# Presentation: 388227

## Physics of the Linear ColliderF. Richard LAL/Orsay

## Outline

- Which machine ?
- (Which detector ?)
- For which physics ?   Possible scenarios
-      Origin of mass EWSB          Main emphasis
-    Hierarchy of masses            SUSY
-      Input to Cosmology
-     Major ongoing effort in Americas, Asia, Europe
-      Apologies: incomplete picture in 30’ +  personal biases

## Machine 

- The baseline is an e+e- LC operating from MZ to 500 GeV with polarized e- (80 %) and collecting 500 fb-1 in the 1st 4 years of running
- Upgradeable to ~ 1 TeV 500fb-1 /year
-    Options :
- e+ polarization (60%) needed at GigaZ and with transverse polarization
- e-e- ~ easy                ~*L*e+e-/3*  *s~0.8s
-  e more involved    High pol.  xssing angle

## Which Scenario for EWSB?

-     LEP/SLD/Tevatron legacy:
- SM/MSSM compatible with PM
- MSUSY 1-10 TeV ~GUT with some
-      small but interesting discrepancy
-   -> A light Higgs is expected <250 GeV
-     However:
- AbFB (NuTeV) not understood Th/exp
- Could be a fake  (Peskin-Wells) if there are extra contributions as in alternate schemes  to SM/MSSM
-      3 EWSB scenarios for LC:
-       MSSM                PM on Higgs couplings with ~105 HZ
-       mH > 200 GeV     Direct/Indirect signals of new physics
-       S.I. no Higgs       PM at TeV primarily with WW final states
-    -> Can LC can provide sufficient observables, with proper accuracy, to cope with these 3 scenarios (including GigaZ/W)

- GigaZ

## Scénario 1Is this the MSSM Higgs ?

- D.J. Miller et al.

- NMSSM/SM

- Quantum numbers: spin with scan
- CP  from ZH angles
-    ff  and gZZ/WWH at %
-     20 % at % with coll
-     gttH  7-15% mH 120-200 GeV
-     HHH~20%(10%) s 500(800)GeV
- Within MSSM: mA from bb/WW
- Beyond MSSM:NMSSM, CP violation
-  -> Measurable changes on gZZH , in some
-     cases serious reduction of HZ
-     Robustness of LC:
-     can stand   ~SM/100

- NMSSM/SM

- E. Gross

- D.J. Miller et al.

## Scénario 1Beyond  MSSM (suite) 

- Detection does not depend on final state BR
-      Example Invisible decays:
-      Long list of channels:
-      - h-> with non-universal gaugino masses
- -G within GMSB
-      - Gravitons GG, Graviscalar mixing
-      - Majorons JJ, ADD LRKK....
-       -> High sensitivity 5 BRinv=2%
- Mixing with an other scalar field
-     Radion   gg at 5%

- Rad/SM

- f,W

- g

- J. Hewett et al

- ~

- 

- F. Boudjema et al

## Quantum level consistency

-  GigaZ sin2W~10-5 with Pe+
-  WWth MW~6MeV E from Z at 510-5
-  Improved experimental inputs
-  Improved theory (Loopverein)
- MHIndirect~5% (~50 % at LEP/SLD)
- (WWth gives  MH ~10%)
- Recall that LEP/SLD did much better than anticipated

- sin2W x 106

- S. Jadach

- *L/L**th*

- 10-3

- MHDirect=MHIndirect ?

- ALR

- s

- (MZ)

- mt

## Scénario 2mH > 200 GeV

-    mH inconsistent with SM/MSSM
-     -> find the ‘guilty part’
- With direct evidence at LHC : e.g. Z’
-    -> Decipher the message, Z-Z’ mixing
-       at GigaZ, interference at high s
- Many scenarios, well separated  if
-      Z’ mass given by LHC
- In UED no Z’ ff coupling, isospin
-      violation seen with  at GigaZ
- If no evidence at LHC
-     -> Use LC to estimate the new scale

## Little Higgs with mH>200 GeV

-   ->  From LEP/SLD Most Z’ scénarios do not favor mH>200 GeV
-        What about Little Higgs ?
-      A viable alternative (hierarchy) to SUSY:
-      H ~ PG boson of a broken symmetry (several groups possible), perturbative theory up to 10-100 TeV
-  Cancellation of  quadratic divergences on mH2
-      -> New objects:   B’ W’ t’ H’...
-  B’ can contribute to  and can  ‘hide’ a heavy Higgs
-  mH>200 GeV possible given  sin2eff + MW from LEP/SLD
-       with mB’ > 2 TeV  and adjusting g’B/g’SM < 1
-  If LHC finds e.g. B’ -> LC to identify the LH scheme
-  If not, LC can predict mB’ and indicate upgrade *L*/s needed    at LHC  (or at future colliders )
-        -> Strong LHC/LC synergy

## Scénario 3No Higgs

- WLWL will strongly interact resulting in:
- Production of a resonance -type in e+eW+W-
- M < EWSB=4v=3 TeV
- Without a resonance LET still observable

-  if J=0,2  I=0,2 resonances

|  |   s   GeV |    L
 fb-1 |  M
1.6TeV | LET |
| --- | --- | --- | --- | --- |
| LC | 0.5 | 300 | 16 | 3 |
| LC | 0.8 | 500 | 38 | 6 |
| LC | 1.5 | 200 | 204 | 5 |
| LHC | 14 | 100 |  6 | 5 |

- 5 TGC conserving P, SU(2)Cust
- - 3 with WW+ GigaZ
- - 2 with WW
- All LC limits reach > EWSB

- Resonance e+eW+W-    J=1 I=1

- TGC e+eW+W-    and W+W-

- 3

- 2

## The SUSY scenario

- SUSY is the leading theory:
-      - compatible with PM (light H)
-      - mass hierarchies up to MPlanck
-      - compatible with GUT
-      - link to cosmology (e.g. DM)
- No unique SSB mechanism
- Essential goals of LC after SUSY
-     discovery by LHC:
-     - to understand SSB
-     - to determine mass and couplings
-       of the LSP for cosmology
- Using mSUGRA, for pedagogy, 4
-      regions consistent with  DM

- Focus

- Higgs Annihilation

- Co-annihilation

- Blob

- m0 GeV

- M1/2 GeV

## Caveat: Flavor constraints 

- Flavor : FCNC CP K  EDM p
-     -> Heavy sfermions (1st 2 generations)
-    -> For CP, hidden symmetry (LR) avoiding
-        phases or cancellation (?) of phases
- 3 possible scenarios:
-    - All scalars very heavy h and possibly  ’  and g accessible  at LHC/LC
-       DM ->  Wino(M2<M1)/Higssino (low μ)  ’  ~ mass degen.
-    -   t b scalars could also be observed
-       DM -> co-annihilation  Bino and  ~ mass degen. < 500 GeV
-    - Phases ~0 most sparticles could be accessible (‘blob’) at LC/LHC

- ~

- ~

- ~

- ~

- ~

- B.E. Sauer

## DM at LC

-  LC will accurately measure m and couplings,
-      i.e. Higgsino/Wino/Bino content (polar.)
-       -> Essential input to cosmology
-       -> Input for non-accelerator searches
-  In the ‘blob’ (B) mSugra scenario, LC
-      accuracy on m ~0.1 GeV, m ~0.6 GeV
-       -> Prediction of DMh2 with an accuracy
-       ~ CMB anisotropies
-       -> A mismatch would reveal extra sources of
-       DM (Axions, heavy objects)
-       Also access to meL, meR m up to ~TeV
- Less precise, but still possible (cf. LEP2)
-     in a mass degenerate scénario

| ‘WMAP’ |   7 % |
| --- | --- |
| LHC |  ~15 % |
| ‘Planck’ |   ~2 % |
| LC |   ~3 % |

- ~

- ~

- ~

- ~

- MicrOMEGAs Pt B

- J. Ellis et al

## LC and SSB 

- Model independence (large set of observables LC+LHC) High accuracy SUSY needed to to access to the underlying SSB mechanism
- Lesson from LEP/SLD on GUT
- Subtle differences (loops)
-      expected on Mi at unification
- LHC M3 error (gluino), due
-      to correlations, at ~10%
-      -> with m from LC M3
-       improved by a factor ~10
- ->   Reconstruct fundamental param
-       of an effective string theory

- -1/Mi GeV-1

- G. Blair et al

## Summary: Why do we need a LC ?

- To provide the full picture on an SM/MSSM Higgs
- To provide an answer on EWSB with difficult or unexpected scénarios : heavy Higgs, reduced Higgs x-section
- To access to the SSB mechanism with LC+LHC measurements
- To predict precisely, within SUSY,  DMh2
- To interpret unambiguously an unexpected discovery at LHC, e.g. a Z’ or a KK ?
- To estimate mass scales beyond LC/LHC reach (~LEP/SLD):
-     - Deviations on PM on Higgs couplings translated into, e.g.,  mA mH or Z’ mass
-     - Test of the theory at the quantum level which can reveal new mass scales (e.g. LEP/SLD and the Higgs mass)
-  ->  New frontier: improved LHC or future colliders CLIC VLHC

## Apologies

- Physics with CLIC
- SUSY and the neutrino sector
- Xtra dimensions: various schemes alternate or combined with SUSY
- Non-commutative effects
- Transverse polarization for Gravity induced effects
- SUSY and CP violation
- e-e-,  and e physics
- ...

## Detector

-     In many instances LC analyses will be systematics limited -> Aim at a ~perfect detector
-    3 outstanding improvements/LEP-SLD can be
-    fulfilled with LC detectors:
- Improved vertexing : c (=70% >80% pure),tau tagging
- E/E~1/2 LEP  6/8 jets reconstruction
-     WW/ZZ separation (+  )
- p/p2~1/10 LEP down to 100 mrad
-     Also:
- Hermeticity on energetic /e down to 5 mrad outstanding
-  *L,*  Polarization,  s very precise (Z physics)
-     -> Machine Detector interface activity

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