Masato Yamanaka (Tokyo university, ICRR) Collaborators Shigeki Matsumoto Joe Sato Masato Senami PHYSICAL REVIEW D 80, (2009)

Introduction Universal Extra Dimension (UED) model Model discrimination at LHC Motivation

Minimal Universal Extra Dimension (MUED) model [ Appelquist, Cheng, Dobrescu PRD67 (2000) ] 5-dimensions All SM particles propagate in spatial extra dimension (time 1 + space 4) R 4D spacetime S 1 New parameters in UED models R : compactification scale of extra dimension  cutoff scale of UED model S /Z orbifolding 2 1

Minimal Universal Extra Dimension (MUED) model [ Appelquist, Cheng, Dobrescu PRD67 (2000) ] 5-dimensions All SM particles propagate in spatial extra dimension (time 1 + space 4) R 4D spacetime S 1 S /Z orbifolding 2 1 Many Kaluza-Klein (KK) particles for one SM particle  SM particle  KK particle (1)(2),, ……, (n) Mass spectrum 1/R, 2/R, …..…, n/R (0)

Model discrimination at LHC proton g (1) q q Z l l  Missing energy q l MUED collider event

Model discrimination at LHC proton g q q Zl l  Missing energy q l proton g (1) q q Z l l  Missing energy q l ~ ~ ~~~ MUED collider event SUSY collider event Quite similar and difficult to discriminate !

Model discrimination at LHC  Supersymmetric particleSM particle SUSY MUED  SM particle  KK particle (1)(2),, ……, (n) ～

Model discrimination at LHC  Supersymmetric particleSM particle SUSY MUED  SM particle  KK particle (1)(2),, ……, (n) ～ (2) (0) f f V Second KK particle can couple with SM particles directly [ Datta, Kong, Matchev PRD72 (2005) ] [ Cheng, Matchev, Schmaltz PRD66 (2002) ] Mass reconstruction from dilepton clean signal Second KK photon (Z boson) decay into dilepton

Motivation Precise calculation of production rate of and  (2) Z Connecting our prediction to LHC data Discrimination between models and confirmation UED

and production KK number violating operator Production process  (2) Z

(0) f f V KK number violating operator All loop diagrams KK number violating vertices (gauge interaction) KK number violating vertices (Yukawa interaction)

KK number violating operator (2) (0) f f V

KK number violating operator (2) (0) f f V Significant advantages of the operator Production of, Z without kinematic suppression  (2) Clean mass reconstruction of and Z  (2)

Production through the KK number conserving processes Advantage ・ No loop suppression Disadvantage ・ Kinematic suppression due to pair production of second KK particles

Production through the KK number violating processes Advantage ・ Evading the phase space suppression Disadvantage ・ Loop factor suppression

Numerical result

Total production rate For integrated luminosity 100 fb 1 production  (2) ( For 400 GeV – 2000 GeV )

Discussion : significance of each process (1) Without kinematic suppression (2) and are directly produced  (2) Z Large contribution to the total cross section, particularly for large 1/R

Dilepton signal For integrated luminosity 100 fb 1

Summary and are the key ingredients for the discrimination  (2) Z (0) f f V It can be difficult to discriminate MUED model from other models We calculated the KK number violating operator We calculated the production rate of and  (2) Z Our prediction make it possible to the model discrimination and confirmation of the MUED model

Appendix

Universal Extra Dimension (UED) model 3 families from anomaly cancellation [ Dobrescu, Poppitz PRL 68 (2001) ] Preventing rapid proton decay from non-renormalizable operators [ Appelquist, Dobrescu, Ponton, Yee PRL 87 (2001) ] [ Servant, Tait NPB 650 (2003) ] Existence of dark matter Explaining cosmic ray excess anomaly [ Appelquist, Cheng, Dobrescu PRD67 (2000) ] [ J. Chang et al. Nature 456 (2008) ]

[ Datta, Kong, Matchev PRD72 (2005) ] Example of mass spectrum

Discussion : significance of each process (1) Dominant component of Parton distribution function of proton u-quark, d-quark, gluon Reason why these processes have large cross section (2) Logarithm factor prevents the drastic decreasing of cross section

Summary Observation of first KK particles Speculation of the value of 1/R Observation of second KK particles through di-lepton Determination of the mass of  (2) ( Z ) Mass of ( ) = Calculated mass from speculated 1/R  (2) Z Confirmation of the second KK particles ! Confirmation of the MUED model !!  (2) ( Z )