8,332 research outputs found
Heavy Flavours and CP Violation
Recent results on Heavy Flavours and CP violation are presented. After a
short introduction a taste of K and D results is given. In a third part results
on Vtd and Vts are summaryzed including BBbar mixing results and Bd radiative
decays. A summary of Vcb and Vub measurements is presented in the fourth part.
In the next section CP violation measurements in the Bd sector are shown.
Finally in the last part the overall status of the determination of the CKM
matrix is presented both in the context of the Standard Model and in the
context of New Physics.Comment: Plenary talk at HEP200
Overall determination of the CKM matrix
We discuss the problem of theoretical uncertainties in the combination of
observables related to the CKM matrix elements and propose a statistically
sensible method for combining them. The overall fit is performed on present
data, and constraints on the matrix elements are presented as well as on
fB*sqrt(Bb). We then explore the implications of recent measurements and
developments: jpsi-KS CP asymmetry, epsilon_prime/epsilon and B -> K pi
branching fractions. Finally, we extract from the overall fit the Standard
Model expectations for the rare kaon decays K -> pi nu anti-nu.Comment: Talk given at Heavy Flavours 8, Southampton, UK, 199
Feasibility study for a model independent measurement of 2 in decays using final states
In this paper we present a feasibility study for measuring the combination of
the Unitarity Triangle angle 2 with a time dependent Dalitz
analysis in decays using final states following the
method proposed in [1]. For this study we build a model for this decay using
the latest experimental information and we investigate the possibility of
fitting together with 2 all the relevant strong amplitudes and
phases of the decay model.
[1] R. Aleksan, T.C. Petersen and A. Soffer, Phys. Rev. D67 (2003) 096002
[hep-ph/0209194].Comment: 14 page
Search for new physics at LHCb: rare decays of B hadrons and CP violation in the charm sector
PoS(EPS-HEP 2009) 186 - On behalf of the LHCb collaborationInternational audienceLHCb is an heavy flavour precision experiment with LHC at CERN. It will search for New Physics in CP violation and rare decays in the heavy quarks sector. The experiment is ready to take data for the soon expected start-up of the LHC. An overview of its physics program in both the rare decays of B hadrons and CP violation in the charm sectors is given, illustrated by few key examples: measurements of the \bstomumu\ and \btokstmumu\ decay modes, study of the photon helicity using the \bstophig\ and \btokstee\ decay modes, as well as search for CP violation using D^0 meson
Renormalization of heavy-light currents in moving NRQCD
Heavy-light decays such as , and can be used to constrain the parameters of the Standard
Model and in indirect searches for new physics. While the precision of
experimental results has improved over the last years this has still to be
matched by equally precise theoretical predictions. The calculation of
heavy-light form factors is currently carried out in lattice QCD. Due to its
small Compton wavelength we discretize the heavy quark in an effective
non-relativistic theory. By formulating the theory in a moving frame of
reference discretization errors in the final state are reduced at large recoil.
Over the last years the formalism has been improved and tested extensively.
Systematic uncertainties are reduced by renormalizing the m(oving)NRQCD action
and heavy-light decay operators. The theory differs from QCD only for large
loop momenta at the order of the lattice cutoff and the calculation can be
carried out in perturbation theory as an expansion in the strong coupling
constant. In this paper we calculate the one loop corrections to the
heavy-light vector and tensor operator. Due to the complexity of the action the
generation of lattice Feynman rules is automated and loop integrals are solved
by the adaptive Monte Carlo integrator VEGAS. We discuss the infrared and
ultraviolet divergences in the loop integrals both in the continuum and on the
lattice. The light quarks are discretized in the ASQTad and highly improved
staggered quark (HISQ) action; the formalism is easily extended to other quark
actions.Comment: 24 pages, 11 figures. Published in Phys. Rev. D. Corrected a typo in
eqn. (51
Performances of Anode-resistive Micromegas for HL-LHC
Micromegas technology is a promising candidate to replace Atlas forward muon
chambers -tracking and trigger- for future HL-LHC upgrade of the experiment.
The increase on background and pile-up event probability requires detector
performances which are currently under studies in intensive RD activities.
We studied performances of four different resistive Micromegas detectors with
different read-out strip pitches. These chambers were tested using \sim120 GeV
momentum pions, at H6 CERN-SPS beam line in autumn 2010. For a strip pitch 500
micrometers we measure a resolution of \sim90 micrometers and a efficiency of
~98%. The track angle effect on the efficiency was also studied. Our results
show that resistive techniques induce no degradation on the efficiency or
resolution, with respect to the standard Micromegas. In some configuration the
resistive coating is able to reduce the discharge currents at least by a factor
of 100.Micromegas technology is a promising candidate to replace Atlas forward
muon chambers -tracking and trigger- for future HL-LHC upgrade of the
experiment. The increase on background and pile-up event probability requires
detector performances which are currently under studies in intensive RD
activities. We studied performances of four different resistive Micromegas
detectors with different read-out strip pitches. These chambers were tested
using \sim120 GeV momentum pions, at H6 CERN-SPS beam line in autumn 2010. For
a strip pitch 500 micrometers we measure a resolution of \sim90 micrometers and
a efficiency of \sim98%. The track angle effect on the efficiency was also
studied. Our results show that resistive techniques induce no degradation on
the efficiency or resolution, with respect to the standard Micromegas. In some
configuration the resistive coating is able to reduce the discharge currents at
least by a factor of 100.Comment: "Presented at the 2011 Hadron Collider Physics symposium (HCP-2011),
Paris, France, November 14-18 2011, 3 pages, 6 figures.
Angles from Decays with Charm
Proceedings of the CKM 2005 Workshop (WG5), UC San Diego, 15-18 March 2005.Comment: 62 pages, 55 figures. Proceedings of the CKM 2005 Workshop (WG5), UC
San Diego, 15-18 March 200
Aging studies of Micromegas prototypes for the HL-LHC
The micromegas technology is a promising candidate to replace the forward
muon chambers for the luminosity upgrade of ATLAS. The LHC accelerator
luminosity will be five times the nominal one, increasing background and
pile-up event probability. This requires detector performances which are
currently under study in intensive R&D activities. Aging is one of the key
issues for a high-luminosity LHC application. For this reason, we study the
properties of resistive micromegas detectors under intense X-ray radiation and
under thermal neutrons in different CEA-Saclay facilities. This study is
complementary to those already performed using fast neutrons.Comment: Proceedings of the MPGD2011 Conferenc
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Measurement of B(B-->X_s {\gamma}), the B-->X_s {\gamma} photon energy spectrum, and the direct CP asymmetry in B-->X_{s+d} {\gamma} decays
The photon spectrum in B --> X_s {\gamma} decay, where X_s is any strange
hadronic state, is studied using a data sample of (382.8\pm 4.2) \times 10^6
e^+ e^- --> \Upsilon(4S) --> BBbar events collected by the BABAR experiment at
the PEP-II collider. The spectrum is used to measure the branching fraction B(B
--> X_s \gamma) = (3.21 \pm 0.15 \pm 0.29 \pm 0.08)\times 10^{-4} and the
first, second, and third moments = 2.267 \pm 0.019 \pm 0.032 \pm
0.003 GeV,, )^2> = 0.0484 \pm 0.0053 \pm 0.0077 \pm
0.0005 GeV^2, and )^3> = -0.0048 \pm 0.0011 \pm 0.0011
\pm 0.0004 GeV^3, for the range E_\gamma > 1.8 GeV, where E_{\gamma} is the
photon energy in the B-meson rest frame. Results are also presented for
narrower E_{\gamma} ranges. In addition, the direct CP asymmetry A_{CP}(B -->
X_{s+d} \gamma) is measured to be 0.057 \pm 0.063. The spectrum itself is also
unfolded to the B-meson rest frame; that is the frame in which theoretical
predictions for its shape are made.Comment: 37 pages, 19 postscript figures, submitted to Phys. Rev. D. No
analysis or results have changed from previous version. Some changes to
improve clarity based on interactions with Phys. Rev. D referees, including
one new Figure (Fig. 13), and some minor wording/punctuation/spelling
mistakes fixe
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