GENERALIZED LIE TRANSPORTED STRING IN T-FOLD WITH GENERALIZED KILLING VECTOR

2013 ◽  
Vol 21 ◽  
pp. 169-170 ◽  
Author(s):  
TORU KIKUCHI ◽  
TAKASHI OKADA ◽  
YUHO SAKATANI
Keyword(s):  
String Theory ◽  
Charge Density ◽  
Killing Vector ◽  
String Solution ◽  
Fundamental String ◽  
Density Vector

After constructing the [Formula: see text]-brane background, which is a T-fold in string theory, from a D7-brane via U-duality, we derived the fundamental string solution rotating around it. Reflecting that the [Formula: see text] background is not axisymmetric, the string solution also changes its shape during its rotation. However, we found that the [Formula: see text] background is indeed axisymmetric in the sense of doubled geometry, by explicitly finding a generalized Killing vector. Moreover, the string charge density vector is found to be generalized Lie transported along the generalized Killing vector.

scholarly journals Cosmic strings and superstrings

2010 ◽  
Vol 466 (2115) ◽  
pp. 623-657 ◽  
Author(s):  
Edmund J. Copeland ◽  
T. W. B. Kibble
Keyword(s):  
Field Theory ◽  
String Theory ◽  
Symmetry Breaking ◽  
Cosmic Strings ◽  
Grand Unification ◽  
Brane Inflation ◽  
Fundamental String ◽  
History Of ◽  
M Theory ◽  
The Universe

Cosmic strings are predicted by many field-theory models, and may have been formed at a symmetry-breaking transition early in the history of the universe, such as that associated with grand unification. They could have important cosmological effects. Scenarios suggested by fundamental string theory or M-theory, in particular the popular idea of brane inflation, also strongly suggest the appearance of similar structures. Here we review the reasons for postulating the existence of cosmic strings or superstrings, the various possible ways in which they might be detected observationally and the special features that might discriminate between ordinary cosmic strings and superstrings.

scholarly journals HADRONIC STRING, CONFORMAL INVARIANCE AND CHIRAL SYMMETRY

2003 ◽  
Vol 18 (14) ◽  
pp. 2501-2539 ◽  
Author(s):  
J. ALFARO ◽  
L. BALART ◽  
A. A. ANDRIANOV ◽  
D. ESPRIU
Keyword(s):  
String Theory ◽  
Sigma Model ◽  
Conformal Anomaly ◽  
Nonlinear Sigma Model ◽  
Leading Order ◽  
Qcd Vacuum ◽  
Fundamental String ◽  
Supersymmetric Version ◽  
Long Time ◽  
Model Approach

While it is clear that in some kinematic regime QCD can be described by an effective (as opposed to fundamental) string theory, it is not at all clear how this string theory should be. The "natural" candidate, the bosonic string, leads to amplitudes with the usual problems related to the existence of the tachyon, the absence of the adequate Adler zero, and massless vector particles, not to mention the conformal anomaly. The supersymmetric version does not really solve most of these problems. For a long time it has been believed that the solution of at least some of these difficulties is associated to a proper identification of the vacuum, but this program has remained elusive. We show in this work how the first three problems can be avoided, by using a sigma model approach where excitations above the correct (chirally noninvariant) QCD vacuum are identified. At the leading order in a derivative expansion we recover the nonlinear sigma model of pion interactions. At the next-to-leading order the O(p4) Lagrangian of Gasser and Leutwyler is obtained, with values for the coefficients that match the observed values. We also discuss some issues related to the conformal anomaly.

ON THE DECAY AND EMISSION OF HEAVY FUNDAMENTAL STRINGS

2014 ◽  
Vol 29 (03n04) ◽  
pp. 1430002
Author(s):  
SHOICHI KAWAMOTO
Keyword(s):  
Black Hole ◽  
String Theory ◽  
Thermal Radiation ◽  
Emission Spectrum ◽  
Decay Rate ◽  
Excited States ◽  
Decay Process ◽  
Fundamental String

We review the properties of highly excited states in string theory with a focus on the decay process. We first survey the decay of a fundamental string with various setups. We then discuss the decay rate of averaged excited states of superstrings and obtain the emission spectrum which takes a form of thermal radiation. We finally examine the emission spectrum in the context of the black hole/string correspondence à la Susskind.

scholarly journals COSMOLOGICAL EVOLUTION IN A TYPE-0 STRING THEORY

2002 ◽  
Vol 17 (17) ◽  
pp. 2241-2265 ◽  
Author(s):  
G. A. DIAMANDIS ◽  
B. C. GEORGALAS ◽  
N. E. MAVROMATOS ◽  
E. PAPANTONOPOULOS ◽  
I. PAPPA
Keyword(s):  
String Theory ◽  
Big Bang ◽  
Cosmological Evolution ◽  
Time Dependent ◽  
String Solution ◽  
Brane Worlds ◽  
Fifth Dimension ◽  
Inflationary Phase ◽  
The Universe

We study the cosmological evolution of a type-0 string theory by employing non-criticality, which may be induced by fluctuations of the D3 brane worlds. We check the consistency of the approach to [Formula: see text] in the corresponding σ-model. The ten-dimensional theory is reduced to an effective four-dimensional model, with only time dependent fields. We show that the four-dimensional universe has an inflationary phase and graceful exit from it, while the other extra dimensions are stabilized to a constant value, with the fifth dimension much larger than the others. We pay particular attention to demonstrating the role of tachyonic matter in inducing these features. The universe asymptotes, for large times, to a nonaccelerating linearly-expanding universe with a time-dependent dilaton and a relaxing to zero vacuum energy a lá quintessence. Our perturbative string solution appears to have initial singularities (Big Bang type), which however, we believe, may be lifted in a nonperturbative way, and they do not represent true singularities of the string theory.

Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system

1992 ◽  
Vol 50 (1) ◽  
pp. 58-59
Author(s):  
S. Ritchie ◽  
J. C. Bennett ◽  
A. Prodan ◽  
F.W. Boswell ◽  
J.M. Corbett
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Direct Evidence ◽  
Density Wave ◽  
Wave System ◽  
Modulated Phases ◽  
Metal Atoms ◽  
Incommensurate Modulation ◽  
End Members ◽  
Modulation Wave Vector

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.

A Mathematical Introduction to String Theory

1997 ◽  
Author(s):  
Sergio Albeverio ◽  
Jurgen Jost ◽  
Sylvie Paycha ◽  
Sergio Scarlatti
Keyword(s):  
String Theory
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