CMS-PAS-BPH-15-009

CMS-PAS-BPH-15-009
Angular analysis of the decay ${\mathrm B^{+} \to \mathrm K^{*+} \mu^{+} \mu^{-}}$ in proton-proton collisions at $\sqrt{s}=$ 8 TeV
CMS Collaboration
July 2020

Abstract: Angular distributions of the decay ${\mathrm B^{+} \to \mathrm K^{+} \mu^{+} \mu^{-}}$ are studied using events collected with the CMS detector from $\sqrt{s}=$ 8 TeV proton-proton collisions, corresponding to an integrated luminosity of 20.0 fb $^{-1}$ . The forward-backward asymmetry of the muons and the longitudinal polarization of the $\mathrm K^{+}$ meson are determined for an integrated sample and as a function of the dimuon invariant mass squared. These are the first results from this exclusive decay mode and are in agreement with standard model predictions.
Links: CDS record (PDF) ; CADI line (restricted) ; These preliminary results are superseded in this paper, JHEP 04 (2021) 124. The superseded preliminary plots can be found here.

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: The signal efficiency as a function $\cos\theta _{\mathrm{K}}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 1-a: The signal efficiency as a function $\cos\theta _{\mathrm{K}}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 1-b: The signal efficiency as a function $\cos\theta _{\mathrm{K}}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 1-c: The signal efficiency as a function $\cos\theta _{\mathrm{K}}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 1-d: The signal efficiency as a function $\cos\theta _{\mathrm{K}}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 2: The signal efficiency as a function $\cos\theta _{\ell}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 2-a: The signal efficiency as a function $\cos\theta _{\ell}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 2-b: The signal efficiency as a function $\cos\theta _{\ell}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 2-c: The signal efficiency as a function $\cos\theta _{\ell}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 2-d: The signal efficiency as a function $\cos\theta _{\ell}$ for different ${q^2}$ ranges. The vertical bars indicate the statistical uncertainty. The curves show the fitted result, as described in the text.
png pdf	Figure 3: The fitted $\mathrm{B^{+}}$ invariant mass, $\mathrm {m}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 3-a: The fitted $\mathrm{B^{+}}$ invariant mass, $\mathrm {m}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 3-b: The fitted $\mathrm{B^{+}}$ invariant mass, $\mathrm {m}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 3-c: The fitted $\mathrm{B^{+}}$ invariant mass, $\mathrm {m}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 3-d: The fitted $\mathrm{B^{+}}$ invariant mass, $\mathrm {m}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 4: The fitted angular variable $\cos\theta _{\mathrm{K}}$ , for each ${q^2}$ range from the three dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 4-a: The fitted angular variable $\cos\theta _{\mathrm{K}}$ , for each ${q^2}$ range from the three dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 4-b: The fitted angular variable $\cos\theta _{\mathrm{K}}$ , for each ${q^2}$ range from the three dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 4-c: The fitted angular variable $\cos\theta _{\mathrm{K}}$ , for each ${q^2}$ range from the three dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 4-d: The fitted angular variable $\cos\theta _{\mathrm{K}}$ , for each ${q^2}$ range from the three dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars represent the statistical uncertainty.
png pdf	Figure 5: The fitted angular variable $\cos\theta _{\ell}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars on the points represent the statistical uncertainty.
png pdf	Figure 5-a: The fitted angular variable $\cos\theta _{\ell}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars on the points represent the statistical uncertainty.
png pdf	Figure 5-b: The fitted angular variable $\cos\theta _{\ell}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars on the points represent the statistical uncertainty.
png pdf	Figure 5-c: The fitted angular variable $\cos\theta _{\ell}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars on the points represent the statistical uncertainty.
png pdf	Figure 5-d: The fitted angular variable $\cos\theta _{\ell}$ , for each ${q^2}$ range from the three-dimensional fit to the data. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively. The vertical bars on the points represent the statistical uncertainty.
png pdf	Figure 6: The angular variable $\cos\theta _{\mathrm{K}}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 6-a: The angular variable $\cos\theta _{\mathrm{K}}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 6-b: The angular variable $\cos\theta _{\mathrm{K}}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 6-c: The angular variable $\cos\theta _{\mathrm{K}}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 6-d: The angular variable $\cos\theta _{\mathrm{K}}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 7: The angular variable $\cos\theta _{\ell}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 7-a: The angular variable $\cos\theta _{\ell}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 7-b: The angular variable $\cos\theta _{\ell}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 7-c: The angular variable $\cos\theta _{\ell}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 7-d: The angular variable $\cos\theta _{\ell}$ for the events in the signal region 5.18 $< m <$ 5.38 GeV, overlayed with the corresponding signal, background and total pdfs obtained from the final fit, for each ${q^2}$ range. The filled area, dashed lines, and solid lines represent the signal, background, and total contributions, respectively.
png pdf	Figure 8: The measured values of ${A_\mathrm {FB}}$ and ${F_\mathrm {L}}$ versus ${q^2}$ for ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{+}} \mu^{+} \mu^{-}}$ decays. The statistical (total) uncertainty is shown by inner (outer) vertical bars. The vertical shaded regions correspond to the ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{+}} {\mathrm{J}/\psi} (\mu^{+} \mu^{-})}$ and ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{*+}} \psi(\text{2S})(\mu^{+} \mu^{-})}$ dominated regions. The blue band shows the SM predictions for the corresponding ${q^2}$ range.
png pdf	Figure 8-a: The measured values of ${A_\mathrm {FB}}$ and ${F_\mathrm {L}}$ versus ${q^2}$ for ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{+}} \mu^{+} \mu^{-}}$ decays. The statistical (total) uncertainty is shown by inner (outer) vertical bars. The vertical shaded regions correspond to the ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{+}} {\mathrm{J}/\psi} (\mu^{+} \mu^{-})}$ and ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{*+}} \psi(\text{2S})(\mu^{+} \mu^{-})}$ dominated regions. The blue band shows the SM predictions for the corresponding ${q^2}$ range.
png pdf	Figure 8-b: The measured values of ${A_\mathrm {FB}}$ and ${F_\mathrm {L}}$ versus ${q^2}$ for ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{+}} \mu^{+} \mu^{-}}$ decays. The statistical (total) uncertainty is shown by inner (outer) vertical bars. The vertical shaded regions correspond to the ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{+}} {\mathrm{J}/\psi} (\mu^{+} \mu^{-})}$ and ${\mathrm{B^{+}} \to {{\mathrm{K}} ^{*+}} \psi(\text{2S})(\mu^{+} \mu^{-})}$ dominated regions. The blue band shows the SM predictions for the corresponding ${q^2}$ range.

Tables
png pdf	Table 1: Sources of systematic uncertainties and the effect on ${A_\mathrm {FB}}$ and ${F_\mathrm {L}}$ . The values given are absolute and the ranges indicate the variation over the four ${q^2}$ bins.
png pdf	Table 2: The signal yield with statistical uncertainty and the fitted ${A_\mathrm {FB}}$ and ${F_\mathrm {L}}$ values with statistical and systematic uncertainties, for each ${q^2}$ range.

Summary

The first angular analysis of the decay

${\mathrm{B^{+}}\to {\mathrm K^{*+}} \mu^{+} \mu^{-}}$ has been performed using a sample of proton-proton collisions at a center-of-mass energy of 8 TeV. The data were collected with the CMS detector in 2012 and correspond to an integrated luminosity of 20.0 fb

$^{-1}$ . For each bin of dimuon invariant mass squared (

${q^2}$ ), a three-dimensional unbinned maximum-likelihood fit was performed to the distributions of the

${\mathrm K^{*+}} \mu^{+}\mu^{-}$ invariant mass and two decay angles. The forward-backward asymmetry,

${A_\mathrm{FB}}$ , of the muon system and the longitudinal polarization of

${\mathrm K^{*+}} , {F_\mathrm{L}}$ , are extracted from the fit and compared with predictions from a standard model prediction. The results are consistent with standard model expectations.

References
1	C. Bobeth, G. Hiller, and D. van Dyk	The benefits of $\overline{B} \to \overline{K}^* \ell^+ \ell^-$ decays at low recoil	JHEP 07 (2010) 098	1006.5013
2	C. Bobeth, G. Hiller, D. van Dyk, and C. Wacker	The decay $\overline{B} \to \overline{K} \ell^+ \ell^-$ at low hadronic recoil and model-independent $\delta b =$ 1 constraints	JHEP 01 (2012) 107	1111.2558
3	C. Bobeth, G. Hiller, and D. van Dyk	General analysis of $\overline{B} \to \overline{K}{}^{(*)} \ell^+ \ell^-$ decays at low recoil	PRD 87 (2012) 034016	1212.2321
4	A. Ali, G. Kramer, and G. Zhu	$B\to K^*\ell^+\ell^-$ decay in soft-collinear effective theory	EPJC 47 (2006) 625	hep-ph/0601034
5	W. Altmannshofer et al.	Symmetries and asymmetries of $B \to K^{*} \mu^{+} \mu^{-}$ decays in the Standard Model and beyond	JHEP 01 (2009) 019	0811.1214
6	W. Altmannshofer, P. Paradisi, and D. M. Straub	Model-independent constraints on new physics in $b \to s$ transitions	JHEP 04 (2012) 008	1111.1257
7	S. Jager and J. Martin Camalich	On $B \to V \ell \ell$ at small dilepton invariant mass, power corrections, and new physics	JHEP 05 (2013) 043	1212.2263
8	S. Descotes-Genon, T. Hurth, J. Matias, and J. Virto	Optimizing the basis of $B \to {K}^{*}\ell^+ \ell^-$ observables in the full kinematic range	JHEP 05 (2013) 137	1303.5794
9	S. Descotes-Genon, L. Hofer, J. Matias, and J. Virto	On the impact of power corrections in the prediction of $B \to K^*\mu^+\mu^-$ observables	JHEP 12 (2014) 125	1407.8526
10	M. Algueró et al.	Are we overlooking lepton flavour universal new physics in $b\to s\ell\ell$ ?	PRD 99 (2019) 075017	1809.08447
11	M. Algueró et al.	Emerging patterns of New Physics with and without Lepton Flavour Universal contributions	EPJC 79 (2019) 714	1903.09578
12	CMS Collaboration	CMS luminosity based on pixel cluster counting - summer 2013 update	CMS-PAS-LUM-13-001	CMS-PAS-LUM-13-001
13	CDF Collaboration	Measurements of the angular distributions in the decays $B \to K^{(*)} \mu^+ \mu^-$ at CDF	PRL 108 (2012) 081807	1108.0695
14	LHCb Collaboration	Differential branching fraction and angular analysis of the decay $B^{0} \to K^{*0} \mu^{+}\mu^{-}$	JHEP 08 (2013) 131	1304.6325
15	CMS Collaboration	Angular analysis and branching fraction measurement of the decay $B^0 \to K^{*0} \mu^+\mu^-$	PLB 727 (2013) 77	CMS-BPH-11-009 1308.3409
16	CMS Collaboration	Angular analysis of the decay $B^0 \to K^{*0} \mu^+ \mu^-$ from pp collisions at $\sqrt{s} =$ 8 TeV	PLB 753 (2016) 424	CMS-BPH-13-010 1507.08126
17	BaBar Collaboration	Angular distributions in the decay $B \to K^* \ell^+ \ell^-$	PRD 79 (2009) 031102	0804.4412
18	Belle Collaboration	Measurement of the differential branching fraction and forward-backward asymmetry for $B \to K^{(*)} \ell^+ \ell^-$	PRL 103 (2009) 171801	0904.0770
19	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
20	CMS Collaboration	The CMS trigger system	JINST 12 (2017) P01020	CMS-TRG-12-001 1609.02366
21	T. Sjostrand, S. Mrenna, and P. Skands	PYTHIA 6.4 physics and manual	JHEP 05 (2006) 026	hep-ph/0603175
22	D. J. Lange	The EvtGen particle decay simulation package	NIMA 462 (2001) 152
23	GEANT4 Collaboration	GEANT4---a simulation toolkit	NIMA 506 (2003) 250
24	D. Be\vcirevi\'c and A. Tayduganov	Impact of $B\to K^{0} \ell^+\ell^-$ on the New Physics search in $B\to K^ \ell^+\ell^-$ decay	NPB 868 (2013) 368	1207.4004
25	J. Matias	On the S-wave pollution of $B \to K^* \ell^+\ell^-$ observables	PRD 86 (2012) 094024	1209.1525
26	T. Blake, U. Egede, and A. Shires	The effect of $S$ -wave interference on the $B^0 \rightarrow K^{*0} \ell^+ \ell^-$ angular observables	JHEP 03 (2013) 027	1210.5279
27	G. J. Feldman and R. D. Cousins	Unified approach to the classical statistical analysis of small signals	PRD 57 (1998) 3873	physics/9711021