ARGUS distribution

In physics, the ARGUS distribution, named after the particle physics experiment ARGUS [ARGUS Collaboration, H. Albrecht, Phys. Lett. B 241, 278 (1990). In this paper, the function has been defined with parameter "c" representing the beam energy and parameter "p" set to 0.5. The normalization and the parameter χ have been obtained from data.] , is the probability distribution of the reconstructed invariant mass of a decayed particle candidate in continuum background. Its probability density function (not normalized) is:

: $f(x)=xcdotsqrt\{1-left(frac\{x\}\{c\}\; ight)^2\}expleft\{-chicdotleft(1-left(frac\{x\}\{c\}\; ight)^2\; ight)\; ight\}\; ext\{\; for\; \}x>0.$

Sometimes a more general form is used to describe a more peaking-like distribution:

: $f(x)=xcdotleft\; [1-left(frac\{x\}\{c\}\; ight)^2\; ight]\; ^pexpleft\{-chicdotleft(1-left(frac\{x\}\{c\}\; ight)^2\; ight)\; ight\}$

Here parameters "c", χ, "p" represent the cutoff, curvature, and power ("p" = 0.5 gives a regular ARGUS) respectively.

References