Tag Archives: quarks

A Closer Look at the Perfect Fluid

Researchers at Berkeley Lab and their collaborators have honed a way to probe the quark-gluon plasma, the kind of matter that dominated the universe immediately after the big bang.

By combining data from two high-energy accelerators, nuclear scientists have refined the measurement of a remarkable property of exotic matter known as quark-gluon plasma. The findings reveal new aspects of the ultra-hot, “perfect fluid” that give clues to the state of the young universe just microseconds after the big bang. (more…)

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Was das Proton umtreibt

Teilchenphysiker der Universität Tübingen weisen erstmals den Gluonen eine wichtige Rolle beim Drehimpuls der Atombausteine zu

Protonen und Neutronen sind Bausteine aller Atomkerne und damit aller Materie. Sie setzen sich ihrerseits aus kleineren Teilchen zusammen, jeweils drei Quarks, die keine eigene innere Struktur aufweisen und durch sogenannte Gluonen aneinander gebunden werden. Das Proton besitzt außerdem einen Drehimpuls („Spin“), von dem Physiker lange annahmen, dass er in erster Linie von den Quarks verursacht wird. 1987 jedoch ergab ein Experiment an der Großforschungseinrichtung CERN, dass der Spin des Protons nur zu einem kleinen Teil durch die Spins der Quarks entsteht ‒ und die Teilchenphysik stürzte in die „Spin-Krise“. Nun haben Wissenschaftler der Universität Tübingen erstmals festgestellt, dass den Gluonen eine wichtige Rolle zukommt und sie möglicherweise den Hauptanteil des Spins tragen.   (more…)

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Exotisches Teilchen bestätigt

Tübinger Forscher: Bei Experimenten mit dem COSY-Beschleuniger Quarks im Sechserpack nachgewiesen

Über Jahrzehnte haben Physiker vergeblich nach exotischen Bindungszuständen gefahndet, die aus mehr als drei Quarks bestehen. Wissenschaftler der Universität Tübingen waren an einem Experiment am Jülicher Beschleuniger COSY beteiligt, das nun zeigt: In der Natur kommen tatsächlich derartige komplexe Teilchen vor. Ihre Erkenntnisse hat die WASA-at-COSY Kollaboration in der Fachzeitschrift „Physical Review Letters“ veröffentlicht.   (more…)

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Heavy Flavor Tracker for STAR

New Detector System from Berkeley Lab for Quark-Gluon Plasma Studies May Lead to Better Understanding of Early Universe

In the first few microseconds after the big bang, the universe was a superhot, superdense primordial soup of “quarks” and “gluons,” particles of matter and carriers of force respectively. This quark-gluon plasma cooled almost instantly but it’s brief existence set the stage for the universe we know today. To better understand how our universe evolved, scientists are re-creating a quark-gluon plasma in giant particle accelerators such as the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL), where an elaborate experiment called “STAR,” for Solenoidal Tracker at RHIC, has been collecting and analyzing data for the past decade. The STAR experiment is now poised for a major upgrade with the introduction of a new particle detector system, called the “Heavy Flavor Tracker,” that is the most advanced of its kind in the world. (more…)

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Foundations of Carbon-Based Life Leave Little Room for Error

Life as we know it is based upon the elements of carbon and oxygen. Now a team of physicists, including one from North Carolina State University, is looking at the conditions necessary to the formation of those two elements in the universe. They’ve found that when it comes to supporting life, the universe leaves very little margin for error.

Both carbon and oxygen are produced when helium burns inside of giant red stars. Carbon-12, an essential element we’re all made of, can only form when three alpha particles, or helium-4 nuclei, combine in a very specific way.  The key to formation is an excited state of carbon-12 known as the Hoyle state, and it has a very specific energy – measured at 379 keV (or 379,000 electron volts) above the energy of three alpha particles. Oxygen is produced by the combination of another alpha particle and carbon. (more…)

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Do We Live in a Computer Simulation? UW Researchers Say Idea Can be Tested

A decade ago, a British philosopher put forth the notion that the universe we live in might in fact be a computer simulation run by our descendants. While that seems far-fetched, perhaps even incomprehensible, a team of physicists at the University of Washington has come up with a potential test to see if the idea holds water.

The concept that current humanity could possibly be living in a computer simulation comes from a 2003 paper published in Philosophical Quarterly by Nick Bostrom, a philosophy professor at the University of Oxford. In the paper, he argued that at least one of three possibilities is true:

  • The human species is likely to go extinct before reaching a “posthuman” stage.
  • Any posthuman civilization is very unlikely to run a significant number of simulations of its evolutionary history.
  • We are almost certainly living in a computer simulation. (more…)

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What’s Happening with the Higgs Boson

Berkeley Lab scientists, major contributors to the ATLAS experiment at the Large Hadron Collider, explain what the excitement is about

CERN, the European Organization for Nuclear Research headquartered in Geneva, Switzerland, will hold a seminar early in the morning on July 4 to announce the latest results from ATLAS and CMS, two major experiments at the Large Hadron Collider (LHC) that are searching for the Higgs boson. Both experimental teams are working down to the wire to finish analyzing their data, and to determine exactly what can be said about what they’ve found.

“We do not yet know what will be shown on July 4th,” says Ian Hinchliffe, a theoretical physicist in the Physics Division at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), who heads the Lab’s participation in the ATLAS experiment. “I have seen many conjectures on the blogs about what will be shown: these are idle speculation. Things are moving very fast this week, and it’s an exciting time at CERN. Many years of hard work are coming to fruition.” (more…)

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