- Published on 10 August 2012
An interesting feature of black holes is the existence of quasi-normal modes, arising because the system has a peak in the wave potential (scalar, electromagnetic, or gravitational waves). The quasi-normal mode is excited when a disturbance is put in the field near but outside the black hole, (like a wave packet roughly in a circular orbit near the peak). The excitation then propagates outward and inward and decays.
- Published on 26 August 2011
The twin paradox has been a source of debate since it was discovered by Einstein. It can be analytically verified assuming the existence of global nonrotating inertial frames.The natural nonrotating frame and its identification with "fixed stars" is an aspect of Mach's Principle, which holds that the totality of matter in the universe determines the inertial frames.
- Published on 24 August 2011
At present there are no known elementary scalar fields. A possible candidate is the as yet undiscovered Higgs particle; however it could well be that this elusive particle is instead composite. This possibility is exhaustively examined in this article, which is both tutorial and extensive review, classifying the diverse technicolor models as extensions of the Standard Model of particle physics.
- Published on 17 August 2011
To date the most successful efforts to solve the irregular boundary Helmholtz equation with Neumann boundary conditions have been computational, but even this general method has its drawbacks. Panda et al. provide a new analytic approach which solves the irregular boundary problem via a perturbative series. As the authors show by working out several nontrivial examples, the benefits of this approach include a precise understanding of the behavior of the solution as the amplitude of the boundary distortion is increased, as well as the control over the analytic precision in the terms computed and its corresponding analytic error estimates. more
- Published on 10 August 2011
Oncological hadron therapy was first proposed 65 years ago by Robert R. Wilson, and it took more than 40 years to build the first dedicated facility, in Loma Linda in the nineties. The growth of new facilities since then has been exponential, and thousands of patients are now treated every year. Close collaboration between research institutes, clinical centers and industry is the basis and the future of this field. This EPJ Plus focus issue spotlights the status of hadron therapy in Europe, where different centers are already in operation, some are just now ready to start patient treatments, and new ones are being planned. more
- Published on 10 June 2011
While the hunt is on for the Higgs at the LHC, model building continues to explore also other scenarios. Here, an ultraviolet complete electroweak model is presented that assumes running coupling constants described by energy-dependent entire functions. Contrary to the conventional formulation the action contains no physical scalar fields and no Higgs particle, even if the foreseen masses for particles are compatible with known experimental values.
- Published on 17 February 2011
The need to store, distribute and analyze the 15 million gigabytes of data annually generated by the Large Hadron Collider (LHC) at CERN has led to a revolutionary development of innovative software tools. Under CERN coordination, leading IT teams have tested and validated cutting-edge software technologies aimed to operate distributed computing and data storage infrastructures based on a worldwide network of hundreds of computing centers on an unprecedented scale.