Study of CP asymmetry in B^{0}-B[over ¯]^{0} mixing with inclusive dilepton events

We present a measurement of the asymmetry A_{CP} between same-sign inclusive dilepton samples ℓ^{+}ℓ^{+} and ℓ^{-}ℓ^{-} (ℓ=e, μ) from semileptonic B decays in ϒ(4S)→BB[over ¯] events, using the complete data set recorded by the BABAR experiment near the ϒ(4S) resonance, corresponding to 471×10^{6} BB[over ¯] pairs. The asymmetry A_{CP} allows comparison between the mixing probabilities P(B[over ¯]^{0}→B^{0}) and P(B^{0}→B[over ¯]^{0}), and therefore probes CP and T violation. The result, A_{CP}=[-3.9±3.5(stat)±1.9(syst)]×10^{-3}, is consistent with the standard model expectation.

Search for a dark photon in e(+)e(-) collisions at BABAR

Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A^{'}), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e^{+}e^{-}→γA^{'}, A^{'}→e^{+}e^{-}, μ^{+}μ^{-} using 514  fb^{-1} of data collected with the BABAR detector. We observe no statistically significant deviations from the standard model predictions, and we set 90% confidence level upper limits on the mixing strength between the photon and dark photon at the level of 10^{-4}-10^{-3} for dark photon masses in the range 0.02-10.2  GeV. We further constrain the range of the parameter space favored by interpretations of the discrepancy between the calculated and measured anomalous magnetic moment of the muon.

An eight month randomized controlled exercise intervention alters resting state synchrony in overweight children

Children with low aerobic fitness have altered brain function compared to higher-fit children. This study examined the effect of an 8-month exercise intervention on resting state synchrony. Twenty-two sedentary, overweight (body mass index ≥85th percentile) children 8-11 years old were randomly assigned to one of two after-school programs: aerobic exercise (n=13) or sedentary attention control (n=9). Before and after the 8-month programs, all subjects participated in resting state functional magnetic resonance imaging scans. Independent components analysis identified several networks, with four chosen for between-group analysis: salience, default mode, cognitive control, and motor networks. The default mode, cognitive control, and motor networks showed more spatial refinement over time in the exercise group compared to controls. The motor network showed increased synchrony in the exercise group with the right medial frontal gyrus compared to controls. Exercise behavior may enhance brain development in children.

Measurement of the D*(2010)+ meson width and the D*(2010)+ - D0 mass difference

We measure the mass difference Δm0 between the D*(2010)+ and the D0 and the natural linewidth Γ of the transition D*(2010)+ → D0π+. The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ(4S) resonance, and correspond to an integrated luminosity of approximately 477  fb(-1). The D0 is reconstructed in the decay modes D0 → K- π+ and D0 → K- π+ π- π+. For the decay mode D0 → K- π+ we obtain Γ = (83.4±1.7±1.5)  keV and Δm0 = (145425.6±0.6±1.7)  keV, [corrected] where the quoted errors are statistical and systematic, respectively. For the D0 → K- π+ π- π+ mode we obtain Γ = (83.2±1.5±2.6)  keV and Δm0 = (145426.6±0.5±1.9)  keV. [corrected] The combined measurements yield Γ = (83.3±1.2±1.4)  keV and Δm0 = (145425.9±0.4±1.7)  keV; the width is a factor of approximately 12 times more precise than the previous value, while the mass difference is a factor of approximately 6 times more precise.

Search for CP violation in B0-B0 mixing using partial reconstruction of B0→D*- Xℓ+ νℓ and a kaon tag

We present results of a search for CP violation in B0- B0 mixing with the BABAR detector. We select a sample of B0→D*- Xℓ+ ν decays with a partial reconstruction method and use kaon tagging to assess the flavor of the other B meson in the event. We determine the CP violating asymmetry ACP≡[N(B0B0)-N(B0B0)]/[N(B0B0)+N(B0B0)]=(0.06±0.17(-0.32)(+0.38))%, corresponding to ΔCP=1-|q/p|=(0.29±0.84(-1.61)(+1.88))×10(-3).

Observation of time-reversal violation in the B0 meson system

Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B(0) or B(0)), and J/ψK(L)(0) or ccK(S)(0) final states (referred to as B(+) or B(-)), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B(0) → B(-) and B(-) → B(0), as a function of the time difference between the two B decays. Using 468 × 10(6) BB pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS(T)(+) = -1.37 ± 0.14(stat) ± 0.06(syst) and ΔS(T)(-) = 1.17 ± 0.18(stat) ± 0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.

Precision measurement of the B → Xs γ photon energy spectrum, branching fraction, and direct CP asymmetry A(CP)((B → X(s+d)γ)

The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B → X(s)γ plus B → X(d)γ, is studied using a data sample of (382.8 ± 4.2) × 10(6)Υ(4S) → BB decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B → X(s)γ) = (3.21 ± 0.33) × 10(-4) for E(γ) >1.8 GeV and the direct CP asymmetry A(CP) (B → X(s+d)γ) = 0.057 ± 0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.

Simultaneous liver-kidney transplantation: a survey of US transplant centers

Consensus recommendations have been published to help better define those patients who would benefit from simultaneous liver-kidney transplantation (SLK). We conducted a survey of transplant centers that perform SLK (n = 88, 65% response rate) to determine practice patterns in the United States. The majority of centers (73%) stated that they use dialysis duration whereas only 30% of centers use acute kidney injury duration as a criterion for determining need for SLK. Dialysis duration >4 weeks was used by 32% of centers, >6 weeks by 37% and >8 weeks by 32% of centers. Glomerular filtration rate (GFR) was estimated using the modified diet in renal disease (MDRD)-4 equation in roughly half of centers whereas the MDRD-6 equation was used by only 6%. In patients with chronic kidney disease, GFR < 40 mL/min was used by 24% of centers as a criterion for SLK transplants instead of the recommended threshold of < 30 mL/min. Regional differences in practices were also observed. This survey demonstrates significant variation in the criteria used for SLK among transplant centers, with few centers following the current published recommendations, and emphasizes the need for evidence-based guidelines and uniformity in studying renal dysfunction in liver transplant candidates.

Simultaneous liver-kidney transplantation summit: current state and future directions

Although previous consensus recommendations have helped define patients who would benefit from simultaneous liver-kidney transplantation (SLK), there is a current need to reassess published guidelines for SLK because of continuing increase in proportion of liver transplant candidates with renal dysfunction and ongoing donor organ shortage. The purpose of this consensus meeting was to critically evaluate published and registry data regarding patient and renal outcomes following liver transplantation alone or SLK in liver transplant recipients with renal dysfunction. Modifications to the current guidelines for SLK and a research agenda were proposed.

Evidence for an excess of B→D*τ(-)ν(τ) decays

Based on the full BABAR data sample, we report improved measurements of the ratios R(D(*))=B(B[over ¯]→D(*)τ(-)ν[over ¯](τ))/B(B[over ¯]→D(*)ℓ(ℓ)(-)ν[over ¯](ℓ)), where ℓ is either e or μ. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D(*))=0.332±0.024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, our results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model.

A perinatal intervention program for urban american indians part 1: design, implementation, and outcomes

High infant mortality rates among American Indians are disproportionate to state statistics for other races and higher than the national average. These findings prompted a community health center in a large Midwestern city to create and provide an American Indian infant mortality reduction project in the early 1990s. Strategies for program implementation included networking with local organizations, communicating with reservation health clinics throughout the state, educating American Indian mothers and their community about factors contributing to American Indian infant mortality, and providing individual case management to American Indian women and infants. We offer this article for three reasons: This grant project was successful, disparity in rates of infant mortality among peoples of color continues, and a paucity of information exists about the health behaviors of American Indian women.

Search for low-mass dark-sector Higgs bosons

Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516 fb(-1) of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the standard model-dark-sector mixing angle and the dark-sector coupling constant.

Search for hadronic decays of a light Higgs boson in the radiative decay Υ→γA0

We search for hadronic decays of a light Higgs boson (A(0)) produced in radiative decays of an Υ(2S) or Υ(3S) meson, Υ→γA(0). The data have been recorded by the BABAR experiment at the Υ(3S) and Υ(2S) center-of-mass energies and include (121.3±1.2)×10(6) Υ(3S) and (98.3±0.9)×10(6) Υ(2S) mesons. No significant signal is observed. We set 90% confidence level upper limits on the product branching fractions B(Υ(nS)→γA(0))B(A(0)→hadrons) (n=2 or 3) that range from 1×10(-6) for an A(0) mass of 0.3 GeV/c(2) to 8×10(-5) at 7 GeV/c(2).

Observation of the decay B- → D(s)((*)+) K- ℓ- ν(ℓ)

We report the observation of the decay B- → D(s)((*)+) K- ℓ- ν(ℓ) based on 342  fb(-1) of data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e+ e- storage rings at SLAC. A simultaneous fit to three D(s)(+) decay chains is performed to extract the signal yield from measurements of the squared missing mass in the B meson decay. We observe the decay B- → D(s)((*)+) K- ℓ- ν(ℓ) with a significance greater than 5 standard deviations (including systematic uncertainties) and measure its branching fraction to be B(B- → D(s)((*)+) K- ℓ- ν(ℓ)) = [6.13(-1.03)(+1.04)(stat)±0.43(syst)±0.51(B(D(s)))]×10(-4), where the last error reflects the limited knowledge of the D(s) branching fractions.

Search for production of invisible final states in single-photon decays of Υ(1S)

We search for single-photon decays of the Υ(1S) resonance, Υ → γ + invisible, where the invisible state is either a particle of definite mass, such as a light Higgs boson A⁰, or a pair of dark matter particles, χχ. Both A⁰ and χ are assumed to have zero spin. We tag Υ(1S) decays with a dipion transition Υ(2S) → π⁺π⁻Υ(1S) and look for events with a single energetic photon and significant missing energy. We find no evidence for such processes in the mass range m(A⁰) ≤ 9.2 GeV and m(χ) ≤ 4.5 GeV in the sample of 98 × 10⁶ Υ(2S) decays collected with the BABAR detector and set stringent limits on new physics models that contain light dark matter states.

Risk factors for late-onset cytomegalovirus disease in donor seropositive/recipient seronegative kidney transplant recipients who receive antiviral prophylaxis

BACKGROUND

Cytomegalovirus (CMV) disease occurs frequently after cessation of antiviral prophylaxis in CMV-seronegative kidney transplant recipients from seropositive donors (D+R-), and the risk factors are incompletely defined.

METHOD

We retrospectively assessed the incidence, clinical features, and risk factors for CMV disease in a cohort of D+R- kidney transplant recipients who received antiviral prophylaxis at a single US transplant center using descriptive statistics and Cox proportional hazards models.

RESULTS

CMV disease developed in 29 of 113 (26%) D+R- patients at a median of 185 days (interquartile range 116-231 days) post transplant, including CMV syndrome (66%) and tissue invasive disease (34%). The incidence of CMV disease was higher in patients who underwent re-transplantation (57% vs. 24%) and this factor was independently associated with a higher risk of CMV disease in multivariable analysis (hazard ratio, 4.02; 95% confidence interval, 1.3-13; P = 0.016). Other demographic and transplant variables were not independently associated with a risk of late-onset CMV disease.

CONCLUSIONS

Despite a comprehensive analysis of patient and transplant variables, only re-transplantation was identified as a risk factor for CMV disease in D+R- kidney transplant recipients who received antiviral prophylaxis, but had limited clinical predictive value. The development of novel laboratory markers to identify patients at greatest risk for CMV disease should be a priority for future studies.

Search for f(J)(2220) in radiative J/ψ decays

We present a search for f(J)(2220) production in radiative J/ψ→γf(J)(2220) decays using 460  fb⁻¹ of data collected with the BABAR detector at the SLAC PEP-II e(+)e⁻ collider. The f(J)(2220) is searched for in the decays to K(+)K⁻ and K(S)⁰K(S)⁰. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/ψ→γf(J)(2220) and f(J)(2220)→K(+)K⁻(K(S)⁰K(S)⁰) as a function of spin and helicity are set at the level of 10⁻⁵, below the central values reported by the Mark III experiment.

Evidence for direct CP violation in the measurement of the Cabbibo-Kobayashi-Maskawa angle γ with B∓ → D(*)K(*)∓ decays

We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle γ through a Dalitz plot analysis of neutral D-meson decays to K(S)(0) π+ π- and K(S)(0) K+ K- produced in the processes B∓ → DK∓, B∓ D* K∓ with D* → Dπ(0), Dγ, and B∓ → DK*∓ with K*∓ → K(S)(0) π∓, using 468 million BB pairs collected by the BABAR detector at the PEP-II asymmetric-energy e+ e- collider at SLAC. We measure γ = (68 ± 14 ± 4 ± 3)° (modulo 180°), where the first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the uncertainty in the description of the neutral D decay amplitudes. This result is inconsistent with γ = 0 (no direct CP violation) with a significance of 3.5 standard deviations.

Measurement of D0-D0 mixing parameters using D0 → K(S)(0)π+ π- and D0 → K(S)(0)K+ K- decays

We report a direct measurement of D0-D0 mixing parameters through a time-dependent amplitude analysis of the Dalitz plots of D(0) → K(S)(0) π+ π- and, for the first time, D0 → K(S)(0)K+ K- decays. The low-momentum pion π(s)(+) in the decay D*+ → D0 π(s)(+) identifies the flavor of the neutral D meson at its production. Using 468.5 fb(-1) of e+ e- colliding-beam data recorded near square root(s)=10.6 GeV by the BABAR detector at the PEP-II asymmetric-energy collider at SLAC, we measure the mixing parameters x = [1.6 ± 2.3(stat) ± 1.2(syst) ± 0.8(model)] × 10(-3), and y = [5.7 ± 2.0(stat) ± 1.3(syst) ± 0.7(model)] × 10(-3). These results provide the best measurement to date of x and y. The knowledge of the value of x, in particular, is crucial for understanding the origin of mixing.

Measurements of charged current lepton universality and |Vus| using tau lepton decays to e- ν(e) ν(τ), μ- ν(μ) ν(τ), π- ν(τ), and K- ν(τ)

Using 467  fb(-1) of e+e- annihilation data collected with the BABAR detector, we measure (B(τ- → μ- ν(μ) ν(τ)))/(B(τ- → e- ν(e) ν(τ))) =(0.9796±0.0016±0.0036), (B(τ- → π- ν(τ)))/(B(τ- → e- ν(e) ν(τ))) = (0.5945±0.0014±0.0061), and (B(τ- → K- ν(τ)))/(B(τ- → e- ν(e) ν(τ))) = (0.03882±0.00032±0.00057), where the uncertainties are statistical and systematic, respectively. From these precision τ measurements, we test the standard model assumption of μ-e and τ-μ charge current lepton universality and provide determinations of |Vus| experimentally independent of the decay of a kaon.

Uptake and incorporation of thymidine by bacterial isolates from an upwelling environment

Thymidine uptake and incorporation by marine bacterial isolates from an upwelling environment were studied. Of 17 isolates each from upwelled and downwelled water, 1 and 6 isolates, respectively, were found to be negative for [H]thymidine incorporation at a substrate concentration of 19 muM. Strains lacking the ability to take up thymidine were not confined to one genus. The measurable rates of uptake and incorporation by the 34 isolates varied greatly. Studies carried out using starved Vibrio, Pseudomonas, and Cytophaga cells showed that these isolates transported and incorporated thymidine after periods of as long as 5 weeks of nutrient deprivation. This occurred in the absence of any other exogenously supplied nutrients. Overall, these results indicate that not all marine bacteria take up thymidine and that those that do incorporate the nucleoside may do so at very different rates. The assumption that only actively growing or dividing cells incorporate thymidine must be viewed with caution.

Maintenance of Different Mannitol Uptake Systems during Starvation in Oxidative and Fermentative Marine Bacteria

The mannitol uptake systems in marine Vibrio and Pseudomonas isolates from the kelp beds off the South African west coast were examined. The fermentative Vibrio isolate possessed a constitutive rapid mannitol uptake system and also a soluble mannitol-1-phosphate dehydrogenase, indicative of a mannitol phosphotransferase system. An inducible, relatively less active mannitol uptake system was detected in the oxidative Pseudomonas isolate, and this strain possessed a mannitol dehydrogenase. The maintenance of these systems during starvation survival was studied. The Vibrio isolate maintained its initial uptake system for approximately 5 weeks of starvation, after which time the uptake system was replaced by one with a higher affinity for mannitol. The mannitol transport system of the Pseudomonas isolate was depressed early in starvation (30 h) but could be readily induced by exogenous mannitol after 6 weeks of starvation. The relative proportions of mannitol which was incorporated and respired were determined in starved Vibrio and Pseudomonas strains.

Test of lepton universality in Υ(1S) decays at BABAR

The ratio R(τμ)(Υ(1S))=Γ(Υ(1S)→τ+ τ-)/Γ(Υ(1S)→μ+ μ-) is measured using a sample of (121.8±1.2)×10(6)Υ(3S) events recorded by the BABAR detector. This measurement is intended as a test of lepton universality and as a search for a possible light pseudoscalar Higgs boson. In the standard model (SM) this ratio is expected to be close to 1. Any significant deviations would violate lepton universality and could be introduced by the coupling to a light pseudoscalar Higgs boson. The analysis studies the decays Υ(3S)→Υ(1S)π+ π-, Υ(1S)→l+ l-, where l=μ, τ. The result, R(τμ)(Υ(1S))=1.005±0.013(stat)±0.022(syst), shows no deviation from the expected SM value, while improving the precision with respect to previous measurements.

Search for charged lepton flavor violation in narrow upsilon decays

Charged-lepton flavor-violating processes are unobservable in the standard model, but they are predicted to be enhanced in several extensions to the standard model, including supersymmetry and models with leptoquarks or compositeness. We present a search for such processes in a sample of 99x10(6)Upsilon(2S) decays and 117x10(6)Upsilon(3S) decays collected with the BABAR detector. We place upper limits on the branching fractions B(Upsilon(nS)-->e(+/-)tau(-/+)) and B(Upsilon(nS)-->mu(+/-)tau(-/+)) (n=2,3) at the 10(-6) level and use these results to place lower limits of order 1 TeV on the mass scale of charged-lepton flavor-violating effective operators.

Searches for Lepton flavor violation in the decays tau{+/-}-->e{+/-}gamma and tau{+/-}-->mu{+/-}gamma

Searches for lepton-flavor-violating decays of a tau lepton to a lighter mass lepton and a photon have been performed with the entire data set of (963+/-7)x10{6} tau decays collected by the BABAR detector near the Upsilon(4S), Upsilon(3S) and Upsilon(2S) resonances. The searches yield no evidence of signals and we set upper limits on the branching fractions of B(tau{+/-}-->e{+/-}gamma)<3.3x10{-8} and B(tau{+/-}-->mu{+/-}gamma)<4.4x10{-8} at 90% confidence level.