1,051 research outputs found

    Expected Sensitivity to Galactic/Solar Axions and Bosonic Super-WIMPs based on the Axio-electric Effect in Liquid Xenon Dark Matter Detectors

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    We present systematic case studies to investigate the sensitivity of axion searches by liquid xenon detectors, using the axio-electric effect (analogue of the photoelectric effect) on xenon atoms. Liquid xenon is widely considered to be one of the best target media for detection of WIMPs (Weakly Interacting Massive Particles which may form the galactic dark matter) using nuclear recoils. Since these detectors also provide an extremely low radioactivity environment for electron recoils, very weakly-interacting low-mass particles (< 100 keV/c^2), such as the hypothetical axion, could be detected as well - in this case using the axio-electric effect. Future ton-scale liquid Xe detectors will be limited in sensitivity only by irreducible neutrino background (pp-chain solar neutrino and the double beta decay of 136Xe) in the mass range between 1 and 100 keV/c^2. Assuming one ton-year of exposure, galactic axions (as non-relativistic dark matter) could be detected if the axio-electric coupling g_Ae is greater than 10^-14 at 1 keV/c^2 (or $10^-13 at 100 keV/c^2). Below a few keV/c^2, and independent of the mass, a solar axion search would be sensitive to a coupling g_Ae ~ 10^-12. This limit will set a stringent upper bound on axion mass for the DFSV and KSVZ models for the mass ranges m_A < 0.1 eV/c^2 and < 10 eV/c^2, respectively. Vector-boson dark matter could also be detected for a coupling constant alpha'/alpha > 10^-33 (for mass 1 keV/c^2) or > 10^-27 (for mass 100 keV/c^2).Comment: 17 pages, 10 figure

    K_L \ra \mu^\pm e^\mp \nu \overline{\nu} as background to K_L \ra \mu^\pm e^\mp

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    We consider the process K_L \ra \mu^\pm e^\mp \nu \overline{\nu} at next to leading order in chiral perturbation theory. This process occurs in the standard model at second order in the weak interaction and constitutes a potential background in searches for new physics through the modes K_L \ra \mu^\pm e^\mp. We find that the same cut, Mμe>489M_{\mu e}>489~MeV, used to remove the sequential decays K_{l3}\ra \pi_{l2} pushes the B(K_L \ra \mu^\pm e^\mp \nu \overline{\nu}) to the 102310^{-23} level, effectively removing it as a background.Comment: 8 pages, LaTeX, 1 figure appended as postscript file after \end{document}. Fermilab-Pub-93/024-

    Developments in Rare Kaon Decay Physics

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    We review the current status of the field of rare kaon decays. The study of rare kaon decays has played a key role in the development of the standard model, and the field continues to have significant impact. The two areas of greatest import are the search for physics beyond the standard model and the determination of fundamental standard-model parameters. Due to the exquisite sensitivity of rare kaon decay experiments, searches for new physics can probe very high mass scales. Studies of the k->pnn modes in particular, where the first event has recently been seen, will permit tests of the standard-model picture of quark mixing and CP violation.Comment: One major revision to the text is the branching ratio of KL->ppg, based on a new result from KTeV. Several references were updated, with minor modifications to the text. A total of 48 pages, with 28 figures, in LaTeX; to be published in the Annual Review of Nuclear and Particle Science, Vol. 50, December 200

    Analytic calculations of the spectra of ultra high energy cosmic ray nuclei. II. The general case of background radiation

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    We discuss the problem of ultra high energy nuclei propagation in extragalactic background radiations. The present paper is the continuation of the accompanying paper I where we have presented three new analytic methods to calculate the fluxes and spectra of ultra high energy cosmic ray nuclei, both primary and secondary, and secondary protons. The computation scheme in this paper is based on the analytic solution of coupled kinetic equations, which takes into account the continuous energy losses due to the expansion of the universe and pair-production, together with photo-disintegration of nuclei. This method includes in the most natural way the production of secondary nuclei in the process of photo-disintegration of the primary nuclei during their propagation through extragalactic background radiations. In paper I, in order to present the suggested analytical schemes of calculations, we have considered only the case of the cosmic microwave background radiation, in the present paper we generalize this computation to all relevant background radiations, including infra-red and visible/ultra-violet radiations, collectively referred to as extragalactic background light. The analytic solutions allow transparent physical interpretation of the obtained spectra. Extragalactic background light plays an important role at intermediate energies of ultra high energy cosmic ray nuclei. The most noticeable effect of the extragalactic background light is the low-energy tail in the spectrum of secondary nuclei.Comment: The paper is the second part of a two papers series, it is composed by 25 pages and 16 eps figures, version accepted for publication on Astroparticle Physic

    Abstract Argumentation / Persuasion / Dynamics

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    The act of persuasion, a key component in rhetoric argumentation, may be viewed as a dynamics modifier. We extend Dung's frameworks with acts of persuasion among agents, and consider interactions among attack, persuasion and defence that have been largely unheeded so far. We characterise basic notions of admissibilities in this framework, and show a way of enriching them through, effectively, CTL (computation tree logic) encoding, which also permits importation of the theoretical results known to the logic into our argumentation frameworks. Our aim is to complement the growing interest in coordination of static and dynamic argumentation.Comment: Arisaka R., Satoh K. (2018) Abstract Argumentation / Persuasion / Dynamics. In: Miller T., Oren N., Sakurai Y., Noda I., Savarimuthu B., Cao Son T. (eds) PRIMA 2018: Principles and Practice of Multi-Agent Systems. PRIMA 2018. Lecture Notes in Computer Science, vol 11224. Springer, Cha

    Lepton Flavor Violation in the Two Higgs Doublet Model type III

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    We consider the Two Higgs Doublet Model (2HDM) of type III which leads to Flavour Changing Neutral Currents (FCNC) at tree level in the leptonic sector. In the framework of this model we can have, in principle, two situations: the case (a) when both doublets acquire a vacuum expectation value different from zero and the case (b) when only one of them is not zero. In addition, we show that we can make two types of rotations for the flavor mixing matrices which generates four types of lagrangians, with the rotation of type I we recover the case (b) from the case (a) in the limit tanβ\tan \beta \to \infty , and with the rotation of type II we obtain the case (b) from (a) in the limit tanβ0.\tan \beta \to 0. Moreover, two of the four possible lagrangians correspond to the models of types I and II plus Flavor Changing (FC) interactions. The analitical expressions of the partial lepton number violating widths Γ(μeee)\Gamma (\mu \to eee) and Γ(μeγ)\Gamma (\mu \to e\gamma) are derived for the cases (a) and (b) and both types of rotations. In all cases these widths go asymptotically to zero in the decoupling limit for all Higgses. We present from our analysis upper bounds for the flavour changing transition μe,\mu \to e, and we show that such bounds are sensitive to the VEV structure and the type of rotation utilized.Comment: 7 pages RevTeX4, 4 figures postscript, new section added and some new reference

    Monte-Carlo Simulation for an Aerogel Cherenkov Counter

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    We have developed a Monte-Carlo simulation code for an aerogel \v Cerenkov Counter which is operated under a strong magnetic field such as 1.5T. This code consists of two parts: photon transportation inside aerogel tiles, and one-dimensional amplification in a fine-mesh photomultiplier tube. It simulates the output photoelectron yields as accurately as 5% with only a single free parameter. This code is applied to simulations for a B-Factory particle-identification system.Comment: 40 pages, latex(article), 19 figure

    Rare Kaon Decays

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    The current status of rare kaon decay experiments is reviewed. New limits in the search for Lepton Flavor Violation are discussed, as are new measurements of the CKM matrix.Comment: 8 pages, 3 figures, LaTeX, presented at the 3rd International Conference on B Phyiscs and CP Violation, Taipei December 3-7, 199

    Beam test results for the FiberGLAST instrument

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    The FiberGLAST scintillating fiber telescope is a large-area instrument concept for NASA\u27s GLAST program. The detector is designed for high-energy gamma-ray astronomy, and uses plastic scintillating fibers to combine a photon pair tracking telescope and a calorimeter into a single instrument. A small prototype detector has been tested with high energy photons at the Thomas Jefferson National Accelerator Facility. We report on the result of this beam test, including scintillating fiber performance, photon track reconstruction, angular resolution, and detector efficiency

    Search for Light Gluinos via the Spontaneous Appearance of pi+pi- Pairs with an 800 GeV/c Proton Beam at Fermilab

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    We searched for the appearance of pi+pi- pairs with invariant mass greater than 648 MeV in a neutral beam. Such an observation could signify the decay of a long-lived light neutral particle. We find no evidence for this decay. Our null result severely constrains the existence of an R0 hadron, which is the lightest bound state of a gluon and a light gluino, and thereby also the possibility of a light gluino. Depending on the photino mass, we exclude the R0 in the mass and lifetime ranges of 1.2 -- 4.6 GeV and 2E-10 -- 7E-4 seconds, respectively. (To Appear in Phys. Rev. Lett.)Comment: Documentstyle aps,epsfig,prl (revtex), 6 pages, 7 figure
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