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1 Heidelberg 2009 Non-minimal models and their challenges for the LHC Matthew Strassler Rutgers University.

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1 1 Heidelberg 2009 Non-minimal models and their challenges for the LHC Matthew Strassler Rutgers University

2 2 The bias of minimalism One of the greatest threats to progress in science is bias. Therefore important to search for and eliminate sources of bias. Minimal models that solve a theoretical problem are elegant. The love of elegance is a bias.  Nature has not been elegant so far  Should we expect elegance at the LHC? As a result of this bias, we have largely ignored non-minimal models. This is extremely dangerous. Effects on LHC pheno can be drastic! But there is still time.

3 3 Theory vs. Experiment A large change to a theory may be a small change to an experiment  Minimal SUSY vs UED A small change to a theory may be a large change to an experiment  Add one real scalar field to the Higgs sector of SM: 2 Higgs bosons h, H  h  bb, tau tau, H  WW,ZZ Or 2 Higgs bosons h, H  h  bb, tau tau, H  hh Or one invisible Higgs boson  SUSY + one new (s)particle not at all like MSUGRA! Lose 50% of MET? Soft jets? What if I add two, or three, or… Very easily end up with largely or completely new signatures

4 4 This Talk – Pure Chaos 04 /06 Zurek and I have gone hiking and gotten lost in hidden valleys 06 /08 Kang and Luty have become very quirky lately 07 Georgi, Terning and others have stopped doing particle physics We are all looking at interesting dynamics in new hidden gauge sectors A lot of weird signatures have been uncovered which  are completely reasonable, but  have not been considered enough, or at all, by hadron collider experiments Note “effective” Lagrangians, mass reconstruction methods can fail here Motivation  Experimental: must not miss any signals of new physics!  Theoretical: not the point… but string theory, SUSY breaking and dark matter motivate existence of hidden sectors Dark matter motivation, CDF multimuons  recent upsurge in hidden valley models

5 5 Hidden Sectors at the LHC A scenario:  Not a Model, or even a Class of Models  A Very Large Meta-Class of Models Basic minimal structure Standard Model SU(3)xSU(2)xU(1) Communicator Hidden Sector G v with v-matter

6 6 Hidden Sectors  a collection of SM-neutral fields (1, 10, 100,…)  very weak interactions with (light) SM fields,  arbitrary self-interactions (maybe strong)  Common in string theory, extra dimensions, supersymmetry breaking  Reasonable to expect, given that there is dark matter Of course, they are often inaccessible at LHC: too weakly coupled or too heavy But if accessible, a hidden sector can drastically alter LHC pheno, so we must prepare! Very few constraints on hidden sectors  Cosmological constraints are easily evaded without altering LHC signals  LEP, Tevatron constraints are relatively weak (it’s hidden!) Thus hidden sectors are easily added to SM, MSSM, ExDim, higgs,  Without fouling anything up theoretically  Without violating any existing experimental constraints  But totally changing the LHC experimental signatures

7 7 Hidden Sectors Various non-hidden extensions of SM have been considered  More elaborate Higgs sector  New vectorlike matter  New abelian gauge groups Coupling them to new hidden-sector dynamics can give entirely new signatures  Matter with new dynamics (e.g “quirks”, “colored unparticles”)  Badly distorted Higgs (e.g. “unHiggs”)  Badly distorted Z’, etc.  Very exotic decay modes of Higgs, Z’, etc.

8 8 A Conceptual Diagram Energy Inaccessibility

9 9 A Conceptual Diagram Energy Inaccessibility Entry into Valley via Narrow “Portal” Multiparticle Production in Valley Some Particles Unable to Decay Within Valley Slow Decay Back to SM Sector via Narrow Portal

10 10 A Conceptual Diagram Energy Inaccessibility Quirk pairs are permanently bound! Quirks

11 11 A Conceptual Diagram Energy Inaccessibility Quirk pairs are permanently bound! Quirks Relax toward ground state emitting soft particles

12 12 A Conceptual Diagram Energy Inaccessibility Quirk pairs are permanently bound! Quirks Annihilate into hard SM particles Relax toward ground state emitting soft particles

13 13 A Conceptual Diagram Energy Inaccessibility Quirk pairs are permanently bound! Quirks Annihilate into Hidden Sector Relax toward ground state emitting soft particles

14 14 Hidden Valleys, Unparticles, Etc. MJS-Zurek 2006

15 15 Hidden Valleys, Unparticles, Etc. Lower mass gap  invisible (almost) to LHC

16 16 Hidden Valleys, Unparticles, Etc. Lower mass gap  invisible (almost) to LHC Conformal Dynamics well above mass gap  “unparticles” (unusual kinematic distributions in inclusive distributions) Georgi 2007 Scale Invariant

17 17 Hidden Valleys, Unparticles, Etc. Lower mass gap  invisible (almost) to LHC Conformal Dynamics well above mass gap  “unparticles” (unusual kinematic distributions in inclusive distributions) Conformal Dynamics above Mass Gap below unparticle AND hidden valley Scale Invariant Mass Gap

18 18 Hidden Valleys, Unparticles, Etc. Lower mass gap  invisible (almost) to LHC Conformal Dynamics well above mass gap  “unparticles” (unusual kinematic distributions in inclusive distributions) Conformal Dynamics above Mass Gap below unparticle AND hidden valley Scale Invariant Mass Gap Both Hidden Valley and Unparticle phenomenology may be simultaneously present. But HV phenomenology appears in exclusive measurements: 2010 Testing for scale invariance requires inclusive ones – hard!! 2015

19 19 How to address the question Questions I am often asked by experimentalists:  How should I search for hidden valleys?  How should I search for unparticles? How do I look for SUSY? Follow the logic!  SUSY predicts a superpartner for each SM particle  Avoiding proton decay motivates R-parity  R-parity implies no resonances  R-parity implies a stable LSP  Cosmological constraints imply stable LSP is neutral  R-parity with neutral LSP implies MET in each event But no such powerful logic constrains hidden sectors

20 20 How to address the question Questions I am often asked by experimentalists:  How should I search for hidden valleys?  How should I search for unparticles? Probably not the right questions:  Hidden valleys: there are numerous classes of visible signatures Long-lived particles, OR High multiplicity events, OR (more below)  Unparticles: Signatures are broad distributions, need lots of signal --- First need to determine that a signal is present! So a high-precision search for deviations from SM is needed first

21 21 Need to divide and conquer New invisible signatures  MET + X; how do we study a invisible sector? Novel visible signals found in standard places  Careful tests of SM distributions  High-precision measurements of deviations New visible signatures found in weird places  Long-lived particles  New resonances or endpoints requiring unusual event selection  High-multiplicity events  Unusual clustering of objects  Strange event shapes  Unusual tracks  Physics hiding in underlying event

22 22 Need to divide and conquer New invisible signatures  MET + X; how do we study a invisible sector? Novel visible signals found in standard places  Careful tests of SM distributions  High-precision measurements of deviations New visible signatures found in weird places  Long-lived particles  New resonances or endpoints requiring unusual event selection  High-multiplicity events  Unusual clustering of objects  Strange event shapes  Unusual tracks  Physics hiding in underlying event Very important But not so urgent Very important But not so urgent Potentially Urgent

23 23 New Invisible Signatures from Any Source How do we study and diagnose a invisible hidden sector?  First, find MET + X signal ! (2010) This is a standard search.  Second, measure it to death: (2012) Find MET+ X’, MET + X’’ Measure lots of kinematic distributions  Third, figure out what’s going on: (2015) Rule out simple ideas using transverse-mass methods (MT2 etc.?) Combine measurements to determine production mechanism Remove its kinematic dependence, then constrain the source of the MET This process will typically take a long time! Not urgent.  Rarely will a single, early analysis figure out what is behind a MET signature

24 24 Invisible Hidden Sectors t  c + invisible What’s the invisible stuff?  Three free invisible particles?  A variety of invisible bound states?  Unparticles? (scale-invariant dynamics not describable as particles) Challenge: to test for “unparticles”, observables inclusive Georgi 07 must measure all events (or correct for those you don’t) t b e t c Find the MET signal first! A Standard Search

25 25 Urgent Exception: Invisible “UnHiggs” If the Higgs mixes with and/or decays to an invisible hidden sector, problematic! Gunion et al. 97  Consider a very large number of doublet and/or singlet Higgs bosons, some with vevs  Effect: Higgs signals are all spread out into a continuum or near-continuum Quiros et al. (“singlet” unHiggs) Terning et al. (“doublet” unHiggs)  The first is obviously consistent, the second non-obviously consistent, with LEP bounds  Higgs may be completely invisible in these cases  Similar experimental issues as very wide Higgs with huge invisible width.  In this case it may have been accessible, but missed, at LEP Signatures?  Broad invisible Higgs very tough; needs study in VBF. Are there other signatures? If hidden sector is visible, it may be much better.  UnHiggs may have hidden-valley-type high-multiplicity decays; Difficulty varies: 4 b’s, tough; 4 leptons, easy; many other options.

26 26 Novel Signals in Standard Searches Classic model-independent searches for deviations from SM predictions may well turn up visible effects due to a hidden sector. Certain hidden valleys and other models can give  Diphoton resonances in di-photons+jets  Higgs  Z’ Z’  4 leptons (Z’ very light) Quirk annihilation can give  Excess and kinematic structure in W+photon events Certain hidden valley and unparticle (Feng et al.) models can give  Excess of 3 or 4 photon events, multilepton events, … Many other examples… This takes a long time – 2012? 2015? – and is not urgent Model-dependent, targeted searches can be done, in principle, but suffer from Too many models In many models, lack of theoretical methods for accurately calculating signals

27 27 Novel Signals in Quasi-Standard Searches Stau-like particles or R-hadron like particles may have hidden interactions  With MET disappearing into invisible hidden sector Possibly unparticle sector [Terning et al. 07, colored unparticles]  Or accompanied by visible effects from hidden valley [MJS + Zurek 06] Long-lived particles Multiparticle production Experimentally this is not urgent:  Find the stau-like or R-hadron like objects (2011)  Measure the MET or accompanying particles (2013)

28 28 Signals in new places: Hidden Valleys  Lots and lots and lots of new signals (I’ll show just a few) Quirks  Weird tracks  Hiding physics where you least expect it

29 29 General Predictions of HV Scenario New neutral resonances  Maybe 1, maybe 10 new resonances to find  Many possible decay modes Pairs of SM particles (quarks, leptons, gluons all possible; b quarks common) Triplets, quartets of SM particles…  Often boosted in production; jet substructure key observable Long-lived resonances  Often large missing energy  Displaced vertices common (possibly 1 or 2, possibly >10 per event) … in any part of the detector Great opportunity for LHCb if rates high Problem for ATLAS/CMS trigger if event energy is low Multiparticle production with unusual clustering  Exceptionally busy final states possible 6-20 quarks/leptons typical in certain processes up to 60 quarks/leptons/gluons in some cases  Breakdown of correspondence of measured jets to partons  Very large fluctuations in appearance of events hep-ph/0604261

30 30 Effects on Narrow-Width Particles: Possible big effect on Higgs  Long lived particles: H  XX, X decays displaced  new discovery mode not unique to HV!!! Chang Fox Weiner 05 / Carpenter Kaplan Rhee 06  High multiplicity decays: H  XXX, XXXX, etc not unique to HV!!! Chang Fox Weiner 05 Big effect on SUSY, UED, Little Higgs – any theory w/ new global charge  LSP (or LKP or LTP) of our sector can decay to the valley LSP/LKP/LTP Plus SM particles or Plus hidden particles which decay back to SM particles or Plus both  Either the hidden particles or the LSP/LKP/LTP may be long-lived;  LSP may have high-multiplicity decays;  SUSY events have significantly reduced MET Generalizes well known work from 90s [GMSB, Anomaly, Hidden Sector] hep-ph/0607160 hep-ph/0604261 hep-ph/0605193

31 31 Various possibilities to consider today Long-lived particles  Triggering, Reconstruction, Analysis? New di-lepton/di-photon resonances etc.  High boosts  High multiplicity, clustering  Complex event structure New di-tau, di-jet resonances etc.  Muons, tracks and MET  Jet substructure  High multiplicity, clustering  Soft particles from soft jets Entirely soft signals  Soft jets and leptons in jets  Soft photons

32 32 Long-lived particles

33 33 Lifetimes Long for Many Reasons Many ways to have long lifetime for v-particles  Light v-particle has little phase space  Heavy mass, weak coupling, or mixing of communicator  Loop factors in communicator mechanism  Approximate global symmetry in v-sector (e.g. vFCNCs)  Approximate global symmetry in SM sector  Etc. Multiple v-particles in each model  multiple lifetimes V-particle decays may easily be anywhere  prompt (d < 0.1 mm)  displaced (0.1 mm < d < 3 cm)  highly displaced (3 cm < 10 m)  outside detector (> 10 m)

34 34 Example #1: Higgs boson decay Higgs boson very sensitive to new sectors  True for light higgs, any CP-odd higgs Weak coupling to b quarks  New interaction can easily generate new decay mode Branching fraction can be 1, or.01, or.0001 Can cause substantial reduction in h  photons  Rare decays can be experimentally important even for heavier Higgs Well-known in wide range of models  h  invisible (1980s)  h  4 b’s, 4 tau’s (NMSSM : Dermisek and Gunion 2004)  Even h  8 b’s (Chang, Fox and Weiner 2005)

35 35 g g h hvhvhvhv mixing b b b b Displaced vertex Very difficult to trigger at ATLAS/CMS… Reconstruction challenges… LHCb opportunity!! Similar Observations: hep-ph/0607204 : Carpenter, Kaplan and Rhee Precursor (LEP focus): Chang, Fox and Weiner, limit of model mentioned in hep-ph/0511250 hep-ph/0604261 hep-ph/0605193 v-particles

36 36 Charged hadron High pT Low pT Electron Muon Photon Neutral Hadron Tracker All tracks are “truth tracks” No magnetic field Tracks with pT < 3 GeV not shown Tracker radius 3 m Calorimeter. Energy per 0.1 bin in azimuth Length of Orange Box = Radius of Tracker for total transverse energy = 1 TeV

37 37 Long-Lived Neutral Weakly-Interacting X Partial List of Experimental Challenges for H  X X, X long-lived  Trigger Muons lack pointing tracks Jets are low pT, don’t trigger Vertex may be rejected (too far out to be a B meson) Weird-looking event may fail quality control  Reconstruction Event may be badly mis-reconstructed Tracks may be missed Calorimeter effects may be misconstrued as cavern background etc. Event may not be flagged as interesting May be thrown into bin with huge number of unrelated, uninteresting events  Event Selection The events may be scattered in different trigger streams, reconstruction bins If an event was not flagged as interesting in reconstruction, how is it to be found?  Analysis What precisely to look for if the decays are outside the early layers of the tracker? What can be done if decays are in calorimeter or muon system?

38 38 Production #1: Higgs boson decay What can a new valley sector do? Higgs  X X (new [pseudo]scalars)  X  heavy flavor  H  4 b’s or tau’s Higgs  F F (new fermions)  F  jets + MET, etc. Higgs  Y Y (new vectors)  Y  jets, mu pairs, e pairs, neutrinos Other final states possible  H  YY  XXXX  8 b’s or tau’s (or mu’s)  H  FF  4 b’s, tau’s plus MET  H  XX  YYYY  8 soft quarks/leptons  … X decayComment PromptDifficult if all b’s, tau’s; easy if many muon or electron pairs DisplacedNew Discovery Channel?! Highly Displaced New Discovery Channel?! Outside Detector Invisible Higgs

39 39 Recent CDF paper and interpretation Multi-muon study: unexplained clusters of displaced muons Interpretation paper ( P. Giromini, F. Happacher, M.J. Kim, M. Kruse, K. Pitts, F. Ptohos, S. Torre )  p pbar  ???  h h  ss ss  xxxx xxxx  [8 + 8] taus x  t + t - with lifetime of 20 ps  Perfectly ok as a theory (no LEP constraints, etc.)  Not great fit to the data h, s, x masses fine tuned, x  m + m - should have been seen, …  Other variants (replace x with fermion f  t + t - n) Questions: IF this theory, or a similar hidden valley, were true,  what could be done to improve the current analysis?  how could the reconstruction software have been written to make this easier to find or exclude?  what would have been the ideal analysis technique?

40 40 Example #2: Decays to QCD-like Sector A case illustrating high multiplicity events without a corresponding Feynman diagram…

41 41 q q  Q Q : v-quark production q q Q Q Z’ v-quarks Analogous to e+e-  hadrons

42 42 q q  Q Q q Q q Q Z’ v-gluons Analogous to e+e-  hadrons

43 43 q q  Q Q q Q q Q Z’ Analogous to e+e-  hadrons No (or very low) mass gap? Invisible; Maybe Unparticle-like Larger mass gap from Higgsing, Confinement, etc.? Hidden Valley: Possibly Visible

44 44 q q  Q Q q q Q Q v-hadrons Z’ Analogous to e+e-  hadrons

45 45 q q  Q Q q q Q Q v-hadrons But some v- hadrons may decay in the detector to visible particles, such as bb pairs, qq pairs, leptons etc. Z’ Some v-hadrons may be (meta)stable and therefore invisible Analogous to e+e-  hadrons

46 46 Z’  many v-particles  many b-pairs, some taus, some MET Must be detected with very high efficiency  Online trigger to avoid discarding  Offline reconstruction to identify or at least flag Note:  Decays at many locations  Clustering and jet substructure  Unusual event shape (can vary widely!)

47 47 Effect of Magnetic Field Effect of the magnetic field on HV events (picture courtesy of ATLAS Rome/Seattle/Genoa working group)

48 48 Z’ mass = 3.2 TeV v-pi mass = 50 GeV Flavor-off-diagonal v-pions stable Prompt decays: MJS 08 Z’  v-hadrons Average: 8 b’s Max: 22 b’s

49 49 Prompt Decays: Various Lessons Low-mass dilepton (e, mu) or diphoton resonances – easy, BUT  Low-mass resonances may be produced only in high-energy events Typically produced with high boost, small angles: May violate lepton/photon isolation requirements; need to loosen these criteria  (Analysis? Reconstruction? Trigger???)  Low-mass resonances sometimes produced with multiplicity>1 Look especially in events with >2 leptons and/or photons  Rare resonances/edges/endpoints swamped by SM background unless one imposes unusual event selection criteria Look for rare di-lepton resonances in events  With large MET, or  With 6 or more jets, or  With unusually high hemisphere mass, or … An Example: Han, Si, Zurek & Strassler 2007 See also unpublished Haas, Wacker And Arkani-Hamed and Weiner 2008

50 50 New Resonances: di-leptons (e, mu) (di-photons similar) Everynone knows we should to look for resonances in leptons and photons The problem: how to find them if they appear only in rare events Without correct event selection, drowned in Drell-Yan or lost altogether Two step process:  Select events with leptons/photons (isolated?!) and some other characteristic(s)  Plot invariant masses of lepton or photon pairs, etc. An Example: Han, Si, Zurek & Strassler 2007 See also unpublished Haas, Wacker

51 51 Z’  v-hadrons Including ~ 200 GeV dilepton resonances HVMC1.0 Mrenna,Skands,MJS

52 52 Dilepton Mass Distribution Same Flavor Opposite Sign Opposite Flavor Opposite Sign v-rho v-omega If you could find enough events… in a sample with low Drell-Yan background… Event selection: use event shapes, object multiplicity, HT, possibly MET Could be much lighter – 20 GeV?

53 53 With MET? With >1 Hard Jets? Non-Isolated? Z’  v-hadrons Including ~ 10 GeV dilepton resonances HVMC1.0 Mrenna,Skands,MJS

54 54 Dilepton Mass Distribution Same Flavor Opposite Sign Opposite Flavor Opposite Sign v-rho v-omega If you could find enough events… in a sample with low Drell-Yan background… …but what should your event selection criteria be? Edge from v-rho  v-pi l + l - See also recent paper of Arkani-Hamed and Weiner (“lepton-jets”)

55 55 General Lesson Suggests – a systematic search for dilepton resonances Explore a wide variety of event classes with 2 or more leptons Important to plan in advance; perhaps discuss with theorists to look for gaps in the search strategy Both isolated and non-isolated leptons should be used Displaced leptons are also of interest Special attention to >3-lepton events (isolated or not) Also want to look for dilepton edges/endpoints Same goes for photon pairs, photon-lepton combinations, etc.

56 56 New Resonances: di-taus Essentially impossible to directly reconstruct di-tau resonances 1/36 chance to get two muons (1/9 to get two leptons) with known spectrum But typically will also see di-muon resonance!  New flavor structure in the hidden sector typically generates new FCNCs  To avoid, spin-1 resonance typically flavor blind: Br(mm)=Br(tt) mixes with photon, Z, Z’  To avoid, spin-0,2 resonance typically has Br(mm)/Br(tt) = (m m /m t ) 2 ~ 1/285 mixes with Higgs, or helicity-suppression  1/10 of di-mu decays are resonant, above bkdg from di-tau General lesson: when looking for tau’s, look for mu’s first

57 57 Taus and di-muons at 7.2 GeV This has all muon pairs, including same- and opposite-sign Also resolution is not optimized Figure produced using methods of CDF multimuon study MJS 08 Br(mm)/Br(tt) = (m m /m t ) 2 ~ 1/285 Note it is theoretically possible to eliminate the dimuon resonance; disfavored theoretically, but not excluded Compare figure with CDF multimuon study: Light vector boson or scalar boson decaying to mm with Br > 10 -3 excluded by data

58 58 More lessons: Easiest way to find di-jet resonances is if boosted  boost is common in decays of heavy particles to hidden sector (Z’, H, etc.)  cf. technical advances: Butterworth, Davison, Rubin & Salam 2008 The problem is to find them; without correct event selection, drowned in QCD So we have a three-step problem:  Select events that have a chance of containing a resonance  Study high-p T jets, look for substructure consistent with a boosted particle  Look for invariant mass peak built from the substructure of the jets Start with the substructure, then turn to event selection methods

59 59 Z’ mass = 3.2 TeV v-pi mass = 200 GeV Flavor-off-diagonal v-pions stable MJS 2008 Z’  v-hadrons Average: 3 b’s Max: 12 b’s As the mass goes down, this becomes harder

60 60 Event Selection Criteria Standard-Object-Based –  Exceptional numbers or combinations of jets/leptons/photons -- isolation?! H T / MET –  Exceptional energetics – process and cross-section dependent; typically not enough Tracks/Displaced Tracks/Vertices –  High (but possibly soft?) jet multiplicity; many b jets; particles with few ps lifetimes New Objects –  Hadronic jets with substructure  Pairs or clusters of non-isolated leptons  Narrow di-tau candidates  R-hadron candidates (loose criteria)  Jets with very low ECAL/HCAL and few tracks Overall Event Shapes – needs development  High-thrust events vs. Spherical events  Spiky events vs. Mushy events  Asymmetric events vs. Symmetric events How do we calibrate these techniques and measure backgrounds?!!!?

61 61 Event Selection Criteria Object-Based Selection High multiplicity of standard objects  Caution: at very high quark/lepton/gluon/photon multiplicity, jets merge, leptons/photons fail isolation Multiple leptons or photons?  Relax or remove isolation criteria?  Look at clustering?

62 62 Z’ mass = 3.2 TeV v-pi mass = 50 GeV Flavor-off-diagonal v-pions stable Prompt decays: MJS 08 Z’  v-hadrons Average: 8 b’s Max: 22 b’s

63 63 Quarks vs Jets Counting objects can be inefficient

64 64 Event Selection Criteria Tracks/Vertices Signal with many soft particles:  count tracks rather than jets/leptons Signal with many v-particles  b quark pairs  Many B-mesons – often many more B-mesons than jets  Don’t just tag the jets – count tracks, vertices, displaced tracks study clustering of tracks and vertices Signal with v-particles  jets with lifetime 1 ps  One vertex for each jet pair  Look for jets that share a displaced vertex with many tracks

65 65 5 cm Pixels Dotted blue lines are B mesons Track pT > 2.5 GeV Multiple vertices may cluster in a single jet Event Simulated Using Hidden Valley Monte Carlo 0.4 (written by M. Strassler using elements of Pythia) Simplified event display developed by Rome/Seattle ATLAS working group All tracks are Monte-Carlo-truth tracks; no detector simulation

66 66 1 cm Dotted blue lines are B mesons Jet VTX Track pT > 2.5 GeV Event Simulated Using Hidden Valley Monte Carlo 0.4 (written by M. Strassler using elements of Pythia) Simplified event display developed by Rome/Seattle ATLAS working group All tracks are Monte-Carlo-truth tracks; no detector simulation

67 67 Dotted blue lines are B mesons Dotted green lines are v-pions 1 cm Jet VTX The third vertex does not “belong” to either jet Track pT > 2.5 GeV

68 68 Event Selection Criteria H T / MET For a process with high parton-parton invt. mass Few if any v-particles decay invisibly  large HT, low MET, high multiplicity  Moderate QCD, tt backgrounds Large fraction of v-particles decay invisibly  medium HT, medium MET, medium multiplicity  Large Z + jets etc. backgrounds

69 69 Z’ mass = 3.2 TeV v-pi mass = 50 GeV Flavor-off-diagonal v-pions unstable MJS 2008 Z’  v-hadrons Average: 20 b’s Max: 42 b’s

70 70 Z’ mass = 3.2 TeV v-pi mass = 50 GeV Flavor-off-diagonal v-pions stable Prompt decays: MJS 08 Z’  v-hadrons Average: 8 b’s Max: 22 b’s

71 71 MET vs HT Models with all v-particles decaying visibly Models with ~2/3 of v-particles stable and invisible

72 72 Event Selection Criteria Overall Event Shapes … relatively unexplored territory Events with few invisible particles:  Tend to be oblong to spherical, not like dijets  Tend to be different from tri-jets (acoplanarity in some frame)  May be “spiky” or “mushy” Events with many invisible particles  Tend to be asymmetric (but so is Z + jets)  Highly variable!!!! Hard to get large sample with any one criterion E.g. multiplicity of visible particles varies widely  May be “spiky” or “mushy” but not always so distinctive

73 73 Z’ mass = 3.2 TeV v-pi mass = 50 GeV Flavor-off-diagonal v-pions unstable MJS 2008 Z’  v-hadrons Average: 20 b’s Max: 42 b’s

74 74 Z’ mass = 3.2 TeV v-pi mass = 50 GeV Flavor-off-diagonal v-pions stable Prompt decays: MJS 08 Z’  v-hadrons Average: 8 b’s Max: 22 b’s

75 75 UV Weak-Coupling (small anom dims) ~ 10 v-hadrons Some hard, some soft ~ of order 20 quarks/leptons of widely varying pT Z’

76 76 UV Strong-Coupling Fixed Point (large anom dims) ~ 30 v-hadrons Softer v-hadrons ~ 50-60 soft SM quarks/leptons Event from educated guesswork! Crude and uncontrolled simulation Fix  in HV Monte Carlo 0.5 at large value This increases collinear splitting Check that nothing awful happens Check answer is physically consistent with my expectation Z’ This hidden valley is also an “unparticle theory with a mass gap”

77 77 Quirks Two heavy SM-charged particles bound by a hidden flux tube  If charged, color-neutral quirk is like stau  If colored, forms new hadron (like R-hadron) Dynamics depends on tension of flux tube (i.e. hidden confinement scale) Very low tension – two charged particles following weird tracks  Interesting trigger and tracking issues -- timing Higher tension –  Relaxes toward (not always to) ground state in microscopic time  Annihilates to hard SM or hidden-sector particles (visible or invisible)

78 78 Quirk Annihilation Products are Hard Quirks  W gamma 300 GeV 500 GeV 800 GeV

79 79 Quirk Relaxation Products are Soft Quirks  W gamma + relaxation effects – 400 soft photons + 400 soft charged pions? 300 GeV 500 GeV 800 GeV Correlation of hard W+gamma with oddly shaped active UE allows diagnosis! Kang Luty 08 see also Chacko et al 07

80 80 Summary of the Chaos Theorists have uncovered a plethora of fascinating signatures that new physics might display – but do not yet fully understand how to find them Some of these can be studied after discovery of a deviation from the SM is made using standard methods [Badly distorted Higgs?!] But many (esp. hidden valleys and quirks) require new types of searches  Standard searches with non-standard event selection  New types of criteria for event selection  New methods to deal with high multiplicity, poor isolation, soft physics  New jet methods to deal with substructure, clustering  New shape variables needed  Specialized searches for long lifetimes, weird tracks Many of these require specialized trigger, reconstruction, and/or analysis Some Event Generators Exist!


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