The Purpose of BABAR

Stanford Physics Professor Pat Burchat and student Ho Jeong Kim in the BaBar main control room.

BABAR is a multi-year particle physics experiment designed to study some of the most fundamental questions about the universe by exploring its smallest and most basic constituents – elementary particles. Originally, the main question motivating the construction of BABAR was

What are the differences between matter and antimatter and do these differences explain why the universe contains matter and essentially no antimatter?

However, BABAR proved to be extremely successful in exploring additional important topics related to our basic understanding of the universe, such as

Are there fundamental particles beyond those already discovered?
How can we improve our understanding of the properties of particles and the way they interact?
Do fundamental particles bind together in new ways we don’t know about?
What do we learn from patterns of radioactive decays of elementary particles?
What are the precise parameters that describe the particle world?
Which theoretical ideas about the universe are viable and which are in disagreement with experiment?
Do dark-matter particles interact with normal particles in ways other than gravity?

What has BABAR Discovered?

These questions are the subject of intensive, ongoing research. Nonetheless, BABAR has already been very successful in shedding light on all of them, furthering the understanding of the universe and providing guidance for other current and future particle-physics experiments.

Here is a quick overview of some of BABAR's achievements and ongoing research:

BABAR's precise measurements of differences between matter and antimatter have proved the theory of Makoto Kobayashi and Toshihide Maskawa, resulting in the awarding of the 2008 Nobel Prize in Physics. Ongoing research in this area focuses on new sources of asymmetry, beyond the currently known theory.
BABAR has discovered and continues to study new particles (“charmonium-like” states) that are composed of a charm quark and an anti-charm quark bound together by the strong nuclear interaction. However, some of their properties suggest that they are more complicated, perhaps containing additional quarks or reflecting unknown aspects the strong interaction.
BABAR performs stringent tests of new theories by precisely measuring various properties of particles and of their radioactive decays, in particular those of the bottom and charm quarks and of the tau lepton.
Lastly, BABAR tests new ideas that predict the existence of new particles of various types, such as low-mass Higgs, dark gauge bosons, and pentaquarks.

Learn More

See the Physics page for more details.
Visit the Publications page to see the scientific results of BABAR's studies so far.
The News page includes non-specialist explanations for a selection of BABAR results.