Use of cumulants to quantify uncertainties in the HBT measurements of the homogeneity regions

Let us denote p(x|K) the space density of the points where identical particles of some kind, e.g. pi+ mesons, with momentum K are produced. When using the HBT method to determine p(x|K) one encounters ambiguities. We show that these ambiguities do not affect the even cumulants of the distribution p(x|K). In particular, the HBT radii of the homogeneity regions, which are given by the second order cumulants, and the distribution of distances between the pairs of production points for particles with momentum K can be reliably measured. The odd cumulants are ambiguous. The are, however, correlated. In particular, when the average position (K) is known as a function of K there is no further ambiguity.Comment: LateX, 10 pages, no figure

Ambiguities in the HBT approach to determine the interaction regions

The necessary and sufficient condition for a quantity to be measurable by the HBT method is given and discussed.Comment: Report at the conference QCD08, July 2008, LateX 8 pages, no figure

Missile Defence: A View from Turkey. CEPS Commentaries, 12 October 2009

On September 9th, the United States announced that it was planning a multi-billion dollar sale of 13 Patriot fire units, 72 PAC-3 missiles and a range of related hardware for ground-based air defence to Turkey. The decision, some commentators reasoned, was evidence that the US was turning to Turkey as an alternative base for the missile defence system (MDS) originally planned in Central Europe. Such assessments proved somewhat off the mark, however. What is on sale to the Turks (a system to protect Turkey against short- and medium-range missiles), it turns out, is different from what had been on offer to the Czechs and Poles, which was a system designed to intercept intercontinental ballistic missiles. The announced sale of one system, however, signalled the end of the other. On September 17th, the Obama administration confirmed it would abandon plans for an MDS based in Poland and the Czech Republic. In this Commentary, journalist and researcher Piotr Zalewski (Istanbul) assesses the implications of this move for Turkish-US relations and their neighbours and allies