Monojet / monophoton / diphoton events

with large missing transverse energy

at the LHC

Kang Young LeeGNU , Jinju

@ SNU 2012.10.20

Based on

Sanghyeon Chang, Kang Young Lee, Jeonghyeon Song,

Phys. Lett. B 717, 193 (2012).

Outlines

• Introduction

• Monojet events with large missing ET

• Monophoton events with large missing ET

• Diphoton events with large missing ET

• Probing axino LSP from diphoton events

• Summary

Introduction

• Many new physics models beyond the SM contain invisible ingredients which can be produced at the LHC.

• “Invisible” denotes “weakly interacting to escape the detector” and leaves large missing ET signature.

• Monojet / monophoton events recoiling against nothing (large missing ET) are the simplest and the most striking signatures for many extensions of the SM.

• Diphoton events with large missing ET are an good probe to the Bino NLSP in the SUSY models. We probe axino LSP w/ Bino NLSP SUSY model by the diphoton data.

Monojet / Monophoton

SM processes

Event selections (monojet)

ATLAS LowPt : pT(1) > 120 GeV, |η(1)| < 2.0 pT(2) < 30 GeV, |η(2)| < 4.5 HighPt : pT(1) > 250 GeV, |η(1)| < 2.0, ΔΦ(j2,Emiss) > 0.5 pT(2) < 60 GeV, |η(2)| < 4.5, pT(3) < 30 GeV ET(miss) > 120 GeV CMS ET(miss) > 150 GeV pT(1) > 110 GeV, |η(1)| < 2.4 N(jet) <=2, jet with pT > 30 GeV ΔΦ(j1,j2) > 2.0 Lepton removal

Possible new physics

• Large extra dimensions

• SUSY

• Dark matter in association with a jet

• Unparticle

• Leptoquark, Z’ etc.

ADD and unparticles

qqbar → gG (gU), qg → qG (qU), gg → gG (gU)

SUSY monojet

SUSY monophoton

leptoquark

Z’

Dark matter

ADD (monojet)

ATLAS, PLB 705, 294 (2011)

unparticle

Z’

ε~(gNPv/MNP)2

CMS, PRL 107, 201804 (2011)

Friedland et al., PLB 714, 267 (2012)

90% C.L. upper limitsof the χ-nucleon scattering cross section

These are interpretation of the LHC results to be compared with the DM direct detection results

Dark matter (monophoton)

CMS, PRL 108, 261803 (2012)

ADD (monophoton)

CMS, PRL 108, 261803 (2012)

Diphoton

• Bino NLSP / gravitino LSP in the GMSB model

• SUSY particles → Binos → gravitino + photon

• All the SUSY final states are two photons and large missing ET.

• It can apply to Bino NLSP / axino LSP model.

• Bino lifetime measurement is essential.

Before LHC

Axion

Dynamical solution of the strong CP problem

For the details, please ask to E. J. Chun…

Axion supermultiplet + MSSM

At the LHC

ATLAS, EPJC 71, 1744 (2011)

CMS, PRL 106, 211802 (2011)

Summary

• Monojet / monophoton events with large missing ET are one of the best laboratory to test new physics scenarios beyond the SM.

• Diphoton events events with large missing ET can probe the Bino NLSP / gravitino LSP scenario in the GMSB model.

• Diphoton events events with large missing ET can also probe the Bino NLSP / axino LSP scenario in the MSSM and we obtained improved bounds on fa and Bino mass from the past experiment and the present LHC data.

• Bounds on fa-Bino mass depend on the lifetime measurement of the Bino, and consequently the detailed experimmental analysis method.

Thank you!

Dark matter