3,782 research outputs found

    B, Bs -> K form factors: an update of light-cone sum rule results

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    We present an improved QCD light-cone sum rule (LCSR) calculation of the B -> K and Bs -> K form factors, by including SU(3)-symmetry breaking corrections. We use recently updated K-meson distribution amplitudes which incorporate the complete SU(3)-breaking structure. By applying the method of the direct integration in the complex plane, which is presented in a detail, the analytical extraction of the imaginary parts of LCSR hard-scattering amplitudes becomes unnecessary and therefore the complexity of the calculation is greatly reduced. The values obtained for the relevant B_{(s)} -> K form factors are as follows: f^+_{BK}(0)= 0.36^{+0.05}_{-0.04}, f^+_{B_sK}(0)= 0.30^{+0.04}_{-0.03} and f^T_{BK}(0)= 0.38\pm 0.05, f^T_{B_sK}(0)= 0.30\pm 0.05. By comparing with the B -> pi form factors extracted recently by the same method, we find the following SU(3) violation among the B -> light form factors: f^+_{BK}(0)/f^+_{B\pi}(0) = 1.38^{+0.11}_{-0.10}, f^+_{B_sK}(0)/f^+_{B\pi}(0) = 1.15^{+0.17}_{-0.09}, f^T_{BK}(0)/f^T_{B\pi}(0) = 1.49^{+0.18}_{-0.06} and f^T_{B_sK}(0)/f^T_{B\pi}(0) = 1.17^{+0.15}_{-0.11}.Comment: 14 pages, 9 figures, some figures and discussions added; version to appear in PR

    Diferencijacija prednjeg krila medonosne pčele iz Srbije

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    In this study, 12 morphological characteristics were measured on worker bee samples collected from seven different locations covering the territory of Republic Serbia. The measurement of 11 angles on the front wing and cubital index was done with stereo microscope Leica XTL-3400D, and software package IL 1009 in accordance with the standard method. The results showed significant differences between the groups of bees and investigation of angles on the forewing could be contributed to a clearer separation of groups of bees inside domestic population.U ovom istraživanju mereno je 12 morfoloških karakteristika prednjeg krila pčela radilica u skladu sa metodama Ruttner i sar. (1978). Uzorci pčela radilica su prikupljeni sa 7 različitih lokacija čime su pokriveni glavni pčelarski regioni na teritoriji Republike Srbije. Morfometrijska istraživanja pokazala su da pčele iz Zapadno Bačkog regiona u Vojvodini imaju najveću vrednost uglova B4 (113,17º), D7 (100,10º), E9 (24,28º), K19 (79,60º) i najveći kubitalni indeks (2,92). Iste pčele se na osnovu multivarijantne diskriminantne analize najviše razlikuju od grupe pčela sa Kosova. Na osnovu analize varijanse, utvrđeno je da postoji vrlo značajna razlika (P lt 0.01) u 7 morfoloških karakteristika između grupa pčela sa izabranih lokaliteta. Može se zaključiti da utvrđene vrednosti za ispitivane karaktere ukazuju na postojanje značajne varijabilnosti i impliciraju na postojanje subpopulacija uslovljenih delovanjem čoveka

    Bird's-eye view on Noise-Based Logic

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    Noise-based logic is a practically deterministic logic scheme inspired by the randomness of neural spikes and uses a system of uncorrelated stochastic processes and their superposition to represent the logic state. We briefly discuss various questions such as (i) What does practical determinism mean? (ii) Is noise-based logic a Turing machine? (iii) Is there hope to beat (the dreams of) quantum computation by a classical physical noise-based processor, and what are the minimum hardware requirements for that? Finally, (iv) we address the problem of random number generators and show that the common belief that quantum number generators are superior to classical (thermal) noise-based generators is nothing but a myth.Comment: paper in pres

    Probing seesaw at LHC

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    We have recently proposed a simple SU(5) theory with an adjoint fermionic multiplet on top of the usual minimal spectrum. This leads to the hybrid scenario of both type I and type III seesaw and it predicts the existence of the fermionic SU(2) triplet between 100 GeV and 1 TeV for a conventional GUT scale of about 10^{16} GeV, with main decays into W (Z) and leptons, correlated through Dirac Yukawa couplings, and lifetimes shorter than about 10^{-12} sec. These decays are lepton number violating and they offer an exciting signature of Delta L=2 dilepton events together with 4 jets at future pp (p\bar p) colliders. Increasing the triplet mass endangers the proton stability and so the seesaw mechanism could be directly testable at LHC.Comment: 19 pages, discussion on leptogenesis added, new references, main conclusions unchange

    The impact of the transition radius lower flange-web on local stress of monorail crane girder

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    Širokopojasne profile sa paralelnom konturom pojaseva, koji se danas dominantno koriste za izradu jednošinskih nosača dizalica, karakteriše relativno veliki radijus tranzicije konture pojasa u konturu rebra. Upravo zbog toga, uticaj pomenutog radijusa na naponsko stanje izazvano lokalnim savijanjem usled dejstva točkova dizaličnih kolica znatno je izraženiji kod širokopojasnih (IPB) profila, u odnosu na klasične I profile i srednje široke (IPE) profile. U radu su prezentirani rezultati numeričko-analitičkog i eksperimentalnog istraživanja lokalnih napona u zoni tranzicije donji pojas/rebro kod širokopojasnih profila. Utvrđeno je da se najveće vrednosti razmatranih napona javljaju na početku tranzicije konture, a ne u tački fiktivnog preseka konture rebra i donje konture donjeg pojasa, kako se navodi u relevantnoj literaturi i aktuelnoj tehničkoj regulativi (standard EN 15011:2014). Osim toga, rezultati istraživanja dokazuju da apsolutne vrednosti lokalnih napona na donjoj i gornjoj konturi nisu jednake.Wide flange I-beams with parallel flange contours, which are now predominantly used in production of monorail crane girders, are characterized by a relatively large radial transition between flange contour and rib contour. Therefore, the influence of the radius on the stress state, due to the local bending caused by the action of crane trolley wheels, is more pronounced in wide-flange I-beams (IPB) than in conventional (I) and mid-wide (IPE) I-beams. This paper presents the results of numerical-analytical and experimental research of local stresses in the lower flange-rib transition zone at wide flange I-beams. It was found that the highest values of the considered stresses occur at the start of the transition contour, and not in the fictive point of intersection of the rib contour and the upper contour of the lower flange, as stated in relevant literature and current technical regulations (standard SRPS EN 15011: 2014). In addition, research results show that the absolute values of local stresses on the lower and upper contours of the lower flange are not equal

    Environmental effects of entrepreneurship indices on ecological footprint of croplands and grazing lands in the economy

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    When production resources are considered significant economic variables, the circular economy (CE) is viewed as a closed-loop economic system. It is a sustainable development strategy based on limited resources that addresses urgent problems of environmental degradation and resource scarcity and depletion. This study gives the definitions of such a strategy by thoroughly reviewing the growing research literature on the subject. Additionally, the paper reviews the rapidly growing body of literature on CE, examining its concepts and current practices and evaluating its implementation. Comparing the CE concept with the current linear economy of obtaining materials; producing, distributing, and consuming goods; and discarding waste reveals why a shift to regenerative sustainable industrial development with a closed-loop is necessary. It also compares CE with concepts like the Green Supply Chain Management in an effort to better understand their constituent dimensions. Additionally, while expressing the difficulties inherent in developing such a strategy, the paper examines the prospects and impediments to its development

    Formal description technique SDL for manufacturing systems specification and description

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    This paper addresses the formal specification and description of manufacturing systems. It is considered the use of SDL (Specification and Description Language), a standard FDT (Formal Description Technique), to model the behaviour, data and structure aspects of a manufacturing system. SDL was originally developed for telecommunication systems (protocol specification and data processing). The adequacy of FDTs, namely SDL, for the manufacturing systems domain is investigated by developing the SDL specification of part of a Distributed/Virtual Manufacturing System cell installation (D/V MS Project), and analysing it

    Radiative seesaw and degenerate neutrinos

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    The radiative see-saw mechanism of Witten generates the right-handed neutrino masses in SO(10) with the spinorial 16_H Higgs field. We study here analytically the 2nd and 3rd generations for the minimal Yukawa structure containing 10_H and 120_H Higgs representations. In the approximation of small 2nd generation masses and gauge loop domination we find the following results : (1) b-tau unification, (2) natural coexistence between large theta_l and small theta_q, (3) degenerate neutrinos.Comment: 4 page
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