205 research outputs found
Measurement of phi_3 with Dalitz Plot Analysis of B+=>D(*)K(*)+ Decay
Results from the Belle and BaBar experiments on measurement of the weak angle
phi_3 using a Dalitz plot analysis of the KSpi+pi- decay of the neutral D meson
from the B+=>D(*)K(*)+ process are presented. The method employs the
interference between D0 and D0bar to extract the angle phi_3, strong phase
delta and the ratio r of suppressed and allowed amplitudes.Comment: 4 pages, 3 figures. To appear in the proceedings of the 7th
International Conference on Hyperons, Charm And Beauty Hadrons (BEACH 2006),
2nd-8th July 2006, Lancaster, Englan
B\to X_s\gamma, X_s l^+ l^- decays and constraints on the mass insertion parameters in the MSSM
In this paper, we study the upper bounds on the mass insertion parameters
in the minimal supersymmetric standard model (MSSM).
We found that the information from the measured branching ratio of decay can help us to improve the upper bounds on the mass insertions
parameters \left (\delta^{u,d}_{AB})_{3j,i3}. Some regions allowed by the
data of are excluded by the requirement of a SM-like
imposed by the data of .Comment: 16 pages, 5 eps figure files, typos remove
Variational Study of Weakly Coupled Triply Heavy Baryons
Baryons made of three heavy quarks become weakly coupled, when all the quarks
are sufficiently heavy such that the typical momentum transfer is much larger
than Lambda_QCD. We use variational method to estimate masses of the
lowest-lying bcc, ccc, bbb and bbc states by assuming they are Coulomb bound
states. Our predictions for these states are systematically lower than those
made long ago by Bjorken.Comment: 31 pages, 5 figure
Branching Ratio and CP Asymmetry of B_s \to K^*_0(1430)\pi Decays in the PQCD Approach
In the two-quark model supposition for , the branching ratios
and the direct CP-violating asymmetries for decays are studied by employing the
perturbative QCD factorization approach. We find that although these two decays
are both tree-dominated, the ratio of their penguin to tree contributions are
very different: there is only a few percent for the decay , while about 37% in scenario I, even 51% in scenario II
for the decay . It results that these two
decays have very different values in the branching ratios and the direct CP
asymmetries. The branching ratio of the decay is at the order of , and its direct CP asymmetry
is about (20-30)%. While for the decay , its
direct CP-violating asymmetry is very large and about 90%, but it is difficult
to measure it, because the branching ratio for this channel is small and only
order.Comment: 8pages, 2figure
Transitions in Family-dependent Models
We analyze flavor-changing-neutral-current (FCNC) effects in the
transitions that are induced by family non-universal gauge symmetries.
After systematically developing the necessary formalism, we present a
correlated analysis for the processes. We adopt a
model-independent approach in which we only require family-universal charges
for the first and second generations and small fermion mixing angles. We
analyze the constraints on the resulting parameter space from
mixing and the time-dependent CP asymmetries of the penguin-dominated decays. Our results indicate that the
currently observed discrepancies in some of these modes with respect to the
Standard Model predictions can be consistently accommodated within this general
class of models.Comment: 36 pages, 11 figure
Lepton non-universality at LEP and charged Higgs
A recent analysis of the LEP data shows an interesting deviation from lepton
universality in W boson decays. An excess at the level of 2.8 sigma is found in
the tau mode branching ratio with respect to the other two modes. It is
suggested that this seeming lepton non-universality might stem from pair
production of charged Higgs bosons almost degenerate with W, that
preferentially decay to heavy fermions. It is shown that the deviation can be
reduced to 1.4 sigma in two Higgs doublet model I without any conflict with the
existing direct or indirect constraints. This conclusion is largely independent
of tan beta, the ratio of Higgs vacuum expectation values. This scenario can be
tested at the forthcoming international linear collider.Comment: 16 pages, published version with minor change
Prospects for the direct detection of neutralino dark matter in orbifold scenarios
We analyse the phenomenology of orbifold scenarios from the heterotic
superstring, and the resulting theoretical predictions for the direct detection
of neutralino dark matter. In particular, we study the parameter space of these
constructions, computing the low-energy spectrum and taking into account the
most recent experimental and astrophysical constraints, as well as imposing the
absence of dangerous charge and colour breaking minima. In the remaining
allowed regions the spin-independent part of the neutralino-proton cross
section is calculated and compared with the sensitivity of dark matter
detectors. In addition to the usual non universalities of the soft terms in
orbifold scenarios due to the modular weight dependence, we also consider
D-term contributions to scalar masses. These are generated by the presence of
an anomalous U(1), providing more flexibility in the resulting soft terms, and
are crucial in order to avoid charge and colour breaking minima. Thanks to the
D-term contribution, large neutralino detection cross sections can be found,
within the reach of projected dark matter detectors.Comment: 51 pages, 25 figure
Constraining the MSSM with universal gaugino masses and implication for searches at the LHC
Using a Markov chain Monte Carlo approach, we find the allowed parameter
space of a MSSM model with seven free parameters. In this model universality
conditions at the GUT scale are imposed on the gaugino sector. We require in
particular that the relic density of dark matter saturates the value extracted
from cosmological measurements assuming a standard cosmological scenario. We
characterize the parameter space of the model that satisfies experimental
constraints and illustrate the complementarity of the LHC searches, B-physics
observables and direct dark matter searches for further probing the parameter
space of the model. We also explore the different decay chains expected for the
coloured particles that would be produced at LHC.Comment: 29 pages, 11 figure
Charmless hadronic decays in the perturbative QCD approach
In this work, we calculate the branching ratios (BRs) and the polarization
fractions of sixty two charmless two-body meson decays into final states
involving one vector and one axial-vector meson () or two axial-vector
mesons() within the framework of perturbative QCD (pQCD) approach
systematically, where is either a or axial-vector meson.
All considered decay channels can only occur through the annihilation
topologies in the standard model. Based on the perturbative calculations and
phenomenological analysis, we find the following results: (i) the CP-averaged
BRs of the considered sixty two decays are in the range of to
; (ii) since the behavior for meson is much different from
that of meson, the BRs of decays are
generally larger than that of decays in the
pQCD approach; (iii) many considered decays modes, such as , , etc, have sizable BRs within the reach of the LHCb
experiments; (iv) the longitudinal polarization fractions of most considered
decays are large and play the dominant role; (v) the pQCD predictions for
several decays involving mixtures of and/or mesons are highly
sensitive to the values of the mixing angles, which will be tested by the
ongoing LHC and forthcoming Super-B experiments; (vi) the CP-violating
asymmetries of these considered decays are absent in the standard model
because only one type tree operator is involved.Comment: 31 pages, 1 figur
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