746 research outputs found
General rules for bosonic bunching in multimode interferometers
We perform a comprehensive set of experiments that characterize bosonic
bunching of up to 3 photons in interferometers of up to 16 modes. Our
experiments verify two rules that govern bosonic bunching. The first rule,
obtained recently in [1,2], predicts the average behavior of the bunching
probability and is known as the bosonic birthday paradox. The second rule is
new, and establishes a n!-factor quantum enhancement for the probability that
all n bosons bunch in a single output mode, with respect to the case of
distinguishable bosons. Besides its fundamental importance in phenomena such as
Bose-Einstein condensation, bosonic bunching can be exploited in applications
such as linear optical quantum computing and quantum-enhanced metrology.Comment: 6 pages, 4 figures, and supplementary material (4 pages, 1 figure
Effect of Ingested Interferon-α on β-Cell Function in Children With New-Onset Type 1 Diabetes
Correção total inicial e parcelada anual sob diferentes doses de potássio em um Latossolo Vermelho dos Cerrados.
Efeito da densidade de Brachiaria ruziziensis na germinação carpogênica de escleródios em área naturalmente infestada por Sclerotinia sclerotiorum.
Entre as dificuldades para o controle do mofo branco, está a sobrevivência de escleródios do patógeno Sclerotinia sclerotiorum no solo por vários anos, que dificilmente são afetados por fungicidas ou por várias práticas culturais. Estes escleródios, porém, podem ser mortos por esgotamento após germinação ou parasitismo. Em um experimento realizado em Jataí, GO, avaliou-se a germinação de escleródios e posterior produção de apotécios, em tratamentos sem cobertura do solo, e sob cultivo de Brachiaria ruziziensis estabelecida em março de 2008, com 150, 300, 450 ou 600 pontos de valor cultural (PVC)
Flavour physics from an approximate U(2)^3 symmetry
The quark sector of the Standard Model exhibits an approximate U(2)^3 flavour
symmetry. This symmetry, broken in specific directions dictated by minimality,
can explain the success of the Cabibbo-Kobayashi-Maskawa picture of flavour
mixing and CP violation, confirmed by the data so far, while allowing for
observable deviations from it, as expected in most models of ElectroWeak
Symmetry Breaking. Building on previous work in the specific context of
supersymmetry, we analyze the expected effects and we quantify the current
bounds in a general Effective Field Theory framework. As a further relevant
example we then show how the U(2)^3 symmetry and its breaking can be
implemented in a generic composite Higgs model and we make a first analysis of
its peculiar consequences. We also discuss how some partial extension of U(2)^3
to the lepton sector can arise, both in general and in composite Higgs models.
An optimistic though conceivable interpretation of the considerations developed
in this paper gives reasons to think that new physics searches in the flavour
sector may be about to explore an interesting realm of phenomena.Comment: 29 pages, 5 figure
A consistent picture for large penguins in D -> pi+ pi-, K+ K-
A long-standing puzzle in charm physics is the large difference between the
D0 -> K+ K- and D0 -> pi+ pi- decay rates. Recently, the LHCb and CDF
collaborations reported a surprisingly large difference between the direct CP
asymmetries, Delta A_CP, in these two modes. We show that the two puzzles are
naturally related in the Standard Model via s- and d-quark "penguin
contractions". Their sum gives rise to Delta A_CP, while their difference
contributes to the two branching ratios with opposite sign. Assuming nominal
SU(3) breaking, a U-spin fit to the D0 -> K+ pi-, pi+ K-, pi+ pi-, K+ K- decay
rates yields large penguin contractions that naturally explain Delta A_CP.
Expectations for the individual CP asymmetries are also discussed.Comment: 24 pages, 8 figure
An upper bound on the Kaon B-parameter and Re(epsilon_K)
New precise data in B physics and theoretical developments in K physics lead
us to reconsider the weak K^0-\bar{K}^0 transition from a large-N_c viewpoint,
N_c being the number of colors. In this framework, we infer an upper limit on
\hat{B}_K and the Kaon indirect CP violation.Comment: 11 pages, 4 figures. V2 : Minor corrections, final version accepted
for publication in JHE
Flavour constraints on scenarios with two or three heavy squark generations
We re-assess constraints from flavour-changing neutral currents in the kaon
system on supersymmetric scenarios with a light gluino, two heavy generations
of squarks and a lighter third generation. We compute for the first time limits
in scenarios with three heavy squark families, taking into account QCD
corrections at the next-to-leading order. We compare our limits with those in
the case of two heavy families. We use the mass insertion approximation and
consider contributions from gluino exchange to constrain the mixing between the
first and second squark generation. While it is not possible to perform a
general analysis, we assess the relevance of each kind of flavour- and
CP-violating parameters. We also provide ready to use magic numbers for the
computation of the Wilson coefficients at 2 GeV for these scenarios.Comment: 23 pages, 14 figures; v3: matches published version (contains
improvements in the presentation and clarifications
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