Observation of B $$^0$$ 0 $$\rightarrow $$ → $$\uppsi $$ ψ (2S)K $$^0_\mathrm {S}\uppi ^+\uppi ^-$$ S 0 π + π - and B $$^0_\mathrm {s}$$ s 0 $$\rightarrow $$ → $$\uppsi $$ ψ (2S)K $$^0_\mathrm {S}$$ S 0 decays

Abstract

Abstract Using a data sample of

$$\sqrt{s}=13\,\text {TeV}$$

s

= 13

TeV

proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of

$$103\text {~fb}^{-1}$$

103

fb

- 1

, the

$$\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0}$$

B s 0

→ ψ

( 2S )

K

S

0

and

$$\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^+\uppi ^-$$

B 0

→ ψ

( 2S )

K

S

0

π +

π -

decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to

$${\mathcal {B}}(\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0})/{\mathcal {B}}(\text {B}^{0}\rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0}) = (3.33 \pm 0.69 (\text {stat})\, \pm 0.11\,(\text {syst}) \pm 0.34\,(f_{\mathrm{s}}/f_{\mathrm{d}})) \times 10^{-2}$$

B

(

B s 0

→ ψ

( 2S )

K

S

0

)

/ B

(

B 0

→ ψ

( 2S )

K

S

0

)

=

( 3.33 ± 0.69

( stat )

± 0.11

( syst )

± 0.34

(

f s

/

f d

)

)

×

10

- 2

and

$${\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^{+} \uppi ^{-})/ {\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}^{0}_{\mathrm{S}}) = 0.480 \pm 0.013\,(\text {stat}) \pm 0.032\,(\text {syst})$$

B

(

B 0

→ ψ

( 2S )

K

S

0

π +

π -

)

/ B

(

B 0

→ ψ

( 2S )

K S 0

)

= 0.480 ± 0.013

( stat )

± 0.032

( syst )

, where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of

$$\hbox {B}^{0}_{\mathrm{s}}$$

B s 0

and

$$\hbox {B}^{0}$$

B 0

mesons,

$$f_{\mathrm{s}}/f_{\mathrm{d}}$$

f s

/

f d

.