Search for the standard model Higgs boson in tau final states

We present a search for the standard model Higgs boson using hadronically decaying tau leptons, in 1 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron pp collider. We select two final states: tau+/- plus missing transverse energy and b jets, and tau+ tau- plus jets. These final states are sensitive to a combination of associated W/Z boson plus Higgs boson, vector boson fusion, and gluon-gluon fusion production processes. The observed ratio of the combined limit on the Higgs production cross section at the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of 115 GeV.

Search for resonant diphoton production with the D0 detector

We present a search for a narrow resonance in the inclusive diphoton final state using approximately 2.7 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron pp Collider. We observe good agreement between the data and the background prediction, and set the first 95% C.L. upper limits on the production cross section times the branching ratio for decay into a pair of photons for resonance masses between 100 and 150 GeV. This search is also interpreted in the context of several models of electroweak symmetry breaking with a Higgs boson decaying into two photons.

Cross-sectional analysis of testosterone therapies in hypopituitary men on stable pituitary hormone replacement

OBJECTIVE

The last decade has seen a proliferation in options for testosterone replacement. However, little is known as to the benefits of different treatment modalities. Our objective was to determine the testosterone prescription pattern and to examine the impact on various outcome measures.

SUBJECTS AND METHODS

A total of 816 adult-onset hypopituitary males on stable pituitary replacement for at least 1 year were identified from the KIMS database. Patients were classified as either eugonadal (n = 106), or hypogonadal (n = 710) on intramuscular (IM, n = 558), oral (n = 74), transdermal (n = 61), and depot (n = 17) testosterone.

RESULTS

After 1 year of stable pituitary replacement therapy, body composition, cardiovascular parameters, GH replacement and quality of life were not significantly different in androgen-replaced hypogonadal patients compared to eugonadal patients. There were no differences in outcome variables within the hypogonadal group according to the testosterone replacement regimen used and no difference in response to GH therapy.

CONCLUSIONS

The majority of hypopituitary patients in the last decade have received IM testosterone. Body composition, cardiovascular parameters, GH replacement and quality of life were not different between eugonadal and hypogonadal patients and were not differentially affected by the mode of testosterone replacement. These findings are reassuring that there is no major difference in response to different testosterone replacement regimens.

Measurement of the Zgamma --> nunu[over ]gamma production cross section and limits on anomalous ZZgamma and Zgammagamma couplings in pp[over] collisions at sqrt[s] = 1.96 TeV

We present the first observation of the Zgamma --> nunu[over ]gamma process at the Fermilab Tevatron at 5.1 standard deviations significance, based on 3.6 fb;{-1} of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp[over ] Collider at sqrt[s] = 1.96 TeV. The measured Zgamma production cross section multiplied by the branching fraction of Z --> nunu[over] is 32 +/- 9(stat + syst) +/-2 (lumi) fb for the photon E_{T} > 90 GeV. It is in agreement with the standard model prediction of 39 +/- 4 fb. We set limits on anomalous trilinear Zgammagamma and ZZgamma gauge boson couplings, most of which are the most restrictive to date.

Search for charged higgs bosons decaying into top and bottom quarks in pp[over ] collisions

We describe a search for production of a charged Higgs boson, qq[over ];{'}-->H;{+}, reconstructed in the tb[over ] final state in the mass range 180< or =M_{H;{+}}< or =300 GeV. The search was undertaken at the Fermilab Tevatron collider with a center-of-mass energy sqrt[s]=1.96 TeV and uses 0.9 fb;{-1} of data collected with the D0 detector. We find no evidence for charged Higgs boson production and set upper limits on the production cross section in the types I, II, and III two-Higgs-doublet models (2HDMs). An excluded region in the (M_{H;{+}}, tanbeta) plane for type I 2HDM is presented.

Measurement of gamma+b+X and gamma+c+X Production Cross Sections in pp[over ] Collisions at sqrt[s]=1.96 TeV

First measurements of the differential cross sections d;{3}sigma/(dp_{T};{gamma}dy;{gamma}dy;{jet}) for the inclusive production of a photon in association with a heavy quark (b, c) jet are presented, covering photon transverse momenta 30<p_{T};{gamma}<150 GeV, photon rapidities |y;{gamma}|<1.0, jet rapidities |y;{jet}|<0.8, and jet transverse momenta p_{T};{jet}>15 GeV. The results are based on an integrated luminosity of 1 fb;{-1} in pp[over ] collisions at sqrt[s]=1.96 TeV recorded with the D0 detector at the Fermilab Tevatron Collider. The results are compared with next-to-leading order perturbative QCD predictions.

Search for long-lived charged massive particles with the D0 detector

We search for long-lived charged massive particles using 1.1 fb;{-1} of data collected by the D0 detector at the Fermilab Tevatron pp[over ] Collider. Time-of-flight information is used to search for pair produced long-lived tau sleptons, gauginolike charginos, and Higgsino-like charginos. We find no evidence of a signal and set 95% C.L. cross section upper limits for staus, which vary from 0.31 to 0.04 pb for stau masses between 60 and 300 GeV. We also set lower mass limits of 206 GeV (171 GeV) for pair produced charged gauginos (Higgsinos).

Evidence of WW and WZ production with lepton + jets final states in pp collisions at square root s=1.96 TeV

We present first evidence for WW+WZ production in lepton + jets final states at a hadron collider. The data correspond to 1.07 fb-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron in pp collisions at square root s=1.96 TeV. The observed cross section for WW+WZ production is 20.2+/-4.5 pb, consistent with the standard model and more precise than previous measurements in fully leptonic final states. The probability that background fluctuations alone produce this excess is <5.4 x 10-6, which corresponds to a significance of 4.4 standard deviations.

Search for anomalous top-quark couplings with the D0 detector

Anomalous Wtb couplings modify the angular correlations of the top-quark decay products and change the single top-quark production cross section. We present limits on anomalous top-quark couplings by combining information from W boson helicity measurements in top-quark decays and anomalous coupling searches in the single top-quark final state. We set limits on right-handed vector couplings as well as left-handed and right-handed tensor couplings based on about 1 fb(-1) of data collected by the D0 experiment.

Measurement of the lifetime of the Bc+/- meson in the semileptonic decay channel

Using approximately 1.3 fb(-1) of data collected by the D0 detector between 2002 and 2006, we measure the lifetime of the Bc+/- meson in the Bc-/+-->J/psimicro+/-+X final state. A simultaneous unbinned likelihood fit to the J/psi+micro invariant mass and lifetime distributions yields a signal of 881+/-80(stat) candidates and a lifetime measurement of tau(Bc+/-)=0.448(-0.036)(+0.038)(stat)+/-0.032(syst) ps.

Evidence for the decay Bs0-->Ds(*)Ds(*) and a measurement of DeltaGammasCP/Gammas

We search for the semi-inclusive process Bs0-->Ds(*)Ds(*) using 2.8 fb(-1) of pp collisions at sqrt[s]=1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We observe 26.6+/-8.4 signal events with a significance above background of 3.2 standard deviations yielding a branching ratio of B(Bs0-->Ds(*)Ds(*))=0.035+/-0.010(stat.)+/-0.011(syst.). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the Bs0 decays resulting in a width difference of DeltaGammasCP/Gammas=0.072+/-0.021(stat.)+/-0.022(syst.).

Search for neutral Higgs Bosons at high tanbeta in the b(h/H/A)-->btau;{+}tau;{-} channel

The first search in pp[over ] collisions at sqrt[s]=1.96 TeV for the production of neutral Higgs bosons in association with bottom quarks and decaying in two tau leptons is presented. The cross section for this process is enhanced in many extensions of the standard model, such as its minimal supersymmetric extension (MSSM) at large tanbeta. The data, corresponding to an integrated luminosity of 328 pb;{-1}, were collected with the D0 detector at the Fermilab Tevatron Collider. An upper limit is set on the production cross section of neutral Higgs bosons in the mass range of 90 to 150 GeV, and this limit is used to exclude part of the MSSM parameter space.

Search for associated W and Higgs Boson production in pp[over ] collisions at sqrt[s]=1.96 TeV

We present results of a search for WH-->lnubb[over ] production in pp[over ] collisions based on the analysis of 1.05 fb;{-1} of data collected by the D0 experiment at the Fermilab Tevatron, using a neural network for separating the signal from backgrounds. No signal-like excess is observed, and we set 95% C.L. upper limits on the WH production cross section multiplied by the branching ratio for H-->bb[over ] for Higgs boson masses between 100 and 150 GeV. For a mass of 115 GeV, we obtain an observed (expected) limit of 1.5 (1.4) pb, a factor of 11.4 (10.7) times larger than the standard model prediction.

Measurement of the semileptonic branching ratio of B_{s};{0} to an orbitally excited D_{s};{**} state: Br(B_{s};{0}-->D_{s1};{-}(2536)mu;{+}nuX)

In a data sample of approximately 1.3 fb;{-1} collected with the D0 detector between 2002 and 2006, the orbitally excited charm state D_{s1};{+/-}(2536) has been observed with a measured mass of 2535.7+/-0.6(stat)+/-0.5(syst) MeV/c;{2} via the decay mode B_{s};{0}-->D_{s1};{-}(2536)mu;{+}nu_{mu}X. A first measurement is made of the branching ratio product Br(b[over ]-->D_{s1};{-}(2536)mu;{+}nu_{mu}X)xBr(D_{s1};{-}-->D;{*-}K_{S};{0}). Assuming that D_{s1};{-}(2536) production in semileptonic decay is entirely from B_{s};{0}, an extraction of the semileptonic branching ratio Br(B_{s};{0}-->D_{s1};{-}(2536)mu;{+}nu_{mu}X) is made.

Search for large extra spatial dimensions in the dielectron and diphoton channels in pp[over ] collisions at sqrt[s]=1.96 TeV

We report on a search for large extra spatial dimensions in the dielectron and diphoton channels using a data sample of 1.05 fb;{-1} of pp[over ] collisions at a center-of-mass energy of 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. The invariant mass spectrum of the data agrees well with the prediction of the standard model. We find the most restrictive 95% C.L. lower limits on the effective Planck scale between 2.1 and 1.3 TeV for 2 to 7 extra dimensions.

Measurement of the angular and lifetime parameters of the decays Bd0-->J/psiK*0 and Bs0-->J/psiphi

We present measurements of the linear polarization amplitudes and the strong relative phases that describe the flavor-untagged decays Bd0-->J/psiK*0 and Bs0-->J/psiphi in the transversity basis. We also measure the mean lifetime taus of the Bs0 mass eigenstates and the lifetime ratio taus/taud. The analyses are based on approximately 2.8 fb(-1) of data recorded with the D0 detector. From our measurements of the angular parameters we conclude that there is no evidence for a deviation from flavor SU(3) symmetry for these decays and that the factorization assumption is not valid for the Bd0-->J/psiK*0 decay.

Search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology at sqrt[s]=1.96 TeV

We report a search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology, using an integrated luminosity of 0.93 fb;{-1} recorded by the D0 detector at the Fermilab Tevatron pp[over ] Collider. The analysis includes signal contributions from pp[over ]-->ZH-->nunu[over ]bb[over ], as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the absence of a signal, we set limits on sigma(pp[over ]-->VH)xB(H-->bb[over ]) at the 95% C.L. of 2.6-2.3 pb, for Higgs boson masses in the range 105-135 GeV, where V=W, Z. The corresponding expected limits range from 2.8 to 2.0 pb.

Search for third generation scalar leptoquarks decaying into taub

We have searched for third generation leptoquarks (LQ3) using 1.05 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider operating at sqrt[s]=1.96 TeV. We set a 95% C.L. lower limit of 210 GeV on the mass of a scalar LQ3 state decaying solely to a b quark and a tau lepton.

Measurement of Bs0 mixing parameters from the flavor-tagged decay Bs0-->J/psiphi

From an analysis of the flavor-tagged decay Bs0-->J/psiphi we obtain the width difference between the Bs0 light and heavy mass eigenstates, DeltaGammas = 0.19+/-0.07(stat)(-0.01)+0.02(syst) ps(-1), and the CP-violating phase, phi s= -0.57(-0.30)+0.24(stat)(-0.02)+0.08(syst). The allowed 90% CL intervals of DeltaGammas and phi s are 0.06 < DeltaGammas < 0.30 ps(-1) and -1.20 < phi s < 0.06, respectively. The data sample corresponds to an integrated luminosity of 2.8 fb(-1) accumulated with the D0 detector at the Fermilab Tevatron collider.

Observation of the doubly strange b baryon Omegab-

We report the observation of the doubly strange b baryon Omegab- in the decay channel Omegab(-)-->J/psiOmega-, with J/psi-->mu+mu(-) and Omega(-)-->LambdaK(-)-->(ppi-)K-, in pp collisions at sqrt[s]=1.96 TeV. Using approximately 1.3 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17.8+/-4.9(stat)+/-0.8(syst) Omegab- signal events at a mass of 6.165+/-0.010(stat)+/-0.013(syst) GeV. The significance of the observed signal is 5.4sigma, corresponding to a probability of 6.7 x 10(-8) of it arising from a background fluctuation.

Inverse association of high-fat diet preference and anxiety-like behavior: a putative role for urocortin 2

The aim of this study was to investigate whether the preference for a palatable high-fat diet (HFD) is associated with response to novelty and with anxiety-like behavior in rats and whether such fat preference correlates with gene expression of hypothalamic neuropeptides related to feeding. We subjected male rats to two tests of exploration of novel environments: the multivariate concentric square field (MCSF) and the elevated plus maze (EPM). The rats were then exposed to a 5-day test of preference for a palatable HFD versus reference diets. Messenger RNA (mRNA) levels of 21 neuropeptides were investigated by quantitative polymerase chain reaction. We found a strong positive correlation of HFD preference and open-arm activity in the EPM (% open-arm time, r(s) = 0.629, df = 26, P < 0.001). Thus, HFD preference was inversely associated with anxiety-like behavior. The same association was found for HFD preference and behavior in the MCSF (bridge entries, r(s) = 0.399, df = 23, P = 0.048). In addition, the HFD preference was positively correlated (r(s) = 0.433, df = 25, P = 0.021) with hypothalamic mRNA levels of urocortin 2 (Ucn 2). Moreover, behavior in the EPM was significantly correlated with expression levels of the receptor for Ucn 2, the corticotropin-releasing factor receptor 2, in the hypothalamus (r(s) = 0.382, df = 33, P = 0.022, pituitary (r(s) = 0.494, df = 31, P = 0.004) and amygdala (r(s) = 0.381, df = 30, P = 0.032). We conclude that preference for palatable HFD is inversely associated with anxiety and propose that Ucn 2 signaling may play a role in this association.

Influence of disease features on adherence to prophylactic migraine medication

OBJECTIVES

Randomized controlled trials of prophylactic treatments for migraine focus on the effects in an ideal situation and underestimate the impact of non-adherence, which in this study was examined in a natural setting.

MATERIALS AND METHODS

A sample of 174 adult migraineurs with a current prescription of pharmacological prophylaxis were consecutively recruited at a specialist clinic. Logistic regression analysis was performed to analyse the association between adherence (self-reported with the Medication Adherence Report Scale) and number of years with migraine, frequency of attacks, number of days with migraine per month, attack duration, presence of cardinal features, mean intensity of pain, and recovery between attacks.

RESULTS

One third (35%) were non-adherent. Neither demographic characteristics nor any of the disease specific variables were significantly associated with adherence.

CONCLUSION

Characteristics of the disease per se did not predict non-adherence which was also observed among patients with severe migraine. The full benefit of drugs cannot be realized at currently achieved levels of adherence.

Search for anomalous Wtb couplings in single top quark production

In 0.9 fb(-1) of pp[over] collisions, the D0 Collaboration presented evidence for single top quark production in events with an isolated lepton, missing transverse momentum, and two to four jets. We examine these data to study the Lorentz structure of the Wtb coupling. The standard model predicts a left-handed vector coupling at the Wtb vertex. The most general lowest dimension, CP-conserving Lagrangian admits right-handed vector and left- or right-handed tensor couplings as well. We find that the data prefer the left-handed vector coupling and set upper limits on the anomalous couplings. These are the first direct constraints on a general Wtb interaction and the first direct limits on left- and right-handed tensor couplings.

Search for neutral Higgs bosons in multi-b-jet events in pp[over] collisions at sqrt[s]=1.96 TeV

Data recorded by the D0 experiment at the Fermilab Tevatron Collider are analyzed to search for neutral Higgs bosons produced in association with b quarks. This production mode can be enhanced in the minimal supersymmetric standard model (MSSM). The search is performed in the three b quark channel using multijet triggered events corresponding to an integrated luminosity of 1 fb(-1). No statistically significant excess of events with respect to the predicted background is observed and limits are set in the MSSM parameter space.

Measurement of the electron charge asymmetry in pp[over ]-->W+X-->enu+X events at sqrt[s]=1.96 TeV

We present a measurement of the electron charge asymmetry in pp[over ]-->W+X-->enu+X events at a center of mass energy of 1.96 TeV using 0.75 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider. The asymmetry is measured as a function of the electron transverse momentum and pseudorapidity in the interval (-3.2, 3.2) and is compared with expectations from next-to-leading order calculations in perturbative quantum chromodynamics. These measurements will allow more accurate determinations of the proton parton distribution functions.