33,226 research outputs found
Bott-Chern cohomology of solvmanifolds
No full textWe study conditions under which sub-complexes of a double complex of vector
spaces allow to compute the Bott-Chern cohomology. We are especially aimed at
studying the Bott-Chern cohomology of a special class of solvmanifolds
Symplectic Bott-Chern cohomology of solvmanifolds
No full textWe study the symplectic Bott-Chern cohomology by L.-S. Tseng and S.-T. Yau
for solvmanifolds endowed with left-invariant symplectic structures
Perturbative and Non-perturbative Aspects of the Chern-Simons-Witten Theory
Full text linkWe investigate a relation between non-perturbative and perturbative cases in the 2+1 dimensional Chern-Simons-
Witten (CSW) theory for G = E6 gauge group. In the perturbative case, we calculate the vacuum expectation value(VEV) of an unknotted Wilson loop operator up to order 1/k3 (k is a coupling constant). The result above is proved
to be identical to the polynomial invariant E0 (ρ) in the non-perturbative case at the same order of expansion
Chern-flat and Ricci-flat invariant almost Hermitian structure
Full text linkWe study nilmanifolds endowed with a Chern connectio
Quasi-Kahler Chern-flat manifolds and complex 2-step nilpotent Lie algebras
Full text linkThe study of quasi-Kaehler Chern-flat almost Hermitian manifolds is strictly related to the study of anti-bi-invariant almost complex Lie algebras. In the present paper we show that quasi-Kaehler Chern-flat almost Hermitian structures on compact manifolds are in correspondence to complex parallelisable Hermitian structures satisfying the second Gray identity. From an algebraic point of view this correspondence reads as a natural correspondence between anti-bi-invariant almost complex structures on Lie algebras to bi-invariant complex structures. Some natural algebraic problems are approached and some exotic examples are carefully describe
Electrical transport properties of n-type (110)-oriented bismuth thin films grown at 110 K on glass substrates
No full textCubic 3D Chern photonic insulators with orientable large Chern vectors
Full text linkChern number controls the number of surface state channels in topological insulators. Here the authors propose 3D Chern insulating cubic photonic crystals with orientable and arbitrarily large Chern numbers demonstrating topologically protected photonic surface states. Time Reversal Symmetry (TRS) broken topological phases provide gapless surface states protected by topology, regardless of additional internal symmetries, spin or valley degrees of freedom. Despite the numerous demonstrations of 2D topological phases, few examples of 3D topological systems with TRS breaking exist. In this article, we devise a general strategy to design 3D Chern insulating (3D CI) cubic photonic crystals in a weakly TRS broken environment with orientable and arbitrarily large Chern vectors. The designs display topologically protected chiral and unidirectional surface states with disjoint equifrequency loops. The resulting crystals present the following characteristics: First, by increasing the Chern number, multiple surface states channels can be supported. Second, the Chern vector can be oriented along any direction simply changing the magnetization axis, opening up larger 3D CI/3D CI interfacing possibilities as compared to 2D. Third, by lowering the TRS breaking requirements, the system is ideal for realistic photonic applications where the magnetic response is weak
Scattering Amplitudes of Massive N=2 Gauge Theories in Three Dimensions
Full text linkWe study the scattering amplitudes of mass-deformed Chern-Simons theories and Yang-Mills-Chern-Simons theories with N=2 supersymmetry in three dimensions. In particular, we derive the on-shell supersymmetry algebras which underlie the scattering matrices of these theories. We then compute various 3 and 4-point on-shell tree-level amplitudes in these theories. For the mass-deformed Chern-Simons theory, odd-point amplitudes vanish and we find that all of the 4-point amplitudes can be encoded elegantly in superamplitudes. For the Yang-Mills-Chern-Simons theory, we obtain all of the 4-point tree-level amplitudes using a combination of perturbative techniques and algebraic constraints and we comment on difficulties related to computing amplitudes with external gauge fields using Feynman diagrams. Finally, we propose a BCFW recursion relation for mass-deformed theories in three dimensions and discuss the applicability of this proposal to mass-deformed N=2 theories
Topics in Supersymmetry Breaking and Gauge/Gravity Dualities
Full text linkThe thesis covers two topics in string theory and quantum field theory. First, we realize metastable vacua in various supersymmetric gauge theories. Specifically, we consider the Coulomb branch of any N = 2 supersymmetric gauge theory, and perturb it by a superpotential and engineer a metastable vacuum at a point. We also study its relation to Kahler normal coordinates and Fayet-Iliopoulos terms. Having studied the metastable construction, we apply this to general gauge mediation. We show how to compute the current correlators when the hidden sector is strongly coupled in specific examples.
Next, we consider gauge/gravity dualities. We apply dualities to the investigation of various strongly coupled field theories. In one example, we construct M-theory supergravity solutions with the nonrelativistic Schroedinger symmetry starting from the warped AdS_5 metric with N = 1 supersymmetry. We impose that the lightlike direction is compact by making it a nontrivial U(1) bundle over the compact space. In another example, we show that, in a gravity theory with a Chern-Simons coupling, the Reissner-Nordstrom black hole in anti-de Sitter space is unstable depending on the value of the Chern-Simons coupling. The analysis suggests that the final configuration is likely to be a spatially modulated phase.</p
Multiple membranes in M-theory
No full textJB acknowledges support from the U.S. National Science Foundation, grant NSF-PHY-0910467. NL was supported in part by STFC grant ST/G000395/1. CP is supported by the U.S. Department of Energy under grant DE-FG02-96ER40959
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