K-algebras and K-spaces of constant type with indefinite metric

1981 ◽  
Vol 29 (2) ◽  
pp. 136-143
Author(s):  
V. F. Kirichenko
2011 ◽  
Vol 20 (13) ◽  
pp. 2543-2558 ◽  
Author(s):  
SAMUEL LEPE ◽  
JAVIER LORCA ◽  
FRANCISCO PEÑA ◽  
YERKO VÁSQUEZ

From a variational action with nonminimal coupling with a scalar field and classical scalar and fermionic interaction, cosmological field equations can be obtained. Imposing a Friedmann–Lemaître–Robertson–Walker (FLRW) metric, the equations lead directly to a cosmological model consisting of two interacting fluids, where the scalar field fluid is interpreted as dark energy and the fermionic field fluid is interpreted as dark matter. Several cases were studied analytically and numerically. An important feature of the non-minimal coupling is that it allows crossing the barrier from a quintessence to phantom behavior. The insensitivity of the solutions to one of the parameters of the model permits it to find an almost analytical solution for the cosmological constant type of universe.


2018 ◽  
Vol 27 (1) ◽  
pp. 57-62
Author(s):  
İlim Kişi ◽  
◽  
Sezgin Büyükkütük ◽  
Günay Öztürk ◽  
◽  
...  

In this paper, we consider unit speed timelike curves in pseudo-Galilean 3-space \mathbb{G}_{3}^{1} as curves whose position vectors can be written as linear combination of their Serret-Frenet vectors. We obtain some results of constant ratio curves and give an example of these curves. Further, we show that there is no T-constant curve and we obtain some results of N-constant type of curves in pseudo-Galilean 3-space \mathbb{G}_{3}^{1}.


2001 ◽  
Vol 216 (3) ◽  
pp. 491-513 ◽  
Author(s):  
Sergio Albeverio ◽  
Hanno Gottschalk

2021 ◽  
Vol 2038 (1) ◽  
pp. 012009
Author(s):  
Joshua Feinberg ◽  
Roman Riser

Abstract We review our recent results on pseudo-hermitian random matrix theory which were hitherto presented in various conferences and talks. (Detailed accounts of our work will appear soon in separate publications.) Following an introduction of this new type of random matrices, we focus on two specific models of matrices which are pseudo-hermitian with respect to a given indefinite metric B. Eigenvalues of pseudo-hermitian matrices are either real, or come in complex-conjugate pairs. The diagrammatic method is applied to deriving explicit analytical expressions for the density of eigenvalues in the complex plane and on the real axis, in the large-N, planar limit. In one of the models we discuss, the metric B depends on a certain real parameter t. As t varies, the model exhibits various ‘phase transitions’ associated with eigenvalues flowing from the complex plane onto the real axis, causing disjoint eigenvalue support intervals to merge. Our analytical results agree well with presented numerical simulations.


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