperativ kam es bei den Kindern zu keinen Komplikationen oder dem Wiederauftreten eines Schnappphänomens des Daumens. Der postoperative DASH-Score der Kinder war 0±0 Punkte und bei den Erwachsenen 14±2. Der postoperative MHQ-Score lag bei den Kindern bei 97±3 Punkten, der der Erwachsenen bei 84±2. Die postoperative Zufriedenheit wurde bei allen Kindern und bei 87% der erwachsenen Patienten als positiv gewertet. Alle Kinder sowie 93% der Erwachsenen würden sich erneut diesem operativen Eingriff unterziehen. Schlussfolgerung: Die chirurgische Intervention zur Behandlung des Pollex flexus congenitus bei Kindern sowie der Ringbandstenose bei Erwachsenen ist ein sicherer und risikoarmer Eingriff. Die postoperative Lebensqualität, speziell die der Kinder, ist hoch. Daher kann das chirurgische Vorgehen als First-Line-Therapie beim schnellenden Finger in allen Altersgruppen empfohlen werden

Analyse der Lebensqualität nach chirurgischer Spaltung des ersten Strecksehnenfachs bei Tendovaginitis stenosans de Quervain

Background: Evaluation of the quality of life following surgical release of the first extensor compartment in adult patients with de Quervain disease. Patients and methods: This retrospective study included hospital chart review and patient-reported outcome assessment using the German version of the Disabilities of the Arm, Shoulder and Hand (DASH) Outcome Measure and the validated German Michigan Hand Outcomes Questionnaire (MHQ). Results: A total of 46 patients underwent a surgical release of the first extensor compartment for de Quervain disease. Postoperative German MHQ was 78±4. Postoperative DASH score was 19±5. Satisfaction with surgery was rated positive in 85%, and 89% would undergo the procedure again. Patients with a transversal incision line had a DASH result of 11±6 and a German MHQ score of 83±7, patients with a longitudinal incision had a DASH score of 22±9 and a German MHQ score of 80±6. The patients pain level after transversal incision was markedly lower (resting pain=0.4±0.3; stress pain=1.0±0.6) than in patients operated with a longitudinal incision (resting pain=2.4±0.9; stress pain=3.1±1.1). Conclusion: The surgical approach for the treatment of de Quervain disease is associated with a high postoperative quality of life, a low postoperative morbidity and a low level of postoperative pain. A transversal incision is associated with better postoperative results than the longitudinal approach.Hintergrund: Die Zufriedenheit von Patienten nach chirurgischer Spaltung des ersten Strecksehnenfaches bei De Quervain Tendinopathie ist unbekannt. Aufgrund der weiten Verbreitung dieser ambulanten Operation stellten wir uns die Frage, wie sich die Lebensqualität nach offen chirurgischer Spaltung des ersten Strecksehnenfaches bei erwachsenen Patienten mit einer Tendovaginitis stenosans de Quervain verhält. Patienten und Methoden: Retrospektiv wurden Patientendaten sowie die Patienten-orientierten Fragebögen Michigan Hand Outcomes Questionnaire (MHQ) und Disabilities of the Arm, Shoulder and Hand (DASH) Outcome Measure ausgewertet und analysiert. Primäre Endpunkte: DASH-Ergebnis (0=keine Einschränkung, 100=maximale Einschränkung) und MHQ-Ergebnis (0=maximale Einschränkung, 100=keine Einschränkung), sekundäre Endpunkte: Schmerzen (Numerische Rating Skala (NRS) 0-10), Zufriedenheit, Narkoseform, Schnittführung, Komplikationen. Ergebnisse: Wir führten bei insgesamt 46 Patienten eine offen chirurgische Spaltung des ersten Strecksehnenfachs durch. Der postoperative MHQ-Score war 78±4 Punkte und der postoperative DASH-Score 19±5 Punkte. Die Zufriedenheit der Patienten mit dem chirurgischen Vorgehen lag bei 85%, wobei sich 89% dieser Prozedur erneut unterziehen würden. Patienten mit einer quer zum Handgelenk verlaufenden Hautschnittführung hatten einen MHQ-Score von 83±7 Punkten und einen DASH-Score von 11±6 Punkten, während Patienten mit einer Längsinzision einen MHQ-Score von 80±6 Punkten und einen DASH-Score von 22±9 Punkten aufwiesen (n.s.). Das Schmerzniveau nach querer Schnittführung (Ruheschmerz=0,4±0,3; Belastungsschmerz= 1,0±0,6) war deutlich geringer als bei Patienten mit longitudinaler Inzision (Ruheschmerz=2,4±0,9; Belastungsschmerz=3,1±1,1, n.s.). Schlussfolgerung: Die offen chirurgische Spaltung des ersten Strecksehnenfaches bei Tendovaginitis de Quervain ist mit einer hohen postoperativen Lebensqualität, einer geringen Morbidität sowie einem niedrigen Grad an postoperativen Schmerzen verbunden. Die quere Inzision zeigte zudem bessere postoperative Ergebnisse als die longitudinale Schnittführung