1,021 research outputs found
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.
Surviving rather than thriving: Understanding the experiences of women coaches using a theory of gendered social well-being
In shifting our gaze to the sociological impact of being in the minority, the purpose of this study was to substantiate a model of gendered social well-being to appraise women coaches’ circumstances, experiences and challenges as embedded within the social structures and relations of their profession. This is drawn on indepth interviews with a sample of head women coaches within the UK. The findings demonstrate that personal lives, relationships, social and family commitments were sidelined by many of the participants in order to meet the expectations of being a (woman) coach. We locate these experiences in the organisational practices of high performance sport which hinder women coaches from having meaningful control over their lives. The complexities of identity are also revealed through the interplay of gender with (dis)ability, age and whiteness as evidence of hegemonic femininity within the coaching profession. Consequently, for many women, coaching is experienced as a ‘developmental dead-end’
Trial protocol OPPTIMUM : does progesterone prophylaxis for the prevention of preterm labour improve outcome?
Background
Preterm birth is a global problem, with a prevalence of 8 to 12% depending on location. Several large trials and systematic reviews have shown progestogens to be effective in preventing or delaying preterm birth in selected high risk women with a singleton pregnancy (including those with a short cervix or previous preterm birth). Although an improvement in short term neonatal outcomes has been shown in some trials these have not consistently been confirmed in meta-analyses. Additionally data on longer term outcomes is limited to a single trial where no difference in outcomes was demonstrated at four years of age of the child, despite those in the “progesterone” group having a lower incidence of preterm birth.
Methods/Design
The OPPTIMUM study is a double blind randomized placebo controlled trial to determine whether progesterone prophylaxis to prevent preterm birth has long term neonatal or infant benefit. Specifically it will study whether, in women with singleton pregnancy and at high risk of preterm labour, prophylactic vaginal natural progesterone, 200 mg daily from 22 – 34 weeks gestation, compared to placebo, improves obstetric outcome by lengthening pregnancy thus reducing the incidence of preterm delivery (before 34 weeks), improves neonatal outcome by reducing a composite of death and major morbidity, and leads to improved childhood cognitive and neurosensory outcomes at two years of age. Recruitment began in 2009 and is scheduled to close in Spring 2013. As of May 2012, over 800 women had been randomized in 60 sites.
Discussion
OPPTIMUM will provide further evidence on the effectiveness of vaginal progesterone for prevention of preterm birth and improvement of neonatal outcomes in selected groups of women with singleton pregnancy at high risk of preterm birth. Additionally it will determine whether any reduction in the incidence of preterm birth is accompanied by improved childhood outcome
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 of collisions at TeV, collected with the CDF II detector using a high transverse-momentum () muon trigger. The search used time-of-flight to isolate slowly moving, high- particles. One event passed our selection cuts with an expected background of 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/ 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
Obstetric and Perinatal Outcomes in Type 1 Diabetic Pregnancies: A large, population-based study
The aim of this epidemiological study was to elucidate whether in recent years, obstetric and
perinatal outcomes in pregnancies complicated by type 1 diabetes (T1DM) have improved or
not. The objective was also to identify possible risk factors for adverse outcome for the
mother, fetus and the newborn. All studies (Ι-ΙV) included in this thesis were based on
national data from the Swedish Medical Birth Registry, during the time period 1991-2007.
In 5,089 type 1 diabetic pregnancies and 1.2 million controls we found significantly increased
risks of all adverse outcomes in women with T1DM: adjusted odds ratios: severe
preeclampsia: 4.47 (3.77-5.31), Caesarean delivery: 5.31 (4.97-5.69), stillbirth: 3.34 (2.46-
4.55), perinatal mortality: 3.29 (2.50-4.33), major malformations: 2.50 (2.13-2.94) and large
for gestational age: LGA (birth weight ≥ +2 SD): 11.45 (10.61-12.36) (study Ι).
The markedly elevated odds of an LGA outcome inspired us to characterize in more detail the
distribution of birth size in a large national cohort of T1DM offspring (study ΙΙ n=3,705) and
to investigate if disproportionate body composition was associated with increased risk of
perinatal complications (study ΙΙΙ n=3,517). Percentiles for birth weight (BW), birth length
(BL) and head circumference (HC) were formed based on data from non-diabetic pregnancies
and standard deviation scores (SDS) were calculated for BW, BL and HC. The ponderal
index (PI: BW in grams/(BL in cm) ³ was used as a proxy for body proportionality and fat
mass and we defined disproportionate/overweight LGA as infants with a BW and PI ≥90th
percentile for gestational age and gender.
The distributions of BW, BL and HC were all unimodal but significantly shifted to the right of
the normal reference. The distribution for BW was most markedly shifted to the right. 47%
were LGA with a BW ≥90th adjusted percentile. The mean ponderal index (PI) was
significantly increased and 46% of LGA infants were disproportionate with a PI ≥90th
percentile and thus overweight at birth. A novel and unexpected finding was that fetal
macrosomia was more pronounced in preterm and female infants (study ΙΙ). Surprisingly,
neonatal outcome was independent of body proportionality in appropriate for gestational age
(AGA) and LGA infants. The risk of adverse outcome was significantly increased in LGA
compared with AGA infants born at term (study ΙΙΙ). There was a significant interaction
between gestational age and body weight with prematurity overriding LGA as a risk factor for
neonatal morbidity in moderately preterm infants.
In study ΙV, we examined the risk of adverse outcome in relation to pre-pregnancy body mass
index in a national cohort of 3,457 T1DM pregnancies compared to 764,498 non-diabetic
pregnancies. Maternal overweight/obesity increases the risk of adverse outcome in both
women with and without T1DM. Within the T1DM cohort, obesity was associated with
increased odds of major malformations adjusted OR: 1.77 (1.18-2.65) and preeclampsia
adjusted OR: 1.74 (1.35-2.25). T1DM was a significant effect modifier of the association
between BMI and major malformations, preeclampsia, LGA and neonatal overweight.
Conclusion: In spite of major improvements in the management of type 1 diabetic pregnancies
over the years, the present findings clearly demonstrate that T1DM pregnancies still are
associated with significantly increased risk of adverse outcomes. An important observation is
the rising incidence of LGA infants, which partly can be attributed to a concomitant increase
in maternal BMI. This development is worrying as LGA infants face an excess risk of both
perinatal and future complications as compared to normal sized infants. The novel and
unexpected finding of a gender difference in fetal macrosomia requires further investigations
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 collected in {} collisions at { = 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 , where 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, 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
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