Multidimensional HBT correlations in proton-antiproton collisions at root(s) = 630 GeV

TL;DR

This paper investigates the limitations of common models in fitting multidimensional HBT correlations in proton-antiproton collisions at 630 GeV, revealing a persistent unexplained peak at small momentum differences.

Contribution

It demonstrates the inadequacy of standard fit functions for HBT correlation data and explores alternative models, highlighting the need for new approaches.

Findings

Standard models fail to fit the data accurately.

A prominent unexplained peak exists at small momentum differences.

More complex models still do not provide a definitive fit.

Abstract

We analyse second moments $R_2$ of like-sign pion pairs in the two-dimensional $(q_L,q_T)$ and three-dimensional $(q_O,q_S,q_L)$ decompositions of the three-momentum difference. Conventional fit parametrisations such as gaussian, exponential, power-law and Edgeworth fail miserably, while more elaborate ones such as Levy do well but fail to yield a unique best-fit solution. A two-component model using a hard cut to separate small- and large-scale parts appears possible but not compelling. In all cases, the data exhibits a strong and hitherto unexplained peak at small momentum differences which exceeds current fits.