The ILC Project Physics Studies and Detector R

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The International Linear Collider
Physics Opportunities and Experimental
Techniques for the Next Large Scale Facility in
Accelerator Particle Physics
Marco Battaglia UC Berkeley and LBNL
TASI, Boulder, June 2006
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International ee- Linear Collider
ILC highest priority for future major facility in
HEP needed to extend and complement LHC
discoveries with accuracy which is crucial to
understand nature of New Physics, test
fundamental properties at high energy scale and
establish their relation to Cosmology
Technology decision promotes ILC towards next
stage in accelerator design definition, RD and
cost optimization
Matching program of Physics studies and Detector
RD needed develop new accurate and cost
effective detector techniques from proof of
concepts to a state of engineering readiness to
be adopted in the ILC experiments.
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Synergy of Hadron and Lepton Colliders
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Synergy of Hadron and Lepton Colliders
Mass scale sensitivity vs. centre of mass energy
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ILC Energy
Physics to define next thresholds beyond 100 GeV
Top Quark pair production threshold
Strong prejudice (supported by data) on Higgs and
New Physics thresholds between EW scale and 1
TeV
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ILC Energy in Perspective
Bevatron (6.2 GeV), LBNL
Cosmotron (3.3 GeV), BNL
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Centre-of-Mass Energy vs. Year
as of 1992
as of 2000
?
we have fallen off the scaling predicted by
Stanley Livingstons curve.
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Why Linear ?
Particles undergoing centripetal acceleration
av2/R radiate at rate
Synchrotron Radiation
if R constant, energy loss is above rate x time
spent in bending2pR/v
?
for e- (E in GeV, R in km)
R
for p (E in TeV, R in km)
R
Since energy transferred to beam per turn is
constant G x 2pR x F at each R there is a
maximum energy Emax beyond which energy loss
exceeds energy transferred, real limit set by
dumped power
Example LEP ring (R4.3 km) Ee250 GeV g W
80 GeV/turn
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ILC Energy
Technology to define reachable energy
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Accelerator RD reached maturity to assess
technical feasibility and informed choice of
most advantageous technology. ILC potential in
future of scientific research praised by OECD.
DOE Office of Science ranked ILC as top mid-term
project.
Major step towards construction of new HEP
facility in August 2004
Cold SC cavity technology chosen Global Design
Effort to produce costed Technical Proposal by
end 2006 CLIC technology being demonstrated by
RD CTF3 facility at CERN.
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ILC Baseline Design
9-cell 1.3GHz TESLA Niobium Cavity 35 MV/m
baseline gradient
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ILC Baseline Design
Optimisation for 500 GeV ILC Cost vs. Gradient
Cavity Gradient
Cavity Cost vs. Gradient
51 km
32 km
44 km
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SC Cavity Gradient
TESLA Cavities 2005
LEP-2 Cavities 1999-2000
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ILC Luminosity
Since cross section for s-channel processes
scales as 1/s, luminosity must scale
to preserve data statistics
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ILC Luminosity
N L x s
Luminosity functional dependence on collider
parameters
Compared to circular colliders (LEP) frep m and
must be compensated by increasing the nb. of
bunches (Nb) and reducing the transverse beam
sizes (sx, sy)
Small beam size induces beam-beam interactions
self focusing and increase of beamstrahlung
resulting in energy spread and degraded luminosity
spectrum
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ILC Luminosity Optimization
High Beam Power
Large Beamstrahlung
High Efficiency
Small vertical emittance and short bunch length
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ILC GDE Plan and Schedule
2005 2006 2007 2008
2009 2010
CLIC feasibility
Global Design Effort
Project
LHC Physics
Baseline configuration
Reference Design
Technical Design
ILC RD Program
Bids to Host Site Selection
International Mgmt
from B. Barish
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ILC Physics Objectives

• Three Main Physics Themes
• Solving the Mysteries of Matter at the
• TeraScale ( Higgs/SUSY/BSM)
• Determining what Dark Matter particles
• can be produced in the laboratories and
• discovering their identities (SUSY/ED)
• Connecting the Laws of the Large to
• the Laws of the Small (EW/SUSY/ED)

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The Higgs Boson Profile at the ILC
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Higgs Boson Production at ILC
s(ee- gH) (fb)
MH (GeV)
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Model Independent Higgs Reconstruction
Associate H0Z0 production, with Z0 gll, allows to
extract Higgs signal from recoil mass
distribution, independent on H decay
Analysis flavour blind and sensitive to
non-standard decay modes, such as Hginvisible
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Model Independent Higgs Reconstruction
H
Z
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The Recoil Mass Technique
ee- g HZ
Ecm EZ EH
0 pZ pH
MH2 EH2 pH2 (Ecm-EZ)2 pZ2
Ecm2 EZ2 EcmEZ pZ
Ecm2 2EcmEZ MZ2
Resolution on MH depends on knowledge of
colliding beam energy and on lepton momentum
resolution.
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Determining the Higgs Couplings
After discovery of a new boson at LHC, essential
to verify that this new particle does indeed its
job of providing gauge bosons and fermions with
their masses
Yukawa couplings vs. fermion mass
ILC can perform fundamental test of scaling of
Yukawa couplings with masses for Gauge bosons,
quarks and leptons with accuracy matching
theoretical predictions
Recent improvements in mb and mc determinations
at B factories make ILC measurements even more
compelling.
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Determining the Higgs Couplings
Higgs Decay Branching Fractions vs. Higgs Mass
Extract Higgs couplings from decay branching
fractions into fermions and gauge bosons and
from production cross sections (controlled
by gHZZ, and gHWW)
Excluded by LEP-2
Strong dependence on (unknown) Higgs Boson mass.
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Generation of Mass the Gauge Sector
Determine HZZ coupling from Higgstrahlung cross
section and HWW coupling from double-WW fusion
and HgWW branching ratio
gggH also possible at gg collider considered as
ILC option
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The Jet Flavour Tagging Technique
Tag H hadronic decay products to separate b, c
and g yields
Jet flavour identification relies on distinctive
topology and kinematics of heavy flavour decays

H gbb
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The Jet Flavour Tagging Technique
Short lived particle with proper time t has
a decay distance l bgct

• B from H decay at 0.5 TeV
• mB 5.2 GeV, ct 500 mm
• EB 0.7 x Ejet
• 0.7 x 500/4 100 GeV
• 70
• ltlgt 3.5 mm

• D from H decay at 0.5 TeV
• mD 1.9 GeV,
• ct (123311)/2 mm
• g 60
• ltlgt 1.3 mm

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Generation of Mass the Quark Sector
Extract individual branching fractions from
3-parameter simultaneous fit
gg
cc
bb
Coupling Accuracy for MH120 GeV
b-tag
c-tag
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Generation of Mass the Lepton Sector
Higgs decays into t pairs identified by topology,
multiplicity
Hgmm as rare decay allows test of Yukawa
coupling scaling with mass in leptonic sector
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Higgs Quantum Numbers
JPC numbers can be determined in
model-independent way
Observation of Hggg or gggH sets
and
Threshold cross section rise
and angular
dependence of the
Z boson production from longitudinal
polarization at high energies allows to
determine and to
distinguish SM H0 boson from a CP-odd A0 boson
and the ZZ background as well as from a
CP-violating mixture
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Determining the Higgs Potential
Fundamental test of Higgs potential shape
through independent Determination of gHHH in
double Higgs production
Opportunity unique to the ILC, LHC cannot access
double H Production and SLHC may have only
marginal accuracy
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Determining the Higgs Potential
Experimental challenge not only cross sections
are tiny (lt 1 fb), but need to discard HH
production not sensitive to HHH vertex.
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Double Higgstrahlung at 0.5 TeV
Double WW Fusion at 1 TeV
HH Mass
Decay Angle
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Higgs Physics and Detector Response
dpt/pt2 4 x 10-5
dpt/pt2 2 x 10-5
Reconstructing the Higgs profile sets challenging
requirements on vertexing, tracking and
calorimetry
ee "HZ " X mm
dpt/pt2 8 x 10-5
dpt/pt2 6 x 10-5
MH
BR(H"WW)
ee "HHZ
dE/E
dE/E
dE/E
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The Higgs Profile and Physics beyond
In models with extended Higgs sector, such as
SUSY, Higgs couplings get shifted w.r.t. SM
predictions
Precise BRs measurements determine the scale of
extended sector
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The Higgs Profile and Physics beyond
In models with new particles mixing with the
Higgs boson, branching fractions are
modified, generally through the introduction of
an additional (invisible) decay width
Models of extra dimensions stabilised by the
Radion are characterised by potentially large
changes to Higgs decay Branching fractions