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Hawai'i physicists observe mysterious new particle in BESIII Experiment

University of Hawaiʻi at Mānoa
Frederick A. Harris, (808) 956-2940
Professor, Physics & Astronomy
Talia S Ogliore, (808) 956-4531
Public Information Officer
Posted: Apr 8, 2013

Beijing Spectrometer Detector (image by the BESIII Collaboration)
Beijing Spectrometer Detector (image by the BESIII Collaboration)
The charged charmonium-like structure at BESIII (image by the BESIII Collaboration)
The charged charmonium-like structure at BESIII (image by the BESIII Collaboration)
An international team of scientists that operate the Beijing Spectrometer (BESIII) Experiment at the Beijing Electron Positron Collider in China recently began a series of studies aimed at understanding the anomalous "Y(4260)" particle. As a striking and unexpected first observation from these new studies, the collaboration has reported that the Y(4260) particle in fact decays to a new, and perhaps even more mysterious, particle that they named the Zc(3900).

The University of Hawai‘i at Mānoa’s High Energy Physics Group in the department of Physics and Astronomy is part of the international collaboration that made this discovery. High energy physics involves the study of subatomic particles that are the building blocks of matter and the forces that act between them.

“The new observations challenge what was thought to be a well-understood system of possible configurations of charmed- and anti-charmed quarks, those that were considered to be among the simplest and most easily understood subatomic particles,” said Professor Frederick A. Harris, co-spokesperson for the experiment.

Recent discoveries of several new particles, including the Y(4260) and now the Zc(3900), suggest that more complex structures have to be considered.

A description of new particle was reported by the Chinese Academy of Sciences’ Institute of High Energy Physics and submitted to the scientific journal Physical Review Letters. It is available at at arXiv:1303.5949 (hep-ex).

The University of Hawai‘i at Mānoa joined the Beijing Spectrometer collaboration in 1993 and since then has had a strong impact on its research program. In particular, UHM has played a key role in developing a number of the critical instrumental components of the BESIII Experiment and its predecessor BESII. In 2010, UHM helped construct the beam energy measurement system for the Beijing electron-positron collider, improving the precision of BESIII’s particle measurements. Other contributions include the development and construction of a laser calibration system for the time-of-flight detector of BESIII, the construction of replacement endplates and the outer cylinder for the BESII main drift chamber (see UH press release, "Hawaiʻi-built drift chamber headed for Beijing accelerator"), and other components for BESII.

UHM has also made major contributions to analyses, including the current precision measurement of the mass of the tau lepton, which is a big brother of the electron. This is an important parameter of the standard model of elementary particle physics.

The BESIII Experiment research team is comprised of about 350 physicists from 50 institutions in 11 countries. U.S. groups include the University of Hawai‘i at Mānoa, Carnegie Mellon University, Indiana University, the University of Minnesota, and the University of Rochester.

Read the full text of the Chinese Academy of Sciences’ announcement here:

Researcher Contact:
Professor Frederick A. Harris, Phone (808) 956-2940, Email

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