Modulational instability criteria for two-component Bose-Einstein condensates

The stability of colliding Bose-Einstein condensates is investigated. A set of coupled Gross-Pitaevskii equations is thus considered, and analyzed via a perturbative approach. No assumption is made on the signs (or magnitudes) of the relevant parameters like the scattering lengths and the coupling coefficients. The formalism is therefore valid for asymmetric as well as symmetric coupled condensate wave states. A new set of explicit criteria is derived and analyzed. An extended instability region, in addition to an enhanced instability growth rate is predicted for unstable two component bosons, as compared to the individual (uncoupled) state.Comment: 4 pages, 1 figur

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PEMANFAATAN ALAT PERAGA RANGKA TUBUH UNTUK MENINGKATKAN KEMAMPUAN COMPREHENSION SISWA PADA KONSEP SISTEM GERAK MANUSIA

“Pemanfaatan Alat Peraga Rangka Tubuh untuk Meningkatkan Kemampuan Comprehension Siswa pada Konsep Sistem Gerak Manusia”, Pembimbing 1 Prof. Dr. H. Toto Sutarto Gani Utari, M.Pd ., dan Pembimbing 2 Dr. H. Uus Toharudin, M.Pd . Tujuan penelitian ini adalah untuk mengetahui apakah ada peningkatan comprehension (pemahaman) kelas XI dengan memanfaatkan alat peraga rangka tubuh pada konsep sistem gerak manusia. Penelitian ini menggunakan metode Pre - Experimental Designs , di mana tidak ada penelitian variabel kontrol dan sampel tidak dipilih secara random. Populasi dari penelitian ini adalah siswa kelas XI SMA Pasundan 2 Cimahi, yaitu kelas XI IPA 2 yang berjumlah 30 orang. I nstrumen penelitian ini berupa tes pengetahuan dengan soal - soal pilihan ganda berjumlah 3 6 soal. Tes terdiri dua tahapan yaitu pre test dan posttest . Dari hasil penelitian di dapatkan nilai rata – rata pretest 39. 6 7 dan rata – rata posttest sebesar 78.33 . Setelah di lakukan penelitian pretest dan posttest peneliti melanjutkan dengan uji t dan di peroleh dengan hasil uji t signifikan karena di da patkan hasi hitung t hit > t tab = > 2.66. sehingga dapat di simpulkan bahwa “Pemanfaatan Alat Peraga Rangka Tubuh untuk Meningkatkan Kemampuan Comprehension Siswa pada Konsep Sistem Gerak Manusia” dapat meningkatkan kemampuan comprehension (pemahaman ). Kata Kunci : Alat peraga rangka tubuh, kemampuan comprehension (pemahaman), sistem gerak manusia

The Lorentz and CPT violating effects on the Z\to l^+ l^- decay

We study the Lorentz and CPT violating effects on the branching ratio BR, the CPT violating asymmetry A_{CPT} and the ratio of the decay width, including only the Lorentz violating effects, to the one obtained in the standard model, for the flavor dependent part of the lepton flavor conserving Z\to l^+ l^- (l=e,\mu,\tau) decay. The inclusion of the Lorentz and CPT violating effects to the standard model contribution is too small to be detected, since the corresponding coefficients are highly suppressed at the low energy scale.Comment: 11 pages, 6 figure

Creating Ioffe-Pritchard micro-traps from permanent magnetic film with in-plane magnetization

We present designs for Ioffe-Pritchard type magnetic traps using planar patterns of hard magnetic material. Two samples with different pattern designs were produced by spark erosion of 40 $\mu$m thick FePt foil. The pattern on the first sample yields calculated axial and radial trap frequencies of 51 Hz and 6.8 kHz, respectively. For the second sample the calculated frequencies are 34 Hz and 11 kHz. The structures were used successfully as a magneto-optical trap for $^{87}$Rb and loaded as a magnetic trap. A third design, based on lithographically patterned 250 nm thick FePt film on a Si substrate, yields an array of 19 traps with calculated axial and radial trap frequencies of 1.5 kHz and 110 kHz, respectively.Comment: 8 pages, 5 figures Revised and accepted for EPJD, improved picture

Nucleon form factors, B-meson factories and the radiative return

The feasibility of a measurement of the electric and magnetic nucleon form factors at $B$-meson factories through the radiative return is studied. Angular distributions allow a separation of the contributions from the two form factors. The distributions are presented for the laboratory and the hadronic rest frame, and the advantages of different coordinate systems are investigated. It is demonstrated that $Q^2$ values up to 8 or even 9 GeV$^2$ are within reach. The Monte Carlo event generator PHOKHARA is extended to nucleon final states, and results are presented which include Next-to-Leading Order radiative corrections from initial-state radiation. The impact of angular cuts on rates and distributions is investigated and the relative importance of radiative corrections is analysed.Comment: 9 pages, 11 figures. Final version to appear in Eur. Phys. J.

A description of the ratio between electric and magnetic proton form factors by using space-like, time-like data and dispersion relations

We use the available information on the ratio between the electric and magnetic proton form factors coming from recently published space-like data and from the few available time-like data. We apply a dispersive procedure on these data to evaluate the behaviour of this ratio, as a complex function, for all values of q^2.Comment: 12 pages, 7 Encapsulated Postscript figures, uses epsfig, rotating, exscale, amsmath, cite, latexsym, graphics, color packages, added reference

Zemach and magnetic radius of the proton from the hyperfine splitting in hydrogen

The current status of the determination of corrections to the hyperfine splitting of the ground state in hydrogen is considered. Improved calculations are provided taking into account the most recent value for the proton charge radius. Comparing experimental data with predictions for the hyperfine splitting, the Zemach radius of the proton is deduced to be $1.045(16)$ fm. Employing exponential parametrizations for the electromagnetic form factors we determine the magnetic radius of the proton to be $0.778(29)$ fm. Both values are compared with the corresponding ones derived from the data obtained in electron-proton scattering experiments and the data extracted from a rescaled difference between the hyperfine splittings in hydrogen and muonium

Anisotropic field dependence of the magnetic transition in Cu2Te2O5Br2

We present the results of measurements of the thermal conductivity of Cu2Te2O5Br2, a compound where tetrahedra of Cu^{2+} ions carrying S=1/2 spins form chains along the c-axis of the tetragonal crystal structure. The thermal conductivity kappa was measured along both the c- and the a-direction as a function of temperature between 3 and 300 K and in external magnetic fields H up to 69 kOe, oriented both parallel and perpendicular to the c-axis. Distinct features of kappa(T) were observed in the vicinity of T_N=11.4 K in zero magnetic field. These features are unaltered in external fields which are parallel to the c-axis, but are more pronounced when a field is applied perpendicularly to the c-axis. The transition temperature increases upon enhancing the external field, but only if the field is oriented along the a-axis.Comment: 5 pages, 3 figure