Supersymmetric (SUSY) theories are often thought to give large branching ratios for b → sγ from charged Higgs loops. We show that in many cases chargino loop contributions can cancel those of the Higgs, and SUSY can give B(b → sγ) at or below the Standard Model prediction. We show this occurs because the large stop mass splittings usually found in SUSY break a GIM mechanism suppression. These effects are strongly enhanced by large tan β, so that B(b → sγ) is very sensitive to the value of tan β, contrary to what has been claimed.We also note that the supergravity relation B 0 = A 0 − 1 is somewhat disfavored over the general case.There has been much interest in the decay b → sγ because of new results from the CLEO collaboration which bound the inclusive branching ratio, B(b → sγ), below 5.4 × 10 −4 at the 95% confidence level, and give a non-zero branching ratio for the exclusive decay B → K * γ of about 5 × 10 −5 [1]. One expects this exclusive channel to make up 5% − 40% of the inclusive rate [2], so B(b → sγ) must be greater than about 10 −4 . The Standard Model (SM) contribution depends slowly on the top quark mass and is of order 4 × 10 −4 for m t of 140 GeV. Given this, some recent works [3,4] claim that
By using relations derived from renormalization group equations (RGEs), we find that strong indirect constraints can be placed on the top squark mixing phase in A t from the electric dipole moment of the neutron (d n ). Since m t is large, any GUT-scale phase in A t feeds into other weak scale phases through RGEs, which in turn contribute to d n . Thus CP -violating effects due to a weak-scale A t are strongly constrained. We find that |ImA EW t | must be smaller than or of order |ImB EW |, making the electric dipole moment of the top quark unobservably small in most models. Quantitative estimates of the contributions to d n from A u , A d and B show that substantial fine-tuning is still required to satisfy the experimental bound on d n . While the low energy phases of the A's are not as strongly constrained as the phase of B EW , we note that the phase of a universal A GU T induces large contributions in the phase of B EW through RGEs, and is thus still strongly constrained in most models with squark masses below a TeV.
The transverse polarization of the muon (Pk) in the decay Kt+.nOpCv, is a very useful tool for studying CP violation because a detectable nonzero Pb can only arise from physics beyond the standard model. Further, P; is interesting because it probes a different region of parameter space than many other CP-violating observables. To help justify an experimental search, we present three models which give PA 2 lop3 and which are not contradicted by other experimental data. We also comment on K-.npp decays.
We study the T -violating lepton transverse polarization (P ⊥ l ) in three body semileptonic heavy meson decays to pseudoscalar mesons and to vector mesons. We calculate these polarizations in the heavy quark effective limit, which simplifies the expressions considerably. After examining constraints from CP conserving (including b → sγ) and CP violating processes, we find that in B decays, P ⊥ of the muon in multi-Higgs doublet models can be of order 10%, while P ⊥ of the τ can even approach unity. In contrast, P ⊥ µ in D decays is at most 1.5%. We discuss possibilities for detection of P ⊥ l at current and future B factories. We also show that P ⊥ l in decays to vector mesons, unlike in decays to pseudoscalars, can get contributions from left-right models. Unfortunately, P ⊥ l in that case is proportional to W L -W R mixing, and is thus small.
We define a new measurement of entanglement, the entanglement of projection, and find that it is natural to write the entanglements of formation and assistance in terms of it. Our measure allows us to describe a new class of quantum erasers which restore entanglement rather than just interference.Such erasers can be implemented with simple quantum computer components.We propose realistic optical versions of these erasers. PACS: 03.65. Bz,03.67.Lx Entanglement is the degree to which the wave function does not factorize. For example, an S = 0 two particle system |+− −|−+ is maximally entangled: measurement of the spins reveals they are completely anticorrelated. The concept of entanglement goes to the very heart of quantum mechanics, and understanding its nature is a prerequisite to understanding quantum mechanics itself. Two-particle entanglement was used by Einstein, Podolsky and Rosen [1] to argue that quantum mechanics could not be a complete description of realitythat there had to be an underlying local theory. But J. S. Bell used such entangled states to show that any local underlying theory would have to satisfy certain inequalities, which quantum mechanics explicitly violates [2]. Experiments on such entangled states have shown 1
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