Helicity flip cross section from gravity with torsion

Hammond, Richard T.

doi:10.1088/0264-9381/13/7/002

Cited by 22 publications

(31 citation statements)

References 28 publications

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“…The same concerns the creation of particles by external torsion field [158] and the helicity flip for the solar neutrino which could be, in principle, induced by torsion [96].…”

Section: Experimental Constraints For the Constant Background Torsionmentioning

confidence: 99%

Physical aspects of the space–time torsion

2002

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Abstract. We review many quantum aspects of torsion theory and discuss the possibility of the space-time torsion to exist and to be detected. The paper starts, in Chapter 2, with a pedagogical introduction to the classical gravity with torsion, that includes also interaction of torsion with matter fields. Special attention is paid to the conformal properties of the theory. In Chapter 3, the renormalization of quantum theory of matter fields and related topics, like renormalization group, effective potential and anomalies, are considered. Chapter 4 is devoted to the action of spinning and spinless particles in a space-time with torsion, and to the discussion of possible physical effects generated by the background torsion. In particular, we review the upper bounds for the magnitude of the background torsion which are known from the literature. In Chapter 5, the comprehensive study of the possibility of a theory for the propagating completely antisymmetric torsion field is presented. It is supposed that the propagating field should be quantized, and that its quantum effects must be described by, at least, some effective low-energy quantum field theory. We show, that the propagating torsion may be consistent with the principles of quantum theory only in the case when the torsion mass is much greater than the mass of the heaviest fermion coupled to torsion. Then, universality of the fermion-torsion interaction implies that torsion itself has a huge mass, and can not be observed in realistic experiments. Thus, the theory of quantum matter fields on the classical torsion background can be formulated in a consistent way, while the theory of dynamical torsion meets serious obstacles. In Chapter 6, we briefly discuss the string-induced torsion and the possibility to induce torsion action and torsion itself through the quantum effects of matter fields.

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“…The same concerns the creation of particles by external torsion field [158] and the helicity flip for the solar neutrino which could be, in principle, induced by torsion [96].…”

Section: Experimental Constraints For the Constant Background Torsionmentioning

confidence: 99%

Physical aspects of the space–time torsion

2002

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“…This effects could be important for testing some astrophysical consequences of torsion [9] because of smallness of coupling constant with respect to the other fundamental interactions.…”

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confidence: 99%

“…The non-holonomic index a labels the vierbein, while the holonomic index µ labels the components of a given vierbein. The connection in non-holonomic coordinates is given by [9] …”

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Fermion helicity flip induced by torsion field

Capozziello¹,

Iovane²,

Lambiase³

et al. 1999

Europhys. Lett.

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PACS. 14.60Pq -Neutrino mass and mixing. PACS. 95.30Sf -Relativity and gravitation. PACS. 04.50+h -Alternative theories of gravity.Abstract. -We show that in theories of gravitation with torsion the helicity of fermion particles is not conserved and we calculate the probability of spin flip, which is related to the anti-symmetric part of affine connection. Some cosmological consequences are discussed.Introduction. -Attempts to conciliate General Relativity with Quantum Theory yielded to propose theories of gravitation including torsion fields, so that the natural arena is the space-time U 4 that is a generalization of Riemann manifold V 4 .The advantage to pass from V 4 to U 4 is due to the fact that the spin of a particle turns out to be related to the torsion just as its mass is responsable of the curvature. From this point of view, such a generalization tries to include the spin fields of matter into the same geometrical scheme of General Relativity.One of the attempts in this direction is the Einstein-Cartan-Sciama-Kibble (ECSK) theory [1]. However the torsion seems to play an important role in any fundamental theory. For instance: a torsion field appears in (super)string theory if we consider string fundamental modes; we need, at least, a scalar mode and two tensor modes: a symmetric and antisymmetric one. The latter, in the low energy limit for string effective action, gives the effects of a torsion field [2]; any attempts of unification between gravity and electromagnetism require the inclusion torsion in four and in higher-dimensional theories as Kaluza-Klein ones [3]; theories of gravity formulated in terms of twistors need the inclusion of torsion [4]; in the supergravity theory torsion, curvature and matter fields are treated under the same standard [5]; in cosmology torsion could have had a relevant role into dynamics of the early universe because it gives a

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“…The spin-flip cross section in a torsion field of the string theory type has been derived in Ref. [12], and I will only briefly sketch the derivation here. Details can be found ibid.…”

Section: Spin Flip Due To Torsionmentioning

confidence: 99%

Letter: Effects of a Torsion Field on Big Bang Nucleosynthesis

Brüggen¹

1999

General Relativity and Gravitation

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In this paper it is investigated whether torsion, which arises naturally in most theories of quantum gravity, has observable implications for the Big Bang nucleosynthesis. Torsion can lead to spin flips amongst neutrinos thus turning them into sterile neutrinos. In the early Universe they can alter the helium abundance which is tightly constrained by observations. Here I calculate to what extent torsion of the string theory type leads to a disagreement with the Big Bang nucleosynthesis predictions.

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Helicity flip cross section from gravity with torsion

Cited by 22 publications

References 28 publications

Physical aspects of the space–time torsion

Physical aspects of the space–time torsion

Fermion helicity flip induced by torsion field

Letter: Effects of a Torsion Field on Big Bang Nucleosynthesis

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