The e+e- collider experiments to search for dark matter CosPA 2015 KAIST, Daejeon, Korea October 12 ~ 16, 2015 The e+e- collider experiments to search for dark matter Kihyeon CHO (KISTI)

Contents Introduction Search for dark matter at e+e- collider Summary

Introduction

Notation Dark photon =A’ = A = AD = U-boson Dark higgs - h’=h0 = HD … Heavy photon Dark force Light dark gauge boson =A’ = A = AD = U-boson Dark higgs - h’=h0 = HD … Kinetic mixing 2 = 2 = 2 = ’/

Dark sector constant Dark sector D = ’ = gD2 /4 Hidden sector Secluded sector …

Dark Matter A’ decay to DM Two body decay Upsilon decay  Eassig, et al, JHEP 11, 167 (2013).  Eassig, ArXiv: 1309.5084 [hep-ph] Neutral under SU(3)XSU(2)XU(1) Two body decay Upsilon decay One photon + missing ET

e+e- collider Enormous increases in luminosity over last few decays. ~ 2017

e+e- collider experiments CM Energy(GeV) Date Place 1. KLOE 1.02 2001~ INFN, Italy 2. BES III 3.78 2007~ Beijing, China 3. BaBar 10.58 1999~2008 SLAC, USA 4. Belle 1999~2010 KEK, Japan 5. Belle II 2017~

Search for Dark Matter at e+e- collider 9

Experiment vs. Dark Sector Dark Matter Dark photon Higg-Strahlung Heavy flavor lepton 1. KLOE 2 charged lepton+one photon 2 charged lepton +  + missing ET(h’) 2. BES III 3. BaBar one photon + missing ET 2 charge tracks + one photon 3 charged track pairs 4 or more charged tracks 4. Belle 2 charge track + one photon Two lepton pairs A lepton pairs + missing ET 5. Belle II 2 Charge Track one photon

1. KLOE Experiment Physics Program - Kaon physics, Spectroscopy, hadron cross-section,  physics, Dark sector

Dark Photon (1/3) ArXiv: 0903.0363 [hep-ph]

Dark Photon (2/3) Dark Photon (e+e-) Dark photon (e+e-  & +-) ArXiv: 1501.05517 [hep-ex]

Dark Photon (3/3) ArXiv: 1501.05517 [hep-ex]

Higgs-Strahlung + missing ET(h’) If Mh’ < MA’ - h’ long-lived invisible invisible ArXiv: 1501.05517 [hep-ex]

2. BES III Experiment Zhiyong Wang (2015)

Dark Photon Zhiyong Wang (2015)

Zhiyong Wang (2015)

Zhiyong Wang (2015)

3. BaBar Experiment A. Lusiani (2014)

Dark Matter (1/2) One photon + missing ET A. Lusiani (2014)

Dark Matter (2/2) One photon + missing ET A. Lusiani (2014)

Dark Photon one photon +  The effective Yukawa coupling (fY) of the b quark to the A0 A. Lusiani (2014)

Higgs-Strahlung A. Lusiani (2014)

4. Belle Experiment KEK

Higgs-Strahlung (1/4) h’ decays depending on Mh’ and MA’ . To measure the coupling constant of the dark photon to the dark higgs, D (1) Mh’ > 2MA’ : h’ → A’A’, very low background Exclusive: 3 charged track pairs with same invariant mass and total energy of event Inclusive: 2 charged track pairs, same invariant mass, third A from 4 mom. of e+e- system (2) MA’ < Mh’ < 2MA’: h’ → A’A’* (3) Mh’ < MA’ : h’ long-lived and h’ → l+l-, π+π- Mh’ (1) Mh’=2MA’ h’ → A’A’ (2) Mh’=MA’ h’ → A’A’* (3) h’ → l+l-, π+π- MA’ ArXiv: 0903.0363 [hep-ph]

Higgs-Strahlung (2/4) Case (1) Mh’ > 2MA’ : h’ → A’A’, Prompt of h’ and A’ 10 exclusive channels: 3(l+l-), 2(l+l-)(π+π-), 2(π+π-) (l+l-), 3(π+π-) with l=e, 3 inclusive channels: 2(l+l-)X with X dark photon (Missing mass)

Higgs-Starahlung (3/4) Background vs. number of events observed Dark photon Dark higgs Background vs. number of events observed BG: SM 2 processes with  or  final state Discontinuity at 1.1GeV due to selection criteria

Higgs-Strahlung (4/4) Dark photon and Dark higgs distributions

Dark Photon Dark photon decays SM particles. To call a “long-lived gauge boson” instead of dark photon Same analysis for Higgs-Strahlung work in progress Gianluca Inguglia (2015)

A’ couples only to heavy-flavor leptons Brian Shuv and Itai Yavin (arXive: 1403.2727[hep-ph]) If MA’ > 2M If MA’ < M or sterile neutrinos work in progress at Belle

5. Belle II Experiment

Dark Matter Dark photon decays DM. One photon + missing ET Full luminosity of 50 ab-1 and 1% trigger fraction Need a single photon trigger at Belle II Eassig, et al, JHEP 11, 167 (2013).

Dark photon Belle and Belle II detection efficiency for Eassig, et al, JHEP 11, 167 (2013).

Summary The e+e- collider experiments (KLOE, BESIII, BaBar, Belle) contribute to search for light Dark Matter particles. Belle II will search for Dark Matter in radiative decays with the trigger. With 50 ab-1, Belle II may also cross-check any signals discovered by fixed target experiments.

Beyond the Standard Model Standard Model Particles ⇒ Still going Dark Matter

Thank you.

Acknowledgement Youngjoon Kwon Patrick Fox Chaehyun Yu Soo-hyeon Nam Jangho Kim J. Cooley Rouven Essig K.Y. Choi