Supermembrane limit of Yang-Mills theory

We consider Yang-Mills theory with $N{=}1$ super translation group in eleven auxiliary dimensions as the structure group. The gauge theory is defined on a direct product manifold $\Sigma_3\times S^1$, where $\Sigma_3$ is a three-dimensional Lorentzian manifold and $S^1$ is a circle. We show that in the infrared limit, when the metric on $S^1$ is scaled down, the Yang-Mills action supplemented by a Wess-Zumino-type term reduces to the action of an M2-brane.Comment: 1+6 page

Phenomenological Applications of QCD Factorization to Semi-inclusive B Decays

We have systematically investigated the semi-inclusive B decays $B\to MX$, which are manifestations of the quark decay $b \to Mq$, within a framework inspired by QCD-improved factorization. These decays are theoretically clean and have distinctive experimental signatures. We focus on a class of these that do not require any form factor information and therefore may be especially suitable for extracting information on the angles $\alpha$ and $\gamma$ of the unitarity triangle. The strong phase coming from final-state rescattering due to hard gluon exchange between the final states can induce large rate asymmetries for tree-dominated color-suppressed modes $(\pi^0,\rho^0,\omega)X_{\bar s}$. The nonfactorizable hard spectator interactions in the 3-body decay $B\to Mq_1\bar q_2$, though phase-space suppressed, are extremely important for the tree-dominated modes $(\pi^0,\rho^0,\omega)X_{\bar s},~\phi X$, $J X_s,J X$ and the penguin-dominated mode $\omega X_{s\bar s}$. Our result for ${\cal B}(B\to J X_s)$ is in agreement with experiment. $B^0_s\to (\pi^0,\rho^0,\omega)X_{\bar s}$, $\rho^0X_{s\bar s}$, $B^0\to(K^-X,K^{*-}X)$ and $B^-\to (K^0X_s,K^{*0}X_s)$ are the most promising ones in searching for direct CP violation: they have branching ratios of order $10^{-6}-10^{-4}$ and CP rate asymmetries of order $(10-40)$.Comment: 12 pages, talk given at International Conference on Flavor Physics, Zhang-Jia-Jie City, Hunan, China, 31 May - 6 June, 200

PENGEMBANGAN DAN ANALISA KESERAGAMAN ALIRAN TEROWONGAN ANGIN TIPE TERBUKA SEBAGAI SARANA PENGUJIAN AERODINAMIKA

Terowongan angin sebagai sarana praktikum dan riset di bidang aerodinamika sangat penting keberadaannya, namun harganya yang mahal seringkali menjadi kendala utama di berbagai institusi pendidikan. Pengembangan terowongan angin dengan biaya murah namun memenuhi syarat sangat penting untuk dilakukan. Penelitian ini bertujuan untuk mengembangkan terowongan angin tipe terbuka dan menguji keseragaman aliran pada seksi uji sehingga layak untuk dipergunakan. Terowongan angin dibuat dari plat besi dengan tebal 1,4 mm, angin dihasilkan oleh fan aksial yang digerakkan dengan motor listrik dengan daya 1 HP. Pengujian dilakukan pada bebrapa kecepatan angin yang berbeda, variasi kecepatan diperoleh dengan mengubah putaran motor listrik menggunakan inverter. Hasil pengujian menunjukkan bahwa kecepatan terendah yang dicapai adalah 2 m/s dan tertinggi 5,8 m/s. Pada kecepatan 2 m/s variasi kecepatan pada seksi uji sekitar 0,1 m/s , dan pada kecepatan 5,8 m/s sekitar 0,1 hingga 0,3 m/s Kata Kunci : terowongan angin, aerodinamika, open circuit wind tunne

Maximally Non-Abelian Vortices from Self-dual Yang--Mills Fields

A particular dimensional reduction of SU(2N) Yang--Mills theory on $\Sigma \times S^2$, with $\Sigma$ a Riemann surface, yields an $S(U(N) \times U(N))$ gauge theory on $\Sigma$, with a matrix Higgs field. The SU(2N) self-dual Yang--Mills equations reduce to Bogomolny equations for vortices on $\Sigma$. These equations are formally integrable if $\Sigma$ is the hyperbolic plane, and we present a subclass of solutions.Comment: 11 page

New Physics in b --> s bar(s) s Decay

We perform a model-independent analysis of the data on branching ratios and CP asymmetries of $B\to\phi K$ and $B\to\eta^{(')} K^{(*)}$ modes. The present data is encouraging to look for indirect evidences of physics beyond the Standard Model. We investigate the parameter spaces for different possible Lorentz structures of the new physics four-Fermi interaction. It is shown that if one takes the data at $1\sigma$ confidence level, only one particular Lorentz structure is allowed. Possible consequences for the $B_s$ system are also discussed.Comment: 9 pages, 3 encapsulated figures, minor changes in the text, conclusions unchanged, a few references added, version to appear in PL

Yang-Yang thermodynamics on an atom chip

We investigate the behavior of a weakly interacting nearly one-dimensional (1D) trapped Bose gas at finite temperature. We perform in situ measurements of spatial density profiles and show that they are very well described by a model based on exact solutions obtained using the Yang-Yang thermodynamic formalism, in a regime where other, approximate theoretical approaches fail. We use Bose-gas focusing [Shvarchuck etal., Phys. Rev. Lett. 89, 270404 (2002)] to probe the axial momentum distribution of the gas, and find good agreement with the in situ results.Comment: extended introduction and conclusions, and minor changes throughout; accepted for publication in Phys. Rev. Let