Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists model the 'flicker' of gluons in subatomic smashups

03.08.2016

Model identifies fluctuations in the glue-like particles that bind quarks within protons as essential to explaining experimental data on proton structure

Scientists exploring the dynamic behavior of particles emerging from subatomic smashups at the Relativistic Heavy Ion Collider (RHIC, https://www.bnl.gov/rhic/)-a U.S. Department of Energy Office of Science User Facility for nuclear physics research at DOE's Brookhaven National Laboratory-are increasingly interested in the role of gluons. These glue-like particles ordinarily bind quarks within protons and neutrons, and appear to play an outsized role in establishing key particle properties.


These are four snapshots of the gluon density in a proton at high energy, as modeled by Mäntysaari and Schenke. Red indicates high gluon density, blue indicates low density.

Credit: Brookhaven National Laboratory

A new study just published in Physical Review Letters reveals that a high degree of gluon fluctuation-a kind of flickering rearrangement in the distribution of gluon density within individual protons-could help explain some of the remarkable results at RHIC and also in nuclear physics experiments at the Large Hadron Collider (LHC) in Europe.

Right now it's impossible to directly "see" the distribution of gluons within individual protons and nuclei-even at the most powerful particle accelerators. So Brookhaven Lab theoretical physicists Björn Schenke and Heikki Mäntysaari developed a mathematical model to represent a variety of arrangements of gluons within a proton.

... more about:
»EIC »LHC »RHIC »collisions »fluctuations »protons

"It is very accurately known how large the average gluon density is inside a proton," Mäntysaari said. "What is not known is exactly where the gluons are located inside the proton. We model the gluons as located around the three valance quarks. Then we control the amount of fluctuations represented in the model by setting how large the gluon clouds are, and how far apart they are from each other."

The fluctuations represent the behavior of gluons in particles accelerated to high energies as they are in colliders like RHIC and the LHC. Under those conditions, the gluons are virtual particles that continuously split and recombine, essentially flickering in and out of existence like fireflies blinking on and off in the nighttime sky.

Scientists would like to know if and how these fluctuations affect the behavior of the particles created when protons collide with heavy nuclei, like the gold ions accelerated at RHIC. Data from RHIC's proton-gold collisions, and from the LHC's proton-lead collisions, have shown evidence of "collective phenomena"-particles emerging with some "knowledge" of one another and in some preferred directions rather than in a uniform fashion.

In RHIC and LHC smashups of two large particles (gold-gold or lead-lead), this collective behavior and direction-dependent flow has been explained by the liquid state of quarks and gluons-the "perfect liquid" quark-gluon plasma (QGP)-created in these collisions. But collisions of tiny protons with the larger nuclei aren't supposed to create QGP. And the current understanding of the QGP can't completely explain the experimental results.

"If we want to understand what happens, we have to know the geometry of the proton just before the collisions. It makes a difference if you have a round object hitting a nucleus vs. something with a more irregular structure hitting the nucleus," Mäntysaari said. "The collective behavior we see in the experiments might imply that there is some more complex structure to the proton," he added, noting that exploring the internal structure of the proton is a fundamental research endeavor for nuclear physicists.

The model developed by Mäntysaari and Schenke describes how the proton structure can fluctuate. To test the model, they turned to a different set of experimental data-results from collisions of electrons with protons at the HERA accelerator in Germany. A particular reaction that sometimes occurs in these collisions-where a particle called a J/psi is produced and the proton breaks up into a spray of other particles-is highly dependent on the level of structural fluctuations in the proton.

The Brookhaven theorists used their model to predict the frequency of this interaction while varying the level of gluon fluctuations, and compared their calculations with the experimentally observed data. They found that the version of their model with the highest degree of fluctuations was the one that fit the data best.

"This process doesn't happen at all if the proton always looks the same. The more fluctuations we have, the more likely this process is to happen," Mäntysaari said.

He and Schenke are now looking to apply this knowledge to the proton-nucleus collisions.

"When the gluon fluctuations are incorporated into the hydrodynamic models of QGP, we get a better agreement with the experimental data from these proton-nucleus collisions," Mäntysaari said.

As Schenke noted, "This implies that the formation of a strongly interacting QGP in proton-nucleus collisions provides a possible explanation of the experimentally observed collectivity."

If the nuclear physics community gets to build a proposed future project called an Electron-Ion Collider (EIC), they'll have an opportunity to improve on the precision of these results.

"An EIC will allow us to measure this more precisely, and in different kinematics-how the fluctuations depend on energy, for example," Mäntysaari said. "And an EIC can also do the same kind of studies in nuclear targets to see how much the structure of the nucleus fluctuates event by event."

In essence, the EIC would be a true gluon-imaging machine-a way to directly probe the internal structure of the building blocks of visible matter, including the glue that binds everything in the universe today.

###

This research was funded by the DOE Office of Science.

Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.

Related Links

Scientific paper: "Evidence of Strong Proton Shape Fluctuations from Incoherent Diffraction"

APS Physics Viewpoint: Of Gluons and Fireflies

Media contacts: Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov, or Peter Genzer, (631) 344-3174, genzer@bnl.gov

Media Contact

Karen McNulty Walsh
kmcnulty@bnl.gov
631-344-8350

 @brookhavenlab

http://www.bnl.gov 

Karen McNulty Walsh | EurekAlert!

Further reports about: EIC LHC RHIC collisions fluctuations protons

More articles from Materials Sciences:

nachricht Move over, Superman! NIST method sees through concrete to detect early-stage corrosion
27.04.2017 | National Institute of Standards and Technology (NIST)

nachricht Control of molecular motion by metal-plated 3-D printed plastic pieces
27.04.2017 | Ecole Polytechnique Fédérale de Lausanne

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>