340 research outputs found

    The root of the universal tree and the origin of eukaryotes based on elongation factor phylogeny

    Get PDF
    The genes for the protein synthesis elongation factors Tu (EF-Tu) and G (EF-G) are the products of an ancient gene duplication, which appears to predate the divergence of all extant organismal lineages. Thus, it should be possible to root a universal phylogeny based on either protein using the second protein as an outgroup. This approach was originally taken independently with two separate gene duplication pairs, (i) the regulatory and catalytic subunits of the proton ATPases and (ii) the protein synthesis elongation factors EF-Tu and EF-G. Questions about the orthology of the ATPase genes have obscured the former results, and the elongation factor data have been criticized for inadequate taxonomic representation and alignment errors. We have expanded the latter analysis using a broad representation of taxa from all three domains of life. All phylogenetic methods used strongly place the root of the universal tree between two highly distinct groups, the archaeons/eukaryotes and the eubacteria. We also find that a combined data set of EF-Tu and EF-G sequences favors placement of the eukaryotes within the Archaea, as the sister group to the Crenarchaeota. This relationship is supported by bootstrap values of 60-89% with various distance and maximum likelihood methods, while unweighted parsimony gives 58% support for archaeal monophyly

    CP Measurement in Quantum Teleportation of Neutral Mesons

    Full text link
    Quantum teleportation using neutral pseudoscalar mesons shows novel connections between particle physics and quantum information. The projection basis, which is crucial in the teleportation process, is determined by the conservation laws of particle physics, and is different from the Bell basis, as in the usual case. Here we show that one can verify the teleportation process by CP measurement. This method significantly simplifies the high energy quantum teleportation protocol. Especially, it is rigorous, and is independent of whether CP is violated in weak decays. This method can also be applied to general verification of Einstein-Podolsky-Rosen correlations in particle physics.Comment: 7 page

    A Parton Model for Inclusive Semileptonic B Meson Decays

    Full text link
    The parton model for semileptonic B meson decays is studied with special attention to the decay distributions. We find that the spectra show dramatic variations when we introduce cuts on the hadronic energy or invariant mass of hadrons. Results for both b→ub\rightarrow u and b→cb\rightarrow c decays are presented. The detailed spectra may help to separate the two types of decays.Comment: 9 pages, DO-TH 93/29, OHSTPY-HEP-T-93-011, September 199

    CP Violation and Strong Phases from Penguins in B±→VV\bf B^{\pm}\rightarrow VV Decays

    Full text link
    We calculate direct CP-violating observables in charged B→VVB\to VV decays arising from the interference of amplitudes with different strong and CKM phases. The perturbative strong phases develop at order αs\alpha_s from absorptive parts of one-loop matrix elements of the next-to-leading logarithm corrected effective Hamiltonian. CPT constraints are maintained. Based on this model, we find that partial rate asymmetries between charge conjugate B±B^{\pm} decays can be as high as 15-30\% for certain channels with branching ratios in the 10−610^{-6} range. The small values of the coefficients of angular correlations, which we calculated previously to be of order 10−210^{-2}, are not significantly degraded by the strong phases. The charge asymmetries of rates and angular distributions would provide unambiguous evidence for direct CP violation.Comment: 24 pages, 3 figures (upon request), LaTeX, preprint DESY 93-19

    The Mass Definition in Hqet and a New Determination of Vcb_{\text{cb}}

    Full text link
    Positive powers of the mass parameter in a physical quantity calculated with the help of heavy quark effective theory originate from a Wilson coefficient in the matching of QCD and HQET Green function. We show that this mass parameter enters the calculation as a well--defined running current mass. We further argue that the recently found ill--definition of the pole mass, which is the natural expansion parameter of HQET, does not affect a phenomenological analysis which uses truncated perturbative series. We reanalyse inclusive semileptonic decays of heavy mesons and obtain the cc quark mass mcMS‟(mc)=(1.35±0.20) GeVm_c^{\overline{\text{MS}}}(m_c) = (1.35\pm 0.20)\,\text{GeV} where the error is almost entirely due to scale--uncertainties. We also obtain mbMS‟(mb)=(4.6±0.3) GeVm_b^{\overline{\text{MS}}}(m_b) = (4.6\pm 0.3)\,\text{GeV} and ∣Vcb∣(τB/1.49 ps)1/2=0.036±0.005|V_{cb}|(\tau_B/1.49\,\text{ps})^{1/2} = 0.036\pm 0.005 where the errors come from the uncertainty in the kinetic energy of the heavy quark inside the meson, in the experimental branching ratios, in QCD input parameters, and scale--uncertainties.Comment: 21 p., 5 figs, all style files incl., TUM-T31-56/R (Sec. 2 revised, phenomenological results unchanged

    Probing for the Charm Content of BB and ΄\Upsilon Mesons

    Full text link
    A slow J/ψJ/\psi bump exists in the inclusive B→J/ψ+XB\to J/\psi + X spectrum, while the softness of J/ψJ/\psi spectrum in ΄(1S)→J/ψ+X\Upsilon(1S) \to J/\psi + X decay is in strong contrast with expectations from color octet mechanism. We propose {\it intrinsic} charm as the explanation:the former is due to Bˉ→J/ψDπ\bar B\to J/\psi D \pi,with three charm quarks in the final state; the latter is just a small fraction of ΄(1S)→(ccˉ)slow+2\Upsilon(1S) \to (c\bar c)_{\rm slow} + 2"jet" events, where the slow moving ccˉc\bar c system evolves into D(∗)D^{(*)} pairs. Experimental search for these phenomena at B Factories and the Tevatron is strongly urged, as the implications go beyond QCD.Comment: 4 pages, REVTEX, 10 eps figures included. Major revision with more discussions on the rescattering background, and a reappraisal of the Upsilon(1S) decay in the presence of intrinsic charm, leading to a change in Titl

    A Phenomenological Analysis of Heavy Hadron Lifetimes

    Full text link
    A phenomenological analysis of lifetimes of bottom and charmed hadrons within the framework of the heavy quark expansion is performed. The baryon matrix element is evaluated using the bag model and the nonrelativistic quark model. We find that bottom-baryon lifetimes follow the pattern τ(Ωb)≃τ(Ξb−)>τ(Λb)≃τ(Ξb0)\tau(\Omega_b)\simeq\tau(\Xi_b^-)>\tau(\Lambda_b)\simeq\tau(\Xi_b^0). However, neither the lifetime ratio τ(Λb)/τ(Bd)\tau(\Lambda_b)/\tau( B_d) nor the absolute decay rates of the Λb\Lambda_b baryon and BB mesons can be explained. One way of solving both difficulties is to allow the presence of linear 1/mQ1/m_Q corrections by scaling the inclusive nonleptonic width with the fifth power of the hadron mass mHQm_{H_Q} rather than the heavy quark mass mQm_Q. The hierarchy of bottom baryon lifetimes is dramatically modified to τ(Λb)>τ(Ξb−)>τ(Ξb0)>τ(Ωb)\tau(\Lambda_b)>\tau(\Xi_b^-)>\tau(\Xi_b^0)>\tau( \Omega_b): The longest-lived Ωb\Omega_b among bottom baryons in the OPE prescription now becomes shortest-lived. The replacement of mQm_Q by mHQm_{H_Q} in nonleptonic widths is natural and justified in the PQCD-based factorization approach formulated in terms of hadron-level kinematics. For inclusive charmed baryon decays, we argue that since the heavy quark expansion does not converge, local duality cannot be tested in this case. We show that while the ansatz of substituting the heavy quark mass by the hadron mass provides a much better description of the charmed-baryon lifetime {\it ratios}, it appears unnatural and unpredictive for describing the {\it absolute} inclusive decay rates of charmed baryons, contrary to the bottom case.Comment: 35 pages, to appear in Phys. Rev. The CDF result on the lifetime ratio of Lambda_b and B_d is discusse

    Weak Phase Îł\gamma and Strong Phase ÎŽ\delta from CP Averaged B→ππB\to \pi\pi and πK\pi K Decays

    Full text link
    Assuming SU(3) symmetry for the strong phases in the four decay modes B\rarrow \pi^-\pi^+, \pi^0 \pi^+, \pi^- K^+, \pi^- \bar{K}^0 and ignoring the relative small electroweak penguin effects in those decays, the weak phase Îł\gamma and the strong phase ÎŽ\delta can be determined in a model independent way by the CP-averaged branching ratios of the four decay modes. It appears that the current experimental data for B→ππB\to \pi\pi and πK\pi K decays prefer a negative value of cos⁥γcos⁥Ύ\cos\gamma\cos\delta. By combining with the other constraints from VubV_{ub}, Bd,s0−Bˉd,s0B^{0}_{d,s}-\bar{B}^{0}_{d,s} mixings and indirect CP-violating parameter Ï”K\epsilon_K within the standard model, two favorable solutions for the phases Îł\gamma and ÎŽ\delta are found to lie in the region: 35^{\circ}\alt\gamma\alt 62^{\circ} and 106^{\circ}\alt \delta \alt 180^{\circ} or 86^{\circ}\alt\gamma\alt 151^{\circ} and 0^{\circ}\alt\delta\alt 75^{\circ} within 1σ\sigma standard deviation. It is noted that if allowing the standard deviation of the data to be more than 1σ\sigma, the two solutions could approach to one solution with a much larger region for the phases Îł\gamma and ÎŽ\delta. Direct CP asymme try aÏ”â€Čâ€Č(π−K+)a_{\epsilon''}^{(\pi^- K^+)} in B\rarrow \pi^-K^+ decay can be as large as the present experimental upper bound. Direct CP asymmetry aÏ”â€Čâ€Č(π+π−)a_{\epsilon''}^{(\pi^+\pi^-)} in B\rarrow \pi^-\pi^+ decay can reach up to about 40% at 1σ\sigma level.Comment: 14 Pages, ReVTeX, 5 figures, one figure (Fig.3) is correcte

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

    Get PDF
    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

    Get PDF
    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
    • 

    corecore