5,617 research outputs found
The role of energy-momentum conservation in emission of Cherenkov gluons
The famous formula for the emission angle of Cherenkov radiation should be
modified when applied to hadronic reactions because of recoil effects. They
impose the upper limit on the energy of the gluon emitted at a given angle.
Also, it leads to essential corrections to the nuclear refractive index value
as determined from the angular position of Cherenkov rings.Comment: 6
Single Leptoquark Production at and Colliders
We consider single production of leptoquarks (LQ's) at and
colliders, for two values of the centre-of-mass energy,
GeV and 1 TeV. We find that LQ's which couple within the first
generation are observable for LQ masses almost up to the kinematic limit, both
at and colliders, for the LQ coupling strength equal to
. The cross sections for single production of - and
-generation LQ's at colliders are too small to be observable.
In collisions, on the other hand, -generation LQ's with
masses much larger than can be detected. However,
-generation LQ's can be seen at colliders only for
masses at most , making their observation more probable via the
pair production mechanism.Comment: plain TeX, 14 pages, 6 figures (not included but available on
request), some minor changes to the text, one reference added, figures and
conclusions unchanged, UdeM-LPN-TH-93-152, McGill-93/2
Some combinatorial identities related to commuting varieties and Hilbert schemes
In this article we explore some of the combinatorial consequences of recent results relating the isospectral commuting variety and the Hilbert scheme of points in the plane
Determination of the Higgs-boson couplings and H-A mixing in the generalized SM-like Two Higgs Doublet Model
The feasibility of measuring the Higgs-boson properties at the Photon
Collider at TESLA has been studied in detail for masses between 200 and 350
GeV, using realistic luminosity spectra and detector simulation. We consider
the Two Higgs Doublet Model (II) with SM-like Yukawa couplings for h,
parametrized by only one parameter (tan(beta)). The combined measurement of the
invariant-mass distributions in the ZZ and W+W- decay-channels is sensitive to
both the two-photon width Gamma_{gamma gamma} and phase Phi_{gamma gamma}. From
the analysis including systematic uncertainties we found out that after one
year of Photon Collider running with nominal luminosity the expected precision
in the measurement of tan(beta) is of the order of 10%, for both light (h) and
heavy (H) scalar Higgs bosons. The H-A mixing angle Phi_{HA}, characterizing a
weak CP violation in the model with two Higgs doublets, can be determined to
about 100 mrad, for low tan(beta).Comment: 17 pages, 9 figures; published versio
On a Coherent Radioemission Mechanism in Quasars and in the Remains of Supernovae
Coherent radio emission mechanism in quasars and remains of supernova
Current in narrow channels of anisotropic superconductors
We argue that in channels cut out of anisotropic single crystal
superconductors and narrow on the scale of London penetration depth, the
persistent current must cause the transverse phase difference provided the
current does not point in any of the principal crystal directions. The
difference is proportional to the current value and depends on the anisotropy
parameter, on the current direction relative to the crystal, and on the
transverse channel dimension. An experimental set up to measure the transverse
phase is proposed.Comment: 3 pages, 1 figur
Evolution of Universe to the present inert phase
We assume that current state of the Universe can be described by the Inert
Doublet Model, containing two scalar doublets, one of which is responsible for
EWSB and masses of particles and the second one having no couplings to fermions
and being responsible for dark matter. We consider possible evolutions of the
Universe to this state during cooling down of the Universe after inflation. We
found that in the past Universe could pass through phase states having no DM
candidate. In the evolution via such states in addition to a possible EWSB
phase transition (2-nd order) the Universe sustained one 1-st order phase
transition or two phase transitions of the 2-nd order.Comment: 19 pages, 3 figure
The visible effect of a very heavy magnetic monopole at colliders
If a heavy Dirac monopole exists, the light-to-light scattering below the
monopole production threshold is enhanced due to strong coupling of monopoles
to photons. At the next Linear Collider with electron beam energy 250 GeV this
photon pair production could be observable at monopole masses less than 2.5-6.4
TeV in the mode or 3.7-10 TeV in the mode, depending on
the monopole spin. At the upgraded Tevatron such an effect is expected to be
visible at monopole masses below 1-2.5 TeV. The strong dependence on the
initial photon polarizations allows to find the monopole spin in experiments at
and colliders. We consider the production and
the production at and or colliders via the
same monopole loop. The possibility to discover these processes is
significantly lower than that of the case.Comment: 18 pages, 2 figures, RevTe
Dependence of the critical temperature on the Higgs field reparametrization
We show that, despite of the reparametrization symmetry of the Lagrangian
describing the interaction between a scalar field and gauge vector bosons, the
dynamics of the Higgs mechanism is really affected by the representation gauge
chosen for the Higgs field. Actually, we find that, varying the parametrization
for the two degrees of freedom of the complex scalar field, we obtain different
expressions for the Higgs mass: in its turn this entails different expressions
for the critical temperatures, ranging from zero to a maximum value, as well as
different expressions for other basic thermodynamical quantities.Comment: revtex, 12 pages, 2 eps figure
- …