# Posters

Senast inlagda poster:
2017-02-27
15:51
The new strategy for particle identification samples in Run 2 at LHCb
 Reference: Poster-2017-576 Created: 2017. -1 p Creator(s): Mathad, Abhijit For Run 2 of LHCb data taking, the selection of PID calibration samples is implemented in the high level trigger. A further processing is needed to provide background-subtracted samples to determine the PID performance, or to develop new algorithms for the evaluation of the detector performance in upgrade scenarios. This is achieved through a centralised production which makes efficient use of LHCb computing resources. This poster presents the major steps of the implementation. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-02-27
15:44
Measurement of $b-$hadron production asymmetries in 7 and 8 TeV $pp$ collisions at LHCb
 Reference: Poster-2017-575 Created: 2017. -1 p Creator(s): Ferrari, Fabio The $B^0$, $B^0_s$, $B^+$ and $\Lambda^0_b$ hadron production asymmetries are measured using a data sample corresponding to an integrated luminosity of 3.0 fb$^{-1}$, collected by the LHCb experiment in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The measurements are performed as a function of transverse momentum and rapidity of the $b$ hadrons within the LHCb detector acceptance. The overall production asymmetries, integrated over transverse momentum and rapidity, are also determined. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-02-27
15:33
Observation of the decay $B^0_s \to \eta_c \phi$ and evidence for $B^0_s \to \eta_c \pi^+ \pi^-$ at LHCb
 Reference: Poster-2017-574 Created: 2017. -1 p Creator(s): Martin, Morgan Leni A study of $B^0_s \to \eta_c \phi$ and $B^0_s \to \eta_c \pi^+ \pi^-$ decays is performed using $pp$ collision data corresponding to an integrated luminosity of 3.0 fb, collected with the LHCb detector in Run 1 of the LHC. The observation of the decay $B^0_s \to \eta_c \phi$ is reported, where the $\eta_c$ meson is reconstructed in the $p\bar p$, $K^+K^-\pi^+\pi^-$, $\pi^+\pi^-\pi^+\pi^-$ and $K^+K^-K^+K^-$ decay modes and the $\phi(1020)$ in the $K^+ K^-$ decay mode. The decay $B^0_s \to J/\psi \phi$ is used as a normalisation channel. Evidence is also reported for the decay $B^0_s \to \eta_c \pi^+\pi^-$, where the $\eta_c$ meson is reconstructed in the $p\bar p$ decay mode, using the decay $B^0_s \to J/\psi \pi^+ \pi^-$ as a normalisation channel. The measured branching fractions are \begin{eqnarray*} {\mathcal B (B^{0}_{s} \to \eta_{c} \phi)} &=& \left(5.01 \pm 0.53 \pm 0.27 \pm 0.63 \right) \times 10^{-4} \,, \nonumber \\ {\mathcal B (B^{0}_{s} \to \eta_{c} \pi^+ \pi^-)} &=& \left(1.76 \pm 0.59 \pm 0.12 \pm 0.29 \right) \times 10^{-4} \,, \end{eqnarray*} where in each case the first uncertainty is statistical, the second systematic and the third uncertainty is due to the limited knowledge of the external branching fractions. Related links:LHCC Poster Session © CERN Geneva Access to file

2017-02-27
14:58
Measurement of the photon polarization in radiative $B^0_s$ decays at LHCb
 Reference: Poster-2017-573 Created: 2017. -1 p Creator(s): Sanchez Mayordomo, Carlos The photon polarization is studied for the first time in $B_s^0$ decays, using an integrated luminosity of 3 fb$^{-1}$ of proton-proton data recorded by the LHCb experiment. An untagged time-dependent analysis of $B_s^0 \rightarrow \phi\gamma$ decays allows to measure the CPV parameter $\mathcal{A}^{\Delta}$, which is sensitive to the left- and right-handed helicity amplitudes. The measured value $\mathcal{A}^{\Delta} = -0.98 \; ^{+0.46}_{-0.52}\text{(stat.)} ^{+0.23}_{-0.20}\text{(syst.)}$ is consistent with the Standard Model prediction within two standard deviations. This value can put constraints on the Wilson coefficients $\mathcal{C}_7$ and $\mathcal{C}_7^{'}$. With a tagged analysis of the same decay the parameter $S_{\phi\gamma}$, also sensitive to the photon polarization, could be measured. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-02-27
14:53
Search for $C\!P$ violation in $\Lambda^0_b \to p K^- \mu^+ \mu^-$ decays at LHCb
 Reference: Poster-2017-572 Created: 2017. -1 p Creator(s): Marangotto, Daniele A search for $C\!P$ violation in the rare decay $\Lambda^0_b \to p K^- \mu^+ \mu^-$ is presented. This decay is mediated by flavour-changing neutral-current transitions in the Standard Model and is potentially sensitive to new sources of $C\!P$ violation. The study is based on a data sample of proton-proton collisions recorded with the LHCb experiment, corresponding to an integrated luminosity of $3\mathrm{fb}^{-1}$. Two observables that are sensitive to different manifestations of $C\!P$ violation are measured, $\Delta\mathcal{A}_{C\!P} \equiv \mathcal{A}_{C\!P}(\Lambda^0_b \to p K^- \mu^+ \mu^-)-\mathcal{A}_{C\!P}(\Lambda^0_b\to pK^- J/\psi)$ and $a_{C\!P}^{\widehat{T}_{\mathrm{odd}}}$, where the latter is based on asymmetries in the angle between the $\mu^+\mu^-$ and $p K^-$ decay planes. No evidence for $C\!P$ violation is found. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-02-27
14:47
$CP$-violating lifetime asymmetries of prompt two-body charm decays at LHCb
 Reference: Poster-2017-571 Created: 2017. -1 p Creator(s): Maguire, Kevin Scott Asymmetries in the time-dependent rates of ${D}^{0} \rightarrow {K}^{+} {K}^{-}$ and ${D}^{0} \rightarrow \mathrm{\pi}^{+} \mathrm{\pi}^{-}$ decays are measured in a $pp$ collision data sample collected by the $\mbox{LHCb}$ detector during $\mbox{LHC}$ Run 1, corresponding to an integrated luminosity of $3{\,fb}^{-1}$. The asymmetries in effective decay widths between ${D}^{0}$ and ${\kern 0.2em\overline{\kern -0.2em D}{}}{}^{0}$ decays, sensitive to indirect $CP$ violation, are measured to be $A_{\Gamma} ({K}^{+} {K}^{-}) = (-0.30 \pm 0.32 \pm 0.10)\times 10^{-3}$ and $A_{\Gamma}(\mathrm{\pi}^{+} \mathrm{\pi}^{-}) = (0.46 \pm 0.58 \pm 0.12)\times 10^{-3}$, where the first uncertainty is statistical, and the second systematic. These measurements show no evidence of CP violation and improve on the precision of the previous best measurements by nearly a factor of two. Related links:LHCC poster session © CERN Geneva Access to files

2017-02-27
12:28
LHCb cross-section measurements with heavy flavour jets
 Reference: Poster-2017-570 Created: 2017. -1 p Creator(s): Michielin, Emanuele Cross-section measurements of jets originating from the hadronization of beauty ($b$) and charm ($c$) quarks at LHCb give the unique opportunity to probe Parton Distribution Functions (PDFs) at low and large momentum fraction and to test the Standard Model in the forward region. In this poster the production of $t\bar{t}$ pairs in the forward region, the measurement of the $W+b\bar{b}$ and $W+c\bar{c}$ cross-section and the measurement of the $Z\rightarrow b\bar{b}$ cross-section are presented. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-02-24
11:44