596 research outputs found
Two body decays of the -quark: Applications to direct CP violation, searches for electro-weak penguins and new physics
A systematic experimental search for two-body hadronic decays of the b-quark
of the type b to quark + meson is proposed. These reactions have a well defined
experimental signature and they should be theoretically cleaner compared to
exclusive decays. Many modes have appreciable branching ratios and partial rate
asymmetries may also be quite large (about 8-50%) in several of them. In a few
cases electroweak penguins appear to be dominant and may be measurable. CP
violating triple correlation asymmetries provide a clean test of the Standard
Model.Comment: 12 pages 1 figure 1 tabl
Obtaining CKM Phase Information from B Penguin Decays
We discuss a method for extracting CP phases from pairs of B decays which are
related by flavor SU(3). One decay (B0 -> M1 M2) receives a significant bbar ->
dbar penguin contribution. The second (B' -> M1' M2') has a significant bbar ->
sbar penguin contribution, but is dominated by a single amplitude. CP phase
information is obtained using the fact that the B' -> M1' M2' amplitude is
related by SU(3) to a piece of the B0 -> M1 M2 amplitude. The leading-order
SU(3)-breaking effect (~25%) responsible for the main theoretical error can be
removed. For some decay pairs, it can be written in terms of known decay
constants. In other cases, it involves a ratio of form factors. However, this
form-factor ratio can either be measured experimentally, or eliminated by
considering a double ratio of amplitudes. In all cases, one is left only with a
second-order effect, ~5%. We find twelve pairs of B decays to which this method
can be applied. Depending on the decay pair, we estimate the total theoretical
error in relating the B' -> M1' M2' and B0 -> M1 M2 amplitudes to be between 5%
and 15%. The most promising decay pairs are Bd -> pi+ pi- and Bu+ -> K0 pi+,
and Bd -> D+ D- and Bd -> Ds+ D- or Bu+ -> Ds+ D0bar.Comment: 38 pages, JHEP format, no figures. Comments added to text regarding
most promising decay pairs; references added; conclusions unchange
Extracting information on CKM phases, electro-weak penguins and new physics from B --> VV decays
We derive constraints for modes ($V= vector meson) that allow
aquantitative assessment of the contributions from electroweak penguins (EWP)
and/or new physics. Interplay of direct CP with oscillation studies then leads
to the extraction of the angles alpha and gamma, using B--> K* omega rho and
B--> rho omega (phi) respectively, if by using our constraint equations it can
be experimentally demonstrated that color-suppressed EWP are small.Comment: 12 pages, 0 figures; revised and expande
The Possibility of Large Direct CP Violation in B to K pi-Like Modes Due to Long Distance Rescattering Effects and Implications for the Angle gamma
We consider the strong rescattering effects that can occur in the decays such
as B -> K pi, K* pi, K rho... and their impact on direct CP violation in these
modes. First we discuss, in general, how the CPT theorem constrains the
resulting pattern of partial rate asymmetries leading to different brands of
direct CP. Traditional discussions have centered around the absorptive part of
the penguin graph which has Delta I=0 in b -> s transitions and as a result
causes ``simple'' CP violation; long-distance final state rescattering effects,
in general, will lead to a different pattern of CP: ``compound'' CP violation.
Predictions of simple CP are quite distinct from that of compound CP. Final
states rescattering phases in B decays are unlikely to be small possibly
causing large compound CP violating partial rate asymmetries in these modes.
CPT theorem requires a cancellation of PRA due to compound CP amongst the
states themselves; thus there can be no net cancellation with other
states such as K*\pi, K\rho etc. Therefore, each class of such modes, namely K
pi, K rho, K^*pi, K a_1 etc. can have large direct CP emanating from
rescattering effects. Various repercussions for the angle are also
discussed.Comment: 45 pages; 5 figures. In replacement we have : 1) corrected many
typos, 2) added references, 3) decided to subdivide Simple CP into 2
categories and 4) Modified figure 3 to explain tha
ELECTROWEAK PENGUINS AND TWO-BODY B DECAYS
We discuss the role of electroweak penguins in decays to two light
pseudoscalar mesons. We confirm that the extraction of the weak phase
through the isospin analysis involving decays is largely
unaffected by such operators. However, the methods proposed to obtain weak and
strong phases by relating , and decays
through flavor SU(3) will be invalidated if electroweak penguins are large. We
show that, although the introduction of electroweak penguin contributions
introduces no new amplitudes of flavor SU(3), there are a number of ways to
experimentally measure the size of such effects. Finally, using SU(3) amplitude
relations we present a new way of measuring the weak angle which holds
even in the presence of electroweak penguins.Comment: 18 pages, 3 figures, LaTeX file. The full postscript manuscript is
available by anonymous ftp at
ftp://lpsvsh.lps.umontreal.ca/theorie/hep-ph/EWpenguins.ps (a VAX so use the
format theorie.hep-ph if you change by more than one directory at a time
Current Options for the Treatment of Food Allergy
Food allergy is increasing in prevalence; as a result, there is intense focus on developing safe and effective therapies. Current methods of specific immunotherapy include oral, sublingual, and epicutaneous, while nonspecific methods that have been investigated include: Chinese herbal medicine, probiotics, and anti-IgE antibodies. Although some studies have demonstrated efficacy in inducing desensitization, questions regarding safety and the potential for achieving immune tolerance remain. Although some of these therapies demonstrate promise, further investigation is required before their incorporation into routine clinical practice
Long-term treatment with egg oral immunotherapy enhances sustained unresponsiveness that persists after cessation of therapy
We previously reported results of a randomized, placebo-controlled study of egg oral immunotherapy (eOIT), in which 27.5% of subjects achieved sustained unresponsiveness (SU) after 2 years. Here we report results of treatment through 4 years and long-term follow-up
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