Mass Spectrum in SQCD and Problems with the Seiberg Duality. Another Scenario

N=1 SQCD with SU(N_c) colors and N_F flavors of light quarks is considered within the dynamical scenario which assumes that quarks can be in two different phases only. These are: a) either the HQ (heavy quark) phase where they are confined, b) or they are higgsed, at the appropriate values of parameters of the Lagrangian. The mass spectra of this (direct) theory and its Seiberg's dual are obtained and compared, for quarks of equal or unequal masses. It is shown that in all cases when there is the additional small parameter at hand (it is 0<(3N_c-N_F)/N_F << 1 for the direct theory, or its analog 0<(2N_F-3N_c)/N_F << 1 for the dual one), the mass spectra of the direct and dual theories are parametrically different. A number of other regimes are also considered.Comment: 30 pages, purely technical improvements for readers convenienc

Light Cone Sum Rules for the pi0-gamma*-gamma Form Factor Revisited

We provide a theoretical update of the calculations of the pi0-gamma*-gamma form factor in the LCSR framework, including up to six polynomials in the conformal expansion of the pion distribution amplitude and taking into account twist-six corrections related to the photon emission at large distances. The results are compared with the calculations of the B-> pi l nu decay and pion electromagnetic form factors in the same framework. Our conclusion is that the recent BaBar measurements of the pi0-gamma*-gamma form factor at large momentum transfers are consistent with QCD, although they do suggest that the pion DA may have more structure than usually assumed.Comment: 20 pages, 14 figures, 5 table

Mass corrections in J/ψ→BBˉJ/\psi \to B\bar B decay and the role of distribution amplitudes

We consider mass correction effects on the polar angular distribution of a baryon--antibaryon pair created in the chain decay process $e^-e^+ \to J/\psi \to B\bar B$, generalizing a previous analysis of Carimalo. We show the relevance of the features of the baryon distribution amplitudes and estimate the electromagnetic corrections to the QCD results.Comment: 26 pages + 3 figures, REVTEX 3.0, figures appended as uuencoded, tar-compressed postscript fil

Periodic and Quasi-Periodic Compensation Strategies of Extreme Outages caused by Polarization Mode Dispersion and Amplifier Noise

Effect of birefringent disorder on the Bit Error Rate (BER) in an optical fiber telecommunication system subject to amplifier noise may lead to extreme outages, related to anomalously large values of BER. We analyze the Probability Distribution Function (PDF) of BER for various strategies of Polarization Mode Dispersion (PMD) compensation. A compensation method is proposed that is capable of more efficient extreme outages suppression, which leads to substantial improvement of the fiber system performance.Comment: 3 pages, 1 figure, Submitted to IEEE Photonics Letter

Rejection of randomly coinciding events in ZnMoO4_4 scintillating bolometers

Random coincidence of events (particularly from two neutrino double beta decay) could be one of the main sources of background in the search for neutrinoless double beta decay with cryogenic bolometers due to their poor time resolution. Pulse-shape discrimination by using front edge analysis, mean-time and $\chi^2$ methods was applied to discriminate randomly coinciding events in ZnMoO$_4$ cryogenic scintillating bolometers. These events can be effectively rejected at the level of 99% by the analysis of the heat signals with rise-time of about 14 ms and signal-to-noise ratio of 900, and at the level of 92% by the analysis of the light signals with rise-time of about 3 ms and signal-to-noise ratio of 30, under the requirement to detect 95% of single events. These rejection efficiencies are compatible with extremely low background levels in the region of interest of neutrinoless double beta decay of $^{100}$Mo for enriched ZnMoO$_4$ detectors, of the order of $10^{-4}$ counts/(y keV kg). Pulse-shape parameters have been chosen on the basis of the performance of a real massive ZnMoO$_4$ scintillating bolometer. Importance of the signal-to-noise ratio, correct finding of the signal start and choice of an appropriate sampling frequency are discussed

The ρ\rho Meson Light-Cone Distribution Amplitudes of Leading Twist Revisited

We give a complete re-analysis of the leading twist quark-antiquark light-cone distribution amplitudes of longitudinal and transverse $\rho$ mesons. We derive Wandzura-Wilczek type relations between different distributions and update the coefficients in their conformal expansion using QCD sum rules including next-to-leading order radiative corrections. We find that the distribution amplitudes of quarks inside longitudinally and transversely polarized $\rho$ mesons have a similar shape, which is in contradiction to previous analyses.Comment: 21 pages, latex2e, requires a4wide.sty and epsf.sty, 6 PS figures include

Fermions and Loops on Graphs. II. Monomer-Dimer Model as Series of Determinants

We continue the discussion of the fermion models on graphs that started in the first paper of the series. Here we introduce a Graphical Gauge Model (GGM) and show that : (a) it can be stated as an average/sum of a determinant defined on the graph over $\mathbb{Z}_{2}$ (binary) gauge field; (b) it is equivalent to the Monomer-Dimer (MD) model on the graph; (c) the partition function of the model allows an explicit expression in terms of a series over disjoint directed cycles, where each term is a product of local contributions along the cycle and the determinant of a matrix defined on the remainder of the graph (excluding the cycle). We also establish a relation between the MD model on the graph and the determinant series, discussed in the first paper, however, considered using simple non-Belief-Propagation choice of the gauge. We conclude with a discussion of possible analytic and algorithmic consequences of these results, as well as related questions and challenges.Comment: 11 pages, 2 figures; misprints correcte

Fermions and Loops on Graphs. I. Loop Calculus for Determinant

This paper is the first in the series devoted to evaluation of the partition function in statistical models on graphs with loops in terms of the Berezin/fermion integrals. The paper focuses on a representation of the determinant of a square matrix in terms of a finite series, where each term corresponds to a loop on the graph. The representation is based on a fermion version of the Loop Calculus, previously introduced by the authors for graphical models with finite alphabets. Our construction contains two levels. First, we represent the determinant in terms of an integral over anti-commuting Grassman variables, with some reparametrization/gauge freedom hidden in the formulation. Second, we show that a special choice of the gauge, called BP (Bethe-Peierls or Belief Propagation) gauge, yields the desired loop representation. The set of gauge-fixing BP conditions is equivalent to the Gaussian BP equations, discussed in the past as efficient (linear scaling) heuristics for estimating the covariance of a sparse positive matrix.Comment: 11 pages, 1 figure; misprints correcte

Pion light cone wave function in the non-local NJL model

We use the simple instanton motivated NJL-type model to calculate the leading twist pion light cone wave function. The model consists in employing the momentum dependent quark mass in the quark loop entering the definition of the wave function. The result is analytical up to a solution of a certain algebraic equation. Various properties including the kT dependence of the pion wave function are discussed. The resulting kT integrated wave function is not asymptotic and is in agreement with recent analysis of the CLEO data.Comment: 9 pages, 12 figures, formulas (23-25) corrected, typos correcte

An Interesting Charmonium State Formation and Decay : ppˉ→1D2→1P1γp \bar p \to ^1D_2 \to ^1P_1 \gamma

Massless perturbative QCD forbids, at leading order, the exclusive annihilation of proton-antiproton into some charmonium states, which, however, have been observed in the $p\bar p$ channel, indicating the significance of higher order and non perturbative effects in the few GeV energy region. The most well known cases are those of the $^1S_0$ ($\eta_c$) and the $^1P_1$. The case of the $^1D_2$ is considered here and a way of detecting such a state through its typical angular distribution in the radiative decay $^1D_2 \to$ $^1P_1 \gamma$ is suggested. Estimates of the branching ratio $BR(^1D_2 \to p\bar p)$, as given by a quark-diquark model of the nucleon, mass corrections and an instanton induced process are presented.Comment: 9 pages (no figures), Plain TeX, CBPF-NF-014/94, INFNCA-TH-94-