Global shallow water magnetohydrodynamic waves in the solar tachocline

We derive analytical solutions and dispersion relations of global magnetic Poincar\'e (magneto-gravity) and magnetic Rossby waves in the approximation of shallow water magnetohydrodynamics. The solutions are obtained in a rotating spherical coordinate system for strongly and weakly stable stratification separately in the presence of toroidal magnetic field. In both cases magnetic Rossby waves split into fast and slow magnetic Rossby modes. In the case of strongly stable stratification (valid in the radiative part of the tachocline) all waves are slightly affected by the layer thickness and the toroidal magnetic field, while in the case of weakly stable stratification (valid in the upper overshoot layer of the tachocline) magnetic Poincar\'e and fast magnetic Rossby waves are found to be concentrated near the solar equator, leading to equatorially trapped waves. However, slow magnetic Rossby waves tend to concentrate near the poles, leading to polar trapped waves. The frequencies of all waves are smaller in the upper weakly stable stratification region than in the lower strongly stable stratification one

Keeping visual-auditory associations in mind: The impact of detail and meaningfulness on crossmodal working memory load

Complex objects have been found to take up more visual working memory---as measured by lowered change-detection accuracy with such stimuli---than simple colored shapes (Treisman, 2006; Xu, 2002). While verbal working memory studies have similarly shown reduced apparent capacity for longer words (Baddeley, 2007), other research has demonstrated that features contributing to object categorization and recognizability can help visual working memory capacity (Olsson & Poom, 2005; Alvarez & Cavanagh, 2004). Until very recently, no measures of crossmodal working memory capacity had been proposed, even though crossmodal associations are part of the fabric of learning, from classical conditioning to calculus. The working memory load of a range of complex crossmodal (visual--auditory) objects was measured here in a sequence of experiments adapting classic visual change detection procedures (Vogel et al., 2001). The adapted method involves rapid sequential presentation of objects, each comprising a sound and an image, with a test object appearing after a 1-second delay. Application of this method shed light on the working memory impact of two sources of complexity, featural detail and object meaningfulness. Displaying the test object in a previously unused location---in this case, the center of the screen---resulted in lower change-detection performance compared to placement in its original location. Test location interacted with the role of different image types (gray and colored shapes, drawings, and photos). Image type showed no consistent pattern of influence on working memory capacity when test objects appeared in their original locations; when shown in an alternate location, crossmodal associations involving more-detailed images were more accurately recalled. Independent of test location, more-complex animal sounds provided better crossmodal change detection performance than abstract tones. An association measure showed consistently higher numbers of associations for representational images than abstract ones. Observers\u27 response bias was lower for meaningful images, but their change-detection accuracy did not differ by image meaningfulness. The results obtained with this novel crossmodal working memory measure demonstrate that perceptual detail contributes to effective crossmodal working memory capacity for sounds and for abstract and realistic images

The Schwinger Nonet Mass and Sakurai Mass-Mixing Angle Formulae Reexamined

We study the origins of the inaccuracies of Schwinger's nonet mass, and the Sakurai mass-mixing angle, formulae for the pseudoscalar meson nonet, and suggest new versions of them, modified by the inclusion of the pseudoscalar decay constants. We use these new formulae to determine the pseudoscalar decay constants and mixing angle. The results obtained, f_8/f_\pi =1.185\pm 0.040, f_9/f_\pi =1.095\pm 0.020, f_\eta /f_\pi =1.085\pm 0.025, f_{\eta ^{'}}/f_\pi =1.195\pm 0.035, \theta =(-21.4\pm 1.0)^o, are in excellent agreement with experiment.Comment: 17 pages, LaTe

Numerical Calculation of Convection with Reduced Speed of Sound Technique

Context. The anelastic approximation is often adopted in numerical calculation with low Mach number, such as stellar internal convection. This approximation requires frequent global communication, because of an elliptic partial differential equation. Frequent global communication is negative factor for the parallel computing with a large number of CPUs. Aims. The main purpose of this paper is to test the validity of a method that artificially reduces the speed of sound for the compressible fluid equations in the context of stellar internal convection. The reduction of speed of sound allows for larger time steps in spite of low Mach number, while the numerical scheme remains fully explicit and the mathematical system is hyperbolic and thus does not require frequent global communication. Methods. Two and three dimensional compressible hydrodynamic equations are solved numerically. Some statistical quantities of solutions computed with different effective Mach numbers (due to reduction of speed of sound) are compared to test the validity of our approach. Results. Numerical simulations with artificially reduced speed of sound are a valid approach as long as the effective Mach number (based on the reduced speed of sound) remains less than 0.7.Comment: 16 pages, 10 figures, accepted to A&

On The Dimensional Methods in Rare b Decays

Since several years there exists a question whether the dimensional reduction and the usual dimensional regularization give different results for the QCD-improved $b \rightarrow s \gamma$ and $b \rightarrow s$ $gluon$ decay rates. Here it is demonstrated explicitly that this is not the case: As long as physically meaningful quantities are considered, the results obtained with help of both techniques agree.Comment: 14 pages (including 1 page figures

Comment on studying the corrections to factorization in B -> D(*) X

We propose studying the mechanism of factorization in exclusive decays of the form B->D(*)X by examining the differential decay rate as a function of the invariant mass of the light hadronic state X. If factorization works primarily due to the large N_c limit then its accuracy is not expected to decrease as the X invariant mass increases. However, if factorization is mostly a consequence of perturbative QCD then the corrections should grow with the X invariant mass. Combining data for hadronic tau decays and semileptonic B decays allows tests of factorization to be made for a variety of final states. We discuss the examples of B->D^*\pi^+\pi^-\pi^-\pi^0 and B->D^*\omega\pi^-. The mode B->D^*\omega\pi^- will allow a precision study of the dependence of the corrections to factorization on the invariant mass of the light hadronic state.Comment: 7 pages, minor clarifications to tex

η−η′\eta-\eta^\prime mixing and the next-to-leading-order power correction

The next-to-leading-order $O(1/Q^4)$ power correction for $\eta\gamma$ and $\eta^\prime\gamma$ form factors are evaluated and employed to explore the $\eta-\eta^\prime$ mixing. The parameters of the two mixing angle scheme are extracted from the data for form factors, two photon decay widths and radiative $J/\psi$ decays. The $\chi^2$ analysis gives the result: $f_{\eta_1}=(1.16\pm0.06)f_\pi, f_{\eta_8}=(1.33\pm0.23)f_\pi, \theta_1=-9^\circ\pm 3^\circ, \theta_8=-21.3^\circ\pm 2.3^\circ$, where $f_{\eta_{1(8)}}$ and $\theta_{1(8)}$ are the decay constants and the mixing angles for the singlet (octet) state. In addition, we arrive at a stringent range for $f_{\eta^\prime}^c:-10$ MeV$\le f_{\eta^\prime}^c\le -4$ MeV.Comment: 23 pages, 9 figures, To be publshied in Phys. Rev.

The speaking vocabulary of kindergarten, grade I, grade II, and grade III

Thesis (Ed.M.)--Boston Universit

Flavor Changing Neutral Currents in a Realistic Composite Technicolor Model

We consider the phenomenology of a composite technicolor model proposed recently by Georgi. Composite technicolor interactions produce four-quark operators in the low energy theory that contribute to flavor changing neutral current processes. While we expect operators of this type to be induced at the compositeness scale by the flavor-symmetry breaking effects of the preon mass matrices, the Georgi model also includes operators from higher scales that are not GIM-suppressed. Since these operators are potentially large, we study their impact on flavor changing neutral currents and CP violation in the neutral $B$, $D$, and $K$ meson systems.Comment: 16 pages, LaTeX + embedded PicTeX figures requiring prepictex, pictex, and postpictex inputs. HUTP.STY include

Resonant behaviour in double charge exchange reaction of \pi^+ mesons on the nuclear photoemulsion

The invariant mass spectra of the $pp\pi^-$ and $pp$ systems produced in the double charge exchange (DCX) of positively charged pions on photoemulsion are analysed. A pronounced peak is observed in the $pp\pi^-$ invariant mass spectrum, while the $M_{pp}$ spectrum exhibits a strong Migdal-Watson effect of the proton-proton final state interaction. These findings are in favor of the $NN$-decoupled $NN\pi$ pseudoscalar resonance with T=0 called $d'$.Comment: 13 pages, 5 figures, revised versio