Measurement of the CKM angle $\gamma$ using the $B^{\pm}\rightarrow D^*h^{\pm}$ channels

Information

LHCb-PAPER-2023-012
CERN-EP-2023-170
arXiv:2310.04277 [PDF]

(Submitted on 06 Oct 2023)
JHEP 12 (2023) 013
Inspire 2709142

Tools

Abstract

A measurement of the $CP$-violating observables from $B^{\pm}\rightarrow D^* K^{\pm}$ and $B^{\pm}\rightarrow D^* \pi^{\pm}$ decays is presented, where $D^* (D) $ is an admixture of $D^{*0}$ and $\bar{D}^{*0}$ ($D^0$ and $\bar{D}^0$) states and is reconstructed through the decay chains $ D^* \rightarrow D\pi^0/\gamma$ and $D \to K_S^0 \pi^+\pi^-/K_S^0 K^+K^-$. The measurement is performed by analysing the signal yield variation across the $D$ decay phase space and is independent of any amplitude model. The data sample used was collected by the LHCb experiment in proton-proton collisions and corresponds to a total integrated luminosity of 9 fb$^{-1}$ at centre-of-mass energies of 7, 8 and 13 TeV. The CKM angle $\gamma$ is determined to be $(69^{+13}_{-14})^{\circ}$ using the measured $CP$-violating observables. The hadronic parameters $r^{D^* K^{\pm}}_B, r^{D^* \pi^{\pm}}_B, \delta^{D^* K^{\pm}}_B, \delta^{D^* \pi^{\pm}}_B$, which are the ratios and strong phase differences between favoured and suppressed $B^{\pm}$ decays, are also reported.

Figures and captions

(left) "Optimal" binning scheme \cite{Ablikim:2020lpk} used for $D\rightarrow K ^0_{\mathrm{S}} \pi^+\pi^-$ decays. (right) "2-bins" binning scheme \cite{Ablikim:2020cfp} used for $D\rightarrow K ^0_{\mathrm{S}} K^+K^-$ decays. They are the same as those in a previous model-independent measurement \cite{LHCb-PAPER-2020-019}.	binnin[..].pdf [145 KiB] HiDef png [315 KiB] Thumbnail [321 KiB] *.C file
	binnin[..].pdf [141 KiB] HiDef png [234 KiB] Thumbnail [235 KiB] *.C file
Projections of (left) $m( D h ^\pm )$ invariant-mass distribution and (right) $m( D \pi ^0 )$ invariant-mass distribution for the $ B ^\pm \rightarrow D ^* K ^\pm $ channels, reconstructed with the $ D ^* \rightarrow D \pi ^0 $, (a) $ D \rightarrow K ^0_{\mathrm{S}} K ^+ K ^- $ and (b) $ D \rightarrow K ^0_{\mathrm{S}} \pi^+\pi^-$ modes. The signal and in-reco $ D ^* $ contributions are shown as solid colours.	legend[..].pdf [221 KiB] HiDef png [495 KiB] Thumbnail [607 KiB] *.C file
	massfi[..].pdf [279 KiB] HiDef png [235 KiB] Thumbnail [147 KiB] *.C file
	legend[..].pdf [221 KiB] HiDef png [495 KiB] Thumbnail [607 KiB] *.C file
	massfi[..].pdf [285 KiB] HiDef png [277 KiB] Thumbnail [160 KiB] *.C file
Projections of (left) $m( D h ^\pm )$ invariant-mass distribution and (right) $m( D \pi ^0 )$ invariant-mass distribution for the $ B ^\pm \rightarrow D ^* \pi ^\pm $ channels, reconstructed with the $ D ^* \rightarrow D \pi ^0 $, (a) $ D \rightarrow K ^0_{\mathrm{S}} K ^+ K ^- $ and (b) $ D \rightarrow K ^0_{\mathrm{S}} \pi^+\pi^-$ modes. The signal and in-reco $ D ^* $ contributions are shown as solid colours.	legend[..].pdf [163 KiB] HiDef png [367 KiB] Thumbnail [475 KiB] *.C file
	massfi[..].pdf [261 KiB] HiDef png [209 KiB] Thumbnail [135 KiB] *.C file
	legend[..].pdf [163 KiB] HiDef png [367 KiB] Thumbnail [475 KiB] *.C file
	massfi[..].pdf [264 KiB] HiDef png [203 KiB] Thumbnail [127 KiB] *.C file
Projections of (left) $m( D h ^\pm )$ invariant-mass distribution and (right) $m( D \gamma)$ invariant-mass distribution for the $ B ^\pm \rightarrow D ^* K ^\pm $ channels, reconstructed with the $ D ^* \rightarrow D \gamma$, (a) $ D \rightarrow K ^0_{\mathrm{S}} K ^+ K ^- $ and (b) $ D \rightarrow K ^0_{\mathrm{S}} \pi^+\pi^-$ modes. The signal, in-reco $ D ^* $ and part-reco $ D ^*$ contributions are shown as solid colours.	legend[..].pdf [223 KiB] HiDef png [577 KiB] Thumbnail [712 KiB] *.C file
	massfi[..].pdf [295 KiB] HiDef png [474 KiB] Thumbnail [242 KiB] *.C file
	legend[..].pdf [223 KiB] HiDef png [577 KiB] Thumbnail [712 KiB] *.C file
	massfi[..].pdf [302 KiB] HiDef png [496 KiB] Thumbnail [260 KiB] *.C file
Projections of (left) $m( D h ^\pm )$ invariant-mass distribution and (right) $m( D \gamma)$ invariant-mass distribution for the $ B ^\pm \rightarrow D ^* \pi ^\pm $ channels, reconstructed with the $ D ^* \rightarrow D \gamma$, (a) $ D \rightarrow K ^0_{\mathrm{S}} K ^+ K ^- $ and (b) $ D \rightarrow K ^0_{\mathrm{S}} \pi^+\pi^-$ modes. The signal, in-reco $ D ^* $ and part-reco $ D ^*$ contributions are shown as solid colours.	legend[..].pdf [163 KiB] HiDef png [425 KiB] Thumbnail [537 KiB] *.C file
	massfi[..].pdf [267 KiB] HiDef png [361 KiB] Thumbnail [195 KiB] *.C file
	legend[..].pdf [163 KiB] HiDef png [425 KiB] Thumbnail [537 KiB] *.C file
	massfi[..].pdf [269 KiB] HiDef png [373 KiB] Thumbnail [199 KiB] *.C file
Expected asymmetry in each bin for (left) $B^{\pm} \rightarrow D^K^{\pm}$ and (right) $B^{\pm} \rightarrow D^ \pi^{\pm}$, calculated from the $ C P$ -violating observables measured in the default fit, are shown with the solid lines and obtained in fits with independent bin yields freely varied are shown with the error bars (data points). The vertical dashed lines separate the $ D \rightarrow K ^0_{\mathrm{S}} \pi^{+} \pi^{-}$ and $ D \rightarrow K ^0_{\mathrm{S}} K^{+} K^-$ bins on the horizontal axes.	newhis[..].pdf [261 KiB] HiDef png [211 KiB] Thumbnail [211 KiB] *.C file
	newhis[..].pdf [261 KiB] HiDef png [216 KiB] Thumbnail [213 KiB] *.C file
Confidence level at 68.2% and 95.5% probability for (left, green) $x^{ D ^* K}_{+},y^{ D ^* K}_{+}$, (left, violet) $x^{ D ^* K}_{-},y^{ D ^* K}_{-}$ and (right, green) $x^{ D ^* \pi}_{\xi},y^{ D ^* \pi}_{\xi}$ are measured in $B^{\pm}\rightarrow D ^* h^{\pm}$ decays from a profile likelihood scan.	xyfinalres.pdf [320 KiB] HiDef png [391 KiB] Thumbnail [342 KiB] *.C file
	xyxifinal.pdf [257 KiB] HiDef png [263 KiB] Thumbnail [281 KiB] *.C file
Confidence limits for the CKM angle $\gamma$, as determined from {\tt GammaCombo} \cite{GammaCombo, LHCb-PAPER-2021-033}.	cartes[..].pdf [14 KiB] HiDef png [165 KiB] Thumbnail [133 KiB] *.C file
Confidence level regions for the combination of physical parameters ($ \gamma , \delta_B^{ D ^* K}, r_B^{ D ^* K}, \delta_B^{ D ^* \pi}, r_B^{ D ^* \pi}$) of interest. The 68% (hashed blue area) and 95% (light blue area) are determined from {\tt GammaCombo} \cite{GammaCombo, LHCb-PAPER-2021-033}.	cartes[..].pdf [14 KiB] HiDef png [240 KiB] Thumbnail [145 KiB] *.C file
	cartes[..].pdf [14 KiB] HiDef png [342 KiB] Thumbnail [216 KiB] *.C file
	cartes[..].pdf [14 KiB] HiDef png [282 KiB] Thumbnail [172 KiB] *.C file
	cartes[..].pdf [15 KiB] HiDef png [516 KiB] Thumbnail [337 KiB] *.C file
Animated gif made out of all figures.	PAPER-2023-012.gif Thumbnail

Tables and captions

Yields of fully reconstructed $ D ^*$ contributions obtained from datasets with $ D \rightarrow K ^0_{\mathrm{S}} \pi^+\pi^-$ decays.	Table_1.pdf [60 KiB] HiDef png [130 KiB] Thumbnail [61 KiB] tex code
Yields of fully reconstructed $ D ^*$ contributions obtained from the datasets with $ D \rightarrow K ^0_{\mathrm{S}} K^+K^-$ decays.	Table_2.pdf [60 KiB] HiDef png [118 KiB] Thumbnail [57 KiB] tex code
Summary of uncertainties on the measurement of $x^{ D ^* K}_{\pm},y^{ D ^* K}_{\pm},x^{ D ^* \pi}_{\xi}$ and $y^{ D ^* \pi}_{\xi}$. All numbers have been scaled up by a factor of 100.	Table_3.pdf [84 KiB] HiDef png [102 KiB] Thumbnail [42 KiB] tex code
Statistical correlation matrix for $ C P$ -violating observables.	Table_4.pdf [72 KiB] HiDef png [51 KiB] Thumbnail [24 KiB] tex code
Systematic correlation matrix for considered LHCb related effects.	Table_5.pdf [71 KiB] HiDef png [46 KiB] Thumbnail [22 KiB] tex code
Systematic correlation matrix for the strong phase inputs.	Table_6.pdf [70 KiB] HiDef png [48 KiB] Thumbnail [24 KiB] tex code
Yields of incorrectly reconstructed and partially reconstructed $ D ^*$ contributions from datasets with $D\rightarrow K ^0_{\mathrm{S}} \pi^+\pi^-$ decays.	Table_7.pdf [76 KiB] HiDef png [283 KiB] Thumbnail [139 KiB] tex code
Yields of incorrectly reconstructed and partially reconstructed $ D ^*$ contributions from the datasets with $ D \rightarrow K_S^0K^+K^-$ decays.	Table_8.pdf [76 KiB] HiDef png [284 KiB] Thumbnail [140 KiB] tex code