Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

JLab’s CLAS physicists learn a little more about ‘nothing,’ get thrown for a spin

03.07.2003


Daniel S. Carman (Ohio University) and nearly 150 members of Jefferson Lab’s CLAS Collaboration studied the spin transfer from a polarized electron beam to a produced Lambda particle. Their results were recently published in Physical Review Letters.



Measurements taken using Jefferson Lab’s CEBAF Large Acceptance Spectrometer (CLAS) are telling us more about how matter is produced from "nothing," that is, the vacuum.
Using the CLAS in Hall B, Daniel S. Carman of Ohio University and nearly 150 members of the CLAS Collaboration studied the spin transfer from a polarized electron beam to a produced Lambda particle. Their results were recently published in Physical Review Letters.

The CLAS experimenters collided JLab’s polarized electron beam into a proton target, producing a polarized Lambda (?0) and a kaon (K+). Physicists have long known that matter and anti-matter can be created when energetic particles strike one another. The new particles are not really created from "nothing." They are created from the available kinetic energy of the colliding particles. Visualize a bowling ball hitting its rack of 10 pins so hard that the 10 pins turn into 11 normal pins and one "anti-pin." Energy is conserved and so is matter; that’s why a new anti-matter particle is created each time a matter particle is created.



In a simple quark model of the reaction dynamics, a circularly polarized virtual photon strikes an oppositely polarized up quark inside the proton . The spin of the struck quark flips in direction and the quark recoils from its neighbors, stretching a flux-tube of gluonic matter between them. When the stored energy in the flux-tube is sufficient, the tube is "broken" by production of a strange quark-antiquark pair. Using this simple picture, the researchers could explain the angular dependence of the Lambda polarization if the quark pair was produced with the spins in opposite directions, or anti-aligned.

Putting the right spin on it

These anti-aligned spins could throw theorists into a spin. According to the popular triplet-P-zero (3P0) model, a quark-antiquark pair is produced with vacuum quantum numbers, and that means their spins should be aligned. These results imply that the 3P0 model may not be as widely applicable as was thought.

Winston Roberts, a theorist at Jefferson Lab and associate professor of physics at Old Dominion University, finds the CLAS measurement very interesting. "If they are right, it means we have to rethink what we thought we understood about our models for baryon decays," he says. "The CLAS results may also be saying something about what we understand of baryons themselves -- our knowledge of how to describe scattering processes such as the one they measure, or even that there may be oddities, peculiarities, dare I say ’strangeness,’ in the way strange quark-antiquark pairs are produced."

The experimenters expect further reaction from theorists. "Polarized Lambda production is obviously sensitive to the spin-dynamics of quark-pair creation," says Mac Mestayer, a JLab staff scientist, and one of the lead authors on the paper. "We eagerly await confirmation, or refutation, of the conclusions of our simple model by realistic theoretical calculations."

Meanwhile, Carman adds, the researchers are planning further experiments. "Our group is continuing this exciting research by extending our arguments to test our picture of the dynamics in different reactions."

These results show that we have much still to learn about the basic structure of the vacuum. One hundred years ago the vacuum was thought to consist of an "ether" through which light propagated as waves. Albert Michelson, Edward Morley, Albert Einstein and others disproved this hypothesis and the vacuum became an empty void. Twentieth century quantum field theories have now filled this once-empty space with virtual particles. It’s now obvious that a vacuum is not the cold, empty place it was once thought to be. JLab physicists and researchers are studying the spin of the produced quarks in hopes of understanding the vacuum better, as well as the matter that populates it.


###
by Mac Mestayer in collaboration with Melanie O’Byrne

Linda Ware | EurekAlert!
Further information:
http://www.jlab.org/

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>