Observation of a new Xi(b) baryon

The first observation of a new b baryon via its strong decay into Xi(b)^- pi^+ (plus charge conjugates) is reported. The measurement uses a data sample of pp collisions at sqrt(s) = 7 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 5.3 inverse femtobarns. The known Xi(b)^- baryon is reconstructed via the decay chain Xi(b)^- to J/psi Xi^- to mu^+ mu^- Lambda^0 pi^-, with Lambda^0 to p pi^-. A peak is observed in the distribution of the difference between the mass of the Xi(b)^- pi^+ system and the sum of the masses of the Xi(b)^- and pi^+, with a significance exceeding five standard deviations. The mass difference of the peak is 14.84 +/- 0.74 (stat.) +/- 0.28 (syst.) MeV. The new state most likely corresponds to the J^P=3/2^+ companion of the Xi(b).Comment: Submitted to Physical Review Letter

Measurements of inclusive W and Z cross sections in pp collisions at root s=7 TeV

This is the pre-print version of the Published Article, which can be accessed from the link below - Copyright @ 2011 Springer VerlagMeasurements of inclusive W and Z boson production cross sections in pp collisions at sqrt(s)=7 TeV are presented, based on 2.9 inverse picobarns of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give sigma(pp to WX) times B(W to muon or electron + neutrino) = 9.95 \pm 0.07(stat.) \pm 0.28(syst.) \pm 1.09(lumi.) nb and sigma(pp to ZX) times B(Z to oppositely charged muon or electron pairs) = 0.931 \pm 0.026(stat.) \pm 0.023(syst.) \pm 0.102(lumi.) nb. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions, are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty of less than 4%, are also reported

Measurement of the charge ratio of atmospheric muons with the CMS detector

This is the pre-print version of this Article. The official published version can be accessed from the link below - Copyright @ 2010 ElsevierWe present a measurement of the ratio of positive to negative muon fluxes from cosmic ray interactions in the atmosphere, using data collected by the CMS detector both at ground level and in the underground experimental cavern at the CERN LHC. Muons were detected in the momentum range from 5 GeV/c to 1 TeV/c. The surface flux ratio is measured to be 1.2766 \pm 0.0032(stat.) \pm 0.0032 (syst.), independent of the muon momentum, below 100 GeV/c. This is the most precise measurement to date. At higher momenta the data are consistent with an increase of the charge ratio, in agreement with cosmic ray shower models and compatible with previous measurements by deep-underground experiments

Search for B → μ μ And B0 → μ+ μ- Decays

A search for the rare decays B → μ μ and B → μ μ is performed in pp collisions at ps = 7TeV, with a data sample corresponding to an integrated luminosity of 5 fb collected by the CMS experiment at the LHC. In both decays, the number of events observed after all selection requirements is consistent with the expectation from background plus standard model signal predictions. The resulting upper limits on the branching fractions are B(B → μ μ-) < 7:7 × 10 and B(B → μ μ ) < 1:8 × 10 at 95% confidence level

Measurement of dijet angular distributions and search for quark compositeness in pp collisions at √s=7TeV

Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at root s = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 pb(-1). The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda(+) = 5.6 TeV (Lambda(-) = 6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level

Realising Team-Working in the Field: An Agent-based Approach

Multi-agent systems technology is applied to enable co-operation between mobile workers in the field, minimising user intervention and increasing reachability. A component-based approach is taken to simplify the management of deployed co-operation services. A Personal Assistant running on a mobile device is introduced to show how an intelligent and autonomous agent can increase the utility of users during workforce co-operation processes. Finally, a real world trial of the technology by network installation and maintenance engineers in the UK is described. Some technical issues revealed during the trial are discussed, as is the impact of the technology on the business process

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Advertising and competition in theory practice and public policy

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This study analyses and compares the theories relating to advertising and competition in economics literature with their operation in the market-place, and with the attitudes and pronouncements of public policy towards advertising and competition. A survey of the main literature in economic theory concerned with advertising and competition includes the theory of value, the theory of the firm, and theories and empirical studies on the effects of advertising and imperfect competition on prices, profits, barriers to entry and product differentiation. Since no general agreement exists on these theories and research, the review is interspersed with criticisms which have been made about specific features of them, and also a short outline of alternative theories which are considered to give a more accurate account of the behaviour of firms in the real world. Consumer behaviour in the market is then studied from three viewpoints: a summary of the major academic theories of consumer behaviour; the results of some empirical research into consumer behaviour; and eight case histories of products and services which show how products are developed and introduced on the market. Finally, the economic theories are compared with the results of the empirical research and the case histories. The theory and practice of advertising and competition is then compared with extracts from the reports of public bodies to illustrate the attitude of public policy towards advertising and competition. The conclusions draw attention to the major discrepancies which appear to exist between theory and practice, and the implications that follow for public policy which seems to be predominantly based on the theory of the firm and the need to eliminate imperfections in the market such as product differentiation, advertising and non-price competition

Search in leptonic channels for heavy resonances decaying to long-lived neutral particles

Submitted to the Journal of High Energy Physics ; see paper for full list of authorsA search is performed for heavy resonances decaying to two long-lived massive neutral particles, each decaying to leptons. The experimental signature is a distinctive topology consisting of a pair of oppositely charged leptons originating at a separated secondary vertex. Events were collected by the CMS detector at the LHC during pp collisions at sqrt(s) = 7 TeV, and selected from data samples corresponding to 4.1 (5.1) inverse femtobarns of integrated luminosity in the electron (muon) channel. No significant excess is observed above standard model expectations, and an upper limit is set with 95% confidence level on the production cross section times the branching fraction to leptons, as a function of the long-lived massive neutral particle lifetime

Search for supersymmetry in events with a lepton, a photon, and large missing transverse energy in pp collisions at √s=7 TeV

A search is performed for an excess of events, over the standard model expectations, with a photon, a lepton, and large missing transverse energy in pp collisions root s = 7TeV. Such events are expected in many new physics models, in particular a theory that is broken via a gauge-mediated mechanism, when the lightest and neutral gauginos are mass degenerate. The data sample used in this search to an integrated luminosity of 35 pb(-1) collected with the CMS detector at the No evidence of such an excess above the standard model backgrounds, dominated by production, is found. The results are presented as 95% confidence level upper limits on the cross section for a benchmark gauge-mediated scenario, and are then converted into exclusion limits on the squark, gluino, and wino masses