scholarly journals NONLINEAR SIGMA MODEL ON CONIFOLDS

2002 ◽  
Vol 17 (09) ◽  
pp. 517-533 ◽  
Author(s):  
R. PARTHASARATHY ◽  
K. S. VISWANATHAN
Keyword(s):  
Sigma Model ◽  
Equations Of Motion ◽  
Target Space ◽  
Warp Factor ◽  
Nonlinear Sigma Model ◽  
Explicit Solutions ◽  
Type Ii ◽  
Ricci Flat ◽  
Complex Dimension ◽  
Gauge Connection

Explicit solutions to the conifold equations with complex dimension n = 3, 4 in terms of complex coordinates (fields) are employed to construct the Ricci-flat Kähler metrics on these manifolds. The Kähler two-forms are found to be closed. The complex realization of these conifold metrics are used in the construction of two-dimensional nonlinear sigma model with the conifolds as target spaces. The action for the sigma model is shown to be bounded from below. By a suitable choice of the "integration constants", arising in the solution of Ricci flatness requirement, the metric and the equations of motion are found to be non-singular. As the target space is Ricci-flat, the perturbative one-loop counterterms being absent, the model becomes topological. The inherent U(1) fiber over the base of the conifolds is shown to correspond to a gauge connection in the sigma model. The same procedure is employed to construct the metric for the resolved conifold, in terms of complex coordinates and the action for a nonlinear sigma model with resolved conifold as target space, is found to have a minimum value, which is topological. The metric is expressed in terms of the six real coordinates and compared with earlier works. The harmonic function, which is the warp factor in Type II-B string theory, is obtained and the ten-dimensional warped metric has the AdS5 × X5 geometry.

scholarly journals Long way to Ricci flatness

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Jin Chen ◽  
Chao-Hsiang Sheu ◽  
Mikhail Shifman ◽  
Gianni Tallarita ◽  
Alexei Yung
Keyword(s):  
Sigma Model ◽  
Ultra Violet ◽  
The Other ◽  
Target Space ◽  
Linear Sigma Model ◽  
Close Relative ◽  
Two Dimensional ◽  
World Sheet ◽  
Ricci Flat ◽  
The World

Abstract We study two-dimensional weighted $$ \mathcal{N} $$ N = (2) supersymmetric ℂℙ models with the goal of exploring their infrared (IR) limit. 𝕎ℂℙ(N,$$ \tilde{N} $$ N ˜ ) are simplified versions of world-sheet theories on non-Abelian strings in four-dimensional $$ \mathcal{N} $$ N = 2 QCD. In the gauged linear sigma model (GLSM) formulation, 𝕎ℂℙ(N,$$ \tilde{N} $$ N ˜ ) has N charges +1 and $$ \tilde{N} $$ N ˜ charges −1 fields. As well-known, at $$ \tilde{N} $$ N ˜ = N this GLSM is conformal. Its target space is believed to be a non-compact Calabi-Yau manifold. We mostly focus on the N = 2 case, then the Calabi-Yau space is a conifold. On the other hand, in the non-linear sigma model (NLSM) formulation the model has ultra-violet logarithms and does not look conformal. Moreover, its metric is not Ricci-flat. We address this puzzle by studying the renormalization group (RG) flow of the model. We show that the metric of NLSM becomes Ricci-flat in the IR. Moreover, it tends to the known metric of the resolved conifold. We also study a close relative of the 𝕎ℂℙ model — the so called zn model — which in actuality represents the world sheet theory on a non-Abelian semilocal string and show that this zn model has similar RG properties.

scholarly journals GAUSS DECOMPOSITION, WAKIMOTO REALIZATION AND GAUGED WZNW MODELS

1994 ◽  
Vol 09 (11) ◽  
pp. 1009-1023
Author(s):  
H. ARFAEI ◽  
N. MOHAMMEDI
Keyword(s):  
Field Strength ◽  
Sigma Model ◽  
Target Space ◽  
Gauge Fields ◽  
Nonlinear Sigma Model ◽  
Model Interpretation ◽  
Gauss Decomposition ◽  
Wznw Model ◽  
Wakimoto Realization

The implications of gauging the Wess-Zumino-Novikov-Witten (WZNW) model using the Gauss decomposition of the group elements are explored. We show that, contrary to the standard gauging of WZNW models, this gauging is carried out by minimally coupling the gauge fields. We find that this gauging, in the case of gauging and Abelian vector subgroup, differs from the standard one by terms proportional to the field strength of the gauge fields. We prove that gauging an Abelian vector subgroup does not have a nonlinear sigma model interpretation. This is because the target-space metric resulting from the integration over the gauge fields is degenerate. We demonstrate, however, that this kind of gauging has a natural interpretation in terms of Wakimoto variables.

THE BOSONIC SIGMA MODEL ON A TOROIDAL SURFACE

2004 ◽  
Vol 19 (16) ◽  
pp. 2713-2720
Author(s):  
D. G. C. McKEON
Keyword(s):  
Riemannian Manifold ◽  
Sigma Model ◽  
Three Dimensional ◽  
The Other ◽  
Target Space ◽  
Dimensional Euclidean Space ◽  
Nonlinear Sigma Model ◽  
Two Dimensional ◽  
Toroidal Surface ◽  
Spherical Basis

The nonlinear sigma model with a two-dimensional basis space and an n-dimensional target space is considered. Two different basis spaces are considered; the first is an 0(2)×0(2) subspace of the 0(2,2) projective space related to the Minkowski basis space, and the other is a toroidal space embedded into three-dimensional Euclidean space, characterized by radii R and r. The target space is taken to be an arbitrarily curved Riemannian manifold. One-loop dependence on the renormalization induced scale μ is shown in the toroidal basis space to be the same as in a flat or spherical basis space.

scholarly journals METAPLECTIC SPINOR FIELDS AND GLOBAL ANOMALIES

1995 ◽  
Vol 10 (01) ◽  
pp. 65-88 ◽  
Author(s):  
M. REUTER
Keyword(s):  
Phase Space ◽  
Sigma Model ◽  
Target Space ◽  
Spin Manifold ◽  
Nonlinear Sigma Model ◽  
Metaplectic Representation ◽  
One Dimensional ◽  
Path Integral Representation ◽  
Infinite Dimensional ◽  
Spinor Fields

We investigate spinor fields on phase spaces. Under local frame rotations they transform according to the (infinite-dimensional, unitary) metaplectic representation of Sp(2N), which plays a role analogous to the Lorentz group. We introduce a one-dimensional nonlinear sigma model whose target space is the phase space under consideration. The global anomalies of this model are analyzed, and it is shown that its fermionic partition function is anomalous exactly if the underlying phase space is not a spin manifold, i.e. if metaplectic spinor fields cannot be introduced consistently. The sigma model is constructed by giving a path integral representation to the Lie transport of spinors along the Hamiltonian flow.

scholarly journals Type II DFT solutions from Poisson–Lie $T$-duality/plurality

2019 ◽  
Vol 2019 (7) ◽  
Author(s):  
Yuho Sakatani
Keyword(s):  
Field Theory ◽  
General Class ◽  
Isometry Group ◽  
Equations Of Motion ◽  
Target Space ◽  
Transformation Rule ◽  
Type Ii ◽  
Duality Transformation ◽  
Duality Symmetry ◽  
Double Field Theory

Abstract String theory has $T$-duality symmetry when the target space has Abelian isometries. A generalization of $T$-duality, where the isometry group is non-Abelian, is known as non-Abelian $T$-duality, which works well as a solution-generating technique in supergravity. In this paper we describe non-Abelian $T$-duality as a kind of $\text{O}(D,D)$ transformation when the isometry group acts without isotropy. We then provide a duality transformation rule for the Ramond–Ramond fields by using the technique of double field theory (DFT). We also study a more general class of solution-generating technique, the Poisson–Lie (PL) $T$-duality or $T$-plurality. We describe the PL $T$-plurality as an $\text{O}(n,n)$ transformation and clearly show the covariance of the DFT equations of motion by using the gauged DFT. We further discuss the PL $T$-plurality with spectator fields, and study an application to the $\text{AdS}_5\times\text{S}^5$ solution. The dilaton puzzle known in the context of the PL $T$-plurality is resolved with the help of DFT.

scholarly journals Higgs inflation as nonlinear sigma model and scalaron as its σ-meson

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Yohei Ema ◽  
Kyohei Mukaida ◽  
Jorinde van de Vis
Keyword(s):  
Sigma Model ◽  
Planck Scale ◽  
Scalar Fields ◽  
Target Space ◽  
Linear Sigma Model ◽  
Nonlinear Sigma Model ◽  
Jordan Frame ◽  
Quadratic Gravity ◽  
Frame Transformation ◽  
Definition Of

Abstract We point out that a model with scalar fields with a large nonminimal coupling to the Ricci scalar, such as Higgs inflation, can be regarded as a nonlinear sigma model (NLSM). With the inclusion of not only the scalar fields but also the conformal mode of the metric, our definition of the target space of the NLSM is invariant under the frame transformation. We show that the σ-meson that linearizes this NLSM to be a linear sigma model (LSM) corresponds to the scalaron, the degree of freedom associated to the R2 term in the Jordan frame. We demonstrate that quantum corrections inevitably induce this σ-meson in the large-N limit, thus providing a frame independent picture for the emergence of the scalaron. The resultant LSM only involves renormalizable interactions and hence its perturbative unitarity holds up to the Planck scale unless it hits a Landau pole, which is in agreement with the renormalizability of quadratic gravity.

scholarly journals A non-relativistic limit of NS-NS gravity

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
E. A. Bergshoeff ◽  
J. Lahnsteiner ◽  
L. Romano ◽  
J. Rosseel ◽  
C. Şimşek
Keyword(s):  
Scale Invariance ◽  
Sigma Model ◽  
Equations Of Motion ◽  
Geometric Constraints ◽  
Target Space ◽  
Kinetic Term ◽  
Scale Invariant ◽  
Relativistic Limit ◽  
Cartan Geometry ◽  
Form Field

Abstract We discuss a particular non-relativistic limit of NS-NS gravity that can be taken at the level of the action and equations of motion, without imposing any geometric constraints by hand. This relies on the fact that terms that diverge in the limit and that come from the Vielbein in the Einstein-Hilbert term and from the kinetic term of the Kalb-Ramond two-form field cancel against each other. This cancelling of divergences is the target space analogue of a similar cancellation that takes place at the level of the string sigma model between the Vielbein in the kinetic term and the Kalb-Ramond field in the Wess-Zumino term. The limit of the equations of motion leads to one equation more than the limit of the action, due to the emergence of a local target space scale invariance in the limit. Some of the equations of motion can be solved by scale invariant geometric constraints. These constraints define a so-called Dilatation invariant String Newton-Cartan geometry.

scholarly journals Cosmological sigma model with non-minimal coupling to the target space

Open Physics ◽  
2014 ◽  
Vol 12 (1) ◽  
Author(s):  
Victor Shchigolev
Keyword(s):  
Sigma Model ◽  
Preliminary Investigation ◽  
Component Model ◽  
Target Space ◽  
Nonlinear Sigma Model ◽  
Minimal Coupling ◽  
Isotropic Universe ◽  
Two Component

AbstractA homogeneous and isotropic Universe in the framework of a nonlinear sigma model with non-minimal coupling to the target space is considered. Preliminary investigation of a two-component model of this sort is conducted. Some solutions for this model are given. Perspectives and directions of development of such a sort of models are discussed.

scholarly journals CANCELLATION OF UV DIVERGENCES IN THE ${\mathcal N} = 4$ SUSY NONLINEAR SIGMA MODEL IN THREE DIMENSIONS

2001 ◽  
Vol 16 (25) ◽  
pp. 1643-1650 ◽  
Author(s):  
TAKEO INAMI ◽  
YORINORI SAITO ◽  
MASAYOSHI YAMAMOTO
Keyword(s):  
Cotangent Bundle ◽  
Sigma Model ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Target Space ◽  
Quantum Corrections ◽  
Nonlinear Sigma Model ◽  
Leading Order ◽  
Β Function

We study the uv properties of the three-dimensional [Formula: see text] SUSY nonlinear sigma model whose target space is T*(CPN-1) (the cotangent bundle of CPN-1) to higher orders in the 1/N expansion. We calculate the β-function to next-to-leading order and verify that it has no quantum corrections at leading and next-to-leading orders.

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