Melting Upsilon (IMAGE) DOE/Brookhaven National Laboratory Caption In the presence of quark-gluon plasma (background), free quarks and gluons can get in the way of the interaction between the bottom quark and antibottom quark that make up an upsilon. This screening of the quark-antiquark interaction causes the upsilon to dissociate, or melt. The data show that loosely bound upsilons melt most easily, while the tightly bound ground state melts the least. Credit Brookhaven National Laboratory Usage Restrictions OK for use with stories about this research. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.