Monojet / monophoton / diphoton events with large missing transverse energy at the LHC Kang Young Lee GNU, SNU

Based on Sanghyeon Chang, Kang Young Lee, Jeonghyeon Song, Phys. Lett. B 717, 193 (2012).

Outlines Introduction Monojet events with large missing E T Monophoton events with large missing E T Diphoton events with large missing E T 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 E T signature. Monojet / monophoton events recoiling against nothing (large missing E T ) are the simplest and the most striking signatures for many extensions of the SM. Diphoton events with large missing E T 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 : p T (1) > 120 GeV, |η(1)| < 2.0 p T (2) < 30 GeV, |η(2)| < 4.5 HighPt : p T (1) > 250 GeV, |η(1)| 0.5 p T (2) < 60 GeV, |η(2)| < 4.5, p T (3) < 30 GeV E T (miss) > 120 GeV CMS E T (miss) > 150 GeV p T (1) > 110 GeV, |η(1)| < 2.4 N(jet) 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~(g NP v/M NP ) 2 CMS, PRL 107, (2011) Friedland et al., PLB 714, 267 (2012)

90% C.L. upper limits of 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, (2012)

ADD (monophoton) CMS, PRL 108, (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 E T. 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, (2011)

Summary Monojet / monophoton events with large missing E T are one of the best laboratory to test new physics scenarios beyond the SM. Diphoton events events with large missing E T can probe the Bino NLSP / gravitino LSP scenario in the GMSB model. Diphoton events events with large missing E T can also probe the Bino NLSP / axino LSP scenario in the MSSM and we obtained improved bounds on f a and Bino mass from the past experiment and the present LHC data. Bounds on f a -Bino mass depend on the lifetime measurement of the Bino, and consequently the detailed experimmental analysis method.

Thank you!

Dark matter