63,231 research outputs found
Identifying the Higgs Spin and Parity in Decays to Z Pairs
Higgs decays to Z boson pairs may be exploited to determine spin and parity
of the Higgs boson, a method complementary to spin-parity measurements in
Higgs-strahlung. For a Higgs mass above the on-shell ZZ decay threshold, a
model-independent analysis can be performed, but only by making use of
additional angular correlation effects in gluon-gluon fusion at the LHC and
gamma-gamma fusion at linear colliders. In the intermediate mass range, in
which the Higgs boson decays into pairs of real and virtual Z bosons, threshold
effects and angular correlations, parallel to Higgs-strahlung, may be adopted
to determine spin and parity, though high event rates will be required for the
analysis in practice.Comment: 14 pages, 2 postscript figure
Comment about pion electro-production and the axial form factors
The claim by Haberzettl (Phys.Rev.Lett.85 (2000) 3576) that the axial form
factor of the nucleon cannot be accessed through threshold pion
electroproduction is unfounded
Determining SUSY Parameters in Chargino Pair-Production in Collisions
In most supersymmetric theories, charginos , mixtures
of charged color-neutral gauginos and higgsinos, belong to the class of the
lightest supersymmetric particles. They are easy to observe at
colliders. By measuring the total cross sections and the left-right asymmetries
with polarized electron beams in , the chargino masses and the gaugino-higgsino mixing angles can be
determined. From these observables the fundamental SUSY parameters can be
derived: the SU(2) gaugino mass , the modulus and
of the higgsino mass parameter, and , the ratio of the
vacuum expectation values of the two neutral Higgs doublet fields. The
solutions are unique; the CP-violating phase can be determined
uniquely by analyzing effects due to the normal polarization of the charginos.Comment: 20 pages, 4 figures, uses axodraw.st
Quantum Phase Transitions in Josephson Junction Chains
We investigate the quantum phase transition in a one-dimensional chain of
ultra-small superconducting grains, considering both the self- and junction
capacitances. At zero temperature, the system is transformed into a
two-dimensional system of classical vortices, where the junction capacitance
introduces anisotropy in the interaction between vortices. This leads to the
superconductor-insulator transition of the Berezinskii-Kosterlitz-Thouless
type, as the ratios of the Josephson coupling energy to the charging energies
are varied. It is found that the junction capacitance plays a role similar to
that of dissipation and tends to suppress quantum fluctuations; nevertheless
the insulator region survives even for arbitrarily large values of the junction
capacitance.Comment: REVTeX+5 EPS figures, To appear in PRB Rapid
Remarks on the classification of quasitoric manifolds up to equivariant homeomorphism
We give three sufficient criteria for two quasitoric manifolds (M,M') to be
(weakly) equivariantly homeomorphic.
We apply these criteria to count the weakly equivariant homeomorphism types
of quasitoric manifolds with a given cohomology ring.Comment: 11 page
Reconstructing the Chargino System at Linear Colliders
In most supersymmetric theories charginos, , belong
to the class of the lightest supersymmetric particles. The chargino system can
be reconstructed completely in collider experiments:
. By measuring the total
cross sections and the asymmetries with polarized beams, the chargino masses
and the gaugino-higgsino mixing angles of these states can be determined
accurately. If only the lightest charginos are
kinematically accessible in a first phase of the machine, transverse beam
polarization or the measurement of chargino polarization in the final state is
needed to determine the mixing angles. From these observables the fundamental
SUSY parameters can be derived: the SU(2) gaugino mass , the modulus and
the cosine of the CP-violating phase of the higgsino mass parameter , and
, the ratio of the vacuum expectation values of the two
neutral Higgs doublet fields. The remaining two-fold ambiguity of the phase can
be resolved by measuring the normal polarization of the charginos. Sum rules of
the cross sections can be exploited to investigate the closure of the
two-chargino system.Comment: 25 pages, 6 figure
Capacitively coupled Josephson-junction chains: straight and slanted coupling
Two chains of ultrasmall Josephson junctions, coupled capacitively with each
other in the two different ways, straight and slanted coupling, are considered.
As the coupling capacitance increases, regardless of the coupling scheme, the
transport of particle-hole pairs in the system is found to drive the
quantum-phase transition at zero temperature, which is a
insulator-to-superfluid transition of the particle-hole pairs and belongs to
the Berezinskii-Kosterlitz-Thouless universal class. The different underlying
transport mechanisms for the two coupling schemes are reflected in the
difference between the transition points.Comment: REVTeX + 7 EPS figures, detailed version of cond-mat/980219
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