t procedure, which has been elaborated by the Tau Physics Group within the Heavy Flavour Averaging Group (HFLAV) [1]. For EM-only decay, the branching ratio would be 50% and 50%. 1. Recent results on hadronic decays of tau from BaBar are reviewed. The branching fraction is measured to be (2.85 +/- 0.56 +/- 0.51) x 10(-4). This result is combined with other measurements to test e-mu and mu-tau universality in charged . . In the decay of both the muon and the tau, a virtual charged intermediate vector boson . More than 90% of these decays are via eight decay modes (Fig. Hadronic decays of tau lepton (at . Symbolically, this process can be expressed by the following differential equation, where N is the quantity and (lambda) is a positive rate called . Abstract The T lifetime has been measured at LEP to be T, = 294.6 3. Academia.edu uses cookies to personalize content, tailor ads and improve the user experience. Exotic atoms 3 A study of the muon decay channel of the r lepton with the presence of a pho- . Extensive systematic studies are performed, in order to match the large statistics of the data sample corresponding to over 300 000 measured and identified decays. In the following, we use "branching fraction" to refer to the partial decay fraction of a particle like the into a specic decay mode, and "branching ratio" to refer to quantities How can I obtain the branching ratios for the tau decay from the CKM ignoring phase space and form factor and please suggest a numerical example if possible? The corresponding spectral function for the decay v is given by: (2) Equation 1 and 2 gives: (3) The muonic tau decay width for pion is given by: (4) Equation 3 and 4 reduces to: (5) Therefore, the branching fraction of the pionic tau decay is determined by the pion and tau life times ( and ): The branching fraction of a certain decay is simply defined as: where is the total width of the particle A. Jan 9, 2015. Use this to calculate the ratio of following decays: ( e e ) ( e ) How does this relate to the lifetime of the tau lepton? The tau is the only lepton that can decay into hadrons - the other leptons do not have the necessary mass. U.S. Department of Energy Office of Scientific and Technical Information. Enter the email address you signed up with and we'll email you a reset link. Measurement of the branching ratio for the decay tau --->e- nu -bare nu tau. 2008 Apr 25;100(16):161801. doi: 10.1103/PhysRevLett.100.161801. This discrepancy _ 'is derived from about 60 different measurements of branching fractions and some . (The lifetime of the muon is given in Q4, and the masses of the tau and muon are on the particle handout.) In total 33073 tau->e nue nutau candidates were identified from a sample of 186197 selected tau decays, giving a branching ratio of 17.81 +- 0.09(stat) +_ 0.06(sys)%. The measured leptonic branching fractions correspond to a tau lifetime of (3.0 +- 0.2) x 10/sup -13/ s. Secondly, the total branching fraction to one charged hadron plus at least one neutral particle is measured to be (7 +- 3)% higher than the branching fraction expected from a combination of previous measurements and theoretical predictions. In the following, we use "branching fraction" to refer to the partial decay fraction of a particle like the into a specic decay mode, and "branching ratio" to refer to quantities The only energy scale for muon or tau decay is the mass of the decaying lepton (m in Q4; m in Q5). D. S. Akerib, B. Barish, M. Chadha, D. F. Cowen, G. Eigen, J. S. Miller, J. Urheim, A. J. Weinstein, D. Acosta, G. Masek, B. Ong, H. Paar, M. Sivertz, A. Bean, J . Since tau muons are too heavy, only e+/e- and mu+/mu- pairs are produced at 50% branching ratio. A complete and consistent set of tau hadronic branching ratios is presented for 18 exclusive modes. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN-PPE/95-140 September 12, 1995 Tau hadronic branching ratios The ALEPH Collaborationu0003 Abstract From 64492 selected u001c -pair events, produced at the Z 0 resonance, the measurement of the tau decays into hadrons from a global analysis using 1991, 1992 and 1993 ALEPH data is presented. A detailed study of the systematics entering the$\pi^0$ reconstruction is also given. A particular emphasis of the Workshop was a detailed examination of the '1-prong problem': the discrepancy between the inclusive measurement of one-charged-particle decay branching ratio and . Charlton PPE Division, CERN, 1211 Geneva 23, Switzerland. 9. At present, the decay modes of the tau lepton containing l-charged particle are not completely understood. More than 12%, as a correct solution for (a) will show. In total 33073 tau->e nue nutau candidates were identified from a sample of 186197 selected tau decays, giving a branching ratio of 17.81 +- 0.09(stat) +_ 0.06(sys)%. In the absence of a signal, we set the limit on the branching ratio B . Epub 2008 Apr 21. There are more decay modes that can happen via the electromagnetic interaction. The branching ratio for the decay tau->e nue nutau has been measured using Z0 decay data collected by the OPAL experiment at LEP. Included in this study is the first direct measurement of radiative tau decay. B. Aubert, R. Barate, D. Boutigny, F. Couderc, J. M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, V. Tisserand, A. Zghiche, A. Palano, A. Pompili, J. C. Chen, N . Measurement of the absolute branching fraction of Ds+ --> tau+ nutau decay Phys Rev Lett. #3. The branching ratio for the decay tau->e nue nutau has been measured using Z0 decay data collected by the OPAL experiment at LEP. The branching fraction of {tau}{sup -} {yields} 3h{sup -} 2h{sup +}{nu}{sub {tau}} is measured to be (8.56 {+-} 0.05{sub stat} {+-} 0.42{sub sys}) x 10{sup -4}. B. Niczyporuk, T. Zeudziewicz, K. W. Chen, R. Hartung, H. Vogel, H. Wegener, J. K. Bienlein, R. Graumann, J. Krger, M. Leissner, C. Rippich, M. Schmitz, E. Filos . . Thus, the total The measured leptonic branching fractions correspond to a tau lifetime of (3.0 zt 0.2) x 10 -13 s which is slightly longer than the average measured tau lifetime of (2.8 rt 0.2) x IO-l3 s. The one- and three-charged-particle inclusive branching ratios of the tau decay are measured to be B/sub 1/ = (84.7 +- 1.0)% and B/sub 3/ = (15.1 +- 1.0)%, where B/sub 1/+B/sub 3/ is constrained to be 99.85%. This plot shows decay for decay constant () of 25, 5, 1, 1/5, and 1/25 for x from 0 to 5. We find the ratio of the measured r + pyv~ branching fraction to the expected value from QED to be 1.03 f 0.44. At present, the decay modes of the tau lepton containing l-charged particle are not completely understood. For the decay of the muon, ee , the same formula applies, with the muon mass and coupling, m and g , replacing those of the tau. The underlaying substructure of this decay exposes strong contribution from {rho} resonance. Thus the. Search terms: Advanced search options. The similarity of values of the two branching ratios is a consequence of lepton universality. the muon and the tau decay via the weak interaction as shown in Figure 1.1. Submitted to Physical Review Letters . By using our site, you agree to our collection of information through the use of cookies. Like the other decay modes of the tau, the hadronic decay is through the weak interaction.. discrepancy between the inclusive branching fraction and the sum of the exclusive branching fractions to final states containing one charged particle. . The branching fractions of the dominant hadronic tau decays are:. 1990 Mar 1;41(5):1414-1424. The U.S. Department of Energy's Office of Scientific and Technical Information 58. Phys Rev D Part Fields. decays to a K in place of a are restricted by Cabibbo suppression (that is a small off-diagonal element of the CKM matrix will enter into the calculation of this tree level diagram) . 470. For EM-only decay, the branching ratio would be 50% and 50%. Its purpose is to gather the experts on tau lepton physics to examine the current understanding of the tau lepton physics and to assess future prospects. The comparison of the tau lifetime and leptonic branching fractions with the muon lifetime gives a direct measurement of the ratios g /ge and g /g . The decay vertex reconstruction method Background 0.5 0.6 I .o Tracking Resolution 0.5 2.6 1.o Decays of the tau with three charged particles in Alignment 0.4 0.5 1.o the final state have been used to measure the lifetime Branching Ratios/Polarisation 0.3 0.7 I.0 Particle Misidentification 0.1 by reconstructing the secondary vertex and . Branching fractions from the constrained t are derived from a set of basis modes. A quantity is subject to exponential decay if it decreases at a rate proportional to its current value. Most. Measurement of the branching ratio for the decay tau --->e- nu -bare nu tau. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): In the measured decay properties of the tau there is a discrepancy between the total branching fraction for the one charged particle decay modes and the sum of the branching fractions for the known individual modes. What's the branching ratio if it's only EM decay? [1-4] By definition, the total branching fraction for those modes, B,, is the sum of the separate branching fractions, B,, for the . The third column of branching ratios listed in Table 3 are the results of this . In recent years, B-s -> tau(+)tau(-) rare decay has attracted a lot of attention since it is very sensitive to the structure of standard model (SM) and potential source of new physics beyond SM. branching ratio, BL. branching ratio, BL. This result is combined with other measurements to test e-mu and mu-tau universality in charged . Enter the email address you signed up with and we'll email you a reset link. . We have searched for resonance substructure in the decay. The branching fractions of the common purely leptonic tau decays are: 17.82% for decay into a tau neutrino, electron and electron antineutrino; 17.39% for decay into a tau neutrino, muon, and muon antineutrino. The estimate is based on a vector and scalar meson dominance parametrization of the relevant form factors, that explicitly accounts for pi^0-eta-eta' mixing. unscientific said: Strong interaction is more likely to occur, since only 12% of total reaction can be attributed to EM interaction. Abstract: We present an assessment of the standard model expectations for the branching ratio of the isotopic spin and G-parity violating decay tau --> eta' pi nu_tau.