Transcript LHC(b) Physics and Prospects

LHC
The Energy Frontier
LHCb
ATLAS
CMS
Chris
Parkes,
Chris
Parkes GridPP 8, April 2012
ALICE
1
Two Routes to New Physics
• Direct Production
• Indirect Effects
E=mc2
b
New particles
• Simpler to
interpret
• Probes masses
<E
Chris Parkes
• Model dependent
interpretations
• Probes very high
mass scales –
virtual new particles
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Contents: Selected new results
• LHC Status
– 2011 data and 2012 expectation
• Heavy Ions (mainly ALICE)
– Suppression/enhancement of particle rates
• Direct Production (mainly ATLAS/CMS)
– The ‘H’ word
– Electroweak / Top physics
– SUSY
• Indirect effects (mainly LHCb)
– Rare Decays
– CP Violation - charm
Chris Parkes
Sources:
Moriond
E’weak,
LHCC
3
LHC: The New Improved Energy
Frontier
Chris
Parkes,
Chris
Parkes GridPP 8, April 2012
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Mike Lamont, LHCC
2011 – recap
75 ns
50 ns
Scrubbing
Increase number
of bunches
Initial
commissioning
Squeeze
further
25 ns
test
Increase
bunch
intensity
Reduce
beam size
from
injectors
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•
•
LHC Performance
LHC shows excellent performance
First two years of physics
• Recorded 40 pb-1 in 2010 at 7 TeV + Pb-Pb
• Recorded 5 /1 fb-1 in 2011 at 7TeV + Pb-Pb
• 2012 – now restarted at 8 TeV
Power of Grid:
All collected data reconstructed and many results on full samples6
2012 LHC schedule Q1/Q2
First Collisions
Aims for year:
ATLAS/CMS – need max luminosity
many interactions per bunch crossing
>15 fb-1 (3x 2011)
LHCb – need seconds !
small number interactions per bunch
> 1.5fb-1
ALICE – heavy ions
First proton – lead collisions
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Mike Lamont, LHCC
2012 LHC schedule Q3/Q4
Protonlead
Special
runs
Followed by long shutdown to move to ~14 TeV
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Heavy Metal Frontier
Lead Ions
Chris
Parkes,
Chris
Parkes GridPP 8, April 2012
9
Hadrons suppressed but photons
shine !
Hadrons up to pT 100 GeV/c are suppressed
Photons up to ET 80 GeV are not
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LHC: The Energy Frontier
Direct Production
Chris
Parkes,
Chris
Parkes GridPP 8, April 2012
11
Chris Parkes
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Higgs 101
1) The last undiscovered particle in the Standard Model
Standard Model Particles
– Higgs Mechanism gives masses to the W & Z
Chris Parkes
Higgs boson,
spin=0
Electric charge 0
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Higgs 101
1) The last undiscovered particle in the Standard Model
– Higgs Mechanism gives masses to the W & Z
2) The mass of the Higgs boson is not predicted
– The rate of production (cross-section) is
predicted if you know the mass
Higgs boson
Mass = ?
Chris Parkes
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Higgs 101
BR
3) The Higgs boson has lots of possible decay modes
– It prefers to decay to the heaviest thing available
– Couples to mass
– But easier to find if low background rates
– Best channel changes with Higgs mass
Chris Parkes
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Standard Model Higgs ?
Combination of many decay channels with FULL 2011 data sample
95% CL Limit on s/sSM
•
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ATLAS Preliminary
2011 Data
ò
Obs.
Exp.
±1 s
±2 s
-1
Ldt = 4.6-4.9 fb
s = 7 TeV
1
10-1
CLs Limits
100
200
300
400
500
600
mH [GeV]
1) Black solid line below 1: excluded.
Observed number of events less than would
have if the Higgs had that mass
9
16
Standard Model Higgs ?
95% CL Limit on s/sSM
• Zoom in on interesting region
ATLAS Preliminary
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Obs.
Exp.
±1 s
±2 s
2011 Data
ò
-1
Ldt = 4.6-4.9 fb
s = 7 TeV
1
-1
10
CLs Limits
110 115 120 125 130 135 140 145 150
mH [GeV]
2) Black dashed line : expected if no Higgs
Black solid > black dashed = hint of a Higgs signal
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Standard Model Higgs ?
• Black line –
~probability of Higgs
at that mass
• Sensitivity comes
from ϒϒ channel
• ATLAS/CMS
compatible
• New Tevatron result
– also compatible
CMS Expected exclusion 114.5 - 543 GeV
CMS Observed exclusion 127.5 - 600 GeV
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Narrowing in on the Higgs
• Black line – From
Indirect Effects:
top mass and
(new) Tevatron W
mass
• Yellow blocks –
excluded by direct
searches
Indirect Effects: Prediction is from Electroweak resultsW mass and top mass
Chris Parkes
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Electroweak
stotal [pb]
Cross-sections of Electroweak processes
105
ATLAS Preliminary
-1
35 pb
ò
35 pb-1
104
-1
-1
L dt = 0.035 - 4.7 fb
s = 7 TeV
Theory
Data 2010
Data 2011
103
102
1.0 fb-1
0.7 fb-1
4.7 fb-1
1.0 fb-1
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4.7 fb-1
W
LHC status
Z
tt
t
WW
WZ
ZZ
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W and Z Production
• W/Z cross-section ratio
– sensitive test of SM at LHC
• W Charge Asymmetry
W  W

W  W



– changes sign in LHCb region: constraints on the low x
quark content of the protons at high q2.

ATLAS/CMS
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Top Quark
Chris Parkes
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Top Quark
Top quark spin
correlations measured for 1st time
Chris Parkes
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Top Quark
Top quark mass
approaching Tevatron
precision
Chris Parkes
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Supersymmetry (SUSY) 101
Propose new symmetry of nature: Supersymmetry
Spin ½ Fermions (quarks, leptons)  spin 0 boson superpartner
Spin 1 Bosons  spin ½ fermion superpartner
SUSY not an exact symmetry
Mass of SUSY particles ≠Mass of normal particles
Since none discovered yet
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SUSY Motivation
2. SUSY cancels
divergences in SM
1/Strength
1. SUSY allows unification of the forces
Log Energy GeV
3. Lightest SUSY particle (LSP)
is candidate for dark matter
Most models LSP is stable
neutralino
4. SUSY provides a theoretical route to include gravity in
“standard model”, and needed in string / M-theory
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SUSY: theoretically beautiful and convenient – but is it true ?
SUSY + Exotics Searches Summary
ATLAS – many analyses with FULL 2011 Luminosity
Optimal use of delivered data: Enlarge range of “experimental
topologies”
look at as many “experimental topologies” as possible
Then make happy our friend theorists:
translate results in constraints to large variety of models
F. Cerutti - LNF-INFN
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SUSY + Exotics Searches Summary
Good Fraction of analyses updated with FULL
2011 Luminosity
SUSY is alive but she
has a
headache
Optimal use of delivered data: Enlarge range of “experimental
topologies”
look at as many “experimental topologies” as possible
Then make happy our friend theorists:
translate results in constraints to large variety of models
F. Cerutti - LNF-INFN
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Muon System
RICH Detectors
Vertex
Locator
Beyond The Energy Frontier
Indirect Effects
Interaction
Point
Calorimeters
Chris
Parkes,
Chris
Parkes GridPP 8, April 2012
Tracking System
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Rare Decays: Bsμ+μ-
SM prediction 3.2 x 10–9
• Very rare decay – enhanced rate by new physics
–
LHCb rate < 4.5 x 10–9 (95%CL), CMS rate < 7.7 x 10–9 (95%CL), ATLAS < 22 x 10–9 (95%CL)
• New physics SUSY models with
large tan β ~ ruled out
green – allowed regions
black/red – exclusion limits from CMS
yellow - exclusion region from LHCb Bs→μμ result
N. Mahmoudi
Chris Parkes
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Most rare decay ever seen !
• B+ → π+μ+ μ–
– First observation
• 25±6 events
• 5.2 σ significance
Beyond the Energy Frontier
0
B
→
*0
+
–
K μμ
- Constraining new
physics up to 10TeV
Chris Parkes
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Matter anti-matter (CP violation) 101
Charge Inversion
Particle-antiparticle
mirror
C
P
Parity
Inversion
Spatial
mirror
CP
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CP Violation Discoveries
• Strange Quark System (Kaons)
– Discovery of CP Violation
• Beauty Quark systems (B)
– CP violation theory in CKM matrix
– Also Bs, see next slide
• Charm System (D)
– Is there CP Violation in Charm quarks ?
– Predicted to be very small in SM
– Good way of searching for New Physics ?
Chris Parkes
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Bs Matter Antimatter Asymmetry
ArXiv:1202.6251v1, Feb 2012
B
6σ
Asymmetry
Bs
3.3σ
Asymmetry
Chris Parkes
B
Bs
FIRST CP
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CP Violation in Bs → J/ψϕ
1 fb-1, LHCb-CONF-2012-002
• Powerful analysis to look for New Physics
• Had been hints from TeVatron – but more
precise LHC results give SM value
Chris Parkes
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LHCb LHCc
c
• LHCb was designed for b-quark studies
• But also ideal for studies of slightly shorter
lived c quark, and 20 times more events
• CP Violation in charm sector (was) predicted
to be very small in Standard Model < 0.1 %
• Bigger than this New Physics !
e.g.
Chris Parkes
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CP Violation: Problem 1 – Initial Condition
• Technical Scale Drawing of LHC Collision
Proton
(Matter)
Proton
(Matter)
• Start with matter and no antimatter
• Ending with more matter than antimatter is not a surprise
Take difference in CP Violation between two decays
Chris Parkes
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CP Violation: Problem 2 – Detector
• Particles bend in magnetic Field
+ve charge
-ve charge
• So if matter goes to a +ve particle and antimatter to –ve
• Go to different parts of detector – can fake CP violation
1)Take difference in CP Violation between two decays
2)Reverse Magnetic Field Periodically
3)Choose a symmetric decay
Chris Parkes
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Direct CP Violation in Charm


A CP (K K ) 


A CP (   ) 








( D  K K )  ( D  K K )
( D  K K )  ( D  K K )








( D    )  ( D    )
( D    )  ( D    )
A RAW ( f )  A CP ( f )  A Detector ( f )  A Production
What we
measure
Chris Parkes
What we
want
What we
What we
don’t want (1) don’t want (2)
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Direct CP Violation in Charm


A CP (K K ) 


A CP (   ) 








( D  K K )  ( D  K K )
( D  K K )  ( D  K K )








( D    )  ( D    )
( D    )  ( D    )
A RAW ( f )  A CP ( f )  A Detector ( f )  A Production
What we
measure
What we
want
What we
What we
don’t want (1) don’t want (2)
Symmetric Final State
Chris Parkes
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Direct CP Violation in Charm


A CP (K K ) 


A CP (   ) 








( D  K K )  ( D  K K )
( D  K K )  ( D  K K )








( D    )  ( D    )
( D    )  ( D    )
A RAW ( f )  A CP ( f )  A Detector ( f )  A Production
What we
measure
What we
want
What we
What we
don’t want (1) don’t want (2)
Symmetric Final State
Magnetic Field
Chris Parkes
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Direct CP Violation in Charm




A CP  A CP (K K )  A CP (   )
A RAW ( f )  A CP ( f )  A Detector ( f )  A Production
What we
measure
What we
want
What we
What we
don’t want (1) don’t want (2)
Symmetric Final State
Magnetic Field
Take Difference of final states
Chris Parkes
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 A CP
Direct CP Violation in Charm
Phys. Rev. Lett. 108, 111602 (2012), 12th March 2012
 A CP   0 .82  0 .21 ( stat .)  0 .11 ( syst .) %
• High Statistics
– 1.4M K+K-, 0.4M π+π-
Chris Parkes
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 A CP
Direct CP Violation in Charm
 A CP   0 .82  0 .21 ( stat .)  0 .11 ( syst .) %
New Prelim Result, 28th February
 A CP   0 .62  0 .21 ( stat .)  0 .10 ( syst .) %
• Confirmation of Effect
• World Average 3.7 σ
Chris Parkes
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 A CP
Direct CP Violation in Charm
Interpretation: M. Gersabeck, S. Borghi, CP
http://arxiv.org/abs/1111.6515
Average: Marco Gersabeck
• First evidence of CP violation in charm sector
Chris Parkes
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New Physics ?
• CP Violation in charm sector (was) predicted
to be very small in Standard Model < 0.1 %
• We measure 0.82±0.24% (on difference)
• New Physics ?
• Well maybe not…
Chris Parkes
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• Pb – Pb collisions
2011 Summary
– Particle suppression / enhancement in new state of matter
• Higgs:
– Tantalising hints of SM Higgs around 125 GeV
• We will know this year
• SUSY:
– No signs of her yet in direct production or rare
decays
• Rare Decays:
– Most rare decay ever seen
• CP Violation:
– First evidence for CP violation in charm sector
• Compatible with SM ?
Chris Parkes
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• Pb – Pb collisions
2011 Summary
– Particle suppression / enhancement in new state of matter
• Higgs:
2012
– Tantalising hints of SM Higgs around 125 GeV
• We will know this year
• SUSY:
New World record energy
– No signs of her yet in direct production or rare
decays
• Rare Decays:
Expect
more
– Most rare
decay lots
ever seen
data for
Grid to reconstruct
• CP Violation:
– First evidence
for CPPhysics
violation in?charm sector
New
• Compatible with SM ?
Chris Parkes
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