Impact of Subleading Corrections on Hadronic B Decays

We study the subleading corrections originating from the 3-parton (q\bar q g) Fock states of final-state mesons in B decays. The corrections could give significant contributions to decays involving an \omega or \eta^{(\prime)} in the final states. Our results indicate the similarity of \omega K and \omega \pi^- rates, of order 5\times 10^{-6}, consistent with the recent measurements. We obtain a_2(B\to J/\psi K)\approx 0.27+0.05i, in good agreement with data. Without resorting to the unknown singlet annihilation effects, 3-parton Fock state contributions can enhance the branching ratios of K\eta' to the level above 50\times 10^{-6}.Comment: 5 pages, 5 figures, revtex4; some typos corrected, a new figure and a reference added, more explanations for the calculation provided, to appear in Phys. Rev.

Mechanical properties, wear and corrosion of boronized N80 tube steel

The effect of boronizing on mechanical properties, wear and corrosion of boronized N80 tube steel is studied. A dual-phase boride layer consisting of FeB and F₂B phases was formed on the surface of steel substrate in a hardness range of 1220 to1340 HV. A set-up to use less boriding agent and accelerate the pipe’s cooling process was designed. In order to meet the tensile properties of N80 steel required by API SPEC 5L, four cooling methods were employed. The fan-cooling with a graphite bar inside the boriding agent resulted in the highest mechanical properties, in accordance with the mechanical properties of API SPEC 5L. The boronized N80 steel showed a high wear resistance under dry sliding condition and excellent corrosion resistance in as-received oilfield water from Jilin oil field, Northeast China.Изучено влияние борирования на механические свойства, изнашивание и коррозию трубной стали N80. На поверхности стальной подкладки сформирован двухфазный боридный слой на основе FeB и F₂B с твердостью 1220...1340 HV. Разработаны способы для уменьшения количества компонента для борирования и ускорения охлаждения. Для обеспечения высоких механических характеристик при растяжении согласно спецификации API SPEC 5L использованы четыре метода охлаждения. Вентиляторное охлаждение с графитовым бруском внутри борированного реагента обусловило наиболее высокие механические характеристики. Борированная сталь выявила высокие износостойкость в условиях сухого трения и коррозийную прочность в воде нефтяного промысла в Китае в провинции Джулин.Вивчено вплив борування на механічні властивості, зношування та корозію трубної сталі N80. На поверхні сталевої підкладки сформовано двофазний боридний шар на основі FeB і F₂B з твердістю 1220...1340 HV. Розроблено способи для зменшення кількості компонента для борування та пришвидшення охолодження. Для забезпечення високих механічних характеристик за розтягу згідно зі специфікацією API SPEC 5L використано чотири методи охолодження. Вентиляторне охолодження з графітовим бруском всередині борувального реагента призвело до найвищих механічних характеристик. Борована сталь виявила високі зносотривкість за сухого тертя та корозійну міцність у воді з нафтового родовища в Китаї у провінції Джулін

Causal explanation for observed superluminal behavior of microwave propagation in free space

In this paper we present a theoretical analysis of an experiment by Mugnai and collaborators where superluminal behavior was observed in the propagation of microwaves. We suggest that what was observed can be well approximated by the motion of a superluminal X wave. Furthermore the experimental results are also explained by the so called scissor effect which occurs with the convergence of pairs of signals coming from opposite points of an annular region of the mirror and forming an interference peak on the intersection axis traveling at superluminal speed. We clarify some misunderstandings concerning this kind of electromagnetic wave propagation in vacuum.Comment: 9 pages, 3 figures, accepted for publication in Physics Letters

Deformation independent open brane metrics and generalized theta parameters

We investigate the consequences of generalizing certain well established properties of the open string metric to the conjectured open membrane and open Dp-brane metrics. By imposing deformation independence on these metrics their functional dependence on the background fields can be determined including the notorious conformal factor. In analogy with the non-commutativity parameter $\Theta^{\mu\nu}$ in the string case, we also obtain `generalized' theta parameters which are rank q+1 antisymmetric tensors (polyvectors) for open Dq-branes and rank 3 for the open membrane case. The expressions we obtain for the open membrane quantities are expected to be valid for general background field configurations, while the open D-brane quantities are only valid for one parameter deformations. By reducing the open membrane data to five dimensions, we show that they, modulo a subtlety with implications for the relation between OM-theory and NCYM, correctly generate the open string and open D2-data.Comment: 24 pages, LaTe

On low temperature kinetic theory; spin diffusion, Bose Einstein condensates, anyons

The paper considers some typical problems for kinetic models evolving through pair-collisions at temperatures not far from absolute zero, which illustrate specific quantum behaviours. Based on these examples, a number of differences between quantum and classical Boltzmann theory is then discussed in more general terms.Comment: 25 pages, minor updates of previous versio

Incipient Separation in Shock Wave Boundary Layer Interactions as Induced by Sharp Fin

The incipient separation induced by the shock wave turbulent boundary layer interaction at the sharp fin is the subject of present study. Existing theories for the prediction of incipient separation, such as those put forward by McCabe (1966) and Dou and Deng (1992), can have thus far only predicting the direction of surface streamline and tend to over-predict the incipient separation condition based on the Stanbrook's criterion. In this paper, the incipient separation is firstly predicted with Dou and Deng (1992)'s theory and then compared with Lu and Settles (1990)' experimental data. The physical mechanism of the incipient separation as induced by the shock wave/turbulent boundary layer interactions at sharp fin is explained via the surface flow pattern analysis. Furthermore, the reason for the observed discrepancy between the predicted and experimental incipient separation conditions is clarified. It is found that when the wall limiting streamlines behind the shock wave becomes\ aligning with one ray from the virtual origin as the strength of shock wave increases, the incipient separation line is formed at which the wall limiting streamline becomes perpendicular to the local pressure gradient. The formation of this incipient separation line is the beginning of the separation process. The effects of Reynolds number and the Mach number on incipient separation are also discussed. Finally, a correlation for the correction of the incipient separation angle as predicted by the theory is also given.Comment: 34 pages; 9 figure

Light-like noncommutativity and duality from open strings/branes

In this paper we perform some non-trivial tests for the recently obtained open membrane/D-brane metrics and `generalized' noncommutativity parameters using Dp/NS5/M5-branes which have been deformed by light-like fields. The results obtained give further evidence that these open membrane/D-brane metrics and `generalized' noncommutativity parameters are correct. Further, we use the open brane data and supergravity duals to obtain more information about non-gravitational theories with light-like noncommutativity, or `generalized' light-like noncommutativity. In particular, we investigate various duality relations (strong coupling limits). In the light-like case we also comment on the relation between open membrane data (open membrane metric etc.) in six dimensions and open string data in five dimensions. Finally, we investigate the strong coupling limit (high energy limit) of five dimensional NCYM with \Theta^{12}=\Theta^{34}. In particular, we find that this NCYM theory can be UV completed by a DLCQ compactification of M-theory.Comment: 24 pages, Latex. v2:Comments and references added. v3:Version published in JHE

AdS_3 OM theory and the self-dual string or Membranes ending on the Five-brane

We describe properties of the M-theory five-brane containing $Q$ coincident self-dual strings on its worldvolume. This is the five-brane description of Q membranes ending on the five-brane. In particular, we consider a Maldacena-like low energy limit in the six-dimensional worldvolume which yields a near `horizon' description of the self-dual string using light open membranes, i.e. OM theory, in an AdS_3 x S^3 geometry.Comment: 13 pages, latex, v2: corrected open membrane metric prefactor + typo