53,673 research outputs found

    Search for Contact Interactions in the Dimuon Final State at ATLAS

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    The Standard Model has been successful in describing many fundamental aspects of particle physics. However, there are some remaining puzzles that are not explained within the context of its present framework. We discuss the possibility to discover new physics in the ATLAS Detector via a four-fermion contact interaction, much in the same way Fermi first described Weak interactions. Using a simple ratio method on dimuon events, we can set a 95% C.L. lower limit on the effective scale Lambda = 7.5 TeV (8.7 TeV) for the constructive Left-left Isoscalar Model of quark compositeness with 100 pb^-1 (200 pb^-1) of data at sqrt{s} = 10 TeV.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

    Comment on ``Signal of Quark Deconfinement in the Timing Structure of Pulsar Spin-Down''

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    This is a comment on a paper by Glendenning, Pei, and Weber (Phys. Rev. Lett., 79, 1603, 1997), where the authors gave an incorrect estimate of the event rate and neglected the important gravitational energy release. Previous work on the same subject is reviewed, and a new suggestion is made to link quark-hadron phase transitions with soft gamma-ray repeaters.Comment: 4 pages; to appear in Phys. Rev. Let

    Session 1-4-B: Gambling and Marijuana Use in the Netherlands: Is Legalization the Best Tool for Dealing With Naughty Habits?

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    In 1976, the Netherlands embraced two policy initiatives which encompassed similar objectives. The policies sought to control “undesired substances” via the process of legalization. One legalization process involved casino gambling. The policies have sometimes led to desired results (the right road), while at other times they have led to undesirable results (the wrong road). Now in 2013, without an observable crossroad or even fork in the road, The Netherlands is poised to deviate from a right road to travel down a wrong road by placing rather severe restrictions upon the operations of “Coffee Houses” which have been “serving” customers measured amounts of cannabis. This paper examines the experiences with the policies over the past 36 years, and speculates upon the effects of the new policies for the “Coffee Houses.” We ask if what is happening is “kinda” like an old Crystal Gayle song from the 1970s: “Down that Wrong Road Again”

    Transform-limited X-ray pulse generation from a high-brightness self-amplified spontaneous-emission free-electron laser

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    A method to achieve high-brightness self-amplified spontaneous emission (HB-SASE) in the free-electron laser (FEL) is described. The method uses repeated nonequal electron beam delays to delocalize the collective FEL interaction and break the radiation coherence length dependence on the FEL cooperation length. The method requires no external seeding or photon optics and so is applicable at any wavelength or repetition rate. It is demonstrated, using linear theory and numerical simulations, that the radiation coherence length can be increased by approximately 2 orders of magnitude over SASE with a corresponding increase in spectral brightness. Examples are shown of HB-SASE generating transform-limited FEL pulses in the soft x-ray and near transform-limited pulses in the hard x-ray. Such pulses may greatly benefit existing applications and may also open up new areas of scientific research

    High magnetic field pulsars and magnetars: a unified picture

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    We propose a unified picture of high magnetic field radio pulsars and magnetars by arguing that they are all rotating high-field neutron stars, but have different orientations of their magnetic axes with respective to their rotation axes. In strong magnetic fields where photon splitting suppresses pair creation near the surface, the high-field pulsars can have active inner accelerators while the anomalous X-ray pulsars cannot. This can account for the very different observed emission characteristics of the anomalous X-ray pulsar 1E 2259+586 and the high field radio pulsar PSR J1814-1744. A predicted consequence of this picture is that radio pulsars having surface magnetic field greater than about 2×10142\times 10^{14} G should not exist.Comment: 5 pages, emulateapj style, accepted for publication in the ApJ Letter
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