The impact of heavy-quark loops on LHC dark matter searches

Transcription

1 KICP workshop: Dark maer a he LHC The impac of heavy-uark loops on LHC dark maer searches Universiy of Nore Dame KICP workshop: Dark maer a he LHC 19 h Sepember 2013 Mainly based on arxiv: wih Felix Kahlhoefer & Uli Haisch The impac of heavy-uark loops on LHC dark maer searches

2 KICP workshop: Dark maer a he LHC Effecive operaors As a firs sep, effecive operaors provide a simple paramerisaion for mono-j searches. Can wrie down dimension 5 and 6 operaors involvin uarks and fermion or scalar φ DM. Conac operaors arise from inerain ou some heavy mediaor sae, wih mass around scale Λ. Validiy of he EFT depends on he scales involved. For collider searches mediaor mass should be in excess of even level eneries few 100 GeV. The impac of heavy-uark loops on LHC dark maer searches

3 KICP workshop: Dark maer a he LHC Yukawa-like DM operaors Consider Laranian involvin SM sinle scalar η & fermion DM L = λ X η + µη H m2 ηη 2 + V(H) Expandin around he His VEV L = λ X η + y h+ 1 2 µη h ( η, h ) ( m 2 η µv µv m 2 h ) ( η h ) + Goin o mass eienbasis (η 1, h 1 ) iven in erms of a mixin anle θ η = cos θ η 1 + sin θ h 1, h = sin θ η 1 + cos θ h 1, L = λ X η 1 + λx θh µη 1h y h 1 y θ η 1 + V(H). Inerain ou η 1 ives he effecive operaor: yθλx m. 3 η The impac of heavy-uark loops on LHC dark maer searches

4 KICP workshop: Dark maer a he LHC Operaors of ineres We focus on he followin moivaed sub-class of operaors wih Yukawa srucure: The impac of heavy-uark loops on LHC dark maer searches

5 KICP workshop: Dark maer a he LHC Monoje/relic densiy consrains As cross secions for collider producion, direc deecion, and annihilaion ino SM fermions involve idenical couplins, in simple models of WIMP and asymmeric DM hey ive complemenary bounds on parameer space GeV 100 GeV Ψ : m s Ψ Ψ v Ψ 1 : Ψ 2 ΓΜ Ψ ΓΜ mdm GeV Solid lines: DD bounds, dashed: monoje limis, black line: relic densiy consrain. From arxiv: (March-Russell, JU, Wes, /w Alas 1fb 1 se), similar analyses see e..: Irvine roup , , Fermilab roup , , Chicao roup , Buckley mdm GeV Mono-j limis are much weaker for Yukawa coupled operaor, since for lih uarks hen m is small, whereas heavy uarks are PDF suppressed. The impac of heavy-uark loops on LHC dark maer searches

6 KICP workshop: Dark maer a he LHC His physics Tha loops can be imporan for Yukawa-like operaors can be seen from His Physics, as luon fusion is a leadin His producion channel. arxiv:hep-ph/ Djouadi Heavy op limi m works well for His physics as m h m. Analoous limi for DM scenario suess operaors like G a µνg a µν ; bu his does no accuraely capure he physics as he mediaor mus be heavy for ood EFT and ypically his overesimaes cross secion by facor O(10). The impac of heavy-uark loops on LHC dark maer searches

7 KICP workshop: Dark maer a he LHC Loop vs Tree wih Yukawa-like DM operaors Main effecs: Reducion compared o Tree level due o loop facor Gain by replacin m m wihou PDF suppression Ne impac? The impac of heavy-uark loops on LHC dark maer searches

8 KICP workshop: Dark maer a he LHC Loop vs Tree wih Yukawa-like DM operaors Usin FeynArs/FormCalc/LoopTools we derive he followin mono-j bounds from he 5 fb 1 search by CMS a s = 7 TeV wih /E T > 350 GeV m ΨΨ 3 s s GeV m p 3 ΨΓ5 Ψ Γ m s 2 Φ Φ p GeV 100 s GeV We do no include addiional jes, hadronisaion or showerin effecs (expeced o be small). The impac of heavy-uark loops on LHC dark maer searches

9 KICP workshop: Dark maer a he LHC Comparison wih direc deecion (fermion DM) For scalar Lorenz srucure: Treelevel bound Looplevel bound DAMA CoGeNT Xenon100 Xenon10 CDMSII Ge CDMSII Si Noe, new bound now in conflic wih DAMA and Coen sinal reions. For pseudoscalar here are essenially no direc deecion limis as he scaerin cross secion is momenum suppressed. The impac of heavy-uark loops on LHC dark maer searches

10 KICP workshop: Dark maer a he LHC Concludin remarks Exended NLO sudy of wider rane of operaors presened by Fox and Williams, arxiv: and see alk of Kahlhoefer (nex). Ede of validiy for EFT in many cases. Wih lih mediaors mass hresholds and resonances are imporan for monoje limis and also (relic densiy). Reuirin careful sudy and ypically more model dependen. Recenly, move owards simplified models: Frandsen e al , An e al , Chan e al , Bai & Berer , DiFranzo e al , Buchmueller e al (see Friday AM session) Summary: In he moivaed class of DM models where DM couples o SM fermions hrouh a Yukawa-like operaor includin loop effecs increases he producion cross secion wo orders of maniude! The impac of heavy-uark loops on LHC dark maer searches