共查询到20条相似文献,搜索用时 31 毫秒
1.
J. Klusoň Kamal L. Panigrahi 《The European Physical Journal C - Particles and Fields》2011,71(3):1595
We continue our study of the Lorentz-breaking string theories. These theories are defined as string theory with modified Hamiltonian
constraint which breaks the Lorentz symmetry of target space-time. We analyze the properties of this theory in the target
space-time that possesses isometry along one direction. We also derive the T-duality rules for Lorentz-breaking string theories
and show that they are the same as that of Buscher’s T-duality for the relativistic strings. 相似文献
2.
Jacek Gruszczak 《International Journal of Theoretical Physics》2008,47(11):2911-2923
Differential properties of Klein-Gordon and electromagnetic fields on the space-time of a straight cosmic string are studied
with the help of methods of the differential space theory. It is shown that these fields are smooth in the interior of the
cosmic string space-time and that they loose this property at the singular boundary except for the cosmic string space-times
with the following deficit angles: Δ=2π(1−1/n), n=1,2,… .
A connection between smoothness of fields at the conical singularity and the scalar and electromagnetic conical bremsstrahlung
is discussed. It is also argued that the smoothness assumption of fields at the singularity is equivalent to the Aliev and
Gal’tsov “quantization” condition leading to the above mentioned discrete spectrum of the deficit angle. 相似文献
3.
S. N. Vergeles 《Journal of Experimental and Theoretical Physics》1998,86(5):854-859
An anomaly-free quantum theory of a relativistic string is constructed in two-dimensional space-time. The states of the string
are found to be similar to the states of a massless chiral quantum particle. This result is obtained by generalizing the concept
of an “operator” in quantum field theory.
Zh. éksp. Teor. Fiz. 113, 1566–1578 (May 1998) 相似文献
4.
Jen-Chi Lee 《The European Physical Journal C - Particles and Fields》2000,13(4):691-694
We calculate the NS–R fermionic zero-norm states of the type II string spectrum. The massless and some possible massive zero-norm
states are seen to be responsible for the space-time supersymmetry. The existence of other fermionic massive zero-norm states
with higher spinor–tensor indices correspond to new enlarged boson–fermion symmetries of the theory at high energy. We also
discuss the R–R charges and R–R zero-norm states and justify the idea that the perturbative string does not carry the massless
R–R charges.
Received: 12 July 1999 / Revised version: 16 September 1999 / Published online: 17 March 2000 相似文献
5.
《Journal of Geometry and Physics》1995,16(1):15-26
A new approach for investigating the classical dynamics of the relativistic string model with rigidity is proposed. It is based on the embedding of the string world surface into a space of constant curvature. It is shown that the rigid string in flat space-time is described by the Euler-Lagrange equation for the Willmore functional in a space-time of constant curvature K = −γ/(2α), where γ and α are constants in front of the Nambu-Goto term and the curvature term in the rigid string action, respectively. For simplicity the Euclidean version of the rigid string in three-dimensional space-time is considered. The Willmore functional (the action for the “Willmore string”) is obtained by dropping the Nambu-Goto term in the Polyakov-Kleinert action for the rigid string. Such a “reduction” of the rigid string model would be useful, for example, by applying some results about the Nambu-Goto string dynamics in the de Sitter universe to the rigid string model in the Minkowski space-time. It also allows us to use numerous mathematical results about Willmore surfaces in the context of the physical problem. 相似文献
6.
Some cosmological solutions of massive strings are obtained in Bianchi I space-time following the techniques used by Letelier
and Stachel. A class of solutions corresponds to string cosmology associated with/without a magnetic field and the other class
consists of pure massive strings, obeying the Takabayashi equation of stateρ=(1+W)λ. 相似文献
7.
AP Balachandran 《Pramana》2002,59(2):359-368
We review certain emergent notions on the nature of space-time from noncommutative geometry and their radical implications.
These ideas of space-time are suggested from developments in fuzzy physics, string theory, and deformation quantization. The
review focuses on the ideas coming from fuzzy physics. We find models of quantum space-time like fuzzy S
4 on which states cannot be localized, but which fluctuate into other manifolds like CP3. New uncertainty principles concerning such lack of localizability on quantum space-times are formulated. Such investigations
show the possibility of formulating and answering questions like the probability of finding a point of a quantum manifold
in a state localized on another one. Additional striking possibilities indicated by these developments is the (generic) failure
of CPT theorem and the conventional spin-statistics connection. They even suggest that Planck’s ‘constant’ may not be a constant,
but an operator which does not commute with all observables. All these novel possibilities arise within the rules of conventional
quantum physics, and with no serious input from gravity physics. 相似文献
8.
9.
In the present article, we derive the space-time action of the bosonic string in terms of geometrical quantities. First, we
study the space-time geometry felt by a probe bosonic string moving in antisymmetric and dilaton background fields. We show
that the presence of the antisymmetric field leads to space-time torsion, and the presence of the dilaton field leads to space-time
non-metricity. Using these results we obtain the integration measure for space-time with stringy non-metricity, requiring
its preservation under parallel transport. We derive the Lagrangian depending on stringy curvature, torsion and non-metricity. 相似文献
10.
Motivated by the possibility of a finite theory of gravity provided by superstrings in ten space-time dimensions, we analyze the problem of space compactification in the context of string dynamics. Such an analysis is hampered by conceptual and technical problems, stemming from the existence of the quantum string's own graviton mode on the one hand, and from Witten's observation of anomalies in a not specially chosen curves space-time on the other hand. Still, in the context of a classical local field presentation of string theory à la Nambu and Hosotani, supplemented by gravitational and Kalb-Ramond interactions, we are able to find solutions with space compactification. It is the antisymmetric tensor zero modes that dictate this compactification towards three space-time dimensions for ordinary strings or towards four or five space-time dimensions for superstrings. 相似文献
11.
《Physics letters. [Part B]》1986,171(1):51-56
A complete classification is given of all supersymmetric theories of free massless two-dimensional fermions. This, in particular, implies a classification of all free-fermion representations of super Kac-Moody algebras. It is shown that these cannot be used to construct new string theories with unbroken supersymmetry in Minkowski space-time, other than the torus-compactifications of the known ten-dimensional superstrings. Assuming anti-de-Sitter space-time could restore conformal invariance, it is shown how one could construct a string theory whose low-lying excitations form a multiplet of gauged N = 8 supergravity. 相似文献
12.
《Nuclear Physics B》1995,454(3):541-560
We propose a new formulation of the space-time interpretation of the c = 1 matrix model. Our formulation uses the well-known leg-pole factor that relates the matrix model amplitudes to that of the 2-dimensional string theory, but includes fluctuations around the Fermi vacuum on both sides of the inverted harmonic oscillator potential of the double-scaled model, even when the fluctuations are small and confined entirely within the asymptotes in the phase plane. We argue that including fluctuations on both sides of the potential is essential for a consistent interpretation of the leg-pole transformed theory as a theory of space-time gravity. We reproduce the known results for the string theory tree-level scattering amplitudes for flat space and linear dilaton background as a special case. We show that the generic case corresponds to more general space-time backgrounds. In particular, we identify the parameter corresponding to background metric perturbation in string theory (black-hole mass) in terms of the matrix model variables. Possible implications of our work for a consistent non-perturbative definition of string theory as well as for quantized gravity and black-hole physics are discussed. 相似文献
13.
Nick E. Mavromatos 《Foundations of Physics》2010,40(7):917-960
I discuss a model inspired from the string/brane framework, in which our Universe is represented (after perhaps appropriate
compactification) as a three brane, propagating in a bulk space time punctured by D0-brane (D-particle) defects. As the D3-brane
world moves in the bulk, the D-particles cross it, and from an effective observer on D3 the situation looks like a “space-time
foam” with the defects “flashing” on and off (“D-particle foam”). The open strings, with their ends attached on the brane,
which represent matter in this scenario, can interact with the D-particles on the D3-brane universe in a topologically non-trivial
manner, involving splitting and capture of the strings by the D0-brane defects. Such processes are consistently described
by logarithmic conformal field theories on the world-sheet of the strings. Physically, they result in effective decoherence
of the string matter on the D3 brane, and as a result, of CPT Violation, but of a type that implies an ill-defined nature
of the effective CPT operator. Due to electric charge conservation, only electrically neutral (string) matter can exhibit
such interactions with the D-particle foam. This may have unique, experimentally detectable (in principle), consequences for
electrically-neutral entangled quantum matter states on the brane world, in particular the modification of the pertinent Einstein-Podolsky-Rosen
(EPR) Correlation in neutral mesons in an appropriate meson factory. For the simplest scenarios, the order of magnitude of
such effects might lie within the sensitivity of upgraded φ-meson factories. 相似文献
14.
Harald H. Soleng 《General Relativity and Gravitation》1992,24(1):111-117
The Einstein-Cartan field equations are solved for a string source with spin-polarisation along the axis of symmetry. The interior solution is matched to an exterior vacuum space-time using Arkuszewski-Kopczyski-Ponomariev junction conditions. The exterior solution is a four dimensional extension of the space-time outside a spinning point particle in three dimensional Einstein theory. It reduces to the geometry outside a conventional straight cosmic string in the case of vanishing spin. 相似文献
15.
《Physics letters. [Part B]》1988,209(4):477-484
We solve the Einstein-Maxwell and scalar field equations for an infinitely long bosonic superconducting cosmic string and explore the associated geometry of space-time. The metric describing the space-time is valid for both fermionic and bosonic superconducting cosmic strings. Due to general relativistic corrections, the magnetic field energy per unit length associated with the string does not diverge. A non-uniform charged Higgs field contribution to the stress-energy tensor endows the string with an effective mass that enables to attract gravitationally and alters its lensing properties. 相似文献
16.
Alexander Pavlov 《International Journal of Theoretical Physics》1997,36(10):2107-2113
A system with constraints is considered: a string theory whose Lagrangian is thenth power of the Gauss curvature of a space-time manifold (n∈N,n>1). The problem is solved exactly because after the constraints are utilized we deal with a variational problem with a trivial
Lagrangian, i.e., its Euler-Lagrange equations are satisfied identically. One can say that the constraints “swallow” all dynamical
degrees of freedom of the field theory. The investigation is a continuation of the 1989 work of Burlankov and Pavlov, who
solved the problem of two-dimensionalR
2-gravitation under the gauge γ=1. 相似文献
17.
S. N. Solodukhin 《International Journal of Theoretical Physics》1992,31(1):47-57
The string model is formulated in terms of two-dimensional differential forms of arbitrary rank. The local supersymmetric string action with local conformal and Lorentz symmetries is constructed. The connection with topological quantum field theory is discussed. Covariant quantization of the model is investigated. The critical space-time dimension is found to bed=4. 相似文献
18.
Michael Heller Zdzisław Odrzygóźdź Leszek Pysiak Wiesław Sasin 《International Journal of Theoretical Physics》2008,47(10):2566-2575
We study a purely gravitational Aharonov-Bohm effect. The space-time curvature is concentrated in the quasiregular singularity
of a cosmic string, outside of which space-time is (locally) flat. The symmetries of this field configuration are described
by the groupoid symmetries rather than by the usual group symmetries. The groupoid in question is formed by homotopy classes
of piecewise smooth paths in the cosmic string region. A gravitational counterpart of the Aharonov-Bohm effect occurs if the
symmetry of the system, with respect to the groupoid action, is broken down. 相似文献
19.
E. Ahmed E. A. El-Rifai R. A. Abdellatif 《International Journal of Theoretical Physics》1991,30(2):205-209
A ribbon knot can be represented as the propagation of an open string in (Euclidean) space-time. By imposing physical conditions plus an ansatz on the string scattering amplitude, we get invariant polynomials of ribbon knots which correspond to Jones and Wadatiet al. polynomials for ordinary knots. Motivated by the string scattering vertices, we derive an algebra which is a generalization of Hecke and Murakami-Birman-Wenzel (BMW) algebras of knots. 相似文献
20.
By analyzing a gedanken experiment designed to measure the distance l between two spatially separated points, we find that this distance cannot be measured with uncertainty less than (ll
2
P)
1/3
, considerably larger than the Planck scale lP (or the string scale in string theories), the conventional-wisdom uncertainty in distance measurements. This limitation to space-time measurements is interpreted as resulting from quantum fluctuations of space-time itself. Thus, at very short distance scales, space-time is foamy. This intrinsic foaminess of space-time provides another source of noise in the interferometers. The LIGO/VIRGO and LISA generations of gravity-wave interferometers, through future refinements, are expected to reach displacement noise levels low enough to test our proposed degree of foaminess in the structure of space-time. 相似文献