118670238
He–McKellar–Wilkens effect and scalar Aharonov–Bohm effect for a neutral particle based on the Lorentz symmetry violation
In this contribution, we discuss the He–McKellar–Wilkens effect and the scalar Aharonov–Bohm effect for neutral particles based on the Lorentz symmetry violation background, by showing that the background of the Lorentz symmetry violation yields Abelian quantum phases for a neutral particle. We also study the non-relativistic bound states for a neutral particle interacting with a Coulomb-like potential based on the Lorentz symmetry violation background given by a fixed vector field parallel to the radial direction.
118609457
Relativistic Landau-Aharonov-Casher quantization based on the Lorentz symmetry violation background
Based on the discussions about the Aharonov-Casher effect in the Lorentz symmetry violation background, we show that the analogue of the relativistic Landau quantization in the Aharonov-Casher setup can be achieved in the Lorentz-symmetry violation background.
119686840
On Aharonov–Casher scattering in a CPT-odd Lorentz-violating background
The effects of a Lorentz symmetry-violating background vector on Aharonov?Casher scattering in the nonrelativistic limit are considered. Using the self-adjoint extension method, we find that there is additional scattering for any value of the self-adjoint extension parameter and non-zero energy bound states for negative values of this parameter. Expressions for the energy bound states, phase-shift and scattering matrix are explicitly determined in terms of the self-adjoint extension parameter. The expression obtained for the scattering amplitude reveals that the helicity is not conserved in this scenario.
119697349
On the spin- 1/2 Aharonov-Bohm problem in conical space: Bound states, scattering and helicity nonconservation
In this work the bound state and scattering problems for a spin-1/2 particle undergone to an Aharonov-Bohm potential in a conical space in the nonrelativistic limit are consider ed. The presence of a �-function singularity, which comes from the Zeeman spin interaction with the magnetic flux tube, is addressed by the self-adjoint extension method. One of the advantages of the present approach is the determination of the self-adjoint extension parameter in terms of physics of the problem. Expressions for the energy bound states, phase-shift and S matrix are determined in terms of the self-adjoint extension parameter, which is explicitly determined in terms of the parameters of the problem. The relation between the bound state and zero modes and the failure of helicity conservation in the scattering problem and its relation with the gyromagnetic ratio g are discussed. Also, as an application, we consider the spin-1/2 AharonovBohm problem in conical space plus a two-dimensional isotropic harmonic oscillator.
119322655
Finiteness of the noncommutative supersymmetric Maxwell-Chern-Simons theory
Within the superfield approach, we prove the absence of UV/IR mixing in the three-dimensional noncommutative supersymmetric Maxwell-Chern-Simons theory at any loop order and demonstrate its finiteness in one, three, and higher loop orders.
199684869
Non-relativistic quantum dynamics on a cone: Schr\"{o}dinger versus Dirac Theory
14310669
A Study of Strange Particles Produced in Neutrino Neutral Current Interactions in the NOMAD Experiment
Results of a detailed study of strange particle production in neutrino neutral current interactions are presented using the data from the NOMAD experiment. Integral yields of neutral strange particles (K0s, Lambda, Lambda-bar) have been measured. Decays of resonances and heavy hyperons with an identified K0s or Lambda in the final state have been analyzed. Clear signals corresponding to K* and Sigma(1385) have been observed. First results on the measurements of the Lambda polarization in neutral current interactions have been obtained.
120676865
Topological search for the production of neutralinos and scalar particles
Abstract A search for scalar particles and neutralinos such as those predicted by supersymmetric models has been performed using a data sample of 4.4 million hadronic Z 0 decays recorded by the OPAL detector at the e + e − collider LEP. The production of such particles typically leads to event topologies consisting of an acoplanar pair of jets, or of a mono-jet, accompanied by sizeable missing energy owing to neutrinos and other undetectable neutral particles. Limits are obtained, at the 95% confidence level, on the masses and production rates of scalar particles produced in association with the Z 0 . Limits are also placed on neutralino production, for which an additional possible signature is also studied, events containing a single observed photon. Within the Minimal Supersymmetric Standard Model, the mass of the lightest neutralino is found to be larger than 12.5 GeV/ c 2 at 95% C.L., provided that tan β is larger than 1.5.
122943156
A measurement of the average bottom hadron lifetime
The average b hadron lifetime, τb, has been measured using approximately 3.5 million hadronic events collected with the OPAL detector at LEP between 1991 and 1994. A lifetime tag based on a neural network algorithm was used to select Z → bb̄ events. A secondary vertex reconstructed on the opposite side from the b-tag was used to measure the b hadron decay length. This was combined with an estimate of the b hadron momentum, allowing the b hadron decay time to be evaluated. The lifetime, τb = 1.611± 0.010 (stat)± 0.027 (syst) ps, was extracted from a fit involving the distribution of the 95 620 decay times reconstructed in the data and the corresponding distribution in Monte Carlo. (Submitted to Z. Phys. C) The OPAL Collaboration K. Ackerstaff8, G. Alexander23, J. Allison16, N. Altekamp5, K. Ametewee25, K.J. Anderson9, S. Anderson, S. Arcelli, S. Asai, D. Axen, G. Azuelos, A.H. Ball, E. Barberio, R.J. Barlow, R. Bartoldus, J.R. Batley, J. Bechtluft, C. Beeston, T. Behnke, A.N. Bell, K.W. Bell20, G. Bella23, S. Bentvelsen8, P. Berlich10, S. Bethke14, O. Biebel14, V. Blobel27, I.J. Bloodworth, J.E. Bloomer, M. Bobinski, P. Bock, H.M. Bosch, M. Boutemeur, B.T. Bouwens12, S. Braibant12, R.M. Brown20, H.J. Burckhart8, C. Burgard8, R. Bürgin10, P. Capiluppi, R.K. Carnegie, A.A. Carter, J.R. Carter, C.Y. Chang, D.G. Charlton, D. Chrisman4, P.E.L. Clarke15, I. Cohen23, J.E. Conboy15, O.C. Cooke16, M. Cuffiani2, S. Dado, C. Dallapiccola, G.M. Dallavalle, S. De Jong, L.A. del Pozo, K. Desch, M.S. Dixit7, E. do Couto e Silva12, M. Doucet18, E. Duchovni26, G. Duckeck34, I.P. Duerdoth16, J.E.G. Edwards, P.G. Estabrooks, H.G. Evans, M. Evans, F. Fabbri, P. Fath, F. Fiedler27, M. Fierro2, H.M. Fischer3, R. Folman26, D.G. Fong17, M. Foucher17, A. Fürtjes8, P. Gagnon, A. Gaidot, J.W. Gary, J. Gascon, S.M. Gascon-Shotkin, N.I. Geddes, C. Geich-Gimbel, F.X. Gentit, T. Geralis, G. Giacomelli, P. Giacomelli, R. Giacomelli, V. Gibson5, W.R. Gibson13, D.M. Gingrich30,a, D. Glenzinski9, J. Goldberg22, M.J. Goodrick5, W. Gorn, C. Grandi, E. Gross, J. Grunhaus M. Gruwé, C. Hajdu, G.G. Hanson, M. Hansroul8, M. Hapke13, C.K. Hargrove7, P.A. Hart9, C. Hartmann3, M. Hauschild8, C.M. Hawkes, R. Hawkings, R.J. Hemingway, M. Herndon, G. Herten, R.D. Heuer, M.D. Hildreth8, J.C. Hill5, S.J. Hillier1, T. Hilse10, P.R. Hobson25, R.J. Homer1, A.K. Honma, D. Horváth, R. Howard, R.E. Hughes-Jones, D.E. Hutchcroft, P. Igo-Kemenes11, D.C. Imrie25, M.R. Ingram16, K. Ishii24, A. Jawahery17, P.W. Jeffreys20, H. Jeremie, M. Jimack, A. Joly, C.R. Jones, G. Jones, M. Jones, R.W.L. Jones, U. Jost11, P. Jovanovic1, T.R. Junk8, D. Karlen6, K. Kawagoe24, T. Kawamoto24, R.K. Keeler28, R.G. Kellogg, B.W. Kennedy, B.J. King, J. Kirk, S. Kluth, T. Kobayashi, M. Kobel, D.S. Koetke, T.P. Kokott, M. Kolrep, S. Komamiya, T. Kress, P. Krieger, J. von Krogh11, P. Kyberd13, G.D. Lafferty16, H. Lafoux21, R. Lahmann17, W.P. Lai19, D. Lanske14, J. Lauber, S.R. Lautenschlager, J.G. Layter, D. Lazic, A.M. Lee, E. Lefebvre, D. Lellouch26, J. Letts2, L. Levinson26, C. Lewis15, S.L. Lloyd13, F.K. Loebinger16, G.D. Long17, M.J. Losty, J. Ludwig, A. Malik, M. Mannelli, S. Marcellini, C. Markus, A.J. Martin, J.P. Martin18, G. Martinez17, T. Mashimo24, W. Matthews25, P. Mättig3, W.J. McDonald30, J. McKenna, E.A. Mckigney, T.J. McMahon, A.I. McNab, R.A. McPherson, F. Meijers, S. Menke3, F.S. Merritt9, H. Mes7, J. Meyer27, A. Michelini2, G. Mikenberg26, D.J. Miller15, R. Mir, W. Mohr, A. Montanari, T. Mori, M. Morii, U. Müller, K. Nagai, I. Nakamura24, H.A. Neal8, B. Nellen3, B. Nijjhar16, R. Nisius8, S.W. O’Neale1, F.G. Oakham7, F. Odorici, H.O. Ogren, N.J. Oldershaw, T. Omori, M.J. Oreglia, S. Orito, J. Pálinkás, G. Pásztor, J.R. Pater, G.N. Patrick, J. Patt, M.J. Pearce, S. Petzold, P. Pfeifenschneider14, J.E. Pilcher9, J. Pinfold30, D.E. Plane8, P. Poffenberger28, B. Poli2, A. Posthaus, H. Przysiezniak, D.L. Rees, D. Rigby, S. Robertson, S.A. Robins, N. Rodning30, J.M. Roney28, A. Rooke15, E. Ros8, A.M. Rossi2, M. Rosvick28, P. Routenburg30, Y. Rozen, K. Runge, O. Runolfsson, U. Ruppel, D.R. Rust, R. Rylko, K. Sachs, E.K.G. Sarkisyan23, M. Sasaki24, C. Sbarra2, A.D. Schaile34, O. Schaile34, F. Scharf3, P. Scharff-Hansen, P. Schenk, B. Schmitt, S. Schmitt, M. Schröder, H.C. Schultz-Coulon10, M. Schulz8, M. Schumacher3, P. Schütz3, W.G. Scott20, T.G. Shears16, B.C. Shen, C.H. Shepherd-Themistocleous, P. Sherwood, G.P. Siroli, A. Sittler, A. Skillman15, A. Skuja17, A.M. Smith8, T.J. Smith28, G.A. Snow17, R. Sobie28, S. Söldner-Rembold, R.W. Springer, M. Sproston, A. Stahl, M. Steiert, K. Stephens, J. Steuerer, B. Stockhausen, D. Strom, F. Strumia, P. Szymanski, R. Tafirout,
48337486
A measurement of the average lifetime of b-flavoured baryons
Abstract The average lifetime of baryons containing a b quark has been measured with the OPAL detector using data collected between 1990 and 1992. Semileptonically decaying b-flavoured baryons which produce a Λ are identified through the charge correlation of the λ and lepton. The decay point of the baryon is estimated by the λ-lepton vertex, and the observed distribution of decay lengths is fitted to determine the average lifetime. In the data sample consisting of 261 right-sign and 104 wrong-sign λ-lepton charge combinations, the average b baryon lifetime is found to be τ = 1.05 +0.23 -0.20 ±0.08 ps, where the first error is statistical and the second systematic.
120521856
Measurement of the B0 and B+ lifetimes
Abstract From a data sample of approximately 240 000 hadronic Z 0 decays recorded during 1991 a sample of about 130 semileptonic B hadron decays containing a D 0 , D + or D ∗+ has been isolated. Using silicon microvertex detector information the decay vertices in these events have been reconstructed. The average B hadron lifetime of the mix of B hadrons in this event sample is measured to be 1.51 −0.14 +0.16 ±0.11 ps. From the distribution of decay times in the different samples the lifetimes of the B 0 and B + mesons are determined to be 1.51 −0.23−0.14 +0.24+0.12 ps and 1.51 −0.28−0.14 +0.30+0.12 ps, respectively. The measured ratio of the B + to B 0 lifetimes of 1.00 −0.25 +0.33 ±0.08 supports expectations that the lifetimes are similar.