Tue, Jul 24, 2001 page1

• Taiwan contributes to key research

  PARTICLE PROJECT Local physicists have contributed to a multinational project that might help answer one of the trickiest questions ever to face particle physicists

  • By Chiu Yu-Tzu / STAFF REPORTER WITH AGENCIES
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  Taiwan has become an influential contributor to a new discovery that seeks to answer questions concerning the birth of the universe, physicists said yesterday.

  Following two-and-half years of scientific research in Japan, carried out by 300 physicists from 14 countries, including Taiwan, scientists have found evidence of an existing phenomenon of lopsidedness in nature. This phenomenon will help scientists better understand why the universe contains matter rather than just empty space.

  Yesterday, physicists involved in the experiment announced their discovery simultaneously in Taipei, Tokyo, and Rome. Their research paper was officially introduced at Lepton Photon 2001, the 10th International Symposium on Lepton and Photon Interactions at High Energies, held in Rome, and which began yesterday.

  

  Physics Professor Wang Min-Zu, a participant in the Belle experiment, gives a presentation in front of a picture of the Extreme Forward Calorimeter.

  PHOTO: CHEN CHENG-CHANG, TAIPEI TIMES

  Most scientists are convinced that the universe was created when the Big Bang occurred about 13 billion years ago. But in the first fraction of a nanosecond, according to the Big Bang theory, that immense eruption of energy formed particles of matter and antimatter in equal proportion.

  Theory states that when matter and antimatter are created from pure energy, they appear in particle/anti-particle pairs. But when the two types of matter encounter, they annihilate one another to form energy.

  The question that scientists are trying to answer is that if the theory holds true, why does the visible universe contain so much matter, like other planets and galaxies, rather than just empty space?

  Physicists have carried out countless experiments in an attempt to answer the frequently asked question by observing the behavior of fundamental particles at high-energy states, including the experiment called Belle conducted at the High Energy Physics (KEK) accelerator laboratory in Tsukuba, Japan.

  The experiment is to measure the behavior of subatomic particles called B mesons, which are fleeting combinations of two fundamental particles named quarks.

  Taiwan got involved in the Belle experiment in Japan in 1994, when Hou Wei-shu (侯維恕), a physicist at National Taiwan University (NTU), led a team composed of physicists from the Academia Sinica, National Taiwan University, National Kaohsiung Normal University, and National Lien-Ho College of Technology and Commerce, to work with foreign scientists.

  Over the past seven years, Hou's team has received over NT$50 million in funding from the National Science Council. Taiwanese physicists produced an anti-radiation Extreme Forward Calorimeter (EFC), now installed at the KEK accelerator, to collect data pertaining to the behavior of B mesons.

  Since June 1999, the Belle experiment team has analyzed the interactions between some 31 million B meson pairs. Physicists confirm that the probability of the existence of CP violation (charge-parity violation) is larger than 99.999 percent.

  Such a violation, according to physicists, would account for a subtle inequality between the amount of matter and antimatter in the universe.

  "This is the second time in history that scientists have discovered evidence of an asymmetric phenomenon in nature," said Wang Min-zu (王名儒), a NTU physics professor and a Belle experiment team member, yesterday.

  Wang said the evidence pointing to the abundance of matter in the universe was even more convincing than that discovered in 1964, when US physicists James Cronin and Val Fitch detected the first evidence of this asymmetry in particles known as K mesons.

  Cronin and Fitch shared a Nobel Prize in 1980 for their achievements, which led to the establishment of the Standard Model, the triumph of particle physics of the 1970s.

  Today, the Standard Model is a well-established theory applicable to many branches of physics.

  Today, thirty-seven years later, followers of Cronin and Fitch have discovered secondary evidence of asymmetric phenomena in nature by observing another particle -- the B meson.

  "This new discovery ushers in a new era of physics because it might revise or verify the Standard Model," said Hwang Woei-yann (黃偉彥), chairman of the Department of Physics at NTU.
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