364 research outputs found
Spontaneous CP Violating Phase as The CKM Matrix Phase
We propose that the CP violating phase in the CKM mixing matrix is identical
to the CP phases responsible for the spontaneous CP violation in the Higgs
potential. A specific multi-Higgs model with Peccei-Quinn (PQ) symmetry is
constructed to realize this idea. The CP violating phase does not vanish when
all Higgs masses become large. There are flavor changing neutral current (FCNC)
interactions mediated by neutral Higgs bosons at the tree level. However,
unlike general multi-Higgs models, the FCNC Yukawa couplings are fixed in terms
of the quark masses and CKM mixing angles. Implications for meson-anti-meson
mixing, including recent data on mixing, and neutron electric dipole
moment (EDM) are studied. We find that the neutral Higgs boson masses can be at
the order of one hundred GeV. The neutron EDM can be close to the present
experimental upper bound.Comment: 16 pages, RevTex. Several typos corrected, and one reference adde
Supersymmetric CP Violation in in Minimal Supergravity Model
Direct CP asymmetries and the CP violating normal polarization of lepton in
inclusive decay B \to X_s l^+ l^- are investigated in minimal supergravity
model with CP violating phases. The contributions coming from exchanging
neutral Higgs bosons are included. It is shown that the direct CP violation in
branching ratio, A_{CP}^1, is of {\cal{O}}(10^{-3}) for l=e, \mu, \tau. The CP
violating normal polarization for l=\mu can reach 0.5 percent when tan\beta is
large (say, 36). For l=\tau and in the case of large \tan\beta, the direct CP
violation in backward-forward asymmetry, A_{CP}^2, can reach one percent, the
normal polarization of \tau can be as large as a few percent, and both are
sensitive to the two CP violating phases, \phi_\mu and \phi_{A_0}, and
consequently it could be possible to observe them (in particular, the normal
polarization of \tau) in the future B factories.Comment: 14 pages, latex, 5 figure
New Higgs signals induced by mirror fermion mixing effects
We study the conditions under which flavor violation arises in scalar-fermion
interactions, as a result of the mixing phenomena between the standard model
and exotic fermions. Phenomenological consequences are discussed within the
specific context of a left-right model where these additional fermions have
mirror properties under the new SU(2)_R gauge group.
Bounds on the parameters of the model are obtained from LFV processes; these
results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e,
mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.
Spontaneous CP Violation in Non-Minimal Supersymmetric Models
We study the possibilities of spontaneous CP violation in the Next-to-Minimal
Supersymmetric Standard Model with an extra singlet tadpole term in the scalar
potential. We calculate the Higgs boson masses and couplings with radiative
corrections including dominant two loop terms. We show that it is possible to
satisfy the LEP constraints on the Higgs boson spectrum with non-trivial
spontaneous CP violating phases. We also show that these phases could account
for the observed value of epsilonK.Comment: 21 pages, 7 Figures in Encapsulated Postscrip
Muon anomalous magnetic moment in the standard model with two Higgs doublets
The muon anomalous magnetic moment is investigated in the standard model with
two Higgs doublets (S2HDM) motivated from spontaneous CP violation. Thus all
the effective Yukawa couplings become complex. As a consequence of the non-zero
phase in the couplings, the one loop contribution from the neutral scalar
bosons could be positive and negative relying on the CP phases. The
interference between one and two loop diagrams can be constructive in a large
parameter space of CP-phases. This will result in a significant contribution to
muon anomalous magnetic moment even in the flavor conserving process with a
heavy neutral scalar boson ( 200 GeV) once the effective muon Yukawa
coupling is large (). In general, the one loop contributions
from lepton flavor changing scalar interactions become more important. In
particular, when all contributions are positive in a reasonable parameter space
of CP phases, the recently reported 2.6 sigma experiment vs. theory deviation
can be easily explained even for a heavy scalar boson with a relative small
Yukawa coupling in the S2HDM.Comment: 8 pages, RevTex file, 5 figures, published version Phys. Rev. D 54
(2001) 11501
A New Prediction for Direct CP Violation \epsilon'/\epsilon and \Delta I = 1/2 Rule
The low energy dynamics of QCD is investigated with special attention paid to
the matching between QCD and chiral perturbation theory(ChPT), and also to some
useful algebraic chiral operator relations which survive even when we include
chiral loop corrections. It then allows us to evaluate the hadronic matrix
elements below the energy scale GeV. Based on the new
analyzes, we present a consistent prediction for both direct CP-violating
parameter and rule in the kaon decays. In
the leading approximation, the isospin amplitudes and are
found to agree well with the data, and the direct CP-violating parameter
is predicted to be large, which also confirms our early
conclusion. Its numerical value is which is no
longer sensitive to the strange quark mass due to the matching conditions.
Taking into account a simultaneous consistent analysis on the isospin
amplitudes and , the ratio is in favor of the
values .Comment: 19 pages, ReVtex, no figures, the corrected version to be published
in Phys. Rev. D . A more favorable and consistent prediction for direct CP
violation is found: epsilon'(prime) /epsilon = (20 \pm 9) x 10^-4, here the
contributions from finite meson masses and new isospin symmetry breaking
effects have been included. The uncertainties from QCD (or low energy) scale
have been considered. More references are adde
Detector Description and Performance for the First Coincidence Observations between LIGO and GEO
For 17 days in August and September 2002, the LIGO and GEO interferometer
gravitational wave detectors were operated in coincidence to produce their
first data for scientific analysis. Although the detectors were still far from
their design sensitivity levels, the data can be used to place better upper
limits on the flux of gravitational waves incident on the earth than previous
direct measurements. This paper describes the instruments and the data in some
detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial
change
The Impact of |Delta I|=5/2 Transitions in K-> pi pi Decays
We consider the impact of isospin violation on the analysis of K-> pi pi
decays. We scrutinize, in particular, the phenomenological role played by the
additional weak amplitude, of |Delta I|=5/2 in character, incurred by the
presence of isospin violation. We show that Watson's theorem is appropriate in
O(m_d-m_u), so that the inferred pi-pi phase shift at sqrt{s}=m_K determines
the strong phase difference between the I=0 and I=2 amplitudes in K-> pi pi
decay. We find the magnitude of the |Delta I|=5/2 amplitude thus implied by the
empirical branching ratios to be larger than expected from estimates of
isospin-violating strong and electromagnetic effects. We effect a new
determination of the octet and 27-plet coupling constants with
strong-interaction isospin violation and with electromagnetic effects, as
computed by Cirigliano, Donoghue, and Golowich, and find that we are unable to
resolve the difficulty. Exploring the role of |Delta I|=5/2 transitions in the
CP-violating observable epsilon'/epsilon, we determine that the presence of a
|Delta I|=5/2 amplitude impacts the empirical determination of omega, the ratio
of the real parts of the |Delta I|=3/2 to |Delta I|=1/2 amplitudes, and that it
generates a decrease in the estimation of epsilon'/epsilon.Comment: 29 pages, 1 ps fig, refs. added, to appear in Phys. Rev.
Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
We present the results of a search for new, heavy particles that decay at a
significant distance from their production point into a final state containing
charged hadrons in association with a high-momentum muon. The search is
conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV
and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS
detector operating at the Large Hadron Collider. Production of such particles
is expected in various scenarios of physics beyond the standard model. We
observe no signal and place limits on the production cross-section of
supersymmetric particles in an R-parity-violating scenario as a function of the
neutralino lifetime. Limits are presented for different squark and neutralino
masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final
version to appear in Physics Letters
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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