3,506 research outputs found
Complementarity and Scientific Rationality
Bohr's interpretation of quantum mechanics has been criticized as incoherent
and opportunistic, and based on doubtful philosophical premises. If so Bohr's
influence, in the pre-war period of 1927-1939, is the harder to explain, and
the acceptance of his approach to quantum mechanics over de Broglie's had no
reasonable foundation. But Bohr's interpretation changed little from the time
of its first appearance, and stood independent of any philosophical
presuppositions. The principle of complementarity is itself best read as a
conjecture of unusually wide scope, on the nature and future course of
explanations in the sciences (and not only the physical sciences). If it must
be judged a failure today, it is not because of any internal inconsistency.Comment: 29 page
Monodromy and Kawai-Lewellen-Tye Relations for Gravity Amplitudes
We are still learning intriguing new facets of the string theory motivated
Kawai-Lewellen-Tye (KLT) relations linking products of amplitudes in Yang-Mills
theories and amplitudes in gravity. This is very clearly displayed in
computations of N=8 supergravity where the perturbative expansion show a vast
number of similarities to that of N=4 super-Yang-Mills. We will here
investigate how identities based on monodromy relations for Yang-Mills
amplitudes can be very useful for organizing and further streamlining the KLT
relations yielding even more compact results for gravity amplitudes.Comment: 6 pages, 12th Marcel Grossman meeting 200
String theory and the KLT-relations between gravity and gauge theory including external matter
We consider the Kawai-Lewellen-Tye (KLT) factorizations of gravity scalar-leg
amplitudes into products of scalar-leg Yang-Mills amplitudes. We check and
examine the factorizations at O(1) in and extend the analysis by
considering KLT-mapping in the case of generic effective Lagrangians for
Yang-Mills theory and gravity.Comment: 7 pages, ReVTeX4, references updated, changes to text and typos
correcte
Explicit Cancellation of Triangles in One-loop Gravity Amplitudes
We analyse one-loop graviton amplitudes in the field theory limit of a
genus-one string theory computation. The considered amplitudes can be
dimensionally reduced to lower dimensions preserving maximal supersymmetry. The
particular case of the one-loop five-graviton amplitude is worked out in detail
and explicitly features no triangle contributions. Based on a recursive form of
the one-loop amplitude we investigate the contributions that will occur at
n-point order in relation to the ``no-triangle'' hypothesis of N=8
supergravity. We argue that the origin of unexpected cancellations observed in
gravity scattering amplitudes is linked to general coordinate invariance of the
gravitational action and the summation over all orderings of external legs.
Such cancellations are instrumental in the extraordinary good ultra-violet
behaviour of N=8 supergravity amplitudes and will play a central role in
improving the high-energy behaviour of gravity amplitudes at more than one
loop.Comment: 25 pages. 2 eps pictures, harvmac format. v2: version to appear in
JHEP. Equations (3.9), (3.12) and minor typos correcte
Absence of Triangles in Maximal Supergravity Amplitudes
From general arguments, we show that one-loop n-point amplitudes in
colourless theories satisfy a new type of reduction formula. These lead to the
existence of cancellations beyond supersymmetry. Using such reduction relations
we prove the no-triangle hypothesis in maximal supergravity by showing that in
four dimensions the n-point graviton amplitude contain only scalar box integral
functions. We also discuss the reduction formulas in the context of gravity
amplitudes with less and no supersymmetry.Comment: 23 pages, RevTeX4 format. v2: Expanded version with a new section
providing some extra background material and an overview of the general
arguments. Minors typos have been corrected. Version to be publishe
Gravitino Interactions from Yang-Mills Theory
We fabricate gravitino vertex interactions using as only input on-shell
Yang-Mills amplitudes and the Kawai-Lewellen-Tye gauge theory / gravity
relations. A useful result of this analysis is simpler tree-level Feynman rules
for gravitino scattering than in traditional gauges. All results are explicitly
verified until five point scattering.Comment: 17 pages, 10 figures, REVTe
On the relation between models and the interacting boson model
The connections between the models (the original E(5) using an
infinite square well, , and ), based
on particular solutions of the geometrical Bohr Hamiltonian with
-unstable potentials, and the interacting boson model (IBM) are
explored. For that purpose, the general IBM Hamiltonian for the
transition line is used and a numerical fit to the different models
energies is performed, later on the obtained wavefunctions are used to
calculate B(E2) transition rates. It is shown that within the IBM one can
reproduce very well all these models. The agreement is the best for
and reduces when passing through ,
and E(5), where the worst agreement is obtained (although still very good for a
restricted set of lowest lying states). The fitted IBM Hamiltonians correspond
to energy surfaces close to those expected for the critical point. A phenomenon
similar to the quasidynamical symmetry is observed
Quadrupole collective variables in the natural Cartan-Weyl basis
The matrix elements of the quadrupole collective variables, emerging from
collective nuclear models, are calculated in the natural Cartan-Weyl basis of
O(5) which is a subgroup of a covering structure. Making
use of an intermediate set method, explicit expressions of the matrix elements
are obtained in a pure algebraic way, fixing the -rotational structure
of collective quadrupole models.Comment: submitted to Journal of Physics
Relationship between X(5)-models and the interacting boson model
The connections between the X(5)-models (the original X(5) using an infinite
square well, X(5)-, X(5)-, X(5)-, and
X(5)-), based on particular solutions of the geometrical Bohr
Hamiltonian with harmonic potential in the degree of freedom, and the
interacting boson model (IBM) are explored. This work is the natural extension
of the work presented in [1] for the E(5)-models. For that purpose, a quite
general one- and two-body IBM Hamiltonian is used and a numerical fit to the
different X(5)-models energies is performed, later on the obtained wave
functions are used to calculate B(E2) transition rates. It is shown that within
the IBM one can reproduce well the results for energies and B(E2) transition
rates obtained with all these X(5)-models, although the agreement is not so
impressive as for the E(5)-models. From the fitted IBM parameters the
corresponding energy surface can be extracted and it is obtained that,
surprisingly, only the X(5) case corresponds in the moderate large N limit to
an energy surface very close to the one expected for a critical point, while
the rest of models seat a little farther.Comment: Accepted in Physical Review
The Complete KLT-Map Between Gravity and Gauge Theories
We present the complete map of any pair of super Yang-Mills theories to
supergravity theories as dictated by the KLT relations in four dimensions.
Symmetries and the full set of associated vanishing identities are derived. A
graphical method is introduced which simplifies counting of states, and helps
in identifying the relevant set of symmetries.Comment: 41 pages, 16 figures, published version, typos corrected, references
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