229 research outputs found
U-Spin Symmetry in Charmless B Decays
We prove a general theorem about equal CP rate differences within pairs of
U-spin related charmless and decays. Large deviations from equalities
would be evidence for new physics. Six pairs of decays into two pseudoscalar
mesons are identified where such relations hold. Ratios of corresponding rate
differences and certain ratios of rates measure U-spin breaking. These
processes provide useful information on the weak phase . Applications of U-spin symmetry to other decays are discussed.Comment: A few typos corrected, to appear in Phys. Lett.
Constraints on the phase and new physics from Decays
Recent results from CLEO on indicate that the phase may
be substantially different from that obtained from other fit to the KM matrix
elements in the Standard Model. We show that extracted using is sensitive to new physics occurring at loop level. It provides
a powerful method to probe new physics in electroweak penguin interactions.
Using effects due to anomalous gauge couplings as an example, we show that
within the allowed ranges for these couplings information about
obtained from can be very different from the Standard
Model prediction.Comment: Revised version with analysis done using new data from CLEO. RevTex,
11 Pages with two figure
Increased EMRSA-15 health-care worker colonization demonstrated in retrospective review of EMRSA hospital outbreaks
Background:Health care worker (HCW) colonization with methicillin resistant Staphylococcus aureus (MRSA) is a documented cause of hospital outbreaks and contributes to ongoing transmission. At Royal Perth Hospital (RPH) it had been anecdotally noted that the increasing prevalence of EMRSA-15 appeared to be associated with increased HCW colonization compared with Aus2/3-EMRSA. Hence we compared HCW colonization rates during outbreaks of EMRSA-15 and Aus2/3-EMRSA at a single institution.Methods:We performed a retrospective review of EMRSA-15 and Aus2/3-EMRSA outbreaks from 2000 –2009 at RPH, a quaternary hospital in Western Australia. Outbreak files were reviewed and relevant data extracted. Results:Ten EMRSA-15 outbreaks were compared with seven Aus2/3 outbreaks. The number of patients colonized was similar between EMRSA-15 and Aus2/ 3-EMRSA outbreaks (median 7 [range 3 – 20] and 11 [5 – 26], respectively; P = 0.07) but the number of HCWs colonized was significantl y higher in EMRSA-15 outbreaks compared to Aus2/3-EMRSA outbreaks (median 4 [range 0 – 15] and 2 [1-3], respectively; P = 0.013). The percentage of HCWs colonized was also higher in EMRSA-15 outbreaks versus Aus2/3-EMRSA outbreaks (median 3.4% [range 0 – 5.5%] and 0.81% [0.56 – 2.2%], respectively; P= 0.013).Conclusions:This study demonstrates a higher level of HCW colonization during EMRSA-15 outbreaks compared with Aus2/3-EMRSA outbreaks. This finding suggests that MRSA vary in their ability to colonize HCWs and contribute to outbreaks. MRSA type should be determined during outbreaks and future research should investigate the mechanisms by which EMRSA-15 contributes to increased HCW colonization
Final State Rescattering and Color-suppressed \bar B^0-> D^{(*)0} h^0 Decays
The color-suppressed \bar B^0-> D^{(*)0}\pi^0, D^{(*)0}\eta, D^0\omega decay
modes have just been observed for the first time. The rates are all larger than
expected, hinting at the presence of final state interactions. Considering \bar
B^0-> D^{(*)0}\pi^0 mode alone, an elastic D^{(*)}\pi -> D^{(*)}\pi
rescattering phase difference \delta \equiv \delta_{1/2} - \delta_{3/2} \sim
30^\circ would suffice, but the \bar B^0-> D^{(*)0}\eta, D^0\omega modes compel
one to extend the elastic formalism to SU(3) symmetry. We find that a universal
a_2/a_1=0.25 and two strong phase differences 20^\circ \sim \theta < \delta <
\delta^\prime \sim 50^\circ can describe both DP and D^*P modes rather well;
the large phase of order 50^\circ is needed to account for the strength of {\it
both} the D^{(*)0}\pi^0 and D^{(*)0}\eta modes. For DV modes, the nonet
symmetry reduces the number of physical phases to just one, giving better
predictive power. Two solutions are found. We predict the rates of the \bar
B^0-> D^{+}_s K^-, D^{*+}_s K^-, D^0\rho^0, D^+_s K^{*-} and D^0\phi modes, as
well as \bar B^0-> D^{0}\bar K^0, D^{*0}\bar K^0, D^{0}\bar K^{*0} modes. The
formalism may have implications for rates and CP asymmetries of charmless
modes.Comment: REVTeX4, 18 pages, 5 figures, to appear in Phys. Rev.
Modular Invariants in the Fractional Quantum Hall Effect
We investigate the modular properties of the characters which appear in the
partition functions of nonabelian fractional quantum Hall states. We first give
the annulus partition function for nonabelian FQH states formed by spinon and
holon (spinon-holon state). The degrees of freedom of spin are described by the
affine SU(2) Kac-Moody algebra at level . The partition function and the
Hilbert space of the edge excitations decomposed differently according to
whether is even or odd. We then investigate the full modular properties of
the extended characters for nonabelian fractional quantum Hall states. We
explicitly verify the modular invariance of the annulus grand partition
functions for spinon-holon states, the Pfaffian state and the 331 states. This
enables one to extend the relation between the modular behavior and the
topological order to nonabelian cases. For the Haldane-Rezayi state, we find
that the extended characters do not form a representation of the modular group,
thus the modular invariance is broken.Comment: Latex,21 pages.version to appear in Nucl.Phys.
Topological Phase Transition in the Quantum Hall Effect
The double layer fractional quantum Hall system is studied using
the edge state formalism and finite-size diagonalization subject to periodic
boundary conditions. Transitions between three different ground states are
observed as the separation as well as the tunneling between the two layers is
varied. Experimental consequences are discussed.Comment: 11 pages, REVTEX v3.0, 7 figure
Combining CP Asymmetries in Decays
We prove an approximate relation, to leading order in dominant terms, between
CP-violating rate differences in and
. We show how data from these two processes may be
combined in order to enhance the significance of a nonzero result.Comment: 9 pages, latex, no figures, submitted to Phys. Rev. Letters, revise
First limit on inclusive decay and constraints on new physics
The inclusive decay rate, on which no experimental
bound exists to date, can be constrained by searching for large missing energy
events in decays. Carefully examining the experimental and theoretical
aspects of such an analysis, we argue that the published ALEPH limit on \BR(B
\to \tau \bar\nu) implies, conservatively, the bound \BR(B \to X_s \nu
\bar\nu)<3.9\times10^{-4}, which is less than one order of magnitude above the
standard model prediction. The LEP collaborations could significantly improve
this bound by a dedicated experimental analysis. We study the constraints this
new limit imposes on various extensions of the standard model. We derive new
bounds on the couplings of third generation fermions in models with
leptoquarks, and in supersymmetric models without R-parity. We also constrain
models where new gauge bosons are coupled dominantly to the third generation,
such as TopColor models and models based on horizontal gauge symmetries. For
models which predict an enhanced effective vertex, the constraint from is competitive with the limits from inclusive and
exclusive decays.Comment: 43 pages (paper) + 3 pages (erratum), REVTeX, no figures. Erratum
added (Paper unchanged). Two effects neglected in the original analysis are
discussed in the Erratum. The numerical estimate of the limit on the
branching ratio is weaker by about a factor of thre
The impact of point mutations in the human androgen receptor : classification of mutations on the basis of transcriptional activity
Peer reviewedPublisher PD
On Large Final-State Phases in Heavy Meson Decays
An attempt is made to identify circumstances under which the weak decays of
and mesons may display large differences between eigenphases of strong
final-state interactions. There are several cases in which rescattering from
other final states appears to enhance decay rates with respect to estimates
based on the factorization hypothesis.Comment: 24 pages, latex, 4 figures, to be submitted to Phys. Rev.
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