Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review

The Intrinsic Parity of Elementary Particles

G. C. Wick, Arthur S. Wightman, Eugene Paul Wigner

Published Oct 1, 1952• 666 citations
Publisher

Abstract

The limitations to the concept of parity of quantum-mechanical states and, in particular, of intrinsic parity of elementary particles are discussed. These limitations are shown to follow from "superselection rules," i.e., from restrictions on the nature and scope of possible measurements. The existence of such superselection rules is proved for the case of spinor fields; it is also conjectured that a superselection rule operates between states of different total charge.

DOI
10.1103/physrev.88.101

Related papers

Analysis of the Experimental Meaning of Coherent Superposition and the Nonexistence of Superselection Rules

Ronald Mirman

The experimental meaning of coherent superposition of state vectors is analyzed. It is shown that the involvement of the measuring instrument is of basic importance and that it is erroneous to study superposition without it. From this analysis it is found that there are no such things as superselection rules. The meaning of the sign change of spinors under $2\ensuremath{\pi}$ rotation is considered, and it is found to have experimental consequences. The nonmeasurability of the relative parity of states with different $z$ components of angular momentum is shown. An appendix discusses the application of some of the considerations of the paper to decaying states and elementary particles.

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields•Jun 15, 1970•26 citations

Limitations on the superposition principle: superselection rules in non-relativistic quantum mechanics

C. Cisneros, R. P. Martı́nez-y-Romero, H. N. Núñez‐Yépez +1 more

The superposition principle is a very basic ingredient of quantum theory. What may come as a surprise to many students, and even to many practitioners of the quantum craft, is tha superposition has limitations imposed by certain requirements of the theory. The discussion of such limitations arising from the so-called superselection rules is the main purpose of this paper. Some of their principal consequences are also discussed. The univalence, mass and particle number superselection rules of non-relativistic quantum mechanics are also derived using rather simple methods.

arXiv:quant-ph/9809059•European Journal of Physics•May 1, 1998•25 citations

The Trouble with Superselection Accounts of Measurement

Mariam Thalos

A superselection rule advanced in the course of a quantum-mechanical treatment of some phenomenon is an assertion to the effect that the superposition principle of quantum mechanics is to be restricted in the application at hand. Superselection accounts of measurement all have in common a decision to represent the indicator states of detectors by eigenspaces of superselection operators named in a superselection rule, on the grounds that the states in question are states of a so-called classical quantity and therefore not subject to quantum interference effects. By this strategy superselectionists of measurement expect to dispense with use of projection postulates in treatments of measurement. I shall argue that superselection accounts of measurement are self-contradictory, and that treatments of infinite systems, if they can avoid the contradiction, are not true superselection accounts.

Philosophy of Science•Sep 1, 1998•2 citations

Charge Superselection Rule

Yakir Aharonov, Leonard Susskind

Questions concerning superselection rules are considered. Two experiments are discussed. In the first, coherent superpositions of different angular-momentum states are constructed. In the second, coherent superpositions of states with different charge are constructed in complete analogy with the angular-momentum case. We suggest that, contrary to a widespread belief, interference may be possible between states with different charges.

Physical Review•Mar 25, 1967•242 citations

Nonlocality in the presence of superselection rules

Frank Verstraete, Norbert Schuch, J. I. Cirac

Effective superselection rules severely alter the possible operations that can be implemented on a distributed quantum system. Superselection rules appear in e.g. the context of experiments with entangled cold gases: in this case all local operations have to conserve the local particle number. These superselection rules enforces us to reconsider the notion of nonlocality, as the new constraint implies limitations on the local operations that can be implemented. This gives rise to a novel form of nonlocality, and it is possible to associate a new nonlocal resource to it. In this paper we characterize this new resource, quantify it and discuss some applications.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 25, 2004•1 citation

Critical Comment on the Nonexistence of the Charge Superselection Rule

Yasuo Yoshihuku

Aharonov and Susskind denied the concept of the superselection rules, and suggested the experimental feasibility of measuring interference between states with different charges. Their reasoning is shown to be incorrect.

Progress of Theoretical Physics•Jun 1, 1972•1 citation
The limitations to the concept of parity of quantum-mechanical states and, in particular, of intrinsic parity of elementary particles are discussed. These limitations are shown to follow from "superselection rules," i.e., from restrictions on the nature and scope of possible measurements. The existence of such superselection rules is proved for the case of spinor fields; it is also conjectured that a superselection rule operates between states of different total charge.
The experimental meaning of coherent superposition of state vectors is analyzed. It is shown that the involvement of the measuring instrument is of basic importance and that it is erroneous to study superposition without it. From this analysis it is found that there are no such things as superselection rules. The meaning of the sign change of spinors under $2\ensuremath{\pi}$ rotation is considered, and it is found to have experimental consequences. The nonmeasurability of the relative parity of states with different zzz components of angular momentum is shown. An appendix discusses the application of some of the considerations of the paper to decaying states and elementary particles.
The superposition principle is a very basic ingredient of quantum theory. What may come as a surprise to many students, and even to many practitioners of the quantum craft, is tha superposition has limitations imposed by certain requirements of the theory. The discussion of such limitations arising from the so-called superselection rules is the main purpose of this paper. Some of their principal consequences are also discussed. The univalence, mass and particle number superselection rules of non-relativistic quantum mechanics are also derived using rather simple methods.
A superselection rule advanced in the course of a quantum-mechanical treatment of some phenomenon is an assertion to the effect that the superposition principle of quantum mechanics is to be restricted in the application at hand. Superselection accounts of measurement all have in common a decision to represent the indicator states of detectors by eigenspaces of superselection operators named in a superselection rule, on the grounds that the states in question are states of a so-called classical quantity and therefore not subject to quantum interference effects. By this strategy superselectionists of measurement expect to dispense with use of projection postulates in treatments of measurement. I shall argue that superselection accounts of measurement are self-contradictory, and that treatments of infinite systems, if they can avoid the contradiction, are not true superselection accounts.
Effective superselection rules severely alter the possible operations that can be implemented on a distributed quantum system. Superselection rules appear in e.g. the context of experiments with entangled cold gases: in this case all local operations have to conserve the local particle number. These superselection rules enforces us to reconsider the notion of nonlocality, as the new constraint implies limitations on the local operations that can be implemented. This gives rise to a novel form of nonlocality, and it is possible to associate a new nonlocal resource to it. In this paper we characterize this new resource, quantify it and discuss some applications.