Taking a smash peek deep inside the proton.
In the modern picture of the constituents of matter, the proton's composition appears straightforward: two "up" quarks Quarks
The basic constituent particles of which elementary particles are understood to be composed. Theoretical models built on the quark concept have been very successful in understanding and predicting many phenomena in the physics of elementary particles. and one "down" quark quark (kwôrk): see elementary particles.
Any of a group of subatomic particles thought to be among the fundamental constituents of matter—more specifically, of protons and neutrons. , all tied together by gluons Gluons
The hypothetical force particles believed to bind quarks into “elementary” particles. Although theoretical models in which the strong interactions of quarks are mediated by gluons have been successful in predicting, interpreting, and . But there's nothing simple about how a proton is put together--or how it falls apart. Hit a proton hard enough, and it can fragment in surprising ways.
Researchers using the Hadron hadron
Any of the subatomic particles that are built from quarks and thus interact via the strong force. The hadrons fall into two groups: mesons and baryons. Except for protons and neutrons, which are bound in nuclei, all hadrons have short lives and are produced in Electron Ring Accelerator (HERA) in Hamburg, Germany, have discovered that a proton exhibits a peculiar sort of lumpiness that apparently doesn't correspond to individual quarks or gluons. The results of high-energy collisions between electrons and protons suggest that an electron sometimes penetrates deeply enough to encounter a new kind of object buried within the proton.
"We weren't looking for Looking for
In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with. this," says Allen Caldwell of Columbia University Columbia University, mainly in New York City; founded 1754 as King's College by grant of King George II; first college in New York City, fifth oldest in the United States; one of the eight Ivy League institutions. , a member of the team running the ZEUS detector at HERA. Caldwell reported the team's findings at an American Physical Society The American Physical Society was founded in 1899 and is the world's second largest organization of physicists. The Society publishes more than a dozen science journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than twenty science meeting this week in Arlington, Va.
Researchers have long used electron beams as probes to study the structure of the proton and other subatomic particles. Typically, when an electron transfers a lot of momentum to a proton, the collisions forces the ejection of a quark. But the ejected quark can'[ exist by itself. It interacts with other quarks and antiquarks created out of the vacuum as it separates from what's left of the proton.
These quarks combine in various ways to create a jet of assorted subatomic particles that sprays out in the same direction as the ejected quark. The proton remnant also interacts with extra quarks and antiquarks to produce another jet of subatomic particles.
Researchers normally detect the deflected electron and two distinctive jets of subatomic particles. However, the ZEUS team found that nearly 10 percent of the time, only one jet appears. "This was a very surprising result, given that the proton was getting such a large kick," Caldwell says.
The most likely explanation is that the electron is deflected not by a quark, but by some other, unknown object--perhaps a particular combination of quarks and gluons--which then breaks up to form the observed jet and leaves behind a proton remnant that somehow stays intact.
"Different possibilities have been put forward," Caldwell remarks. "But the complete solution remains largely a mystery."