131 research outputs found

### Three-Neutrino MSW Effect and the Lehmann Mass Matrix

Recent work on analytical solutions to the MSW equations for three neutrino
flavours is reviewed, with emphasis on the exponential density. Application to
a particular mass matrix, proposed by Lehmann, Newton and Wu, is also
discussed. Within this model, the experimental data allow a determination of
the three neutrino masses. They are found to be 0.002-0.004, 0.01 and 0.05 eV.Comment: 6 pages, LaTeX, 1 figure. Invited talk given at the conference
"Beyond the Desert 2002", 2-7 June 2002, Oulu, Finland, to be published in
the proceeding

### CP Investigations in the Higgs Sector

In a more general electroweak theory, there could be Higgs particles that are
odd under $CP$. When such particles decay via vector bosons to two
fermion-antifermion pairs, the momenta of those will be correlated in a way
which is determined by the $CP$ of the particle. Similarly, in the Bjorken
process correlations among momenta of the initial electron and final-state
fermions are sensitive to the $CP$ quantum number. Monte Carlo data on the
expected efficiency demonstrate that it should be possible to verify the scalar
character of an intermediate-mass Standard Model Higgs boson after three years
of data taking at a future linear collider. This is most likely not possible at
LEP2. Signals of possible presence of $CP$ violation in the Higgs sector are
briefly discussed.Comment: 12 pages, LaTex2e, plus 7 uuencoded figures. Invited paper, Third
Tallinn Symposium on Neutrino Physics, Lohusalu, Estonia, October 7-11, 199

### Maximal CP nonconservation in the Two-Higgs-Doublet Model

We study the simplest Two-Higgs-Doublet Model that allows for CP
nonconservation, where it can be parametrized by only one parameter in the
Higgs potential. Different concepts of maximal CP-nonconservation in the
gauge-Higgs and the quark-Higgs (Yukawa) sectors are compared. Maximal CP
nonconservation in the gauge-Higgs sector does normally not lead to maximal CP
nonconservation in the Yukawa sector, and vice versa.Comment: 22 pages, including figures. Invited talk given at the Cracow
Epiphany conference on heavy flavours, 3 - 6 January 2003, Cracow, Poland, a
shortened version to be published in Acta Physica Polonica, July 200

### Signals of $CP$ violation in Higgs decay

We consider an extension of the Standard Model where some Higgs particle is
not an eigenstate of $CP$, and discuss the possibility of extracting signals of
the resulting $CP$ violation. In the case of Higgs decay to four fermions we
study correlations among momenta of the final-state fermions. We discuss
observables which may demonstrate presence of $CP$ violation and identify a
phase shift $\delta$, which is a measure of the strength of $CP$ violation in
the Higgs-vector-vector coupling, and which can be measured directly in the
decay distribution. In addition to these angular correlations, we consider
correlations between energy differences. The former correlations include some
recently reported results, whereas the latter ones appear to provide a much
better probe for revealing $CP$ violation.Comment: 11 pages (5 figures in Postscript appended as uuencoded
tar-compressed file), LATEX (full postscript version available by anonymous
ftp at node VSFYS1.FI.UIB.NO in subdirectory OSLAND, file BERGEN94-06.PS),
Bergen Scientific/Technical Report No. 1994-0

### Light-Gluino Production at LEP

If gluinos are light, they will be produced in electron-positron annihilation
at LEP, not only by radiation in pairs off quarks and antiquarks, but also
without accompanying quark and antiquark jets. We here discuss the latter
process, pair production of gluinos, in a model with soft supersymmetry
breaking, allowing for mixing between the squarks. In much of the parameter
space of the Minimal Supersymmetric Model (MSSM) the cross section corresponds
to a $Z$ branching ratio above $10^{-5}$, even up to $10^{-4}$. A
non-observation of gluinos at this level restricts the allowed MSSM parameter
space.Comment: 8 pages, LaTex 2.09, 4 figures, uuencoded ps files Full ps file
available via anonymous ftp at
ftp://vsfys1.fi.uib.no/anonymous/kileng/NORDITA_9460.ps (Figures now
tar-compressed according to party line.

### More Series related to the Euler Series

We present results for infinite series appearing in Feynman diagram
calculations, many of which are similar to the Euler series. These include both
one-, two- and three-dimensional series. All these series can be expressed in
terms of zeta(2) and zeta(3).Comment: 17 pages, LaTeX, uses elsart.cl

### Perturbative Aspects of q-Deformed Dynamics

Within the framework of the q-deformed Heisenberg algebra a dynamical
equation of q-deformed quantum mechanics is discussed. The perturbative aspects
of the q-deformed Schr\"odinger equation are analyzed. General representations
of the additional momentum-dependent interaction originating from the
q-deformed effects are presented in two approaches. As examples, such
additional interactions related to the harmonic-oscillator potential and the
Morse potential are demonstrated.Comment: 10 pages, LaTeX, including 1 figur

### Some infinite series related to Feynman diagrams

Results are presented for some infinite series appearing in Feynman diagram
calculations, many of which are similar to the Euler series. These include both
one-, two- and three-dimensional series. The sums of these series can be
evaluated with the help of various integral representations for hypergeometric
functions, and expressed in terms of $\zeta(2)$, $\zeta(3)$, the Catalan
constant $G$ and ${\rm Cl}_2(\pi/3)$ where ${\rm Cl}_2(\theta)$ is Clausen's
function.Comment: 10 pages, LaTeX, 2 figures; presented at ICCAM-200

### Dyon mass bounds from electric dipole moments

Dyon loops give a contribution to the matrix element for light-by-light
scattering that violates parity and time-reversal symmetry. This effect induces
an electric dipole moment for the electron, of order $M^{-2}$, where $M$ is the
dyon mass. The current limit on the electric dipole moment of the electron
yields the lower mass bound M>{\cal O}(1)~\mbox{TeV}.Comment: LaTeX + 1 figure as uuencoded PostScript fil

### Roy Glauber and Asymptotic Diffraction Theory

This is a review of Glauber's asymptotic diffraction theory, in which
diffractive scattering is described in terms of interference between
semiclassical amplitudes, resulting from a stationary-phase approximation.
Typically two such amplitudes are sufficient to accurately describe elastic
scattering, but the stationary points are located at complex values of the
impact parameter. Their separation controls the interference pattern, and their
offsets from the real axis determine the overall fall-off with momentum
transfer. Asymptotically, at large momentum transfers, the stationary points
move towards singularities of the profile function. I also include some
reminiscences from our collaboration.Comment: 12 pages, contribution to SciPost Physics Proceedings: EFB 24. v2:
minor change

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