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Exploring the standard model of physics without the high-energy collider
August 11, 2009Scientists at the University of California, Berkeley, and Lawrence Berkeley National Laboratory in the US, have performed sophisticated laser measurements to detect the subtle effects of one of nature's most elusive forces - the "weak interaction". Their work, which reveals the largest effect of the weak interaction ever observed in an atom, is reported in Physical Review Letters and highlighted in the August 10th issue of APS's on-line journal Physics (physics.aps.org).
Along with gravity, electromagnetism and the strong interaction that holds protons and neutrons together in the nucleus, the weak interaction is one of the four known fundamental forces. It is the force that allows the radioactive decay of a neutron into a proton - the basis of carbon dating - to occur. However, because it acts over such a short range - about a tenth of a percent the diameter of the proton - it is almost impossible to study its effect without large, high-energy particle accelerators.
Theorists had predicted that the weak interaction between an atom's electrons and its nucleus could be quite large in Ytterbium (element 70 in the periodic table). To actually see this interaction, though, Dmitry Budker and his group at UC Berkeley had to carefully perform delicate measurements based on fundamental quantum mechanical effects and systematically eliminate other spurious signals.
The effect Budker and his colleagues see in Ytterbium is about 100 times bigger than what has been seen in Cesium, the atom in which most experiments in this field have been performed so far. The finding of such a large effect in Ytterbium poses an exciting opportunity to use tabletop atomic physics techniques as part of sensitive searches for new physics that complement ongoing efforts at the world's high-energy colliders.
American Physical Society
The effect Budker and his colleagues see in Ytterbium is about 100 times bigger than what has been seen in Cesium, the atom in which most experiments in this field have been performed so far. The finding of such a large effect in Ytterbium poses an exciting opportunity to use tabletop atomic physics techniques as part of sensitive searches for new physics that complement ongoing efforts at the world's high-energy colliders.
American Physical Society
Weak Interaction Current Events and Weak Interaction News RSSYtterbium's Broken Symmetry
Ytterbium was discovered in 1878, but until it recently became useful in atomic clocks, the soft metal rarely made the news. Now ytterbium has a new claim to scientific fame.
Argonne's Hard X-ray Nanoprobe provides new capability to study nanoscale materials
The Center for Nanoscale Materials' (CNM) newly operational Hard X-ray Nanoprobe at the U.S. Department of Energy's (DOE) Argonne National Laboratory is one of the world's most powerful x-ray microscopes.
Researchers detect low-energy neutrinos, probe energy production in sun's center
In collaboration with scientists from institutions in the United States and Europe, researchers from Virginia Tech have observed tell-tale signals of neutrinos emitted by thermonuclear fusion reactions that power the sun deep in its interior.
Single spinning nuclei in diamond offer a stable quantum computing building block
Surmounting several distinct hurdles to quantum computing, physicists at Harvard University have found that individual carbon-13 atoms in a diamond lattice can be manipulated with extraordinary precision to create stable quantum mechanical memory and a small quantum processor, also known as a quantum register, operating at room temperature.
G-Zero update
In research performed in Hall C, nuclear physicists have found that strange quarks do contribute to the structure of the proton. This result indicates that, just as previous experiments have hinted, strange quarks in the proton's quark-gluon sea contribute to a proton's properties. The result comes from work performed by the G-Zero collaboration, an international group of 108 physicists from 19 institutions, and was presented at a Jefferson Lab physics seminar on June 17.
G-Zero Finds that Ghostly Strange Quarks Influence Proton Structure
In research performed at the Department of Energy's Jefferson Lab, nuclear physicists have found that strange quarks do contribute to the structure of the proton. This result indicates that, just as previous experiments have hinted, strange quarks in the proton's quark-gluon sea contribute to a proton's properties.
The first results of Finuda will be announced on January 30th: a new window for the study of exotic atomic nuclei.
On Friday the 30th, during the XLII international winter meeting on nuclear physics at Bormio, the first results will be announced of Finuda experiment (Nuclear Physics at Daphne), settled in Frascati at Infn National Laboratories. Planned and made operating by a group of about forty physicists from Universities and Infn Sites of Bari, Brescia, Frascati, Pavia, Torino and Trieste, Finuda is devoted to the study of hypernuclei: nuclei composed by three different kinds of particles rather then two (protons and neutrons) as in ordinary nuclei. The first stage of the experiment started on October the15th and the data obtained up to now promise to be the most relevant in the study of hypernucle
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Gauge Theory of Weak Interactions by Walter Greiner (Author), Berndt Müller (Author) "Gauge Theory of Weak Interactions" treats the unification of electromagnetic and weak interactions and considers related phenomena. First, the Fermi theory of beta decay is presented, followed by a discussion of parity violation, clarifying the importance of symmetries. Then the concept of a spontaneously broken gauge theory is introduced, and all necessary mathematical tools are carefully developed. The "standard model" of unified electroweak interactions is thoroughly discussed including current developments. The final chapter contains an introduction to unified theories of strong and electroweak interactions. Numerous solved examples and problems make this volume uniquely suited as a text for an advanced course. This fourth edition has been carefully revised. |
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Weak Interactions and Modern Particle Theory (Dover Books on Physics) by Howard Georgi (Author) A high-level, rigorous, and technical treatment of modern particle physics, this book was written by a well-known professor at Harvard University. In addition to its value as a text for advanced undergraduate and graduate students of physics, it also serves as a reference for professionals. 1984 edition. |
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Gauge Theories of Weak Interactions (Cambridge Monographs on Mathematical Physics) by John C. Taylor (Author) | |
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Weak Interactions of Leptons and Quarks by Eugene D. Commins (Author), Philip H. Bucksbaum (Author) In recent years, the study of weak interaction and its relationship with the other fundamnetal interactions of nature has progressed rapidly. Weak interactions of leptons and quarks provides an up-to-date account of this continuing research. The Introduction discusses early models and historical developments in the understanding of the weak force. The authors then give a clear presentation of the modern theoretical basis of weak interactions, going on to discuss recent advances in the field. These include development of the eletroweak gauge theory, and the discovery of neutral currents and of a host of new particles. There is also a chapter devoted entirely to neutrino astrophysics. Its straightforward style and its emphasis on experimental results will make this book an excellent source... |
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Proceedings of the International School of Physics Enrico Fermi Course 23: Weak Interactions & High-Energy Neutrino Physics by T D Lee (Author) | |
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Gauge Theories of the Strong, Weak & Electromagnetic Interactions (Frontiers in Physics) by Chris Quigg (Author) This monograph presents a coherent and elementary introduction to Gauge theories of the fundamental interactions and their applications to high-energy physics. It deals with the logic and structure of local Gauge symmetries and Gauge theories, from quantum electrodynamics through unified theories of the interactions among leptons and quarks. Many explicit calculations provide the reader with practice in computing the consequences of these theories and offer a perspective on key experimental investigations. First published in 1983, this text is ideal for a one-semester course on Gauge theories and particle physics. Specialists in particle physics and others who wish to understand the basic ideas of Gauge theories will find it useful as a reference and for self-study. | |
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