What is the Physics behind the 3He-4He Anomaly ?

We show that coalescence of nucleons emitted prior to thermalization in highly excited nuclei can explain the anomaly of kinetic energies of helium clusters. A new coalescence algorithm has been included into the statistical approach to nuclear reactions formerly used to describe intermediate mass fragment production.Comment: 5 pages, 4 figures, accepted at Eur. Phys.

A note on spectator effects and quark-hadron duality in inclusive beauty decays

In this paper, we evaluate the expectation values of four-quark operators for the inclusive beauty decays from the differences in the inclusive total decay rates, assuming that the heavy quark expansion converges at $O(1/m^3)$. The obtained expectation values yeilds the ratio $\tau(\Lambda_b)/\tau(B)$ close to the experimental onee. We further point out that the quark-hadron duality violation would be rather small allowing predictions of inclusive quantities.Comment: 5 pages, typos corrected, version to be published in PL

Phenomenology of B -> pi pi, pi K Decays at O(alpha^2 beta_0) in QCD Factorization

We study O(alpha^2 beta_0) perturbative corrections to matrix elements entering two-body exclusive decays of the form B -> pi pi, pi K in the QCD factorization formalism, including chirally enhanced power corrections, and discuss the effect of these corrections on direct CP asymmetries, which receive their first contribution at O(alpha). We find that the O(alpha^2 beta_0) corrections are often as large as the O(alpha) corrections. We find large uncertainties due to renormalization scale dependence as well as poor knowledge of the non-perturbative parameters. We assess the effect of the perturbative corrections on the direct CP violation parameters of B -> pi^+ pi^-.Comment: 27 pages, 5 figures. Updated input parameters and added citations; expanded discussio

Infrared singularities of scattering amplitudes in perturbative QCD

An exact formula is derived for the infrared singularities of dimensionally regularized scattering amplitudes in massless QCD with an arbitrary number of legs, valid at any number of loops. It is based on the conjecture that the anomalous-dimension matrix of n-jet operators in soft-collinear effective theory contains only a single non-trivial color structure, whose coefficient is the cusp anomalous dimension of Wilson loops with light-like segments. Its color-diagonal part is characterized by two anomalous dimensions, which are extracted to three-loop order from known perturbative results for the quark and gluon form factors. This allows us to predict the three-loop coefficients of all 1/epsilon^k poles for an arbitrary n-parton scattering amplitudes, generalizing existing two-loop results.Comment: 4 pages; v2: typo in eq. (12) fixed, references updated; v3: additional term in (12

Flavor Physics in the Randall-Sundrum Model: I. Theoretical Setup and Electroweak Precision Tests

A complete discussion of tree-level flavor-changing effects in the Randall-Sundrum (RS) model with brane-localized Higgs sector and bulk gauge and matter fields is presented. The bulk equations of motion for the gauge and fermion fields, supplemented by boundary conditions taking into account the couplings to the Higgs sector, are solved exactly. For gauge fields the Kaluza-Klein (KK) decomposition is performed in a covariant R_xi gauge. For fermions the mixing between different generations is included in a completely general way. The hierarchies observed in the fermion spectrum and the quark mixing matrix are explained naturally in terms of anarchic five-dimensional Yukawa matrices and wave-function overlap integrals. Detailed studies of the flavor-changing couplings of the Higgs boson and of gauge bosons and their KK excitations are performed, including in particular the couplings of the standard W and Z bosons. A careful analysis of electroweak precision observables including the S and T parameters and the Zbb couplings shows that the simplest RS model containing only Standard Model particles and their KK excitations is consistent with all experimental bounds for a KK scale as low as a few TeV, if one allows for a heavy Higgs boson and/or for an ultra-violet cutoff below the Planck scale. The study of flavor-changing effects includes analyses of the non-unitarity of the quark mixing matrix, anomalous right-handed couplings of the W bosons, tree-level flavor-changing neutral current couplings of the Z and Higgs bosons, the rare decays t-->c(u)+Z and t-->c(u)+h, and the flavor mixing among KK fermions. The results obtained in this work form the basis for general calculations of flavor-changing processes in the RS model and its extensions.Comment: 70 pages, 12 figures. v2: Incorrect treatment of phases in zero-mode approximation corrected, and discussion of electroweak precision tests modified. v3: Additional minor modifications and typos corrected; version published in JHE

Improved Currents for Heavy Quarks

We discuss lattice artifacts for matrix elements of hadrons containing one or more heavy quark. In particular, we analyze interrelations between lattice artifacts and the $1/m_Q$ expansion. The implications for calculations of heavy-light decay constants and of semi-leptonic form factors are discussed.Comment: 3 pages, no figures, uuencoded PostScript, proceedings of Lattice '94. LaTeX at ftp://fnth06.fnal.gov/pub/Fermilab-Pub/95.00

Decays of bottom mesons emitting tensor meson in final state using ISGW II model

In this paper, we investigate phenomenologically two-body weak decays of the bottom mesons emitting pseudoscalar/vector meson and a tensor meson. Form factors are obtained using the improved ISGW II model. Consequently, branching ratios for the CKM-favored and CKM-suppressed decays are calculated.Comment: 32 pages, to be published in Phys. Rev.

How reliable are the HQET-sum rule predictions?

We test the internal consistencies and the reliability of the existing estimates of the decay constant $f_B$ in the static limit, the meson-quark mass gap $\bar \Lambda$ and the kinetic energy $K$ of a heavy quark obtained from the heavy quark effective theory (HQET)-sum rules. Finite energy local duality sum rules (FESR) have also been used to fix $approximatively$ the value of the continuum energy and to study the correlations among these different parameters. Then, we deduce to two-loop accuracy: \bl=(0.65\pm 0.05) GeV, $K=-(0.5 \pm 0.2)$GeV^2$, implying the value of the pole mass in HQET:$M_b= (4.61 \pm 0.05)$GeV. By combining the results from the sum rules in HQET and in the full theory, we obtain$f_B^\infty=(1.98 \pm 0.31)f_\pi$and the quadratic mass dependence of the pseudoscalar decay constant:$f_P\sqrt{M_P}=(0.33 \pm 0.06)$GeV$^{3/2}\als^{1/\beta_1}2}\als^{1/\beta_1 1-2\als/3\pi-1.1/M_Q +0.7/M_Q^2 .$Comment: PS file, figures available by reques

A Consistent Calculation of Heavy Meson Decay Constants and Transition Wave Functions in the Complete HQEFT

Within the complete heavy quark effective field theory (HQEFT), the QCD sum rule approach is used to evaluate the decay constants including 1/m_Q corrections and the Isgur-Wise function and other additional important wave functions concerned at 1/m_Q for the heavy-light mesons. The 1/m_Q corrections to the scaling law f_M \sim F/\sqrt{m_M} are found to be small in HQEFT, which demonstrates again the validity of 1/m_Q expansion in HQEFT. It is also shown that the residual momentum v.k of heavy quark within hadrons does be around the binding energy \bar{\Lambda} of the heavy hadrons. The calculations presented in this paper provide a consistent check on the HQEFT and shows that the HQEFT is more reliable than the usual HQET for describing a slightly off-mass shell heavy quark within hadron as the usual HQET seems to lead to the breakdown of 1/m_Q expansion in evaluating the meson decay constants. It is emphasized that the introduction of the `dressed heavy quark' mass is useful for the heavy-light mesons (Qq) with m_Q >> \bar{\Lambda} >> m_q, while for heavy-heavy bound states (\psi_1\psi_2) with masses m_1, m_2 >> \bar{\Lambda}, like bottom-charm hadrons or similarly for muonium in QED, one needs to treat both particles as heavy effective particles via 1/m_1 and 1/m_2 expansions and redefine the effective bound states and modified `dressed heavy quark' masses within the HQEFT.Comment: 20 pages, revtex, 22 figures, axodraw.sty, two irrelevant figures are moved awa