TY - JOUR
T1 - Observation of π· βΒ―πΎ1β‘(1270)β’π+β’ππ and test of lepton flavor universality with π· βΒ―πΎ1β‘(1270)β’β+β’πβ
AU - BESIII Collaboration
AU - Ablikim, M.
AU - Achasov, M.N.
AU - Adlarson, P.
AU - Afedulidis, O.
AU - Ai, X.C.
AU - Aliberti, R.
AU - Amoroso, A.
AU - Kalantar-Nayestanaki, Nasser
AU - Kavatsyuk, Myroslav
AU - Messchendorp, Johan
PY - 2025/4/1
Y1 - 2025/4/1
N2 - By analyzing 7.93ββfbβ1 of π+β’πβ collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we report the observation of the semimuonic decays of π·+ βΒ―πΎ1β’(1270)0β’π+β’ππ and π·0 βπΎ1β’(1270)ββ’π+β’ππ with statistical significances of 12.5β’π and 6.0β’π, respectively. Their decay branching fractions are determined to be β¬β‘[π·+ βΒ―πΎ1β’(1270)0β’π+β’ππ] =(2.36 Β±0.2β’0+0.18β0.27 Β±0.48) Γ10β3 and β¬β‘[π·0 βπΎ1β’(1270)ββ’π+β’ππ] =(0.78 Β±0.1β’1+0.05β0.09 Β±0.15) Γ10β3, where the first and second uncertainties are statistical and systematic, respectively, and the third originates from the input branching fraction of Β―πΎ1β’(1270)0 βπΎββ’π+β’π0 or πΎ1β’(1270)β βπΎββ’π+β’πβ. Combining our branching fractions with the previous measurements of β¬β‘[π·+ βΒ―πΎ1β’(1270)0β’π+β’ππ] and β¬β‘[π·0 βπΎ1β’(1270)ββ’π+β’ππ], we determine the branching fraction ratios to be β¬β‘[π·+βΒ―πΎ1β’(1270)0β’π+β’ππ]/β¬β‘[π·+βΒ―πΎ1β’(1270)0β’π+β’ππ]=1.03Β±0.14+0.11β0.15 and β¬β‘[π·0βπΎ1β’(1270)ββ’π+β’ππ]/β¬β‘[π·0βπΎ1β’(1270)ββ’π+β’ππ]=0.74Β±0.13+0.08β0.13. Using the branching fractions measured in this work and the world-average lifetimes of the π·+ and π·0 mesons, we determine the semimuonic partial decay width ratio to be Ξβ‘[π·+βΒ―πΎ1β’(1270)0β’π+β’ππ]/Ξβ‘[π·0βπΎ1β’(1270)ββ’π+β’ππ]=1.22Β±0.10+0.06β0.09, which is consistent with unity as predicted by isospin conservation.
AB - By analyzing 7.93ββfbβ1 of π+β’πβ collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we report the observation of the semimuonic decays of π·+ βΒ―πΎ1β’(1270)0β’π+β’ππ and π·0 βπΎ1β’(1270)ββ’π+β’ππ with statistical significances of 12.5β’π and 6.0β’π, respectively. Their decay branching fractions are determined to be β¬β‘[π·+ βΒ―πΎ1β’(1270)0β’π+β’ππ] =(2.36 Β±0.2β’0+0.18β0.27 Β±0.48) Γ10β3 and β¬β‘[π·0 βπΎ1β’(1270)ββ’π+β’ππ] =(0.78 Β±0.1β’1+0.05β0.09 Β±0.15) Γ10β3, where the first and second uncertainties are statistical and systematic, respectively, and the third originates from the input branching fraction of Β―πΎ1β’(1270)0 βπΎββ’π+β’π0 or πΎ1β’(1270)β βπΎββ’π+β’πβ. Combining our branching fractions with the previous measurements of β¬β‘[π·+ βΒ―πΎ1β’(1270)0β’π+β’ππ] and β¬β‘[π·0 βπΎ1β’(1270)ββ’π+β’ππ], we determine the branching fraction ratios to be β¬β‘[π·+βΒ―πΎ1β’(1270)0β’π+β’ππ]/β¬β‘[π·+βΒ―πΎ1β’(1270)0β’π+β’ππ]=1.03Β±0.14+0.11β0.15 and β¬β‘[π·0βπΎ1β’(1270)ββ’π+β’ππ]/β¬β‘[π·0βπΎ1β’(1270)ββ’π+β’ππ]=0.74Β±0.13+0.08β0.13. Using the branching fractions measured in this work and the world-average lifetimes of the π·+ and π·0 mesons, we determine the semimuonic partial decay width ratio to be Ξβ‘[π·+βΒ―πΎ1β’(1270)0β’π+β’ππ]/Ξβ‘[π·0βπΎ1β’(1270)ββ’π+β’ππ]=1.22Β±0.10+0.06β0.09, which is consistent with unity as predicted by isospin conservation.
U2 - 10.1103/PhysRevD.111.L071101
DO - 10.1103/PhysRevD.111.L071101
M3 - Letter (Research letter)
SN - 1550-7998
VL - 111
JO - Physical Review D
JF - Physical Review D
IS - 7
M1 - L071101
ER -