12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
(The Uncertainties Of)
Tony Doyle
ORHunting the (non-SUPAsymmetric)
Higgs
Higgs Discovery at the LHC
ORThe Iceman Cometh
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Outline
• Ingredients1. Motivation2. Constraints3. Dependencies
A. ColliderB. DetectorC. Grid
4. Analysis
Discovery? When?
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Introduction
• The Iceman Cometh? exposes the human need for illusion as an antidote to despair..
• The Iceman Cometh exposes the physicist need for a goal as an antidote to building a machine/detector/computer system/simulation *
*delete as applicable• Apologies to Eugene O’Neill
• Thanks to Peter Higgs..
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Where Theory meets Experiment
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Theory: vacuum potential
Energy
The Higgs Mechanism
The ultimate green field site
Higgs potential:
V()= -2+ + (+)2
(>0)
=exp(ia(x) T’’a) |0 . (0 +
H(x))
mH = 2 (a free parameter)
Ready to interact
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
MH ≤ 1000 GeV
EW ≥ 500 GeV
E1 ≥ 1000 GeV
E2 >≥ 1000 GeV
Proton Proton Collider with Ep ≥ 7 TeV
p pq
q2
q1
q
Z0
Z0
HWW
LHC Motivation: Higgs Production in pp
Collisions
unitarity arguments
mH ≤ 1 TeV
(Lee et al, 1977)
Parton luminositiesEcm=(4x1x2.EpEp)
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
For 30 fb-1, the Standard Model Higgs can be discovered over the full allowed mass range
End of talk?
LHC Motivation: Higgs Discovery Potential
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Latest Electroweak Fits• logarithmic sensitivity to mH:
• Measured mt = 172.7 2.9 GeV
3 GeV shift in measured mt causes ~20% shift in mH
• Preferred mH = 91 GeV
• Incl. theory uncertainty gives mH < 186 GeV (95% CL)
• Does not incl. LEP2 direct search limit: mH > 114.4 GeV (95% CL)
• Renormalise probability (mH >114.4 GeV) to 100%, then mH <219 GeV (95% CL)
22 /ln ZH mm
Greater focus on the light Higgs
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Tevatron direct search
• Tevatron may be able to exclude a light Higgs (mH<130 GeV)
• Given sufficient luminosity, evidence for a light Higgs still possible
4 fb-1/expt
10 fb-1/expt
Updated in 2003 in the low Higgs mass region
W(Z)Hl(,ll)bb to include
1. better detector understanding
2. optimised analysis
Combined CDF and D0
L [fbL [fb-1 -1 ]]
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
A. When
A. When co
meth
cometh
the
the LHC?
LHC?
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
A. When cometh the LHC?Stages:• Establish injection conditions• Fill• Ramp up• Squeeze• Prepare physics• Physics• Standard beam dump• Non-trivial
7+7 = 14 TeV Ultimate design luminosity (SUPA-LHC?)L = 1034 cm-2s-1 = 10 events nb-1 s-1 or 100 events fb-1 yr-1 (continuous running)
Realistically expect?
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
LHC Startup Planning
“Main objectives are to terminate installation in February 2007 and enable first collisions in summer 2007” Lyn Evans
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
LHC Commissioning (in 4 stages)
Stage 1: Initial commissioning to pilot physics
beta* [m]Bunch
intensity Luminosity [cm-2s-1]
Event rate
/cross
1 x 1 18 1010 1027 low!
156 x 156 2 9 1010 1.1 1032 3.9Stage 2: 75 ns (Nominal emittance, full crossing angle)
936 x 936 10 4 1010 2.3 1031 0.13
936 x 936 2 4 1010 1.1 1032 0.64
Stage 3: 25 ns (Limited intensity)
2808 x 2808 4 4 1010 1.7 1032 0.32
2808 x 2808 0.55 6 1010 2.8 1033 5.2
Stage 4: 25 ns (Performance)
2808 x 2808 2 8 1010 1.4 1033 2.6
2808 x 2808 0.55 1.15 1011 1.0 1034 19.3
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
A. When cometh the LHC?Stages:• Establish injection conditions• Fill• Ramp up• Squeeze• Prepare physics• Physics• Standard beam dump• Non-trivial
7+7 = 14 TeV Ultimate design luminosity (SUPA-LHC?)L = 1034 cm-2s-1 = 10 events nb-1 s-1 or 100 events fb-1 yr-1 (continuous running)
Realistically expect? 20072007 2008 2008 20092009collisions ~2fbcollisions ~2fb-1-1 ~10fb ~10fb-1-1
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Bat 40B. When cometh B. When cometh ATLAS?ATLAS?
not where.. the detector will end up
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
The ATLAS experiment is 26m long, stands 20m high and weighs 7000 tonsSCT alone has 6.2 million read-out channels
ATLAS = large international collaboration to find the Higgs (and much more) in the range 0.1TeV < mH < 1TeV
The ATLAS Detector
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
ATLAS Status
SignificantProgress
All four completed SCT barrelcylinders have been integratedin their thermal enclosure
The barrel LAr and Tile calorimeters are in their ‘garage position’.LAr end-cap C on its way
A cosmic muon registered in thebarrel Tile calorimeter Integrated end-cap TRT wheels
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
ID B
ID A
Pixe
l
ID C
36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
EO, side A
JF
VJ
Nov '06Apr '06Dec '05 Jan '06 Feb '06
Oct '06Apr '06 Jul '06May '06 Jun '06 Aug '06 Sep '06
Chi
mne
y
Muon services
Jan '06Dec '05
Che
ck ra
ils
ID services along Barrel
Cable chains
Side C
Barrel
Side A
Sep '05 Nov '05
Feb '06 Mar '06Sep '05 Oct '05 Nov '05
Oct '05
Services 1st fix
Mar '06
JF
EO, side C
Apr '07
glob
al te
sts,
pum
p do
wn
& b
ake
out
VJ
Pixel connection and testing
VT
Glo
bal C
omm
issi
onin
g
VTVA
BMS
Rel
ease
of
jack
s
HS arches
May '07
Full
mag
net t
est?
Feb '07 Mar '07Oct '06 Jan '07Dec '06
Muon Barrel C
JD
JD
Sole
noid
Endcap Calo ASmall
Wheel A
JF
HS arches preparation JF
LAr
JT
Big Wheel A, (TGC1)
Big Wheels A (MDT+TGC2+TGC3)
JN
Endcap Toroid AEndcap Toroid A
cooldown & testing
JT?
Barrel Calo testing and commissioning
LAr
May '07Nov '06 Jan '07 Apr '07Mar '07Feb '07Dec '06
Big Wheels C (MDT+TGC2+TGC3)Endcap Toroid C
Endcap Toroid C cooldown & testing
Small Wheel C
Barrel Toroid Coils 7-8
Muon brackets & rails
Platf. Remov.
ID services through Muons
Endcap cryo lines.
Barrel Calo services
Barrel Cryo lines
Barrel Toroid servicesBT testing &
commissioningPlatforms removal
Barrel Calorimeter
services, 1st fix on truck
Big Wheels C (TGC1)
JNEndcap Calorimeter C Services
1st fix
Jun '07
Chains
Endcap Cal. A services connection, test & commissioning
Muon Barrel A
Side A closed
Endcap Cal. C services
Fiel
d m
appi
ng
Endcap Cal. C testing & commissioning
VA
ID Barrel connection and testing IDC connection and
testing
Global Commissioning
Jun '07
ID A connection and testing
Aug '06 Sep '06Jul '06May '06 Jun '06
Full magnet test
“with good will and great efforts from everybody we can be confident that the Technical Coordination Team will manage to have ATLAS installed by June 2007”
B. When Cometh ATLAS?
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Aim: by 2008 (full year’s data taking)
- CPU ~100MSi2k (100,000 CPUs)
- Storage ~80PB - Involving >100 institutes
worldwide
- Build on complex middleware being developed in advanced Grid technology projects, both in Europe (Glite) and in the USA (VDT)
1. Prototype went live in September 2003 in 12 countries
2. Extensively tested by the LHC experiments in September 2004
3. Currently 197 sites, 13,797 CPUs, 5PB storage in September 2005
C. When Cometh the Grid?
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
a. Rare Phenomena Huge Background
9 o
rders
of
mag
nit
ud
e
The Higgs
All interactions
“one in a billion events”“millions of readout channels”
b. Complexity
What is the LHC Computing Challenge?
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Meeting Analysis Requirements…
CPU
0
20000
40000
60000
80000
100000
120000
2006 2007 2008 2009 2010
Year
kSI2
K
PIC, Barcelona
FNAL, US
BNL, US
RAL, UK
ASGC, Taipei
Nordic Data Grid Facility
NIKHEF/SARA, NL
CNAF, Italy
CC-IN2P3, France
GridKA, Germany
TRIUMF, Canada
Tier-1 RAL, UK
Pledged Planned to be pledged
2006 2007 2008 2009 2010
CPU (kSI2K) 98014921234
27123943
4206 6321
585710734
Disk (Tbytes) 450841630
14842232
20873300
30205475
Tape (Tbytes) 6641080555
20742115
39344007
57106402
UNCERTAINTY [%] 10 20 30 40 50
Tier-2 UK, Sum of all
Federations
Pledged Planned to be pledged
2006 2007 2008 2009 2010
CPU (kSI2K) 380038401592
48304251
54106127
60109272
Disk (Tbytes) 530540258
6001174
6602150
7203406
UNCERTAINTY [%] 20 40 60 80 100
Requirements = Pledges
• Compare(a) Bottom
up(b) Top
down
√
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
C. When Cometh the Grid?• Service Challenges – UK deployment
plans• End point
April ’07• Context:
the virtual LHC Computing Centre
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Production ModesEcm=(4x1x2.E1E2)
VectorBosonFusion
ggH
AssociatedHbb (large backgrounds)HZ (low significance)
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
large irreducible backgrounds for tt, cc and gg decay modes, Z
ProductioProductionn
bbbb WWWW(*)(*) ZZZZ(*)(*)
▬
~
√ √ √
√ √ √√
√
▬
√
~ ~~ √ ~ ~
Decay Modes
bb
WWZZ
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Light Higgs• Various decay modes:
– mH<130 GeV: tt H l X bb
– mH<150 GeV: H
– mH<150 GeV: H
– 130< mH<2 mZ:H WW(*) l l
– 130< mH<700 GeV: H ZZ(*) l l l l
– 700< mH<1 TeV: H ZZ ll H
WW l jj
• “(no K-factors)” = conservative
5
[AT
LA
S 04 ]
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Higgs Production Corrections and Uncertainties
PDF Comparison: CTEQ6, MRST2002, Alekhin• example: σ(mH=120 GeV) @ LHC
The HO pQCD corrections to
(gg→H) are large (more diagrams,
more colour)
can improve NNLO precision slightly by
resumming additional soft/collinear higher-
order logarithms
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
ggH qqHqq ggHtt qqHV
PDFs 4 to 11% 4% 5 to 7% 4%
Energy scale
@NLO:~25%
@NLO:~4%
@NLO~15%
@NLO: ~5%
Higher orders
*
NLO:50-100%NNLO:10-20%
NLO: 10% NLO: 25%@
mt+mH/2
NLO: 30%NNLO: 3%-10%
*Increase of cross section compared to lower order (correction - not an uncertainty)
Not just LO, NLO, NNLO… also resummations
Djouadi & Ferrag,hep-ph/0310209
Ht
g
g
Catani et al, hep-ph/0306211
H
g
gthreshold logs
logN(1-M2/sgg)
σtheory ± 9%
Higgs Production Corrections and Uncertainties
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
• Complex decay channel:– One lepton (trigger)– 4 b-jets + 2 jets
Need excellent b-tagging
– Fully reconstructed t• High jet multiplicity
combinatorials
ATLAS30 fb-1
• Background:– Reducible: tt+jj, W+jets
• Extracted from data
– Irreducible: ttbb, combinatorials
• Discovery potential with 30 fb-1: MH < 125 GeV
Analysis Methods e.g. Hbb, via ttH
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
ATLAS30 fb-1
t
tb
b
NLO Background Example
the more external coloured particles, the more difficult the NLO pQCD calculation
Example: pp →ttbb + Xbkgd. to ttH the leading order O(αS
4) cross section has a large renormalisation scale dependence
the more particles, the more
difficult the whole
analysis
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Analysis Methods e.g. H
1. Radiation lengths 3. NLO corrections
2. Primary vertex 4. inc. recoil jet(all/unconverted/converted ’s)
An “easy” decay mode
(30 fb-1)
“easy” is relative
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
Combined Analysis • Requires an understanding of (all of) the individual
signals, backgrounds and the relative systematic uncertainties…
•Two or more channels in complete light mass range•Enhance early Higgs discovery? ATL-PHYS-2004-034 (2004)
•Invert the problem•“Luminosity required for discovery?” •Assume the LHC luminosity guesstimates are correct…
2008
2009
The Icemen Cometh
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
A (Light) SummaryPriors indicate a Higgs mass 114.4 < mH [GeV]
<219
A Grid service will be launched in April 2007The ATLAS detector will be complete in June 2007The LHC will provide first collisions in Summer
2007
These will enable data analyses such that the Higgs will be discovered on May 29th 2009
“Of course I like it when they give
seminars on the search for the Higgs and so on…”
probably… large corrections
12 October 2005 Particle Physics Theme Launch
Tony Doyle - SUPA
The last Barrel Toroid coil was moved into position on 25th August and the structure was released from the external supports on 29th September
How the Higgs will feel on his 80th birthday?
what have I done?
Of course I like it when they give seminars on the search for the Higgs and so on. And of course I think it's important to look for. But you want to know the truth, when I consider the huge sums going for this, the lifetimes spent on the search, I can't help but think: “Good heavens, what have I done?” Peter Higgs