4,697 research outputs found

### Heterotic String Models in Curved Spacetime

We explore the possibility of string theories in only four spacetime
dimensions without any additional compactified dimensions. We show that,
provided the theory is defined in curved spacetime that has a cosmological
interpration, it is possible to construct consistent heterotic string theories
based on a few non-compact current algebra cosets. We classify these models.
The gauge groups that emerge fall within a remarkably narrow range and include
the desirable low energy flavor symmetry of $SU(3)\times SU(2)\times U(1)$. The
quark and lepton states, which come in color triplets and $SU(2)$ doublets, are
expected to emerge in several families.Comment: USC-92/HEP-B4, 10 page

### Hidden 12-dimensional structures in AdS(5)xS(5) and M(4)xR(6) Supergravities

It is shown that AdS(5)xS(5) supergravity has hitherto unnoticed
supersymmetric properties that are related to a hidden 12-dimensional
structure. The totality of the AdS(5)xS(5) supergravity Kaluza-Klein towers is
given by a single superfield that describes the quantum states of a
12-dimensional supersymmetric particle. The particle has super phase space
(X,P,Theta) with (10,2) signature and 32 fermions. The worldline action is
constructed as a generalization of the supersymmetric particle action in
Two-Time Physics. SU(2,2|4) is a linearly realized global supersymmetry of the
2T action. The action is invariant under the gauge symmetries Sp(2,R),
SO(4,2),SO(6), and fermionic kappa. These gauge symmetries insure unitarity and
causality while allowing the reduction of the 12-dimensional super phase space
to the correct super phase space for AdS(5)xS(5) or M(4)xR(6) with 16 fermions
and one time, or other dually related one time spaces. One of the predictions
of this formulation is that all of the SU(2,2|4) representations that describe
Kaluza-Klein towers in AdS(5)xS(5) or M(4)xR(6) supergravity universally have
vanishing eigenvalues for all the Casimir operators. This prediction has been
verified directly in AdS(5)xS(5) supergravity. This suggests that the
supergravity spectrum supports a hidden (10,2) structure. A possible duality
between AdS(5)xS(5) and M(4)xR(6) supergravities is also indicated.
Generalizations of the approach applicable 10-dimensional super Yang Mills
theory and 11-dimensional M-theory are briefly discussed.Comment: LaTeX, 32 pages. v2 includes additional generalizations in the
discussion section. The norm of J has been modified in eqs.(2.6, 3.3, 3.8).
v3 includes a correction to Eq.(5.3

### A case for 14 dimensions

Extended superalgebras of types A,B,C, heterotic and type-I are all derived
as solutions to a BPS equation in 14 dimensions with signature ( 11,3). The BPS
equation as well as the solutions are covariant under SO( 11,3). This shows how
supersymmetries with N<=8 in four dimensions have their origin in the same
superalgebra in 14D. The solutions provide different bases for the same
superalgebra in 4D, and the transformations among bases correspond to various
dualities.Comment: Latex, 14 page

### Interacting Two-Time Physics Field Theory With a BRST Gauge Invariant Action

We construct a field theoretic version of 2T-physics including interactions
in an action formalism. The approach is a BRST formulation based on the
underlying Sp(2,R)gauge symmetry, and shares some similarities with the
approach used to construct string field theory. In our first case of spinless
particles, the interaction is uniquely determined by the BRST gauge symmetry,
and it is different than the Chern-Simons type theory used in open string field
theory. After constructing a BRST gauge invariant action for 2T-physics field
theory with interactions in d+2 dimensions, we study its relation to standard
1T-physics field theory in (d-1)+1 dimensions by choosing gauges. In one gauge
we show that we obtain the Klein-Gordon field theory in (d-1)+1 dimensions with
unique SO(d,2) conformal invariant self interactions at the classical field
level. This SO(d,2) is the natural linear Lorentz symmetry of the 2T field
theory in d+2 dimensions. As indicated in Fig.1, in other gauges we expect to
derive a variety of SO(d,2)invariant 1T-physics field theories as gauge fixed
forms of the same 2T field theory, thus obtaining a unification of 1T-dynamics
in a field theoretic setting, including interactions. The BRST gauge
transformation should play the role of duality transformations among the
1T-physics holographic images of the same parent 2T field theory. The
availability of a field theory action opens the way for studying 2T-physics
with interactions at the quantum level through the path integral approach.Comment: 22 pages, 1 figure, v3 includes corrections of typos and some
comment

### Gravity in 2T-Physics

The field theoretic action for gravitational interactions in d+2 dimensions
is constructed in the formalism of 2T-physics. General Relativity in d
dimensions emerges as a shadow of this theory with one less time and one less
space dimensions. The gravitational constant turns out to be a shadow of a
dilaton field in d+2 dimensions that appears as a constant to observers stuck
in d dimensions. If elementary scalar fields play a role in the fundamental
theory (such as Higgs fields in the Standard Model coupled to gravity), then
their shadows in d dimensions must necessarily be conformal scalars. This has
the physical consequence that the gravitational constant changes at each phase
transition (inflation, grand unification, electro-weak, etc.), implying
interesting new scenarios in cosmological applications. The fundamental action
for pure gravity, which includes the spacetime metric, the dilaton and an
additional auxiliary scalar field all in d+2 dimensions with two times, has a
mix of gauge symmetries to produce appropriate constraints that remove all
ghosts or redundant degrees of freedom. The action produces on-shell classical
field equations of motion in d+2 dimensions, with enough constraints for the
theory to be in agreement with classical General Relativity in d dimensions.
Therefore this action describes the correct classical gravitational physics
directly in d+2 dimensions. Taken together with previous similar work on the
Standard Model of particles and forces, the present paper shows that 2T-physics
is a general consistent framework for a physical theory.Comment: 24 pages, revision includes minor corrections and additional
clarifying materia

### Dualities among 1T-Field Theories with Spin, Emerging from a Unifying 2T-Field Theory

The relation between two time physics (2T-physics) and the ordinary one time
formulation of physics (1T-physics) is similar to the relation between a
3-dimensional object moving in a room and its multiple shadows moving on walls
when projected from different perspectives. The multiple shadows as seen by
observers stuck on the wall are analogous to the effects of the 2T-universe as
experienced in ordinary 1T spacetime. In this paper we develop some of the
quantitative aspects of this 2T to 1T relationship in the context of field
theory. We discuss 2T field theory in d+2 dimensions and its shadows in the
form of 1T field theories when the theory contains Klein-Gordon, Dirac and
Yang-Mills fields, such as the Standard Model of particles and forces. We show
that the shadow 1T field theories must have hidden relations among themselves.
These relations take the form of dualities and hidden spacetime symmetries. A
subset of the shadows are 1T field theories in different gravitational
backgrounds (different space-times) such as the flat Minkowski spacetime, the
Robertson-Walker expanding universe, AdS(d-k) x S(k) and others, including
singular ones. We explicitly construct the duality transformations among this
conformally flat subset, and build the generators of their hidden SO(d,2)
symmetry. The existence of such hidden relations among 1T field theories, which
can be tested by both theory and experiment in 1T-physics, is part of the
evidence for the underlying d+2 dimensional spacetime and the unifying
2T-physics structure.Comment: 33 pages, LaTe

### Super Yang-Mills in (11,3) Dimensions

A supersymmetric Yang-Mills system in (11,3) dimensions is constructed with
the aid of two mutually orthogonal null vectors which naturally arise in a
generalized spacetime superalgebra. An obstacle encountered in an attempt to
extend this result to beyond 14 dimensions is described. A null reduction of
the (11,3) model is shown to yield the known super Yang-Mills model in (10,2)
dimensions. An (8,8) supersymmetric super Yang-Mills system in (3,3) dimensions
is obtained by an ordinary dimensional reduction of the (11,3) model, and it is
suggested there may exist a superbrane with (3,3) dimensional worldvolume
propagating in (11,3) dimensions.Comment: 13 pages, late

### Superstrings with new supersymmetry in (9,2) and (10,2) dimensions

We construct superstring theories that obey the new supersymmetry algebra
{Q_a , Q_b}=\gamma_{ab}^{mn} P_{1m} P_{2n}, in a Green-Schwarz formalism, with
kappa supersymmetry also of the new type. The superstring is in a system with a
superparticle so that their total momenta are $P_{2n},P_{1m}$ respectively. The
system is covariant and critical in (10,2) dimensions if the particle is
massless and in (9,2) dimensions if the particle is massive. Both the
superstring and superparticle have coordinates with two timelike dimensions but
each behaves effectively as if they have a single timelike dimension. This is
due to gauge symmetries and associated constraints. We show how to generalize
the gauge principle to more intricate systems containing two parts, 1 and 2.
Each part contains interacting constituents, such as p-branes, and each part
behaves effectively as if they have one timelike coordinate, although the full
system has two timelike coordinates. The examples of two superparticles, and of
a superparticle and a superstring, discussed in more detail are a special cases
of such a generalized interacting system.Comment: LaTeX, revtex, 9 page

### Hidden Symmetries, AdS_D x S^n, and the lifting of one-time-physics to two-time-physics

The massive non-relativistic free particle in d-1 space dimensions has an
action with a surprizing non-linearly realized SO(d,2) symmetry. This is the
simplest example of a host of diverse one-time-physics systems with hidden
SO(d,2) symmetric actions. By the addition of gauge degrees of freedom, they
can all be lifted to the same SO(d,2) covariant unified theory that includes an
extra spacelike and an extra timelike dimension. The resulting action in d+2
dimensions has manifest SO(d,2) Lorentz symmetry and a gauge symmetry Sp(2,R)
and it defines two-time-physics. Conversely, the two-time action can be gauge
fixed to diverse one-time physical systems. In this paper three new gauge fixed
forms that correspond to the non-relativistic particle, the massive
relativistic particle, and the particle in AdS_(d-n) x S^n spacetime will be
discussed. The last case is discussed at the first quantized and field theory
levels as well. For the last case the popularly known symmetry is SO(d-n-1,2) x
SO(n+1), but yet we show that it is symmetric under the larger SO(d,2). In the
field theory version the action is symmetric under the full SO(d,2) provided it
is improved with a quantized mass term that arises as an anomaly from operator
ordering ambiguities. The anomalous cosmological term vanishes for AdS_2 x S^0
and AdS_n x S^n (i.e. d=2n). The strikingly larger symmetry could be
significant in the context of the proposed AdS/CFT duality.Comment: Latex, 23 pages. The term "cosmological constant" that appeared in
the original version has been changed to "mass term". My apologies for the
confusio

### Gauge symmetry in phase space with spin, a basis for conformal symmetry and duality among many interactions

We show that a simple OSp(1/2) worldline gauge theory in 0-brane phase space
(X,P), with spin degrees of freedom, formulated for a d+2 dimensional spacetime
with two times X^0,, X^0', unifies many physical systems which ordinarily are
described by a 1-time formulation. Different systems of 1-time physics emerge
by choosing gauges that embed ordinary time in d+2 dimensions in different
ways. The embeddings have different topology and geometry for the choice of
time among the d+2 dimensions. Thus, 2-time physics unifies an infinite number
of 1-time physical interacting systems, and establishes a kind of duality among
them. One manifestation of the two times is that all of these physical systems
have the same quantum Hilbert space in the form of a unique representation of
SO(d,2) with the same Casimir eigenvalues. By changing the number n of spinning
degrees of freedom the gauge group changes to OSp(n/2). Then the eigenvalue of
the Casimirs of SO(d,2) depend on n and then the content of the 1-time physical
systems that are unified in the same representation depend on n. The models we
study raise new questions about the nature of spacetime.Comment: Latex, 42 pages. v2 improvements in AdS section. In v3 sec.6.2 is
modified; the more general potential is limited to a smaller clas

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