massive particle

Mass qualification

Qualification requires positive invariant mass; total energy or a positive upper bound alone does not establish this.

1. Does the reported quantity represent invariant mass, rest energy, a mass bound, or an effective parameter? definition
2. What measurement or established species assignment supports m > 0, and with what uncertainty? measurement

Entity and species

An elementary particle, a composite particle, and an unbound multiparticle system require different identity claims even when each has a positive invariant mass.

1. Is this an elementary particle, a composite particle, or a multiparticle system being treated collectively? boundary
2. Which species model supplies the identity, and what evidence supports that assignment? provenance

On-shell kinematics

For a free on-shell particle, invariant mass is related to energy and momentum by E² − p²c² = m²c⁴.

1. In which reference frame were energy and momentum measured, and what are their uncertainties and correlations? measurement
2. Is the free on-shell description justified, or is this a bound-state constituent, virtual contribution, or medium-dependent excitation? boundary

Motion regime

Massive free-particle kinematics permits a rest frame; the ratio of momentum to mc determines whether nonrelativistic approximations are suitable.

1. What values of β and Lorentz factor follow from the measured momentum and assigned mass? measurement
2. Does the required precision permit a nonrelativistic approximation, or must the agent use relativistic relations? action

Coupling and response

Charge, spin, and species-specific couplings determine possible responses to fields and matter.

1. Which interaction quantum numbers and couplings are established for this particle or candidate? definition
2. Which proposed field or material interactions are supported by those properties? action

Accessible processes

Production requires sufficient invariant energy and compatible conservation laws; observation depends on interaction signatures or decay products.

1. Does the proposed initial state have sufficient invariant energy and compatible conserved quantities to produce the particle? action
2. Which signature would identify it: a track, energy deposition, time of flight, decay reconstruction, or missing four-momentum? measurement

Survival and products

Lifetime evidence and decay-channel information determine whether to model propagation, prompt decay, or a stability limit.

1. Is the proper lifetime measured, bounded, or unknown, and what supports any claim of stability? measurement
2. Which decay channels are established, and how do the measured boost and lifetime affect the expected observation location? action

Composite mass accounting

A composite particle's invariant mass reflects total rest-frame energy and cannot generally be obtained by adding isolated constituent masses alone.

1. Is the mass assigned to the whole composite particle or to one constituent within it? boundary
2. How are binding and internal energy represented when relating composite mass to constituent properties? definition

Mass inference

An inferred mass depends on the observables and analysis used; an unresolved result must remain distinguishable from evidence of positive mass.

1. Which source and method produced the mass estimate or bound? provenance
2. Which calibration, background, resolution, or theoretical assumptions materially affect the conclusion? measurement

Mass-state interpretation

A single sharp mass may be inadequate for a superposition of mass eigenstates or an unstable resonance; the applicable state and mass convention must be explicit.

1. Does the description concern a definite mass eigenstate, a superposition, or an unstable resonance? definition
2. What state decomposition, mass convention, or width information is needed before applying single-mass kinematics? boundary

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of massive particle this model covers, and on what evidence? provenance

Kinds and varieties

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these kinds and varieties hold for the sense of massive particle this model covers, and on what evidence? provenance

Identifiers and schemes

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these identifiers and schemes hold for the sense of massive particle this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of massive particle this model covers, and on what evidence? provenance

Typical measurements

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these typical measurements hold for the sense of massive particle this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of massive particle this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of massive particle this model covers, and on what evidence? provenance