10,129 research outputs found
Penguin Mediated B Decays at BABAR
We report on preliminary results of searches for penguin mediated B decays
based on 20.7 fb^{-1} of data collected at the Y(4S) peak with the BABAR
detector at PEP-II. The following branching fractions have been measured: BR(B+
--> phi K+) = (7.7^{+1.6}_{-1.4} +- 0.8)*10^{-6}, BR(B0 --> phi K0) =
(8.1^{+3.1}_{-2.5} +- 0.8)*10^{-6}, BR(B+ --> phi K*+) = (9.7^{+4.2}_{-3.4} +-
1.7)*10^{-6}, BR(B0 --> phi K*0) = (8.7^{+2.5}_{-2.1} +- 1.1)*10^{-6}, BR(B+-->
omega pi+) = (6.6^{+2.1}_{-1.8} +- 0.7)*10^{-6}, BR(B --> eta K^*0) =
(19.8^{+6.5}_{-5.6} +-1.7)*10^{-6}, where the first error is statistical and
the second systematic. For several other modes we report upper limits on their
branching fractions; for example for the following flavor-changing neutral
current decays, BR(B--> K l+ l-) K* l+ l-) <
2.5*10^{-6}, at 90% Confidence Level (C.L.).Comment: 9 pages, 6 postscript figues, presented at EPS200
Rare Decays With LHCb
Rare decays involving leptons or photons in the final states are studied
using 1.0 fb^{-1} of pp collisions at a centre-of-mass energy of sqrt{s}=7TeV
collected by the LHCb experiment in 2011. We present results of measurements of
branching ratios, angular distributions, and isospin asymmetries obtained using
this data sample.Comment: 6 pages, 3 figures, Proceedings of Rencontres du Vietnam, Beyond The
Standard Model of Particle Physics, Qui Nhon, Vietnam July 15-21, 201
Measurements of B- -> D(*)0 K(*)- Decays Related to gamma
We present measurements of branching fractions and CP asymmetries of several
B- -> D(*)0 K(*)- decays, with the D(*)0 decaying to CP-even, CP-odd, and
flavor eigenstates, that can constrain the CP angle gamma as well as the
amplitude ratio rb=A(B -> u)/A(B -> c), using methods proposed by Gronau,
London and Wyler or Atwood, Dunietz and Sony. We use data collected with the
BABAR detector at the PEP-II asymmetric energy e+e- collider at SLAC.Comment: 6 pages, 9 postscript figures, presented at DPF200
Search for New Physics with Rare Heavy Flavour Decays at LHCb
The LHCb experiment has the potential, during the 2010-11 run, to observe the
rare decay or improve significantly its exclusion limits.
This study will provide very sensitive probes of New Physics (NP) effects. High
sensitivity to NP contributions is also achieved by measuring photon
polarization by performing a time dependent analysis of ,
and by an angular study of the decay . Preparations
for these analyses are presented and studies shown of how existing data, for
example prompt events, can be used to validate the analysis strategy.Comment: 5 pages, 6 figures, presented at ICHEP conference, Paris 201
Body size-related constraints on the movement behaviour of the arctic notostracan Lepidurus arcticus (Pallas, 1973) under laboratory conditions
The movement behaviour of individuals has long been acknowledged as a key determinant of species distribution in space and time. Information on benthic macroinvertebrates from aquatic habitats are still scant, however, and for polar species are virtually nonexistent. Here, the influence of body size on the movement behaviour of the arctic notostracan Lepidurus arcticus (Pallas) was examined under resource-free laboratory conditions. The mean step length, total path length and average speed were determined for specimens varying in body dry mass by six orders of magnitude. The scale-independent fractal dimension D was used to quantify movement path tortuosity. Among the different movement metrics considered, the body size of specimens scaled significantly only with path tortuosity; specifically, a negative relationship with a breakpoint was observed between individual body masses and the D values of the respective movement paths. The results are discussed considering similar results obtained for benthic crustaceans from temperate habitats. Additionally, their implications for future investigations explicitly considering temperature effects on movement behaviour are briefly considere
Asymptotic scaling in a model class of anomalous reaction-diffusion equations
We analyze asymptotic scaling properties of a model class of anomalous
reaction-diffusion (ARD) equations. Numerical experiments show that solutions
to these have, for large , well defined scaling properties. We suggest a
general framework to analyze asymptotic symmetry properties; this provides an
analytical explanation of the observed asymptotic scaling properties for the
considered ARD equations.Comment: To appear in J. Nonlin. Math. Phy
Asymptotic scaling symmetries for nonlinear PDEs
In some cases, solutions to nonlinear PDEs happen to be asymptotically (for
large and/or ) invariant under a group which is not a symmetry of
the equation. After recalling the geometrical meaning of symmetries of
differential equations -- and solution-preserving maps -- we provide a precise
definition of asymptotic symmetries of PDEs; we deal in particular, for ease of
discussion and physical relevance, with scaling and translation symmetries of
scalar equations. We apply the general discussion to a class of
``Richardson-like'' anomalous diffusion and reaction-diffusion equations, whose
solution are known by numerical experiments to be asymptotically scale
invariant; we obtain an analytical explanation of the numerically observed
asymptotic scaling properties. We also apply our method to a different class of
anomalous diffusion equations, relevant in optical lattices. The methods
developed here can be applied to more general equations, as clear by their
geometrical construction
The nitrogen cycle on Mars
Nirtogen is an essential element for the evolution of life, because it is found in a variety of biologically important molecules. Therefore, N is an important element to study from a exobiological perspective. In particular, fixed nitrogen is the biologically useful form of nitrogen. Fixed nitrogen is generally defines as NH3, NH4(+), NO(x), or N that is chemically bound to either inorganic or organic molecules, and releasable by hydrolysis to NH3 or NH4(+). On Earth, the vast majority of nitrogen exists as N2 in the atmosphere, and not in the fixes form. On early Mars the same situations probably existed. The partial pressure of N2 on early Mars was thought to be 18 mb, significantly less than that of Earth. Dinitrogen can be fixed abiotically by several mechanisms. These mechanisms include thernal shock from meteoritic infall and lightning, as well as the interaction of light and sand containing TiO2 which produces NH3 that would be rapidly destroyed by photolysis and reaction with OH radicals. These mechanisms could have been operative on primitive Mars.The chemical processes effecting these compounds and possible ways of fixing or burying N in the Martian environment are described. Data gathered in this laboratory suggest that the low abundance of nitrogen along (compared to primitive Earth) may not significantly deter the origin and early evolution of a nitrogen utilizing organisms. However, the conditions on current Mars with respect to nitrogen are quite different, and organisms may not be able to utilize all of the available nitrogen
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