ARGUS distribution

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ARGUS
Parameters cut-off (real)
curvature (real)
Support
PDF see text
CDF see text
Mean

where I1 is the Modified Bessel function of the first kind of order 1, and is given in the text.
Mode
Variance

In physics, the ARGUS distribution, named after the particle physics experiment ARGUS,[1] is the probability distribution of the reconstructed invariant mass of a decayed particle candidate[clarification needed] in continuum background[clarification needed].

Definition[edit]

The probability density function (pdf) of the ARGUS distribution is:

for 0 ≤ x < c. Here χ, and c are parameters of the distribution and

and Φ(·), ϕ(·) are the cumulative distribution and probability density functions of the standard normal distribution, respectively.

Differential equation[edit]

The pdf of the ARGUS distribution is a solution of the following differential equation:

Cumulative distribution function[edit]

The cumulative distribution function (cdf) of the ARGUS distribution is

.

Parameter estimation[edit]

Parameter c is assumed to be known (the speed of light), whereas χ can be estimated from the sample X1, …, Xn using the maximum likelihood approach. The estimator is a function of sample second moment, and is given as a solution to the non-linear equation

.

The solution exists and is unique, provided that the right-hand side is greater than 0.4; the resulting estimator is consistent and asymptotically normal.

Generalized ARGUS distribution[edit]

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

where Γ(·) is the gamma function, and Γ(·,·) is the upper incomplete gamma function.

Here parameters c, χ, p represent the cutoff, curvature, and power respectively.

The mode is:

p = 0.5 gives a regular ARGUS, listed above.

References[edit]

  1. ^ Albrecht, H. (1990). "Search for hadronic b→u decays". Physics Letters B. 241 (2): 278–282. Bibcode:1990PhLB..241..278A. doi:10.1016/0370-2693(90)91293-K.  (More formally by the ARGUS Collaboration, H. Albrecht et al.) 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.

Further reading[edit]

  • Albrecht, H. (1994). "Measurement of the polarization in the decay B → J/ψK*". Physics Letters B. 340 (3): 217–220. Bibcode:1994PhLB..340..217A. doi:10.1016/0370-2693(94)01302-0. 
  • Pedlar, T.; Cronin-Hennessy, D.; Hietala, J.; Dobbs, S.; Metreveli, Z.; Seth, K.; Tomaradze, A.; Xiao, T.; Martin, L. (2011). "Observation of the hc(1P) Using e+e Collisions above the DD Threshold". Physical Review Letters. 107 (4). arXiv:1104.2025free to read. Bibcode:2011PhRvL.107d1803P. doi:10.1103/PhysRevLett.107.041803. 
  • Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D. N.; Hooberman, B.; Kerth, L. T.; Kolomensky, Y. G.; Lynch, G.; Osipenkov, I. L.; Tanabe, T.; Hawkes, C. M.; Soni, N.; Watson, A. T.; Koch, H.; Schroeder, T.; Asgeirsson, D. J.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; Barrett, M. (2010). "Search for Charged Lepton Flavor Violation in Narrow Υ Decays". Physical Review Letters. 104 (15): 151802. arXiv:1001.1883free to read. Bibcode:2010PhRvL.104o1802L. doi:10.1103/PhysRevLett.104.151802. PMID 20481982.