Below is a single, combined markdown table for the invts (now dis_*) variables.
- Three columns:
- Variable (dis_*)
- Definition (code snippet or formula in plain text)
- Physical Meaning
- The Comments column is omitted per your request.
| Variable (dis_*) | Definition | Physical Meaning |
|---|---|---|
| Electron–Ion Invariants | ||
| twopdotk | 2 * PIncident_Vertex.Dot(kIncident_Vertex) | Scalar product (times 2) of ion 4-momentum and incident electron 4-momentum |
| s_e | MIon^2 + mElectron^2 + twopdotk | Total squared energy (Mandelstam s) of the electron–ion system |
| Virtual Photon | ||
| twopdotq | 2 * PIncident_Vertex.Dot(qVirtual_Vertex) | Scalar product (times 2) of ion 4-momentum and virtual photon 4-momentum |
| s_q | MIon^2 + twopdotq | Modified CM energy squared, replacing electron with virtual photon |
| Core DIS Kinematics | ||
| q2 | Q2 = Q2Max * uu + Q2Min * (1 - uu) | Negative four-momentum transfer squared (Q^2) of the virtual photon |
| xBj | xBj = (xMin)^(1 - uv) * (xMax)^(uv) | Bjorken-x, fraction of the target nucleon’s momentum carried by the struck quark |
| x_d | x_d = xBj * (MProton / MIon) | Rescaled x to account for the ion’s mass |
| y_d | y_d = q2 / (x_d * twopdotk) | Inelasticity parameter in ion-level kinematics |
| Yplus | 1 + (1 - y_d) * (1 - y_d) | Common DIS factor 1 + (1-y)^2 in the generator’s notation |
| Proton (Ion) Momentum | ||
| pDrest | sqrt( PIncident_Rest(0)^2 + PIncident_Rest(1)^2 + PIncident_Rest(2)^2 ) | Magnitude of the proton/ion 3-momentum in its own rest frame |
| Missing Mass | ||
| MX2 | PX_Vertex.M2() | Squared invariant mass of the unobserved (remaining) hadronic system |
| Spectator Kinematics | ||
| alphaS | ABeam * ( pS_rest * csThRecoil + pSpectator_Rest.E() ) / MIon | Light-cone momentum fraction of the spectator/recoil nucleon or baryon |
| pPerpS | pS_rest * sqrt( 1 - csThRecoil * csThRecoil ) | Transverse momentum of the spectator in the rest frame |
| Miscellaneous | ||
| nu | E_incident_e - E_scattered_e (or similar) | Energy transfer from the electron to the hadronic system |
| t_spectator, tprime | (p_in - p_recoil)^2, and tprime = t - t_min (not explicitly in snippet) | Momentum transfer to the spectator or “excess” above minimal t |
| tempvar | (placeholder variable) | Debug or intermediate quantity, often zero |
Units:
- Most energy and momentum quantities are in GeV, and squared forms (like s_e, s_q, q2, MX2) are in GeV^2.
- Dimensionless variables include xBj, x_d, alphaS, y_d, Yplus.
Notes:
- Variable naming in code was
invts.TwoPdotk, etc. You have them asdis_twopdotk, etc. - The definitions come directly from the MC generator snippet you provided.
- Variable naming in code was