Search for supersymmetry with like-sign lepton-tau events at CDF

We present a search for chargino-neutralino associated production using like electric charge dilepton events collected by the CDF II detector at the Fermilab Tevatron in proton-antiproton collisions at sqrt[s] = 1.96 TeV. One lepton is identified as the hadronic decay of a tau lepton, while the other is an electron or muon. In data corresponding to 6.0 fb(-1) of integrated luminosity, we obtain good agreement with standard model predictions and set limits on the chargino-neutralino production cross section for simplified gravity- and gauge-mediated models. As an example, assuming that the chargino and neutralino decays to taus dominate, in the simplified gauge-mediated model we exclude cross sections greater than 300 fb at 95% credibility level for chargino and neutralino masses of 225 GeV/c(2). This analysis is the first to extend the LHC searches for electroweak supersymmetric production of gauginos to high tanβ and slepton next-to-lightest supersymmetric particle scenarios.

Denis RD, Stahlman J, Stamen R, Stanecka E, Stanek RW, Stanescu C, Stanescu-Bellu M, Stanitzki MM, Stapnes S, Starchenko EA, Stark J, Staroba P, Starovoitov P, Staszewski R, Staude A, Stavina P, Steele G, Steinbach P, Steinberg P, Stekl I, Stelzer B, Stelzer HJ, Stelzer-Chilton O, Stenzel H, Stern S, Stewart GA, Stillings JA, Stockton MC, Stoebe M, Stoerig K, Stoicea G, Stonjek S, Strachota P, Stradling AR, Straessner A, Strandberg J, Strandberg S, Strandlie A, Strang M, Strauss E, Strauss M, Strizenec P, Ströhmer R, Strom DM, Strong JA, Stroynowski R, Stugu B, Stumer I, Stupak J, Sturm P, Styles NA, Su D, Subramania HS, Subramaniam R, Succurro A, Sugaya Y, Suhr C, Suk M, Sulin VV, Sultansoy S, Sumida T, Sun X, Sundermann JE, Suruliz K, Susinno G, Sutton MR, Suzuki Y, Suzuki Y, Svatos M, Swedish S, Swiatlowski M, Sykora I, Sykora T, Ta D, Tackmann K, Taffard A, Tafirout R, Taiblum N, Takahashi Y, Takai H, Takashima R, Takeda H, Takeshita T, Takubo Y, Talby M, Talyshev A, Tam JYC, Tamsett MC, Tan KG, Tanaka J, Tanaka R, Tanaka S, Tanaka S, Tanasijczuk AJ, Tani K, Tannoury N, Tapprogge S, Tardif D, Tarem S, Tarrade F, Tartarelli GF, Tas P, Tasevsky M, Tassi E, Tayalati Y, Taylor C, Taylor FE, Taylor GN, Taylor W, Teinturier M, Teischinger FA, Teixeira Dias Castanheira M, Teixeira-Dias P, Temming KK, Ten Kate H, Teng PK, Terada S, Terashi K, Terron J, Testa M, Teuscher RJ, Therhaag J, Theveneaux-Pelzer T, Thoma S, Thomas JP, Thompson EN, Thompson PD, Thompson PD, Thompson AS, Thomsen LA, Thomson E, Thomson M, Thong WM, Thun RP, Tian F, Tibbetts MJ, Tic T, Tikhomirov VO, Tikhonov YA, Timoshenko S, Tiouchichine E, Tipton P, Tisserant S, Todorov T, Todorova-Nova S, Toggerson B, Tojo J, Tokár S, Tokushuku K, Tollefson K, Tomlinson L, Tomoto M, Tompkins L, Toms K, Tonoyan A, Topfel C, Topilin ND, Torrence E, Torres H, Torró Pastor E, Toth J, Touchard F, Tovey DR, Tran HL, Trefzger T, Tremblet L, Tricoli A, Trigger IM, Trincaz-Duvoid S, Tripiana MF, Triplett N, Trischuk W, Trocmé B, Troncon C, Trottier-McDonald M, Trovatelli M, True P, Trzebinski M, Trzupek A, Tsarouchas C, Tseng JCL, Tsiakiris M, Tsiareshka PV, Tsionou D, Tsipolitis G, Tsiskaridze S, Tsiskaridze V, Tskhadadze EG, Tsukerman II, Tsulaia V, Tsung JW, Tsuno S, Tsybychev D, Tua A, Tudorache A, Tudorache V, Tuggle JM, Turala M, Turecek D, Turk Cakir I, Turra R, Tuts PM, Tykhonov A, Tylmad M, Tyndel M, Tzanakos G, Uchida K, Ueda I, Ueno R, Ughetto M, Ugland M, Uhlenbrock M, Ukegawa F, Unal G, Undrus A, Unel G, Ungaro FC, Unno Y, Urbaniec D, Urquijo P, Usai G, Vacavant L, Vacek V, Vachon B, Vahsen S, Valencic N, Valentinetti S, Valero A, Valery L, Valkar S, Valladolid Gallego E, Vallecorsa S, Valls Ferrer JA, Van Berg R, Van Der Deijl PC, van der Geer R, van der Graaf H, Van Der Leeuw R, van der Poel E, van der Ster D, van Eldik N, van Gemmeren P, Van Nieuwkoop J, van Vulpen I, Vanadia M, Vandelli W, Vaniachine A, Vankov P, Vannucci F, Vari R, Varnes EW, Varol T, Varouchas D, Vartapetian A, Varvell KE, Vassilakopoulos VI, Vazeille F, Vazquez Schroeder T, Veloso F, Veneziano S, Ventura A, Ventura D, Venturi M, Venturi N, Vercesi V, Verducci M, Verkerke W, Vermeulen JC, Vest A, Vetterli MC, Vichou I, Vickey T, Vickey Boeriu OE, Viehhauser GHA, Viel S, Villa M, Villaplana Perez M, Vilucchi E, Vincter MG, Vinek E, Vinogradov VB, Virzi J, Vitells O, Viti M, Vivarelli I, Vives Vaque F, Vlachos S, Vladoiu D, Vlasak M, Vogel A, Vokac P, Volpi G, Volpi M, Volpini G, von der Schmitt H, von Radziewski H, von Toerne E, Vorobel V, Vorwerk V, Vos M, Voss R, Vossebeld JH, Vranjes N, Vranjes Milosavljevic M, Vrba V, Vreeswijk M, Vu Anh T, Vuillermet R, Vukotic I, Vykydal Z, Wagner W, Wagner P, Wahlen H, Wahrmund S, Wakabayashi J, Walch S, Walder J, Walker R, Walkowiak W, Wall R, Waller P, Walsh B, Wang C, Wang H, Wang H, Wang J, Wang J, Wang K, Wang R, Wang SM, Wang T, Wang X, Warburton A, Ward CP, Wardrope DR, Warsinsky M, Washbrook A, Wasicki C, Watanabe I, Watkins PM, Watson AT, Watson IJ, Watson MF, Watts G, Watts S, Waugh AT, Waugh BM, Weber MS, Webster JS, Weidberg AR, Weigell P, Weingarten J, Weiser C, Wells PS, Wenaus T, Wendland D, Weng Z, Wengler T, Wenig S, Wermes N, Werner M, Werner P, Werth M, Wessels M, Wetter J, Weydert C, Whalen K, White A, White MJ, White S, Whitehead SR, Whiteson D, Whittington D, Wicke D, Wickens FJ, Wiedenmann W, Wielers M, Wienemann P, Wiglesworth C, Wiik-Fuchs LAM, Wijeratne PA, Wildauer A, Wildt MA, Wilhelm I, Wilkens HG, Will JZ, Williams E, Williams HH, Williams S, Willis W, Willocq S, Wilson JA, Wilson MG, Wilson A, Wingerter-Seez I, Winkelmann S, Winklmeier F, Wittgen M, Wittig T, Wittkowski J, Wollstadt SJ, Wolter MW, Wolters H, Wong WC, Wooden G, Wosiek BK, Wotschack J, Woudstra MJ, Wozniak KW, Wraight K, Wright M, Wrona B, Wu SL, Wu X, Wu Y, Wulf E, Wynne BM, Xella S, Xiao M, Xie S, Xu C, Xu D, Xu L, Yabsley B, Yacoob S, Yamada M, Yamaguchi H, Yamaguchi Y, Yamamoto A, Yamamoto K, Yamamoto S, Yamamura T, Yamanaka T, Yamauchi K, Yamazaki T, Yamazaki Y, Yan Z, Yang H, Yang H, Yang UK, Yang Y, Yang Z, Yanush S, Yao L, Yasu Y, Yatsenko E, Ye J, Ye S, Yen AL, Yilmaz M, Yoosoofmiya R, Yorita K, Yoshida R, Yoshihara K, Young C, Young CJS, Youssef S, Yu D, Yu DR, Yu J, Yu J, Yuan L, Yurkewicz A, Zabinski B, Zaidan R, Zaitsev AM, Zambito S, Zanello L, Zanzi D, Zaytsev A, Zeitnitz C, Zeman M, Zemla A, Zenin O, Ženiš T, Zerwas D, Zevi della Porta G, Zhang D, Zhang H, Zhang J, Zhang L, Zhang X, Zhang Z, Zhao L, Zhao Z, Zhemchugov A, Zhong J, Zhou B, Zhou N, Zhou Y, Zhu CG, Zhu H, Zhu J, Zhu Y, Zhuang X, Zhuravlov V, Zibell A, Zieminska D, Zimin NI, Zimmermann R, Zimmermann S, Zimmermann S, Zinonos Z, Ziolkowski M, Zitoun R, Živković L, Zmouchko VV, Zobernig G, Zoccoli A, zur Nedden M, Zutshi V, Zwalinski L. Measurement of kT splitting scales in W→ℓν events at [Formula: see text] with the ATLAS detector

A measurement of splitting scales, as defined by the kT clustering algorithm, is presented for final states containing a W boson produced in proton-proton collisions at a centre-of-mass energy of 7 TeV. The measurement is based on the full 2010 data sample corresponding to an integrated luminosity of 36 pb-1 which was collected using the ATLAS detector at the CERN Large Hadron Collider. Cluster splitting scales are measured in events containing W bosons decaying to electrons or muons. The measurement comprises the four hardest splitting scales in a kT cluster sequence of the hadronic activity accompanying the W boson, and ratios of these splitting scales. Backgrounds such as multi-jet and top-quark-pair production are subtracted and the results are corrected for detector effects. Predictions from various Monte Carlo event generators at particle level are compared to the data. Overall, reasonable agreement is found with all generators, but larger deviations between the predictions and the data are evident in the soft regions of the splitting scales.

Observation of associated near-side and away-side long-range correlations in sqrt[s(NN)]=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δø) and pseudorapidity (Δη) are measured in sqrt[s(NN)] = 5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb(-1) of data as a function of transverse momentum (p(T)) and the transverse energy (ΣE(T)(Pb)) summed over 3.1 < η < 4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2 < |Δ η | < 5) "near-side" (Δø ~ 0) correlation that grows rapidly with increasing ΣE(T)(Pb). A long-range "away-side" (Δø ~ π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣE(T)(Pb), is found to match the near-side correlation in magnitude, shape (in Δη and Δø) and ΣE(T)(Pb) dependence. The resultant Δø correlation is approximately symmetric about π/2, and is consistent with a dominant cos2Δø modulation for all ΣE(T)(Pb) ranges and particle p(T).

Multi-channel search for squarks and gluinos in [Formula: see text]pp collisions with the ATLAS detector at the LHC

A search for supersymmetric particles in final states with zero, one, and two leptons, with and without jets identified as originating from b-quarks, in 4.7 fb-1 of [Formula: see text]pp collisions produced by the Large Hadron Collider and recorded by the ATLAS detector is presented. The search uses a set of variables carrying information on the event kinematics transverse and parallel to the beam line that are sensitive to several topologies expected in supersymmetry. Mutually exclusive final states are defined, allowing a combination of all channels to increase the search sensitivity. No deviation from the Standard Model expectation is observed. Upper limits at 95 % confidence level on visible cross-sections for the production of new particles are extracted. Results are interpreted in the context of the constrained minimal supersymmetric extension to the Standard Model and in supersymmetry-inspired models with diverse, high-multiplicity final states.

Search for resonant top-antitop production in the lepton plus jets decay mode using the full CDF data set

This Letter reports a search for a narrow resonant state decaying into two W bosons and two b quarks where one W boson decays leptonically and the other decays into a quark-antiquark pair. The search is particularly sensitive to top-antitop resonant production. We use the full data sample of proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, corresponding to an integrated luminosity of 9.45 fb(-1). No evidence for resonant production is found, and upper limits on the production cross section times branching ratio for a narrow resonant state are extracted. Within a specific benchmark model, we exclude a Z' boson with mass, M(Z'), below 915 GeV/c(2) decaying into a top-antitop pair at the 95% credibility level assuming a Z' boson decay width of Γ(Z') = 0.012 M(Z'). This is the most sensitive search for a narrow qq-initiated tt resonance in the mass region below 750 GeV/c(2).

Search for a two-Higgs-boson doublet using a simplified model in pp collisions at sqrt[s] = 1.96 TeV

We present a search for new particles in an extension to the standard model that includes a heavy Higgs boson (H(0)), a lighter charged Higgs boson (H(±)), and an even lighter Higgs boson h(0), with decays leading to a W-boson pair and a bottom-antibottom quark pair in the final state. We use events with exactly one lepton, missing transverse momentum, and at least four jets in data corresponding to an integrated luminosity of 8.7 fb(-1) collected by the CDF II detector in proton-antiproton collisions at sqrt[s]= 1.96 TeV. We find the data to be consistent with standard model predictions and report the results in terms of a simplified Higgs-cascade-decay model, setting 95% confidence level upper limits on the product of cross section and branching fraction from 1.3 pb to 15 fb as a function of H(0) and H(±) masses for m(h)(0) = 126 GeV/c(2).

Measurement of the cross section for prompt isolated diphoton production using the full CDF run II data sample

This Letter reports a measurement of the cross section for producing pairs of central prompt isolated photons in proton-antiproton collisions at a total energy sqrt[s] = 1.96 TeV using data corresponding to 9.5 fb(-1) integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured differential cross section is compared to three calculations derived from the theory of strong interactions. These include a prediction based on a leading order matrix element calculation merged with a parton shower model, a next-to-leading order calculation, and a next-to-next-to-leading order calculation. The first and last calculations reproduce most aspects of the data, thus showing the importance of higher-order contributions for understanding the theory of strong interaction and improving measurements of the Higgs boson and searches for new phenomena in diphoton final states.

Observation of the production of a W boson in association with a single charm quark

The first observation of the production of a W boson with a single charm quark (c) jet in pp[over ¯] collisions at √s=1.96  TeV is reported. The analysis uses data corresponding to 4.3  fb(-1), recorded with the CDF II detector at the Fermilab Tevatron. Charm quark candidates are selected through the identification of an electron or muon from charm-hadron semileptonic decay within a hadronic jet, and a Wc signal is observed with a significance of 5.7 standard deviations. The production cross section σ(Wc)(p(Tc)>20  GeV/c,|η(c)|<1.5)×B(W→ℓν) is measured to be 13.6(-3.1)(+3.4)  pb and is in agreement with theoretical expectations. From this result the magnitude of the quark-mixing matrix element V(cs) is derived, |V(cs)|=1.08±0.16 along with a lower limit of |V(cs)|>0.71 at the 95% confidence level, assuming that the Wc production through c to s quark coupling is dominant.

Measurements of the top-quark mass and the tt cross section in the hadronic τ+jets decay channel at sqrt[s] = 1.96 TeV

We present the first direct measurement of the top-quark mass using tt events decaying in the hadronic τ+jets decay channel. Using data corresponding to an integrated luminosity of 2.2 fb(-1) collected by the CDF II detector in pp collisions at sqrt[s] = 1.96 TeV at the Fermilab Tevatron, we measure the tt cross section, σ(tt), and the top-quark mass, M(top). We extract M(top) from a likelihood based on per-event probabilities calculated with leading-order signal and background matrix elements. We measure σ(tt) = 8.8 ± 3.3(stat) ± 2.2(syst) pb and M(top) = 172.7 ± 9.3(stat) ± 3.7(syst) GeV/c(2).

Search for the standard model Higgs Boson produced in association with top quarks using the full CDF data set

A search is presented for the standard model Higgs boson produced in association with top quarks using the full Run II proton-antiproton collision data set, corresponding to 9.45 fb(-1), collected by the Collider Detector at Fermilab. No significant excess over the expected background is observed, and 95% credibility-level upper bounds are placed on the cross section σ(ttH → lepton + missing transverse energy+jets). For a Higgs boson mass of 125 GeV/c(2), we expect to set a limit of 12.6 and observe a limit of 20.5 times the standard model rate. This represents the most sensitive search for a standard model Higgs boson in this channel to date.

Measurement of the bottom-strange meson mixing phase in the full CDF data set

We report a measurement of the bottom-strange meson mixing phase β(s) using the time evolution of B(s)(0)→J/ψ(→μ(+)μ(-))φ(→K(+)K(-)) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at √s=1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb(-1) of integrated luminosity. We report confidence regions in the two-dimensional space of β(s) and the B(s)(0) decay-width difference ΔΓ(s) and measure β(s)∈[-π/2,-1.51]∪[-0.06,0.30]∪[1.26,π/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of β(s), we also determine ΔΓ(s)=0.068±0.026(stat)±0.009(syst) ps(-1) and the mean B(s)(0) lifetime τ(s)=1.528±0.019(stat)±0.009(syst) ps, which are consistent and competitive with determinations by other experiments.

Precision top-quark mass measurement at CDF

We present a precision measurement of the top-quark mass using the full sample of Tevatron √s = 1.96 TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb(-1). Using a sample of tt¯ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the W boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with in situ calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, M(top)=172.85±0.71(stat)±0.85(syst) GeV/c(2).

Expression and tyrosine phosphorylation of phosphatidyl-inositol-3 kinase in human gastric-cancer cells - its correlation with cell-growth

To reveal the signaling pathway leading to oncogenecity of human cancer cells, we examined the expression and tyrosine-phosphorylation of phosphatidylinositol (PI)-3 kinase in cancer cell lines. Of the 14 cell lines examined, two poorly differentiated human gastric cancer cell lines, NUGC-4 and MKN-45, which were previously found to have aberrant elevation of tyrosine phosphorylation showed elevated levels of PI-3 kinase 85-kDa subunit expression. In these cells, tyrosine-phosphorylation and overall activity of PI-3 kinase were apparently elevated, compared with normal human fibroblasts and another well differentiated gastric cancer cell line, MKN-28. Treatment of these cells with tyrosine kinase inhibitor, genistein, strongly suppressed the PI-3 kinase activity. Furthermore, wortmannin, a potent inhibitor of PI-3 kinase, strongly suppressed the growth of these gastric cancer cells. These results suggest that the growth signaling via tyrosine phosphorylation is required for the activation of PI-3 kinase in NUGC4 and MKN-45, and that this activation plays an important role in oncogenic growth of these cells. However, these two cell lines showed different responses of PI-3 kinase to acid-treatment and tyrosine kinase inhibitors. In MKN-45, activation of PI-3 kinase appeared to be constitutive, and could be relevant to the oncogenic nature of the cell line.

Search for the standard model Higgs boson decaying to a bb pair in events with one charged lepton and large missing transverse energy using the full CDF data set

We present a search for the standard model Higgs boson produced in association with a W boson in sqrt[s]=1.96  TeV pp collision data collected with the CDF II detector at the Tevatron corresponding to an integrated luminosity of 9.45  fb(-1). In events consistent with the decay of the Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the WH production cross section times the H→bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125  GeV/c(2), we observe (expect) a limit of 4.9 (2.8) times the standard model value.

Measurement of the difference in CP-violating asymmetries in D(0)→K(+)K(-) and D(0)→π(+)π(-) decays at CDF

We report a measurement of the difference (ΔA(CP)) between time-integrated CP-violating asymmetries in D(0)→K(+)K(-) and D(0)→π(+)π(-) decays reconstructed in the full data set of proton-antiproton collisions collected by the Collider Detector at Fermilab, corresponding to 9.7  fb(-1) of integrated luminosity. The strong decay D(*+)→D(0)π(+) is used to identify the charm meson at production as D(0) or D[over ¯](0). We measure ΔA(CP)=[-0.62±0.21(stat)±0.10(syst)]%, which differs from zero by 2.7 Gaussian standard deviations. This result supports similar evidence for CP violation in charm-quark decays obtained in proton-proton collisions.

Combined search for the standard model Higgs boson decaying to a bb pair using the full CDF data set

We combine the results of searches for the standard model (SM) Higgs boson based on the full CDF Run II data set obtained from sqrt[s]=1.96  TeV pp collisions at the Fermilab Tevatron corresponding to an integrated luminosity of 9.45  fb(-1). The searches are conducted for Higgs bosons that are produced in association with a W or Z boson, have masses in the range 90-150  GeV/c(2), and decay into bb pairs. An excess of data is present that is inconsistent with the background prediction at the level of 2.5 standard deviations (the most significant local excess is 2.7 standard deviations).

Search for the standard model Higgs boson decaying to a bb pair in events with no charged leptons and large missing transverse energy using the full CDF data set

We report on a search for the standard model Higgs boson produced in association with a vector boson in the full data set of proton-antiproton collisions at sqrt[s]=1.96  TeV recorded by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45  fb(-1). We consider events having no identified charged lepton, a transverse energy imbalance, and two or three jets, of which at least one is consistent with originating from the decay of a b quark. We place 95% credibility level upper limits on the production cross section times standard model branching fraction for several mass hypotheses between 90 and 150  GeV/c(2). For a Higgs boson mass of 125  GeV/c(2), the observed (expected) limit is 6.7 (3.6) times the standard model prediction.

Search for the standard model Higgs boson decaying to a bb pair in events with two oppositely charged leptons using the full CDF data set

We present a search for the standard model Higgs boson produced in association with a Z boson in data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45  fb(-1). In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electron or muon pairs, we set 95% credibility level upper limits on the ZH production cross section times the H→bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125  GeV/c(2), we observe (expect) a limit of 7.1 (3.9) times the standard model value.

Evidence for a particle produced in association with weak bosons and decaying to a bottom-antibottom quark pair in higgs boson searches at the tevatron

We combine searches by the CDF and D0 Collaborations for the associated production of a Higgs boson with a W or Z boson and subsequent decay of the Higgs boson to a bottom-antibottom quark pair. The data, originating from Fermilab Tevatron pp collisions at √s = 1.96 TeV, correspond to integrated luminosities of up to 9.7 fb(-1). The searches are conducted for a Higgs boson with mass in the range 100-150 GeV/c(2). We observe an excess of events in the data compared with the background predictions, which is most significant in the mass range between 120 and 135 GeV/c(2). The largest local significance is 3.3 standard deviations, corresponding to a global significance of 3.1 standard deviations. We interpret this as evidence for the presence of a new particle consistent with the standard model Higgs boson, which is produced in association with a weak vector boson and decays to a bottom-antibottom quark pair.

Influence of 50-nm polystyrene particles in inducing cytotoxicity in mice co-injected with carbon tetrachloride, cisplatin, or paraquat

The toxicity of nanomaterials has yet to be fully investigated. In particular, the interactions between nanomaterials and therapeutic drugs require further study. We investigated whether nano-sized polystyrene particles affect drug-induced toxicity. The particles, which are widely used industrially, had diameters of 50 (NPP50), 200 (NPP200) or 1000 (NPP1000) nm. The toxic chemicals tested were carbon tetrachloride, cisplatin (a popular anti-tumor agent), and a widely used herbicide, paraquat. Mice were treated intraperitoneally with either carbon tetrachloride (0.01 ml/kg), cisplatin (100 micromol/kg) or paraquat (50 mg/kg), with or without intravenous administration of polystyrene particles. All treatments in the absence of the nanoparticles were non-lethal and did not result in severe toxicity. However, when mice were injected with paraquat or cisplatin together with polystyrene particles, synergistic, enhanced toxicity was observed in mice injected with NPP50. These synergic effects were not observed in mice co-injected with NPP200 or NPP1000. These findings suggest that further evaluation of the interactions between polystyrene nano-particles and drugs is a critical prerequisite to the pharmaceutical application of nanotechnology.

Search for dark matter in events with one jet and missing transverse energy in pp¯ collisions at √s=1.96 TeV

We present the results of a search for dark matter production in the monojet signature. We analyze a sample of Tevatron pp[over ¯] collisions at √s=1.96 TeV corresponding to an integrated luminosity of 6.7 fb(-1) recorded by the CDF II detector. In events with large missing transverse energy and one energetic jet, we find good agreement between the standard model prediction and the observed data. We set 90% confidence level upper limits on the dark matter production rate. The limits are translated into bounds on nucleon-dark matter scattering rates which are competitive with current direct detection bounds on spin-independent interaction below a dark matter candidate mass of 5 GeV/c(2), and on spin-dependent interactions up to masses of 200 GeV/c(2).

Search for a heavy particle decaying to a top quark and a light quark in pp ¯ collisions at √s=1.96 TeV

We present a search for a new heavy particle X produced in association with a top quark, pp[over ¯]→t(X→t[over ¯]q) or pp[over ¯]→t[over ¯](X[over ¯]→tq[over ¯]), where q stands for up quarks and down quarks. Such a particle may explain the recent anomalous measurements of top-quark forward-backward asymmetry. If the light-flavor quark (q) is reconstructed as a jet (j), this gives a t[over ¯]+j or t+j resonance in tt[over ¯]+jet events, a previously unexplored experimental signature. In a sample of events with exactly one lepton, missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb(-1) collected by the CDF II detector, we find the data to be consistent with the standard model. We set cross-section upper limits on the production (pp[over ¯]→Xt or X[over ¯]t[over ¯]) at 95% confidence level from 0.61 pb to 0.02 pb for X masses ranging from 200 GeV/c(2) to 800 GeV/c(2), respectively.

Evidence for the charmless annihilation decay mode B(s)(0)→π(+)π(-)

We search for annihilation decay modes of neutral b mesons into pairs of charmless charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 6 fb(-1) of integrated luminosity, we obtain the first evidence for the B(s)(0)→π(+)π(-) decay, with a significance of 3.7σ, and a measured branching ratio B(B(s)(0)→π(+)π(-))=(0.57±0.15(stat)±0.10(syst))×10(-6). A search for the B(0)→K(+)K(-) mode in the same sample yields a significance of 2.0σ, and a central value estimate B(B(0)→K(+)K(-))=(0.23±0.10(stat)±0.10(syst))×10(-6).

Measurement of Bs0→Ds(*)+Ds(*)- branching ratios

The decays Bs0→Ds(*)+Ds(*)- are reconstructed in a data sample corresponding to an integrated luminosity of 6.8  fb-1 collected by the CDF II detector at the Tevatron pp[over ¯] collider. All decay modes are observed with a significance of more than 10σ, and we measure the Bs0 production rate times Bs0→Ds(*)+Ds(*)- branching ratios relative to the normalization mode B0→Ds+D-to be 0.183±0.021±0.017 for Bs0→Ds+Ds-, 0.424±0.046±0.035 for Bs0→Ds*±Ds^∓, 0.654±0.072±0.065 for Bs0→Ds*+Ds*-, and 1.261±0.095±0.112 for the inclusive decay Bs0→Ds(*)+Ds(*)-, where the uncertainties are statistical and systematic. These results are the most precise single measurements to date and provide important constraints for indirect searches for nonstandard model physics in Bs0 mixing.

Search for a dark matter candidate produced in association with a single top quark in pp collisions at √[s]=1.96 TeV

We report a new search for dark matter in a data sample of an integrated luminosity of 7.7  fb-1 of Tevatron pp[over ¯] collisions at √[s]=1.96  TeV, collected by the CDF II detector. We search for production of a dark-matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process pp[over ¯]→t+D as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0-150  GeV/c2.

Search for a low-mass standard model Higgs boson in the ττ decay channel in pp collisions at sqrt[s]=1.96 TeV

We report on a search for the standard model Higgs boson decaying into pairs of τ leptons in pp collisions produced by the Tevatron at sqrt[s]=1.96  TeV. The analyzed data sample was recorded by the CDFII detector and corresponds to an integrated luminosity of 6.0  fb(-1). The search is performed in the final state with one τ decaying leptonically and the second one identified through its semihadronic decay. Since no significant excess is observed, a 95% credibility level upper limit on the production cross section times branching ratio to the ττ final state is set for hypothetical Higgs boson masses between 100 and 150  GeV/c2. For a Higgs boson of 120  GeV/c2 the observed (expected) limit is 14.6 (15.3) the predicted value.

Measurements of the angular distributions of muons from Υ decays in pp collisions at sqrt[s] = 1.96 TeV

The angular distributions of muons from Υ(1S,2S,3S) → μ+ μ- decays are measured using data from pp collisions at sqrt[s] = 1.96  TeV corresponding to an integrated luminosity of 6.7  fb(-1) and collected with the CDF II detector at the Fermilab Tevatron. This analysis is the first to report the full angular distributions as functions of transverse momentum p(T) for Υ mesons in both the Collins-Soper and s-channel helicity frames. This is also the first measurement of the spin alignment of Υ(3S) mesons. Within the kinematic range of Υ rapidity |y|<0.6 and p(T) up to 40  GeV/c, the angular distributions are found to be nearly isotropic.

Precise measurement of the W-boson mass with the CDF II detector

We have measured the W-boson mass M(W) using data corresponding to 2.2  fb(-1) of integrated luminosity collected in pp collisions at sqrt[s] = 1.96  TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470,126 W → eν candidates and 624,708 W → μν candidates yield the measurement M(W) = 80,387 ± 12(stat.) ± 15(syst.) = 80,387 ± 19  MeV/c2. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined.

Measurement of ZZ production in leptonic final states at sqrt[s] of 1.96 TeV at CDF

In this Letter, we present a precise measurement of the total ZZ production cross section in pp collisions at sqrt[s]=1.96  TeV, using data collected with the CDF II detector corresponding to an integrated luminosity of approximately 6  fb(-1). The result is obtained by combining separate measurements in the four-charged (ℓℓℓ' ℓ') and two-charged-lepton and two-neutral-lepton (ℓℓνν) decay modes of the Z boson pair. The combined measured cross section for pp → ZZ is 1.64(-0.38)(+0.44)  pb. This is the most precise measurement of the ZZ production cross section in 1.96 TeV pp collisions to date.

Observation of exclusive γγ production in pp¯ collisions at √s=1.96 TeV

We have observed exclusive γγ production in proton-antiproton collisions at √s=1.96 TeV, using data from 1.11±0.07 fb(-1) integrated luminosity taken by the Run II Collider Detector at Fermilab. We selected events with two electromagnetic showers, each with transverse energy E(T)>2.5 GeV and pseudorapidity |η|<1.0, with no other particles detected in -7.4<η<+7.4. The two showers have similar E(T) and azimuthal angle separation Δφ~π; 34 events have two charged particle tracks, consistent with the QED process pp¯→p+e(+)e(-)+p¯ by two-photon exchange, while 43 events have no charged tracks. The number of these events that are exclusive π(0)π(0) is consistent with zero and is <15 at 95% C.L. The cross section for pp¯→p+γγ+p¯ with |η(γ)|<1.0 and E(T)(γ)>2.5 GeV is 2.48(-0.35)(+0.40)(stat)(-0.51)(+0.40)(syst) pb.

Measurements of the angular distributions in the decays B→K(*)μ(+)μ(-) at CDF

We report an indirect search for nonstandard model physics using the flavor-changing neutral current decays B→K(*)μ(+)μ(-). We reconstruct the decays and measure their angular distributions, as a function of q(2)=M(μμ)(2)c(2), where M(μμ) is the dimuon mass, in pp¯ collisions at √s=1.96 TeV using a data sample corresponding to an integrated luminosity of 6.8 fb(-1). The transverse polarization asymmetry A(T)(2) and the time-reversal-odd charge-and-parity asymmetry A(im) are measured for the first time, together with the K* longitudinal polarization fraction F(L) and the muon forward-backward asymmetry A(FB) for the decays B(0)→K(*0)μ(+)μ(-) and B(+)→K(*+)μ(+)μ(-). The B→K*μ(+)μ(-) forward-backward asymmetry in the most sensitive kinematic regime, 1≤q(2)<6 GeV(2)/c(2), is measured to be A(FB)=0.29(-0.23)(+0.20)(stat)±0.07(syst), the most precise result to date. No deviations from the standard model predictions are observed.

Search for a Higgs boson in the diphoton final state in pp collisions at sqrt[s]=1.96 TeV

A search for a narrow Higgs boson resonance in the diphoton mass spectrum is presented based on data corresponding to 7.0  fb{-1} of integrated luminosity from pp collisions at sqrt[s]=1.96  TeV collected by the CDF experiment. No evidence of such a resonance is observed, and upper limits are set on the cross section times branching ratio of the resonant state as a function of Higgs boson mass. The limits are interpreted in the context of the standard model and one fermiophobic benchmark model where the data exclude fermiophobic Higgs bosons with masses below 114  GeV/c{2} at a 95% Bayesian credibility level.

Measurement of the B(s)0 lifetime in fully and partially reconstructed B(s)0→D(s)(-)(ϕπ(-))X decays in p¯p collisions at √s=1.96 TeV

We present a measurement of the B(s)(0) lifetime in fully and partially reconstructed B(s)(0)→D(s)(-)(ϕπ(-))X decays in 1.3  fb(-1) collected in pp ¯ collisions at √s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. We measure τ(B(s)(0))=1.518±0.041(stat)±0.027(syst)  ps. The ratio of this result and the world average B(0) lifetime yields τ(B(s)(0))/τ(B(0))=0.99±0.03, which is in agreement with recent theoretical predictions.

Measurement of polarization and search for CP violation in B(s)0→φφ decays

We present the first measurement of polarization and CP-violating asymmetries in a B(s)(0) decay into two light vector mesons, B(s)(0)→φφ, and an improved determination of its branching ratio using 295 decays reconstructed in a data sample corresponding to 2.9 fb(-1) of integrated luminosity collected by the CDF experiment at the Fermilab Tevatron collider. The fraction of longitudinal polarization is determined to be f(L)=0.348±0.041(stat)±0.021(syst), and the branching ratio B(B(s)(0)→φφ)=[2.32±0.18(stat)±0.82(syst)]×10(-5). Asymmetries of decay angle distributions sensitive to CP violation are measured to be A(u)=-0.007±0.064(stat)±0.018(syst) and A(v)=-0.120±0.064(stat)±0.016(syst).

Search for a heavy toplike quark in pp collisions at √s=1.96 TeV

We present the results of a search for pair production of a heavy toplike (t') quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6 fb(-1) collected by the CDF II detector in pp collisions at √s=1.96 TeV. We perform parallel searches for t'→Wb and t'→Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t' quark mass, we set upper limits on the t't' production cross section and exclude a standard model fourth-generation t' quark decaying to Wb (Wq) with mass below 358 (340) GeV/c(2) at 95% C.L.

Top-quark mass measurement using events with missing transverse energy and jets at CDF

We present a measurement of the top-quark mass using a sample of t ̄t events in 5.7 fb(-1) of integrated luminosity from p ̄p collisions at the Fermilab Tevatron with √s=1.96 TeV and collected by the CDF II Detector. We select events having large missing transverse energy, and four, five, or six jets with at least one jet tagged as coming from a b quark, and reject events with identified charged leptons. This analysis considers events from the semileptonic t ̄t decay channel, including events that contain tau leptons. The measurement is based on a multidimensional template method. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of M(top)=172.32±2.4(stat)±1.0(syst)  GeV/c(2).