1,439,988 research outputs found
Mixing and indirect violation in charm mesons at LHCb
No full textThe LHCb experiment has collected the world's largest sample of charmed hadrons. This sample is used to measure - mixing and to search for violation. New measurements of the mixing and -violating parameters , , and are presented
Model-independent measurement of charm mixing parameters in D0 -> K0S pi+ pi- decays
No full textThis thesis presents a measurement of charm mixing and CP-violation parameters using D0 -> K0S pi+ pi- decays. These mixing parameters include the mass and decay-width differences of the mass eigenstates of the D0-D0bar system. A search for Charge-Parity violation is performed through measurements of D0-D0b mixing and of the interference between mixing and decay amplitudes. The dataset consists of events reconstructed in proton-proton collisions collected by the LHCb experiment during the
operation of the Large Hadron Collider (LHC) from 2016 to 2018. This sample corresponds to an integrated luminosity of 5.4 fb^-1. The D0 decays are selected in semileptonically decays of b hadrons. The results are expressed in terms of the CP-averaged mixing parameters and CP-violating differences as
x_cp= (+4.29 +/- 1.48 (stat) +/- 0.26 (syst)) x 10^{-3}
y_cp= (+12.61 +/- 3.12 (stat) +/- 0.83 (syst)) x 10^{-3}
delta x= (-0.77 +/- 0.93 (stat) +/- 0.28 (syst)) x 10^{-3}
delta y= (+3.01 +/- 1.92 (stat) +/- 0.26 (syst)) x 10^{-3}
where the first uncertainty is statistical and the second is systematic. They correspond to the mixing and CP-violation parameters
x = 0.46^{+0.15}_{-0.16} x 10^{-2}
y = 1.24^{+0.32}_{-0.33} x 10^{-2}
|q/p| = 1.21^{+0.21}_{-0.15}
\phi = -0.132^{+0.088}_{-0.120} rad.
The value of x deviates from zero with a significance of almost 3 sigma.
These results are complementary to and consistent with previous measurements and with the current world-average values.
They represent an independent and complementary knowledge of the charm-mixing parameters.
A combination with the recent LHCb analysis of Dstar -> D0 (->K0S pi+ pi-) pi decays is also reported.LPHE
Model-independent measurement of charm mixing parameters in decays
No full textThis thesis presents a measurement of charm mixing and CP-violation parameters using decays. These mixing parameters include the mass and decay-width differences of the mass eigenstates of the - system. A search for Charge-Parity violation is performed through measurements of - mixing and of the interference between mixing and decay amplitudes. The dataset consists of events reconstructed in collisions collected by the LHCb experiment during the operation of the Large Hadron Collider (LHC) from 2016 to 2018. This sample corresponds to an integrated luminosity of 5.4 fb. The decays are selected in semileptonically decays of hadrons. The results are expressed in terms of the CP-averaged mixing parameters and CP-violating differences as \begin{align*} x_{\rm CP} &= [ \,\,\,\,\,4.29 \pm 1.48 \mbox{(stat)} \pm 0.26 \mbox{(syst)} ] \times 10^{-3}\,,\\ y_{\rm CP} &= [ \,\,12.61 \pm 3.12 \mbox{(stat)} \pm 0.83 \mbox{(syst)} ] \times 10^{-3} \,,\\ \Delta x \,\, &= [ \,-0.77 \pm 0.93 \mbox{(stat)} \pm 0.28 \mbox{(syst)} ] \times 10^{-3} \,,\\ \Delta y \, &= [ \,\,\,\,\,3.01 \pm 1.92 \mbox{(stat)} \pm 0.26 \mbox{(syst)} ] \times 10^{-3} \,. \end{align*} where the first uncertainty is statistical and the second is systematic. They correspond to the mixing and CP-violation parameters \begin{align*} x &= 0.46^{+0.15}_{-0.16}\times10^{-2} \,, \\ y &= 1.24^{+0.32}_{-0.33}\times10^{-2} \,, \\ |q/p| &= 1.21^{+0.21}_{-0.15} \,,\\ \phi &= -0.132^{+0.088}_{-0.120} \, \mbox{rad}. \end{align*} The value of deviates from zero with a significance of almost 3. These results are complementary to and consistent with previous measurements and with the current world-average values. They represent an independent and complementary knowledge of the charm-mixing parameters. A combination with the recent LHCb analysis of decays is also reported
Charm Physics at LHCb
No full textWe review four most precise measurements from charm physics program at the LHCb during 2021. These include the first observation of non-zero mass difference between neutral charm-meson eigenstates, the world most precise determination of both time-dependent and time-integrated charge-parity.LPH
Charm Physics at LHCb
No full textWe review four most precise measurements from charm physics program at the LHCb during 2021. These include the first observation of non-zero mass difference between neutral charm-meson eigenstates, the world most precise determination of both time-dependent and time-integrated charge-parity
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mapping the Discipline of the Olympic Games An Author-Cocitation Analysis
No full textThe authors conducted an author cocitation analysis on prominent authors writing about the Olympics during the 1990s. Author cocitation is an established bibliometric technique that can be used to measure the relative similarities of topics written about by the cited authors. This enables a visual representation of the “intellectual space” of the discipline, in this case the Olympics, to be created for the period under review. So core and peripheral research areas are identified, along with their major contributors. The representation appears as a two-dimensional cluster-enhanced map. Subject expertise was then applied to the results to place labels on the generated clusters of authors and their topics
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