197 research outputs found
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
Factors associated with self- and informant ratings of quality of life, well-being and life satisfaction in people with mild-to-moderate dementia: results from the Improving the experience of Dementia and Enhancing Active Life programme
Background
A large number of studies have explored factors related to self- and informant ratings of quality of life in people with dementia but many studies have had relatively small sample sizes and mainly focused on health conditions and dementia symptoms. The aim of this study is to compare self- and informant-rated quality of life, life satisfaction and wellbeing, and investigate the relationships of the two different rating methods with various social, psychological and health factors, using a large cohort study of community-dwelling people with dementia and carers in Great Britain.
Methods
This study included 1283 dyads of people with mild-to-moderate dementia and their primary carers in the Improving the experience of Dementia and Enhancing Active Life (IDEAL) study. Multivariate modelling was used to investigate associations of self- and informant-rated quality of life, life satisfaction and wellbeing with factors in five domains: psychological characteristics and health; social location; capitals, assets and resources; physical fitness and health; and managing everyday life with dementia.
Results
People with dementia rated their quality of life, life satisfaction and wellbeing more highly than did the informants. Despite these differences, the two approaches had similar relationships with social, psychological and physical health factors in the five domains.
Conclusions
Although self- and informant ratings differ, they display similar results when focusing on factors associated with quality of life, life satisfaction and wellbeing. Either self- or informant ratings may offer a reasonable source of information about people with dementia in terms of understanding associated factors
Psychology and aggression
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68264/2/10.1177_002200275900300301.pd
Production of pi+, pi-, K+, K-, p and p-bar in Light (uds), c and b Jets from Z0 Decays
We present improved measurements of the differential production rates of
stable charged particles in hadronic Z0 decays, and of charged pions, kaons and
protons identified over a wide momentum range using the SLD Cherenkov Ring
Imaging Detector. In addition to flavor-inclusive Z0 decays, measurements are
made for Z0 decays into light (u, d, s), c and b primary flavors, selected
using the upgraded Vertex Detector. Large differences between the flavors are
observed that are qualitatively consistent with expectations based upon
previously measured production and decay properties of heavy hadrons. These
results are used to test the predictions of QCD in the Modified Leading
Logarithm Approximation, with the ansatz of Local Parton-Hadron Duality, and
the predictions of three models of the hadronization process. The light-flavor
results provide improved tests of these predictions, as they do not include the
contribution of heavy-hadron production and decay; the heavy-flavor results
provide complementary model tests. In addition we have compared hadron and
antihadron production in light quark (as opposed to antiquark) jets.
Differences are observed at high momentum for all three charged hadron species,
providing direct probes of leading particle effects, and stringent constraints
on models.Comment: 44 pages, 14 figs; submitted to Phys. Rev.
Measurement of the ttbar Production Cross Section in ppbar collisions at sqrt s = 1.96 TeV in the All Hadronic Decay Mode
We report a measurement of the ttbar production cross section using the
CDF-II detector at the Fermilab Tevatron. The analysis is performed using 311
pb-1 of ppbar collisions at sqrt(s)=1.96 TeV. The data consist of events
selected with six or more hadronic jets with additional kinematic requirements.
At least one of these jets must be identified as a b-quark jet by the
reconstruction of a secondary vertex. The cross section is measured to be
sigma(tbart)=7.5+-2.1(stat.)+3.3-2.2(syst.)+0.5-0.4(lumi.) pb, which is
consistent with the standard model prediction.Comment: By CDF collaboratio
Search for long-lived doubly charged Higgs bosons in p(p)over-bar collisions at root s=1.96 TeV
We present a search for long-lived doubly charged Higgs bosons (H+/-+/-), with signatures of high ionization energy loss and muonlike penetration. We use 292 pb(-1) of data collected in p (p) over bar collisions at root s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. Observing no evidence of long-lived doubly charged particle production, we exclude H-L(+/-+/-) and H-R(+/-+/-) bosons with masses below 133 GeV/c(2) and 109 GeV/c(2), respectively. In the degenerate case we exclude H+/-+/- mass below 146 GeV/c(2). All limits are quoted at the 95% confidence level
Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV
Peer reviewe
Measurement of the W+W- Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Dilepton Events
We present a measurement of the W+W- production cross section using 184/pb of
ppbar collisions at a center-of-mass energy of 1.96 TeV collected with the
Collider Detector at Fermilab. Using the dilepton decay channel W+W- ->
l+l-vvbar, where the charged leptons can be either electrons or muons, we find
17 candidate events compared to an expected background of 5.0+2.2-0.8 events.
The resulting W+W- production cross section measurement of sigma(ppbar -> W+W-)
= 14.6 +5.8 -5.1 (stat) +1.8 -3.0 (syst) +-0.9 (lum) pb agrees well with the
Standard Model expectation.Comment: 8 pages, 2 figures, 2 tables. To be submitted to Physical Review
Letter
Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV
Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7ââfbâ1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale
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