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Study of the tau- ---> pi- pi- pi+ pi0 pi0 nu/tau and tau- --> 3h- 2h+ nu/tau Decays Using the BaBar Detector

Description: The {tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{pi}{sup 0}{pi}{sup 0}{nu}{sub {tau}} and {tau}{sup -} {yields} 3h{sup -} 2h{sup +} {nu}{sub {tau}} decays have been studied using the BABAR experiment at the PEP-II e{sup +}e{sup -} storage ring. Preliminary branching fractions are given for the {tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{pi}{sup 0}{pi}{sup 0}{nu}{sub {tau}} and to the sub-channels {tau}{sup -} {yields} {eta}{pi}{sup -} {pi}{sup 0}{nu}{sub {tau}} and {tau}{sup -} {yields} {omega}(782){pi}{sup -}{pi}{sup 0}{nu}{sub {tau}}. A preliminary upper limit is given on the branching fraction for the {phi}(1020){pi}{sup -}{pi}{sup 0}{nu}{sub {tau}} mode. In addition a preliminary measurement of the branching fraction of the {tau}{sup -} {yields} 3h{sup -}2h{sup +} {nu}{sub {tau}} decay (h = {pi}, K) is presented.
Date: June 21, 2005
Creator: Sobie, R. & U., /Victoria
Partner: UNT Libraries Government Documents Department

Measurement of the Tau Lepton Lifetime with BaBar

Description: The mean lifetime of the tau lepton is measured from the decay length distribution of 3-prong tau decays from e{sup +}e{sup -} collisions at the {Upsilon}(4S) resonance. A data sample of 80.0 fb{sup -1} collected with the BABAR detector at the PEP-II B Factory is used for this measurement. The measured tau lifetime is: {tau}{sub {tau}} = 289.40 {+-} 0.91 (stat.) {+-} 0.90 (syst.) fs. All the results are preliminary.
Date: June 27, 2005
Creator: Lusiani, A. & /Pisa, Scuola Normale Superiore /INFN, Pisa
Partner: UNT Libraries Government Documents Department

Measurement of the branching fraction for $\tau\to\eta K\nu_\tau$ and a search for second-class currents in $\tau\to\eta\pi\nu_\tau$ with $\eta\to\pi^ \pi^-\pi0$

Description: The authors report on analyses of tau lepton decays {tau}{sup -} {yields} {eta}K{sup -}{nu}{sub {tau}} and {tau}{sup -} {yields} {eta}{pi}{sup -}{nu}{sub {tau}}, with {eta} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup 0}, using 470 fb{sup -1} of data from the BABAR experiment at PEP-II, collected at center-of-mass energies at and near the {Upsilon}(4S) resonance. They measure the branching fraction for the {tau}{sup -} {yields} {eta}K{sup -}{nu}{sub {tau}} decay mode, {Beta}({tau}{sup -} {yields} {eta}K{sup -}{nu}{sub {tau}}) = (1.42 {+-} 0.11(stat) {+-} 0.07(syst)) x 10{sup -4}, and report a 95% confidence level upper limit for the second-class current process {tau}{sup -} {yields} {eta}{pi}{sup -}{nu}{sub {tau}}, {Beta}({tau}{sup -} {yields} {eta}{pi}{sup -}{nu}{sub {tau}}) < 9.9 x 10{sup -5}.
Date: August 12, 2011
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP et al.
Partner: UNT Libraries Government Documents Department

Studies of sigma(e+ e- to hadrons) at BaBar using Initial State Radiation (ISR)

Description: We present a review of BaBar results on e{sup +}e{sup -} {yields} hadrons using the initial state radiation technique. Cross sections over the {radical}s range from threshold to 4-5 GeV, with very small point-to-point systematic errors, are presented for the {pi}{sup +}{pi}{sup -}{pi}{sup 0}, 2({pi}{sup +}{pi}{sup -}), 2(K{sup +}K{sup -}), 3({pi}{sup +}{pi}{sup -}), 2({pi}{sup +}{pi}{sup -})2{pi}{sup 0}, 2({pi}{sup +}{pi}{sup -})K{sup +}K{sup -}, and p{bar p} final states. The preliminary results of e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup +}{pi}{sup -} and e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup 0}{pi}{sup 0} cross sections are also presented.
Date: October 24, 2007
Creator: Wang, W.F. & /Orsay, LAL
Partner: UNT Libraries Government Documents Department

Study of the Tau- to Pi- Pi+ Pi- Pi0 Nu/Tau And Tau- to Pi- Pi- Pi+ Eta Nu/Tau Decays Using the BaBar Detector

Description: The {tau}{sup -} {yields} {pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} and {tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{eta}{nu}{sub {tau}} decays have been studied with the BABAR detector. Preliminary branching fractions on the two modes are presented. The {tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{eta}{nu}{sub {tau}} mode is found to have a large contribution from the {tau}{sup -} {yields} {omega}{pi}{sup -}{nu}{sub {tau}} decay. The {tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{eta}{nu}{sub {tau}} decay is studied using the {eta} {yields} {gamma}{gamma} mode and the {tau}{sup -} f{sub 1}(1285){pi}{sup -}{nu}{sub {tau}} decay is seen to be the primary source of these decays. A 90% confidence level upper limit is placed on the {tau}{sup -} {yields} {eta}{prime}(958){pi}{sup -}{nu}{sub {tau}} decay which proceeds through a second-class current and is expected to be forbidden in the limit of perfect isospin symmetry.
Date: November 14, 2007
Creator: Sobie, Randall & U., /Victoria
Partner: UNT Libraries Government Documents Department

Search for tau- ---> 4pi- 3pi+ (pi0) nu/tau Decays

Description: A search for the decay of the {tau} lepton to seven charged pions and at most one {pi}{sup 0} was performed using the BABAR detector at the PEP-II e{sup +}e{sup -} collider. The analysis uses data recorded on and near the {Upsilon}(4S) resonance between 1999 and 2003, a total of 124.3 fb{sup -1}. They observe 7 events with an expected background of 11.9 {+-} 2.2 events and calculate a preliminary upper limit of BR({tau}{sup -} {yields} 4{pi}{sup -} 3{pi}{sup +}({pi}{sup 0}){nu}{sub {tau}}) < 2.7 x 10{sup -7} at 90% CL. This is a significant improvement over the previous limit established by the CLEO Collaboration.
Date: June 21, 2005
Creator: Ter-Antonian, R.; Kass, R.; Allmendinger, T.; U., /Ohio State; Hast, C. & /SLAC
Partner: UNT Libraries Government Documents Department

Search for Lepton-Flavor and Lepton-Number Violation in the Decay tau to lhh'

Description: A search for lepton-flavor and lepton-number violation in the decay of the tau lepton into one charged lepton and two charged hadrons is performed using 221.4 fb{sup -1} of data collected at an e{sup +}e{sup -} center-of-mass energy of 10.58 GeV with the BABAR detector at the PEP-II storage ring. In all 14 decay modes considered, the observed data are compatible with background expectations, and upper limits are set in the range {Beta}({tau} {yields} {ell}hh') < (0.7-4.8) x 10{sup -7} at 90% confidence level.
Date: June 29, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department

The Search for B+ to Tau+ Nu(Tau) at BaBar

Description: We present a search for the decay B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}} using 288 fb{sup -1} of data collected at the {Upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed semileptonic B decay (B{sup -} {yields} D{sup o}{ell}{sup -}{bar {nu}}{sub {ell}}X) is selected, and in the recoil a search for B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}} signal is performed. The {tau} is identified in the following channels: {tau}{sup +} {yields} e{sup +}{nu}{sub e}{bar {nu}}{sub {tau}}, {tau}{sup +} {yields} {mu}{sup +} {nu}{sub {mu}}{bar {nu}}{sub {tau}}, {tau}{sup +} {yields} {pi}{sup +}{pi}{sup 0}{bar {nu}}{sub {tau}}. We measure a branching fraction of {Beta}(B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}}) = 0.88{sub -0.67}{sup +0.68}(stat.) {+-} 0.11(syst.) x 10{sup -4} and extract an upper limit on the branching fraction, at the 90% confidence level, of {Beta}(B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}}) < 1.8 x 10{sup -4}. We calculate the product of the B meson decay constant and |V{sub ub}| to be f{sub B} {center_dot} |V{sub ub}| = (7.0{sub -3.6}{sup +2.3}(stat.){sub -0.5}{sup +0.4}(syst.)) x 10{sup -4} GeV.
Date: January 8, 2007
Creator: Corwin, L.A.
Partner: UNT Libraries Government Documents Department

Evidence for B+ --> tau+ nu_tau Decays using Hadronic B Tags

Description: We present a search for the decay B{sup +} --> {tau}{sup +} {nu}{sub {tau}} using 467.8 x 10{sup 6} B{anti B} pairs collected at the {Upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. We select a sample of events with on completely reconstructed B{sup -} in an hadronic decay mode (B{sup -} --> D{sup (*)0}X{sup -} and B{sup -} --> J/{psi} X{sup -}). We examine the rest of the event to search for a B{sup +} --> {tau}{sup +} {nu}{sub {tau}} decay. We identify the {tau}{sup +} lepton in the following modes: {tau}{sup +} --> e{sup +} {nu}{sub e}{anti {nu}}{sub {tau}}, {tau}{sup +} --> {mu}{sup +} {nu}{sub {mu}}{anti {nu}}{sub {tau}}, {tau}{sup +} --> {pi}{sup +}{anti {nu}}{sub {tau}} and {tau}{sup +} --> {rho}{anti {nu}}{sub {tau}}. We find an excess of events with respect to expected background, which excludes the null signal hypothesis at the level of 3.3 {sigma} and can be converted to a branching fraction central value of B(B{sup +} --> {tau}{sup +} {nu}{sub {tau}})= (1.80{sup + 0.57}{sub - 0.54}(stat.) {+-} 0.26 (syst.)) x 10{sup -4}.
Date: August 11, 2011
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP et al.
Partner: UNT Libraries Government Documents Department

Study of Exclusive Semileptonic B Meson Decays toTau Leptons

Description: We present the results of a search for four exclusive semileptonic decays B {yields} D{sup (*)}{tau}{sup -}{bar {nu}}{sub {tau}} in 209 fb{sup -1} of data collected with the BABAR detector, corresponding to 232 million e+e- {yields} {Upsilon}(4S) {yields} B{bar B} events. We select events with a D{sup (*)} meson and a light lepton (e or {mu}) recoiling against a fully-reconstructed B meson. We perform a fit to the lepton spectrum and missing mass squared to discriminate signal events from backgrounds, predominantly B {yields} D{sup (*)}{tau}{sup -}{bar {nu}}{sub {tau}}. A control sample of identified D**{ell}{sup -}{bar {nu}}{sub {ell}} events is included in the fit to estimate the background contribution from these decays. We measure {beta}(B {yields} D{sub {tau}{nu}}) = (0.86{+-}0.24{+-}0.11{+-}0.06)% and {beta}(B {yields} D*{sub {tau}{nu}}) = (1.62{+-}0.31{+-}0.10{+-}0.05)%, where the errors are statistical, systematic, and normalization-mode related, respectively, and where the results are expressed for the {bar B}{sup 0} lifetime.
Date: October 15, 2007
Creator: Mazur, Michael A. & /SLAC /UC, Santa Barbara
Partner: UNT Libraries Government Documents Department

Search for CP Violation in the Decay tau- \to pi- K^0_S (>= 0 pi0) nu_tau

Description: We report a search for CP violation in the decay {tau}{sup -} {yields} {pi}{sup -}K{sub S}{sup 0}({>=} 0{pi}{sup 0}){nu}{sub {tau}} using a dataset of 437 million {tau} lepton pairs, corresponding to an integrated luminosity of 476 fb{sup -1}, collected with the BABAR detector at the PEP-II asymmetric energy e{sup +}e{sup -} storage rings. The CP-violating decay-rate asymmetry is determined to be (-0.45 {+-} 0.24 {+-} 0.11)%, approximately three standard deviations from the Standard Model prediction of (0.33 {+-} 0.01)%.
Date: February 16, 2012
Creator: Lees, J.P.; Poireau, V.; Tisserand, V.; /Annecy, LAPP; Garra Tico, J.; Grauges, E. et al.
Partner: UNT Libraries Government Documents Department

Measurements of Charged Current Lepton Universality and |Vus| using Tau Lepton Decays to e- v v, __- v v, pi- v and K- v

Description: Using 467 fb{sup -1} of e{sup +}e{sup -} annihilation data collected with the BABAR detector, they measure {Beta}({tau}{sup -} {yields} {mu}{sup -}{bar {nu}}{sub {mu}}{nu}{sub {tau}})/{Beta}({tau}{sup -} {yields} e{sup -} {bar {nu}}{sub e}{nu}{sub {tau}}) = (0.9796 {+-} 0.0016 {+-} 0.0036), {Beta}({tau}{sup -} {yields} {pi}{sup -} {nu}{sub {tau}})/{Beta}({tau}{sup -} {yields} e{sup -}{bar {nu}}{sub e}{nu}{sub {tau}}) = (0.5945 {+-} 0.0014 {+-} 0.0061), and {Beta}({tau}{sup -} {yields} K{sup -}{nu}{sub {tau}})/{Beta}({tau}{sup -} {yields} e{sup -}{bar {nu}}{sub e}{nu}{sub {tau}}) = (0.03882 {+-} 0.00032 {+-} 0.00057), where the uncertainties are statistical and systematic, respectively. From these precision {tau} measurements, they test the Standard Model assumption of {mu}-e and {tau}-{mu} charge current lepton universality and provide determinations of |V{sub us}| experimentally independent of the decay of a kaon.
Date: June 30, 2011
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

A Search for the Decay B+ ---> Tau+ Nu/Tau at BaBar

Description: Based on an 87-fb{sup -1} dataset collected by the Babar detector at the PEP-II asymmetric-energy B-Factory, a search for D{sup 0}-{bar D}{sup 0} mixing has been made using the semileptonic decay modes D*{sup +} {yields} {pi}{sup +}D{sup 0}, D{sup 0} {yields} Ke{nu} (+c.c.). The use of these modes allows unambiguous flavor tagging and a combined fit of the D{sup 0} decay time and D*{sup +}-D{sup 0} mass difference ({Delta}M) distributions. The high-statistics sample of unmixed semileptonic D{sup 0} decays is used to model the {Delta}M distribution and time-dependence of mixed events directly from the data. Neural networks are used to select events and reconstruct the D{sup 0}. A result consistent with no charm mixing has been obtained, R{sub mix} = 0.0023 {+-} 0.0012 {+-} 0.0004. This corresponds to an upper limit of R{sub mix} < 0.0042 (90% CL).
Date: November 2, 2005
Creator: Datta, M.
Partner: UNT Libraries Government Documents Department

Precision Measurements of Tau Lepton Decays

Description: Using data collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV, the branching fractions {Beta}({tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}) = (8.83 {+-} 0.01 {+-} 0.13)%, {Beta}({tau}{sup -} {yields} K{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}) = (0.273 {+-} 0.002 {+-} 0.009)%, {Beta}({tau}{sup -} {yields} K{sup -}{pi}{sup -}K{sup +}{nu}{sub {tau}}) = (0.1346 {+-} 0.0010 {+-} 0.0036)%, and {Beta}({tau}{sup -} {yields} K{sup -}K{sup -}K{sup +}{nu}{sub {tau}}) = (1.58 {+-} 0.13 {+-} 0.12) x 10{sup -5} are measured where the uncertainties are statistical and systematic, respectively. The invariant mass distribution for the {tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}} {yields} K{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}, {tau}{sup -} {yields} K{sup -}{pi}{sup -}K{sup +}{nu}{sub {tau}} and {tau}{sup -} {yields} K{sup -}K{sup -}K{sup +}{nu}{sub {tau}} decays are unfolded to correct for detector effects. A measurement of {Beta}({tau}{sup -} {yields} {phi}{pi}{sup -}{nu}{sub {tau}}) = (3.42 {+-} 0.55 {+-} 0.25) x 10{sup -5}, a measurement of {Beta}({tau}{sup -} {yields} {phi}K{sup -}{nu}{sub {tau}}) = (3.39 {+-} 0.20 {+-} 0.28) x 10{sup -5} and an upper limit on {Beta}({tau}{sup -} {yields} K{sup -}K{sup -}K{sup +}{nu}{sub {tau}}[ex.{phi}]) {le} 2.5 x 10{sup -6} {at} 905 CL are determined from a binned maximum likelihood fit of the {tau}{sup -} {yields} K{sup -}{pi}{sup -}K{sup +}{nu}{sub {tau}} and {tau}{sup -} {yields} K{sup -}K{sup -}K{sup +}{nu}{sub {tau}} K{sup +}K{sup -} invariant mass distributions. The branching ratio {Beta}({tau}{sup -} {yields} K{sup -}{nu}{sub {tau}})/{Beta}({tau}{sup -} {yields} {pi}{sup -}{nu}{sub {tau}}) is measured to be (6.531 {+-} 0.056 {+-} 0.093) x 10{sup -2} from which |V{sub us}| is determined to be 0.2255 {+-} 0.0023. The branching ratio {Beta}/({tau}{sup -} {yields} {mu}{nu}{sub {tau}}{bar {nu}}{sub {mu}})/{Beta}({tau}{sup -} {yields} e{sup -} {nu}{sub {tau}}{bar {nu}}{sub e}) = (9.796 {+-} 0.016 {+-} 0.035) x 10{sup -1} is measured enabling a precision test ...
Date: March 16, 2010
Creator: Nugent, Ian M. & U., /Victoria
Partner: UNT Libraries Government Documents Department

Tau Trigger at the ATLAS Experiment

Description: Many theoretical models, like the Standard Model or SUSY at large tan({beta}), predict Higgs bosons or new particles which decay more abundantly to final states including tau leptons than to other leptons. At the energy scale of the LHC, the identification of tau leptons, in particular in the hadronic decay mode, will be a challenging task due to an overwhelming QCD background which gives rise to jets of particles that can be hard to distinguish from hadronic tau decays. Equipped with excellent tracking and calorimetry, the ATLAS experiment has developed tau identification tools capable of working at the trigger level. This contribution presents tau trigger algorithms which exploit the main features of hadronic tau decays and describes the current tau trigger commissioning activities. Many of the SM processes being investigated at ATLAS, as well as numerous BSM searches, contain tau leptons in their final states. Being able to trigger effectively on the tau leptons in these events will contribute to the success of the ATLAS experiment. The tau trigger algorithms and monitoring infrastructure are ready for the first data, and are being tested with the data collected with cosmic muons. The development of efficiency measurements methods using QCD and Z {yields} {tau}{tau} events is well advanced.
Date: November 9, 2011
Creator: Benslama, K.; Kalinowski, A.; U., /Regina; Belanger-Champange, C.; Brenner, R.; U., /Uppsala et al.
Partner: UNT Libraries Government Documents Department

Hot Topics in BaBar

Description: The authors present recent results concerning the searches for light Higgs-like particles in the decay {Upsilon}(3S) {yields} {gamma}A{sup 0},A{sup 0} {yields} {mu}{sup +}{mu}{sup -} as well as for the lepton flavor violation in the decays {Upsilon}(3S) {yields} e{sup {+-}}{tau}{sup {-+}}, {mu}{sup {+-}}{tau}{sup {-+}} and {tau} {yields} 3l (l = e, {mu}) with the BABAR experiment.
Date: June 11, 2010
Creator: da Costa, Joao Firmino; /Orsay, LAL & ,
Partner: UNT Libraries Government Documents Department