Are you an EPFL student looking for a semester project?

Work with us on data science and visualisation projects, and deploy your project as an app on top of GraphSearch.

Publication

Updated measurement of time-dependent CP-violating observables in B-s(0) -> J/psi K+K- decays

Jian Wang, Olivier Schneider, Yiming Li, Yi Zhang, Aurelio Bay, Guido Haefeli, Christoph Frei, Frédéric Blanc, Tatsuya Nakada, Michel De Cian, Luca Pescatore, François Fleuret, Elena Graverini, Chitsanu Khurewathanakul, Renato Quagliani, Federico Betti, Andrea Merli, Aravindhan Venkateswaran, Vitalii Lisovskyi, Sebastian Schulte, Veronica Sølund Kirsebom, Elisabeth Maria Niel, Mingkui Wang, Zhirui Xu, Lei Zhang, Ho Ling Li, Mark Tobin, Minh Tâm Tran, Niko Neufeld, Matthew Needham, Marc-Olivier Bettler, Greig Alan Cowan, Maurizio Martinelli, Vladislav Balagura, Donal Patrick Hill, Liang Sun, Pietro Marino, Mirco Dorigo, Xiaoxue Han, Liupan An, Federico Leo Redi, Plamen Hristov Hopchev, Thibaud Humair, Maxime Schubiger, Hang Yin, Guido Andreassi, Violaine Bellée, Olivier Göran Girard, Axel Kuonen, Preema Rennee Pais, Pavol Stefko, Tara Nanut, Maria Elena Stramaglia, Yao Zhou, Tommaso Colombo, Vladimir Macko, Guillaume Max Pietrzyk, Evgenii Shmanin, Simone Meloni, Xiaoqing Zhou, Surapat Ek-In, Dipanwita Dutta, Zheng Wang, Yi Wang, Hans Dijkstra, Gerhard Raven, Peter Clarke, Frédéric Teubert, Giovanni Carboni, Victor Coco, Adam Davis, Paolo Durante, Wenyu Zhang, Yu Zheng, Anton Petrov, Maxim Borisyak, Feng Jiang, Chen Chen, Zhipeng Tang, Xuan Li, Alexey Boldyrev, Almagul Kondybayeva, Hossein Afsharnia
2019
Journal paper

Abstract

The decay-time-dependent CP asymmetry in B0 s. J/. K + K-decays is measured using proton-proton collision data, corresponding to an integrated luminosity of 1.9 fb-1, collected with the LHCb detector at a centre-ofmass energy of 13 TeV in 2015 and 2016. Using a sample of approximately 117 000 signal decays with an invariant K + K-mass in the vicinity of the f( 1020) resonance, the CP-violating phase fs is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the B0 s-B0s system, s. The difference of the average B0 s and B0 meson decay widths, s-d, is determined using in addition a sample of B0. J/. K + p-decays. The values obtained are fs =-0.083 +/- 0.041 +/- 0.006 rad, s = 0.077 +/- 0.008 +/- 0.003 ps-1 and s-d = -0.0041 +/- 0.0024 +/- 0.0015 ps-1, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of these quantities to date and are consistent with expectations based on the Standard Model and with a previous LHCb analysis of this decay using data recorded at centre-of-mass energies 7 and 8 TeV. Finally, the results are combined with recent results from B0 s. J/. p + p-decays obtained using the same dataset as this analysis, and with previous independent LHCb results.

Official source

https://infoscience.epfl.ch/record/270287?ln=en

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Model-independent measurement of charm mixing parameters in D0 -> K0S pi+ pi- decays

Surapat Ek-In

This 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 theoperation 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 asx_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.

EPFL2022

Precision measurement of neutral charm meson mixing parameters

Guillaume Max Pietrzyk

This thesis presents a measurement of the neutral charm meson mixing parameters

y_{C\!P}^{KK} - y_{C\!P}^{K\pi}

and

y_{C\!P}^{\pi\pi} - y_{C\!P}^{K\pi}

using

D^0 \rightarrow K^-K^+

D^0 \rightarrow \pi^-\pi^+

and

D^0 \rightarrow K^-\pi^+

decays. These parameters correspond to the departure from unity of the ratio of the effective decay widths of

D^0 \rightarrow K^-K^+

D^0 \rightarrow \pi^-\pi^+

decays over the effective decay width of

D^0 \rightarrow K^-\pi^+

decays. \The measurement is done with the dataset collected in the Run 2 (2015-2018) of the Large Hadron Collider (LHC) by the LHCb experiment at CERN at a centre-of-mass energy of

13 \tev

, and corresponding to an integrated luminosity of

6 \, \mathrm{fb}^{-1}

. The

D^0

mesons originate from

D^{\ast+}(2010) \rightarrow D^0 \pi^+

decays. We measure \begin{equation} \begin{split} y_{C!P}^{KK} - y_{C!P}^{K\pi} & = (7.08 \pm 0.30 \pm 0.14) \times 10^{-3}, , \ y_{C!P}^{\pi\pi} - y_{C!P}^{K\pi} & = (6.57 \pm 0.53 \pm 0.16) \times 10^{-3}, , \end{split}\end{equation}where the first uncertainty is statistical while the second is systematic. Neglecting final state dependent contributions, we obtain the combination\begin{equation} y_{C!P} - y_{C!P}^{K\pi} = (6.96 \pm 0.26 \pm 0.13) \times 10^{-3} , .\end{equation}This measurement improves by a factor of four the precision of the current world average value of

y_{C\!P} - y_{C\!P}^{K\pi}

. In addition, the results allow for an improvement of the precision on the mixing parameter

y

by a factor of two, where

y

is connected to the width difference between the neutral charm meson mass eigenstates. The new world average value of

y

is estimated to be\begin{equation} y = (6.45 \pm 0.24) \times 10^{-3} , .\end{equation}This thesis also presents the work done for the EPFL fibre mat production as part of the LHCb Scintillating Fibre (SciFi) Tracker upgrade.

EPFL2022

Observation of CP violation in two-body B-(s)(0)-meson decays to charged pions and kaons

Jian Wang, Olivier Schneider, Yiming Li, Yi Zhang, Aurelio Bay, Guido Haefeli, Christoph Frei, Frédéric Blanc, Tatsuya Nakada, Michel De Cian, Luca Pescatore, François Fleuret, Elena Graverini, Chitsanu Khurewathanakul, Renato Quagliani, Maria Vieites Diaz, Federico Betti, Andrea Merli, Aravindhan Venkateswaran, Luis Miguel Garcia Martin, Vitalii Lisovskyi, Sebastian Schulte, Veronica Sølund Kirsebom, Mingkui Wang, Zhirui Xu, Lei Zhang, Jessica Prisciandaro, Mark Tobin, Minh Tâm Tran, Niko Neufeld, Matthew Needham, Marc-Olivier Bettler, Greig Alan Cowan, Maurizio Martinelli, Vladislav Balagura, Donal Patrick Hill, Liang Sun, Pietro Marino, Mirco Dorigo, Xiaoxue Han, Liupan An, Federico Leo Redi, Plamen Hristov Hopchev, Thibaud Humair, Maxime Schubiger, Hang Yin, Guido Andreassi, Violaine Bellée, Olivier Göran Girard, Axel Kuonen, Preema Rennee Pais, Pavol Stefko, Tara Nanut, Maria Elena Stramaglia, Tommaso Colombo, Vladimir Macko, Guillaume Max Pietrzyk, Evgenii Shmanin, Dipanwita Dutta, Zheng Wang, Yi Wang, Hans Dijkstra, Gerhard Raven, Peter Clarke, Frédéric Teubert, Giovanni Carboni, Victor Coco, Adam Davis, Paolo Durante, Wenyu Zhang, Yu Zheng, Anton Petrov, Maxim Borisyak, Feng Jiang, Chen Chen, Zhipeng Tang

The time-dependent CP asymmetries of B-0 -> pi(+)pi(-) and B-s(0) -> K+K- decays are measured using a data sample of pp collisions corresponding to an integrated luminosity of 1.9 fb(-1), collected with the LHCb detector at a centre-of-mass energy of 13TeV. The results are C-pi pi = 0.311 +/- 0.045 +/- 0.015; S-pi pi = 0.706 +/- 0.042 +/- 0.013; C-KK = 0.164 +/- 0.034 +/- 0.014; S-KK = 0.123 +/- 0.034 +/- 0.015; A(KK)(Delta Gamma) = -0.83 +/- 0.05 +/- 0.09; where the first uncertainties are statistical and the second systematic. The same data sample is used to measure the time-integrated CP asymmetries of B-0 -> K + pi(-) and B-s(0) -> K-pi(+) decays and the results are AB(CP)(B0) = -0.0824 +/- 0.0033 +/- 0.0033; A(CP)(Bs0) = 0.236 +/- 0.013 +/- 0.011. All results are consistent with earlier measurements. A combination of LHCb measurements provides the first observation of time-dependent CP violation in B-s(0) decays.

SPRINGER2021

Precision measurement of neutral charm meson mixing parameters

Guillaume Max Pietrzyk

This thesis presents a measurement of the neutral charm meson mixing parameters

y_{C\!P}^{KK} - y_{C\!P}^{K\pi}

and

y_{C\!P}^{\pi\pi} - y_{C\!P}^{K\pi}

using

D^0 \rightarrow K^-K^+

D^0 \rightarrow \pi^-\pi^+

and

D^0 \rightarrow K^-\pi^+

decays. These parameters correspond to the departure from unity of the ratio of the effective decay widths of

D^0 \rightarrow K^-K^+

D^0 \rightarrow \pi^-\pi^+

decays over the effective decay width of

D^0 \rightarrow K^-\pi^+

decays. \The measurement is done with the dataset collected in the Run 2 (2015-2018) of the Large Hadron Collider (LHC) by the LHCb experiment at CERN at a centre-of-mass energy of

13 \tev

, and corresponding to an integrated luminosity of

6 \, \mathrm{fb}^{-1}

. The

D^0

mesons originate from

D^{\ast+}(2010) \rightarrow D^0 \pi^+

y_{C\!P} - y_{C\!P}^{K\pi}

. In addition, the results allow for an improvement of the precision on the mixing parameter

y

by a factor of two, where

y

is connected to the width difference between the neutral charm meson mass eigenstates. The new world average value of

y

EPFL2022