Strange, stranger and strangest

The plot is proportional to the probability (invariant differential cross section) of observing lambda, cascade and omega particles as a function of their transverse momentum. The solid lines are fitted curves to the power law function (A(pT+1.3)-n) and n~8.5 for all three particles. The insert shows the ratios of cascades to lambdas and omega to lambdas.

While physicists have learned a lot of about our world on a fundamental scale, there are still things that remain a mystery. One of those is how hadrons are produced from particle interactions. Hadrons are composite objects made up of quarks and held together by the strong force. Hadrons vary in shape and size and their composition is based on the combination of quarks inside. Physicists still do not understand how nature chooses to produce one type of composite object over another in a proton-antiproton collision.

To try to help shed light on this issue, physicists at CDF have been investigating the properties of three specific objects, namely the lambda, cascade and omega particles. A detailed analysis of production properties of particles containing different quark flavors and different numbers of quarks could pave the way to understanding the process from a theoretical underpinning in the Standard Model. The lambda, cascade and omega particles each comprise of three quarks and respectively contain one, two and three strange quarks. These particles are short lived, with lifetimes less than a billionth of a second. Amazingly, even with such a fleeting existence, these particles can be studied by physicists.

CDF physicists measured the differential cross section for each particle – how often each particle is produced as a function of the particle’s momentum. They observed (see figure, above) that as the transverse momentum increases, the slopes of the transverse differential cross sections of the three particles are similar to each other and to those of mesons such as Kshorts and pions. This could indicate a universal principle of particle production. Our next step is to study the particle production in jets and check if this observation continues to hold.

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— Edited by Andy Beretvas

These physicists from Duke University were responsible for this analysis.