Fundamental Symmetries

Satoshi MIHARA KEK/J-PARC

IUPAP WG.9 Nuclear Science Symposium, Tokyo 29/Aug/2017

Outline• Introduction

• Experimental “searches” for symmetry violations

• CP symmetry

• T symmetry

• Matter-antimatter balance

• Summary

Left-Right Symmetry

Photo from http://s-park.wao.ne.jp/archives/1443

Symmetries in particle physics

• Charge conjugation: C

• Parity inversion: P

• Time reversal: T

• I will try to summarize experimental quests to understand fundamental symmetries in particle/nuclear physics

• CP experiments & T experiments

CP Experiments

• Hadron experiments

• Neutrino experiments

Hadron

Kaon Experiments

• Indirect & Direct CP violations

AGS

KTeV

NA48

J-PARC KOTO Experiment• KL →π0νν̅

• Signature: 2γ+nothing

• Calorimeter and Hermetic veto detectors

• Kinematic feature (missing P)

• Reconstruct Zvtx and transverse momentum of π0

CP- CP+

KOTO Detector New photon veto installed

in April 2016

KOTO Detector New photon veto installed

in April 2016

K+ Experiments• BNL E787+E949

• Search for K+→π+νν̅

• Found 7 events

• BR = (1.73+1.15-1.05) ×10-10

Search for K+→π+νν̅ at NA62

with K+ ID

RICH particle ID

• 45 events/ year with 10 BG expectation

• Started 2016, runs in 2017 & 2018 to collect O(100) events

• http://www.lnf.infn.it/wg/vus/content/Krare.html Standard Model

by K+ decay →KL decay Isospin rotation

Standard Model• Br(K+→π+νν̅)=(8.22+0.74

-0.65±0.29)×10-11

• Br(KL→π0νν̅)=(2.57+0.38-0.36±0.04)×10-11

• Brod et al., 1009.0947

ρ

η

KL→π0νν̅K+→π+νν̅

Buras “Kaon Theory News”

Any deviation from the SM prediction is a sign of new physics

B Factory Experiments

•BaBar •Belle ( and Belle II ) •LHCb

• CP violations only in the kaon system before B factory Exps. started

• Hadronic uncertainties

• These uncertainties reduced thanks to much larger mass of B

• Numerous measurements of CP violation by Babar, Belle and LHCb

• And better precision in Belle II and future LHCb

CP violation at B factories

B̅0 B0

CP odd CP even

CP Violation in the baryon sector

• LHCb new result

• Λ0b , Λ̅0b

• 3.3σ deviation

• More statistics for confirmation

Nature DOI: 10.1038/NPHYS4021

Comparison of K and B Results

ρ

ηK

B

New Physics!T. Yamanaka

Neutrino

Long Baseline Neutrino Experiments

•T2K in Japan •NOvA in the US

T2K

NOvA

Neutrino CP• Mixing matrix in standard 3-neutrino mixing framework:

• Under the CP symmetry, we expect

Accessible through neutrino oscillations Majorana phases

Not same if δCP≠0

New Result from T2K• E-like observation vs. prediction

• Excess in neutrino mode (top)

• Deficit in anti-neutrino mode (bottom)

M. Hartz, KEK Colloquium, Aug 2017

New Result from T2K• Fit without the reactor constraint: closed contour in δCP at 90%CL

• Adding the reactor constraint improve the constraint on δCP

M. Hartz, KEK Colloquium, Aug 2017δCP=0, π outside of the 2σ CL intervals

Time Reversal

• Stringent limit by neutron EDM experiments

• Test of time reversal symmetry using polarized beam

Neutron EDM• Existence of EDM implies violation of Time Reversal Invariance

• Standard Model EDMs are due to CP phase in CKM, but extremely small → Sensitive to new physics!

• Current best limit: < 3.0×10-26 e・cm from ILL

Experimental Technique

• ILL-Grenoble experiment

• Trapped Ultra-Cold Neutrons (UCN) with NUCN = 0.5 UCN/cc

• |E| = 5 - 10 kV/cm

• 100 sec storage time

Harris et al. Phys. Rev. Lett. 82, 904 (1999)

Baker et al. Phys. Rev. Lett. 97, 131801 (2006) σd<3×10-26 e・cm

P. Schmidt-Wellenburg

Sensitivity to New Physics

Pendlebury & Hinds, NIMA 2000More nEDM results in near future!

P. Schmidt-Wellenburg

Time Reversal Test using Polarized Beam

• MTV at TRIUMF-ISAC, 8Li beam

• Test of time-reversal symmetry in polarized nuclear beta decay by measuring a triple correlation

• J: parent nuclear, σ: electron polarizations

• Electron polarization examined by utilizing the analyzing power of Mott scattering

• DAQ in progress in 2016-2017 to reach R≃O(10-4)

Matter-antimatter imbalance

Matter-antimatter imbalance

• Non-zero baryon number in the current universe

• The universe is made mainly of matter

• Sakharov conditions should be satisfied

• Violate baryon number symmetry

• Violate both C and CP symmetries

• Depart from thermal equilibrium

• Electroweak baryogengesis / Leptogenesis

PDG

Planck 2015

Leptogenesis

• How can we (experimentalist) confirm “Leptogenesis” ?

• M. Fukukita IPMU news

cLFV and MR

• Type-I SeesawR. Alonso et al, JHEP01 (2013)118

Br(μ→e)/Br(μ→eγ)

Br(μ→e)/Br(μ→eee)

Summary

• Fundamental symmetries have provided important information for us to understand the physics

• Understanding broken symmetries, or how the symmetry is broken, is more interesting than finding a new symmetry

Symmetry Breaking !

Symmetry Breaking !Cherry tree in Sion

Cherry tree in Nagano