Observables

Warning: The list of observables below was inherited from the old HepData site and may not be up-to-date.

HEPData Observables

Observables describe the quantity that is being measured. They are used in searching and are a simplified form of the dependent variable name (yname). Thus they do not have units and are fairly broad in their scope. The table below shows the most commonly used observable names together with a list of independent variable names (xnames) as used in HEPData. When necessary more detailed descriptions are given by clicking on the 'more'.

multiplicity measurements....less
MULT2 etc.. are the second etc.. moments
of the multiplicity distributions

Observables		xnames (to be used with differential distributions)
-		an xname prefixed with 'D' signifies a difference in two variables (eg DYRAP)
Observable	Description	xname	Description
SIG	integrated cross section....more integrated cross section....less SIG is the observable name for a cross section. On its own it signifies a total or integrated cross section. In combinations with D, or Dg etc. it is used in the differential cross section as shown below.	M MT E ET EKIN P PT, PT**2 PL XL XT X THETA OMEGA PHI T TP YRAP ETARAP S W Q, Q**2 Y Z CENTRALITY THRUST MINOR MAJOR SPHERICITY PLANARITY APLANARITY OBLATENESS HEAVY-JET-MASS LIGHT-JET-MASS WIDE-JET-BROADENING TOTAL-JET-BROADENING C-PARAMETER D-PARAMETER PTIN PTOUT	mass transverse mass energy transverse energy kinetic energy momentum transverse momentum (squared) longitudinal momentum Feynman X transverse X X (in DIS) polar angle solid angle azimuthal angle momentum transfer momentum transfer prime rapidity pseudorapidity invariant mass squared energy of system of particles virtual momentum transfer (squared) inelasticity (in DIS) energy/momentum fraction centrality JET SHAPES thrust thrust minor thrust major sphericity planarity aplanarity oblateness heavy jet mass light jet mass wide jet broadening total jet broadening C-parameter D-parameter momentum projection in the event plane momentum projection transverse to the event plane
SIG/SIG, RATIO, N/N	ratio of cross sections/distributions....more ratio of cross sections/distributions....less These are used to signify the measurement is of a ratio of cross sections or other equvalent distributions.
DSIG/Dxname	single differential cross section
D2SIG/Dxname/Dxname	double differential cross section
D3SIG/Dxname/Dxname/Dxname	triple differential cross section
E*D3SIG/DP**3	invariant cross section
N	number of events
DN/Dxname	single differential distribution
D2N/Dxname/Dxname	double differential distribution
D3N/Dxname/Dxname/Dxname	triple differential cross distribution
MULT, DISPERSION, MULT2 etc..	multiplicity measurements....more
POL, POL.POL, POL.POL.POL	single, double and triple spin polarisations
ASYM	asymmetry measurement
F1, F2, XF3, FL	structure functions
A1, A2, G1, G2	spin asymmetries and structure functions
V1, V2, V3, V4, V5, V6	azimuthal asymmetries (Fourier Coefficients)
V11, V22, V33, V44, V55, V66	azimuthal asymmetries (Fourier Coefficients)
ACC, EFF	acceptance, efficiency measurements
CLS	confidence limits
WIDTH	Measurement of a width
RCORR, CORR	(ratio of) correlation measurements
EEC, AEEC	energy-energy correlation and its asymmetry
PSI	Jet Shape (integrated)
RHO	density matrix element....more density matrix element....less also used for jet density distributions
POL.RHO	density matrix element with a ....more density matrix element with a ....less polarized photon beam
SLOPE, POWER	exponential slope/power of a fit
ALPHAS, SIN2TW	alpha-s, sin^2(theta-w)
GA, GV	axial-vector couplings
FORMFACTOR	Form Factor measurements
CONST	Measurement of a physical constant
RAA, RPA, RCP	nuclear modification factors
LEG, LEGN, LEGP, LEGPN	Legendre Coefficients (somewhat historical)....more Legendre Coefficients (somewhat historical)....less Legendre coefficients of fit to the DSIG/DOMEGA distributions LEGN is normalised LEGP is for P*DSIG/DOMEGA
YLM	Ylm moment (somewhat historical)
AMP, REAMP/IMAMP, PHASE	amplitude, real/imaginary ratio, phase (somewhat historical)