759 research outputs found
On the Relationship of Quantum Mechanics to Classical Electromagnetism and Classical Relativistic Mechanics
Some connections between quantum mechanics and classical physics are
explored. The Planck-Einstein and De Broglie relations, the wavefunction and
its probabilistic interpretation, the Canonical Commutation Relations and the
Maxwell--Lorentz Equation may be understood in a simple way by comparing
classical electromagnetism and the photonic description of light provided by
classical relativistic kinematics. The method used may be described as `inverse
correspondence' since quantum phenomena become apparent on considering the low
photon number density limit of classical electromagnetism. Generalisation to
massive particles leads to the Klein--Gordon and Schr\"{o}dinger Equations. The
difference between the quantum wavefunction of the photon and a classical
electromagnetic wave is discussed in some detail.Comment: 14 pages, no figures, no table
Derivation of the Lorentz Force Law, the Magnetic Field Concept and the Faraday-Lenz Law using an Invariant Formulation of the Lorentz Transformation
It is demonstrated how the right hand sides of the Lorentz Transformation
equations may be written, in a Lorentz invariant manner, as 4--vector scalar
products. This implies the existence of invariant length intervals analogous to
invariant proper time intervals. This formalism, making essential use of the
4-vector electromagnetic potential concept, provides a short derivation of the
Lorentz force law of classical electrodynamics, the conventional definition of
the magnetic field, in terms of spatial derivatives of the 4--vector potential
and the Faraday-Lenz Law. An important distinction between the physical
meanings of the space-time and energy-momentum 4--vectors is pointed out.Comment: 15 pages, no tables 1 figure. Revised and extended version of
physics/0307133 Some typos removed and minor text improvements in this
versio
A Study of the LEP and SLD Measurements of
A systematic study is made of the data dependence of the parameter
, 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 level, is found to vary in the range from
1.7 to 2.9 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.Comment: 15 pages 7 figures 7 table
Fitting Precision Electroweak Data with Exotic Heavy Quarks
The 1999 precision electroweak data from LEP and SLC persist in showing some
slight discrepancies from the assumed standard model, mostly regarding and
quarks. We show how their mixing with exotic heavy quarks could result in a
more consistent fit of all the data, including two unconventional
interpretations of the top quark.Comment: 7 pages, no figure, 2 typos corrected, 1 reference update
New Axial Interactions at a TeV
We consider a heavy fourth family with masses lying in the symmetry breaking
channel of a new strong gauge interaction. This interaction generates a heavy
quark axial-type operator, whose effects can be enhanced through multiple
insertions. In terms of the strength of this operator we can express new
negative contributions to the S and T parameters and the shifts of the Z
couplings to the third family. In particular we find that the new contribution
to T is strongly constrained by the experimental constraints on the Z coupling
to the tau.Comment: 14 pages, 1 figure, PRD versio
Convergence and Gauge Dependence Properties of the Resummed One-loop Quark-Quark Scattering Amplitude in Perturbative QCD
The one-loop QCD effective charge for quark-quark scattering
is derived by diagrammatic resummation of the one-loop amplitude using an
arbitary covariant gauge. Except for the particular choice of gauge parameter
, is found to {\it increase} with increasing
physical scale, , as or . For ,
decreases with increasing and satisfies a renormalisation group equation.
Also, except for the case , convergence radii of geometric series
are found to impose upper limits on .Comment: 28 pages, 5 tables, 5 figures. v3 The one-loop amplitudes in Section
2 are recalculated using dimensional regularisation, and several errors in
the on-shell calculation of Reference[1] are pointed out. v4 one figure
removed one added. Three tables and new text in Section 5 added. Published
versio
The Experimental Status of the Standard Electroweak Model at the End of the LEP-SLC Era
A method is proposed to calculate the confidence level for agreement of data
with the Standard Model (SM) by combining information from direct and indirect
Higgs Boson searches. Good agreement with the SM is found for
GeV using the observables most sensitive to : and . In
particular, quantum corrections, as predicted by the SM, are observed with a
statistical significance of forty-four standard deviations. However, apparent
deviations from the SM of 3.7 and 2.8 are found for the Z and right-handed Zb couplings respectively. The
maximum confidence level for agreement with the SM of the entire data set
considered is for GeV. The reason why
confidence levels about an order of magnitude higher than this have been
claimed for global fits to similar data sets is explained.Comment: 47 pages, 8 figures, 24 tables. An in-depth study of statistical
issues related to the comparison of precision EW data to the S
Relating a gluon mass scale to an infrared fixed point in pure gauge QCD
We show that in pure gauge QCD (or any pure non-Abelian gauge theory) the
condition for the existence of a global minimum of energy with a gluon (gauge
boson) mass scale also implies the existence of a fixed point of the
function. We argue that the frozen value of the coupling constant found in some
solutions of the Schwinger-Dyson equations of QCD can be related to this fixed
point. We also discuss how the inclusion of fermions modifies this property.Comment: 4 pages, Revtex - Added some clarifying comments and new reference
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 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 , if the
effective charge \aefmu respects both quantum mechanical superposition and
renormalisation scale invariance. Limits on the values of or the
electron mass are obtained within the Standard Electroweak Model by requiring
convergence of \aefmz.Comment: 18 pages, 3 tables 4 figure
The Indirect Limit on the Standard Model Higgs Boson Mass from the Precision FERMILAB, LEP and SLD Data
Standard Model fits are performed on the most recent leptonic and b quark Z
decay data from LEP and SLD, and FERMILAB data on top quark production, to
obtain and . Poor fits are obtained, with confidence levels
2%. Removing the b quark data improves markedly the quality of the fits and
reduces the 95% CL upper limit on by 50 GeV.Comment: 6 pages 3 tables i figur
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