593 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
Gauged flavour symmetry for the light generations
We study the phenomenology of a model where an SU(2)^3 flavour symmetry
acting on the first two generation quarks is gauged and Yukawa couplings for
the light generations are generated by a see-saw mechanism involving heavy
fermions needed to cancel flavour-gauge anomalies. We find that, in constrast
to the SU(3)^3 case studied in the literature, most of the constraints related
to the third generation, like electroweak precision bounds or B physics
observables, can be evaded, while characteristic collider signatures are
predicted.Comment: 16 pages, 3 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
On the Standard Model prediction for BR(B{s,d} to mu+ mu-)
The decay Bs to mu+ mu- is one of the milestones of the flavor program at the
LHC. We reappraise its Standard Model prediction. First, by analyzing the
theoretical rate in the light of its main parametric dependence, we highlight
the importance of a complete evaluation of higher-order electroweak
corrections, at present known only in the large-mt limit, and leaving sizable
dependence on the definition of electroweak parameters. Using insights from a
complete calculation of such corrections for K to pi bar{nu} nu decays, we find
a scheme in which NLO electroweak corrections are likely to be negligible.
Second, we address the issue of the correspondence between the initial and the
final state detected by the experiments, and those used in the theoretical
prediction. Particular attention is devoted to the effect of the soft
radiation, that has not been discussed for this mode in the previous
literature, and that can lead to O(10%) corrections to the decay rate. The
"non-radiative" branching ratio (that is equivalent to the branching ratio
fully inclusive of bremsstrahlung radiation) is estimated to be (3.23 +/- 0.27)
x 10^{-9} for the flavor eigenstate, with the main uncertainty resulting from
the value of f_{Bs}, followed by the uncertainty due to higher order
electroweak corrections. Applying the same strategy to Bd to mu+ mu-, we find
for its non-radiative branching ratio (1.07 +/- 0.10) x 10^{-10}.Comment: 15 pages. v3: very minor changes to match the journal version (EPJC
Jekyll and Hyde: men's constructions of feminism and feminists
Research and commentary on men's responses to feminism has demonstrated the range of ways in which men have mobilised both against and for feminist principles. This paper argues that further analyses of men's responses require a sophisticated theory of discourse acknowledging the fragmented and contradictory nature of representation. A corpus of men's talk on feminism and feminists was studied to identify the pervasive patterns in men's accounting and regularities in rhetorical organisation. Material from two samples of men was included: a sample of white middle-class 17-18 year old school students and a sample of 60 interviews with a more diverse sample of older men aged 20 to 64. Two interpretative repertoires of feminism and feminists were identified. These set up a 'Jekyll and Hyde' binary and positioned feminism along with feminists very differently as reasonable versus extreme and monstrous. Both repertoires tended to be deployed together and the paper explores the ideological and interactional consequences of typical deployments along with the identity work accomplished by the men as they positioned themselves in relation to these
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