37,527 research outputs found
CP Violation in Fourth Generation Quark Decays
We show that, if a fourth generation is discovered at the Tevatron or LHC,
one could study CP violation in b' \to s decays. Asymmetries could reach 30%
for b'\to sZ for m_{b'} \lesssim 350 GeV, while it could be greater than 50%
for b'\to s\gamma and extend to higher m_{b'}. Branching ratios are
10^{-3}--10^{-5}, and CPV measurement requires tagging. Once measured, however,
the CPV phase can be extracted with little theoretical uncertainty.Comment: 4 pages, 7 eps figure
Measuring the Fourth Generation b --> s Quadrangle at the LHC
We show that simultaneous precision measurement of the CP-violating phase in
time-dependent Bs --> J/psi phi study and the Bs --> mu+ mu- rate, together
with measuring m_t' by direct search at the LHC, would determine
V_{t's}^*V_{t'b} and therefore the b --> s quadrangle in the four-generation
standard model. The forward-backward asymmetry in B --> K* l+ l- provides
further discrimination.Comment: 6 pages, 7 figures, revised based on LHC results released in this
summer, to appear in PR
Higgs Mass Constraints on a Fourth Family: Upper and Lower Limits on CKM Mixing
Limits on the Higgs boson mass restrict CKM mixing of a possible fourth
family beyond the constraints previously obtained from precision electroweak
data alone. Existing experimental and theoretical bounds on the Higgs mass
already significantly restrict the allowed parameter space. Zero CKM mixing is
excluded and mixing of order the Cabibbo angle is allowed. Upper and lower
limits on 3-4 CKM mixing are exhibited as a function of the Higgs mass. We use
the default inputs of the Electroweak Working Group and also explore the
sensitivity of both the three and four family fits to alternative inputs.Comment: Adds discussion of alternative fourth family masses, including new
best fit, and reconciles with published versio
Complementarity of Semileptonic to and Decays in the Standard Model with Fourth Generation
The decays are
analyzed in the Standard Model extended to fourth generation of quarks (SM4).
The decay rate, forward-backward asymmetry, lepton polarization asymmetries and
the helicity fractions of the final state meson are obtained
using the form factors calculated in the light cone sum rules (LCSR) approach.
We have utilized the constraints on different fourth generation parameters
obtained from the experimental information on , and decays and from
the electroweak precision data to explore their impact on the decay. We find that the values of above mentioned
physical observables deviate deviate significantly from their minimal SM
predications. We also identify a number of correlations between various
observables in and decays. Therefore a combined analysis of these two
decays will compliment each other in the searches of SM4 effects in flavor
physics.Comment: 28 pages, 12 figure
No association of CTLA-4 polymorphisms with susceptibility to Behcet disease
Background: Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a key negative regulator of T lymphocytes and has been shown to be associated with a number of autoimmune diseases. The present study was performed to assess the association between CTLA-4 polymorphisms and Behcet disease (BD) in Chinese patients. Methods: Two hundred and twenty-eight BD patients and 207 controls were analysed for four single nucleotide polymorphisms (SNPs) (21661A/G, 2318C/T, + 49G/A and CT60G/A) in the CTLA-4 gene by PCR-restriction fragment length polymorphism (RFLP) analysis. The association between SNP +49A/G and BD in Chinese population as well as other ethnic groups was analysed by meta-analysis. Results: No association could be detected between CTLA-4 SNPs or haplotypes and BD. Also, no association was observed between CTLA-4 polymorphisms and BD subgroups, stratified by clinical features. A meta-analysis showed that there was no heterogeneity between studies (p = 0.60, I-2 = 0%) and that CTLA-4 SNP + 49 was not associated with BD (overall effect: Z = 0.26, p = 0.79). Conclusion: This study and a meta-analysis failed to demonstrate any association between the tested CTLA-4 polymorphisms and B
On Singularity Formation of a Nonlinear Nonlocal System
We investigate the singularity formation of a nonlinear nonlocal system. This
nonlocal system is a simplified one-dimensional system of the 3D model that was
recently proposed by Hou and Lei in [13] for axisymmetric 3D incompressible
Navier-Stokes equations with swirl. The main difference between the 3D model of
Hou and Lei and the reformulated 3D Navier-Stokes equations is that the
convection term is neglected in the 3D model. In the nonlocal system we
consider in this paper, we replace the Riesz operator in the 3D model by the
Hilbert transform. One of the main results of this paper is that we prove
rigorously the finite time singularity formation of the nonlocal system for a
large class of smooth initial data with finite energy. We also prove the global
regularity for a class of smooth initial data. Numerical results will be
presented to demonstrate the asymptotically self-similar blow-up of the
solution. The blowup rate of the self-similar singularity of the nonlocal
system is similar to that of the 3D model.Comment: 28 pages, 9 figure
Window on Higgs Boson: Fourth Generation Decays Revisited
Direct and indirect searches of the Higgs boson suggest that 113 GeV
170 GeV is likely. With the LEP era over and the
Tevatron Run II search via arduous, we revisit a case where
or jets could arise via strong pair
production. In contrast to 10 years ago, the tight electroweak constraint on
-- (hence --) splitting reduces FCNC
, rates, making naturally competitive.
Such a "cocktail solution" is precisely the mix that could evade the CDF search
for , and the may well be lurking below the top. In
light of the Higgs program, this two-in-one strategy should be pursued.Comment: 4 pages, RevTex, 4 eps figures, One more figure, version to be
published in Phys. Rev.
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