arXiv subjects

Kameshwar C. Wali

Publications and source records attributed to Kameshwar C. Wali.

17 recordsLinked to original sources

arXiv2017

Einstein-Yang-Mills-Dirac systems from the discretized Kaluza-Klein theory

A unified theory of the non-Abelian gauge interactions with gravity in the framework of a discretized Kaluaza-Kleine theory is constructed with a modified Dirac operator and wedge product. All the couplings of chiral spinors to the non-Abelian gauge fields emerge naturally as components of the couplings of the chiral spinors to the generalized gravity together with some new interactions. In particular, the currently prevalent gravity-QCD-quark and gravity-electroweak-quark-lepton models are shown to follow as special cases of the general framework.

hep-th↗

arXiv2012

A metric theory of gravity with torsion in extra-dimension

We consider a theory of gravity with a hidden extra-dimension and metric-dependent torsion. A set of physically motivated constraints are imposed on the geometry so that the torsion stays confined to the extra-dimension and the extra-dimension stays hidden at the level of four dimensional geodesic motion. At the kinematic level, the theory maps on to General Relativity, but the dynamical field equations that follow from the action principle deviate markedly from the standard Einstein equations. We study static spherically symmetric vacuum solutions and homogeneous-isotropic cosmological solutions that emerge from the field equations. In both cases, we find solutions of significant physical interest. Most notably, we find positive mass solutions with naked singularity that match the well known Schwarzschild solution at large distances but lack an event horizon. In the cosmological context, we find oscillatory scenario in contrast to the inevitable, singular big bang of the standard cosmology.

gr-qc↗

arXiv2010

Kaluza-Klein Theory with Torsion confined to the Extra-dimension

Here we consider a variant of the 5 dimensional Kaluza-Klein theory within the framework of Einstein-Cartan formalism that includes torsion. By imposing a set of constraints on torsion and Ricci rotation coefficients, we show that the torsion components are completely expressed in terms of the metric. Moreover, the Ricci tensor in 5D corresponds exactly to what one would obtain from torsion-free general relativity on a 4D hypersurface. The contributions of the scalar and vector fields of the standard K-K theory to the Ricci tensor and the affine connections are completely nullified by the contributions from torsion. As a consequence, geodesic motions do not distinguish the torsion free 4D space-time from a hypersurface of 5D space-time with torsion satisfying the constraints. Since torsion is not an independent dynamical variable in this formalism, the modified Einstein equations are different from those in the general Einstein-Cartan theory. This leads to important cosmological consequences such as the emergence of cosmic acceleration.

gr-qc↗

arXiv2008

SU(5) grand unification on a domain-wall brane from an E_6-invariant action

An SU(5) grand unification scheme for effective 3+1-dimensional fields dynamically localised on a domain-wall brane is constructed. This is achieved through the confluence of the clash-of-symmetries mechanism for symmetry breaking through domain-wall formation, and the Dvali-Shifman gauge-boson localisation idea. It requires an E_6 gauge-invariant action, yielding a domain-wall solution that has E_6 broken to differently embedded SO(10) x U(1) subgroups in the two bulk regions on opposite sides of the wall. On the wall itself, the unbroken symmetry is the intersection of the two bulk subgroups, and contains SU(5). A 4+1-dimensional fermion family in the 27 of E_6 gives rise to localised left-handed zero-modes in the 5^* + 10 + 1 + 1 representation of SU(5). The remaining ten fermion components of the 27 are delocalised exotic states, not appearing in the effective 3+1-dimensional theory on the domain-wall brane. The scheme is compatible with the type-2 Randall-Sundrum mechanism for graviton localisation; the single extra dimension is infinite.

hep-ph↗

arXiv2007

Baryons and Mesons with Beauty

Recent experimental findings of several mesons and baryons with "beauty" and "charm" as flavors remind us of the days when strangeness was discovered, and how its inclusion led to SU(3)-flavor symmetry with enormous success in the classification of the "proliferated" states into SU(3) multiplets. One of the key elements was the successful application of the first order perturbation in symmetry breaking, albeit what then appeared to be huge mass differences, and the prediction of new states that were confirmed by experiments. In this note, we venture into the past and, applying the same techniques, predict some new "beauty-" and "charm-" flavored hadrons. If these new states are confirmed experimentally, it may provide a useful phenomenological model for classifying numerous states that are found to be in the PDG data and could invite further theoretical challenges towards our understanding of symmetry breaking.

hep-ph↗

arXiv2006

Clash of Symmetries in a Brane World Picture

If our (3+1) dimensional universe is a brane or domain wall embedded in a higher dimensional space, then a phenomenon that may be designated as "Clash of Symmetries" provides a new method of breaking continuous symmetries. The paper presents some non-trivial models containing the physical ideas.

hep-th↗

arXiv2005

The Higgs Sector on a Two-Sheeted Space Time

We present a general formalism based on the framework of non-commutative geometry, suitable to the study the standard model of electroweak interactions, as well as that of more general gauge theories. Left- and right-handed chiral fields are assigned to two different sheets of space-time (a discretized version of Kaluza-Klein theory). Scalar Higgs fields find themselves treated on the same footing as the gauge fields, resulting in spontaneous symmetry breaking in a natural and predictable way. We first apply the formalism to the Standard Model, where one can predict the Higgs mass and the top Yukawa coupling. We then study the left-right symmetric model, where we show that this framework imposes constraints on the type and coefficients of terms appearing in the Higgs potential.

hep-ph↗

arXiv2004

What are the Building Blocks of Our Universe?

We are told that we are living in a Golden Age of Astronomy. Cosmological Parameters are found with un precedented accuracy. Yet, the known form of matter forms only a small fraction of the total energy density of the universe. Also, a mysterious dark energy dominates the universe and causes acceleration in the rate of expansion.

astro-ph↗

arXiv2003

Chiral spinors and gauge fields in noncommutative curved space-time

The fundamental concepts of Riemannian geometry, such as differential forms, vielbein, metric, connection, torsion and curvature, are generalized in the context of non-commutative geometry. This allows us to construct the Einstein-Hilbert-Cartan terms, in addition to the bosonic and fermionic ones in the Lagrangian of an action functional on non-commutative spaces. As an example, and also as a prelude to the Standard Model that includes gravitational interactions, we present a model of chiral spinor fields on a curved two-sheeted space-time with two distinct abelian gauge fields. In this model, the full spectrum of the generalized metric consists of pairs of tensor, vector and scalar fields. They are coupled to the chiral fermions and the gauge fields leading to possible parity violation effects triggered by gravity.

hep-th↗

arXiv2000

Matter Fields in Curved Space-Time

We study the geometry of a two-sheeted space-time within the framework of non-commutative geometry. As a prelude to the Standard Model in curved space-time, we present a model of a left- and a right- chiral field living on the two sheeted-space time and construct the action functionals that describe their interactions.

hep-th↗

arXiv1998

Black holes with magnetic charge and quantized mass

We examine the issue of magnetic charge quantization in the presence of black holes. It is pointed out that quantization of magnetic charge can lead to the mass quantization for magnetically charged black holes. We also discuss some implications for the experimental searches of magnetically charged black holes.

hep-ph↗

arXiv1995

A Discretized Version of Kaluza-Klein Theory with Torsion and Massive Fields

We consider an internal space of two discrete points in the fifth dimension of the Kaluza-Klein theory by using the formalism of noncommutative geometry developed in a previous paper \cite{VIWA} of a spacetime supplemented by two discrete points. With the nonvanishing internal torsion 2-form there are no constraints implied on the vielbeins. The theory contains a pair of tensor, a pair of vector and a pair of scalar fields. Using the generalized Cartan structure equation we are able not only to determine uniquely the hermitian and metric compatible connection 1-forms, but also the nonvanishing internal torsion 2-form in terms of vielbeins. The resulting action has a rich and complex structure, a particular feature being the existence of massive modes. Thus the nonvanishing internal torsion generates a Kaluza-Klein type model with zero and massive modes.

hep-th↗

arXiv1995

Chern-Simons terms in Noncommutative Geometry and its application to Bilayer Quantum Hall Systems

Considering bilayer systems as extensions of the planar ones by an internal space of two discrete points, we use the ideas of Noncommutative Geometry to construct the gauge theories for these systems. After integrating over the discrete space we find an effective $2+1$ action involving an extra complex scalar field, which can be interpreted as arising from the tunneling between the layers. The gauge fields are found in different phases corresponding to the different correlations due to the Coulomb interaction between the layers. In a particular phase, when the radial part of the complex scalar field is a constant, we recover the Wen-Zee model of Bilayer Quantum Hall systems. There are some circumstances, where this radial part may become dynamical and cause dissipation in the oscillating supercurrent between the layers.

hep-th↗

arXiv1994

Noncommutative Geometry and a Discretized Version of Kaluza-Klein Theory with a Finite Field Content

We consider a four-dimensional space-time supplemented by two discrete points assigned to a $Z_2$ algebraic structure and develop the formalism of noncommutative geometry. By setting up a generalised vielbein, we study the metric structure. Metric compatible torsion free connection defines a unique finite field content in the model and leads to a discretized version of Kaluza-Klein theory. We study some special cases of this model that illustrate the rich and complex structure with massive modes and the possible presence of a cosmological constant.

hep-th↗

arXiv1994

Gravity and Electromagnetism in Noncommutative Geometry

We present a unified description of gravity and electromagnetism in the framework of a $Z_2$ noncommutative differential calculus. It can be considered as a ``discrete version" of Kaluza-Klein theory, where the fifth continuous dimension is replaced by two discrete points. We derive an action which coincides with the dimensionally reduced one of the ordinary Kaluza-Klein theory.

hep-th↗

arXiv1993

Magnetic Monopoles in the Einstein-Yang-Mills-Higgs System

We study the Yang-Mills-Higgs system within the framework of general relativity. In the static situation, using Bogomol'nyi type analysis, we derive a positive-definite energy functional which has a lower bound. Specializing to the gauge group $SU(2)$ and the t'Hooft-Polyakov ansatz for the gauge and Higgs fields, we seek static, spherically symmetric solutions to the coupled system of equations in both the isotropic and standard coordinate systems. In both cases, in the spontaneously broken symmetry situation, we find great simplications reducing the solutions of the coupled system to the solution of a single non-linear differential equation, different one in each case, but well-known in other contexts of physics. We find abelian and non-abelian monopole solutions with gravitational fields playing the role of Higgs fields in providing attraction that balances the repulsion due to the gauge fields. Numerical solutions indicate the possibility of blackhole horizons inside the monopoles enclosing the singularity at the origin. Such non-abelian monopoles are then the analogs of Reissner-Nordström blackholes with magnetic charge.

hep-ph↗

arXiv1992

Non-Abelian Monopoles Coupled to Gravity

A static configuration of point charges held together by the gravitational attraction is known to be given by the Majumdar-Papapetrou solution in the Einstein-Maxwell theory. We consider a generalization of this solution to non-Abelian monopoles of the Yang-Mills Higgs system coupled to gravity. The solution is governed by an analog of the Bogomol'nyi equations that had played a central role in the analysis of non-Abelian monopoles.

hep-th↗