The ‘Impossible’ Particle Adds a Piece to the Force Puzzle Force

This spring, at a quark physics group meeting at Syracuse University, Ivan Polyakov announces that he knows the fingerprints of a semi-mythological fragment.

“We said,‘ It’s impossible. What mistake did you make? ‘”I remember Sheldon’s stone, the group leader.

Polyakov went and reviewed his analysis of data from the Syracuse group’s Multiple Hadron Collider (LHCb) experiment. The evidence held. This shows that a specific set of four basic particles called a quark can form a tight set, contrary to what most theorists believe. The LHCb collaboration reported the discovery of the particle fragment, called the double-beauty tetraquark, at a conference in July and in two papers posted earlier this month which is now undergoing age review.

The unexpected discovery of the double beauty tetraquark highlights an uncomfortable fact. While physicists know the exact equation that defines the dynamic force-the principal force that binds quarks to form protons and neutrons in the hearts of atoms, as well as other particle particles. fragments like tetraquarks – they rarely solve this strange, infinite iterative equation, so they struggle to predict the effects of strong force.

The tetraquark now presents theorists with a solid target counter with which to test their mathematical machinery for estimating force. Asking for their estimates represents physicists ’primary hope for understanding how quarks behave inside and outside atoms – and for judging the effects of quarks from subtle signs in bags. -the basic particle pursued by physicists.

Quark Cartoon

The strange thing about quarks is that physicists can approach them with two levels of complexity. In the 1960s, struggling with a zoo of newly discovered elements in combination, they created the cartoonish “quark model,” which simply states that the quark glom combines into complementary sets of three to form the proton, neutrons, and other baryons, while pairs of The quark consist of different types of meson particles.

Gradually, a more in -depth theory known as quantum chromodynamics (QCD) emerged. This paints the proton as a seething mass in the quark combined with digging cords of “gluon” particles, the carriers of strong forces. Experiments have confirmed many aspects of QCD, but no known mathematical methods can be made systematically. remove the central equation of the theory.

However, the quark model can stand for a more complex fact, at least in part with the menagerie of baryons and mesons discovered in the 20th century. But the model failed to anticipate the transient tetraquark and five-quark “pentaquark” that began to appear in the 2000s. These exotic particles certainly came from QCD, but for almost 20 years, theorists have figured out how.

“We don’t know the pattern yet, which is embarrassing,” he said Eric Braaten, a particle theory at Ohio State University.

The latest tetraquark sharpens the mystery.

It shows more than 200 collisions in the LHCb experiment, in which protons break into each other 40 million times per second, giving quarks countless times to cross in all the ways allowed. in nature. The quark has six “flavors” of mass, with the heavier quark being more rarely seen. Each of the 200 consecutive collisions generates enough energy to produce two quarks with a tasteful beauty, with a weight more than the lighter quark containing protons but shorter than the large “beauties”. quark which is the main quarry of LHCb. The middleweight beauty quark also gets enough appeal to each and strings the two lightweight antiquarks. Polyakov’s analysis suggested that the four quarks converge for a glorious 12 sextillionths of a second before a rapid transformation into two additional quarks and the group disintegrates into three mesons.

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