3,220 research outputs found
Heavy Flavour Working Group Summary
We review theoretical and phenomenological aspects of heavy flavour
production as discussed in the heavy flavour working group of the DIS 2012.
Recent theoretical progress includes approximate NNLO calculations for heavy
quark structure functions in deep inelastic scattering, the extension of the
ACOT heavy flavour scheme to jet production, and advances in top physics where
the highlight is clearly the first complete NNLO QCD prediction for top pair
production in the annihilation channel. Furthermore, state of the
art phenomenological predictions for open charm and bottom, charmonium, and
single top and top pair production are discussed in addition to other topics
such as the effect of double parton scattering on heavy quark production. New
measurements on charm and beauty production presented in the heavy flavor
working group are summarized and discussed in comparison with QCD predictions.
Top quark strong and weak couplings as well as top quark properties are being
measured with precision at the LHC and the Tevatron. We summarize also recent
results on spectroscopy of charmonia, bottomonia and -hadrons, along with
studies of their decays and properties. Searches for physics beyond Standard
Model through precise measurements of rare decays of heavy flavours are
discussed as well.Comment: 16 pages, 5 figures, to be published in the Proceedings of the XX
International Workshop on Deep Inelastic Scattering, University of Bonn,
26-30th March 201
On model-independent searches for direct CP violation in multi-body decays
Techniques for performing model-independent searches for direct CP violation
in three and four-body decays are discussed. Comments on the performance and
the optimisation of a binned chisquare approach and an unbinned approach, known
as the energy test, are made. The use of the energy test in the presence of
background is also studied. The selection and treatment of the coordinates used
to describe the phase-space of the decay are discussed. The conventional
model-independent techniques, which test for P-even CP violation, are modified
to create a new approach for testing for P-odd CP violation. An implementation
of the energy test using GPUs is described
Charged charmonium-like states as rescattering effects in B -> D_sJ D^(*) decays
Using purely phenomenological approach we show that the peaking structures
observed in the psi(2S) pi+ and chi_c1 pi+ mass spectra in B -> psi(2S)(chi_c1)
pi+ K decays can be result of (D \bar{D}^(*))+ -> (ccbar)_res pi+ rescattering
in the decays B -> D_sJ (-> \bar{D}(*) K) D(*). In particular, the position of
the peak in the chain B -> D_s(2S) D+ -> K- \bar{D}*0 D+ -> K- psi(2S) pi+
coincides well with the measured Z(4430) mass, assuming the mass of D_s(2S)
(the first radial excitation of D_s) to be 2610 MeV/c2. The widths of the
Z(4430) peak is also well reproduced in this approach independent on the width
of D_s(2S). Although the decay B -> D_s(2S) D+ has not been observed so far and
even D_s(2S)-meson is not discovered yet, this decay is expected to be large,
and the mass of D_s(2S) is predicted in the range (2600-2650)MeV/c2. The broad
bump in chi_c1 pi+ spectrum can be attributed to the B -> D_s*(2S) D+ -> K-
\bar{D}0 D+ decay observed with a large branching fraction followed by
rescattering \bar{D}0 D^+ -> chi_c1 pi+.Comment: 4 pages, 3 figure
Spectral Correlation in Incommensurate Multi-Walled Carbon Nanotubes
We investigate the energy spectra of clean incommensurate double-walled
carbon nanotubes, and find that the overall spectral properties are described
by the so-called critical statistics of Anderson metal-insulator transition. In
the energy spectra, there exist three different regimes characterized by
Wigner-Dyson, Poisson, and semi-Poisson distributions. This feature implies
that the electron transport in incommensurate multi-walled nanotubes can be
either diffusive, ballistic, or intermediate between them, depending on the
position of the Fermi energy.Comment: final version to appear in Phys. Rev. Let
Evidence for CP Violation in B0 -> D+D- Decays
We report measurements of the branching fraction and CP violation parameters
in B0 -> D+D- decays. The results are based on a data sample that contains 535
x 10^6 BBbar pairs collected at the Upsilon(4S) resonance, with the Belle
detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97 +- 0.20
(stat) +- 0.20 (syst)] x 10^(-4) for the branching fraction of B0 -> D+D-. The
measured values of the CP violation parameters are: S = -1.13 +- 0.37 +- 0.09,
A = 0.91 +- 0.23 +- 0.06, where the first error is statistical and the second
is systematic. We find evidence of CP violation in B0 -> D+D- at the 4.1 sigma
confidence level. While the value of S is consistent with expectations from
other measurements, the value of the parameter A favors large direct CP
violation at the 3.2 sigma confidence level, in contradiction to Standard Model
expectations.Comment: 12 pages, 3 figures, submitted to PR
Study of the Baryon-Antibaryon Low-Mass Enhancements in Charmless Three-body Baryonic B Decays
The angular distributions of the baryon-antibaryon low-mass enhancements seen
in the charmless three-body baryonic B decays B+ -> p pbar K+, B0 -> p pbar Ks,
and B0 -> p Lambdabar pi- are reported. A quark fragmentation interpretation is
supported, while the gluonic resonance picture is disfavored. Searches for the
Theta+ and Theta++ pentaquarks in the relevant decay modes and possible
glueball states G with 2.2 GeV/c2 < M-ppbar < 2.4 GeV/c2 in the ppbar systems
give null results. We set upper limits on the products of branching fractions,
B(B0 -> Theta+ p)\times B(Theta+ -> p Ks) Theta++
pbar) \times B(Theta++ -> p K+) G K+) \times
B(G -> p pbar) < 4.1 \times 10^{-7} at the 90% confidence level. The analysis
is based on a 140 fb^{-1} data sample recorded on the Upsilon(4S) resonance
with the Belle detector at the KEKB asymmetric-energy e+e- collider.Comment: 14 pages, 13 figure files, update of hep-ex/0409010 for journal
submisssio
The newly observed open-charm states in quark model
Comparing the measured properties of the newly observed open-charm states
D(2550), D(2600), D(2750), D(2760), D_{s1}(2710), D_{sJ}(2860), and
D_{sJ}(3040) with our predicted spectroscopy and strong decays in a constituent
quark model, we find that: (1) the D(2\,^1S_0) assignment to D(2550) remains
open for its too broad width determined by experiment; (2) the D(2600) and
can be identified as the 2\,^3S_1-1\,^3D_1 mixtures; (3) if
the D(2760) and D(2750) are indeed the same resonance, they would be the
D(1\,^3D_3); otherwise, they could be assigned as the D(1\,^3D_3) and
, respectively; (4) the could be either the
's partner or the D_s(1\,^3D_3); and (5) both the
and interpretations for the seem likely. The
and radiative decays of these sates are also studied. Further
experimental efforts are needed to test the present quarkonium assignments for
these new open-charm states.Comment: 26 pages,7 figures, journal versio
Recommended from our members
Search for lepton-flavour-violating decays of Higgs-like bosons.
A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV , collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1 . The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/c2 to 4 pb for a mass of 195 GeV/c2
- …