Calculation of spectroscopic constants and radiative parameters for A1Σ u+ -X1Σ g+ and B1Πu-X1Σ g+ electronic transitions of sodium dimer

Vibrational, rotational, and centrifugal spectroscopic constants and radiative parameters, i.e., the Einstein coefficients, oscillator strengths, and wave numbers for vibrational transitions in electronic systems of bands A ¹Σ _u ⁺-X ¹Σ _g ⁺ (0 ≤ v′ ≤ 25; 0 ≤ v″ ≤ 44), B ¹Π _u -X ¹Σ _g ⁺ (0 ≤ v′ ≤ 29; 0 ≤ v″ ≤ 47), and the radiative lifetimes for the vibrational levels of excited states of the sodium dimer, are calculated. The calculations are carried out based on semiempirical potential curves constructed in this study. The calculated spectroscopic constants and radiative lifetimes are compared to the experimental values.     

Cross section and rate coefficient calculations for electron impact excitation, ionisation and dissociation of the X 1Σg+, c 3Πu, a 3Σ g+, e 3Σu+ and B′1Σu+ states of H2

The weighted total cross section (WTCS) theory has been applied to the electron-H₂ collision to obtain excitation, ionisation and dissociation cross section and rate coefficients of the X ¹S_g⁺^{1}\!\Sigma _{g}^{+}, c ³P_u^{3}\!\Pi _{u}, a ³S_g⁺^{3}\!\Sigma _{g}^{+}, e $^{3}\!\Sigma _{u}^{+}$^{3}\!\Sigma _{u}^{+} and B^{′ 1}S_u⁺^{1}\!\Sigma _{u}^{+} states. Calculation has been performed in the temperature range 1500 K–15000 K. Rate coefficients are calculated from WTCS assuming Maxwellian energy distribution functions for electrons and heavy particles. Thermal equilibrium results are presented and fitting parameters (a, b and c) are given for each reaction rate coefficient: k(θ) = a (θ^b) exp(-c/θ).     

Charge-transfer reactions in clusters excited with synchrotron radiation

Charge-transfer reactions are observed in a photoluminescence study of NF₃\rm NF_3-doped free krypton clusters. They show up in emissions from Kr⁺F^-\rm Kr^{+}F^{-}free excimers ejected from the clusters, and from excited Kr₂⁺F^-\rm Kr_2^{+}F^{-}and Kr₂⁺(NF₃)_m^-{\rm Kr}_2^{+}({\rm NF}_3)_m^{-} (m 3(m\geq 1) solvated in the clusters. The results show that reaction dynamics in clusters differs considerably from that in the gas and solid phases.     

Intensity distribution in the bands of theD 1Π →X 1Σ+ system of SnO

Relative integrated intensities of the bands of theD ¹Π →X ¹Σ⁺ system of SnO have been measured by the technique of heterochromatic photographic photometry. Using the Rydberg-Klein-Rees Franck-Condon factors andr-centroids, the variation of electronic transition momentR _e with the internuclear separationr is found to beR _e (r)=const. (0.564r−1) in the range of 1.865 A≤r≤2.041A. The relative band strengths are derived. Effective vibrational temperature of the source is found to be 2559 K.     

Analysis of the $ {\frac{{1}}{{2}}}$+ doubly heavy baryon states with QCD sum rules

In this paper, we study the \frac12 {\frac{{1}}{{2}}} ⁺ doubly heavy baryon states W_QQ \Omega_{{QQ}}^{} and X_QQ \Xi_{{QQ}}^{} by subtracting the contributions from the corresponding \frac12 {\frac{{1}}{{2}}} ^- doubly heavy baryon states with QCD sum rules, and make reasonable predictions for their masses. Those doubly heavy baryon states may be observed at Tevatron, LHCb and PANDA.     

Transversity in hard exclusive electroproduction of pseudoscalar mesons

Estimates for electroproduction of pseudoscalar mesons at small values of skewness are presented. Cross-sections and asymmetries for these processes are calculated within the handbag approach which is based on factorization in hard parton subprocesses and soft generalized parton distributions (GPDs). The latter are constructed from double distributions. Transversity GPDs are taken into account; they are accompanied by twist-3 meson wave functions. For most pseudoscalar-meson channels a combination of ˜_T and [`(E)]_T \bar{{E}}_{T}^{} plays a particularly prominent role. This combination of GPDs, which we constrain by moments obtained from lattice QCD, leads, with the exception of the p⁺ \pi^{+}_{} and h^￠ \eta^{\prime}_{} channels, to large transverse cross-sections.     

Ultrafast delocalization of hydrogen atoms in allene in intense laser fields

Ultrafast delocalization of hydrogen atoms in allene (CH₂=C=CH₂) induced by intense laser fields was investigated by the Coulomb explosion coincidence momentum imaging method. On the basis of the kinetic energy distributions of the fragment ions produced through the two three-body Coulomb explosion pathways, C₃H₄³⁺ ? H⁺ + CH⁺ + C₂H₂⁺\mathrm{C}_{3}\mathrm{H}_{4}^{3+} \rightarrow \mathrm{H}^{+} + \mathrm{CH}^{+} + \mathrm{C}_{2}\mathrm{H}_{2}^{+} and C₃H₄³⁺ ? H⁺ + C₂H⁺ +CH₂⁺\mathrm{C}_{3}\mathrm{H}_{4}^{3+} \rightarrow \mathrm{H}^{+} + \mathrm{C}_{2}\mathrm{H}^{+} +\mathrm{CH}_{2}^{+}, and the proton maps for both pathways, it was shown that the decomposition proceeds in a stepwise manner as well as in a concerted manner. The time scale of the hydrogen migration within an allene molecule was estimated to be ∼20 fs.     

Application of CI expansion techniques to the computation of two-photon absorptivities

Summary We show how conventional linear expansion techniques for both electronic and vibrational wave functions can be used for the computation of matrix elements governing the two-photon absorption probability in molecules. In particular, the²Σ⁺ A←²∏X transition matrix elements of OH and the¹Σ _g ⁺ E,F←¹Σ _g ⁺ X of H₂are computed using 1) the sum over states in the Born-Oppenheimer approximation with inclusion of vibrational wave functions, 2) solution of perturbation theory equations by expansion in the CI basis at fixed nuclei, followed by a kind of vibrational averaging. The results are compared with experiment and discussed. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Dielectric relaxation and ionic conductivity studies of Ag<Subscript>2</Subscript>ZnP<Subscript>2</Subscript>O<Subscript>7</Subscript>

The complex impedance of the Ag₂ZnP₂O₇ compound has been investigated in the temperature range 419–557 K and in the frequency range 200 Hz–5 MHz. The Z′ and Z′ versus frequency plots are well fitted to an equivalent circuit model. Dielectric data were analyzed using complex electrical modulus M* for the sample at various temperatures. The modulus plot can be characterized by full width at half-height or in terms of a non-exponential decay function f( \textt ) = exp( - \textt/t )^b \phi \left( {\text{t}} \right) = \exp {\left( { - {\text{t}}/\tau } \right)^\beta } . The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law: s( w) = s_\textdc + \textAwⁿ \sigma \left( \omega \right) = {\sigma_{\text{dc}}} + {\text{A}}{\omega^n} . The conductivity σ _dc follows the Arrhenius relation. The near value of activation energies obtained from the analysis of M″, conductivity data, and equivalent circuit confirms that the transport is through ion hopping mechanism dominated by the motion of the Ag⁺ ions in the structure of the investigated material.     

Simple determination of Na2 scattering lengths using observed bound levels at the ground state asymptote

A simple model is developed to determine a scattering length from the experimental values of the energy of the last, least bound, vibrational levels of the ground state, either ¹S_g⁺^1\Sigma _g^{+} or ³S_u⁺^3\Sigma _u^{+},of an alkali dimer. It is based on an extrapolation of the positions of the few outermost nodes of the bound vibrational wave functions towards the dissociation threshold. It uses the asymptotic part of the molecular potential only. The method is applied to recently measured levels at the asymptote (3s+3s) of Na₂. We obtain precise values for the two scattering lengths respectively associated to the dissociation limits F₁=F₂=1,F=2 (55.1±\pm 1.6 a₀) and F₁=F₂=1,F=0 (50.0±\pm 1.6 a₀); the first value corresponds to the a_1,-1 scattering length usually considered in cold collisions. The extrapolation procedure is also applied to Li₂, using existing experimental data.     

Electromagnetic structure of W± bosons in the e–e+ → W+W– reaction

A model-independent analysis of anomalous gauge coupling constants of W ^± bosons is presented and the corresponding restrictions on them and on the electromagnetic characteristics of W ^± bosons following from the experiments on measuring the e⁺ e^- ? W⁺ W^- ? ( e

NO excitation and thermal non-equilibrium within a flat plate boundary layer in an air plasma

Optical emission spectroscopy experiments are carried out by recording the radiation from the γ transitions of nitrogen monoxide in an air inductively coupled plasma in interaction with a water-cooled metallic flat plate at moderate pressure. The calibrated results allow to derive the vibrational and rotational temperatures of the NO(A ² Σ ⁺) excited state as well as its densities in the free jet and within the boundary layer by comparison with calculated spectra. Those results are compared with previous ones concerning temperatures and densities of the ground states of the majority species (N₂, O₂ and NO) that were obtained by laser techniques. As for the NO(X ² Π) ground state, vibration and rotation of the excited state are found out of equilibrium. The NO(A ² Σ ⁺) excited state is found to be populated by an energy transfer from the metastable N₂( A³\varSigma ⁺_uA^{3}\varSigma ^{+}_{u}). The steady state of the plasma allows using this property to derive N₂( A³\varSigma ⁺_uA^{3}\varSigma ^{+}_{u}) densities and N₂ electronic excitation temperatures. Close to the wall, a production of excited NO by a catalytic process is also considered involving N₂( A³\varSigma ⁺_uA^{3}\varSigma ^{+}_{u}) as source of adsorbed atoms. The present results confirm that the kinetic temperature cannot be compared to the rotational temperature derived from optical emission spectroscopy in such plasma conditions.     

Improved sensitivity to charged Higgs searches in top quark decays t→bH+→b(τ+ντ) at the LHC using τ polarisation and multivariate techniques

We present an analysis with improved sensitivity to the light charged Higgs (m_H⁺ < m_t-m_bm_{H^{+}} < m_{t}-m_{b}) searches in the top quark decays t→bH ⁺→b(τ ⁺ ν _τ )+c.c. in the t[`(t)]t\bar{t} and single t/[`(t)]t/\bar{t} production processes at the LHC. In the Minimal Supersymmetric Standard Model (MSSM), one anticipates the branching ratio B (H⁺ ?t⁺n_t) @ 1{\mathcal{B}} (H^{+} \to\tau^{+}\nu_{\tau})\simeq1 over almost the entire allowed tanb\tan\beta range. Noting that the τ ⁺ arising from the decay H ⁺→τ ⁺ ν _τ are predominantly right-polarized, as opposed to the τ ⁺ from the dominant background W ⁺→τ ⁺ ν _τ , which are left-polarized, a number of H ⁺/W ⁺→τ ⁺ ν _τ discriminators have been proposed and studied in the literature. We consider hadronic decays of the τ ^±, concentrating on the dominant one-prong decay channel τ ^±→ρ ^± ν _τ . The energy and p _T of the charged prongs normalised to the corresponding quantities of the ρ ^± are convenient variables which serve as τ ^± polariser. We use the distributions in these variables and several other kinematic quantities to train a boosted decision tree (BDT). Using the BDT classifier, and a variant of it called BDTD, which makes use of decorrelated variables, we have calculated the BDT(D)-response functions to estimate the signal efficiency vs. the rejection of the background. We argue that this chain of analysis has a high sensitivity to light charged Higgs searches up to a mass of 150 GeV in the decays t→bH ⁺ (and charge conjugate) at the LHC. For the case of single top production, we also study the transverse mass of the system determined using Lagrange multipliers.     

Spectroscopy study of air plasma induced by IR CO2 laser pulses

A spectroscopic study of ambient air plasma, initially at room temperature and pressures ranging from 32 to 101 kPa, produced by high-power transverse excitation atmospheric (TEA) CO₂ laser (λ=9.621 and 10.591 μm; τ _FWHM≈64 ns; power densities ranging from 0.29 to 6.31 GW cm⁻²) has been carried out in an attempt to clarify the processes involved in laser-induced breakdown (LIB) air plasma. The strong emission observed in the plasma region is mainly due to electronic relaxation of excited N, O and ionic fragments N⁺. The medium-weak emission is due to excited species O⁺, N²⁺, O²⁺, C, C⁺, C²⁺, H, Ar and molecular band systems of N ₂⁺(_{2}^{+}( B ²\varSigma _u⁺^{2}\varSigma _{\mathrm{u}}^{+} –X ²\varSigma _g⁺)^{2}\varSigma _{\mathrm{g}}^{+}) , N₂(C³ Π _u–B³ Π _g), N ₂⁺(_{2}^{+}( D² Π _g–A² Π _u) and OH(A² Σ ⁺–X² Π). Excitation temperatures of 23400±700 K and 26600±1400 K were estimated by means of N⁺ and O⁺ ionic lines, respectively. Electron number densities of the order of (0.5–2.4)×10¹⁷ cm⁻³ and (0.6–7.5)×10¹⁷ cm⁻³ were deduced from the Stark broadening of several ionic N⁺ and O⁺ lines, respectively. Estimates of vibrational and rotational temperatures of N ₂⁺_{2}^{+} electronically excited species are reported. The characteristics of the spectral emission intensities from different species have been investigated as functions of the air pressure and laser irradiance. Optical breakdown threshold intensities in air at 10.591 μm have been measured.     

Anomalous dipion invariant mass distribution of the ?(4S) decays into ?(1S)π+π? and ?(2S)π+π?

To solve the discrepancy between the experimental data on the partial widths and lineshapes of the dipion emission of ϒ(4S) and the theoretical predictions, we suggest that there is an additional contribution, which had not been taken into account in previous calculations. Noticing that the mass of ϒ(4S) is above the production threshold of B[`(B)]B\bar{B}, the contribution of the sequential process \varUpsilon(4S)? B[`(B)]? \varUpsilon(nS)+S?\varUpsilon(nS)+p⁺p^-\varUpsilon(4S)\to B\bar{B}\to \varUpsilon(nS)+S\to\varUpsilon(nS)+\pi^{+}\pi^{-} (n=1,2) may be sizable, and its interference with that from the direct production would be important. The goal of this work is to investigate if a sum of the two contributions with a relative phase indeed reproduces the data. Our numerical results on the partial widths and the lineshapes d\varGamma(\varUpsilon(4S)?\varUpsilon(2S,1S)p⁺p^-)/d(m_p⁺p^-)d\varGamma(\varUpsilon(4S)\to\varUpsilon(2S,1S)\pi^{+}\pi^{-})/d(m_{\pi ^{+}\pi^{-}}) are satisfactorily consistent with the measurements; thus the role of this mechanism is confirmed. Moreover, with the parameters obtained by fitting the data of the Belle and BaBar collaborations, we predict the distributions dΓ(ϒ(4S)→ϒ(2S,1S)π ⁺ π ⁻)/dcosθ, which have not been measured yet.     

Quenching of the E1 strength in <Superscript>149</Superscript>Nd

Lifetime measurements of excited states in ¹⁴⁹Nd have been performed using the advanced time-delayed b \beta g \gamma g \gamma(t) method. Half-lives of 14 excited states in ¹⁴⁹Nd have been determined for the first time or measured with higher precision. Twelve new g \gamma -lines and 5 new levels have been introduced into the decay scheme of ¹⁴⁹Pr based on results of the g \gamma g \gamma coincidence measurements. Reduced transition probabilities have been determined for 40 g \gamma -transitions in ¹⁴⁹Nd . Configuration assignments for 6 rotational bands in ¹⁴⁹Nd are proposed. Enhanced E1 transitions indicate that the ground-state band and the band built on the 332.9keV level constitute a pair of the K^p = 5/2^±\ensuremath K^{\pi} = 5/2^{\pm} parity doublet bands. Potential energy surfaces on the (b₂,b₃)\ensuremath (\beta_{2},\beta_{3}) -plane have been calculated for the lowest single quasi-particle configurations in ¹⁴⁹Nd using the Strutinski method and the axially deformed Woods-Saxon potential. The predicted occurrence of the octupole-deformed K = 5/2 configuration is in agreement with experiment. Unexpectedly low |D₀|\ensuremath \vert D_0\vert values obtained for the K^p = 5/2^±\ensuremath K^{\pi} = 5/2^{\pm} parity doublet bands may result from cancellation between the proton and neutron shell correction contributions to |D₀|\ensuremath \vert D_0\vert .     

Interference of Higgs boson resonances in $\mu^ + \mu^- \to\tilde{\chi}^0_i\tilde{\chi}^0_j$ with longitudinal beam polarization

We study the interference of resonant Higgs boson exchange in neutralino production in m⁺ m^-\mu^ + \mu^- annihilation with longitudinally polarized beams. We use the energy distribution of the decay lepton in the process [(c)\tilde]⁰_j ? l^± [(l)\tilde]^-±\tilde{\chi}^0_j \to \ell^{\pm} \tilde{\ell}^\mp to determine the polarization of the neutralinos. In the CP-conserving minimal supersymmetric standard model a non-vanishing asymmetry in the lepton energy spectrum is caused by the interference of Higgs boson exchange channels with different CP-eigenvalues. The contribution of this interference is large if the heavy neutral bosons H and A are nearly degenerate. We show that the asymmetry can be used to determine the couplings of the neutral Higgs bosons to the neutralinos. In particular, the asymmetry allows one to determine the relative phase of the couplings. We find large asymmetries and cross sections for a set of reference scenarios with nearly degenerate neutral Higgs bosons.     

Convergence Radii for Eigenvalues of Tri-Diagonal Matrices

Consider a family of infinite tri-diagonal matrices of the form L + zB, where the matrix L is diagonal with entries L _kk  = k ², and the matrix B is off-diagonal, with nonzero entries B _k,k+1 = B _k+1,k  = k ^α , 0 ≤ α < 2. The spectrum of L + zB is discrete. For small |z| the nth eigenvalue E _n (z), E _n (0) = n ², is a well-defined analytic function. Let R _n be the convergence radius of its Taylor’s series about z = 0. It is proved that

π* ←π electronic transition in hydroxy-benzonitriles. I. Orthohydroxybenzonitrile

The longest wavelengthπ* ←π electronic band system of ortho-hydroxybenzonitrile vapour through the absorption technique has been reported for the first time. Assuming a planar molecular geometry in both the electronic states, the molecule is classified into aC _s point group, and the present spectrum is attributed to¹ A′ ←¹ A′ type corresponding to electric dipole forbidden transition¹ B _2u ←¹ A _1g (260 nm band system) of benzene. The most intense band at 33914 cm⁻¹ has been assigned as the 0, 0 band, and the other vibronic bands have been interpreted in terms of the excited state and a few ground state fundamentals.