3,008 research outputs found
Constraining the CKM Parameters using CP Violation in semi-leptonic B Decays
We discuss the usefulness of the CP violating semi-leptonic asymmetry a_{SL}
not only as a signal of new physics, but also as a tool in constraining the CKM
parameters. We show that this technique could yield useful results in the first
years of running at the B factories. We present the analysis graphically in
terms of M_{12}, the dispersive part of the B-Bbar mixing amplitude. This is
complementary to the usual unitarity triangle representation and often allows a
cleaner interpretation of the data.Comment: 15 pages REVTEX, 7 figure
Leptonic Flavor and CP Violation
We discuss how neutrino oscillation experiments can probe new sources of
leptonic flavor and CP violation.Comment: 8 pages, latex, no figures. Invited talk given at KAON 2001, Pisa,
Italy, June 12 - 17, 200
Calibrating the Mixing Length Parameter for a Red Giant Envelope
Two-dimensional hydrodynamical simulations were made to calibrate the mixing
length parameter for modeling red giant's convective envelope. As was briefly
reported in Asida & Tuchman (97), a comparison of simulations starting with
models integrated with different values of the mixing length parameter, has
been made. In this paper more results are presented, including tests of the
spatial resolution and Large Eddy Simulation terms used by the numerical code.
The consistent value of the mixing length parameter was found to be 1.4, for a
red giant of mass 1.2 solar-mass, core mass of 0.96 solar-mass, luminosity of
200 solar-luminosities, and metallicity Z=0.001.Comment: 18 pages, 1 table, 13 figures. Accepted for publication in Ap.
Constraining New Physics with the CDF Measurement of CP Violation in
Recently, the CDF collaboration has reported a measurement of the CP
asymmetry in the decay: . We
analyze the constraints that follow from this measurement on the size and the
phase of contributions from new physics to B-\barB mixing. Defining the
relative phase between the full amplitude and the Standard Model
contribution to be , we find a new bound: \sin2\theta_d\gsim-0.6
(-0.87) at one sigma (95% CL). Further implications for the CP asymmetry in
semileptonic B decays are discussed.Comment: 13 pages, harvmac, 3 figures; v2: a discussion of new physics effects
on tree level decays added; references added; accepted for publication in
Physical Review Letter
Repercussions of the COVID-19 pandemic on child and adolescent mental health: A matter of concern—A joint statement from EAP and ECPCP
COVID-19 pandemic and the consequent rigid social distancing measures implemented, including school closures, have heavily impacted children's and adolescents' psychosocial wellbeing, and their mental health problems significantly increased. However, child and adolescent mental health were already a serious problem before the Pandemic all over the world. COVID-19 is not just a pandemic, it is a syndemic and mentally or socially disadvantaged children and adolescents are the most affected. Non-Communicable Diseases (NCDs) and previous mental health issues are an additional worsening condition. Even though many countries have responded with decisive efforts to scale-up mental health services, a more integrated and community-based approach to mental health is required. EAP and ECPCP makes recommendations to all the stakeholders to take action to promote, protect and care for the mental health of a generation
Double Exponential Instability of Triangular Arbitrage Systems
If financial markets displayed the informational efficiency postulated in the
efficient markets hypothesis (EMH), arbitrage operations would be
self-extinguishing. The present paper considers arbitrage sequences in foreign
exchange (FX) markets, in which trading platforms and information are
fragmented. In Kozyakin et al. (2010) and Cross et al. (2012) it was shown that
sequences of triangular arbitrage operations in FX markets containing 4
currencies and trader-arbitrageurs tend to display periodicity or grow
exponentially rather than being self-extinguishing. This paper extends the
analysis to 5 or higher-order currency worlds. The key findings are that in a
5-currency world arbitrage sequences may also follow an exponential law as well
as display periodicity, but that in higher-order currency worlds a double
exponential law may additionally apply. There is an "inheritance of
instability" in the higher-order currency worlds. Profitable arbitrage
operations are thus endemic rather that displaying the self-extinguishing
properties implied by the EMH.Comment: 22 pages, 22 bibliography references, expanded Introduction and
Conclusion, added bibliohraphy reference
Benefits of Artificially Generated Gravity Gradients for Interferometric Gravitational-Wave Detectors
We present an approach to experimentally evaluate gravity gradient noise, a
potentially limiting noise source in advanced interferometric gravitational
wave (GW) detectors. In addition, the method can be used to provide sub-percent
calibration in phase and amplitude of modern interferometric GW detectors.
Knowledge of calibration to such certainties shall enhance the scientific
output of the instruments in case of an eventual detection of GWs. The method
relies on a rotating symmetrical two-body mass, a Dynamic gravity Field
Generator (DFG). The placement of the DFG in the proximity of one of the
interferometer's suspended test masses generates a change in the local
gravitational field detectable with current interferometric GW detectors.Comment: 16 pages, 4 figure
More on deviation from bi-maximal neutrino mixing
We study the case of presenting the exact bi-maximal mixing form with
inducing the deviation from the bi-maximal mixing in the final form of
the Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing, . We
will show that such possibility will lead to a democratic texture for the
charged lepton mass matrix and to a neutrino mass matrix with four null
entries.Comment: a scenario realizing our proposal is added, new references added, to
be published in J.Phys.
Neutrino Parameters, Abelian Flavor Symmetries, and Charged Lepton Flavor Violation
Neutrino masses and mixings have important implications for models of fermion
masses, and, most directly, for the charged lepton sector. We consider
supersymmetric Abelian flavor models, where neutrino mass parameters are
related to those of charged leptons and sleptons. We show that processes such
as \tau to \mu\gamma, \mu to e\gamma and \mu-e conversion provide interesting
probes. In particular, some existing models are excluded by current bounds,
while many others predict rates within reach of proposed near future
experiments. We also construct models in which the predicted rates for charged
lepton flavor violation are below even the proposed experimental sensitivities,
but argue that such models necessarily involve loss of predictive power.Comment: 27 pages, refs added, published versio
Non-factorizable Contributions to Decays
We investigate to what extent the experimental information on
branching fractions and CP asymmetries can be used to better understand the QCD
dynamics in these decays. For this purpose we decompose the independent isospin
amplitudes into factorizable and non-factorizable contributions. The former can
be estimated within the framework of QCD factorization for exclusive
decays. The latter vanish in the heavy-quark limit, , and are
treated as unknown hadronic parameters. We discuss at some length in which way
the non-factorizable contributions are treated in different theoretical and
phenomenological frameworks. We point out the potential differences between the
phenomenological treatment of power-corrections in the ``BBNS approach'', and
the appearance of power -suppressed operators in soft-collinear effective
theory (SCET). On that basis we define a handful of different (but generic)
scenarios where the non-factorizable part of isospin amplitudes is parametrized
in terms of three or four unknowns, which can be constrained by data. We also
give some short discussion on the implications of our analysis for decays. In particular, since non-factorizable QCD effects in
may be large, we cannot exclude sizeable non-factorizable effects, which
violate flavour symmetry, or even isospin symmetry (via long-distance
QED effects). This may help to explain certain puzzles in connection with
isospin-violating observables in decays.Comment: published version, minor correction
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