Observation of the baryonic flavor-changing neutral current decay Λb(0)→Λμ+μ-

We report the first observation of the baryonic flavor-changing neutral current decay Λ(b)(0)→Λμ(+)μ(-) with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses a pp collisions data sample corresponding to 6.8 fb(-1) at √s = 1.96 TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for Λ(b)(0)→Λμ(+)μ(-) are measured. We find B(Λ(b)(0)→Λμ(+)μ(-))=[1.73 ± 0.42(stat) ± (syst)] × 10(-6). We also report the first measurement of the differential branching ratio of B(s)(0)→ϕμ(+)μ(-), using 49 signal events. In addition, we report branching ratios for B(+)→K(+)μ(+)μ(-), B(0)→K(0)μ(+)μ(-), and B→K(*)(892)μ(+)μ(-) decays.

Search for New T' particles in final states with large jet multiplicities and missing transverse energy in p p collisions at sqrt[s] = 1.96 TeV

We present a search for a new particle T' decaying to a top quark via T' → t + X, where X goes undetected. We use a data sample corresponding to 5.7 fb(-1) of integrated luminosity of p p collisions with sqrt[s] = 1.96 TeV, collected at Fermilab Tevatron by the CDF II detector. Our search for pair production of T' is focused on the hadronic decay channel, pp → T'T' → tt + XX → bqq b qq + XX. We interpret our results in terms of a model where T' is an exotic fourth generation quark and X is a dark matter particle. The data are consistent with standard model expectations. We set a limit on the generic production of T'T' → tt + XX, excluding the fourth generation exotic quarks T' at 95% confidence level up to m(T') = 400 GeV/c(2) for m(X) ≤ 70 GeV/c(2).

Search for B(s)(0) → μ+ μ- and B(0) → μ+ μ- decays with CDF II

A search has been performed for B(s)(0) → μ+ μ- and B(0) → μ+ μ- decays using 7 fb(-1) of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. The observed number of B(0) candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of B(B(0) → μ+ μ-) < 6.0 × 10(-9) at 95% confidence level. We observe an excess of B(s)(0) candidates. The probability that the background processes alone could produce such an excess or larger is 0.27%. The probability that the combination of background and the expected standard model rate of B(s)(0) → μ+ μ- could produce such an excess or larger is 1.9%. These data are used to determine B(B(s)(0)→ μ+ μ-) = (1.8(-0.9) (+1.1)) × 10(-8) and provide an upper limit of B(B(s)(0) → μ+ μ-) < 4.0 × 10(-8) at 95% confidence level.

ηπ+ π- resonant structure around 1.8 GeV/c(2) and η(1405) in J/ψ → ωηπ+ π-

We present results of a study of the decay J/ψ → ωηπ+ π- using a sample of (225.2 ± 2.8) × 10(6) J/ψ events collected by the BESIII detector, and report the observation of a new process J/ψ → ωX(1870) with a statistical significance of 7.2σ, in which X(1870) decays to a(0)(±)(980)π±. Fitting to ηπ+ π- mass spectrum yields a mass M = 1877.3 ± 6.3(stat)(-7.4)(+3.4)(syst) MeV/c(2), a width Γ = 57 ± 12(stat)(-4)(+19)(syst) MeV/c(2), and a product branching fraction B(J/ψ → ωX) × B(X→a(0)(±)(980)π±) × B(a(0) (±)(980) → ηπ±) = [1.50 ± 0.26(stat)(-0.36)(+0.72) (syst)] × 10(-4). Signals for J/ψ → ωf(1)(1285) and J/ψ → ω η(1405) are also clearly observed and measured.

Search for new physics in high pT like-sign dilepton events at CDF II

We present a search for new physics in events with two high pT leptons of the same electric charge, using data with an integrated luminosity of 6.1 fb(-1). The observed data are consistent with standard model predictions. We set 95% C.L. lower limits on the mass of doubly charged scalars decaying to like-sign dileptons, m(H±±) > 190-245 GeV/c(2), assuming 100% BR to ee, μμ or eμ.

Organic anion transporter 1 (OAT1) involved in renal cell transport of aristolochic acid I

Aristolochic acids (AAs) are a family of structurally related nitrophenanthrene carboxylic acids that are present in medicinal herbs such as Aristolochia species. The organic anion transporters (OATs) of the solute carrier ( SLC22) gene family located in the renal proximal tubules play a key role in the excretion of a variety of exogenous and endogenous compounds. However, it is unclear how AAs permeate into renal epithelial cells. In this regard, we investigated the role of rat OAT1 ([rOAT1] SLC22A6) in the cellular uptake of AAI in vitro and in vivo. A concentration- and time-dependent intracellular accumulation of AAI was observed in rOAT1-transfected human embryonic kidney 293 (HEK293) cells, which was 2- to 6-fold higher than the control cells. There was a significantly increased rate of cellular apoptosis in rOAT1-transfected HEK293 cells than control cells after AAI treatment. Para-aminohippuric acid (PAH) significantly reduced the intracellular accumulation of AAI in rOAT1-transfected HEK293 cells. Administration of AAI for 35 days in rats caused significantly reduced expression of OAT1 in basolateral membrane and declined renal clearance of PAH as well as renal proximal tubule injuries. These findings indicate that AAI is taken up by OAT1, which then exert its intracellular toxic effects on renal proximal tubule cells, which in turn damage functional OAT1 and may further disturb the transport of its substrates.

Measurement of the cross section for prompt isolated diphoton production in pp collisions at square root(s) = 1.96 TeV

This Letter reports a measurement of the cross section of prompt isolated photon pair production in pp collisions at a total energy square root(s)=1.96  TeV using data of 5.36  fb(-1) integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured cross section, differential in basic kinematic variables, is compared with three perturbative QCD predictions, a leading order parton shower calculation and two next-to-leading order calculations. The next-to-leading order calculations reproduce most aspects of the data. By including photon radiation from quarks before and after hard scattering, the parton shower prediction becomes competitive with the next-to-leading order predictions.

Observation of the Ξ(b)(0) baryon

The observation of the bottom, strange baryon Ξ(b)(0) through the decay chain Ξ(b)(0)→Ξ(c)(+)π-, where ΞΞ(c)(+)→Ξ- π+ π+, Ξ-→Λπ-, and Λ→pπ-, is reported by using data corresponding to an integrated luminosity of 4.2  fb(-1) from pp collisions at square root(s)=1.96  TeV recorded with the Collider Detector at Fermilab. A signal of 25.3(-5.4)(+5.6) candidates is observed whose probability of arising from a background fluctuation is 3.6×10(-12), corresponding to 6.8 gaussian standard deviations. The Ξ(b)(0) mass is measured to be 5787.8±5.0(stat)±1.3(syst)  MeV/c2. In addition, the Ξ(b)- baryon is observed through the process Ξ(b)-→Ξ(c)(0)π-, where Ξ(c)(0)→Ξ- π+, Ξ-→Λπ-, and Λ→pπ-.

Observation of χ(c1) decays into vector meson pairs φφ, ωω, and ωφ

Using (106±4)×10⁻⁶ ψ(3686) events accumulated with the BESIII detector at the BEPCII e⁺e⁻ collider, we present the first measurement of decays of χ(c1) to vector meson pairs φφ, ωω, and ωφ. The branching fractions are measured to be (4.4±0.3±0.5)×10⁻⁴, (6.0±0.3±0.7)×10⁻⁴, and (2.2±0.6±0.2)×10⁻⁵, for χ(c1)→φφ, ωω, and ωφ, respectively, which indicates that the hadron helicity selection rule is significantly violated in χ(cJ) decays. In addition, the measurement of χ(cJ)→ωφ provides the first indication of the rate of doubly OZI-suppressed χ(cJ) decay. Finally, we present improved measurements for the branching fractions of χ(c0) and χ(c2) to vector meson pairs.

Search for new dielectron resonances and Randall-Sundrum gravitons at the collider detector at Fermilab

A search for new dielectron-mass resonances using data recorded by the CDF II detector and corresponding to an integrated luminosity of 5.7  fb(-1) is presented. No significant excess over the expected standard model prediction is observed. In this data set, an event with the highest dielectron mass ever observed (960  GeV/c(2)) was recorded. The results are interpreted in the Randall-Sundrum (RS) model. Combined with the 5.4  fb(-1) diphoton analysis, the RS-graviton lower-mass limit for the coupling k/M¯(Pl)=0.1 is 1058  GeV/c(2), making it the strongest limit to date.

Limits on anomalous trilinear gauge couplings in Zγ events from pp¯ collisions at √s=1.96 TeV

Using Zγ candidate events collected by the CDF detector at the Tevatron Collider, we search for potential anomalous (non-standard-model) couplings between the Z boson and the photon. Zγ couplings vanish at tree level and are heavily suppressed at higher orders; hence any evidence of couplings indicates new physics. Measurements are performed using data corresponding to an integrated luminosity of 4.9  fb(-1) in the Z→νν¯ decay channel and 5.1  fb(-1) in the Z→l(+)l(-) (l=μ, e) decay channels. The combination of these measurements provides the most stringent limits to date on Zγ trilinear gauge couplings. Using an energy scale of Λ=1.5  TeV to allow for a direct comparison with previous measurements, we find limits on the CP-conserving parameters that describe Zγ couplings to be |h(3)(γ,Z)|<0.022 and |h(4)(γ,Z)|<0.0009. These results are consistent with standard model predictions.

Laminar shear stress promotes endothelial cell migration and inhibits cell apoptosis in the presence of hydroxyurea

Cell migration plays important roles in both physiological and pathological processes. Recent studies have shown that hydroxyurea, which is an anti-proliferative inhibitor, can affect cell morphology and specific gene expression of endothelial cells (ECs). In vivo, the functions of ECs are modulated by shear stress. It is well known that shear stress can have effects on EC migration by affecting cell morphology, cytoskeletal arrangement and cell-cell junction, and activating mechanosensors, inducing the changes of signaling pathways, and then increasing or decreasing the expression of gene and protein. However, the influences of hydroxyurea on EC function under shear stress are still unclear. In present study, we investigated the effects of hydroxyurea on EC proliferation, apoptosis and migration under laminar shear stress. The results showed that hydroxyurea prevented growth of ECs in a dose-dependent manner. Hydroxyurea at 2 mM completely inhibited the proliferation of ECs. The results also demonstrated that hydroxyurea induced EC apoptosis, but it was inhibited by 15.27 dyn/cm2 laminar shear stress. Furthermore, shear stress induced cell migration in the presence of hydroxyurea. Therefore, 2 mM hydroxyurea, which completely inhibited the proliferation of HUVECs, could be used to eliminate any confounding effect of shear stress on proliferation in shear stress-induced cell migration. These results also do confirm that shear stress plays important roles in achieving and maintaining the stabilization of ECs.

First search for multijet resonances in sqrt(s) = 1.96 TeV pp collisions

We present the first model independent search for three-jet hadronic resonances within multijet events in sqrt(s) = 1.96  TeV pp collisions at the Fermilab Tevatron using the CDF II detector. Pair production of supersymmetric gluinos and squarks with hadronic R-parity violating decays is employed as an example of a new physics benchmark for this signature. Selection criteria based on the kinematic properties of an ensemble of jet combinations within each event help to extract signal from copious QCD background. No significant excess outside the top quark mass window is observed in data with an integrated luminosity of 3.2  fb(-1). We place 95% confidence level limits on the production cross section σ(pp → XX')×BR(gg → 3  jet + 3  jet) where X, X' = g, q, or q, with q, q → g + jet, as a function of gluino mass, in the range of 77  GeV/c2 to 240  GeV/c2.

Search for a very light CP-odd Higgs boson in top quark decays from pp collisions at sqrt(s)]=1.96 TeV

We present the results of a search for a very light CP-odd Higgs boson a(1)(0) originating from top quark decays t → H(±)b → W(±(*)) a(1)(0)b, and subsequently decaying into τ+ τ-. Using a data sample corresponding to an integrated luminosity of 2.7  fb(-1) collected by the CDF II detector in pp collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20  GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t → H(±)b for various masses of H(±) and a(1)(0).

First measurement of the angular coefficients of Drell-Yan e(+)e(-) pairs in the Z mass region from pp¯ collisions at √s=1.96 TeV

We report on the first measurement of the angular distributions of final state electrons in pp¯ → γ*/Z → e(+)e(-) + X events produced in the Z boson mass region at √s1.96 TeV. The data sample collected by the CDF II detector for this result corresponds to 2.1  fb(-1) of integrated luminosity. The angular distributions are studied as a function of the transverse momentum of the electron-positron pair and show good agreement with the Lam-Tung relation, consistent with a spin-1 description of the gluon, and demonstrate that, at high values of the transverse momentum, Z bosons are produced via quark-antiquark annihilation and quark-gluon Compton processes.