Photosensitive bismuth ions in lead tungstate

Electron paramagnetic resonance (EPR) signals of Bi2+ ions have been detected in the EPR spectrum of manganese-, bismuth-, and tin-doped PbWO4 single-crystals irradiated by xenon and mercury lamps at 100 K. The parameters of the Zeeman, hyperfine, and superhyperfine interactions and the localization of Bi2+ ions have been determined. © 2013 Pleiades Publishing, Ltd

Paramagnetic defects in manganese-doped lead tungstate

In manganese-doped PbWO4 crystals, low-intensity signals of triclinic clusters Mn4+-VO and Fe3+-VPb have been revealed in addition to signals of Mn2+ tetragonal centers. The Mn4+-VO cluster is formed by a Mn4+ ion in the W6+ position, which is associated with a vacancy of the nearest neighbor O2-ion, and the Fe3+-VPb cluster consists of a Fe3+ ion substituting for Pb2+ with a local compensation of by a lead vacancy. It has been shown that, in PbWO4: Mn, there is also a small amount of Mn4+ tetragonal centers located in the Pb2+ position with a nonlocal compensation of an excess charge. © 2013 Pleiades Publishing, Ltd

b→sγb \to s \gamma decays in the Left-Right Symmetric Model

We consider $b \to s \gamma$ decays in the Left-Right Symmetric Model. Values of observables sensitive to chiral structure such as the $\Lambda$ polarization in the $\Lambda_b \to \Lambda \gamma$ decays and the mixing-induced CP asymmetries in the $B_{d,s} \to M^0 \gamma$ decays can deviate in the LRSM significantly from the SM values. The combined analysis of $P_\Lambda$ and $A_{CP}$ as well as ${\cal BR}(b \to s \gamma)$ can be used to determine the model parameters.Comment: 16 pages with 7 figures, Version to be published in PR

More Model-Independent Analysis of b->s Processes

We study model-independently the implications of non-standard scalar and pseudoscalar interactions for the decays b ->s gamma, b -> s g, b -> s l^+l^- (l=e,mu) and B_s -> mu^+ mu^-. We find sizeable renormalization effects from scalar and pseudoscalar four-quark operators in the radiative decays and at O(alpha_s) in hadronic b decays. Constraints on the Wilson coefficients of an extended operator basis are worked out. Further, the ratios R_H = BR(B -> H mu^+ mu^-)/BR(B -> H e^+ e^-), for H=K^(*), X_s, and their correlations with B_s -> mu^+ mu^- decay are investigated. We show that the Standard Model prediction for these ratios defined with the same cut on the dilepton mass for electron and muon modes, R_H= 1 + O(m^2_mu/m^2_b), has a much smaller theoretical uncertainty (<1%) than the one for the individual branching fractions. The present experimental limit R_K < 1.2 puts constraints on scalar and pseudoscalar couplings, which are similar to the ones from current data on BR(B_s -> mu^+ mu^-). We find that new physics corrections to R_{K*} and R_{X_s} can reach 13% and 10%, respectively.Comment: 28 pages, 6 figures; Table 1 updated, two refs added (to appear in PRD

b→sγb \to s \gamma Decay in SU(2)L×SU(2)R×U(1)SU(2)_L \times SU(2)_R \times U(1) Extensions of the Standard Model

The rare radiative decay $b \to s \gamma$ is studied in $SU(2)_L \times SU(2)_R \times U(1)$ extensions of the Standard Model. Matching conditions for coefficients of operators appearing in the low energy effective Hamiltonian for this process are derived, and QCD corrections to these coefficients are analyzed. The $b \to s \gamma$ decay rate is then calculated and compared with the corresponding Standard Model result. We find that observable deviations from Standard Model predictions can occur in $SU(2)_L \times SU(2)_R \times U(1)$ theories for a reasonable range of parameter values.Comment: 17 pages with 5 figures not included but available upon request, CALT-68-1893, TUM-T31-52/9

Calculation of two-loop virtual corrections to b --> s l+ l- in the standard model

We present in detail the calculation of the virtual O(alpha_s) corrections to the inclusive semi-leptonic rare decay b --> s l+ l-. We also include those O(alpha_s) bremsstrahlung contributions which cancel the infrared and mass singularities showing up in the virtual corrections. In order to avoid large resonant contributions, we restrict the invariant mass squared s of the lepton pair to the range 0.05 < s/mb^2 < 0.25. The analytic results are represented as expansions in the small parameters s/mb^2, z = mc^2/mb^2 and s/(4 mc^2). The new contributions drastically reduce the renormalization scale dependence of the decay spectrum. For the corresponding branching ratio (restricted to the above s-range) the renormalization scale uncertainty gets reduced from +/-13% to +/-6.5%.Comment: 41 pages including 9 postscript figures; in version 2 some typos and inconsistent notation correcte

NNLL corrections to the angular distribution and to the forward-backward asymmetries in b -> X_s l+ l-

We present NNLL results for the double differential decay width dGamma(b -> X_s l+ l-)/(dsh dcos(theta)), where theta is the angle between the momenta of the b-quark and the l+, measured in the rest-frame of the lepton pair. From these results we also derive NNLL results for the lepton forward-backward asymmetries. Genuinely new calculations for the combined virtual- and gluon bremsstrahlung corrections associated with the operators O_7, O_9 and O_10 are necessary. We find that the NNLL corrections drastically reduce the renormalization scale dependence of the forward-backward asymmetries. In particular, sh_0, the position at which the forward-backward asymmetries vanish, is essentially free of uncertainties due to the renormalization scale at NNLL precision. We find sh_0(NNLL)=0.162 +/- 0.005, where the error is dominated by the uncertainty in (m_c/m_b). This is to be compared with sh_0(NLL)=0.144 +/- 0.020, where the error is dominated by uncertainties due to the choice of mu.Comment: 26 pages including 11 postscript figure

The flavor puzzle in multi-Higgs models

We reconsider the flavor problem in the models with two Higgs doublets. By studying two generation toy models, we look for flavor basis independent constraints on Yukawa couplings that will give us the mass hierarchy while keeping all Yukawa couplings of the same order. We then generalize our findings to the full three generation Standard Model. We find that we need two constraints on the Yukawa couplings to generate the observed mass hierarchy, and a slight tuning of Yukawa couplings of order 10%, much less than the Standard Model. We briefly study how these constraints can be realized, and show how flavor changing currents are under control for $K-\bar{K}$ mixing in the near-decoupling limit.Comment: 26 pages, typos are corrected, references are added, the final versio

Failure of JoAnne's Global Fit to the Wilson Coefficients in Rare B Decays: A Left-Right Model Example

In the Standard Model and many of its extensions, it is well known that all of the observables associated with the rare decays $b\to s\gamma$ and $b\to s\ell^+\ell^-$ can be expressed in terms of the three Wilson coefficients, $C_{7L,9L,10L}(\mu \sim m_b)$, together with several universal kinematic functions. In particular it has been shown that the numerical values of these coefficients can be uniquely extracted by a three parameter global fit to data obtainable at future $B$-factories given sufficient integrated luminosity. In this paper we examine if such global fits are also sensitive to new operators beyond those which correspond to the above coefficients, i.e., whether is it possible that new operators can be of sufficient importance for the three parameter fit to fail and for this to be experimentally observable. Using the Left-Right Symmetric Model as an example of a scenario with an extended operator basis, we demonstrate via Monte Carlo techniques that such a possibility can indeed be realized. In some sense this potential failure of the global fit approach can actually be one of its greatest successes in identifying the existence of new physics.Comment: 30 pages, 6 figure

Left atrial strain as a predictor of atrial fibrillation in patients with asymptomatic severe aortic stenosis and preserved left ventricular systolic function

Aim. To study the structural and functional left heart parameters in patients with severe aortic stenosis (AS) and preserved ejection fraction (EF) in order to determine the risk of atrial fibrillation (AF).Material and methods. The study included 84 patients (men, 37; mean age, 68±8 years) with severe AS and EF &gt;55%. All patients had sinus rhythm and were asymptomatic. Echocardiography was performed to assess longitudinal strain of the left ventricle (LVLS), right ventricle, left atrium (LALS) and the left atrial stiffness (LAS) using the speckle tracking method. Left ventricular mass index (LVMI) and maximum left atrium volume index (LAVI) were also determined. Patients were followed up for 1 year.Results. AF was reported in 27 (32%) patients, of which 9 (33%) had asymptomatic AF episodes detected by 48-hour electrocardiography. Eighteen (67%) patients with AF felt palpitations. Patients with and without episodes of atrial fibrillation had non-significant differences in LVMI, LAVI, and LVLS. Patients with atrial fibrillation had a lower LALS and a higher LAS compared with patients without atrial fibrillation. Regression analysis revealed that LALS and LAS were independent predictors of AF.Conclusion. AF develops in about one third of asymptomatic patients with severe AS and normal EF. The development of AF predisposes to the onset of AS symptoms in most patients. LALS and LAS were predictors of AF in these patients. Identification of patients at risk of AF will allow for earlier aortic valve replacement