This document discusses searches for new physics in leptonic final states. It summarizes recent work on defining lepton jets, simulating new strong sector signals, and identifying analyses that could improve experimental sensitivity. These include tuning selection criteria for benchmark signals, separating electron from QCD jets, and measuring J/Psi production to search for new phenomena at existing experiments before the LHC startup.

1. Boost09
Leptonic Final States
Closing Remarks
Roger Moore, Itay Yavin, Josh Ruderman,
Natalia Toro, Philip Schuster, Andy, Haas,
Jay Wacker, Mariangela Lisanti
w/ non-local input from Yura Gershtein

2. Production modes
Lepton Jet + SM Jet
Jet + Dark DY
2 lepton Jets (+ MET) (+SM Jets)
Susy LSP to dark sector
Z/Z’ to dark particles
Direct dark particle production
Lepton Jet + (Photon/Iso Leptons)
(Shih &Thomas to appear)

3. Two-Lepton Lepton Jets
2 oppositely signed leptons in a small cone
Need more handles to get away from backgrounds
Flavor universal
+ − Heavy Flavor dominated
+ − + −
Ad
0 0
0 a a
χA!
0
h
χ0
SM
Higgs-like
Susy-like
ditau identification ?

4. 4-lepton lepton jet (single core)
Decay Topology
Relevant Parameters
pT φ1
φ2
mφ1 mφ2
φ2
cτφ! cτφ2
φ1
∆RSignal < 0.1
cτφ!
∼
0.1 < ∆RIso < 0.4
∼ ∼
Had Iso vs EM Iso
cτφ2

5. Usefulness/Danger of invariant masses
Taking pairwise invariant masses, total invariant mass
Gets away from SM continuum backgorund
But may be multiple resonances &/or missing particles

6. #'
σ [mb]
Additional Radiation
!"
#& J. Ruderman (to appear)
!"
Challenge with Isolation
#%
!"
#$
!"
! !"
)
Υ
!" J/ψ ψ(2S)
Motivates studying Had Iso vs EM Iso
*
!"
φ
ω
R
!"
ρ
Caveats for mφ > 700 MeV
∼
!
Combinatorics could hurt sensitivity
ρ
#!
!"
! !"

7. New Strong Sectors
High multiplicity final states
+
−
+
Light mesons
ωD ηD − √
ωD s ΛD
23-4/"5-&)")'&
0/-(*5506")'!-7')&
!"#$%&'()*#
&+*,'#-. qD
+"!#*/01")0*/
√
s ΛD
p
−
e p+
e #*89+5:-&;+'#0("5-
'<'/)
¯
qD
γ
mA ΛD
ωD
+ ωD ωD Lepton Jets
=**&)'!-;#*!8()&-
#'(*05-*>>-;+*)*/
−
− ηD
+ − + ωD

8. Other preliminary techniques/definitions
Multicore lepton jets (muon only)
General technique for collimated muons
Loosening isolation for high multiplicity muon jets
Nµ ≥ 4 ??
ET had <
∼ pT µ

9. New Tools
New Strong Signal Simulation
(J. Wacker w/ S. Schumann, P. Richardson, F. Krauss)
Dark Showering
Sherpa & Herwig
Hadron Spectrum
DarkSpecGen Dark Hadronization
Sherpa & Herwig
Cascading to SM
DarkSpecGen

10. Advances to improve theoretical prediction
Showering & Hadronization
(Abelian & Non-Abelian)
Parameterization/Categorization of Lepton jets &
Production modes for benchmarks
Implementation of benchmarks into MCs
highlighting sensitivity differences between
Tevatron/LHC/B-factories/Fixed Target/LHCb

11. Advances to improve experimental sensitivity
Tuning selection criteria to
improve sensitivity of benchmark
4-lepton lepton jet parameterization
Separating electron lepton jets from EM rich QCD jets
Mixed 2mu+2e lepton jet study
Hadronic isolation to prevent losses from
additional dark radiation
Scanning for di-mu resonances in hadronic events (Zurek & Gershetin)

12. Late Tevatron/LEP or Early LHC
Analyses and Measurements
Measuring J/Psi production & pT spectrum
Rate of muons from in-flight decays
Measuring resolution/efficiency at small
separation

13. Summary
Still making operative definitions of lepton Jets
New signals + tools appearing
Important searches to be done at Tevatron
Early searches possible at LHC
B-Physics & Fixed Targets Experiments
SLAC Workshop on Dark Forces: Sept 24-26, 2009