2,847 research outputs found

### Supersymmetric contributions to B --> K \pi branching ratio

We analyze the supersymmetric contributions to the B --> K\pi process. We
show that the simultaneous contributions from the penguin diagrams with
chargino and gluino in the loop could lead to a possible solution to the B -->
K \pi puzzle. Our result indicates that including the stringent constraint from
the b --> s \gamma branching ratio, the supersymmeteric models with light
right-handed top-squark and large mixing between second and third generation of
up and down squarks is the most preferred by the current experimental data.Comment: 4 pages, revtex, 2 figure

### Application of nitroarene dioxygenases in the design of novel strains that degrade chloronitrobenzenes.

Widespread application of chloronitrobenzenes as feedstocks for the production of industrial chemicals and pharmaceuticals has resulted in extensive environmental contamination with these toxic compounds, where they pose significant risks to the health of humans and wildlife. While biotreatment in general is an attractive solution for remediation, its effectiveness is limited with chloronitrobenzenes due to the small number of strains that can effectively mineralize these compounds and their ability to degrade only select isomers. To address this need, we created engineered strains with a novel degradation pathway that reduces the total number of steps required to convert chloronitrobenzenes into compounds of central metabolism. We examined the ability of 2-nitrotoluene 2,3-dioxygenase from Acidovorax sp. strain JS42, nitrobenzene 1,2-dioxygenase (NBDO) from Comamonas sp. strain JS765, as well as active-site mutants of NBDO to generate chlorocatechols from chloronitrobenzenes, and identified the most efficient enzymes. Introduction of the wild-type NBDO and the F293Q variant into Ralstonia sp. strain JS705, a strain carrying the modified ortho pathway for chlorocatechol metabolism, resulted in bacterial strains that were able to sustainably grow on all three chloronitrobenzene isomers without addition of co-substrates or co-inducers. These first-generation engineered strains demonstrate the utility of nitroarene dioxygenases in expanding the metabolic capabilities of bacteria and provide new options for improved biotreatment of chloronitrobenzene-contaminated sites

### B_s^0 - bar{B}_s^0 Mixing and the B_s -> J/psi phi Asymmetry in Supersymmetric Models

We analyse supersymmetric contributions to B_s mixing and their impact on
mixing-induced CP asymmetries, using the mass insertion approximation. We
discuss in particular the correlation of SUSY effects in the CP asymmetries of
B_s -> J/psi phi and B_d -> phi K_S and find that the mass insertions dominant
in B_s mixing and B_d -> phi K_S are (delta_{23}^d)_{LL, RR} and
(delta_{23}^d)_{LR, RL}, respectively. We show that models with dominant
(delta_{23}^d)_{LR, RL} can accomodate a negative value of S_{phi K_S}, in
agreement with the BELLE measurement of that observable, but yield a B_s mixing
phase too small to be observed. On the other hand, models with dominant
(delta_{23}^d)_{LL, RR} predict sizeable SUSY contributions to both Delta M_s
and the mixing phase, but do not allow the asymmetry in B_d -> phi K_S to
become negative, except for small values of the average down squark mass,
which, in turn, entail a value of Delta M_s too large to be observed at the
Tevatron and the LHC. We conclude that the observation of B_s mixing at hadron
machines, together with the confirmation of a negative value of S_{phi K_S},
disfavours models with a single dominant mass insertion.Comment: 17 pages, 5 figure

### Exclusive J/\psi Productions at e^+ e^- Colliders

Exclusive quarkonium pair production in electron-positron collisions is
studied in non-relativistic QCD. The obtained cross section for J/\psi + \eta_c
production in the leading order is confronted against the recent measurements
by the Belle Collaboration at KEKB. It is shown that a large renormalization
K-factor is necessary to explain the experimental data. We point out that the
J^{PC}=0^{-+} nature of the hadronic systems that are assigned to be \eta_c
should be tested by the triple angular distributions in terms of the scattering
angle, and, polar and azimuthal angles of J/\psi into leptons. We further study
J/\psi + J/\psi and \Upsilon + \Upsilon productions at LEP energies. Although
the axial-vector couplings of the Z-boson to charm and bottom quarks allow
production of such pairs when one of them is polarised transversally and the
other longitudinally, we find that the integrated luminosity at Z pole
accumulated by LEP is not large enough to observe the exclusive pair production
of quarkonium.Comment: 11 pages, 2 eps figures, LaTe

### Dispersive evaluation of the second-class amplitude $\tau\to\eta\pi\nu_\tau$ in the standard model

We reevaluate the two form factors relevant for the $\eta\pi$ second-class
$\tau$ decay mode, making systematic use of analyticity, unitarity, combined
with updated inputs to the NLO chiral constraints. We focus, in particular, on
the shape of the $\rho$ resonance peak which is a background-free signature of
a second-class current. Its dispersive construction requires the
$\eta\pi\to\pi\pi$ scattering amplitude which we derive from a family of
Khuri-Treiman equations solutions constrained with accurate recent results on
the $\eta\to3\pi$ Dalitz plot.Comment: Presented at the 12th International workshop on Tau lepton physics
(TAU2012) in Nagoya, Japa

### Angular analysis of B -> J/psi K1 : towards a model independent determination of the photon polarization with B-> K1 gamma

We propose a model independent extraction of the hadronic information needed
to determine the photon polarization of the b-> s gamma process by the method
utilizing the B -> K1 gamma -> K pi pi gamma angular distribution. We show that
exactly the same hadronic information can be obtained by using the B -> J/psi
K1 -> J/psi K pi pi channel, which leads to a much higher precision.Comment: 12 pages, 1 figur

### CP asymmetry and branching ratio of B -> pi pi

We investigate the branching ratios and CP asymmetries of the B -> pi pi
processes measured in B factory experiments. Fits to the experimental data of
this process indicate a large ratio of color-suppressed (C) to color-allowed
(T) tree contributions. We investigate whether the large C/T can be explained
within the QCD based model computation with i) a large effect from the
end-point singularity or with ii) large final-state-interaction phase between
two different isospin amplitudes. We show that the current experimental data do
not exclude either possibility but we may be able to distinguish these two
effects in future measurements of direct CP asymmetry of B -> pi^0 pi^0.Comment: 8 pages, 10 figure

### Anomalous enhancement of a penguin hadronic matrix element in B->K eta'

We estimate the density matrix element for the pi^0, eta and eta' production
from the vacuum in the large-N_c limit. As a consequence, we find that the QCD
axial anomaly leads to highly non-trivial corrections to the usual flavour
SU(3) relations between B^0-> K^0 pi^0, B^0-> K^0 eta and B^0-> K^0 eta' decay
amplitudes. These corrections may explain why the B-> K eta' branching ratio is
about six times larger than the B-> K pi one.Comment: 5 pages, 1 figur

### Charmless B decays

International audienceI discuss charmless B decays and recent puzzles, mainly in B â KÏ, B â ÏÏ, B â KÎ·âČ modes. I will brieïŹy summarize the progresses in the theoretical computations and the proposed solutions to these puzzles

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