878 research outputs found
Strings, T-duality breaking, and nonlocality without the shortest distance
T-duality of string theory suggests nonlocality manifested as the shortest
possible distance. As an alternative, we suggest a nonlocal formulation of
string theory that breaks T-duality at the fundamental level and does not
require the shortest possible distance. Instead, the string has an objective
shape in spacetime at all length scales, but different parts of the string
interact in a nonlocal Bohmian manner.Comment: 7 pages, revised, to appear in Eur. Phys. J.
Boson-fermion unification, superstrings, and Bohmian mechanics
Bosonic and fermionic particle currents can be introduced in a more unified
way, with the cost of introducing a preferred spacetime foliation. Such a
unified treatment of bosons and fermions naturally emerges from an analogous
superstring current, showing that the preferred spacetime foliation appears
only at the level of effective field theory, not at the fundamental superstring
level. The existence of the preferred spacetime foliation allows an objective
definition of particles associated with quantum field theory in curved
spacetime. Such an objective definition of particles makes the Bohmian
interpretation of particle quantum mechanics more appealing. The superstring
current allows a consistent Bohmian interpretation of superstrings themselves,
including a Bohmian description of string creation and destruction in terms of
string splitting. The Bohmian equations of motion and the corresponding
probabilistic predictions are fully relativistic covariant and do not depend on
the preferred foliation.Comment: 30 pages, 1 figure, revised, to appear in Found. Phy
Would Bohr be born if Bohm were born before Born?
I discuss a hypothetical historical context in which a Bohm-like
deterministic interpretation of the Schrodinger equation could have been
proposed before the Born probabilistic interpretation and argue that in such a
context the Copenhagen (Bohr) interpretation would probably have never achieved
great popularity among physicists.Comment: 5 pages, revised, accepted for publication in Am. J. Phy
Quantum mechanics: Myths and facts
A common understanding of quantum mechanics (QM) among students and practical
users is often plagued by a number of "myths", that is, widely accepted claims
on which there is not really a general consensus among experts in foundations
of QM. These myths include wave-particle duality, time-energy uncertainty
relation, fundamental randomness, the absence of measurement-independent
reality, locality of QM, nonlocality of QM, the existence of well-defined
relativistic QM, the claims that quantum field theory (QFT) solves the problems
of relativistic QM or that QFT is a theory of particles, as well as myths on
black-hole entropy. The fact is that the existence of various theoretical and
interpretational ambiguities underlying these myths does not yet allow us to
accept them as proven facts. I review the main arguments and counterarguments
lying behind these myths and conclude that QM is still a
not-yet-completely-understood theory open to further fundamental research.Comment: 51 pages, pedagogic review, revised, new references, to appear in
Found. Phy
Inappropriateness of the Rindler quantization
It is argued that the Rindler quantization is not a correct approach to study
the effects of acceleration on quantum fields. First, the "particle"-detector
approach based on the Minkowski quantization is not equivalent to the approach
based on the Rindler quantization. Second, the event horizon, which plays the
essential role in the Rindler quantization, cannot play any physical role for a
local noninertial observer.Comment: 3 pages, accepted for publication in Mod. Phys. Lett.
Charge and spin fractionalization in strongly correlated topological insulators
We construct an effective topological Landau-Ginzburg theory that describes
general SU(2) incompressible quantum liquids of strongly correlated particles
in two spatial dimensions. This theory characterizes the fractionalization of
quasiparticle quantum numbers and statistics in relation to the topological
ground-state symmetries, and generalizes the Chern-Simons, BF and hierarchical
effective gauge theories to an arbitrary representation of the SU(2) symmetry
group. Our main focus are fractional topological insulators with time-reversal
symmetry, which are treated as generalizations of the SU(2) quantum Hall
effect.Comment: 8 pages, published versio
(Non)renormalizability of the D-deformed Wess-Zumino model
We continue the analysis of the -deformed Wess-Zumino model which was
started in the previous paper. The model is defined by a deformation which is
non-hermitian and given in terms of the covariant derivatives . We
calculate one-loop divergences in the two-point, three-point and four-point
Green functions. We find that the divergences in the four-point function cannot
be absorbed and thus our model is not renormalizable. We discuss possibilities
to render the model renormalizable.Comment: 19 pages; version accepted for publication in Phys.Rev.D; new section
with the detailed discussion on renormalizabilty added and a special choice
of coupling constants which renders the model renormalizable analyze
Dirichlet boundary conditions in type IIB superstring theory and fermionic T-duality
In this article we investigate the relation between consequences of Dirichlet
boundary conditions (momenta noncommutativity and parameters of the effective
theory) and background fields of fermionic T-dual theory. We impose Dirichlet
boundary conditions on the endpoints of the open string propagating in
background of type IIB superstring theory with constant background fields. We
showed that on the solution of the boundary conditions the momenta become
noncommutative, while the coordinates commute. Fermionic T-duality is also
introduced and its relation to noncommutativity is considered. We use compact
notation so that type IIB superstring formally gets the form of the bosonic one
with Grassman variables. Then momenta noncommutativity parameters are fermionic
T-dual fields. The effective theory, the initial theory on the solution of
boundary conditions, is bilinear in the effective coordinates, odd under
world-sheet parity transformation. The effective metric is equal to the initial
one and terms with the effective Kalb-Ramond field vanish
Relativistic quantum mechanics and the Bohmian interpretation
Conventional relativistic quantum mechanics, based on the Klein-Gordon
equation, does not possess a natural probabilistic interpretation in
configuration space. The Bohmian interpretation, in which probabilities play a
secondary role, provides a viable interpretation of relativistic quantum
mechanics. We formulate the Bohmian interpretation of many-particle wave
functions in a Lorentz-covariant way. In contrast with the nonrelativistic
case, the relativistic Bohmian interpretation may lead to measurable
predictions on particle positions even when the conventional interpretation
does not lead to such predictions.Comment: 10 pages, revised, to appear in Found. Phys. Let
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