Design of Spacecraft Formation Orbits Relative to a Stabilized Trajectory

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76533/1/AIAA-8433-932.pd

Pictorial SU(3)fSU(3)_f approach for two-body Ωc\Omega_c weak decays

We explore two-body non-leptonic weak decays of $\Omega_c^0$ into final states ${\bf B}^{(*)}M$ and ${\bf B}^{(*)}V$, where ${\bf B}^{(*)}$ denotes an octet (a decuplet) baryon, and $M(V)$ represents a pseudoscalar (vector) meson. Based on the $SU(3)$ flavor $[SU(3)_f]$ symmetry, we depict and parameterize the $W$-emission and $W$-exchange processes using the topological diagram approach, establishing strict $SU(3)_f$ relations for possible decay channels. We identify dominant topological parameters, determined by available data, allowing us to explain the experimental ratios ${\cal B}(\Omega_c^0\to\Xi^{*0}\bar K^{*0})/{\cal B}(\Omega_c^0\to\Omega^-\rho^+)=0.28\pm 0.11$, ${\cal B}(\Omega_c^0\to\Xi^-\pi^+)/{\cal B}(\Omega_c^0\to\Xi^{0}\bar K^{0})=0.10\pm 0.02$, and ${\cal B}(\Omega_c^0 \to \Omega^- K^+)/{\cal B}(\Omega_c^0 \to \Omega^- \pi^+)=0.06\pm 0.01$. We also calculate the branching fractions of the Cabibbo-allowed decays, such as ${\cal B}(\Omega_c^0 \to \Xi^{* 0} \bar{K}^{0})=(9.8\pm1.3)\times 10^{-4}$. In particular, we establish approximate isospin relations: ${\cal B}(\Omega_c^0 \to \Xi^{(*)-} \pi^+)\simeq 2{\cal B}(\Omega_c^0 \to \Xi^{(*)0} \pi^0)$ and ${\cal B}(\Omega_c^0 \to \Xi^{(*)-} \rho^+)\simeq 2{\cal B}(\Omega_c^0 \to \Xi^{(*)0} \rho^0)$, where ${\cal B}(\Omega_c^0 \to \Xi^0 \pi^0)=(2.3\pm0.2)\times 10^{-4}$ is accessible to the Belle and LHCb experiments.Comment: 16 pages, 3 tables, 2 figure

Critical behavior of the 3-state Potts model on Sierpinski carpet

We study the critical behavior of the 3-state Potts model, where the spins are located at the centers of the occupied squares of the deterministic Sierpinski carpet. A finite-size scaling analysis is performed from Monte Carlo simulations, for a Hausdorff dimension $d_{f}$ $\simeq 1.8928$. The phase transition is shown to be a second order one. The maxima of the susceptibility of the order parameter follow a power law in a very reliable way, which enables us to calculate the ratio of the exponents $\gamma /\nu$. We find that the scaling corrections affect the behavior of most of the thermodynamical quantities. However, the sequence of intersection points extracted from the Binder's cumulant provides bounds for the critical temperature. We are able to give the bounds for the exponent $1/\nu$ as well as for the ratio of the exponents $\beta/\nu$, which are compatible with the results calculated from the hyperscaling relation.Comment: 13 pages, 4 figure

Coherent-State Approach to Two-dimensional Electron Magnetism

We study in this paper the possible occurrence of orbital magnetim for two-dimensional electrons confined by a harmonic potential in various regimes of temperature and magnetic field. Standard coherent state families are used for calculating symbols of various involved observables like thermodynamical potential, magnetic moment, or spatialdistribution of current. Their expressions are given in a closed form and the resulting Berezin-Lieb inequalities provide a straightforward way to study magnetism in various limit regimes. In particular, we predict a paramagnetic behaviour in the thermodynamical limit as well as in the quasiclassical limit under a weak field. Eventually, we obtain an exact expression for the magnetic moment which yields a full description of the phase diagram of the magnetization.Comment: 21 pages, 6 figures, submitted to PR

Accretion and photodesorption of CO ice as a function of the incident angle of deposition

Non-thermal desorption of inter- and circum-stellar ice mantles on dust grains, in particular ultraviolet photon-induced desorption, has gained importance in recent years. These processes may account for the observed gas phase abundances of molecules like CO toward cold interstellar clouds. Ice mantle growth results from gas molecules impinging on the dust from all directions and incidence angles. Nevertheless, the effect of the incident angle for deposition on ice photo-desorption rate has not been studied. This work explores the impact on the accretion and photodesorption rates of the incidence angle of CO gas molecules with the cold surface during deposition of a CO ice layer. Infrared spectroscopy monitored CO ice upon deposition at different angles, ultraviolet-irradiation, and subsequent warm-up. Vacuum-ultraviolet spectroscopy and a Ni-mesh measured the emission of the ultraviolet lamp. Molecules ejected from the ice to the gas during irradiation or warm-up were characterized by a quadrupole mass spectrometer. The photodesorption rate of CO ice deposited at 11 K and different incident angles was rather stable between 0 and 45$^{\circ}$. A maximum in the CO photodesorption rate appeared around 70$^{\circ}$-incidence deposition angle. The same deposition angle leads to the maximum surface area of water ice. Although this study of the surface area could not be performed for CO ice, the similar angle dependence in the photodesorption and the ice surface area suggests that they are closely related. Further evidence for a dependence of CO ice morphology on deposition angle is provided by thermal desorption of CO ice experiments

Study of B−→Λpˉη(′)B^-\to \Lambda\bar p\eta^{(')} and Bˉs0→ΛΛˉη(′)\bar B^0_s\to \Lambda\bar\Lambda\eta^{(')} decays

We study the three-body baryonic $B\to {\bf B\bar B'}M$ decays with $M$ representing the $\eta$ or $\eta'$ meson. Particularly, we predict that ${\cal B}(B^-\to\Lambda\bar p\eta,\Lambda\bar p\eta')=(5.3\pm 1.4,3.3\pm 0.7)\times 10^{-6}$ or $(4.0\pm 0.7,4.6\pm 1.1)\times 10^{-6}$, where the errors arise from the non-factorizable effects as well as the uncertainties in the $0\to {\bf B\bar B'}$ and $B\to{\bf B\bar B'}$ transition form factors, while the two different results are due to overall relative signs between the form factors, causing the constructive and destructive interference effects. For the corresponding baryonic $\bar B_s^0$ decays, we find that ${\cal B}(\bar B^0_s\to \Lambda\bar \Lambda \eta,\Lambda\bar \Lambda \eta')=(1.2\pm 0.3,2.6\pm 0.8)\times 10^{-6}$ or $(2.1\pm 0.6,1.5\pm 0.4)\times 10^{-6}$ with the errors similar to those above. The decays in question are accessible to the experiments at BELLE and LHCb.Comment: 15 pages, 5 figures, revised version accepted by EPJ