scholarly journals Quantum effects in topological and Schwarzschild de Sitter brane: Aspects of torsion on $(D\!{\bar D})_4$-brane

2015 ◽  
Vol 24 (02) ◽  
pp. 1550015 ◽  
Author(s):  
Richa Kapoor ◽  
Supriya Kar ◽  
Deobrat Singh
Keyword(s):  
Gauge Theory ◽  
Quantum Effects ◽  
Open String ◽  
Momentum Tensor ◽  
Closed String ◽  
Low Energy ◽  
De Sitter ◽  
World Volume ◽  
Einstein Vacuum ◽  
Superstring Theories

We investigate an effective torsion curvature in a second-order formalism underlying a two-form world-volume dynamics in a D5-brane. In particular, we consider the two form in presence of a background (open string) metric in a U(1) gauge theory. Interestingly the formalism may be viewed via a noncoincident pair of [Formula: see text]-brane with a global Nereu–Schwarz (NS) two form on an anti-brane and a local two form on a brane. The energy–momentum tensor is computed in the six-dimensional (6D) conformal field theory (CFT). It is shown to source a metric fluctuation on a vacuum created pair of [Formula: see text]-brane at a cosmological horizon by the two-form quanta in the gauge theory. The emergent gravity scenario is shown to describe a low-energy (perturbative) string vacuum in 6D with a nonperturbative (NP) quantum correction by a lower (p < 5) dimensional Dp-brane or an anti-brane in the formalism. A closed string exchange between a pair of [Formula: see text]-brane, underlying a closed/open string duality, is argued to describe the Einstein vacuum in a low-energy limit. We obtain topological de Sitter (TdS) and Schwarzschild brane universe in six dimensions. The brane/anti-brane geometries are analyzed to explore some of their characteristic and thermal behaviors in presence of the quantum effects. They reveal an underlying nine-dimensional type IIA and IIB superstring theories on S1.

Relativistic charged sphere in f(G,T) gravity

2021 ◽  
pp. 2150152
Author(s):  
M. Ilyas ◽  
A. R. Athar ◽  
Bilal Masud
Keyword(s):  
Observational Data ◽  
Density Profile ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Low Energy ◽  
Charged Sphere ◽  
Energy Limit ◽  
Modified Formula ◽  
Superstring Theories ◽  
Charged Spheres

This study explores the interior geometry of static relativistic charged spheres in the background of a recently proposed modified [Formula: see text] gravity, where [Formula: see text] and [Formula: see text] are the Gauss–Bonnet (GB) invariant and trace of energy–momentum tensor, respectively. The GB gravity is the low-energy limit of superstring theories. The structures of specific relativistic charged spheres Vela [Formula: see text], [Formula: see text], and [Formula: see text] are studied in this theory of gravity. We analyzed several physical behaviors of these relativistic charged spheres with the help of observational data and investigated the various aspects like density profile, stresses, the distribution of charges, stability, etc.

scholarly journals 1+1 DIMENSIONAL NCOS AND ITS U(N) GAUGE THEORY DUAL

2001 ◽  
Vol 16 (05) ◽  
pp. 922-935 ◽  
Author(s):  
IGOR R. KLEBANOV ◽  
JUAN MALDACENA
Keyword(s):  
Gauge Theory ◽  
Electric Field ◽  
Electric Fields ◽  
Degrees Of Freedom ◽  
Finite Energy ◽  
Open String ◽  
Closed String ◽  
Dual Theory ◽  
Open Strings ◽  
Electric Flux

We study some aspects of open string theories on D-branes with critical electric fields. We show that the massless open string modes that move in the direction of the electric field decouple. In the 1+1 dimensional case the dual theory is U(N) SYM with electric flux, and the decoupling of massless open strings is dual to the decoupling of the U(1) degrees of freedom. We also show that, if the direction along the electric field is compact, then there are finite energy winding closed string modes. They are dual to Higgs branch excitations of the SYM theory, and their energetics works accordingly. These properties provide new non-trivial evidence for the duality.

scholarly journals QUANTUM DESCRIPTION FOR THE DECAY OF NSNS BRANE–ANTIBRANE SYSTEMS

2004 ◽  
Vol 19 (28) ◽  
pp. 4861-4882
Author(s):  
HONGSU KIM
Keyword(s):  
Gauge Theory ◽  
Tachyon Condensation ◽  
Open String ◽  
Quantum Description ◽  
World Volume ◽  
Poor Understanding ◽  
String Dualities ◽  
Quantum Interpretation ◽  
M Theory

The stringy description for the instabilities in the RR charged [Formula: see text] pairs is now well understood in terms of the open string tachyon condensation. The quantum interpretation presumably via the stringy description for the instabilities in the NSNS-charged [Formula: see text] and [Formula: see text] pairs in IIA/IIB theories, however, has not been fully established yet. This would be partly because of the absence (for the [Formula: see text] case) or our relatively poor understanding (for the [Formula: see text] case) of their world-volume (gauge theory) dynamics. In the present work, using the well-known quantum description for instabilities in the RR-charged [Formula: see text] systems and in the M-theory brane–antibrane systems and invoking appropriate string dualities, the stringy nature of the instabilities in the NSNS-charged [Formula: see text] and [Formula: see text] systems both at strong and at weak couplings has been uncovered. For the annihilations to string vacua, the quantum, stringy interpretations are simple extensions of Sen's conjecture for those in RR-charged brane–antibrane systems.

scholarly journals Extracting bigravity from string theory

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Dieter Lüst ◽  
Chrysoula Markou ◽  
Pouria Mazloumi ◽  
Stephan Stieberger
Keyword(s):  
Scattering Amplitudes ◽  
String Theory ◽  
Open String ◽  
Closed String ◽  
Bimetric Theory ◽  
Low Energy ◽  
Tree Level ◽  
Dark Matter Candidate ◽  
Massive Spin ◽  
Numerical Coefficient

Abstract The origin of the graviton from string theory is well understood: it corresponds to a massless state in closed string spectra, whose low-energy effective action, as extracted from string scattering amplitudes, is that of Einstein-Hilbert. In this work, we explore the possibility of such a string-theoretic emergence of ghost-free bimetric theory, a recently proposed theory that involves two dynamical metrics, that around particular backgrounds propagates the graviton and a massive spin-2 field, which has been argued to be a viable dark matter candidate. By choosing to identify the latter with a massive spin-2 state of open string spectra, we compute tree-level three-point string scattering amplitudes that describe interactions of the massive spin-2 with itself and with the graviton. With the mass of the external legs depending on the string scale, we discover that extracting the corresponding low-energy effective actions in four spacetime dimensions is a subtle but consistent process and proceed to appropriately compare them with bimetric theory. Our findings consist in establishing that string and bimetric theory provide to lowest order the same set of two-derivative terms describing the interactions of the massive spin-2 with itself and with the graviton, albeit up to numerical coefficient discrepancies, a fact that we analyze and interpret. We conclude with a mention of future investigations.

scholarly journals A NOTE ON NONCOMMUTATIVE STRING THEORY AND ITS LOW ENERGY LIMIT

2003 ◽  
Vol 18 (10) ◽  
pp. 1733-1747
Author(s):  
SHESANSU SEKHAR PAL
Keyword(s):  
Gauge Theory ◽  
Scattering Amplitudes ◽  
String Theory ◽  
Open String ◽  
Low Energy ◽  
Energy Limit ◽  
Noncommutative Gauge Theory

The noncommutative string theory is described by embedding open string theory in a constant second rank antisymmetric Bμν field and the noncommutative gauge theory is defined by a deformed ⋆ product. As a check, the study of various scattering amplitudes in both noncommutative string and noncommutative gauge theory confirms that in the α′ → 0 limit, the noncommutative string theoretic amplitude goes over to the noncommutative gauge theoretic amplitude and the couplings are related as [Formula: see text]. Furthermore, we show that in this limit there will not be any correction to the gauge theoretic action because of the absence of massive modes. We get sin/cos factors in the scattering amplitudes depending on the odd/even number of external photons.

scholarly journals $$\mathbf {O}(D,D)$$ completion of the Friedmann equations

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Stephen Angus ◽  
Kyoungho Cho ◽  
Guilherme Franzmann ◽  
Shinji Mukohyama ◽  
Jeong-Hyuck Park
Keyword(s):  
General Relativity ◽  
Momentum Tensor ◽  
Closed String ◽  
Matter Content ◽  
Positive Energy ◽  
De Sitter ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Generalized Continuity ◽  
Friedmann Equations

AbstractIn string theory the closed-string massless NS-NS sector forms a multiplet of $$\mathbf {O}(D,D)$$ O ( D , D ) symmetry. This suggests a specific modification to General Relativity in which the entire NS-NS sector is promoted to stringy graviton fields. Imposing off-shell $$\mathbf {O}(D,D)$$ O ( D , D ) symmetry fixes the correct couplings to other matter fields and the Einstein field equations are enriched to comprise $$D^{2}+1$$ D 2 + 1 components, dubbed recently as the Einstein Double Field Equations. Here we explore the cosmological implications of this framework. We derive the most general homogeneous and isotropic ansatzes for both stringy graviton fields and the $$\mathbf {O}(D,D)$$ O ( D , D ) -covariant energy-momentum tensor. Crucially, the former admits space-filling magnetic H-flux. Substituting them into the Einstein Double Field Equations, we obtain the $$\mathbf {O}(D,D)$$ O ( D , D ) completion of the Friedmann equations along with a generalized continuity equation. We discuss how solutions in this framework may be characterized by two equation-of-state parameters, w and $$\lambda $$ λ , where the latter characterizes the relative intensities of scalar and tensor forces. When $$\lambda +3w=1$$ λ + 3 w = 1 , the dilaton remains constant throughout the cosmological evolution, and one recovers the standard Friedmann equations for generic matter content (i.e. for any w). We further point out that, in contrast to General Relativity, neither an $$\mathbf {O}(D,D)$$ O ( D , D ) -symmetric cosmological constant nor a scalar field with positive energy density gives rise to a de Sitter solution.

scholarly journals OPEN STRINGS AND NONCOMMUTATIVE GEOMETRY OF BRANES ON GROUP MANIFOLDS

2001 ◽  
Vol 16 (04n06) ◽  
pp. 325-335 ◽  
Author(s):  
VOLKER SCHOMERUS ◽  
ANTON YU. ALEKSEEV ◽  
ANDREAS RECKNAGEL
Keyword(s):  
Recent Work ◽  
Noncommutative Geometry ◽  
Effective Action ◽  
Open String ◽  
Low Energy ◽  
Yang Mills ◽  
Open Strings ◽  
World Volume ◽  
Chern Simons

In this letter we review some recent work on the noncommutative geometry of branes on group manifolds. In particular, we show how fuzzy spaces arise in this context from an exact worldsheet description and we sketch the construction of a low-energy effective action for massless open string modes. The latter is given by a combination of a Yang–Mills and a Chern–Simons like functional on the fuzzy world-volume. It can be used to study condensation on various brane configurations in curved backgrounds.

scholarly journals Non-supersymmetric string models from anti-D3-/D7-branes in strongly warped throats

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Susha Parameswaran ◽  
Flavio Tonioni
Keyword(s):  
Model Building ◽  
Open String ◽  
Closed String ◽  
Effective Field ◽  
De Sitter ◽  
Supergravity Theory ◽  
Particle Spectra ◽  
Soft Supersymmetry Breaking ◽  
String Models ◽  
Matter Sector

Abstract This article discusses model-building scenarios including anti-D3-/D7-branes, in which supersymmetry is broken spontaneously, despite having no scale at which sparticles appear and standard supersymmetry is restored. If the branes are placed on singularities at the tip of warped throats in Calabi-Yau orientifold flux compactifications, they may give rise to realistic particle spectra, closed- and open-string moduli stabilisation with a Minkowski/de Sitter uplift, and a geometrical origin for the scale hierarchies. The paper derives the low-energy effective field theory description for such scenarios, i.e. a non-linear supergravity theory for standard and constrained supermultiplets, including soft supersymmetry-breaking matter couplings. The effect of closed-string moduli stabilisation on the open-string matter sector is worked out, incorporating non-perturbative and perturbative effects, and the mass and coupling hierarchies are computed with a view towards phenomenology.

Quantum effects in low-energy photofission of heavy nuclei

1984 ◽  
Vol 144 (9) ◽  
pp. 3 ◽  
Author(s):  
Yurii M. Tsipenyuk ◽  
Yu.B. Ostapenko ◽  
G.N. Smirenkin ◽  
A.S. Soldatov
Keyword(s):  
Quantum Effects ◽  
Low Energy ◽  
Heavy Nuclei

scholarly journals On the quantization of folded strings in non-critical dimensions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Jacob Sonnenschein ◽  
Dorin Weissman
Keyword(s):  
Scalar Curvature ◽  
Space Dimension ◽  
Massive Particle ◽  
Open String ◽  
Closed String ◽  
Target Space ◽  
Critical Dimensions ◽  
Complete Set ◽  
Rotating String ◽  
Folding Point

Abstract Classical rotating closed string are folded strings. At the folding points the scalar curvature associated with the induced metric diverges. As a consequence one cannot properly quantize the fluctuations around the classical solution since there is no complete set of normalizable eigenmodes. Furthermore in the non-critical effective string action of Polchinski and Strominger, there is a divergence associated with the folds. We overcome this obstacle by putting a massive particle at each folding point which can be used as a regulator. Using this method we compute the spectrum of quantum fluctuations around the rotating string and the intercept of the leading Regge trajectory. The results we find are that the intercepts are a = 1 and a = 2 for the open and closed string respectively, independent of the target space dimension. We argue that in generic theories with an effective string description, one can expect corrections from finite masses associated with either the endpoints of an open string or the folding points on a closed string. We compute explicitly the corrections in the presence of these masses.

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