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J. H. Field

Publications and source records attributed to J. H. Field.

70 records · Page 4Linked to original sources
arXiv2002

A Covariant Path Amplitude Description of Flavour Oscillations: The Gribov-Pontecorvo Phase for Neutrino Vacuum Propagation is Right

An extended study is performed of geometrical and kinematical assumptions used in calculations of the neutrino oscillation phase. The almost universally employed `equal velocity' assumption, in which all neutrino mass eigenstates are produced at the same time, is shown to underestimate, by a factor of two, the neutrino propagation contribution to the phase. Taking properly into account, in a covariant path amplitude calculation, the incoherent nature of neutrino production as predicted by the Standard Model, results in an important source propagator contribution to the phase. It is argued that the commonly discussed Gaussian `wave packets' have no basis within quantum mechanics and are the result of a confused amalgam of quantum and classical wave concepts.

hep-ph↗
arXiv2002

A Phenomenological Analysis of Gluon Mass Effects in Inclusive Radiative Decays of the $\rm{J/ψ}$ and $Υ

The shapes of the inclusive photon spectra in the processes $\Jp \to γX$ and $\Up \to γX$ have been analysed using all available experimental data. Relativistic, higher order QCD and gluon mass corrections were taken into account in the fitted functions. Only on including the gluon mass corrections, were consistent and acceptable fits obtained. Values of $0.721^{+0.016}_{-0.068}$ GeV and $1.18^{+0.09}_{-0.29}$ GeV were found for the effective gluon masses (corresponding to Born level diagrams) for the $\Jp$ and $\Up$ respectively. The width ratios $Γ(V \to {\rm hadrons})/Γ(V \to γ+ {\rm hadrons}) V=\Jp, \Up$ were used to determine $α_s(1.5 {\rm GeV})$ and $α_s(4.9 {\rm GeV})$. Values consistent with the current world average $α_s$ were obtained only when gluon mass correction factors, calculated using the fitted values of the effective gluon mass, were applied. A gluon mass $\simeq 1$ GeV, as suggested with these results, is consistent with previous analytical theoretical calculations and independent phenomenological estimates, as well as with a recent, more accurate, lattice calculation of the gluon propagator in the infra-red region.

hep-ph↗
arXiv2002

Study of Rapidity Gap Events in Hadronic Z Decays with the L3 Detector

A search is performed in symmetric 3-jet hadronic Z decay events for evidence of colour singlet exchange and for colour reconnection effects predicted by the Rathsman model. Asymmetries in particle flow and the angular separation of particles are found to be sensitive to such effects. 95% upper limits of 7-9% are found for the fraction of colour singlet exchange, and of 0.93% for the colour reconnection parameter $R_0$ (default value 0.1) of the Rathsman model.

hep-ex↗
arXiv2001

The Description of Neutrino and Muon Oscillations by Interfering Amplitudes of Classical Space-Time Paths

Particle oscillations following neutrino production processes are analysed within Feynman's path amplitude formulation of quantum mechanics. Consideration of the temporal sequence of production and detection events reveals an important contribution to the oscillation phase from the space-time propagator of the decaying source particle. Formulae are derived for spatial neutrino oscillations following pion decay (at rest and in flight), muon decay and nuclear $β$-decay at rest, as well as for similar muon oscillations after pion decay at rest and in flight. In all cases studied, the neutrino oscillation phases found differ from the conventionally used one. A concise critical review is made of previous treatments of the quantum mechanics of neutrino and muon oscillations.

hep-ph↗
arXiv2001

A Covariant Feynman Path Amplitude Calculation of Neutrino and Muon Oscillations

Predictions are presented for the oscillation phase in neutrino oscillations following pion decay at rest and in flight, muon decay and nuclear $β-$decay at rest as well as for muon oscillations following pion decay at rest and in flight. The neutrino oscillation phases found disagree with the conventionally used value: $ϕ_{12} = Δm^2 L/(2P)$. The same oscillation phase is found for neutrino and muon oscillations following pion decay at rest. Shortcomings of previous treatments of the quantum mechanics of neutrino oscillations are commented on.

hep-ph↗
arXiv2001

Space-Time Exchange Invariance: Special Relativity as a Symmetry Principle

Special relativity is reformulated as a symmetry property of space-time: Space-Time Exchange Invariance. The additional hypothesis of spatial homogeneity is then sufficient to derive the Lorentz transformation without reference to the traditional form of the Principle of Special Relativity. The kinematical version of the latter is shown to be a consequence of the Lorentz transformation. As a dynamical application, the laws of electrodynamics and magnetodynamics are derived from those of electrostatics and magnetostatics respectively. The 4-vector nature of the electromagnetic potential plays a crucial role in the last two derivations.

physics.class-ph↗
arXiv2000

Two Novel Special Relativistic Effects: Space Dilatation and Time Contraction

The conventional discussion of the observed distortions of space and time in Special Relativity (the Lorentz-Fitzgerald Contraction and Time Dilatation) is extended by considering observations, from a stationary frame, of : (i) objects moving with constant velocity and uniformly illuminated during a short time $τ_L$ (their `Luminous Proper Time') in their rest frame; these may be called `Transient Luminous Objects' and (ii) a moving, extended, array of synchronised `equivalent clocks' in a common inertial frame. Application of the Lorentz Transformation to (i) shows that such objects, observed from the stationary frame with coarse time resolution in a direction perpendicular to their direction of motion are seen to be at rest but {\it longer} in the direction of the relative velocity $\vec{v}$ by a factor $1/\sqrt{1-(v/c)^2}$ (Space Dilatation) and to (ii) that the moving equivalent clock at any fixed position in the rest frame of the stationary observer is seen to be running {\it faster} than a similar clock at rest by the factor $1/\sqrt{1-(v/c)^2}$ (Time Contraction). All four space-time `effects' of Special Relativity are simply classified in terms of the projective geometry of space-time, and the close analogy of these effects to linear spatial perspective is pointed out.

physics.pop-ph↗
arXiv2000

Mass and Coupling Constant Limits from Convergence Conditions on the Effective Charge in QED

The massless fermion limit of QED is discussed. For on-shell renormalisation the high energy behaviour fixes no lower limit on the mass of the lightest fermion if the fine structure constant $α$ is allowed to vary. The choice of an arbitary (space-like) subtraction point does, however, fix a lower limit on the mass of the lightest fermion, for any subtraction scale $μ$, if the effective charge $\aefmu$ respects both quantum mechanical superposition and renormalisation scale invariance. Limits on the values of $α$ or the electron mass are obtained within the Standard Electroweak Model by requiring convergence of $\aefmz$.

hep-ph↗
arXiv1999

A Study of the LEP and SLD Measurements of $A_b$

A systematic study is made of the data dependence of the parameter $A_{\rm{b}}$, that, since 1995, has shown a deviation from the Standard Model prediction of between 2.4 and 3.1 standard deviations. Issues addressed include: the effect of particular measurements, values found by individual experiments, LEP/SLD comparison, and the treatment of systematic errors. The effect, currently at the 2.4$σ$ level, is found to vary in the range from 1.7$σ$ to 2.9$σ$ by excluding marginal or particularly sensitive data. Since essentially the full LEP and SLD Z decay data sets are now analysed the meaning of the deviation, (new physics, or marginal statistical fluctuation) is unlikely to be given by the present generation of colliders.

hep-ex↗
arXiv1999

Z-Decays to b Quarks and the Higgs Boson Mass

A model independent analysis of the most recent averages of precision electroweak data from LEP and SLD finds a 3$σ$ deviation of the parameter $A_b$ from the Standard Model prediction. The fitted value of $m_H$ shows a strong dependence on the inclusion or exclusion of b quark data, and the Standard Model fits have poor confidence levels of a few percent when the latter are included. The good fits obtained to lepton data, c quark data and the directly measured top quark mass, give $m_t = 171.2_{-3.8}^{+3.7}$ GeV and indicate that the Higgs boson mass is most likely less than 200 GeV.

hep-ph↗
arXiv1999

Space Time Measurements in Special Relativity

The conventional discussion of apparent distortions of space and time in Special Relativity (the Lorentz-Fitzgerald Contraction and Time Dilatation) is extended by considering observations of : (i) moving objects of limited lifetime in their own rest frame (`transient luminous objects') and (ii) a moving extended array of synchronised `equivalent clocks' in a common inertial frame. Application of the Lorentz Transformation to (i) shows that such objects, viewed with coarse time resolution, appear to be longer in the direction of the relative velocity $\vec{v}$ by a factor $1/\sqrt{1-(v/c)^2}$ (Space Dilatation) and to (ii) that the moving equivalent clock that appears at any fixed position in the rest frame of an inertial observer appears to be running faster than a similar clock at rest by the factor $1/\sqrt{1-(v/c)^2}$ (Time Contraction). The actual appearance of moving objects and clocks, taking into account light propagation time delays, as well as the effect of the Lorentz Transformation, is also discussed.

physics.pop-ph↗
arXiv1998

A Model Independent Analysis of LEP and SLD Data on Z-Decays; is the Standard Model Confirmed?

A model independent analysis has been performed on the LEP and SLD data on Z decays. Using only very weak theoretical assumptions, the effective vector and axial-vector couplings of leptons, c quarks and b quarks have been extracted. Although the lepton and c quark couplings agree well with Standard Model predictions, those of the b quark show deviations of more than three standard deviations. The effect is mainly in the right-handed b quark coupling, the left-handed coupling being consistent (at the 2$σ$ level) with the Standard Model prediction. The probability that the observed deviations of all the measured effective couplings are statistical fluctuations from lepton universality and the Standard Model is estimated to be 0.9%. The estimated probability that the deviations in the leptonic and b quark couplings alone are a fluctuation is 0.18%. A thorough discussion is made of the internal consistency of the different measurements contributing to the average values $A_l$ and $A_b$ used to extract the b quark couplings, as well as possible sources of systematic error that may not, hitherto, have been taken into account. Excluding \tpol~ measurements, which show internal inconsistencies, from the averages increases the deviations of the extracted b quark couplings from the Standard Model predictions to the four standard deviation level.

hep-ph↗
arXiv1998

Indications for an Anomalous Right-Handed Coupling of the b-Quark from a Model Independent Analysis of LEP and SLD Data on Z-Decays

A model independent analysis is made using the LEP and SLD data on Z decays available at the end of 1996. The effective weak coupling constants of leptons, c quarks and b quarks are extracted. Except for the right-handed b quark coupling, they all agree well with the predictions of the Standard Electroweak Model for $m_t = 172$ GeV and $m_H = 263$ GeV. The right-handed b quark coupling is found to be 42% and 3.2 standard deviations above the Standard Model prediction.

hep-ph↗
arXiv1995

BHAGENE3, a Monte Carlo Event Generator for Lepton Pair Production and Wide Angle Bhabha Scattering in $e^{+} e^{-}$ Collisions Near the Z-Peak

A new Monte Carlo event generator for wide angle Bhabha scattering and muon pair production in $e^+e^-$ collisions is described. The program includes complete one-loop electroweak corrections, and QED radiative corrections. The O($α$) QED correction uses the exact matrix element. Higher order QED corrections are included in an improved soft photon approximation with exponentiation of initial state radiation. Events are generated in the full phase space of the final state including explicit mass effects in the region of collinear mass singularities. The program is intended for centre of mass energies around and above the Z peak and for Bhabha scattering at angles greater than $10^{\circ}$ .

hep-ph↗