scholarly journals ON THE EVALUATION OF COMPTON SCATTERING AMPLITUDES IN STRING THEORY

1998 ◽  
Vol 13 (27) ◽  
pp. 4717-4757 ◽  
Author(s):  
ANDREA PASQUINUCCI ◽  
MICHELA PETRINI
Keyword(s):  
Scattering Amplitudes ◽  
String Theory ◽  
Moduli Space ◽  
Modular Forms ◽  
String Model ◽  
World Sheet ◽  
Electron Positron ◽  
The World ◽  
Spin Fields ◽  
Compton Amplitude

We consider the Compton amplitude for the scattering of a photon and an (massless) "electron/positron" at one loop (i.e. genus 1) in a four-dimensional fermionic heterotic string model. Starting from the bosonization of the world sheet fermions needed to explicitly construct the spin fields representing the space–time fermions, we present all the steps of the computation which leads to the explicit form of the amplitude as an integral of modular forms over the moduli space.

scholarly journals STRINGS, NONCOMMUTATIVE GEOMETRY AND THE SIZE OF THE TARGET SPACE

1999 ◽  
Vol 14 (28) ◽  
pp. 4501-4517 ◽  
Author(s):  
FEDELE LIZZI
Keyword(s):  
String Theory ◽  
Dirac Operator ◽  
Noncommutative Geometry ◽  
Low Energy ◽  
Target Space ◽  
World Sheet ◽  
Crucial Point ◽  
Spectral Action ◽  
Energy Eigenvalues ◽  
The World

We describe how the presence of the antisymmetric tensor (torsion) on the world sheet action of string theory renders the size of the target space a gauge noninvariant quantity. This generalizes the R ↔ 1/R symmetry in which momenta and windings are exchanged, to the whole O(d,d,ℤ). The crucial point is that, with a transformation, it is possible always to have all of the lowest eigenvalues of the Hamiltonian to be momentum modes. We interpret this in the framework of noncommutative geometry, in which algebras take the place of point spaces, and of the spectral action principle for which the eigenvalues of the Dirac operator are the fundamental objects, out of which the theory is constructed. A quantum observer, in the presence of many low energy eigenvalues of the Dirac operator (and hence of the Hamiltonian) will always interpreted the target space of the string theory as effectively uncompactified.

scholarly journals ON HIGHER-SPIN GENERALIZATIONS OF STRING THEORY

1994 ◽  
Vol 09 (09) ◽  
pp. 1527-1543 ◽  
Author(s):  
H. LU ◽  
C. N. POPE ◽  
X. J. WANG
Keyword(s):  
String Theory ◽  
Gauge Field ◽  
Virasoro Algebra ◽  
Two Dimensional ◽  
Minimal Models ◽  
World Sheet ◽  
The World ◽  
Higher Spin ◽  
String Theories

We construct BRST operators for certain higher-spin extensions of the Virasoro algebra, in which there is a spin-s gauge field on the world sheet, as well as the spin-2 gauge field corrresponding to the two-dimensional metric. We use these BRST operators to study the physical states of the associated string theories, and show how they are related to certain minimal models.

VORTICES IN HIGH-TEMPERATURE STRING THEORY

1989 ◽  
Vol 04 (11) ◽  
pp. 1063-1067 ◽  
Author(s):  
G. CHAPLINE ◽  
F.R. KLINKHAMER
Keyword(s):  
Phase Transition ◽  
Free Energy ◽  
High Temperature ◽  
String Theory ◽  
High Temperatures ◽  
World Sheet ◽  
Genus Zero ◽  
Mass Gap ◽  
The World

We discuss the role of XY-like vortices on the world-sheet for the free energy of strings at high temperatures. There is a Kosterlitz-Thouless phase transition at the Hagedorn temperature, above which the vortices contribute to the free energy in genus zero and generate a mass gap. We speculate that high-temperature “string” theory could be essentially discrete.

scholarly journals The physical states of the Hybrid Formalism

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Matthias R. Gaberdiel ◽  
Kiarash Naderi
Keyword(s):  
String Theory ◽  
Free Field ◽  
Vertex Operators ◽  
World Sheet ◽  
Brst Cohomology ◽  
The World ◽  
The Way

Abstract String theory on AdS3 × S3 × $$ \mathbbm{T} $$ T 4 with one unit (k = 1) of NS-NS flux is considered in the hybrid formalism of Berkovits, Vafa & Witten (BVW). Using the free field realisation of the world-sheet theory at k = 1, we identify explicitly the BRST cohomology classes corresponding to some of the low-lying states of the dual CFT. In particular, we do this for the $$ \mathcal{N} $$ N = 4 superconformal generators of the symmetric orbifold theory, and we confirm these identifications by showing that the worldsheet correlators reproduce the expected dual CFT answer. Along the way we note that the physical vertex operators on the worldsheet have a simpler form if one works with a different, but equivalent, choice for the BRST operators relative to BVW.

scholarly journals String theory and the CPT theorem on the world-sheet

1997 ◽  
Vol 485 (1-2) ◽  
pp. 241-271 ◽  
Author(s):  
Andrea Pasquinucci ◽  
Kaj Roland
Keyword(s):  
String Theory ◽  
World Sheet ◽  
The World ◽  
Cpt Theorem

scholarly journals JT gravity limit of Liouville CFT and matrix model

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Kenta Suzuki ◽  
Tadashi Takayanagi
Keyword(s):  
String Theory ◽  
Matrix Model ◽  
Semiclassical Limit ◽  
Liouville Theory ◽  
Partition Functions ◽  
Two Dimensional ◽  
De Sitter ◽  
World Sheet ◽  
Boundary Terms ◽  
The World

Abstract In this paper we study a connection between Jackiw-Teitelboim (JT) gravity on two-dimensional anti de-Sitter spaces and a semiclassical limit of c < 1 two-dimensional string theory. The world-sheet theory of the latter consists of a space-like Liouville CFT coupled to a non-rational CFT defined by a time-like Liouville CFT. We show that their actions, disk partition functions and annulus amplitudes perfectly agree with each other, where the presence of boundary terms plays a crucial role. We also reproduce the boundary Schwarzian theory from the Liouville theory description. Then, we identify a matrix model dual of our two-dimensional string theory with a specific time-dependent background in c = 1 matrix quantum mechanics. Finally, we also explain the corresponding relation for the two-dimensional de-Sitter JT gravity.

scholarly journals D-instantons in Type IIA string theory on Calabi-Yau threefolds

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Sergei Alexandrov ◽  
Ashoke Sen ◽  
Bogdan Stefański
Keyword(s):  
String Theory ◽  
Moduli Space ◽  
Mirror Symmetry ◽  
Homology Class ◽  
World Sheet ◽  
Perfect Agreement ◽  
Duality Symmetry ◽  
To Receive ◽  
Perturbative Corrections

Abstract Type IIA string theory compactified on a Calabi-Yau threefold has a hypermultiplet moduli space whose metric is known to receive non-perturbative corrections from Euclidean D2-branes wrapped on 3-cycles. These corrections have been computed earlier by making use of mirror symmetry, S-duality and twistorial description of quaternionic geometries. In this paper we compute the leading corrections in each homology class using a direct world-sheet approach without relying on any duality symmetry or supersymmetry. Our results are in perfect agreement with the earlier predictions.

scholarly journals Flavor moonshine

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Shotaro Shiba Funai ◽  
Hirotaka Sugawara
Keyword(s):  
Experimental Data ◽  
String Theory ◽  
Fourier Coefficient ◽  
Hierarchical Structure ◽  
Moduli Space ◽  
Modular Forms ◽  
Natural Law ◽  
Fourier Expansion ◽  
Mass Ratios ◽  
Kähler Potential

Abstract The flavor moonshine hypothesis is formulated to suppose that all particle masses (leptons, quarks, Higgs, and gauge particles—more precisely, their mass ratios) are expressed as coefficients in the Fourier expansion of some modular forms just as, in mathematics, dimensions of representations of a certain group are expressed as coefficients in the Fourier expansion of some modular forms. The mysterious hierarchical structure of the quark and lepton masses is thus attributed to that of the Fourier coefficient matrices of certain modular forms. Our intention here is not to prove this hypothesis starting from some physical assumptions but rather to demonstrate that this hypothesis is experimentally verified and, assuming that the string theory correctly describes the natural law, to calculate the geometry (Kähler potential and the metric) of the moduli space of the Calabi–Yau manifold, thus providing a way to calculate the metric of the Calabi–Yau manifold itself directly from the experimental data.

scholarly journals Twisted string theory in anti-de Sitter space

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Songyuan Li ◽  
Jan Troost
Keyword(s):  
String Theory ◽  
Boundary Energy ◽  
Three Dimensional ◽  
De Sitter Space ◽  
Momentum Tensor ◽  
Space Time ◽  
De Sitter ◽  
World Sheet ◽  
The World ◽  
Time Boundary

Abstract We construct a string theory in three-dimensional anti-de Sitter space-time that is independent of the boundary metric. It is a topologically twisted theory of quantum gravity. We study string theories with an asymptotic N = 2 superconformal symmetry and demonstrate that, when the world sheet coupling to the space-time boundary metric undergoes a U(1) R-symmetry twist, the space-time boundary energy-momentum tensor becomes topological. As a by-product of our analysis, we obtain the world sheet vertex operator that codes the space-time energy-momentum for conformally flat boundary metrics.

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