37,827 research outputs found
On the smallness of the cosmological constant in SUGRA models
In no--scale supergravity global symmetries protect local supersymmetry and a
zero value for the cosmological constant. We consider the breakdown of these
symmetries and present a minimal SUGRA model motivated by the multiple point
principle, in which the total vacuum energy density is naturally tiny. In order
to reproduce the observed value of the cosmological constant and preserve gauge
coupling unification, an additional pair of --plets of superfields
has to be included in the particle content of the considered model. These extra
fields have masses of the order of the supersymmetry breaking scale; so they
can be detected at future colliders. We also discuss the supersymmetry
breakdown and possible solution of the cosmological constant problem by MPP in
models with an enlarged gauge symmetry.Comment: 28 pages, 3 figures, some minor changes to the text, references adde
Multiple point principle as a mechanism for the suppression of FCNC and CP--violation phenomena in the 2HDM
We argue that multiple point principle (MPP) can be used to ensure CP
conservation and the absence of flavour changing neutral currents within the
two Higgs doublet model (2HDM). We also discuss Higgs phenomenology in the MPP
inspired 2HDM.Comment: Submitted for the SUSY07 proceedings, 4 pages, LaTeX, 2 eps
figures,CERN preprint number added, references update
Law Behind Second Law of Thermodynamics --Unification with Cosmology--
In an abstract setting of a general classical mechanical system as a model
for the universe we set up a general formalism for a law behind the second law
of thermodynamics, i.e. really for "initial conditions". We propose a
unification with the other laws by requiring similar symmetry and locality
properties.Comment: 17 page
Collective Fields for QCD
A gauge-symmetric approach to effective Lagrangians is described with special
emphasis on derivations of effective low-energy Lagrangians from QCD. The
examples we discuss are based on exact rewritings of cut-off QCD in terms of
new collective degrees of freedom. These cut-off Lagrangians are thus
``effective'' in the sense that they explicitly contain some of the physical
long-distance degrees of freedom from the outset.(Talk presented by P.H.
Damgaard at the workshop on ``Quantum Field Theoretical Methods in High Energy
Physics'', Kyffhauser, Germany, Sept. 1993. To appear in those proceedings).Comment: LaTeX, 12 pages, CERN--TH-7035/9
On the Smallness of the Cosmological Constant in SUGRA Models Inspired by Degenerate Vacua
In the no-scale supergravity global symmetries protect local supersymmetry
and a zero value for the cosmological constant. The breakdown of these
symmetries, which ensures the vanishing of the vacuum energy density, results
in a set of degenerate vacua with broken and unbroken supersymmetry leading to
the natural realisation of the multiple point principle (MPP). In the MPP
inspired SUGRA models the cosmological constant is naturally tiny.Comment: Parallel talk at SUSY09, Boston, USA, June 2009, 5 page
The spatial relation between the event horizon and trapping horizon
The relation between event horizons and trapping horizons is investigated in
a number of different situations with emphasis on their role in thermodynamics.
A notion of constant change is introduced that in certain situations allows the
location of the event horizon to be found locally. When the black hole is
accreting matter the difference in area between the two different horizons can
be many orders of magnitude larger than the Planck area. When the black hole is
evaporating the difference is small on the Planck scale. A model is introduced
that shows how trapping horizons can be expected to appear outside the event
horizon before the black hole starts to evaporate. Finally a modified
definition is introduced to invariantly define the location of the trapping
horizon under a conformal transformation. In this case the trapping horizon is
not always a marginally outer trapped surface.Comment: 16 pages, 1 figur
Why Nature has made a choice of one time and three space coordinates?
We propose a possible answer to one of the most exciting open questions in
physics and cosmology, that is the question why we seem to experience four-
dimensional space-time with three ordinary and one time dimensions. We have
known for more than 70 years that (elementary) particles have spin degrees of
freedom, we also know that besides spin they also have charge degrees of
freedom, both degrees of freedom in addition to the position and momentum
degrees of freedom. We may call these ''internal degrees of freedom '' the
''internal space'' and we can think of all the different particles, like quarks
and leptons, as being different internal states of the same particle. The
question then naturally arises: Is the choice of the Minkowski metric and the
four-dimensional space-time influenced by the ''internal space''?
Making assumptions (such as particles being in first approximation massless)
about the equations of motion, we argue for restrictions on the number of space
and time dimensions. (Actually the Standard model predicts and experiments
confirm that elementary particles are massless until interactions switch on
masses.)
Accepting our explanation of the space-time signature and the number of
dimensions would be a point supporting (further) the importance of the
''internal space''.Comment: 13 pages, LaTe
Generalized dual symmetry of nonabelian theories, monopoles and dyons
In the present talk we present an investigation of nonabelian SU(N) gauge
theories, describing a system of fields with non--dual g and dual \tilde g
charges and revealing the generalized dual symmetry. The Zwanziger type action
is suggested. The renormalization group equations for pure nonabelian theories,
in particular for pure SU(3)\times\widetilde{SU(3)} gauge theory (as an
example) are analysed. We consider not only monopoles, but also dyons. The
behaviour of the QCD total beta--function is investigated. It was shown that
this beta--function is antisymmetric under the interchange
\alpha\leftrightarrow\frac 1\alpha (here \alpha\equiv\alpha_s), and has zero
("fixed point") at \alpha = 1. Monopoles, or dyons, are responsible for the
phase transition. Considering critical points at \alpha_1\approx 0.4 and
\alpha_2\approx 2.5, we give an explanation of the freezing of \alpha_s.Comment: 15 pages, 5 figures, Presented at the 12th Lomonosov Conference on
Elementary Particle Physics, Moscow State University, Moscow, 25-31 August,
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