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CP violation and suppressed $B_s$ decays at CDF

Description: The study of heavy-quark decays continues to have wide interest as a possible avenue for the discovery of physics beyond the standard model. With data samples as large as 6 fb{sup -1}, the CDF collaboration is exploring new channels that will extend the reach of measurements in probing the CKM mechanism of CP violation. Several new measurements are presented.
Date: December 1, 2011
Creator: Lewis, J. D.
Partner: UNT Libraries Government Documents Department

Observation of the Semileptonic Decays B to D*taunu and Evidence for B to D tau nu

Description: We present measurements of the semileptonic decays B{sup -} {yields} D{sup 0}{tau}{sup -}{bar {nu}}{sub {tau}}, B{sup -} {yields} D{sup *0}{tau}{sup -}{bar {nu}}{sub {tau}}, B{sup -} {yields} D{sup +}{tau}{sup -}{bar {nu}}{sub {tau}}, and B{sup -} {yields} D{sup *+}{tau}{sup -}{bar {nu}}{sub {tau}}, which are potentially sensitive to non-Standard Model amplitudes, The data sample comprises 232 x 10{sup 6} {Upsilon}(4s) {yields} B{bar B} decays collected with the BABAR detector. From a combined fit to B{sup -} and {bar B}{sup 0} channels, we obtain the branching fractions {beta}(B {yields} D{sub {tau}}{sup -}{bar {nu}}{sub {tau}}) = (0:86 {+-} 0:24 {+-} 0:11 {+-} 0:06)% and {beta}(B {yields} D*{tau}{sup -}{bar {nu}}{sub {tau}}) = (1:62 {+-} 0:31 {+-} 0:10 {+-} 0:05)% (normalized for the {bar B}{sup 0}), , where the uncertainties are statistical, systematic, and normalization-mode-related.
Date: September 14, 2007
Creator: B., Aubert
Partner: UNT Libraries Government Documents Department

Direct CP, Lepton Flavor and Isospin Asymmetries in the Decays B->K(*)l+l-

Description: We measure rate asymmetries for the rare decays B {yields} K{sup (*)}{ell}{sup +}{ell}{sup -}, where {ell}{sup +}{ell}{sup -} is either e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -}, using a sample of 384 million B{bar B} events collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider. We find no evidence for direct CP or lepton-flavor asymmetries. For dilepton masses below the J/{psi} resonance, we find evidence for unexpectedly large isospin asymmetries in both B {yields} K{ell}{sup +}{ell}{sup -} and B {yields} K*{ell}{sup +}{ell}{sup -} which differ respectively by 3.2{sigma} and 2.7{sigma}, including systematic uncertainties, from the Standard Model expectations.
Date: March 3, 2009
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Diboson physics at CDF

Description: We have studied diboson events produced by p{bar p} collisions at {radical}s = 1.96 TeV using the CDF detector. Our observations of Z{gamma}, WZ, and ZZ production are consistent with Standard Model predictions, and we set limits on some anomalous couplings.
Date: July 1, 2008
Creator: Phillips, Thomas J.
Partner: UNT Libraries Government Documents Department

Measurement of the forward-backward charge asymmetry and extraction of $sin^2Theta^{eff}_W$ in $p\bar{p} \to Z/\gamma^{*}+X \to e^+e^-+X$ events produced at $\sqrt{s}=1.96$ TeV

Description: We present a measurement of the forward-backward charge asymmetry (A{sub FB}) in p{bar p} {yields} Z/{gamma}* + X {yields} e{sup +}e{sup -} + X events at a center-of-mass energy of 1.96 TeV using 1.1 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider. A{sub FB} is measured as a function of the invariant mass of the electron-positron pair, and found to be consistent with the standard model prediction. We use the A{sub FB} measurement to extract the effective weak mixing angle sin{sup 2} {theta}{sub W}{sup eff} = 0.2327 {+-} 0.0018 (stat.) {+-} 0.0006 (syst.).
Date: April 1, 2008
Creator: Abazov, V.M.; /Dubna, JINR; Abbott, B.; U., /Oklahoma; Abolins, M.; U., /Michigan State et al.
Partner: UNT Libraries Government Documents Department

Search for CP Violation in the Decays D0 to K- K+and D0 to pi- pi+

Description: We measure CP-violating asymmetries of neutral charmed mesons in the modes D{sup 0} {yields} K{sup -}K{sup +} and D{sup 0} {yields} {pi}{sup -}{pi}{sup +} with the highest precision to date by using D{sup 0} {yields} K{sup -}{pi}{sup +} decays to correct detector asymmetries. An analysis of 385.8 fb{sup -}1 of data collected with the BaBar detector yields values of a{sup KK}{sub CP} = (0.00 {+-} 0.34 (stat.) {+-} 0.13 (syst.))% and a{sup {pi}{pi}}{sub CP} = (-0.24 {+-} 0.52 (stat.) {+-} 0.22 (syst.))%, which agree with Standard Model predictions.
Date: September 24, 2007
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Karyotakis, Y.; Lees, J.P.; Poireau, V. et al.
Partner: UNT Libraries Government Documents Department

Study of direct CP violation in B+- ---> J/psi K+- (pi+-) file decays

Description: The authors present a search for direct CP violation in B{sup {+-}} {yields} J/{psi}K{sup {+-}}{pi}{sup {+-}} decays. The event sample is selected from 2.8 fb{sup -1} of p{bar p} collisions recorded by D0 experiment in Run II of the Fermilab Tevatron Collider. The charge asymmetry A{sub CP}(B{sup +} {yields} J/{psi}K{sup +}) = +0.0075 {+-} 0.0061(stat.) {+-} 0.0027(syst.) is obtained using a sample of approximately 40 thousand B{sup {+-}} {yields} J/{psi}K{sup {+-}} decays. The achieved precision is of the same level as the expected deviation predicted by some extensions of the standard model. They also measured the charge asymmetry A{sub CP}(B{sup +} {yields} J/{psi}{pi}{sup +}) = -0.09 {+-} 0.08(stat.){+-}0.03(syst.).
Date: February 1, 2008
Creator: Abazov, V.M.; /Dubna, JINR; Abbott, B.; U., /Oklahoma; Abolins, M.; U., /Michigan State et al.
Partner: UNT Libraries Government Documents Department

A Search for B -> tau nu Recoiling Against B- -> D0 l- nu X

Description: The authors present a search for the decay B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}} ({ell} = {tau}, {mu}, or e) in (458.9 {+-} 5.1) x 10{sup 6} B{bar B} pairs recorded with the BABAR detector at the PEP-II B-Factory. They search for these B decays in a sample of B{sup +}B{sup -} events where one B-meson is reconstructed as B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}X. Using the method of Feldman and Cousins, they obtain {Beta}(B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}}) = (1.7 {+-} 0.8 {+-} 0.2) x 10{sup -4}, which excludes zero at 2.3{sigma}. They interpret the central value in the context of the Standard Model and find the B meson decay constant to be f{sub B}{sup 2} = (62 {+-} 31) x 10{sup 3} MeV{sup 2}. They find no evidence for B{sup +} {yields} e{sup +}{nu}{sub e} and B{sup +} {yields} {mu}{sup +}{nu}{sub {mu}} and set upper limits at the 90% C.L. {Beta}(B{sup +} {yields} e{sup +}{nu}{sub e}) < 0.8 x 10{sup -5} and {Beta}(B{sup +} {yields} {mu}{sup +}{nu}{sub {mu}}) < 1.1 x 10{sup -5}.
Date: December 17, 2009
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Search for High-Mass Resonances Decaying into Leptons of Different Flavor (e mu, e tau, mu tau) in p anti-p Collisions at sqrt(s) = 1.96 TeV

Description: We present a search for high-mass resonances decaying into two leptons of different flavor: e{mu}, e{tau}, and {mu}{tau}. These resonances are predicted by several models beyond the standard model, such as the R-parity-violating MSSM. The search is based on 1 fb{sup -1} of data collected at the Collider Detector at Fermilab (CDF II) in proton anti-proton collisions. Our observations are consistent with the standard model expectations. The results are interpreted to set 95% C.L. upper limits on {sigma} x BR of {tilde {nu}}{sub {tau}} {yields} e{mu}, e{tau}, {mu}{tau}.
Date: October 1, 2008
Creator: Tu, Yanjun & U., /Pennsylvania
Partner: UNT Libraries Government Documents Department

Study of the k+ to pi+, neutrino, anti-neutrino decay in the momentum region p(pi+) < 199 MeV/C

Description: Experiment E949 at Brookhaven National Laboratory has observed three candidate events for the decay K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}} in the pion momentum region 140 &lt; P{sub {pi}} &lt; 199 MeV/c in a exposure of 1.71 x 10{sup 12} stopped kaons with an estimated total background of 0.93 {+-} 0.17(stat.){sub -0.24}{sup +0.32}(syst.) events. Combination of this observation with previous results, assuming a pion spectrum as predicted by the standard model, produces a branching fraction of {beta} = (1.73{sub -1.05}{sup +1.15}) x 10{sup -10}. We also give the interpretation of the combined results for alternative model of the decay K{sup +} {yields} {pi}{sup +} + nothing.
Date: January 1, 2009
Creator: Artamonov, A.V.; Bassalleck, B.; Bhuyan, B.; Blackmore, E.W.; Bryman, D.A.; Chen, S. et al.
Partner: UNT Libraries Government Documents Department

A Search for the Rare Decay B0 to tau+tau- atBaBar

Description: We present the results of a search for the decay B{sup 0} {yields} {tau}{sup +}{tau}{sup -} in a data sample of (232 {+-} 3) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays using the BABAR detector. Certain extensions of the Standard Model predict measurable levels of this otherwise rare decay. We reconstruct fully one neutral B meson and seek evidence for the signal decay in the rest of the event. We find no evidence for signal events and obtain {Beta}(B{sup 0} {yields} {tau}{sup +}{tau}{sup -}) &lt; 3.2 x 10{sup -3} at the 90% confidence level.
Date: November 9, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department

Measurement of Time-Dependent CP Asymmetries and the CP-Odd Fraction in the Decay B0->D*+D*-

Description: We present an updated measurement of time-dependent CP asymmetries and the CP-odd fraction in the decay B{sup 0} D*{sup +}D*{sup -} using 232 x 10{sup 6} B{bar B} pairs collected by the BABAR detector at the PEP-II B factory. We determine the CP-odd fraction to be 0.125 {+-} 0.044(stat) {+-} 0.007(syst). The time-dependent CP asymmetry parameters C{sub +} and S{sub +} are determined to be 0.06 {+-} 0.17(stat) {+-} 0.03(syst) and -0.75 {+-} 0.25(stat) {+-} 0.03(syst), respectively. The Standard Model predicts these parameters to be 0 and -sin2{beta}, respectively, in the absence of penguin amplitude contributions.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department

Search for signatures of extra dimensions in the diphoton mass spectrum at the Large Hadron Collider

Description: A search for signatures of extra dimensions in the diphoton invariant-mass spectrum has been performed with the CMS detector at the LHC. No excess of events above the standard model expectation is observed using a data sample collected in proton-proton collisions at {radical}s = 7 TeV corresponding to an integrated luminosity of 2.2 fb{sup -1}. In the context of the large-extra-dimensions model, lower limits are set on the effective Planck scale in the range of 2.3-3.8 TeV at the 95% confidence level. These limits are the most restrictive bounds on virtual-graviton exchange to date. The most restrictive lower limits to date are also set on the mass of the first graviton excitation in the Randall-Sundrum model in the range of 0.86-1.84 TeV, for values of the associated coupling parameter between 0.01 and 0.10.
Date: December 1, 2011
Creator: Chatrchyan, Serguei; Khachatryan, Vardan; Sirunyan, Albert M.; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas et al.
Partner: UNT Libraries Government Documents Department

Measurement of the K+ --> pi+ nu nu branching ratio

Description: Experiment E949 at Brookhaven National Laboratory studied the rare decay K{sup +}--&gt;pi{sup +} nu{ovr {nu}} and other processes with an exposure of 1.77 x 10{sup 12} k{sup +}'s. The data were analyzed using a blind analysis technique yielding one candidate event with an estimated background of 0.30 {+-} 0.03 events. Combining this result with the observation of two candidate events by the predecessor experiment E787 gave the branching ratio B(K{sup +}--&gt;pi{sup +} nu{ovr {nu}}) = (1.47{sub -0.89}{sup +1.30}) x 10{sup -10}, consistent with the standard model prediction of (0.74 {+-} 0.20) x 10{sup -10}. This is a more detailed report of results previously published [V.V. Anisimovsky et al., Phys. Rev. Lett. 93, 031801 (2004)].
Date: March 1, 2008
Creator: Adler, S.; Anisimovsky, V. V.; Aoki, M.; Ardebili, M.; Artamonov, A. V.; Atiya, M. et al.
Partner: UNT Libraries Government Documents Department

Search for associated Higgs boson production WH ---> WWW* ---> l+- nu l-prime+- nu-prime + X in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: The authors present a search for associated Higgs boson production in the process p{bar p} {yields} WH {yields} WWW* {yields} {ell}{sup {+-}}{nu} {ell}{prime}{sup {+-}} {nu}{prime} + X in final states containing two like-sign isolated electrons or muons (e{sup {+-}}e{sup {+-}}, e{sup {+-}} {mu}{sup {+-}}, or {mu}{sup {+-}} {mu}{sup {+-}}). The search is based on D0 Run II data samples corresponding to integrated luminosities of 360-380 pb{sup -1}. No excess is observed over the predicted standard model background. They set 95% C.L. upper limits on {sigma}(p{bar p} {yields} WH) x Br(H {yields} WW*) between 3.2 and 2.8 pb for Higgs masses from 115 to 175 GeV.
Date: July 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Non-susy exotics searches at the Tevatron

Description: The authors present results of searches for signs of physics beyond the Standard Model. The focus of this paper is on analyses not driven by SUSY models. Most of the presented results are based on {approx} 2 fb{sup -1} of data and obtained since summer of 2007. No significant excess of data over predicted background is observed. They report kinematic distributions, data and background counts, as well as limits on some parameters of selected models of new physics.
Date: May 1, 2008
Creator: Pronko, Alexandre
Partner: UNT Libraries Government Documents Department

Radiative b to d Penguins

Description: This article gives an overview of the recent searches and measurements of b {yields} d penguin transitions with the BaBar experiment. The branching fraction of these decays in the Standard Model (SM) is expected to be a factor of 10 or more lower than the corresponding b {yields} s penguin transitions, but a deviation from the SM prediction would be an equally striking sign of new physics. The exclusive decay B {yields} {pi}{ell}{ell} is searched by BaBar with no excess over the background found. The BaBar measurement of B {yields} ({rho}, {omega}){gamma} provides the first evidence of B{sup +} {yields} {rho}{sup +}{gamma}, {sup c} is in good agreement with the previous Belle results and provides a measurement of |V{sub td}/V{sub ts}| independent of the one from Bs mixing. No deviation from the SM is found.
Date: June 13, 2007
Creator: Bechtle, P.
Partner: UNT Libraries Government Documents Department

First Flavor-Tagged Determination of Bounds on Mixing-Induced CP Violation in B^0_s --> j/psi phi Decays

Description: This Letter describes the first determination 1 of bounds on the CP-violation parameter 2{beta}{sub s} using B{sub s}{sup 0} decays in which the flavor of the bottom meson at production is identified. The result is based on approximately 2, 000 B{sub s}{sup 0} {yields} J/{psi}{phi} decays reconstructed in a 1.35 fb{sup -1} data sample collected with the CDFII detector using p{bar p} collisions produced at the Fermilab Tevatron. We report confidence regions in the two-dimensional space of 2{beta}{sub s} and the decay-width difference {Delta}{Lambda}. Assuming the standard model predictions of 2{beta}{sub s} and {Delta}{Lambda}, the probability of a deviation as large as the level of the observed data is 15%, corresponding to 1.5 Gaussian standard deviations.
Date: December 1, 2007
Creator: CDF Collaboration
Partner: UNT Libraries Government Documents Department

Combined CDF and D0 upper limits on $gg\to H\to W^+W^-$ and constraints on the Higgs boson mass in fourth-generation fermion models with up to 8.2 fb$^{-1}$ of data

Description: We combine results from searches by the CDF and D0 Collaborations for a standard model Higgs boson (H) in the processes gg {yields} H {yields} W{sup +}W{sup -} and gg {yields} H {yields} ZZ in p{bar p} collisions at the Fermilab Tevatron Collider at {radical}s = 1.96 TeV. With 8.2 fb{sup -1} of integrated luminosity analyzed at CDF and 8.1 fb{sup -1} at D0, the 95% C.L. upper limit on {sigma}(gg {yields} H) x {Beta}(H {yields} W{sup +}W{sup -}) is 1.01 pb at m{sub H} = 120 GeV, 0.40 pb at m{sub H} = 165 GeV, and 0.47 pb at m{sub H} = 200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, we exclude at the 95% Confidence Level a standard-model-like Higgs boson with a mass between 124 and 286 GeV.
Date: August 1, 2011
Creator: Benjamin, Doug
Partner: UNT Libraries Government Documents Department

Combined upper limit on standard model higgs boson production at D0 in $p \bar{p}$ collisions at $\sqrt{s} = 1.96-TeV

Description: The latest searches for the Standard Model Higgs boson at a centre-of-mass energy of {radical}s = 1.96 TeV with the D0 and the CDF detectors at the Fermilab Tevatron collider are presented. For the first time since the LEP experiments the sensitivity for a Standard Model Higgs boson has been reached at a Higgs boson mass of 170 GeV/c{sup 2}.
Date: December 1, 2010
Creator: Bernhard, Ralf & U., /Freiburg
Partner: UNT Libraries Government Documents Department

Evidence for an anomalous like-sign dimuon charge asymmetry

Description: We present a measurement of the like-sign dimuon asymmetry in semileptonic b-hadron decays, performed using 6.1 fb{sup -1} of p{bar p} collisions recorded with the D0 detector at a center-of-mass energy {radical}s = 1.96 TeV at the Fermilab Tevatron collider. This measured value is A{sub sl}{sup b} = [-0.957 {+-} 0.251 (stat) {+-} 0.146 (syst)] %, which disagrees with the Standard Model prediction at a statistical level of 3.2 {sigma}, and provides the first evidence of anomalous CP violation in the mixing of neutral B mesons.
Date: January 1, 2011
Creator: Williams, M.R.J. & U., /Lancaster
Partner: UNT Libraries Government Documents Department

Search for $B_s \to \mu^+\mu^-$ and $B_d \to \mu^+\mu^-$ Decays with CDF II

Description: A search has been performed for B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and B{sup 0} {yields} {mu}{sup +}{mu}{sup -} decays using 7 fb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. The observed number of B{sup 0} candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of {Beta}(B{sup 0} {yields} {mu}{sup +}{mu}{sup -}) &lt; 6.0 x 10{sup -9} at 95% confidence level. We observe an excess of B{sub s}{sup 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{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} could produce such an excess or larger is 1.9%. These data are used to determine {Beta}(B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) = (1.8{sub -0.9}{sup +1.1}) x 10{sup -8} and provide an upper limit of {Beta}(B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) &lt; 4.0 x 10{sup -8} at 95% confidence level.
Date: July 1, 2011
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department