How Can Strange Quark Matter Occur Deeply in the Atmosphere?

We assess the fragmentation of strange quark matter in astrophysical events, showing that the application of statistical multifragmentation models suggests that most of the fragments (strangelets) should belong to an unstable baryon number $A$. While there are some caveats to be addressed, the flux of strangelets onto the Earth could be orders of magnitude lower than previous estimates, with negative prospects for the ongoing search experiments.

3-flavor quark matter (strange quark matter; SQM) can be stable or metastable for a wide range of strong interaction parameters. If so, SQM can play an important role in cosmology, neutron stars, cosmic ray physics, and relativistic heavy-ion collisions. As an example of the intimate connections between astrophysics and heavy-ion collision physics, this Chapter gives an overview of the physical properties of SQM in bulk and of small-baryon number strangelets; discusses the po...

Recently new data from the Cosmo-LEP project appeared, this time from DELPHI detector. They essentially confirm the findings reported some time ago by ALEPH, namely the appearence of bundles of muons with unexpectedly high multiplicities, which so far cannot be accounted by present day models. We argue, using arguments presented by us some time ago, that this phenomenon could be regarded as one more candidate for the presence in the flux of cosmic rays entering the Earth's at...

Our knowledge on the possible existence in nature of stable exotic particles depends solely upon experimental observation. Guided by this general principle and motivated by theoretical hypotheses on the existence of stable particles of strange quark matter, a variety of experimental searches have been performed. We provide an introduction to the theoretical hypotheses, an overview of the past searches, and a more detailed description of a recent search for helium-like strange...

After a brief introduction to the physics of bulk strange quark matter (SQM) this review focuses on the properties of low baryon number strangelets presently searched for in ultra-relativistic heavy-ion experiments at CERN and Brookhaven. Shell-model calculations reveal interesting (meta)stability properties in the experimentally accessible regime. A liquid drop model (Fermi-gas model) is shown to explain the overall behavior of the mode-filling calculations, leading to a phy...

It has been over 30 years since the first suggestion that the true ground state of cold hadronic matter might be not nuclear matter but rather strange quark matter (SQM). Ever since, searches for stable SQM have been proceeding in various forms and have observed a handful of interesting events but have neither been able to find compelling evidence for stable strangelets nor to rule out their existence. I will survey the current status and near future of such searches with par...

We discuss the possible imprints of strangelets (i.e., lumps of Strange Quark Matter) in Chacaltaya experimental data using model of propagation of such objects through the atmosphere developed by us recently.

Astrophysical bounds on the properties and abundances of primordial quark nuggets and cosmic ray strangelets are reviewed. New experiments to search for cosmic ray strangelets in lunar soil and from the International Space Station are described. Analogies with baryonic and supersymmetric Q-balls are briefly mentioned, as are prospects for strangelets as ultra-high energy cosmic rays.

We discuss the first-order phase transition of QCD at high temperature in the universe and the possible formation of quark-matter lumps through cooling in regions of increased pressure. We show tha similarity of results using confinement and breaking of chiral symmetry. The inclusion of strange matter may give stability to small drops, or strangelets, in the colour-flavour locked phase possibly achieved in neutron stars that could reach a high-altitude observatory like that o...

The galactic propagation of cosmic ray strangelets is described and the resulting flux is calculated for a wide range of parameters as a prerequisite for strangelet searches in lunar soil and with an Earth orbiting magnetic spectrometer, AMS-02. While the inherent uncertainties are large, flux predictions at a measurable level are obtained for reasonable choices of parameters if strange quark matter is absolutely stable. This allows a direct test of the strange matter hypothe...