CERN Accelerating science

Combined particle identification of TPC-TOF shown as a two dimensional plot. The PID signals are expressed in terms of the deviation from the expected response for pions in each detector.

Combined particle identification in the TPC and TOF for data from \PbPb collisions at $\sqrtsNN=2.76\,\TeV$, shown as a two-dimensional plot. The PID signals are expressed in terms of the deviation from the expected response for pions in each detector.

An example of the iterative prior extraction procedure for \pPb data (for the 10--20\% V0A multiplicity class). The extracted K$/\pi$ ratio of the priors is shown as a function of \pT at each step of the iteration (left) and as a ratio of the value between each successive step (right). Step 0 refers to the initial ratio, which is set to 1.

An example of the iterative prior extraction procedure for \pPb data (for the 10--20\% V0A multiplicity class). The extracted K$/\pi$ ratio of the priors is shown as a function of \pT at each step of the iteration (left) and as a ratio of the value between each successive step (right). Step 0 refers to the initial ratio, which is set to 1.

The proton/pion ratio (left) and kaon/pion ratio (right), as measured by ALICE~\cite{spectra7TeV,spectraPbPb} using TPC and TOF (filled symbols), compared with the standard priors as described in the text (open symbols) for \PbPb and \pp collisions. For \PbPb, the results are reported for different centrality classes. These particle ratios are calculated for $| \Delta y|<0.5$. The double ratios (the measured abundances divided by the Bayesian priors) are shown in the lower panels.

The proton/pion ratio (left) and kaon/pion ratio (right), as measured by ALICE~\cite{spectra7TeV,spectraPbPb} using TPC and TOF (filled symbols), compared with the standard priors as described in the text (open symbols) for \PbPb and \pp collisions. For \PbPb, the results are reported for different centrality classes. Particle ratios are calculated for mid-rapidity, $|y|<0.5$. The double ratios (the measured abundances divided by the Bayesian priors) are shown in the lower panels.

The proton/pion ratio (left) and kaon/pion ratio (right), as measured by ALICE ~\cite{spectrapPb} using TPC and TOF (filled symbols), compared with the standard priors obtained with an iterative procedure (open symbols) for \pPb~collisions for different V0A multiplicity classes. Particle ratios are calculated for $| \Delta y|<0.5$. The double ratios (the measured abundances divided by the Bayesian priors) are shown in the lower panels.

The proton/pion ratio (left) and kaon/pion ratio (right), as measured by ALICE ~\cite{spectrapPb} using TPC and TOF (filled symbols), compared with the standard priors obtained with an iterative procedure (open symbols) for \pPb~collisions for different V0A multiplicity classes. Particle ratios are calculated for mid-rapidity, $|y|<0.5$ with respect to the centre-of-mass system. The double ratios (the measured abundances divided by the Bayesian priors) are shown in the lower panels.

$\Vzero$ fits to extract the yield and background for $\Kzs \to \piMinus\piPlus$ in \pPb collisions at $\sqrtsNN=5.02$\,TeV. From left to right: no PID selections applied and selecting pions, kaons and protons using a specific PID strategy (here, Bayesian probability $>$ 0.2). The yield estimated from the second plot from the left (compared with the no-PID yield result) gives a measure of the PID efficiency for the pions, while the remaining ones give information about misidentification.

$\Vzero$ fits to extract the yield and background for $\Kzs \to \piMinus\piPlus$ in \pPb collisions at $\sqrtsNN=5.02$\,TeV. From left to right: no PID selections applied and selecting pions, kaons and protons using a specific PID strategy (here, Bayesian probability $>$ 0.2). The yield estimated from the second plot from the left (compared with the no-PID yield result) gives a measure of the PID efficiency for the pions, while the remaining ones give information about misidentification.

\pid matrix elements in \pPb collisions after selection with a Bayesian probability greater than 80\%. Comparisons with Monte Carlo (open symbols) are also shown.

\pid matrix elements in \pPb collisions after selection with a Bayesian probability greater than 80\%. Comparisons with Monte Carlo (open symbols) are also shown.

\pid matrix elements in \pPb collisions after selection with a 2$\sigma$ selection on the combined TPC and TOF signal. Comparisons with Monte Carlo (open symbols) are also shown.

\pid matrix elements in \pPb collisions after selection with a 2$\sigma$ selection on the combined TPC and TOF signal. Comparisons with Monte Carlo (open symbols) are also shown.

Data/Monte Carlo ratios of PID efficiencies for pions, kaons and protons in \pPb collisions, extracted using different Bayesian probability thresholds.

Data/Monte Carlo ratios of PID efficiencies for pions, kaons and protons in \pPb collisions, extracted using different Bayesian probability thresholds.

Data/Monte Carlo ratios of PID efficiencies for pions, kaons and protons in \pPb collisions, extracted using 2- and 3$\sigma$ selections on the combined TPC and TOF signal.

Data/Monte Carlo ratios of PID efficiencies for pions, kaons and protons in \pPb collisions, extracted using 2- and 3$\sigma$ selections on the combined TPC and TOF signal.

Identified particle spectra from the Bayesian analysis, compared with the measurement reported by ALICE in pp collisions at 7\,\TeV~\cite{spectra7TeV}.

Identified particle spectra from the Bayesian analysis, compared with the measurement reported by ALICE in pp collisions at 7\,\TeV~\cite{spectra7TeV}.

A comparison of the invariant mass distributions in three $\pt$ intervals for \Dzero candidates obtained without PID, with \nsigma PID, and with Bayesian PID using the maximum probability condition. Due to the low statistical significance, it was not possible to extract a stable signal without PID for $1<\pt<2\,\GeVc$, therefore this fit and its results are not shown.

A comparison of the invariant mass distributions in three $\pt$ intervals for \Dzero candidates obtained without PID, with \nsigma PID, and with Bayesian PID using the maximum probability condition. Due to the low statistical significance, it was not possible to extract a stable signal without PID for $1<\pt<2\,\GeVc$, therefore this fit and its results are not shown.

(Left) Signal-to-background ratio and (right) statistical significance as a function of $\pt$ for various methods of particle identification. Note that the increase in significance at $8 < \pt < 12 \mathrm{\,\gevc}$ is an effect of the width of the $\pt$ interval increasing from 1 to 4\,\gevc.

(Left) Signal-to-background ratio and (right) statistical significance as a function of $\pt$ for various methods of particle identification. Note that the increase in significance at $8 < \pt < 12\,\gevc$ is an effect of the width of the $\pt$ interval increasing from 1 to 4\,\gevc.

(Left) Signal-to-background ratio and (right) statistical significance as a function of $\pt$ for various methods of particle identification. Note that the increase in significance at $8 < \pt < 12 \mathrm{\,\gevc}$ is an effect of the width of the $\pt$ interval increasing from 1 to 4\,\gevc.

(Left) Signal-to-background ratio and (right) statistical significance as a function of $\pt$ for various methods of particle identification. Note that the increase in significance at $8 < \pt < 12\,\gevc$ is an effect of the width of the $\pt$ interval increasing from 1 to 4\,\gevc.

A comparison of the PID efficiencies for $\DtoKpi$ obtained using various PID strategies, as a function of $\pt$.

A comparison of the PID efficiencies for $\DtoKpi$ obtained using various PID strategies, as a function of $\pt$.

Ratios of corrected yields obtained using various Bayesian PID methods to that obtained using \nsigma PID, for (left) fixed probability thresholds, and (right) maximum probability and weighted Bayesian PID, and no PID. The 5\% systematic uncertainty on the \nsigma PID method is shown as a blue box at $0.5\,\GeVc$.

Ratios of corrected yields obtained using various Bayesian PID methods to that obtained using \nsigma PID, for (left) fixed probability thresholds, and (right) maximum probability and weighted Bayesian PID, and no PID. The 5\% systematic uncertainty on the \nsigma PID method is shown as a blue box at $0.5\,\GeVc$.

Ratios of corrected yields obtained using various Bayesian PID methods to that obtained using \nsigma PID, for (left) fixed probability thresholds, and (right) maximum probability and weighted Bayesian PID, and no PID. The 5\% systematic uncertainty on the \nsigma PID method is shown as a blue box at $0.5\,\GeVc$.

Ratios of corrected yields obtained using various Bayesian PID methods to that obtained using \nsigma PID, for (left) fixed probability thresholds, and (right) maximum probability and weighted Bayesian PID, and no PID. The 5\% systematic uncertainty on the \nsigma PID method is shown as a blue box at $0.5\,\GeVc$.

Invariant mass spectra of $\LctopKpi$ using \nsigma PID, minimum-$\sigma$ PID and Bayesian PID for (left) $2<\pt<6$\,\gevc and (right) $3<\pt<4$\,\gevc. Due to the low statistical significance, it was not possible to extract a stable signal for \nsigma PID for $3<\pt<4\,\GeVc$, therefore this fit and its results are not shown.

Invariant mass spectra of $\LctopKpi$ using \nsigma PID, minimum-$\sigma$ PID and Bayesian PID for (left) $2<\pt<6$\,\gevc and (right) $3<\pt<4$\,\gevc. Due to the low statistical significance, it was not possible to extract a stable signal for \nsigma PID for $3<\pt<4\,\GeVc$, therefore this fit and its results are not shown.