1,010 research outputs found
Predictions with Lattice QCD
In recent years, we used lattice QCD to calculate some quantities that were
unknown or poorly known. They are the dependence of the form factor in
semileptonic decay, the leptonic decay constants of the and
mesons, and the mass of the meson. In this paper, we summarize
these calculations, with emphasis on their (subsequent) confirmation by
measurements in , and collisions.Comment: 5 pages; update of hep-lat/0509169, with experimental confirmation of
form factors from Belle and fDs from BaBar; presented at SciDAC 2006 for the
Fermilab Lattice, MILC, and HPQCD Collaboration
Automated Correctness Proof of Algorithm Variants in Elliptic Curve Cryptography
The Elliptic Curve Cryptography (ECC) is widely known as secure and reliable
cryptographic scheme. In many situations the original cryptographic algorithm is
modified to improve its efficiency in terms like power consumption or memory
consumption which were not in the focus of the original algorithm. For all this
modification it is crucial that the functionality and correctness of the original
algorithm is preserved. In particular, various projective coordinate systems are
applied in order to reduce the computational complexity of elliptic curve encryption
by avoiding division in finite fields. This work investigates the possibilities of
automated proofs on the correctness of different algorithmic variants. We introduce
the theorems which are required to prove the correctness of a modified algorithm
variant and the lemmas and definitions which are necessary to prove these goals.
The correctness proof of the projective coordinate system transformation has practically
been performed with the help of the an interactive formal verification system
XeriFun
The Technology of The Manufacturing Thin Wire of TiNi-based Alloys by Using Infrared Radiation
The paper describes the technology of manufacturing a thin nickel-titanium wire through direct exposure to infrared radiation (IR). The effect of IR on the change in the structure of a thin wire made from the TiNi-based alloy was studied during its manufacturing. A comparative analysis of the Ti, Ni and O concentration in the TiNi wire was carried out. The analysis was performed for both a thin wire exposed to infrared radiation and that not exposed to infrared radiation. The wire samples were studied using a scanning electron microscope with the energy dispersive analysis. The infrared radiation effect on the structure of the wire is shown after thermal treatment in the local area of the material
R Parity violating enhancement of Bu -> l nu and Bc -> l nu
We study the decays Bu -> l nu and Bc -> l nu in the context of the Minimal
Supersymmetric Standard Model (MSSM) with explicit R parity violation. We
analyse the correlation between the two decays and show that branching ratios
(BRs) for Bc -> l nu may be of order 5% (over 40% in one case), without
violating current bounds on Bu -> l nu. Although Bc mesons are inaccessible at
the e+e- B factories, such large BRs for Bc -> l nu would possibly be within
experimental observability at LEP and the Tevatron Run II, with much larger
yields expected at the hadronic B factories. We also update some earlier bounds
on products of R parity violating couplings in the light of new experimental
results.Comment: Notation in the introduction clarified, version to be published in
PLB. (12 pages, 2 figures
Remark on the Theoretical Uncertainty in - Mixing
We re-examine the theoretical uncertainty in the Standard Model expression
for - mixing. We focus on lattice calculations of the ratio
, needed to relate the oscillation frequency of -
mixing to . We replace the usual linear chiral extrapolation with one
that includes the logarithm that appears in chiral perturbation theory. We find
a significant shift in the ratio , from the conventional to
.Comment: Lattice2002(heavyquark), 3 pages, 3 figure
Высокочастотный конденсатор с рабочим веществом «изолятор нелегированный кремний изолятор»
The study of the parameters of capacitors with various working substances is of interest for the design and creation of electronic elements, in particular for the development of high-frequency phase-shifting circuits.The purpose of the work is to calculate the high-frequency capacitance of a capacitor with the working substance "insulator-undoped silicon-insulator" at different applied to the capacitor direct current (DC) voltages, measuring signal frequencies and temperatures.A model of such the capacitor is proposed, in which 30 µm thick layer of undoped (intrinsic) crystalline silicon (i-Si) is separated from each of the capacitor electrodes by 1 µm thick insulator layer (silicon dioxide).The dependences of the capacitor capacitance on the DC electrical voltage U on metal electrodes at zero frequency and at the measuring signal frequency of 1 MHz at absolute temperatures T = 300 and 400 K are calculated. It is shown that the real part of the capacitor capacitance increases monotonically, while the imaginary part is negative and non-monotonically depends on U at the temperature T = 300 K. An increase in the real part of the capacitor capacitance up to the geometric capacitance of oxide layers with increasing temperature is due to a decrease in the electrical resistance of i-Si layer. As a result, with an increase in temperature up to 400 K, the real and imaginary parts of the capacitance take constant values independent of U. The capacitance of i-Si layer with an increase in both temperature T and voltage U is shunted by the electrical conductivity of this layer. The phase shift is determined for a sinusoidal electrical signal with a frequency of 0.3, 1, 10, 30, 100, and 300 MHz applied to the capacitor at temperatures 300 and 400 K.Исследование параметров электрических конденсаторов с различными рабочими веществами представляет интерес для проектирования и создания элементов электроники, в частности для разработки высокочастотных фазосдвигающих цепей.Цель работы рассчитать высокочастотную электрическую емкость конденсатора с рабочим веществом «изолятор нелегированный кремний изолятор» при различных подаваемых на конденсатор постоянных напряжениях, частотах измерительного сигнала и температурах.Предложена модель такого конденсатора, в которой слой нелегированного (собственного) кристаллического кремния (i-Si) толщиной 30 мкм отделен от каждого из электродов конденсатора слоем изолятора (диоксида кремния) толщиной 1 мкм.Рассчитаны зависимости емкости конденсатора от постоянного электрического напряжения U на металлических электродах на нулевой частоте и на частоте измерительного сигнала 1 МГц при абсолютных температурах T = 300 и 400 К. Показано, что действительная часть емкости конденсатора монотонно возрастает, а мнимая часть отрицательна и немонотонно зависит от U при температуре T = 300 К. Увеличение действительной части емкости конденсатора до геометрической емкости оксидных слоев при увеличении температуры обусловлено уменьшением электрического сопротивления слоя i-Si. Вследствие этого с увеличением температуры до 400 К действительная и мнимая части емкости принимают постоянные значения, независящие от U. Емкость слоя i-Si при увеличении как температуры T, так и напряжения U шунтируется электрической проводимостью этого слоя. Определен сдвиг фаз для синусоидального электрического сигнала с частотой 0,3; 1; 10; 30; 100 и 300 МГц, подаваемого на конденсатор при температурах 300 и 400 К
Chiral corrections and lattice QCD results for fBs/fBd and (Delta ms/Delta md)
It has been argued recently that the inclusion of the chiral logarithms in
extrapolation of the lattice data can shift the value of the hadronic parameter
xi = (fBs sqrt(B_{Bs}))/(fBd sqrt(B_{Bd})), from 1.16(6) to 1.32(10) and even
higher. If true, that would considerably change the theoretical estimate for
the ratio of oscillation frequencies in the neutral Bs- and Bd-systems, and
would affect the standard CKM unitarity triangle analysis. In this letter we
show that (fBs/fBd) \approx (fK/fpi), and thus the uncertainty due to the
missing chiral logs is smaller than previously thought. By combining the NLO
chiral expansion with the static heavy quark limit we obtain xi = 1.22(8).Comment: Published versio
Probing Yukawa Unification with K and B Mixing
We consider corrections to the unification of down-quark and charged-lepton
Yukawa couplings in supersymmetric GUTs, which links the large nu_tau-nu_mu
mixing angle to b -> s transitions. These corrections generically occur in
simple grand-unified models with small Higgs representations and affect s -> d
and b -> d transitions via the mixing of the corresponding right-handed
superpartners. On the basis of a specific SUSY-SO(10) model, we analyze the
constraints from K-Kbar and B-Bbar mixing on the additional
\tilde{d}_R-\tilde{s}_R rotation angle theta. We find that epsilon_K already
sets a stringent bound on theta, theta^{max}=O(1 degree), indicating a very
specific flavor structure of the correction operators. The impact of the large
neutrino mixings on the unitarity triangle analysis is also briefly discussed,
as well as their ability to account for the sizeable CP-violating phase
observed recently in B_s -> psi phi decays.Comment: 19 pages. Discussion in Sec. 5.2 slightly extended; minor numerical
modifications in Secs. 5.1 to 5.4, conclusions unchanged. Version to appear
in JHE
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