2,213 research outputs found
Kaon decays and the flavour problem
After a brief introduction to the so-called flavour problem, we discuss the
role of rare K decays in probing the mechanism of quark-flavour mixing.
Particular attention is devoted to the formulation of the Minimal Flavour
Violation hypothesis, as a general and natural solution to the flavour problem,
and to the fundamental role of K -> pi nu nu-bar decays in testing this
scenario.Comment: 10 pages, 6 figures, contribution to TH 2002 (Paris, July 2002
Long-distance contribution to the forward-backward asymmetry in decays K+ --> pi+ l+ l-
The long-distance contribution via the two-photon intermediate state to the
forward-backward asymmetries in decays K+ --> pi+ l+ l- (l=e and mu) has been
studied within the standard model. In order to evaluate the dispersive part of
the K+ --> pi+ gamma* gamma* --> pi+ l+ l- amplitude, we employ a
phenomenological form factor to soften the ultraviolet behavior of the
transition. It is found that, this long-distance transition, although subject
to some theoretical uncertainties, can lead to significant contributions to the
forward-backward asymmetries, which could be tested in the future high-precise
experiments.Comment: 13 pages, 5 figure
K^+ -> pi^+pi^0e^+e^-: a novel short-distance probe
We study the decay K^+ -> pi^+ pi^0 e^+ e^-, currently under analysis by the
NA62 Collaboration at CERN. In particular, we provide a detailed analysis of
the Dalitz plot for the long-distance, gamma^*-mediated, contributions
(Bremsstrahlung, direct emission and its interference). We also examine a set
of asymmetries to isolate genuine short-distance effects. While we show that
charge asymmetries are not required to test short distances, they provide the
best environment for its detection. This constitutes by itself a strong
motivation for NA62 to study K^- decays in the future. We therefore provide a
detailed study of different charge asymmetries and the corresponding estimated
signals. Whenever possible, we make contact with the related processes K^+ ->
pi^+ pi^0 gamma and K_L -> pi^+ pi^- e^+ e^- and discuss the advantages of K^+
-> pi^+ pi^0 e^+ e^- over them.Comment: 25 pages, 6 figure
Experimental observation of impossible-to-beat quantum advantage on a hybrid photonic system
Quantum resources outperform classical ones for certain communication and
computational tasks. Remarkably, in some cases, the quantum advantage cannot be
improved using hypothetical postquantum resources. A class of tasks with this
property can be singled out using graph theory. Here we report the experimental
observation of an impossible-to-beat quantum advantage on a four-dimensional
quantum system defined by the polarization and orbital angular momentum of a
single photon. The results show pristine evidence of the quantum advantage and
are compatible with the maximum advantage allowed using postquantum resources.Comment: REVTeX4, 5 pages, 2 figure
Production of Succinic Acid From Basfia succiniciproducens
Basfia succiniciproducens is a facultative anaerobic capnophilic bacterium, isolated
from rumen, that naturally produces high amounts of succinic acid by fixing CO2 and
using fumarate as final electron acceptor. This metabolic feature makes it one of the
ideal candidates for developing biotechnological industrial routes that could
eventually replace the polluting and environment unfriendly petrochemical ones
that are still main sources for the production of this value-added compound. In
fact, due to the large number of applications of succinic acid that range from the more
traditional ones as food additive or pharmaceutical intermediate to the most recent as
building block for biopolymers and bioplastic, increasing demand and market size growth
are expected in the next years. In line with a âgreen revolutionâ needed to preserve our
environment, the great challenge is the establishment of commercially viable production
processes that exploit renewable materials and in particular preferably non-food
lignocellulosic biomasses and waste products. In this review, we describe the currently
available literature concerning B. succiniciproducens since the strain was first isolated,
focusing on the different renewable materials and fermentation strategies used to improve
succinic acid production titers to date. Moreover, an insight into the metabolic engineering
approaches and the key physiological characteristics of B. succiniciproducens deduced
from the different studies are presented
Flavor Alignment via Shining in RS
We present a class of warped extra dimensional models whose flavor violating
interactions are much suppressed compared to the usual anarchic case due to
flavor alignment. Such suppression can be achieved in models where part of the
global flavor symmetry is gauged in the bulk and broken in a controlled manner.
We show that the bulk masses can be aligned with the down type Yukawa couplings
by an appropriate choice of bulk flavon field representations and TeV brane
dynamics. This alignment could reduce the flavor violating effects to levels
which allow for a Kaluza-Klein scale as low as 2-3 TeV, making the model
observable at the LHC. However, the up-type Yukawa couplings on the IR brane,
which are bounded from below by recent bounds on CP violation in the D system,
induce flavor misalignment radiatively. Off-diagonal down-type Yukawa couplings
and kinetic mixings for the down quarks are both consequences of this effect.
These radiative Yukawa corrections can be reduced by raising the flavon VEV on
the IR brane (at the price of some moderate tuning), or by extending the Higgs
sector. The flavor changing effects from the radiatively induced Yukawa mixing
terms are at around the current upper experimental bounds. We also show the
generic bounds on UV-brane induced flavor violating effects, and comment on
possible additional flavor violations from bulk flavor gauge bosons and the
bulk Yukawa scalars.Comment: 28 page
Teaching design in emerging countries A train-the-trainer methodology
Design disciplines have constantly evolved to keep up with the emerging demands of the 21st Century. Design education is thus called to change its methods, tools and approaches. There is an increasing interest in emerging economies in design education, especially in India, where the role of creativity, communication and technology can support social and economic development. This paper aims to present the educational approach developed in the context of the Erasmus+ KA2 project entitled âDesign and Innovation Capacity Building in India/DESINNOâ. The modernisation and internationalisation of Indian universities with innovative and contemporary design courses have been the main goals of a set of research and training activities. In this paper, the state-of-the-art methodologies in design thinking, sustainability, design research, social innovation and ethical issues in design are presented, leading to a bespoke educational approach that provides a platform for Indian design academics to apply modern educational approaches
to their specificities and needs
The s ---> d gamma decay in and beyond the Standard Model
The New Physics sensitivity of the s ---> d gamma transition and its
accessibility through hadronic processes are thoroughly investigated. Firstly,
the Standard Model predictions for the direct CP-violating observables in
radiative K decays are systematically improved. Besides, the magnetic
contribution to epsilon prime is estimated and found subleading, even in the
presence of New Physics, and a new strategy to resolve its electroweak versus
QCD penguin fraction is identified. Secondly, the signatures of a series of New
Physics scenarios, characterized as model-independently as possible in terms of
their underlying dynamics, are investigated by combining the information from
all the FCNC transitions in the s ---> d sector.Comment: 54 pages, 14 eps figure
Kaon decays at KLOE-2
I review kaon decays. I introduce the flavor problem and possible solutions. Very rare kaon decays like KâÏÎœÎœÂŻ are very important to this purpose: we study also KâÏl+lâ,KâÏÏee where chiral dynamics is important to disentangle short distance effects. We have also studied lepton flavor (universality) violation in rare kaon decays and the Bardeen Buras Gerard approach to describe the K±âϱl+lâ form factor
Estimate of B(K -> pi nu nubar) from Standard Model fits to lambda_t
We estimate B(K -> pi nu nubar) in the context of the Standard Model by
fitting for lambda_t = Vtd x V*ts of the `kaon unitarity triangle' relation. We
fit data from epsilon_K, the CP-violating parameter describing K-mixing, and
a_{psi K}, the CP-violating asymmetry in B -> J/psi K decays. Our estimate is
independent of the CKM matrix element Vcb and of the ratio of Bs to Bd mixing
frequencies. The measured value of B(K+ -> pi+ nu nubar) can be compared both
to this estimate and to predictions made from the ratio of B mixing
frequencies.Comment: 8 pages, including 6 figures. v3 includes an expanded discussion of
correlations between SM inputs to the lambda_t fit, clarifies the discussion
of the independence of this result from the ratio of B mixing frequencies,
includes minor updates to the values of SM input parameters, and includes
some new and some updated reference
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