Determination of the magnetic susceptibility of the quark condensate using radiative heavy meson decays

We use a light-cone sum rule (LCSR) analysis of the branching ratios of radiative meson decays to contrain the value of the magnetic susceptibility of the quark condensate $\chi(\mu)$. For the first time, we use a complete set of three-particle distribution amplitudes that enables us to give a consistent prediction for the branching ratios. Furthermore we will make use of a very recent update of several non-perturbative parameters. Our final result for $\chi(\mu= 1 {\rm GeV})= 2.85 \pm 0.5 {\rm GeV}^{-2}$ (assuming asymptotic wave functions) agrees with the currently used value of $3.15 \pm 0.3 {\rm GeV}^{-2}$.Comment: 21 pages, 4 figures, references adde

Nonperturbative Corrections to Inclusive Beauty and Charm Decays: QCD versus Phenomenological Models

We present a selfconsistent method for treating nonperturbative effects in inclusive nonleptonic and semileptonic decays of heavy flavour hadrons. These effects give rise to powerlike corrections $\propto 1/m_Q^n\,$, $n \ge 2$ with $m_Q$ denoting the heavy quark mass.The leading correction to the semileptonic branching ratio occurs for n=2. It is expressed in terms of the vector-pseudoscalar mass splitting: \delta BR\ind{sl}/BR\ind{sl} \simeq BR\ind{nl}\, \cdot \,6\,(\,(M_V^2-M_P^2)/m_Q^2)\cdot (c_+^2 - c_-^2)/2N_c and yields a {\it reduction} of BR\ind{sl}. This nonperturbative correction contributes to the nonleptonic width with a sign opposite to that of the perturbative terms that are non-leading in $1/N_c$. In beauty decays the former reduces the latter by 20 \% whereas in charm decays they more or less cancel. This leads to a {\it reduction} of BR\ind{sl} by no more than 10 \% in beauty decays and by a factor of roughly two in charm decays. We confront these results with those obtained from phenomenological models of heavy flavour decays and find that such models are unable to mimic these leading corrections by a specific choice of quark masses or by invoking Fermi motion.Comment: 11 pages (2 figs are not included), Latex file, FERMILAB-PUB-92/158-T UND-HEP-92-BIG04 TPI-MINN-92/30-

ERRATUM TO: Power corrections 1/Q21/Q^2 to parton sum rules for deep inelastic scattering from polarized targets

We clarify conflicting results in the literature on coefficient functions in front of higher twist operators contributing to the parton sum rules for deep inelastic scattering from polarized targets. The necessary corrections do not affect our calculations of matrix elements, published in Phys.Lett.B242(1990)245, but change final estimates of the $\sim 1/Q^2$ contributions to Bjorken and Ellis--Jaffe sum rules.Comment: 2 pages, MPI-Ph/93-0

D^0 - D^0-bar Oscillations as a Probe of Quark-Hadron Duality

It is usually argued that the Standard Model predicts slow D^0-\bar D^0 oscillations with \Delta M_D, \Delta \Gamma_D < 10^{-3}*\Gamma_D$ and that New Physics can reveal itself through \Delta M_D exceeding 10^{-3}*\Gamma_D. It is believed that the bulk of the effect is due to long distance dynamics that cannot be described at the quark level. We point out that in general the OPE yields soft GIM suppression scaling only like (m_s/\mu_{hadr})^2 and even like m_s/\mu_{hadr} rather than m_s^4/m_c^4 of the simple quark box diagram. Such contributions can actually yield \Delta M_D, \Delta \Gamma_D \sim O(10^{-3})*\Gamma_D without invoking additional long distance effects. They are reasonably suppressed as long as the OPE and local duality are qualitatively applicable in the 1/m_c expansion. We stress the importance of improving the sensitivity on \Delta \Gamma_D as well as \Delta M_D in a dedicated fashion as a laboratory for analyzing the onset of quark-hadron duality and comment on the recent preliminary study on \Delta \Gamma_D by the FOCUS group.Comment: 15 pages, LaTeX. Revised: A reference and a few clarifications in the text are added. A few inconsistencies in equations are eliminated. We found the standard contribution to Delta M_D to differ from the expression usually quoted in the literatur

Structure and Application of ATDP Suite for Electronic System States Detection and Evolution Operator Restoration

Structure and peculiarities of the Adaptive Testing Data Processing software Suite (ATDP Suite) are presented. It is applied for dynamic characteristics restoration from experimental time series of nonlinear and unstable electronic system. Basic methods realized in ATDP Suite are demonstrated. Application of ATDP Suite for electromagnetic tests of microwave receivers demonstrated the possibility to analyze and interpret the dynamic characteristics of complex nonlinear system.Представлены структура и особенности программного пакета адаптивной тестирующей обработки данных (ATDP Suite). Он применен к восстановлению динамических характеристик из экспериментальных временных рядов нелинейной и нестабильной электронной системы. Продемонстрированы основные методы, реализованные в ATDP Suite. Применение ATDP Suite для электромагнитного тестирования СВЧ приемников показало возможность анализировать и интерпретировать динамические характеристики сложной нелинейной системы.Представлено структуру та особливості програмного пакета адаптивної тестуючої обробки даних (ATDP Suite). Його застосовано для відтворення динамічних характеристик з експериментальних часових рядів нелінійної та нестабільної електронної системи. Продемонстровано основні методи, реалізовані в ATDP Suite. Застосування ATDP Suite для електромагнітного тестування НВЧ приймачів продемонструвало можливість аналізувати та інтерпретувати динамічні характеристики складної нелінійної системи

Inclusive Semileptonic Decays in QCD Including Lepton Mass Effects

Starting from an Operator Product Expansion in the Heavy Quark Effective Theory up to order 1/m_b^2 we calculate the inclusive semileptonic decays of unpolarized bottom hadrons including lepton mass effects. We calculate the differential decay spectra d\Gamma/(dE_\tau ), and the total decay rate for B meson decays to final states containing a \tau lepton.Comment: 16 pages + 4 figs. appended in uuencoded form, LaTeX, MZ-TH/93-3

Decays of the ρ^(1−+)\hat\rho(1^{-+}) Exotic Hybrid and η\eta-η′\eta' Mixing

QCD sum-rules are used to calculate the $\hat\rho(1^{-+})\to\pi\eta, \pi\eta'$ decay widths of the exotic hybrid in two different $\eta-\eta'$ mixing schemes. In the conventional flavour octet-singlet mixing scheme, the decay widths are both found to be small, while in the recently-proposed quark mixing scheme, the decay width $\Gamma_{\hat\rho\to\eta\pi}\approx 250 MeV$ is large compared with the decay width $\Gamma_{\hat\rho\to\eta^\prime\pi}\approx 20 MeV$. These results provide some insight into $\eta$-$\eta'$ mixing and hybrid decay features.Comment: latex2e, 11 pages with 4 embedded eps figures. v 2 corrects reference [5] and minor error in equation (11

Spin Effects in Two Quark System and Mixed States

Based on the numeric solution of a system of coupled channels for vector mesons ($S$- and $D$-waves mixing) and for tensor mesons ($P$- and $F$-waves mixing) mass spectrum and wave functions of a family of vector mesons $q\bar{q}$ in triplet states are obtained. The calculations are performed using a well known Cornell potential with a mixed Lorentz-structure of the confinement term. The spin-dependent part of the potential is taken from the Breit-Fermi approach. The effect of singular terms of potential is considered in the framework of the perturbation theory and by a configuration interaction approach (CIA), modified for a system of coupled equations. It is shown that even a small contribution of the $D$-wave to be very important at the calculation of certain characteristics of the meson states.Comment: 12 pages, LaTe

Improved Determination of the Mass of the 1−+1^{-+} Light Hybrid Meson From QCD Sum Rules

We calculate the next-to-leading order (NLO) $\alpha_s$-corrections to the contributions of the condensates $$ and $^2$ in the current-current correlator of the hybrid current g\barq(x)\gamma_{\nu}iF_{\mu\nu}^aT^aq(x) using the external field method in Feynman gauge. After incorporating these NLO contributions into the Laplace sum-rules, the mass of the $J^{PC}$=$1^{-+}$ light hybrid meson is recalculated using the QCD sum rule approach. We find that the sum rules exhibit enhanced stability when the NLO $\alpha_s$-corrections are included in the sum rule analysis, resulting in a $1^{-+}$ light hybrid meson mass of approximately 1.6 GeV.Comment: revtex4, 10 pages, 7 eps figures embedded in manuscrip

Impact of the carrier relaxation paths on two-state operation in quantum dot lasers

We study InGaAs QD laser operating simultaneously at ground (GS) and excited (ES) states under 30ns pulsed-pumping and distinguish three regimes of operation depending on the pump current and the carrier relaxation pathways. An increased current leads to an increase in ES intensity and to a decrease in GS intensity (or saturation) for low pump range, as typical for the cascade-like pathway. Both the GS and ES intensities are steadily increased for high current ranges, which prove the dominance of the direct capture pathway. The relaxation oscillations are not pronounced for these ranges. For the mediate currents, the interplay between the both pathways leads to the damped large amplitude relaxation oscillations with significant deviation of the relaxation oscillation frequency from the initial value during the pulse