Data Quality Monitoring for the CMS Electromagnetic Calorimeter

One of the CMS design objectives is to construct and operate a very high quality electromagnetic calorimeter. The detector performance will be monitored using applications based on the CMS Data Quality Monitoring (DQM) framework and running on the High-Level Trigger Farm as well as on local DAQ systems. The monitorable quantities are organized into hierarchical structures based on the physics content. The information produced is delivered to client applications according to their subscription requests. The client applications process the received quantities, according to pre-defined analyses, making the results immediately available, and store the results in a database, and in the form of static web pages, for subsequent studies. We describe here the functionalities of the CMS ECAL DQM applications and report about their use in a real environment

Inclusive Measurements of Vub from BaBar

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The Data Quality Monitoring for the CMS Electromagnetic Calorimeter

The detector performance of the CMS electromagnetic calorimeter is monitored using applications based on the CMS Data Quality Monitoring (DQM) framework and running on the High-Level Trigger Farm as well as on local DAQ systems. The monitorable quantities are organized into hierarchical structures based on the physics content. The information produced is accessible by client applications according to their subscription requests. The client applications process the received quantities, according to pre-defined analyses, making the results immediately available, while also storing the results in a database, and in the form of static web pages, for subsequent studies. We describe here the functionalities of the CMS ECAL DQM applications and report about their use in real environments

Functions and Requirements of the CMS Centre at CERN

This report of the CMS Centre Requirements and Technical Assessment Group describes the functions of the CMS Centre on the CERN Meyrin site in terms of data quality monitoring, calibrations and rapid analysis and operations of the offline computing systems. It then defines the corresponding requirements for building space, computing consoles and other equipment, technical services and refurbishments, and communications systems

Search for supersymmetry in electroweak production with photons and large missing transverse energy in pp collisions at sqrt(s) = 8 TeV

Results are reported from a search for supersymmetry with gauge-mediated supersymmetry breaking in electroweak production. Final states with photons and large missing transverse energy ( View the MathML sourceETmiss) were examined. The data sample was collected in pp collisions at View the MathML sources=8TeV with the CMS detector at the LHC and corresponds to 7.4View the MathML sourcefb−1. The analysis focuses on scenarios in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape undetected. The data were obtained using a specially designed trigger with dedicated low thresholds, providing good sensitivity to signatures with photons, View the MathML sourceETmiss, and low hadronic energy. No excess of events over the standard model expectation is observed. The results are interpreted using the model of general gauge mediation. With the wino mass fixed at 10View the MathML sourceGeV above that of the bino, wino masses below 710View the MathML sourceGeV are excluded at 95% confidence level. Constraints are also set in the context of two simplified models, for which the analysis sets the lowest cross section limits on the electroweak production of supersymmetric particles

Measurement of transverse momentum relative to dijet systems in PbPb and pp collisions at sqrt(s_NN) = 2.76 TeV

An analysis of dijet events in PbPb and pp collisions is performed to explore the properties of energy loss by partons traveling in a quark-gluon plasma. Data are collected at a nucleon-nucleon center-of-mass energy of 2.76 TeV at the LHC. The distribution of transverse momentum (p T) surrounding dijet systems is measured by selecting charged particles in different ranges of p T and at different angular cones of pseudorapidity and azimuth. The measurement is performed as a function of centrality of the PbPb collisions, the p T asymmetry of the jets in the dijet pair, and the distance parameter R used in the anti-k T jet clustering algorithm. In events with unbalanced dijets, PbPb collisions show an enhanced multiplicity in the hemisphere of the subleading jet, with the p T imbalance compensated by an excess of low-p T particles at large angles from the jet axes

Measurements of t t-bar spin correlations and top quark polarization using dilepton final states in pp collisions at sqrt(s) = 8 TeV

Measurements of the top quark-antiquark (tt¯) spin correlations and the top quark polarization are presented for tt¯ pairs produced in pp collisions at s√=8  TeV. The data correspond to an integrated luminosity of 19.5  fb−1 collected with the CMS detector at the LHC. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The spin correlations and polarization are measured from the angular distributions of the two selected leptons, both inclusively and differentially, with respect to the invariant mass, rapidity, and transverse momentum of the tt¯ system. The measurements are unfolded to the parton level and found to be in agreement with predictions of the standard model. A search for new physics in the form of anomalous top quark chromo moments is performed. No evidence of new physics is observed, and exclusion limits on the real part of the chromo-magnetic dipole moment and the imaginary part of the chromo-electric dipole moment are evaluated

Differential cross section measurements for the production of a W boson in association with jets in proton-proton collisions at sqrt(s) = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pTpT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HTHT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb−1. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pTpT distributions of the leading jets at high pTpT values, the distributions of the HTHT at high-HTHT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values

Search for pair production of excited top quarks in the lepton+jets final state

A search is performed for pair-produced spin-3/2 excited top quarks (t∗t ̄∗), each decaying to a top quark and a gluon. The search uses data collected with the CMS detector from pp collisions at a center-of-mass energy of s√ = 8 TeV, selecting events that have a single isolated muon or electron, an imbalance in transverse momentum, and at least six jets, of which one must be compatible with originating from the fragmentation of a b quark. The data, corresponding to an integrated luminosity of 19.5 fb−1, show no significant excess over standard model predictions, and provide a lower limit of 803 GeV at 95% confidence on the mass of the spin-3/2 t* quark in an extension of the Randall-Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. This is the first search for a spin-3/2 excited top quark performed at the LHC

Search for new physics in the multijet and missing transverse momentum final state in proton-proton collisions at sqrt(s) = 8 TeV

A search for new physics is performed in multijet events with large missing transverse momentum produced in proton-proton collisions at s√ = 8 TeV using a data sample corresponding to an integrated luminosity of 19.5 fb−1 collected with the CMS detector at the LHC. The data sample is divided into three jet multiplicity categories (3-5, 6-7, and ≥8 jets), and studied further in bins of two variables: the scalar sum of jet transverse momenta and the missing transverse momentum. The observed numbers of events in various categories are consistent with backgrounds expected from standard model processes. Exclusion limits are presented for several simplified supersymmetric models of squark or gluino pair production