Unitary Structure of the QCD Sum Rules and KYN and KY\Xi Couplings

New relations between QCD Borel sum rules for strong coupling constants of K-mesons to baryons are derived. It is shown that starting from the sum rule for the coupling constants $g_{\pi\Sigma\Sigma}$ and $g_{\pi\Sigma\Lambda}$ it is straightforward to obtain corresponding sum rules for the $g_{K Y N}$, $g_{K Y \Xi}$ couplings, $Y=\Sigma,\Lambda$.Comment: 7 pages, 2 tables, International Workshop on Quantum Chromodynamics:Theory and Experiment, QCD@Work-2005, Coversano(Bari, Italy), 16-20 June, 200

Instabilities for a relativistic electron beam interacting with a laser irradiated plasma

The effects of a radiation field (RF) on the unstable modes developed in relativistic electron beam--plasma interaction are investigated assuming that $\omega_{0} >\omega_{p}$, where $\omega_{0}$ is the frequency of the RF and $\omega_{p}$ is the plasma frequency. These unstable modes are parametrically coupled to each other due to the RF and are a mix between two--stream and parametric instabilities. The dispersion equations are derived by the linearization of the kinetic equations for a beam--plasma system as well as the Maxwell equations. In order to highlight the effect of the radiation field we present a comparison of our analytical and numerical results obtained for nonzero RF with those for vanishing RF. Assuming that the drift velocity $\mathbf{u}_{b}$ of the beam is parallel to the wave vector $\mathbf{k}$ of the excitations two particular transversal and parallel configurations of the polarization vector $\mathbf{E}_{0}$ of the RF with respect to $\mathbf{k}$ are considered in detail. It is shown that in both geometries resonant and nonresonant couplings between different modes are possible. The largest growth rates are expected at the transversal configuration when $\mathbf{E}_{0}$ is perpendicular to $\mathbf{k}$. In this case it is demonstrated that in general the spectrum of the unstable modes in $\omega$--$k$ plane is split into two distinct domains with long and short wavelengths, where the unstable modes are mainly sensitive to the beam or the RF parameters, respectively. In parallel configuration, $\mathbf{E}_{0} \parallel \mathbf{k}$, and at short wavelengths the growth rates of the unstable modes are sensitive to both beam and RF parameters remaining insensitive to the RF at long wavelengths.Comment: 23 pages, 5 figure

QCD sum rules for D and B mesons in nuclear matter

QCD sum rules for D and B mesons embedded in cold nuclear matter are evaluated. We quantify the mass splitting of D - D-bar and B - B-bar mesons as a function of the nuclear matter density; extrapolated to saturation density it is in the order of 60 and 130 MeV driven essentially by the condensates , and . The genuine chiral condensate , amplified by heavy-quark masses, enters the Borel transformed sum rules for the mass splitting beyond linear density dependence. Including strange quark condensates reveals a umerically smaller and opposite effect for the Ds - Ds-bar mass splitting.Comment: 16 pages, 8 figures, to be published; a broader range of condensate values is discussed (v2

The basis properties of eigenfunctions in the eigenvalue problem with a spectral parameter in the boundary condition

Boundary value problems for second- and fourth- order ordinary differential operators with a spectral parameter in the boundary conditions have been exten- sively studied (see, eg, [1–9]). In [3–5], such problems were associated with particular physical processes. The basis properties of the system of eigenfunctions in the Sturm–Liouville problem with a spectral param- eter in the boundary conditions were studied in various function spaces in [7–9]. The existence of eigenvalues, estimate for eigenvalues and eigenfunctions, and expansion theorems for fourth-order operators with a spectral parameter in the boundary condition were con- sidered in [1, 6] … This paper deals with the basis properties in Lp(0, l) (1 < p < ∞) of the system of eigenfunctions of boundary value problem (1), (2)

Some Spectral Properties of a Boundary Value Problem with a Spectral Parameter in the Boundary Condition

Along with problem (1),(2), we consider boundary value problem (1),(2a),(2b),(2c),(2d'). For the latter problem, the oscillation properties of its eigenfunctions corresponding to positive eigenvalues were studied in detail in [8]. In this context, the following two cases were excluded from consideration in [8]:(i) α= γ= 0 and β= δ=; and (ii) the arbitrary three parameters out of α, β, γ, and δ are equal to. Note that, in fact, only the case β= δ= is to be excluded. ψ cot r' 2ψ θ ϕ+() sin sin q 1

Lepton polarization correlations in B→K∗τ−τ+B \to K^* \tau^- \tau^+

In this work we will study the polarizations of both leptons ($\tau$) in the decay channel $B\to K^* \tau^- \tau^+$. In the case of the dileptonic inclusive decay $B\to K^* \ell^- \ell^+$, where apart from the polarization asymmetries of single lepton $\ell$, one can also observe the polarization asymmetries of both leptons simultaneously. If this sort of measurement is possible then we can have, apart from decay rate, FB asymmetry and the six single lepton polarization asymmetries (three each for $\ell^-$ and $\ell^+$), nine more double polarization asymmetries. This will give us a very useful tool in more strict testing of SM and the physics beyond. We discuss the double polarization asymmetries of $\tau$ leptons in the decay mode $B\to K^* \tau^- \tau^+$ within the SM and the Minimal Supersymmetric extensions of it.Comment: 21 pages, 21 figures; version to match paper to appear in PR

On the Basis Property of the System of Eigenfunctions of a Spectral Problem with Spectral Parameter in the Boundary Condition

In the present paper, we study basis properties of the system of eigenfunctions of the boundary value problem (1.1),(1.2) in the spaces Lp (0, l)(1< p<∞). Boundary value problems for second-and fourth-order ordinary differential operators with a spectral parameter in boundary conditions were studied in a series of papers (eg, see [1–17]). A number of problems in mathematical physics can be reduced to such problems (eg, see [2–10]). Basis properties of the system of eigenfunctions of the Sturm–Liouville problem with a spectral parameter in the boundary condition were studied in [10–16] in various function spaces, and the existence of eigenvalues, estimates of eigenvalues and eigenfunctions, and expansion theorems were considered in [1, 6, 8, 9] for fourth-order ordinary differential operators with a spectral parameter in a boundary condition

Vacuum Fluctuations of a massless spin-1/2 field around multiple cosmic strings

We study the interaction of a massless quantized spinor field with the gravitational filed of N parallel static cosmic strings by using a perturbative approach. We show that the presence of more than one cosmic string gives rise to an additional contribution to the energy density of vacuum fluctuations, thereby leading to a vacuum force attraction between two parallel cosmic strings.Comment: Class. Quantum Grav. 14(1997) 321

New physics effects to the lepton polarizations in the B -> K l^+ l^- decay

Using the general, model independent form of the effective Hamiltonian, the general expressions of the longitudinal, normal and transversal polarization asymmetries for (l^-) and (l^+) and combinations of them for the exclusive (B -> K l^+ l^-) decay are found. The sensitivity of lepton polarizations and their combinations on new Wilson coefficients are studied. It is found that there exist regions of Wilson coefficients for which the branching ratio coincides with the Standard Model result while the lepton polarizations differ substantially from the standard model prediction. Hence, studying lepton polarization in these regions of new Wilson coefficients can serve as a promising tool for establishing new physics beyond the Standard Model.Comment: 18 pp, 14 figures (postscript formatted), LaTex formatte

Specific heat and magnetocaloric effect in Pr1-xAgxMnO3 manganites

The magnetocaloric effect in alternating magnetic fields has been investigated in Pr1-xAgxMnO3 manganites with x=0.05-0.25. The stepwise reversal of the sign of the magnetocaloric effect has been revealed in a weakly doped sample (x=0.05) at low temperatures (~80 K). This reversal is attributed to the coexistence of the ferromagnetic and canted antiferromagnetic phases with different critical temperatures.Comment: 4 pages, 4 figure