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The Collider Phenomenology of Vectorlike Confinement. Can Kılıç , University of Texas at Austin work done with:Takemichi Okui (arXiv: 1001.4526, JHEP 1004:128, 2010 ) Takemichi Okui, Raman Sundrum (arXiv: 0906.0577, JHEP 1002:018, 2010) - PowerPoint PPT Presentation
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The Collider Phenomenology of Vectorlike Confinement
Can Kılıç, University of Texas at Austinwork done with: Takemichi Okui (arXiv: 1001.4526, JHEP 1004:128, 2010 ) Takemichi Okui, Raman Sundrum (arXiv: 0906.0577, JHEP 1002:018, 2010)
Steffen Schumann, Minho Son (arXiv: 0810.5542, JHEP 0904:128, 2009)Takemichi Okui, Raman Sundrum (arXiv: 0802.2568, JHEP 0807:038, 2008)
Introduction• The are well into the LHC era.
• We know that there must be new physics.
• Situation very different from previous experiments. No single compelling extension of SM.
• Tension for solutions to hierarchy problem from direct searches and precision data.
What Might Lie Ahead
MPlanck
vNew Physics
• The good (no-tuning):we just haven’t found the magic theory yet.
What Might Lie Ahead
MPlanck
v
New Physics
• The bad (severe fine-tuning)nothing to be seen at LHC except elementary Higgs boson.
What Might Lie Ahead
• The ugly (“meso-tuning”)• Look for low-mass tail
MPlanck
v
New Physics
LHC reach
A Different Angle• Meso-tuning: how to proceed?• We take the absence of low
energy signatures as a hint.• A simple module that can fit into
of bigger picture.• Theoretically generic• Signatures:
– discoverable?– distinguishable?
MPlanck
v
New Physics
LHC reach
Safe Strong Interactions• LHC Phenomenology of BSM physics
dominated by pair production / resonant production: many constraints
• Not all possibilities fully explored.• Strong interactions at TeV scale have been
associated with EW-breaking. Signatures very strongly influenced.
• Can there be safe low energy sector? • Analogy with sub-GeV e+ e- collider. Rich
phenomenology from a minimal theory.
Analogy in a Picture
Low Energy QCD – A Brief Review• Begin by strongest interactions (u,d only)• special because it is light. Guaranteed
by breaking of flavor symmetry.
• ρ special because it is the lightest meson that can be resonantly produced once we add electromagnetism. Decays to .
• ’s and baryons stable
Consequences of adding electromagnetism
(qu = 2/3 , qd = -1/3)• ρ/γ mixing• resonant production• charges• mass difference• Neutral can decay
Low Energy QCD – A Brief Review
• Both up and down number still conserved, charged so far stable, turn on weak interactions.
• Charged can now decay.• Need light particles for charged to
decay, introduce leptons: non-strongly interacting particles.
as well as neutron decay.• Proton still stable.
Low Energy QCD – A Brief Review
Could Lightning Strike Twice?From a simple UV theory to rich IR Physics
• Hypercolor: New fundamental interaction with scale ΛHC.
• “Hyper-pions” lightest. Guaranteed by breaking of flavor symmetry.
• Hyperpions and baryons stable at this point.• Hyper- ρ is the lightest hyper-meson that
can be resonantly produced, decays to 2
Could Lightning Strike Twice?From a simple UV theory to rich IR Physics
• Turn on SM interactions (weak+hypercharge)hyperfermions charged under SM.
• SM breaks many of the flavor numbers, introduce “species” of hyperfermions. (e.g. color triplet)
• Each SM gauge boson can mix with a , resonant production.
• charges (not only electromagnetic)• Radiative masses for• Anomaly of neutral pion decay can decay hyper-pion
with zero species number ( - short)• Species number unbroken. Leads to stable .
Could Lightning Strike Twice?From a simple UV theory to rich IR Physics
• - long stable, SM charged. • Introduce hyper-weak
interactions.• can now decay to a pair
of SM fermions (quark or lepton).
• Hyper-baryons can be stable or they can decay.
Recap
• For each SM gauge boson, there can be a , with mass ~ ΛHC.
• masses from radiative effects / EWSB / hyperquark masses. Produced through SM or through decay.
• either collider-stable or decay to pairs of SMGB
Attractive features
• Precedent• Flavor blind, therefore safe from low energy
searches. You don’t see new physics coming until you produce it directly.
• Dilepton / dijet resonance searches evaded.• Rich phenomenology: A minimal theory naturally
gives rise to an array of distinct collider signatures (multi-photons, CHAMPs, R-hadrons, multijets).
• Few free parameters.
Benchmark I: Without Color
• CHAMP and multi-photon production.• Spectrum: W’,Z’,B’ at ΛHC.
Benchmark I : Mass points
Benchmark I: CHAMP signal• Doubly charged scalar decays promptly to CHAMP, decay products
unobservable• several processes add to “CHAMP production”• Distributions
CHAMPs: Triggering• Production away from
threshold because of spin-1 intermediate state.
• Acceptance (||<2.5) over 90% for all mass points.
• Time lag to muon system.
CHAMPs: Bounds
CHAMPs: Prospects• Moderate β: TOF, dE/dx, curvature• High- β : Analysis by Adams et al. (arXiv: 0909.3157)
uses the fact that muons are no longer MIPs at these energies. (200 pb-1 at 10 TeV)
CHAMPs: VC Signatures
Can verify • spin-1 s-channel production• resonance
3γ+W: Final States• Production channels: +-,+0 or -0 (no 00, therefore no 4γ)• decays• also 2γ from (WZ)(γγ)(res) / (γZ)(γW) and (γW)(γW)(non-res) –
relevant for GMSB searches.• Since 3γ rate comparable, focus on the easier case.• Should be easy to distinguish from (fermiophobic) Higgs
3γ+W: BG• BG: Taking guidance out of h->γγ searches, we expect irreducible
BG to be O(1) fraction of total BG.• Scale up irreducible BG by x10. (MG γγ+jet(s) / Pythia / PGS)• Signal done with batch mode of CalcHep / Pythia / PGS• hard pT cut to reduce BG
3γ+W: BG• BG: Taking guidance out of h->γγ searches, we expect irreducible
BG to be O(1) fraction of total BG.• Scale up irreducible BG by x10. (MG γγ+jet(s) / Pythia / PGS)• Signal done with batch mode of CalcHep / Pythia / PGS• hard pT cut to reduce BG
3γ+W: BG• BG: Taking guidance out of h->γγ searches, we expect irreducible
BG to be O(1) fraction of total BG.• Scale up irreducible BG by x10. (MG γγ+jet(s) / Pythia / PGS)• Signal done with batch mode of CalcHep / Pythia / PGS• hard pT cut to reduce BG
3γ+W:• Use resonance mass from previous part• Define best W candidate
– for leptonic W, solve for neutrino rapidity, reconstruct scalar– for hadronic W, take pair (pT>20, ΔR<2) with 70GeV<mjj<90GeV
• Reconstruct ECM• Consistency check with CHAMP distribution
Benchmark II: With Color
• R-hadron and multi-jet production• Two resonances, g’ and B’.
Benchmark II: Mass Points
R-hadrons• Large cross section from QCD• Distributions• Effect of gg initial state• Hadronization, comparison to CHAMPs
R-hadrons: Triggering• Very similar kinematics to
CHAMPs, good triggering efficiency.
• Acceptance over 80% for all mass points.
R-hadrons: VC Signatures
• Evidence for g’ resonance• Smaller mass gap• 4 R-hadron production
Multi-jets: Tevatron• Signal dominantly from valence quark initial state,
background from gluons. 2 2 vs. 2 many• 4j with similar pT. Use pT1>120GeV for trigger, • 1fb-1 data, 2fb-1 bg• Cone jets, ΔR=0.7• For mg’=350GeV use pT4>40GeV, Δminv<25GeV• For mg’=600GeV use pT4>90GeV
Multi-jets: LHC• For mg’=750GeV use
pT4>150GeV, Δminv<50GeV (1fb-1 of data)
• For mg’=1.5TeV use pT4>250GeV (10 fb-1 of data)
• <2 for all partons, cone jets, ΔR=0.5
• Straightforward to discover scalar
• Sliding cut• g’ more tricky.
Multi-jets at the LHC: Bounds
Multi-jets: LHC (g’)
• Boldly go where no one has gone before: 8 jets.• Large cross section for g’ pair production.• Self-calibrating search: minv cuts from 4j, pT cuts from hT.• After pT cuts, signal and bg comparable.
Multi-jets: LHC (g’) Analysis• parton level truth – PGS level jet matching• Take 4 hardest jets, 4 more out of next 6.• All pairings, use result of 4j analysis• Plot mass of g’ candidates: signal accumulates• Background sanity check: cannot do 28 unweighted events, do 26 and
shower.• Cross-check with R-hadrons
Conclusions• VC: QCD-like theories with rich phenomenology, safe
from low energy precision tests.• Vector states can be resonantly produced, decay to
naturally light scalars.• Scalars have short-lived and collider stable species.
– Short-lived scalars decay to a pair of SM gauge bosons. – Long lived scalars appear as CHAMPs / R-hadrons.
• Benchmarks– without color: multi-photons, CHAMPs– with color: multi-jets, R-hadrons
• Kinematic reconstruction possible in all final states• Novel signatures: Resonances, 4 R-hadrons• Other possibilities: decay to fermions, cascades, DM
candidates
Backup Slides
Backup Slides
Backup Slides
Anomaly first in shape – then in normalization