66 research outputs found
Asymmetry Parameter of the by Analyzing the Transition Form Factors within QCD
Separating the mixture of the and states, the
transition form factors are calculated in
the three-point QCD sum rules approach. The longitudinal, transverse and total
decay widths as well as the asymmetry parameter, characterizing the
polarization of the axial and the branching ratio for these
decays are evaluated.Comment: 25 pages, 3 figures, 3 table
in LEET
Flavour Changing Neutral Current decays of the -meson are a very useful
tool for studying possible physics scenarios beyond the Standard Model (SM),
where of the many FCNC modes radiative, purely leptonic and semi-leptonic
decays of the -meson are relatively clean tests. Within this context the
BELLE collaboration has searched for the process and
provided an upper bound on this decay. In this work we have used this upper
bound in studying the angular coorelations for the related semi-leptonic decay
mode , where we have used the form
factors that have already been estimated for the mode.
Note that the additional form factors that are required were calculated using
the Large Energy Effective Theory (LEET).Comment: 13 pages, 4 figure
Annihilation Contributions in B -> K_1 gamma decay in next-to-leading order in LEET and CP-asymmetry
The effect of weak annihilation and u-quark penguin contribution on the
branching ratio B -> K_1 gamma at next-to-leading order of alpha_s are
calculated using LEET approach. It is shown that the value of LEET form factor
remains the same in the range of unitarity triangle phase alpha favored by the
Standard Model. CP-asymmetry for above mentioned decay has been calculated and
its suppression due to the hard spectator correction has also been
incorporated. In addition, the sensitivity of the CP-asymmetry on the
underlying parameters has been discussed.Comment: 12 pages, 10 figure
Model Independent Analysis of the Forward-Backward Asymmetry for the Decay
The sensitivity of the zero position of the forward backward asymmetry
for the exclusive
decay is examined by using most general non-standard 4-fermion interactions.
Our analysis shows that the zero position of the forward backward asymmetry is
very sensitive to the sign and size of the Wilson coefficients corresponding to
the new vector type interactions, which are the counter partners of the usual
Standard Model operators but have opposite chirality. In addition to these, the
other significant effect comes from the interference of Scalar-Pseudoscalar and
Tensor type operators. These results will not only enhance our theoretical
understanding about the axial vector mesons but will also serve as a good tool
to look for physics beyond the SM.Comment: 14 pages, 8 figures, Published version that appears in EPJ
Rare Decays of \Lambda_b->\Lambda + \gamma and \Lambda_b ->\Lambda + l^{+} l^{-} in the Light-cone Sum Rules
Within the Standard Model, we investigate the weak decays of and with the light-cone
sum rules approach. The higher twist distribution amplitudes of
baryon to the leading conformal spin are included in the sum rules for
transition form factors. Our results indicate that the higher twist
distribution amplitudes almost have no influences on the transition form
factors retaining the heavy quark spin symmetry, while such corrections can
result in significant impacts on the form factors breaking the heavy quark spin
symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of
baryon are also employed in the sum rules for a comparison, which can
give rise to the form factors approximately 5 times larger than that in terms
of conformal expansion. Utilizing the form factors calculated in LCSR, we then
perform a careful study on the decay rate, polarization asymmetry and
forward-backward asymmetry, with respect to the decays of , .Comment: 38 pages, 15 figures, some typos are corrected and more references
are adde
Form factors and branching ratio for the B -> l nu gamma decay
Form factors parameterizing radiative leptonic decays of heavy mesons for photon energy are computed in the language
of dispersion relation. The contributing states to the absorptive part in the
dispersion relation are the multiparticle continum, estimated by quark triangle
graph and resonances with quantum numbers and which includes
and and thier radial excitations, which model the higher
state contributions. Constraints provided by the asymptotic behavior of the
structure dependent amplitude, Ward Identities and gauge invariance are used to
provide useful information for parameters needed. The couplings
and are predicted if we restrict to
first radial excitation; otherwise using these as an input the radiative decay
coupling constants for radial excitations are predicted. The value of the
branching ratio for the process is found to
be in the range . A detailed comparison is given with other
approaches.Comment: 22 pages+two ps figures; Paper has been throughly revised and Sudakov
resummation has been discussed; published versio
Considerations for the Use of Phage Therapy in Clinical Practice
Increasing antimicrobial resistance and medical device-related infections have led to a renewed interest in phage therapy as an alternative or adjunct to conventional antimicrobials. Expanded access and compassionate use cases have risen exponentially but have varied widely in approach, methodology, and clinical situations in which phage therapy might be considered. Large gaps in knowledge contribute to heterogeneity in approach and lack of consensus in many important clinical areas. The Antibacterial Resistance Leadership Group (ARLG) has convened a panel of experts in phage therapy, clinical microbiology, infectious diseases, and pharmacology, who worked with regulatory experts and a funding agency to identify questions based on a clinical framework and divided them into three themes: potential clinical situations in which phage therapy might be considered, laboratory testing, and pharmacokinetic considerations. Suggestions are provided as answers to a series of questions intended to inform clinicians considering experimental phage therapy for patients in their clinical practices
Scientific rationale for Uranus and Neptune <i>in situ</i> explorations
The ice giants Uranus and Neptune are the least understood class of planets in our solar system but the most frequently observed type of exoplanets. Presumed to have a small rocky core, a deep interior comprising ∼70% heavy elements surrounded by a more dilute outer envelope of H2 and He, Uranus and Neptune are fundamentally different from the better-explored gas giants Jupiter and Saturn. Because of the lack of dedicated exploration missions, our knowledge of the composition and atmospheric processes of these distant worlds is primarily derived from remote sensing from Earth-based observatories and space telescopes. As a result, Uranus's and Neptune's physical and atmospheric properties remain poorly constrained and their roles in the evolution of the Solar System not well understood. Exploration of an ice giant system is therefore a high-priority science objective as these systems (including the magnetosphere, satellites, rings, atmosphere, and interior) challenge our understanding of planetary formation and evolution. Here we describe the main scientific goals to be addressed by a future in situ exploration of an ice giant. An atmospheric entry probe targeting the 10-bar level, about 5 scale heights beneath the tropopause, would yield insight into two broad themes: i) the formation history of the ice giants and, in a broader extent, that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. In addition, possible mission concepts and partnerships are presented, and a strawman ice-giant probe payload is described. An ice-giant atmospheric probe could represent a significant ESA contribution to a future NASA ice-giant flagship mission
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