On the relativistic spin projection operators

In the Rarita-Schwinger formalism, the relativistic spin projection operators are discussed with the help of the Pauli-Lubanski four-vector. It is shown that this approach is equivalent to the conventional one, but moreover, it enables one to derive recurrence relations for the spin projection operators. Such relations can be useful in practical applications.     

Rarita-Schwinger field: Dressing procedure and spin-parity of components

A general form of the total nonrenormalized propagator for a massive Rarita-Schwinger field is obtained with allowance for all spin components. The dressing of two opposite-parity Dirac fermions in the presence of mutual transitions is the closest analogy of dressing in the s = 1/2 sector of the Rarita-Schwinger field. A calculation of self-energy contributions confirms that the Rarita-Schwinger field involves, in addition to a leading component of spin s = 3/2, two opposite-parity components of spin s = 1/2.     

Toward a theory of particles with 3/2 spin

A detailed analysis is performed of the pattern of meshes of irreducible Lorentz group representations corresponding to the direct product of vector and bispinor representations within the framework of the Gel'fand-Yaglom approach, for the purpose of determining the possibility of constructing various relativistic wave equations describing particles with a maximum spin of 3/2. Two such new equations are constructed for a 3/2 spin, which differ from the generally known Rarita-Schwinger and Fierz-Pauli equations. The nonequivalence of the latter is also proven.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 91–95, January, 1985.     

Feynman propagator for a particle with arbitrary spin

Based on the solution to the Rarita-Schwinger equations, a direct derivation of the projection operator and propagator for a particle with arbitrary spin is worked out. The projection operator constructed by Behrends and Fronsdal is re-deduced and confirmed, and simplified in the case of half-integral spin; the general commutation rules and Feynman propagator for a free particle of any spin are derived, and explicit expressions for the propagators for spins 3/2, 2, 5/2, 3, 7/2, 4 are provided.Received: 13 March 2003, Revised: 24 April 2005, Published online: 6 July 2005     

Field Equations of Arbitrary Spin in Space-time with Torsion

A two spinor lagrangian formulation of field equations for massive particle of arbitrary spin is proposed in a curved space-time with torsion. The interaction between fields and torsion is expressed by generalizing the situation of the Dirac equation. The resulting field equations are different (except for the spin-1/2 case) from those obtained by promoting the covariant derivatives of the torsion free equations to include torsion. The non linearity of the equations, that is induced by torsion, can be interpreted as a self-interaction of the particle. The spin-1 and spin-3/2 cases are studied with some details by translating into tensor form. There result the Proca and Rarita-Schwinger field equations with torsion, respectively. PACS numbers: 03.65.Pm; 04.20.Cv; 04.20.Fy.     

Massive spin 3/2 theories in 3 dimensions

Topologically massive spin 3/2 theory in 3 spacetime dimensions, which is gauge invariant and involves second derivatives, is shown to be equivalent to the normal gauge variant first derivative massive Rarita-Schwinger model. The equivalence persists in arbitrary background geometries. In the particular anti-de Sitter space whose cosmological constant is minus the mass squared, the model effectively behaves like the massless theory in flat space: its degree of freedom disappears.     

Dirac Equation in Space–Time with Torsion

The Dirac equation in a curved space–time endowed with compatible affine connection is reconsidered. After a detailed decomposition of the total action, the equation is obtained by varying with respect to the Dirac spinor and the torsion field. The result is a known Dirac-like equation with constraints that can be interpreted as the equation of a self-interacting spin 1/2 particle in curved space–time. The scheme is then translated into the language of the 2-spinor formalism of curved space–time based on the choice of a null tetrad frame. The spinorial equation so obtained coincides with the standard one in case of no torsion, while in general it remains a nonlinear equation describing a self-interacting spin 1/2 particle. The nonlinearity is produced by the interaction of the particle with its own current that remains conserved as in the free torsion case.     

Rarita-Schwinger Quantum Free Field via Deformation Quantization

Rarita-Schwinger (RS) quantum free field is reexamined in the context of deformation quantization (DQ). It is interesting to consider this alternative for the specific case of the spin 3/2 field because DQ avoids the problem of dealing from the beginning with the extra degrees of freedom which appears in the conventional canonical quantization. It is found out that the subsidiary condition does not introduce any change either in the Wigner function or in other aspects of the Weyl-Wigner-Groenewold-Moyal formalism, such as: the Stratonovich-Weyl quantizer and normal ordering, in relation to de Dirac field case. The RS propagator is also calculated within this framework.     

Kaluza-Klein reduction and consistency of the massive spin-3/2 theory with external interaction

A gauge-invariant Rarita-Schwinger theory of a massive spin-3/2 particle interacting with external electromagnetic, gravitational and dilaton fields is obtained by Kaluza-Klein reduction of a massless Rarita-Schwinger theory with graviational interaction. Fermionic gauge invariance serves to determine the background equations of motion. The couplings with external fields obtained by the Kaluza-Klein reduction are shown to lead to the absence of the classical Velo-Zwanziger problem and on quantizing using Dirac's procedure, the field anticommutators are found to be positive definite.     

A Note on the Rarita-Schwinger Equations

Assuming that the background spacetime is a solution of the Einstein vacuum equations without cosmological constant, we analyze how the Rarita-Schwinger equations can be obtained via a particular generalization of the usual spin-3/2 massless free field equations. On the basis of this analysis we speculate on the possibility of finding other generalizations of the Rarita-Schwinger equations.     

Spin-3/2 fields in flat space-time

The equations for the spin-3/2 (Rarita-Schwinger) field given by linearized simple supergravity are written in space-plus-time form in terms ofSU(2) spinors, assuming that the background space-time is flat. Some consequences of these equations are analyzed and a Hamiltonian structure for the Rarita-Schwinger field is obtained.     

Elastic scattering of electrons by nuclei of half-integer spin and discrete symmetries

Analytical expression is obtained for the right-left asymmetry A _RL ^(3/2) for the process of elastic scattering of the longitudinally polarized electrons by nuclei with spin 3/2, described in the framework of Rarita-Schwinger formalism by invariant form factors of electromagnetic and weak vertex functions. It is shown, that this asymmetry directly depends on the nuclear anapole form factors G ₁ ⁽ⁿ⁾, and structurally is equivalent to asymmetry A _RL ^(1/2), which arises in electron scattering by proton.     

Second-order wave equation for spin-1/2 fields: 8-Spinors and canonical formulation

The algebraic structure of the 8-spinor formalism is discussed, and the general form of the 8-component wave equation, equivalent to the second-order 4-component one, is presented. This allows a canonical formulation that will be the first stage of the future Clebsch parametrization, i.e., a relativistic generalization of the Bohm-Schiller-Tiomno pioneering work on the Pauli equation.     

超子衰变产物的角分布

假设了一定的相互作用哈密顿量,计算了自旋为1/2。而服从狄拉克波动方程的粒子衰变产物的角分布,计算了自旋为3/2而服从赖列泰—许温格波动方程的粒子的衰变产物的角分布。讨论了宇称守恒相互作用和宇称不守恒相互作用强度之间的比例和不对称系数α的关系。指出利用费曼—盖尔曼的普适费米相互作用推导得的Λ超子衰变产物的角分布不对称因子和实验数值一致。指出假使在重正化以后矢量耦合和赝矢量耦合常数不再相等,那末不对称因子的数值可能有相当大的改变。因此准确测定α的数值有助于费曼—盖尔曼普适费米相互作用的重正化效应的研究。服从赖列泰—许温格波动方程,自旋为3/2的粒子衰变产物和实验上得到的的Λ超子衰变产物的角分布不可能符合。这和李政道和杨振宁的一般结论一致。     

Note on the massive Rarita-Schwinger field in the AdS/CFT correspondence

We consider a massive Rarita-Schwinger field on the Anti-de Sitter space and solve the corresponding equations of motion. We show that appropriate boundary terms calculated on-shell give two-point correlation functions for spin-3/2 fields of the conformal field theory on the boundary. The relation between Rarita-Schwinger field masses and conformal dimensions of corresponding operators is established.     

SL(2C) invariance of the gravitational field

The gravitational field equations of general relativity theory are cast into a Yang-Mills-type theory by use of the group SL(2,C). The spin coefficients take the rôle of the Yang-Mills-like potentials, whereas the Riemann tensor takes the rôle of the fields. Comparison of this formalism with that of Utiyama and Kibble who related invariance under the Lorentz and the Poincaré groups to the existence of the gravitational field, is discussedBased on a lecture given at the International Conference on Relativity and Gravitation, Copenhagen, July 1971.     

Massive Field Equations of Arbitrary Spin in Schwarzschild Geometry: Separation Induced by Spin-{{3\over2}} Case

The separation of variables of the spin- field equation is performed in detail in the Schwarzschild geometry by means of the Newman Penrose formalism. The separated angular equations coincide with those relative to the Robertson-Walker space-time. The separated radial equations, that are much more entangled, can be reduced to four ordinary differential equations, each in one only radial function. As a consequence of the particular nature of the spin coefficients it is shown, by induction, that the massive field equations can be separated for arbitrary spin. baselineskip=12 pt PACS 04.20.Cv- Fundamental problems and general formalism. PACS 03.65.Pm- Relativistic wave equations. PACS 02.30.Jr- Partial differential equations. PACS 04.20.Jb- Exact solutions.     

Canonical normal coordinates

We examine the advantages and disadvantages of fixing the coordinate gauge to be that of the Riemann normal coordinates by applying the Dirac formalism for constrained canonical systems in general relativity.     

Covariant,algebraic, and operator spinors

We deal with three different definitions for spinors: (I) thecovariant definition, where a particular kind ofcovariant spinor (c-spinor) is a set of complex variables defined by its transformations under a particular spin group; (II) theideal definition, where a particular kind of algebraic spinor (e-spinor) is defined as an element of a lateral ideal defined by the idempotente in an appropriated real Clifford algebra _p,q (whene is primitive we writea-spinor instead ofe-spinor); (III) the operator definition where a particular kind of operator spinor (o-spinor) is a Clifford number in an appropriate Clifford algebra _p,q determining a set of tensors by bilinear mappings. By introducing the concept of spinorial metric in the space of minimal ideals ofa-spinors, we prove that forp+q5 there exists an equivalence from the group-theoretic point of view among covariant and algebraic spinors. We also study in which senseo-spinors are equivalent toc-spinors. Our approach contain the following important physical cases: Pauli, Dirac, Majorana, dotted, and undotted two-component spinors (Weyl spinors). Moreover, the explicit representation of thesec-spinors asa-spinors permits us to obtain a new approach for the spinor structure of space-time and to represent Dirac and Maxwell equations in the Clifford and spin-Clifford bundles over space-time.