Measurement of Resonance Parameters of Orbitally Excited Narrow B^0 Mesons

We report a measurement of resonance parameters of the orbitally excited (L=1) narrow B^0 mesons in decays to B^{(*)+}\pi^- using 1.7/fb of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the B^{*0}_2 state are measured to be m(B^{*0}_2) = 5740.2^{+1.7}_{-1.8}(stat.) ^{+0.9}_{-0.8}(syst.) MeV/c^2 and \Gamma(B^{*0}_2) = 22.7^{+3.8}_{-3.2}(stat.) ^{+3.2}_{-10.2}(syst.) MeV/c^2. The mass difference between the B^{*0}_2 and B^0_1 states is measured to be 14.9^{+2.2}_{-2.5}(stat.) ^{+1.2}_{-1.4}(syst.) MeV/c^2, resulting in a B^0_1 mass of 5725.3^{+1.6}_{-2.2}(stat.) ^{+1.4}_{-1.5}(syst.) MeV/c^2. This is currently the most precise measurement of the masses of these states and the first measurement of the B^{*0}_2 width.Comment: 7 pages, 1 figure, 1 table. Submitted to Phys.Rev.Let

Measurement of the fraction of t-tbar production via gluon-gluon fusion in p-pbar collisions at sqrt(s)=1.96 TeV

We present a measurement of the ratio of t-tbar production cross section via gluon-gluon fusion to the total t-tbar production cross section in p-pbar collisions at sqrt{s}=1.96 TeV at the Tevatron. Using a data sample with an integrated luminosity of 955/pb recorded by the CDF II detector at Fermilab, we select events based on the t-tbar decay to lepton+jets. Using an artificial neural network technique we discriminate between t-tbar events produced via q-qbar annihilation and gluon-gluon fusion, and find Cf=(gg->ttbar)/(pp->ttbar)<0.33 at the 68% confidence level. This result is combined with a previous measurement to obtain the most precise measurement of this quantity, Cf=0.07+0.15-0.07.Comment: submitted to Phys. Rev.

Decomposition of semigroup algebras

Let A \subseteq B be cancellative abelian semigroups, and let R be an integral domain. We show that the semigroup ring R[B] can be decomposed, as an R[A]-module, into a direct sum of R[A]-submodules of the quotient ring of R[A]. In the case of a finite extension of positive affine semigroup rings we obtain an algorithm computing the decomposition. When R[A] is a polynomial ring over a field we explain how to compute many ring-theoretic properties of R[B] in terms of this decomposition. In particular we obtain a fast algorithm to compute the Castelnuovo-Mumford regularity of homogeneous semigroup rings. As an application we confirm the Eisenbud-Goto conjecture in a range of new cases. Our algorithms are implemented in the Macaulay2 package MonomialAlgebras.Comment: 12 pages, 2 figures, minor revisions. Package may be downloaded at http://www.math.uni-sb.de/ag/schreyer/jb/Macaulay2/MonomialAlgebras/html

Leeway for the loyal: a model of employee discretion

This article examines the factors underlying task discretion from an economist's perspective. It argues that the key axis for understanding discretion is the trade-off between the positive effects of discretion on potential output per employee and the negative effects of greater leeway on work effort. In empirical analysis using matched employer-employee data, it is shown that discretion is strongly affected by the level of employee commitment. In addition, discretion is generally greater in high-skilled jobs, although not without exceptions, and lower where employees are under-skilled. Homeworking and flexitime policies raise employee discretion. The impact of teamworking is mixed. In about half of cases team members do not jointly decide about work matters, and the net effect of teams on task discretion in these cases is negative. In other cases, where team members do decide matters jointly, the impact is found to be neutral according to employees' perceptions, or positive according to managers' perceptions. There are also significant and substantial unobserved establishment-level factors which affect task discretion

Exploring the use of new school buildings through post-occupancy evaluation and participatory action research

This paper presents the results of the development and testing of an integrated post-occupancy evaluation (POE) approach for teachers, staff, pupils and community members using newly constructed school buildings. It focusses on three cases of UK secondary schools, demonstrating how users can be inspired to engage with the problems of school design and energy use awareness. The cases provided new insights into the engagement of school teachers, staff and young people regarding issues of sustainability, management, functional performance and comfort. The integrative approach adopted in these cases provided a more holistic understanding of these buildings’ performance than could have been achieved by either observational or more traditional questionnaire-based methods. Moreover, the whole-school approach, involving children in POE, provided researchers with highly contextualised information about how a school is used, how to improve the quality of school experiences (both socially and educationally) and how the school community is contributing to the building's energy performance. These POE methods also provided unique opportunities for children to examine the social and cultural factors impeding the adoption of energy-conscious and sustainable behaviours

Search for a Higgs Boson Decaying to Two W Bosons at CDF

We present a search for a Higgs boson decaying to two W bosons in ppbar collisions at sqrt(s)=1.96 TeV center-of-mass energy. The data sample corresponds to an integrated luminosity of 3.0 fb-1 collected with the CDF II detector. We find no evidence for production of a Higgs boson with mass between 110 and 200 GeV/c^2, and determine upper limits on the production cross section. For the mass of 160 GeV/c^2, where the analysis is most sensitive, the observed (expected) limit is 0.7 pb (0.9 pb) at 95% Bayesian credibility level which is 1.7 (2.2) times the standard model cross section

Top Quark Mass Measurement in the Lepton plus Jets Channel Using a Modified Matrix Element Method

46 pages, 16 figures. Edited in response to referee comments and resubmitted to Phys. Rev. DWe report a measurement of the top quark mass, m_t, obtained from ppbar collisions at sqrt(s) = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. We analyze a sample corresponding to an integrated luminosity of 1.9 fb^-1. We select events with an electron or muon, large missing transverse energy, and exactly four high-energy jets in the central region of the detector, at least one of which is tagged as coming from a b quark. We calculate a signal likelihood using a matrix element integration method, with effective propagators to take into account assumptions on event kinematics. Our event likelihood is a function of m_t and a parameter JES that determines /in situ/ the calibration of the jet energies. We use a neural network discriminant to distinguish signal from background events. We also apply a cut on the peak value of each event likelihood curve to reduce the contribution of background and badly reconstructed events. Using the 318 events that pass all selection criteria, we find m_t = 172.7 +/- 1.8 (stat. + JES) +/- 1.2 (syst.) GeV/c^2.We report a measurement of the top quark mass, mt, obtained from pp̅ collisions at √s=1.96  TeV at the Fermilab Tevatron using the CDF II detector. We analyze a sample corresponding to an integrated luminosity of 1.9  fb-1. We select events with an electron or muon, large missing transverse energy, and exactly four high-energy jets in the central region of the detector, at least one of which is tagged as coming from a b quark. We calculate a signal likelihood using a matrix element integration method, where the matrix element is modified by using effective propagators to take into account assumptions on event kinematics. Our event likelihood is a function of mt and a parameter JES (jet energy scale) that determines in situ the calibration of the jet energies. We use a neural network discriminant to distinguish signal from background events. We also apply a cut on the peak value of each event likelihood curve to reduce the contribution of background and badly reconstructed events. Using the 318 events that pass all selection criteria, we find mt=172.7±1.8(stat+JES)±1.2(syst)  GeV/c2.Peer reviewe

Search for Long-Lived Massive Charged Particles in 1.96 TeV \bar{p}p} Collisions

16 pages, 2 figures; Revision to fix PDF errors on some displays/printersWe performed a signature-based search for long-lived charged massive particles (CHAMPs) produced in 1.0 $\rm{fb}^{-1}$ of $\bar{p}p$ collisions at $\sqrt{s}=1.96$ TeV, collected with the CDF II detector using a high transverse-momentum ($p_T$) muon trigger. The search used time-of-flight to isolate slowly moving, high-$p_T$ particles. One event passed our selection cuts with an expected background of $1.9 \pm 0.2$ events. We set an upper bound on the production cross section, and, interpreting this result within the context of a stable scalar top quark model, set a lower limit on the particle mass of 249 GeV/$c^2$ at 95% C.L.We performed a signature-based search for long-lived charged massive particles produced in 1.0  fb-1 of pp̅ collisions at √s=1.96  TeV, collected with the CDF II detector using a high transverse-momentum (pT) muon trigger. The search used time of flight to isolate slowly moving, high-pT particles. One event passed our selection cuts with an expected background of 1.9±0.2 events. We set an upper bound on the production cross section and, interpreting this result within the context of a stable scalar top-quark model, set a lower limit on the particle mass of 249  GeV/c2 at 95% C.L.Peer reviewe

Search for WW and WZ production in lepton plus jets final state at CDF

submitted to Phys. Rev. D (RC)We present a search for WW and WZ production in final states that contain a charged lepton (electron or muon) and at least two jets, produced in sqrt(s) = 1.96 TeV ppbar collisions at the Fermilab Tevatron, using data corresponding to 1.2 fb-1 of integrated luminosity collected with the CDF II detector. Diboson production in this decay channel has yet to be observed at hadron colliders due to the large single W plus jets background. An artificial neural network has been developed to increase signal sensitivity, as compared with an event selection based on conventional cuts. We set a 95% confidence level upper limit of sigma_{WW}* BR(W->lnu,W->jets)+ sigma_{WZ}*BR(W->lnu,Z->jets)We present a search for WW and WZ production in final states that contain a charged lepton (electron or muon) and at least two jets, produced in √s=1.96  TeV pp̅ collisions at the Fermilab Tevatron, using data corresponding to 1.2  fb-1 of integrated luminosity collected with the CDF II detector. Diboson production in this decay channel has yet to be observed at hadron colliders due to the large single W plus jets background. An artificial neural network has been developed to increase signal sensitivity, as compared with an event selection based on conventional cuts. We set a 95% confidence level upper limit of σWW×BR(W→ℓνℓ,W→jets)+σWZ×BR(W→ℓνℓ,Z→jets)<2.88  pb, which is consistent with the standard model next-to-leading-order cross section calculation for this decay channel of 2.09±0.12  pb.Peer reviewe

A search for high-mass resonances decaying to dimuons at CDF

We present a search for high-mass neutral resonances using dimuon data corresponding to an integrated luminosity of 2.3 fb$^{-1}$ collected in {$p\bar p$} collisions at {$\sqrt{s}$ = 1.96 TeV} by the CDF II detector at the Fermilab Tevatron. No significant excess above the standard model expectation is observed in the dimuon invariant-mass spectrum. We set 95% confidence level upper limits on $\sigma \cdot BR (p \bar{p} \to X \to \mu \bar{\mu})$, where $X$ is a boson with spin 0, 1, or 2. Using these cross section limits, we determine lower mass limits on sneutrinos in R-parity-violating supersymmetric models, $Z'$ bosons, and Kaluza-Klein gravitons in the Randall-Sundrum model.We present a search for high-mass neutral resonances using dimuon data corresponding to an integrated luminosity of 2.3  fb-1 collected in pp̅ collisions at √s=1.96  TeV by the CDF II detector at the Fermilab Tevatron. No significant excess above the standard model expectation is observed in the dimuon invariant-mass spectrum. We set 95% confidence level upper limits on σBR(pp̅ →X→μμ̅ ), where X is a boson with spin-0, 1, or 2. Using these cross section limits, we determine lower mass limits on sneutrinos in R-parity-violating supersymmetric models, Z′ bosons, and Kaluza-Klein gravitons in the Randall-Sundrum model.Peer reviewe