for K π0νν¯ at KOTO experiment L · ¯ at KOTO experiment. 4 / 16. K. L → π. 0. νν ¯ and...

New physics implications of recent search for at KOTO experimentKL → π0νν

Teppei Kitahara Technion and Nagoya University (KMI)

TK, T.Okui, G.Perez, Y.Soreq, K.Tobioka, arXiv:1909.11111, Phys.Rev.LeK. in press

Probing BSM physics at different scales January 31, 2020, Magnus Haus, Berlin

KL → ππ

K0 → μ+μ− K → πνν

B physics RBC-UKQCD

FCNC and/or CPV

εK and ε′

KS → π0μ+μ−

KS → μ+μ−γKS → 4ℓKS → π+π−e+e−

Understanding of ChPT

KL → π0ℓ+ℓ−

Reduce th error

K → πX

vs unitarityVus

CORRELATION

K → πνν

Teppei Kitahara: Technion/Nagoya University, Probing BSM physics at different scales, January 31, 2020, BerlinNew physics implicaFons of recent search for at KOTO experimentKL → π0νν

/ 164

and KL → π0νν K+ → π+νν

Both channels are theoretical clean and significantly sensitive to short-

distance contributions, especially is purely CPV decay

SM predictions:

KL → π0νν

CKM from tree observables

[Buras, Buttazzo,Girrbach-Noe, Knegjens ’15]

s → dνν

Charm contribution ～50%Charm contribution ～ 0%

On-going experiments:

@CERN @J-PARC20 SM events are expected in 2016-18 runs

K+ KL SM event is expected in ~2024

CP-odd CP-even


/ 165

Strategy of KOTO experiment[Figures from Yamanaka-san@FPW2019]

All particles are invisible. One can observe only photon energy

Assuming pion mass, One can reconstruct the decay point and missing pT

Initial state is neutral long-lived particle = KL + neutron (+ ALP see later)

KOTO can not measure diphoton invariant mass


/ 166

Grossman-Nir bound

Grossman-Nir bound for general NP models (including ) νiνj

B�KL ! ⇡0⌫⌫

�=

⇣ ⌧L⌧+

+�IB,EM

⌘sin2 ✓B

�K+ ! ⇡+⌫⌫

� 4.32B

�K+ ! ⇡+⌫⌫

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[Grossman, Nir ’97]

s → dνν s → dννu

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u<latexit sha1_base64="ZnBVU8ewHTObkyLI/i3dgvP1Jzs=">AAAB7nicbVBNS8NAEJ3Ur1q/qh69LBbBU0lqQY9FLx4r2A9oQ9lsJ+3SzSbsboQS+iO8eFDEq7/Hm//GbZuDtj4YeLw3w8y8IBFcG9f9dgobm1vbO8Xd0t7+weFR+fikreNUMWyxWMSqG1CNgktsGW4EdhOFNAoEdoLJ3dzvPKHSPJaPZpqgH9GR5CFn1Fip0w+oytLZoFxxq+4CZJ14OalAjuag/NUfxiyNUBomqNY9z02Mn1FlOBM4K/VTjQllEzrCnqWSRqj9bHHujFxYZUjCWNmShizU3xMZjbSeRoHtjKgZ61VvLv7n9VIT3vgZl0lqULLlojAVxMRk/jsZcoXMiKkllClubyVsTBVlxiZUsiF4qy+vk3at6l1Vaw/1SuM2j6MIZ3AOl+DBNTTgHprQAgYTeIZXeHMS58V5dz6WrQUnnzmFP3A+fwCgt4/C</latexit>K0

L<latexit sha1_base64="8nCqRQkf423YCJQvxD3h8UyT7Yc=">AAAB7HicdVBNSwMxEM3Wr1q/qh69BIvgqSRVbHsrCCLooYLbFtq1ZNNsG5rNLklWKEt/gxcPinj1B3nz35htK6jog4HHezPMzPNjwbVB6MPJLS2vrK7l1wsbm1vbO8XdvZaOEkWZSyMRqY5PNBNcMtdwI1gnVoyEvmBtf3ye+e17pjSP5K2ZxMwLyVDygFNirORe9a/vUL9YQmWEEMYYZgRXz5Al9XqtgmsQZ5ZFCSzQ7Bffe4OIJiGThgqidRej2HgpUYZTwaaFXqJZTOiYDFnXUklCpr10duwUHlllAINI2ZIGztTvEykJtZ6Evu0MiRnp314m/uV1ExPUvJTLODFM0vmiIBHQRDD7HA64YtSIiSWEKm5vhXREFKHG5lOwIXx9Cv8nrUoZn5QrN6elxsUijjw4AIfgGGBQBQ1wCZrABRRw8ACewLMjnUfnxXmdt+acxcw++AHn7RNi6Y5u</latexit>

K�<latexit sha1_base64="AN6XFLUvNAYWerDVYV36Jia26ug=">AAAB6nicdVBNS0JBFL3Pvsy+rJZthiRok8xYpO6EIII2RmmCvmTeOOrgvA9m5gXy8Ce0aVFE235Ru/5N89Sgog5cOJxzL/fe40VSaIPxh5NZWFxaXsmu5tbWNza38ts7TR3GivEGC2WoWh7VXIqAN4wwkrcixanvSX7rjc5S//aeKy3C4MaMI+76dBCIvmDUWOn68u6omy/gIsaYEIJSQsqn2JJqtVIiFURSy6IAc9S7+fdOL2SxzwPDJNW6TXBk3IQqI5jkk1wn1jyibEQHvG1pQH2u3WR66gQdWKWH+qGyFRg0Vb9PJNTXeux7ttOnZqh/e6n4l9eOTb/iJiKIYsMDNlvUjyUyIUr/Rj2hODNybAllSthbERtSRZmx6eRsCF+fov9Js1Qkx8XS1Umhdj6PIwt7sA+HQKAMNbiAOjSAwQAe4AmeHek8Oi/O66w148xnduEHnLdPDwWNrA==</latexit>

⇡�<latexit sha1_base64="jpN8MSVcGZN1yotLy/oNj4i70Ew=">AAAB7HicdVBNS8NAEJ3Ur1q/qh69LBbBiyVJQ1tvBUE8VjCt0May2W7bpZtN2N0IpfQ3ePGgiFd/kDf/jZu2goo+GHi8N8PMvDDhTGnb/rByK6tr6xv5zcLW9s7uXnH/oKXiVBLqk5jH8jbEinImqK+Z5vQ2kRRHIaftcHyR+e17KhWLxY2eJDSI8FCwASNYG8nvJuzurFcs2eXzetX1qsgu23bNcZ2MuDWv4iHHKBlKsESzV3zv9mOSRlRowrFSHcdOdDDFUjPC6azQTRVNMBnjIe0YKnBEVTCdHztDJ0bpo0EsTQmN5ur3iSmOlJpEoemMsB6p314m/uV1Uj2oB1MmklRTQRaLBilHOkbZ56jPJCWaTwzBRDJzKyIjLDHRJp+CCeHrU/Q/abllp1J2r71S43IZRx6O4BhOwYEaNOAKmuADAQYP8ATPlrAerRfrddGas5Yzh/AD1tsn0aOOtg==</latexit>

⇡0<latexit sha1_base64="w1SNhTGYSBehceNGr3xcic7yQ9M=">AAAB7HicdVBNS8NAEN3Ur1q/qh69LBbBU9ikoa23giAeK5i20May2W7apZtN2N0IpfQ3ePGgiFd/kDf/jZu2goo+GHi8N8PMvDDlTGmEPqzC2vrG5lZxu7Szu7d/UD48aqskk4T6JOGJ7IZYUc4E9TXTnHZTSXEcctoJJ5e537mnUrFE3OppSoMYjwSLGMHaSH4/ZXdoUK4g+6JRc70aRDZCdcd1cuLWvaoHHaPkqIAVWoPye3+YkCymQhOOleo5KNXBDEvNCKfzUj9TNMVkgke0Z6jAMVXBbHHsHJ4ZZQijRJoSGi7U7xMzHCs1jUPTGWM9Vr+9XPzL62U6agQzJtJMU0GWi6KMQ53A/HM4ZJISzaeGYCKZuRWSMZaYaJNPyYTw9Sn8n7Rd26na7o1XaV6t4iiCE3AKzoED6qAJrkEL+IAABh7AE3i2hPVovVivy9aCtZo5Bj9gvX0C1i+OuQ==</latexit>

Same diagram in quark level

��KL ! ⇡0⌫⌫

�

� (K+ ! ⇡+⌫⌫)=

��pA⇡0⌫⌫ � qA⇡0⌫⌫

��2��p2A⇡0⌫⌫

��2=

1

4|1� �⇡⌫⌫ |2

=1

4(1 + |�⇡⌫⌫ |2 � 2Re�⇡⌫⌫) '

1

2(1� Re�⇡⌫⌫) = sin2

Arg (�⇡⌫⌫)

2

�

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/ 167

New result@KOTO[KOTO, KAON2019; 2016-18 data]

# of events 4 (3) Single event sensitivity 6.9×10-10

Expected BG 0.05±0.02Expected SM 0.05±0.01

B�KL ! ⇡0⌫⌫

�< 3.0⇥ 10�9 at 90%CL

<latexit sha1_base64="eRHjG+8cYOcEeYkYxMLupHFqIgc=">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</latexit>

[KOTO, PRL ‘19; 2015 data]

1 event of 4 signals is suspected as a BG from an upstream activity, but the remaining 3 events are quite distinct from presently known BGs

KOTO is planning to re-evaluate other BG sources/planning a special run for BG


/ 168

[TK, Okui, Perez, Soreq, Tobioka 1909.11111]Assuming the 3 events in KOTO data are signals

Statistics:

Only KL data (1d.o.f)

Best fit vs. SM ●

p-value ~ 10-4 ~ 3.8σ

KL—K+ plane (2d.o.f)

~ 3.4σBest fit vs. SM ●

NP on the GN bound (1d.o.f)

Best fit vs. Best NP ●

~ 2.1σ

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NA62

KOTO


/ 169

What do we learn?

NA62 is almost probing the SM signals. Great but no surprises.

KOTO result is about two orders of magnitude larger than the SM

[~3.8 (3.4) σ discrepancy]

If we consider general new physics that interacts with neutrinos

or stable and invisible new particles, the discrepancy can be

reduced to 2.1σ (red circle)

If the signals are true, the Grossman-Nir bound has to be broken

@CERN @J-PARC20 SM events are expected in 2016-18 runs

K+ KL SM event is expected in ~2024

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/ 1610

Heavy new physics

Heavy new physics can not violate the Grossman-Nir bound

Current data should be just statistical fluctuation

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O⌫⌫S,A =

⇥Q2

�12,�

i�Q1

⇤V�A

⇥L�12,�

i�L⇤V�A

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O⌫⌫D =

�d2d1

�V+A

(LL)V�A<latexit sha1_base64="So8+7q0E0ANq+cUPsgH/Rm790C4=">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</latexit>

C⌫⌫S,D � C⌫⌫

A ⇡ e�i 34⇡/(150TeV)2<latexit sha1_base64="xmsUbByh+/iee98hshWxnTef+ic=">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</latexit>

Currently no constraint.

Correlation with (or bound from) the other CPV rare decays:

BR(KL → π0ee) < 2.8 × 10−10 BR(KL → π0μμ) < 3.8 × 10−10BR(KS → μμ) < 2.4 × 10−10

[KTEV ‘04] [KTEV ’00][LHCb ’19]

[TK, Okui, Perez, Soreq, Tobioka 1909.11111]


/ 1611

Pion mass new physics: Minimal Higgs portal

SM + light CP-even singlet scalar, which mixes with the SM Higgs by sin θ[Egana-Ugrinovic, Homiller, Meade 1911.10203, Bhupal Dev, Mohapatra, Zhang 1911.12334]

yt × sin θ

2σ statistical fluctuation

Dashed-gray contour:

is practically stable

cτφ

φBR(φ → ee) ∼ 100 %

“ blind spot”π0

[Fuyuto, Hou, Kohda PRL ’15]

the constraint from is

significantly loosened by the

background of

K+ → π+νν

K+ → π+π0


/ 1612

Novel new physics interpretations

Heavy NP e.g.,

Light NP: KL → π0X, X → γγ

Pion mass NP:

Can explain 3 signals

still 2.1σ tension (on the GN bound)


O⌫⌫S = (Q2Q1)V�A(LL)V�A

<latexit sha1_base64="QpA7HvG/QHzQ6fEMRxDtZerVRuU=">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</latexit>

KL → π0Z′ , Z′ → νν, mZ′ ∼ mπ0

[Fuyuto, Hou, Kohda PRL ’15]

B�K+ ! ⇡+X

�< 5.6⇥ 10�8 at 90%CL, (mX = m⇡0)

<latexit sha1_base64="czT+9N8yC/WAG73pRZIfUVNliVg=">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</latexit>

[BNL-E949, ‘09]

“ blind spot” (NA62); π0 116 < mmiss < 152 MeV

Can explain 3 signals

New idea

Effectively go beyond the GN bound. Key: finite lifetime, detector difference → “lifetime gap” appears

consider CPV in s → dνν

The Grossman-Nir bound holds

Light NP: pAu: fixed target → a → γγ

Could explain 3 signals

New idea

ALP is produced at fixed target. Key: KOTO does not distinguish ,

mimics with missing pTmγγ

a → γγ π0 → γγ


/ 1613

Light new physics: KL → π0X, X → γγ

is rejected in the NA62 detectorK+ → π+X, X → γγ is long-lived in the KOTO detectorX

L = 150 m, E = 37 GeV

X (~CP even scalar) has finite lifetime and decays into diphoton

is CP-conserving process; CPV is not required in NP sectorKL → π0X

K+π+

γγ

KL

π0 → 2γ

XX

L = 3 m, E ~ 1.5 GeV

NA62 detetor KOTO detetor


B(K ! ⇡X)e�Lp

mXc⌧X

<latexit sha1_base64="9ezT7QJ16Rg2ppIdwXvdpUDvcOA=">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</latexit>

Suppression factor

0.01 0.050.10 0.50 1 5 10

10-8

10-5

0.01

�X [nsec]

suppressionfactor

KOTO

NA62

mX = 100 MeV

mX = 10 MeV

CP-odd CP-odd[Leutwyler, Shifman ’90]


/ 1614

Light new physics: KL → π0X, X → γγO(10)MeV is preferred in current datamX =


KOTO 3 events can be explain in white region

Models are investigated in Egana-Ugrinovic, Homiller, Meade 1911.10203; Liu, McGinnis, Wagner, Wang, 2001.06522

bound KL → π0γγ


/ 1615

ALP interpretation: pAu → a → γγALP (a) is produced at the fixed target and decays into in the KOTO detector

KOTO does not distinguish

γγ

mγγ

p30 GeV

Fixed terget = Gold (Au) γ

γ

a a

Lint =↵s

8⇡fgaGa

µ⌫Gaµ⌫ +↵EM

8⇡f�aFµ⌫ F

µ⌫

<latexit sha1_base64="QoHKPLDPQTY9ff1zVObp0Gh/+BA=">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</latexit>

Following parameter regions can explain KOTO O(1) events

ma ⇠ O(100)MeV < 3m⇡<latexit sha1_base64="5Y7OlCtlcsAuWyLQEKTxvy8ltrQ=">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</latexit>

fg ⇠ f� ⇠ O(1)TeV<latexit sha1_base64="AJWLvcGaxw14WXeyX69PQeA8c6g=">AAACHHicbVDLSitBEO3xbXxFXbppDIKChBkVdCm6uTsVTBQyYajp1MTG7pmhu+Zyw5APceOvuHFxRdy4EPwbO4+FrwMNp8+poqpOnCtpyfffvYnJqemZ2bn5ysLi0vJKdXWtabPCCGyITGXmOgaLSqbYIEkKr3ODoGOFV/Ht6cC/+ovGyiy9pF6ObQ3dVCZSADkpqu4nUZeHVmqeRGEXtIbRL9RANwJUedbfDnbC3ZDwHxldXmKzH1Vrft0fgv8kwZjU2BjnUfU17GSi0JiSUGBtK/BzapdgSAqF/UpYWMxB3EIXW46moNG2y+Fxfb7llA5PMuNeSnyofu4oQVvb07GrHOxsv3sD8TevVVBy1C5lmheEqRgNSgrFKeODpHhHGhSkeo6AMNLtysUNGBDk8qy4EILvJ/8kzb16sF/fuzioHZ+M45hjG2yTbbOAHbJj9oedswYT7I49sP/sybv3Hr1n72VUOuGNe9bZF3hvH/4RoVU=</latexit>

sin2 ✓a⇡ ⇠ 10�9<latexit sha1_base64="ActVtlMEkdKfptpfFpM0u1uJumo=">AAACC3icbVA9SwNBEN2LXzF+nVraLAmCjeEuCmoXtLGMYD4gdwl7m02yZG/v2J0TwpHexr9iY6GIrX/Azn/jJrlCEx8MPN6bYWZeEAuuwXG+rdzK6tr6Rn6zsLW9s7tn7x80dJQoyuo0EpFqBUQzwSWrAwfBWrFiJAwEawajm6nffGBK80jewzhmfkgGkvc5JWCkrl30NJedCvZgyIB0U4K9mE+wUUPsOp309GrStUtO2ZkBLxM3IyWUoda1v7xeRJOQSaCCaN12nRj8lCjgVLBJwUs0iwkdkQFrGypJyLSfzn6Z4GOj9HA/UqYk4Jn6eyIlodbjMDCdIYGhXvSm4n9eO4H+pZ9yGSfAJJ0v6icCQ4SnweAeV4yCGBtCqOLmVkyHRBEKJr6CCcFdfHmZNCpl96xcuTsvVa+zOPLoCBXRCXLRBaqiW1RDdUTRI3pGr+jNerJerHfrY96as7KZQ/QH1ucPLpWZ2g==</latexit>

KOTO setup

d = 27 m

⌧a ⇠ O(1) nsec<latexit sha1_base64="GY6us1XoUOt+6u8YJVxMkDMR/9A=">AAACEnicbVA9SwNBEN3z2/gVtbRZDIKChLsoaCna2KlgVMiFMLeZ6OLu3rE7J4Yjv8HGv2JjoYitlZ3/xk1M4deDgcd7M8zMSzIlHYXhRzAyOjY+MTk1XZqZnZtfKC8unbk0twLrIlWpvUjAoZIG6yRJ4UVmEXSi8Dy5Puj75zdonUzNKXUzbGq4NLIjBZCXWuWNmCBvAY+d1DzWQFcCVHHUW4+8g7dkdRFvGoei1ypXwmo4AP9LoiGpsCGOW+X3uJ2KXKMhocC5RhRm1CzAkhQKe6U4d5iBuIZLbHhqQKNrFoOXenzNK23eSa0vQ3ygfp8oQDvX1Ynv7B/tfnt98T+vkVNnt1lIk+WERnwt6uSKU8r7+fC2tChIdT0BYaW/lYsrsCDIp1jyIUS/X/5LzmrVaKtaO9mu7O0P45hiK2yVrbOI7bA9dsiOWZ0Jdsce2BN7Du6Dx+AleP1qHQmGM8vsB4K3TxJBnbw=</latexit>

production π→a decay a→γγ



/ 1616

Summary

Interesting preliminary data was announced by KOTO experiment. If it is true, it should be

a signal of new physics

Although the Grossman-Nir bound sets the upper bound on , several

new physics can avoid it practically

100 TeV new physics with statistical fluctuation

“ blind spot”

New light scalar using “lifetime gap”

Would be ALP

BR(KL → π0 inv.)

π0


/ 1617

New result@NA62

[NA62, KAON2019; 2016+17 data]

# of events 3Single event sensitivity (0.346±0.017)×10-10

Expected BG 1.65±0.31Expected SM 2.4±0.3

B�K+ ! ⇡+⌫⌫

�< 11(14)⇥ 10�10 at 90(95)%CL

<latexit sha1_base64="Vw2Us2xXhi47Fj3BlomUYTpCIHM=">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</latexit>

B�K+ ! ⇡+⌫⌫

�< 1.85(2.44)⇥ 10�10 at 90(95)%CL

<latexit sha1_base64="ESA8bRs2O9BkBBCU/JsQD2krTuA=">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</latexit>

Factor 6 improved

B�K+ ! ⇡+⌫⌫

�= 0.47+0.72

�0.47 ⇥ 10�10<latexit sha1_base64="7zzEyJZt7p2ZUvJiHdeb4nrCdy4=">AAACUnicbVJNSysxFE3rx9P6VX1LN8EiKOKQqULdPBDfRnCjYFXo1JJJM21oJhmSO+9RwvzGBw83/hA3LtRM24VfFwLnnntubnKSOJPCAiGPlerc/MLij6Xl2srq2vpGfXPrxurcMN5mWmpzF1PLpVC8DQIkv8sMp2ks+W08+l3Wb/9wY4VW1zDOeDelAyUSwSh4qlcXUUphyKh0Z0UkeQJ7F/fuoMCREYMhUGP0XxxlYsqpHEfa71YOcz4rpqr9XyQ4bnkJCVrNoucOy9TLQaTc4pDcu8OQFL16gwRkEvgrCGeggWZx2av/j/qa5SlXwCS1thOSDLqOGhBM8qIW5ZZnlI3ogHc8VNRP67qJJQXe9UwfJ9r4pQBP2PcdjqbWjtPYK0sD7OdaSX5X6+SQnHSdUFkOXLHpoCSXGDQu/cV9YTgDOfaAMiP8WTEbUkMZ+FeoeRPCz1f+Cm6aQXgUNK+OG6dnMzuW0DbaQXsoRC10is7RJWojhv6hJ/SCXisPleeq/yVTabUy6/mJPkR19Q0q8bKJ</latexit>

[NA62, FPCP2018; 2016 data]

B�K+ ! ⇡+⌫⌫

�< 3.35⇥ 10�10 at 90%CL

<latexit sha1_base64="KgiW2h9daUA7TYvZzIFkso3w0ik=">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</latexit>

[BNL-E949, ‘09]


/ 1618

ValidationsDistribution of signal π0ννWe simulated efficiencies difference between and

signal, which is consistent with KOTO analysis

π0νν

π0X

[KOTO, Phys. Rev. Lett. 122, 021802 (2019)]

Our MCKOTO signal region

z[mm]

pπ0

T[M

eV]



/ 1619

A simple idea, but does not work

Very simple idea of breaking the Grossman-Nir bound is just kinematics:

mK± = 493.6 MeV

mKL= 497.6 MeV

mπ± = 139.5 MeV

mπ0 = 134.9 MeV

(Mass difference comes from the radiative corrections within the SM)

Δm = 354.1 MeV

Δm = 362.7 MeV

has a larger phase space than

Can new 360 MeV particle explain signals? → Impossible

Emitted is too soft, the missing pT can not become large

KL → π0 K+ → π+

π0

Predicted signal region [Fabbrichesi, Gabrielli, 1911.03755]

for K π0νν¯ at KOTO experiment L · ¯ at KOTO experiment. 4 / 16. K. L → π. 0. νν ¯ and...

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Transcript of for K π0νν¯ at KOTO experiment L · ¯ at KOTO experiment. 4 / 16. K. L → π. 0. νν ¯ and...