21 research outputs found
transition form factors in light-cone sum rules
We present a new calculation of the semileptonic tree-level and
flavor-changing neutral current form factors describing -meson transitions
to tensor mesons (). We employ the QCD
Light-Cone Sum Rules approach with -meson distribution amplitudes. We go
beyond the leading-twist accuracy and provide analytically, for the first time,
higher-twist corrections for the two-particle contributions up to twist four
terms. We observe that the impact of higher twist terms to the sum rules is
noticeable. We study the phenomenological implications of our results on the
radiative and semileptonic , decays.Comment: 31 pages, 5 figures, 4 tables, references added, slight modifications
on the text, numerical results revised using a new fit function, main
conclusions unchanged. Version accepted for publication in PR
Towards NNLO accuracy for epsilon '/epsilon
The quantity measures direct CP violation in Kaon
decays. Recent SM predictions show a tension with data, with the
theoretical uncertainty dominating. As rapid progress on the lattice is
bringing nonperturbative long-distance effects under control, a more precise
knowledge of short-distance contributions is needed. We describe the first NNLO
results for and discuss future prospects, as well as
issues of scheme dependence and the separation of perturbative and
nonperturbative effects. Finally we also comment on the solution of the
renormalisation-group evolution in one of the talks at this conference and
present the correct solution.Comment: 8 pages, Proceedings of the Kaon 2016 Conferenc
Recommended from our members
The Belle II physics book
The Belle II detector will provide a major step forward in precision heavy flavor physics, quarkonium and exotic states, searches for dark sectors, and many other areas. The sensitivity to a large number of key observables can be improved by about an order of magnitude compared to the current measurements, and up to two orders in very clean search measurements. This increase in statistical precision arises not only due to the increased luminosity, but also from improved detector efficiency and precision for many channels. Many of the most interesting observables tend to have very small theoretical uncertainties that will therefore not limit the physics reach. This book has presented many new ideas for measurements, both to elucidate the nature of current anomalies seen in flavor, and to search for new phenomena in a plethora of observables that will become accessible with the Belle II dataset. The simulation used for the studiesinthis book was state ofthe artat the time, though weare learning a lot more about the experiment during the commissioning period. The detector is in operation, and working spectacularly well
The Belle II Physics Book
We present the physics program of the Belle II experiment, located on the
intensity frontier SuperKEKB collider. Belle II collected its first
collisions in 2018, and is expected to operate for the next decade. It is
anticipated to collect 50/ab of collision data over its lifetime. This book is
the outcome of a joint effort of Belle II collaborators and theorists through
the Belle II theory interface platform (B2TiP), an effort that commenced in
2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II
program, which includes a wide scope of physics topics: B physics, charm, tau,
quarkonium, electroweak precision measurements and dark sector searches. It is
composed of nine working groups (WGs), which are coordinated by teams of
theorist and experimentalists conveners: Semileptonic and leptonic B decays,
Radiative and Electroweak penguins, phi_1 and phi_2 (time-dependent CP
violation) measurements, phi_3 measurements, Charmless hadronic B decay, Charm,
Quarkonium(like), tau and low-multiplicity processes, new physics and global
fit analyses. This book highlights "golden- and silver-channels", i.e. those
that would have the highest potential impact in the field. Theorists
scrutinised the role of those measurements and estimated the respective
theoretical uncertainties, achievable now as well as prospects for the future.
Experimentalists investigated the expected improvements with the large dataset
expected from Belle II, taking into account improved performance from the
upgraded detector.Comment: 689 page
Diabetik sistopatide sistometri
TEZ151Tez (Uzmanlık) -- Çukurova Üniversitesi, Adana, 1983.Kaynakça (s. [69]-72) var.72 s. : res. ; 31 cm.
Next-to-leading logarithmic QCD contribution of the electromagnetic dipole operator to B̅ →Xsγγ
We calculate the set of O(alpha_s) corrections to the double differential
decay width dGamma_77/(ds_1*ds_2) for the process B -> X_s gamma gamma
originating from diagrams involving the electromagnetic dipole operator O_7.
The kinematical variables s_1 and s_2 are defined as s_i=(p_b - q_i)^2/m_b^2,
where p_b, q_1, q_2 are the momenta of b-quark and two photons. While the
(renormalized) virtual corrections are worked exactly for a certain range of
s_1 and s_2, we retain in the gluon bremsstrahlung process only the leading
power w.r.t. the (normalized) hadronic mass s_3=(p_b-q_1-q_2)^2/m_b^2 in the
underlying triple differential decay width dGamma_77/(ds_1*ds_2*ds_3). The
double differential decay width, based on this approximation is free of
infrared- and collinear singularities when combining virtual- and
bremsstrahlung corrections. The corresponding results are obtained
analytically. When retaining all powers in s_3, the sum of virtual- and
bremstrahlung corrections contains uncanceled 1/epsilon singularities (which
are due to collinear photon emission from the s-quark) and other concepts,
which go beyond perturbation theory, like parton fragmentation functions of a
quark or a gluon into a photon, are needed which is beyond the scope of our
paper.Comment: 22 pages, 6 figure