quark
Enable an AI agent to recognise a quark description, assess what its inferred physical state supports, and select valid analyses or interaction models.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise a quark description, assess what its inferred physical state supports, and select valid analyses or interaction models.
A quark is an elementary fermion of the Standard Model that carries color charge, fractional electric charge, and baryon number, and is confined by QCD into hadrons rather than observed as a free particle at ordinary energies.
It can be Check a proposed quark identity against flavour, charge, spin and colour representation.; Associate a quark hypothesis with hadron content, a hard process or reconstructed decay evidence.; Compare kinematic or mass estimates only after reconciling definitions, scales and uncertainties.; Evaluate proposed production and transition channels against conservation laws and interaction assumptions.; Select a context-appropriate calculation, simulation or tagging method and report its applicability limits.; Revise or reject an assignment when evidence cannot distinguish a quark from alternative partonic or hadronic explanations..
Distinguishing features
Require a supported assignment to up, down, strange, charm, bottom or top flavour; 'parton' alone does not distinguish a quark from a gluon. [CERN quark glossary](https://opendata.cern.ch/glossary/Quark)
Check fractional electric charge against flavour and particle or antiparticle designation: quarks have +2/3 or -1/3 in elementary-charge units, with opposite signs for antiquarks. [CERN quark glossary](https://opendata.cern.ch/glossary/Quark)
Require consistency with a spin-1/2 colour-triplet quark, or colour-antitriplet antiquark, rather than a colourless lepton or a spin-1 gluon.
Distinguish the inferred quark from its containing hadron or associated jet; an isolated detector track is insufficient evidence for a free quark. [CERN ALICE overview](https://home.cern/science/experiments/alice/)
Scope
+ Quark flavour, particle or antiparticle designation, and identifying quantum numbers
+ Quark assignments within hadrons, scattering processes, simulations and strongly interacting media
+ Kinematics and mass parameters with their reference frame, scale and theoretical interpretation
+ Quark-specific production, interaction, hadronisation and decay constraints
+ Evidence supporting quark identification and limits on attributing observables to individual quarks
- Whole-hadron identity, spectrum and internal structure, owned by hadron models
- Gluon and electroweak-boson identity and state
- Jet reconstruction and detector operation as independently managed systems
- Bulk thermodynamic properties of quark-gluon plasma
- Complete collision-event descriptions and accelerator operation
Characteristics
- Flavour assignment
- up | down | strange | charm | bottom | top | unresolved; retain competing hypotheses Determines which charge, mass and interaction descriptions can apply.
- Particle or antiparticle assignment
- quark | antiquark | unresolved Controls charge signs, colour representation and interpretation of production or decay channels.
- Electric charge
- Elementary-charge units e; distinguish inferred quantum-number assignment from a measured estimator Checks identity consistency and charge conservation without treating jet charge as exact quark charge.
- Spin description
- Spin quantum number 1/2; optional polarisation or helicity description with basis and uncertainty Separates species-level spin from a process-dependent spin state.
- Colour description
- Triplet | antitriplet; optional simulation colour-flow labels with convention Supports strong-interaction modelling without presenting a basis-dependent colour label as a directly measured property.
- Physical or modelling context
- Hadron constituent | hard-process parton | shower parton | medium excitation | reconstructed hypothesis Determines which individual-quark properties and operations are meaningful.
- Containing or associated system
- Links to hadron, collision process, medium, jet or decay hypothesis; specify relation type Prevents confusing containment, ancestry and observational association.
- Four-momentum assignment
- Energy in GeV and momentum components in GeV/c; frame, reconstruction level and uncertainty required Supports kinematic reasoning while exposing dependence on reconstruction or simulation.
- Mass parameter
- GeV/c^2; mass definition, renormalisation scheme and scale where applicable Prevents comparison of running, pole, constituent and generator parameters as interchangeable measurements.
- Inference status
- Species property | theoretical assignment | generator record | experimentally inferred candidate; confidence with calibration context Controls whether an agent may assert identity, compare hypotheses or only report an unresolved interpretation.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 11 findings · 30 questions.
Flavour and quantum identity Record what makes an assignment a particular quark species rather than another particle.
An agent needs a coherent identity before applying quark-specific state or interaction rules.
Flavour and conjugation
Separate species identity from particle or antiparticle designation.
Supported flavour assignment
Record a resolved flavour or explicit alternatives, together with whether the assignment denotes a quark or antiquark.
- Which quark flavour and particle or antiparticle designation are asserted, and which remain unresolved? definition
- Does this assignment come from a theoretical species definition, generator ancestry or experimental flavour evidence? provenance
Quantum-number consistency
Check the identifying quantum numbers without confusing intrinsic properties with measured proxies.
Compatible charge, spin and colour
Require a consistent charge, spin and colour representation, while distinguishing spin-state estimates and colour-flow conventions from species properties.
- Are electric charge, spin and colour representation consistent with the proposed flavour and conjugation? definition
- Which stated properties are inferred from identity, and which have independently measured estimators? measurement
- Would the same evidence also support a lepton, gluon or composite-hadron interpretation? boundary
Confinement and description context Record where a quark description applies and what its containing or associated system permits an agent to infer.
A quark assignment cannot be handled as an ordinary independently observable object.
Hadronic and medium context
Locate the quark description within a hadron or interacting medium.
Constituent role and environment
Record whether the description concerns valence content, sea contributions or an effective medium excitation, rather than assigning every context a persistent individual constituent.
- Is the quark described as valence content, a sea contribution or an excitation in a strongly interacting medium? definition
- Which hadron or medium model supplies the environment and the approximation used? provenance
- Does the description support an individual quark state, or only flavour content or a statistical distribution? boundary
Partonic description limits
Bound the interpretation of quarks represented in calculations and event records.
Parton stage and identity limits
Distinguish hard-process and shower assignments from observable final particles, and retain the conventions behind any ancestry relation.
- At which calculation or generator stage is this quark assignment defined? definition
- What resolution scale, factorisation assumptions or event-record conventions make that assignment meaningful? boundary
- May an agent follow the assignment across stages, or must it preserve a probabilistic or convention-dependent association? action
Kinematics and mass interpretation Make quantitative quark-state assertions interpretable and comparable.
Quark momentum and mass values can depend materially on the theoretical description and inference procedure.
Momentum and virtuality
Qualify assigned kinematics by reference frame and modelling level.
Qualified four-momentum
Record momentum, uncertainty and any on-shell or virtuality assumptions without silently substituting jet or hadron kinematics.
- What four-momentum is assigned, in which frame, and with what uncertainty or distribution? measurement
- Is it a parton-level value, a reconstructed estimate or a proxy taken from an associated jet or hadron? provenance
- Which on-shell or off-shell assumptions constrain the use of this momentum? boundary
Mass definition and scale
Preserve the meaning of a quoted quark mass.
Interpretable mass parameter
Attach the mass definition and relevant scale to a quoted value, preserving distinctions between field-theory, effective and generator parameters.
- Which mass definition is used, with what value, uncertainty, scheme and applicable scale? measurement
- Is this a running mass, pole mass, constituent-model parameter or generator parameter? definition
- What justified conversion or matching procedure is required before comparing it with another mass value? action
Interaction and fate Describe which quark processes can be evaluated and how the quark assignment terminates or changes.
An agent must distinguish an allowed interaction from an observable final state and handle flavour-specific evolution.
Production and flavour transitions
Constrain proposed production and interaction channels.
Channel admissibility
Evaluate proposed channels using the stated interaction model, initial state, available energy and relevant conservation constraints.
- Which production, scattering or flavour-changing channel is proposed, and under which interaction model? definition
- Are its charge balance, energy requirements and other applicable quantum-number constraints satisfied? boundary
- Which calculation and parameter inputs are needed before an agent can estimate a rate or branching probability? action
Hadronisation and decay
Distinguish hadron formation from quark-level decay and reconstructed descendants.
Flavour-dependent fate
Record the applicable hadronisation or decay treatment; top quarks decay before hadronising and require a distinct reconstruction path. [ATLAS top-quark overview](https://atlas.cern/updates/feature/top-quark)
- Does the assigned flavour and environment require hadronisation modelling, quark-level decay modelling or an explicitly coupled treatment? boundary
- Does a quoted lifetime or decay width belong to the quark description or to a containing hadron? measurement
- Which descendants or hadronisation products may be linked to this assignment, with what modelling uncertainty? action
Observable evidence and inference Connect quark assertions to measurable signatures and control how strongly an agent may act on them.
Quark identification usually depends on interpreting composite final states rather than observing a quark directly.
Signatures and alternatives
Record the observables and competing explanations behind an assignment.
Evidence for quark assignment
Identify the measured signatures supporting a quark or flavour interpretation, retaining backgrounds and ambiguity between quark and gluon origins.
- Which measured signatures support the assignment, such as displaced vertices, identified hadrons, decay reconstruction or scattering distributions? measurement
- Which dataset, analysis and reconstruction procedure produced those signatures? provenance
- Which alternative flavours, gluon processes or hadronic backgrounds remain compatible with the evidence? boundary
Calibration and permitted use
Translate evidence quality into justified analytical actions.
Assignment strength and use
Preserve tagging calibration, selection dependence and model uncertainty so that a candidate label does not become an unjustified certainty.
- What efficiencies, mistag rates, uncertainty estimates and validation domain accompany the assignment? measurement
- Is a reported score a calibrated probability, a discriminant or a generator label? definition
- Does the evidence justify selecting a flavour-specific analysis, retaining several hypotheses or withholding a resolved assignment? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- up quark (u)
- down quark (d)
- charm quark (c)
- strange quark (s)
- top quark (t)
- bottom quark (b)
- antiquark
- valence vs sea quark
- Which of these kinds and varieties hold for the sense of quark this model covers, and on what evidence? provenance
Sources
- Quark (Review of Particle Physics) - Masses, charges, generations, and Standard Model quantum numbers of the six quark flavors.
- The Standard Model - quarks - CERN public description of quarks as confined constituents of hadrons.
What the second pass must settle
- Does the registry intend antiquarks to be represented within vr.tr.quark or through a neighbouring entry linked by charge conjugation?
- Which levels of description must the first implementation support: species properties, event-level partons, hadron constituents or medium excitations?
- Which authoritative mass references, schemes and conversion procedures should govern comparisons for each flavour?
- What evidence and calibration thresholds should permit an agent to promote a flavour candidate to an accepted assignment in each supported analysis context?
- How should the model represent colour correlations and ambiguous parton ancestry without implying directly observable colour labels or persistent individual-quark identity?