3,283 research outputs found
Dispersion approach to quark-binding effects in weak decays of heavy mesons
Dispersion approach based on the constituent quark picture and its
applications to weak decays of heavy mesons are reviewed. Meson interaction
amplitudes are represented within this approach as relativistic spectral
integrals over the mass variables in terms of the meson wave functions and
spectral densities of the corresponding Feynman diagrams. Various applications
of this approach are discussed:
Relativistic spectral representations for meson elastic and transition form
factors at spacelike momentum transfers are constructed. Form factors at
are obtained by the analytical continuation. As a result of this
procedure, form factors are given in the full range of the weak decay in
terms of the wave functions of the participating mesons.
The 1/m_Q expansion of the obtained spectral representations for the form
factors for the particular limits of the heavy-to-heavy and heavy-to-light
transitions are analysed. Their full consistency with the constraints provided
by long-distance QCD for these limits is demonstrated. Predictions for form
factors for B, B(s), D, and D(s) decays to light mesons are given. The
B\to\gamma l\nu decay and the weak annihilation in rare radiative decays are
considered. Nonfactorizable corrections to the B^0-\bar B^0 mixing are
calculated. Inclusive weak B-decays are analysed and the differential
distributions are obtained in terms of the B-meson wave function.Comment: revtex, 119 pages. Summary of changes made: In Sect. V comparison
with the recent experimental data is added, in Sect. VI discussion of contact
terms in B->V\gamma is extended and comments on the recent publications are
given, in Sect. VII signs of the decay constants are brought in agreement
with other Sections, typoes correcte
Performance of <i>b</i>-Jet identification in the ATLAS experiment
The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty
Performance of b-jet identification in the ATLAS experiment
The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty.La lista completa de autores que integran el documento puede consultarse en el archivo.Instituto de FÃsica La Plat
Performance of b-jet identification in the ATLAS experiment
The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty.La lista completa de autores que integran el documento puede consultarse en el archivo.Instituto de FÃsica La Plat
Status and Prospects of Top-Quark Physics
The top quark is the heaviest elementary particle observed to date. Its large
mass of about 173 GeV/c^2 makes the top quark act differently than other
elementary fermions, as it decays before it hadronises, passing its spin
information on to its decay products. In addition, the top quark plays an
important role in higher-order loop corrections to standard model processes,
which makes the top quark mass a crucial parameter for precision tests of the
electroweak theory. The top quark is also a powerful probe for new phenomena
beyond the standard model. During the time of discovery at the Tevatron in 1995
only a few properties of the top quark could be measured. In recent years,
since the start of Tevatron Run II, the field of top-quark physics has changed
and entered a precision era. This report summarises the latest measurements and
studies of top-quark properties and gives prospects for future measurements at
the Large Hadron Collider (LHC).Comment: 76 pages, 35 figures, submitted to Progress in Particle and Nuclear
Physic
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