Semileptonic and leptonic charm decays at BESIII Yue Wang (on behalf - - PowerPoint PPT Presentation
Semileptonic and leptonic charm decays at BESIII Yue Wang (on behalf of the BESIII collaboration) University of Science and Technology of China HADRON 2019, Guilin, China, August 16-21, 2019 BESIII Semileptonic and leptonic charm decays at
Yue Wang (on behalf of the BESIII collaboration) University of Science and Technology of China HADRON 2019, Guilin, China, August 16-21, 2019
BESIII Semileptonic and leptonic charm decays at BESIII 1 / 26
D c ¯ q W + ℓ+ νℓ Vcq fD D c ¯ q q′ ¯ q W + ℓ+ νℓ Vcq′ F V (A)
M ∝ |Vcs(d)|HµLµ test the unitarity of quark mixing matrix and search for new physics. test the theoretical calculation on decay constants and form factors, especially LQCD. test the lepton flavor universality. help to understand the internal structure of light scalar mesons. measure the semileptonic Λ+
c decays. BESIII Semileptonic and leptonic charm decays at BESIII 2 / 26
(@3.773 GeV) and D+
s (@4.18 and 4.01 GeV) data set at BESIII
Pair production at threshold, high efficiency and very low background.
MARKIII BESII CLEOc BESIII
Luminosity pb 1000 2000 3000
D D
*- s
D
+ s
D
D
+ s
D
e+ e− D ¯ D X hadrons ℓ+ νℓ X
Bsig = N i
DT
N i
STǫi DT/ǫi ST
ǫi
ST/DT: The efficiency of ST/DT
Bi
ST/DT: The BF of ST/DT
The number of signal events is determined by examining the kinematic variables of the missing neutrino Umiss = Emiss − | p|miss M 2
miss = E2 miss − |
p|2
miss BESIII Semileptonic and leptonic charm decays at BESIII 3 / 26
BESIII Semileptonic and leptonic charm decays at BESIII 4 / 26
s leptonic decays
Γ(D+
s → ℓ+νℓ) = G2
F
8π |Vcs|2f2 D+
s m2
ℓmD+
s (1 −
m2
ℓ
m2
D+ s
)2
)
2
)
2
Events / ( 0.0175 (GeV/c 2 4 6 8 10 12 14 16 18 20 22 24 )
2
)
2
Events / ( 0.0175 (GeV/c 2 4 6 8 10 12 14 16 18 20 22 24 (a) )
2
)
2
((GeV/c
2
MM
0.05 0.1 0.15 0.2 2 4 6 8 10 )
2
)
2
((GeV/c
2
MM
0.05 0.1 0.15 0.2 2 4 6 8 10 (b)
PRD94(2016)072004 BESIII@4.009
ST D signal region
µ+νµ τ +ντ
ST D sideband region
0.1 0.2 100 200 300
data ) π ( γ but wrong
µ
ν
+
µ →
+ s
and D
BKGI: real ST D
µ
ν
+
µ →
+ s
BKGII: wrong ST D
)
4
/c
2
(GeV
2 miss
M
2
Events / 16 MeV/c
PRL122(2019)071802 BESIII@4.178 1135.0 ± 33.1 B(D+
s → µ+νµ) = (5.49 ± 0.16 ± 0.15) × 10−3
fD+
s |Vcs| = 246.2 ± 3.6 ± 3.5 MeV
RD+
s = Γ(D+ s →τ+ντ )
Γ(D+
s →µ+νµ) = 9.98 ± 0.52
SM prediction 9.74 ± 0.01.
BESIII Semileptonic and leptonic charm decays at BESIII 5 / 26
s
Inputs: PDG2018 from CKM unitarity: |Vcs| = 0.97359+0.00010
−0.00011
LQCD average: fLQCD
D+
s
= 249.7 ± 0.4 MeV fD→K
+
(0)LQCD = 0.760 ± 0.011
[MeV]
s +
D
f 200 220 240 260
) ν µ CLEO-c ( ) ν µ BaBar ( ) ν µ Belle ( ) ν µ BESIII(a) ( ) ν µ BESIII(b) ( ) ν
ρ ,e, π
τ CLEO-c ( ) ν
µ e,
τ BaBar ( ) ν
µ ,e, π
τ Belle ( ) ν
π
τ BESIII(a) ( ) ν
π
τ BESIII(a) ( Average Average (theory) FMILC (2+1+1) ETM (2+1+1) RBCUKQCD (2+1) QCD (2+1) χ HPQCD (2+1)
|
cs
|V 0.8 0.9 1 1.1
ν e
S
K →
+
D BESIII ν 'e η →
s
D BESIII ν e η →
s
D BESIII ν µ K → D BESIII ν l →
s
D ν l K → D Average ν l K → +D ν l →
s
D s c → W Indirect 0.13 ±
+0.32
0.94
+0.000074
0.973394
❥ ❣
BESIII Semileptonic and leptonic charm decays at BESIII 6 / 26
]
4
/c
2
[GeV
miss 2
M
0.2 0.4 0.6 Number of Events
10 1 10
2
10
3
10
Data
µν
+µ →
+D
+π
LK →
+D π
+π →
+D
τν
+τ →
+D Other D decays processes D non-D
]
4
/c
2
[GeV
miss 2
M
0.2 0.4 0.6 Number of Events
10 1 10
2
10
3
10
PRD89(2014)051104 D+ → µ+νµ 409 ± 21 B(D+ → µ+νµ) = (3.71 ± 0.19 ± 0.06) × 10−4 fD+|Vcd| = 45.75 ± 1.20 ± 0.39 MeV
❍ ❍ ❥
D+→µ+νµ
PP P q
D+→τ+ντ
❅ ❘
D+→π+KL
B(D+ → τ +ντ) = (1.20 ± 0.24stat) × 10−3 fD+|Vcd| = 50.4 ± 5.0stat MeV First evidence with 4σ statistical significance. RD+ = Γ(D+→τ+ντ )
Γ(D+→µ+νµ) = 3.21 ± 0.64
SM prediction 2.66 ± 0.01. Consistent
BESIII Semileptonic and leptonic charm decays at BESIII 7 / 26
Inputs: PDG2018 from CKM unitarity: |Vcd| = 0.22438 ± 0.00044 LQCD average: fLQCD
D+
= 212.3 ± 0.6 MeV fD→π
+
(0)LQCD = 0.634 ± 0.015
[MeV]
+
D
f 190 200 210 220
) ν µ CLEO-c ( ) ν µ BESIII ( ) ν τ BESIII ( preliminary ) ν µ Average ( Average (theory) FMILC (2+1+1) ETM (2+1+1) RBCUKQCD (2+1) HPQCD (2+1)
|
cd
|V 0.2 0.22 0.24
ν e π →
+
D BESIII ν µ → D ν l π → D Average ν )l π ( → D N ν Indirect
✚✙ ✛✘ ✖✕ ✗✔
BESIII Semileptonic and leptonic charm decays at BESIII 8 / 26
<P(p2)|V µ|D(p1)>=f+(q2)[P µ−
M2 1 −M2 2 q2
qµ]+f0(q2)
M2 1 −M2 2 q2
qµ qµLµ→0 when
mℓ → 0
Single pole model: f+(q2) =
f+(0) 1− q2 M2 pole
Modified pole mode: f+(q2) =
f+(0) (1− q2 M2 pole )(1−α q2 M2 pole )
z series(2 par): f+(t) =
1 P (t)Φ(t,t0) a0(t0) × (1 + r1(t0)[z(t, t0)])
z series(3 par): f+(t) =
1 P (t)Φ(t,t0) a0(t0) × (1 + r1(t0)[z(t, t0)] + r2(t0)[z(t, t0)]2)
2000 4000 2000 4000
(a)
2000 4000
0.1 0.2 100 200 300 400
0.1 0.2 100 200 300 400
(b)
0.1 0.2 100 200 300 400
(GeV)
miss
U Events / ( 2.5 MeV )
PRD92(2015)072012
D0→K−e+νe 70727.0±278.3 D0→π−e+νe 6297.1±86.8 )
4
/c
2
(GeV
2
q
0.5 1 1.5 2
)
4
c
GeV
(ns
2
/q Γ ∆
20 40 60 80 100
eν
+e
→ D data Single pole model Modified pole model z series (2 par.) z series (3 par.)
)
4
/c
2
(GeV
2
q
1 2 3
)
4
c
GeV
(ns
2
/q Γ ∆
2 4 6
eν
+e
→ D data Single pole model Modified pole model z series (2 par.) z series (3 par.)
D0→K−e+νe D0→π−e+νe
B(D0 → K−e+νe) (3.505 ± 0.014 ± 0.033)% fD→K
+
(0)|Vcs| 0.7172 ± 0.0025 ± 0.0035 B(D0 → π−e+νe) (0.295 ± 0.004 ± 0.003)% fD→π
+
(0)|Vcd| 0.1435 ± 0.0018 ± 0.0009
BESIII Semileptonic and leptonic charm decays at BESIII 9 / 26
(GeV)
miss
U
0.1 0.2
Events / ( 2.5 MeV ) (GeV)
miss
U
0.1 0.2
Events / ( 2.5 MeV )
5 10 15 20
2
10 ×
(a)
D+→ ¯ K0e+νe
PRD96(2017)012002 (GeV)
miss
U
0.2 0.4
Events / ( 5.0 MeV ) (GeV)
miss
U
0.2 0.4
Events / ( 5.0 MeV )
1 2 3
2
10 ×
(b)
D+→π0e+νe B(D+→ ¯ K0e+νe) (via K0 S) (8.60±0.06±0.15)% fD→K + (0)|Vcs| 0.7053±0.0040±0.0112 B(D+→π0e+νe) (0.363±0.008±0.005)% fD→π + (0)|Vcd| 0.1400±0.0026±0.0007
)
4
/c
2
(GeV
2
q
0.5 1 1.5 2
)
4
c
GeV
(ns
2
/dq Γ d
20 40 60 80 100
e
ν
+
e K →
+
D Data Single Pole Model Modified Pole Model ISGW2 Model z series (2 par.) z series (3 par.)
)
4
/c
2
(GeV
2
q
1 2 3
)
4
c
GeV
(ns
2
/dq Γ d
0.0 0.5 1.0 1.5 2.0 2.5
e
ν
+
e π →
+
D Data Single Pole Model Modified Pole Model ISGW2 Model z series (2 par.) z series (3 par.)
D+ → ¯ K0e+νe D+ → π0e+νe BESIII Semileptonic and leptonic charm decays at BESIII 10 / 26
PRL122(2019)011804
D0→K−π+π0
(GeV)
missU Events /(0.005 GeV) 1000 2000 3000 4000 1000 2000 3000 4000 (a)
0.0 0.1 0.2 0.3 100 200 300 400
0.0 0.1 0.2 0.3 100 200 300 400 (b)
¯ K0→π+π− ¯ K0→π0π0
EPJC76(2016)369
D+→ ¯ K0π+π0
❍ ❍ ❍ ❨
0.5 1 1.5 20 40 60 80
(a)
0.5 1 1.5 1 1.5
(b)
0.5 1 1.5 1 1.5
(c) )
4
/c
2
(GeV
2
q )
4
/c
2
(GeV
2
q )
4
/c
2
(GeV
2
q )
4
c
GeV
(ns
2
q ∆ / Γ ∆ )
2
(q
K +
f
/e µ
R
D0→K−µ+νµ
B(D0 → K−µ+νµ) (3.431 ± 0.019 ± 0.035)% fD→K
+
(0)|Vcs| 0.7133 ± 0.0038 ± 0.0030 B(D+ → ¯ K0µ+νµ) (8.72 ± 0.07 ± 0.18)%
Γ(D0→K−µ+νµ) Γ(D0→K−e+νe)
0.974 ± 0.014
Γ(D+→ ¯ K0µ+νµ) Γ(D+→ ¯ K0e+νe)
0.988 ± 0.033 Expected: 0.975 ± 0.001 Consistent
BESIII Semileptonic and leptonic charm decays at BESIII 11 / 26
)
4
/c
2
Events /(0.007 GeV )
4
/c
2
(GeV
2 miss
M )
4
/c
2
(GeV
2 miss
M
0.0 0.2 0.4 200 400 600 0.0 0.2 0.4 200 400 600
µ
ν
+
µ
→ D 0.0 0.2 0.4 0.0 0.2 0.4
µ
ν
+
µ π →
+
D
Data Signal BKGI BKGII BKGIII
PRL121(2018)171803
D0/+→π−/0π+ ¯ K0
❅ ❘
)
4
c
GeV
(ns
2
q ∆ / Γ ∆ 2 4
ν
+
l
→ D ν
+
l π →
+
D
)
4
/c
2
(GeV
2
q 1 2
LFU
R 0.5 1 1.5 )
4
/c
2
(GeV
2
q 1 2 3
(l=e)
2
q ∆ / Γ ∆ ) µ (l=
2
q ∆ / Γ ∆
LFU
R Data LQCD
B(D0 → π−µ+νµ) = (0.272 ± 0.008 ± 0.006)% B(D+ → π0µ+νµ) = (0.350 ± 0.011 ± 0.010)%
Γ(D0→π−µ+νµ) Γ(D0→π−e+νe) = 0.922 ± 0.037 Γ(D+→π0µ+νµ) Γ(D+→π0e+νe) = 0.964 ± 0.045
The LQCD calculations are taken from ETM’s results published in PRD96(2017)054514, with
Γ(D→πµ+νµ) Γ(D→πe+νe) = 0.985 ± 0.002
.
BESIII Semileptonic and leptonic charm decays at BESIII 12 / 26
+
+
Inputs: PDG2018 from CKM unitarity: |Vcs| = 0.97359+0.00010
−0.00011
|Vcd| = 0.22438 ± 0.00044
(0)
K → D +
f 0.65 0.7 0.75 0.8
ν e
ν e K CLEOc ν e
ν l K Belle ν e
ν e
L
BESIII K ν e
S
BESIII K ν µ
HFLAV HPQCD(2+1) ETM(2+1+1) FMILC(2+1+1) arXiv:1901.08989 Average
(0)
π → D +
f 0.55 0.6 0.65 0.7
ν e
BESII ν e π CLEOc ν e
BaBar ν l π Belle ν e
BESIII ν e π BESIII HFLAV HPQCD(2+1) ETM(2+1+1) FMILC(2+1+1) arXiv:1901.08989 Average
✒✑ ✓✏ ✒✑ ✓✏
BESIII Semileptonic and leptonic charm decays at BESIII 13 / 26
s → η(′)e+νe
0.2 0.4 200 400 600
e
ν
+
e
γ γ
η
0.2 0.4 50 100 150
e
ν
+
e
π π
η
0.2 0.4 20 40
e
ν
+
e
π
γ γη
’ η
0.2 0.4 50 100
e
ν
+
e
ρ γ
’ η )
4
c /
2
(GeV
2
MM )
4
c /
2
Events / (30 MeV
0.5 1 1.5 0.5 1 1.5 0.4 0.6 0.8 1
Simple pole Modified pole Series 2 Par.
e
ν
+
e
γ γ
η
e
ν
+
e
π π
η
0.2 0.4 0.6 0.8
0.4 0.6 0.8 1
e
ν
+
e
π
γ γη
’ η
e
ν
+
e
ρ γ
’ η LCSR calculation LCSR uncertainties
)
4
/c
2
(GeV
2
q )
2
(q
+
f PRL122(2019)121801 PRD88(2013)034023 B(D+
s → ηe+νe) = (2.323 ± 0.063 ± 0.063)%
fD+
s →η
+
(0)|Vcs| = 0.4455 ± 0.0053 ± 0.0044 B(D+
s → η′e+νe) = (0.824 ± 0.073 ± 0.027)%
fD+
s →η′
+
(0)|Vcs| = 0.477 ± 0.049 ± 0.011
(0)
η +
f
0.2 0.4 0.6 0.8
PRD 91 014503 PRD 91 014503 BES III PRL(122)121801 0.0045 ± 0.0054 ± 0.4576 LCSR PRD(88)034023 0.033 ± 0.432 LCSR JHEP(1511)138 0.030 ± 0.495 =470MeV
πLQCD M 0.011 ± 0.564 =370MeV
πLQCD M 0.013 ± 0.542 LCSR JPG(38)095001 0.15 ± 0.45 CCQM PRD(98)114031 0.12 ± 0.78 3PSR PLB(520)78 0.04 ± 0.50 CQM PRD(62)014006 0.78 CLFQM JPG(39)025005 0.76
(0)
’ η +
f
0.2 0.4 0.6 0.8
PRD 91 014503 PRD 91 014503 BESIII PRL(122)121801 0.011 ± 0.050 ± 0.490 LCSR PRD(88)034023 0.088 ± 0.520 LCSR JHEP(1511)138 0.047 ± 0.588 =470MeV
πLQCD M 0.018 ± 0.437 =370MeV
πLQCD M 0.025 ± 0.404 LCSR JPG(38)095001 0.18 ± 0.55 CQM PRD(62)014006 0.78 CCQM PRD(98)114031 0.11 ± 0.73
BESIII Semileptonic and leptonic charm decays at BESIII 14 / 26
(GeV)
miss
U Events/(0.02 GeV) (GeV)
miss
U Events/(0.02 GeV)
e
ν
+
e η γ γ → η 0.0-0.6 (a) 20 40 60
e
ν
+
e η π
+
π → η 0.0-0.6 (d) 10 20
e
ν
+
’e η
γ γ
η
+
π → ’ η
(g)
0.1
5 10 15 20
e
ν
+
e η γ γ → η 0.6-1.2 (b)
e
ν
+
e η π
+
π → η 0.6-1.2 (e)
e
ν
+
’e η ρ γ → ’ η
(h)
0.1
e
ν
+
e η γ γ → η >1.2 (c)
e
ν
+
e η π
+
π → η >1.2 (f)
e
ν
+
’e η
π 3
η
+
π → ’ η
(i)
0.1
PRD97(2018)092009
)
4
/c
2
(GeV
2
q )
(ns Γ ∆
0.5 1 1.5
0.2 0.4 0.6
Data Simple pole Modified pole Series expansion
B(D+ → ηe+νe) = (10.74 ± 0.81 ± 0.51) × 10−4 fD+→η
+
(0)|Vcd| = B(D+ → η′e+νe) = (1.91 ± 0.51 ± 0.13)−4 (7.86 ± 0.64 ± 0.21) × 10−2
(0)
η +
f
0.2 0.4 0.6 0.8
BES III PRD 97 092009 0.01 ± 0.03 ± 0.35 CLEO-c 84 PRD 032001 0.01 ± 0.03 ± 0.38 LCSR PRD 88 034023 0.051 ± 0.552 LCSR JHEP 1511 138 0.165 ± 0.429 CCQM PRD 98 114031 0.11 ± 0.67 CLFQM JPG 39 025005 0.71
Model independent determination of η − η′ mixing angle.
Γ(D+ s →η′e+νe)/Γ(D+ s →ηe+νe) Γ(D+→η′e+νe)/Γ(D+→ηe+νe)
≃cot4 ΦP
ΦP = (40.1 ± 2.1 ± 0.7)◦
(degree)
P
φ 28 30 32 34 36 38 40 42 44
BESIII
e
ν
+
e
(’)
η →
+ (s)
D KLOE γ
(’)
η → φ KLOE γ
(’)
η → φ LHCb
(’)
η ψ J/ →
(s)
B
(Gluon excluded) (Gluon excluded) (Gluon included)
CLEO
e
ν
+
e
(’)
η →
+ (s)
D
BESIII Semileptonic and leptonic charm decays at BESIII 15 / 26
< V (p2, ǫ2)|V µ − Aµ|D(p1) >= −(M1 + M2)ǫ∗µ
2 A1(q2) + ǫ∗
2q
M1+M2 P µA2(q2) +
2M2
ǫ∗
2q
q2 qµ[A3(q2) − A0(q2)] + 2iǫµνρσǫ∗νpρ
1pσ 2
M1+M2
V (q2) qµLµ → 0 when mℓ → 0 rV =
V (0) A1(0)
r2 = A2(0)
A1(0)
(GeV)
miss
U
0.1 0.2 Events/(0.01 GeV) 500 1000 (GeV)
miss
U
0.1 0.2 Events/(0.01 GeV) 500 1000 data fit bkg (a) )
2
(GeV/c
K
M 0.8 1 1.2 )
2
Events/(0.02 GeV/c
10 1 10
2
10
3
10 (b) )
4
/c
2
(GeV
2
q 0.2 0.4 0.6 0.8 1 )
4
/c
2
Events/(0.04 GeV 50 100 150 200 (c)
+e
θ cos
0.5 Events/0.1 100 200 (d)
K
θ cos
0.5 Events/0.1 100 200 300 (e) (radians) χ
2 ) π Events/(0.1 50 100 150 200 (f)
PRD99(2019)011103
D0 → ¯ K0π−e+νe
S(( ¯ K0π)S−wave) (7.90 ± 1.40 ± 0.91) × 10−4 P(K∗(892)−) (1.355 ± 0.031 ± 0.032)% rV 1.46 ± 0.07 ± 0.02 r2 0.67 ± 0.06 ± 0.01
BESIII Semileptonic and leptonic charm decays at BESIII 16 / 26
(GeV)
miss
U
0.1 0.2
Events/(5.0 MeV)
50 100 150
(a) D0→π−π0e+νe
PRL122(2019)062001
(GeV)
miss
U
0.1 0.2
Events/(5.0 MeV)
100 200 300
(b) D+→π−π+e+νe
Signal mode BF (×10−3)
D0→π−π0e+νe 1.445±0.058±0.039 D0→ρ−e+νe 1.445±0.048±0.039 D+→π−π+e+νe 2.449±0.074±0.073 D+→ρ0e+νe 1.860±0.070±0.061 D+→ωe+νe 2.05±0.66±0.30 D+→f0(500)e+νe f0(500)→π+π− 0.630±0.043±0.032 D+→f0(980)e+νe f0(980)→π+π− <0.028
rV = 1.695 ± 0.083 ± 0.051 r2 = 0.845 ± 0.056 ± 0.039 )
2
(GeV/c
π
m
0.5 1 )
2
Events/(0.017 GeV/c 50 100
(a)
D0→π−π0e+νe
)
4
/c
2
(GeV
2
q
0.5 1 1.5 )
4
/c
2
Events/(0.10 GeV 50 100 150
(b)
π
θ cos
0.5 1 Events/(0.25) 100 200 300
(c)
e
θ cos
0.5 1 Events/(0.25) 100 200 300
(d)
χ
2 Events/(0.79) 100 200
(e)
)
2
(GeV/c
+
π
m
0.5 1 )
2
Events/(0.017 GeV/c 50 100 150
(f)
D+→π−π+e+νe
)
4
/c
2
(GeV
2
q
0.5 1 1.5 )
4
/c
2
Events/(0.10 GeV 50 100 150 200
(g)
π
θ cos
0.5 1 Events/(0.25) 100 200 300 400
(h)
e
θ cos
0.5 1 Events/(0.25) 100 200 300 400
(i)
χ
2 Events/(0.79) 100 200 300 400
(j)
BESIII Semileptonic and leptonic charm decays at BESIII 17 / 26
s → K(∗)0e+νe
)
4
/c
2
(GeV
2
MM
0.1 0.2
4
/c
2
Events/0.010 GeV 10 20
e
ν
+
e K →
+ s
D
)
4
/c
2
(GeV
2
MM
0.1 0.2
4
/c
2
Events/0.010 GeV 10 20 30 40
e
ν
+
e
*0
K →
+ s
D
PRL122(2019)061801
B(D+
s →K0e+νe)=(3.25±0.38±0.16)×10−3
f
D+ s →K0 +
(0)|Vcd|=0.162±0.019±0.003 B(D+
s →K∗0e+νe)=(2.37±0.26±0.20)×10−3
rV =1.67±0.34±0.16 r2=0.77±0.28±0.07
)
4/c
2(GeV
2q 0.5 1 1.5 2 )
4c
GeV
(ns
2/dq Γ d 2 4 6 8
data simple pole modified pole z series (2 par.) (a)
)
4/c
2(GeV
2q 0.5 1 1.5 2 )
2(q
+f 1 1.5 2
data simple pole modified pole z series (2 par.) (b)
)
2(GeV/c
M 0.85 0.9 0.95
2Events/0.01 GeV/c 10 20 30
(c)
)
4/c
2(GeV
2q 0.5 1
4/c
2Events/0.12 GeV 10 20 30 40
(d)
eθ cos
0.5 1 Events/0.2 10 20 30 40
(e)
Kθ cos
0.5 1 Events/0.2 20 40
(f)
(radians) χ
2 π Events/0.2 10 20 30 40
(g)
f
D+
s →K0
+
(0)/f D+→π0
+
(0) = 1.16 ± 0.14 ± 0.02 r
D+
s →K∗0
V
/rD+→ρ0
V
= 1.13 ± 0.26 ± 0.11 r
D+
s →K∗0
2
/rD+→ρ0
2
= 0.93 ± 0.36 ± 0.10 Agrees with U-spin (d ↔ s) symmetry.
BESIII Semileptonic and leptonic charm decays at BESIII 18 / 26
)
2
Event/(0.05GeV/c Events/(0.04GeV) 10
(a)
20 (b) 20
(c)
10
(d)
)
2
(GeV/c
π η
M
0.8 1 1.2
U(GeV)
0.1 0.2
PRL121(2018)081802
D0→a0(980)−e+νe D+→a0(980)0e+νe
A model-independent way to study the nature of light scalar mesons proposed by PRD82(2016)034016
R= B(D+→f0(980)e+νe)+B(D+→f0(500)e+νe) B(D+→a0(980)0e+νe)
R=1.0±0.3 for two-quark description; R=3.0±0.9 for tetraquark description.
We have R>2.7 @90% C.L. at BESIII Which favors the tetraquark description.
Decay BF (×10−4) Significance D0 → a0(980)−e+νe, a0(980)− → ηπ− 1.33+0.33
−0.29 ± 0.09
6.4σ D+ → a0(980)0e+νe, a0(980)0 → ηπ0 1.66+0.81
−0.66 ± 0.11
< 3.0 (90% C.L.) 2.9σ BESIII Semileptonic and leptonic charm decays at BESIII 19 / 26
Semileptonic D transitions into axial vector meson were predicted 30 years ago, but not experimentally confirmed yet. In theory, the predicted BFs are sensitive to K1 mixing angle(θK1) and its sign [PRD79(2009)036004, EPJC77(2017)369].
(GeV)
miss
U )
2
c (GeV/
π
+π
M (GeV)
miss
U )
2
c (GeV/
π
+π
M
(a) 1.0 1.2 1.4 1.6
0.00 0.05 0.10 (b)
)
2
c Events(/30 MeV/ 10 20 30 40
(c)
Events(/5 MeV) 10 20 30 1.0 1.2 1.4 1.6
5 χ
0.00 0.05 0.10
5 χ
(a)arXiv:1907.11370 B[D+ → ¯ K1(1270)0e+νe] = (2.30 ± 0.26 ± 0.18 ± 0.25) × 10−3
> 10σ
Our result indicates θK1 ∼ 33◦ or 57◦ and opens up opportunity to precisely study nature of ¯ K1(1270).
BESIII Semileptonic and leptonic charm decays at BESIII 20 / 26
c → Λℓ+νℓ
0.567 fb−1 data @4.6 GeV
0.1 0.2 10 20 30
0.1 0.2 10 20 30
PRL115(2015)221805
Λ+
c →Λe+νe
0.1 0.2 10 20 30
0.1 0.2 10 20 30
PLB767(2017)42
Λ+
c →Λµ+νµ
Previously expected: 1.4% → 9.2%. B(Λ+
c → Λe+νe) = (3.63 ± 0.38 ± 0.20)%
B(Λ+
c → Λµ+νµ) = (3.49 ± 0.46 ± 0.26)% Γ(Λ+
c →Λe+νe)
Γ(Λ+
c →Λµ+νµ) = 0.96 ± 0.16 ± 0.04
BESIII Semileptonic and leptonic charm decays at BESIII 21 / 26
c → Xe+νe
2.26 2.28 2.3 50 100 150 2.26 2.28 2.3 50 100 150
S
K p
2.26 2.28 2.3 200 400 600 800 2.26 2.28 2.3 200 400 600 800
+
K p
)
2
c / GeV (
BC
M )
2
c / MeV / (0.5 Events PRL121(2018)251801
) c Momentum (GeV/
0.2 0.4 0.6 0.8 1
) c Events / (0.1 GeV/
20 40 60
) c Momentum (GeV/
0.2 0.4 0.6 0.8 1
) c Events / (0.1 GeV/
20 40 60 Decay channel B (%) Model Λ+
c → Λe+νe
3.63 ± 0.43 F V
1 (q2) = 2.52 5.09−q2
Λ+
c → Λ(1405)e+νe
0.38 ± 0.38 pythia Λ+
c → ne+νe
0.27 ± 0.27 pythia Result Λ+
c → Xe+νe Γ(Λ+ c →Xe+νe) ¯ Γ(D→Xe+νe)
BESIII 3.95 ± 0.35 1.26 ± 0.12 MARK II 4.5 ± 1.7 1.44 ± 0.54 B(Λ+
c → Xe+νe) = (3.95 ± 0.34 ± 0.09)% B(Λ+ c →Λe+νe) B(Λ+ c →Xe+νe)
= (91.9 ± 12.5 ± 5.4)%
This ratio is predicted to be 1.67 using an effective-quark theory calculation 1.2 based on a calculation using the heavy-quark expansion.
BESIII Semileptonic and leptonic charm decays at BESIII 22 / 26
Not subject to helicity suppression. Only photon energy larger than 10 MeV are considered. The BFs are predicated to be
10−5→10−3 in various models.
c ¯ s e+ νe W γ c ¯ s e+ νe W γ c ¯ s e+ νe W γ c ¯ s e+ νe W γ c ¯ s e+ νe V γ
(GeV)
miss
U
0.1 0.2
Events/10 MeV
50 100 150
PRD95(2017)071102
D+→γe+νe D+→π0e+νe
❳❳ ❳ ③
B(D+ → γe+νe) < 3.0 × 10−5 @90% C.L.
0.1 0.2 0.3 5 10 15 20
data
e
ν
+
e η →
s
D
τ
ν
+
τ →
s
D MC
e
ν
+
e γ →
s
D
(GeV)
miss
U ) MeV Candidates / (10
PRD99(2019)072002
D+
s →γe+νe
B(D+
s → γe+νe) < 1.3 × 10−4 @90% C.L. BESIII Semileptonic and leptonic charm decays at BESIII 23 / 26
1 Precise measurement of decay constants, form factors and quark
mixing matrix elements → precision improved with BESIII measurement.
fD+|Vcd| ∼ 2.8% f D→K
+
(0)|Vcs| ∼ 0.6% fD+
s |Vcs| ∼ 2.0%
f D→π
+
(0)|Vcd| ∼ 1.4%
2 Lepton flavor universality test → no evidence of violation found in the
charm sector at the precision of 1.5% for CF decays and 4% for SCS decays.
3 The results of (a0(980)e+ν,f0(500)e+ν) favor the tetraquark
description.
4 First measurement of absolute branching fractions of semileptonic Λ+
c
decays.
5 Upcoming data at BESIII → more results to be expected.
BESIII Semileptonic and leptonic charm decays at BESIII 24 / 26
BESIII Semileptonic and leptonic charm decays at BESIII 25 / 26
)
2
(GeV/c
π K
m
0.6 0.8 1 1.2 1.4 1.6
2
Events / 0.02 GeV/c
1000 2000 3000 4000 5000
data fit bkg
+non-signal D combinatorial bkg
)
2
(GeV/c
π K
m
0.6 0.8 1 1.2 1.4 1.6
2
Events / 0.02 GeV/c
1 10
2
10
3
10
PRD94(2016)032001
)
4
/c
2
(GeV
2
q
0.2 0.4 0.6 0.8 1 1.2
4
/c
2
Events / 0.024 GeV
100 200 300 400 500 600
e
θ cos
1 − 0.5 − 0.5 1
Events / 0.04
100 200 300 400 500
K
θ cos
1 − 0.5 − 0.5 1
Events / 0.04
100 200 300 400 500 600
χ
3 − 2 − 1 − 1 2 3
π Events / 0.04
100 200 300 400 500
rV = V (0)/A1(0) = 1.411 ± 0.058 ± 0.007 r2 = A2(0)/A1(0) = 0.788 ± 0.042 ± 0.008 A1(0) = 0.589 ± 0.010 ± 0.012 Not included in the nominal fit: B(D+ → ¯ K∗(1410)0e+νe) (0 ± 0.009 ± 0.008)% < 0.028% (90% C.L.) B(D+ → ¯ K∗
2 (1430)0e+νe)
(0.011 ± 0.003 ± 0.007)% < 0.023% (90% C.L.) P( ¯ K∗(892)0) Simple Pole plus BW with mass-dependent width (3.54 ± 0.03 ± 0.08)% S( ¯ K∗
0 (1430)0 and non-resonant part)
LASS plus BW with mass-dependent width (0.228 ± 0.008 ± 0.008)% BESIII Semileptonic and leptonic charm decays at BESIII 26 / 26