11,983 research outputs found

    Light Neutralino Dark Matter in the NMSSM

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    Neutralino dark matter is generally assumed to be relatively heavy, with a mass near the electroweak scale. This does not necessarily need to be the case, however. In the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and other supersymmetric models with an extended Higgs sector, a very light CP-odd Higgs boson can naturally arise making it possible for a very light neutralino to annihilate efficiently enough to avoid being overproduced in the early Universe. In this article, we explore the characteristics of a supersymmetric model needed to include a very light neutralino, 100 MeV < \mcnone < 20 GeV, using the NMSSM as a prototype. We discuss the most important constraints from Upsilon decays, bsγb \to s \gamma, Bsμ+μB_s \to \mu^+ \mu^- and the magnetic moment of the muon, and find that a light bino or singlino neutralino is allowed, and can be generated with the appropriate relic density. It has previously been shown that the positive detection of dark matter claimed by the DAMA collaboration can be reconciled with other direct dark matter experiments such as CDMS II if the dark matter particle is rather light, between about 6 and 9 GeV. A singlino or bino-like neutralino could easily fall within this range of masses within the NMSSM. Additionally, models with sub-GeV neutralinos may be capable of generating the 511 keV gamma-ray emission observed from the galactic bulge by the INTEGRAL/SPI experiment. We also point out measurements which can be performed immediately at CLEO, BaBar and Belle using existing data to discover or significantly constrain this scenario.Comment: References updated, accepted for publication in PR

    In-silico Predictive Mutagenicity Model Generation Using Supervised Learning Approaches

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    With the advent of High Throughput Screening techniques, it is feasible to filter possible leads from a mammoth chemical space that can act against a particular target and inhibit its action. Virtual screening complements the in-vitro assays which are costly and time consuming. This process is used to sort biologically active molecules by utilizing the structural and chemical information of the compounds and the target proteins in order to screen potential hits. Various data mining and machine learning tools utilize Molecular Descriptors through the knowledge discovery process using classifier algorithms that classify the potentially active hits for the drug development process.&#xd;&#xa

    Diboson Physics at the Tevatron

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    At the Fermilab Tevatron, the CDF and D0 detectors are being used to study diboson production in ppˉp\bar{p} collisions at s=1.96\sqrt{s}=1.96 TeV. We summarize recent measurements of the Wγ\gamma, Zγ\gamma, and WW cross-sections and limits on WZ and ZZ production. Limits on anomalous trilinear gauge couplings are also presented.Comment: 4 pages, Talk presented at the XLIrst Rencontres de Moriond - QCD and High Energy Hadronic Interactions, La Thuile, Italy, 18-25 March 200

    A Steady State Approach to a Network Externality Market With Switching Costs

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    We study duopoly pricing in the market for mobile phone service, which features network externalities, switching costs, and consumer heterogeneity. We introduce a steady state approach that enables a tractable analysis without endgame effects. The model can generate a variety of testable predictions, of which we focus on the comparative statics with respect to switching costs. Using data on the mobile phone service industries in 52 countries, we use the variation in market structure at the time switching costs were suddenly reduced by the regulatory imposition of mobile number portability (MNP). Firms that grew more rapidly prior to MNP respond to MNP by pricing more aggressively; firms facing large competitors respond less aggressively. Exploration of the model and its implications is an object of ongoing research

    Anomaly-Free Sets of Fermions

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    We present new techniques for finding anomaly-free sets of fermions. Although the anomaly cancellation conditions typically include cubic equations with integer variables that cannot be solved in general, we prove by construction that any chiral set of fermions can be embedded in a larger set of fermions which is chiral and anomaly-free. Applying these techniques to extensions of the Standard Model, we find anomaly-free models that have arbitrary quark and lepton charges under an additional U(1) gauge group.Comment: 21 (+1) page

    Parallel algorithms for generating distinguishing sequences for observable non-deterministic FSMs

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    A distinguishing sequence (DS) for a finite state machine (FSM) is an input sequence that distinguishes every pair of states of the FSM. There are techniques that generate a test sequence with guaranteed fault detection power and it has been found that shorter test sequence can be produced if DSs are used. Despite these benefits, however, until recently the only published DS generation algorithms have been for deterministic FSMs. This paper develops a massively parallel algorithm, which can be used in GPU Computing, to generate DSs from partial observable non-deterministic FSMs. We also present the results of experiments using randomly generated FSMs and some benchmark FSMs. The results are promising and indicate that the proposed algorithm can derive DSs from partial observable non-deterministic FSMs with 32,000 states in an acceptable amount of time.This work is supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant #1059B191400424 and by the NVIDIA corporation

    THE ACTIVITIES OF TURKISH ACCOUNTING STANDARDS BOARD (TASB) FOR IMPROVING THE QUALITY OF THE FINANCIAL KNOWLEDGE AND GENERAL VIEW ON TURKISH FINANCIAL REPORTING STANDARDS (TFRS)

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    Nowadays, an extremely fast developments are faced, in every field. The increase on international business activities, investment decisions, and pace of transformation in capital markets which are affected by the technological development, requires financial data to be presented in one common language. Therefore, there has been a vast increase in the effort to adopt financial accounting and reporting standarts, in all over the world. In establishing standarts for accounting and financial reporting, besides the aim for adoptation in world scale, a concern for higher quality has taken part. Setting standards increases the quality of the financial information which is the content of financial reporting. There is a worldwide tendency towards a single global set in accounting. With this objective, International Accounting Standards (IAS) and International Financial Reporting Standarts (IFRS) has been published by International Accounting Standards Board (IASB). In order to adopt to these set of standards, Turkish Accounting Standards Board (TASB) has been formed, on 18 December 1999. The Board effective from 07 March 2002, has taken the responsibility to comply with international accounting standards. With this intention, Turkish Accounting Standards (TAS) and Turkish Financial Reporting Standards (TFRS) has started to be publishe

    Breit-Wigner Enhancement of Dark Matter Annihilation

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    We point out that annihilation of dark matter in the galactic halo can be enhanced relative to that in the early universe due to a Breit-Wigner tail, if the dark matter annihilates through a pole just below the threshold. This provides a new explanation to the "boost factor" which is suggested by the recent data of the PAMELA, ATIC and PPB-BETS cosmic-ray experiments.Comment: 4 pages, 4 figure
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