scholarly journals The closure constraint for the hyperbolic tetrahedron as a Bianchi identity

2017 ◽  
Vol 49 (7) ◽  
Author(s):  
Christoph Charles ◽  
Etera R. Livine
2021 ◽  
Vol 104 (10) ◽  
Author(s):  
Vincent Lahoche ◽  
Bêm-Biéri Barthélemy Natta ◽  
Dine Ousmane Samary

2003 ◽  
Vol 40 (1) ◽  
pp. 129-167 ◽  
Author(s):  
Jung-Hwan Kwon ◽  
Yong-Soo Pyo ◽  
Young-Jin Suh

2017 ◽  
Vol 18 (1) ◽  
pp. 66-71
Author(s):  
Mehran Taki ◽  
Abolfazl Mirjalili

2011 ◽  
Vol 26 (06) ◽  
pp. 415-421 ◽  
Author(s):  
PRASANTA MAHATO ◽  
PARTHA BHATTACHARYA

In the torsion ⊗ curvature approach of gravity Chern–Simons modification has been considered here. It has been found that Chern–Simons contribution to the Bianchi identity cancels from that of the scalar field part. But "homogeneity and isotropy" consideration of present day cosmology is a consequence of the "strong equivalence principle" and vice versa.


2021 ◽  
Author(s):  
Shiladittya Debnath

Abstract In this letter, we investigate the basic property of the Hilbert-Einstein action principle and its infinitesimal variation under suitable transformation of the metric tensor. We find that for the variation in action to be invariant, it must be a scalar so as to obey the principle of general covariance. From this invariant action principle, we eventually derive the Bianchi identity (where, both the 1st and 2nd forms are been dissolved) by using the Lie derivative and Palatini identity. Finally, from our derived Bianchi identity, splitting it into its components and performing cyclic summation over all the indices, we eventually can derive the covariant derivative of the Riemann curvature tensor. This very formulation was first introduced by S Weinberg in case of a collision less plasma and gravitating system. We derive the Bianchi identity from the action principle via this approach; and hence the name ‘Weinberg formulation of Bianchi identity’.


Author(s):  
Nikolay Abrosimov ◽  
Bao Vuong

We consider a compact hyperbolic tetrahedron of a general type. It is a convex hull of four points called vertices in the hyperbolic space [Formula: see text]. It can be determined by the set of six edge lengths up to isometry. For further considerations, we use the notion of edge matrix of the tetrahedron formed by hyperbolic cosines of its edge lengths. We establish necessary and sufficient conditions for the existence of a tetrahedron in [Formula: see text]. Then we find relations between their dihedral angles and edge lengths in the form of a cosine rule. Finally, we obtain exact integral formula expressing the volume of a hyperbolic tetrahedron in terms of the edge lengths. The latter volume formula can be regarded as a new version of classical Sforza’s formula for the volume of a tetrahedron but in terms of the edge matrix instead of the Gram matrix.


2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Takashi Hiramatsu ◽  
Masahiro Ibe ◽  
Motoo Suzuki ◽  
Soma Yamaguchi

Abstract We discuss how the topological defects in the dark sector affect the Standard Model sector when the dark photon has a kinetic mixing with the QED photon. In particular, we consider the dark photon appearing in the successive gauge symmetry breaking, SU(2) → U(1) → ℤ2, where the remaining ℤ2 is the center of SU(2). In this model, the monopole is trapped into the cosmic strings and forms the so-called bead solution. As we will discuss, the dark cosmic string induces the QED magnetic flux inside the dark string through the kinetic mixing. The dark monopole, on the other hand, does not induce the QED magnetic flux in the U(1) symmetric phase, even in the presence of the kinetic mixing. Finally, we show that the dark bead solution induces a spherically symmetric QED magnetic flux through the kinetic mixing. The induced flux looks like the QED magnetic monopole viewed from a distance, although QED satisfies the Bianchi identity everywhere, which we call a pseudo magnetic monopole.


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