Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 1
Electroweak Physics: Results from Experiments and Interpretations, Complementarity with future LHC Results, Precisions to be reached
(Experiment)
Michael RoneyUniversity of Victoria
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 2
Outline• Reminders of the standard model
• LEP & SLC precision neutral current electroweak data
• LEP & Tevatron Electroweak Data
• Electroweak Expectations from LHC
• Summary
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 3
Z-fermion CouplingsEW Z W Higgs
f f 5Z V A
W W
...
( ) Z2sin cos f f
e g gγ
µ µµψ γ γ γ ψ
θ θ
= + + + +
−∼
L L L L L
L
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 4
standard model Parameters • 12 fermion masses; mixing matrix parameters (4
quark; 4 lepton), strong phase, and the following 5 precision parameters
Møller, APV
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 5
note on “derived parameters”• experimentalists view: choose the most
precisely determined independent parameters to ‘define’ the standard model
• derive other standard model parameters:
22
2
2
1sin 1 1 42 2
1 1
/(1 ) radiative corrections
42 2
QEDW
F Z
QEDZW
F
QED QE
Z
D
G mmm
G mr
r
παθ
π
α
α
α
= − −
= + −
→ −∆∆
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 6
2 22
2 22
(0) 1
In particular choice of renormalization scheme the form of the SM relation:
i
cos sin12
(0) 1cos preserve
s
( ) (
sin12
)
:
(
d
)
W WZ F
f
e top
feff eff f
Z F
wf f
W
rm G
rm
s s s
Gr rr r
µτα α α
παθ θ
παθ θ
αα
α
=−∆
=−∆
∆ = ∆ + ∆∆ = ∆ + ∆∆ = ∆ + ∆ + ∆ )
2
2
(5 ( )(0)( )
1 ( )...
cos ...sin
fW
W
h
w
a
W
d s
ss
r
r
ρ
θ
α
ρ
αα
θ∆ = −∆ +
∆ = − ∆ +
=−∆
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 7
Radiative corrections give sensitivity of precision measurements to the top and
Higgs mass
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 8
Z-lineshape: MZ and ΓZ
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 10
Neutral Current Asymmetry Parameters
( )( )
( )
2 2V AR
2 2R V A
V A2
V A
lept2V A eff
2 +
2 /
1 /
/ 1 4 sin
L
L
g gg gg g g g
g g
g g
A
g g θ
−= =+
=+
=• −
� �� �
� � � �
� �
� �
�
� �
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 11
Z-fermion Couplings• Neutral current parity violating observables are
sensitive to sin2θW : asymmetries give gV/gA� Left-right asymmetries at SLD: ALR
� Forward-backward asymmetries at LEP: AFB
� Tau polarisation measurement at LEP
• gA is measured from cross sections: Rl
• Major focus of LEP and SLD on this sector of the standard model
• APV• Møller Scattering
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 12
SLAC Linear Collider (SLC)e+e- Collider with one experiment:
SLAC Linear Detector (SLD)Centre-of-mass at Z-pole 1992-1998
• electrons were longitudinally polarised
• 300k left-handed & 240k right-handed
• polarisation precisely measured
• 73%-77% for most of the data set
• Primary measure:
ALR= (NL-NR) / (NL+NR) x (1/<Polarisation>) = Ae = 0.1513±0.0021
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 13
LEP 27km circumference e+e-synchrotron storage ring collider
1989-95 LEP 1 Z-pole: 3.5M Z decays per exp’t1995-00 LEP 2 WW: O(1000) W-pairs
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 14
Z couples to all fermionse.g. tau-pair production
AFB= (NF-NB)/(NF+NB)
tree-level diagram:
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 15
Observables sensitive to couplings at LEP
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 16
Z ( ) (hadrons)qq g→
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 17
Z bb→0,bFB
All LEP measurements are consistent4 A(LEP only) 0.881 0.0173
(SLD) = 0.923 0.020Agree at 1.6
(LEP+SLD)=0.889 0.013 (0.935 0.001 SM)3.5
b
b
b
AA
A
Aσ
σ
= = ±
±
±±
�
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 20
Z →e+e-; µ+µ-; τ+τ-
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 21
+Tau Polarisation: e e Production τ τ− + −→
( )( )
( )
2 2V AR
2 2R V A
V A2
V A
lept2V A eff
2 +
2 /
1 /
an
d
/ 1 4 sin
Lepton universality:
L
L
e
g gg gg g g g
g g
g g
A
g g
A Aτ
θ•
−= =+
=+
= −
•
� �� �
� � � �
� �
� �
�
� �
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 22
total
P
P P - P
Measure the Polarization τ
τ τ τ
σ σσ
σ σσ σ
− +
−+ + −
+ −
− −= =
≡
+
=
( )( ) ( )
( ) ( ) ( )
2 FBFB pol
total
2 FBFB pol
total
total
po
1 3 81 P 1 cos A A cos cos 16 3
1 3 81 P 1 cos A A cos cos 16 3
P = averaged over cos
A
dd
dd
τ τ ττ
τ τ ττ
τ τ
σ θ θσ θ
σ θ θσ θ
σ σ θσ
− −
−
− −
−
−
+
−
+ −
= + + + +
= − + + −
−
[ ] [ ] [ ] [ ]cos 0 cos 0 cos 0 cos 0FBl FB
total total
A τ τ τ τθ θ θ θ
σ σ σ σ σ σ
σ σ− − − −
+ − + −> < > <− − − −
= =
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 23
FBpol FBe e A3
4P 3
4AA A A Aτ τ τ= = − =−
( )( )
( )( )
FBpo
2 2
22
l
FB
81 cos cos 1 cos 2 cos3P (cos ) 8 1 cos 2 cos1 cos cos
P A
A3
e e
A AA A
τ τ τ ττ τ
τ ττ τ
τ θ θ θ θθ
θ θθ θ
ττ
− −− −
−
− −− −
+ + + += = −
+ ++ +
pure Z0 exchange at the pole
Lines assumeLEP average
solid: no lepton universality assumed
dashed: assumelepton universality
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 24
Compare different sin2θW Measurements
Prob=3.8%
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 25
Hadron Vacuum Polarisation [slides: Davier at Tau06’]
Define: photon vacuum polarization function Πγ(q2) ( ) ( )†4 2 2
em em0 ( ) ( ) 0 ( )iqxi d x e TJ x J x g q q q qµ ν µν µ νγ= − − ∏∫
Ward identities: only vacuum polarization modifies electron charge
(0)( )1 ( )
ss
ααα
=− ∆ ( ) 4 Re ( ) (0)s sγ γα πα ∆ = − ∏ −∏ with:
Leptonic ∆α lep(s) calculable in QED. However, quark loops are modified by long-distance hadronic physics, cannot (yet) be calculated within QCD (!)
Way out: Optical Theorem (unitarity) ...
(0)
(0)[ hadrons]12 Im ( ) ( )
[ ]e es R s
e eγσπσ µ µ
+ −
+ − + −→∏ = ≡→
( )2(0)Born: ( ) ( ) / ( )s s sσ σ α α=
Im[ ] ∝ | hadrons |2... and the subtracted dispersion relation of Πγ(q2) (analyticity)
0
Im ( )( ) (0)
( )sss ds
s s s iγ
γ γ π ε
∞ ′∏′∏ − ∏ =′ ′ − −∫ had
0
( )( ) Re3 ( )
s R ss dss s s i
ααπ ε
∞ ′′∆ = −′ ′ − −∫
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 26
Compare different sin2θW Measurements2
2
2
2
2
sin from only
leptons 0.23113 0.00021 Prob( ) 0.45 hadrons 0.23222 0.00027 Prob( ) 0.99
sin (leptonic
only LEP=0.23136 0.00032
couplings only)
sin (leptonic&hadr
lepteff
lepteff
lepteff
θ
χχ
θ
θ
± =
± =
−
±
( ) ( )
LR0,bFB
onic couplings)_______________________________________= 0.23113 0.00021 0.23222 0.00027= 0.00109 0Note: if A is ignored, still get -2.0 if A is
.00034
ignore
De
d,
3
spi
get
.2
6
te
-1.σ
σ
σ± − ±
− ± ⇒
0,bFB
tremendous effort looking for unaccounted systematic effect, particularly for A , none Remaining Possibilities: statistical fluctuation
has been
sign of
iden
new
tified
physics••
new leptonmeasurementsshould be atleast 0.00021to have a big impact(apart fromtesting running)
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 27
Standard Model Fits: Summer ‘06
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 28
Standard Model Fits: Summer ‘06
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 29
Runningof sin2θθθθW
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 30
Z0 EW Precision sin2θW→ Mtop
precision Mz and asymmetry
measurements at LEP/SLD predicted
Mtop years prior to
the Tevatron discovery.
An important milestone in
EW physics: quantum field
theory can successfully
describe weak interaction physics
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 31
Predicting MHiggs
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 32
Measuring sin2θW at LHCAFB in Drell-Yan can be used to measure sin2θW
qFB e
3A 4 qA A∼( )
22 * *
0 1*
0 1
@ LHC p-p collisions q is a sea-quark q is a valence quarkAt parton level in CM:
ˆ1 cos cos
cos 4& determined by EW couplings of
d A Ad sA A
σ α θ θθ
→
= + +
2
0
1FB
2*
0
initial- and final-state fermions
ˆ~ New Physics
cosNew Physics obse
4ˆ3 "observable
rvable in amplit
s"3A
ude or interference with &
8
Z
s s
A
Z
As
dA
dσ γθ
πασ
γ
=
=
+
+
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 33
Measuring sin2θW at LHC
( )
( )1
1 2
2
/ 1
21 2
1 2 1
/ 2 / 1 /
2
2
parton distribution functions (PDFs)
(
Partons cross sec
) ( )
tions folded with
ˆ : cross section for
ˆ : inva
ˆ
ˆ
riant mass of
( ) ( )
i p j p j p i pij
f x f x f x f x
d ppd
q q
M s s
M dyσ
σ
τ
σ
→
+
→
= =
∑
� �
� �
�
�
∼
�
�
�
1 2
1 2
1 2
2
/
1
1 ln : rapidity of 2
parton momentum fraction
( ) : probability to find parton with momentum fraction in the p
s
rotonk
y
i k
Z
y
p
Z
E pyE p
x
f x i
e
x
x
e
τ
τ −
+= −
=
=
� �
�
� �
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 34
Measuring sin2θW at LHCRecall particle production is ~constant as function of
1 rapidity, y= ln2
difference in rapidity of two particles is independentof Lorentz boosts along the beam axisAt the parton level
Z
Z
E pE p
•
+ −
•
, these boosts are unknown at hadron colliders
Pseudorapidity, , is numerically close to y, but is onlydependent on the angle relative to the beam axis,
ln tan2
ηθ
θη = −
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 35
Measuring sin2θW at LHC
*FB
1 1* *
F B0 0
F-BFB
F+B
A defined in terms of cos , with respect to q directionIn p-p collisions at LHC, dir
( , ) cos c
ection
os
( , )A ( , )( , )
of q needs to be inferredfrom kinematics
y M d d
y My My M
σ σ θ σ θ
σσ
θ
± = ±
=
∫ ∫�� ��
�
�
of system:antiquarks come from sea, quarks are valence or sea
boost direction preferentially along quark directirapidity is used as measure of quark direc ion
ot
n
+ −
+ −
⇒
⇒
� �
� �
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 36
Measuring sin2θW at LHC
4
2085.2 ( ) 97.2at least 1 electron with 2.5 :
Electron ID eff. ~70%; jet rejection >10allow 2nd electron up to 4.9 :Electron ID eff. ~50%;
cut dependent jet rejection
electronTp GeV
GeV M e e GeVη
η
η
+ −
>
< <≤
≤
−
ATLAS study by Sliwa,Riley,Baur reportedin hep-ph/0003275 using PYTHIA 5.7 & JETSET 7.2
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 37
Measuring sin2θW at LHC
Dependence of AFB on rapidityat LHC andηηηη
cuts on electron
note: AFB fromΖΖΖΖ−−−−>>>>
µµµµ++++µµµµ−−−− as for|η|<2.5|η|<2.5|η|<2.5|η|<2.5
for both µµµµ
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 38
Measuring sin2θW at LHC( )( )
3
3
2 2FB
( )
( )
A sin lepteff Z
O Born QED QCD
O Born QED QCD
b a M
a a a a
b b b b
α
α
θ= −
= + ∆ + ∆
= + ∆ + ∆
Connecting
to sin2θθθθW:
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 39
Measuring sin2θW at LHC
µµµµµµµµ
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 40
Measuring sin2θW at LHCSystematic uncertainties:
•PDFs: lepton acceptance & radiativecorrections
•Lepton acceptance & reco eff vs Y(need <0.1%, PDFs an issue)
•Higher order QCD & EW corrections•Mass Scale (AFB varies with lepton pair
mass)
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 41
Measuring sin2θW at LHCSystematic uncertainties:Biggest worry is•PDFs: lepton acceptance & radiative
correctionsStudied by PDFs (MRST, CTEQ3, CTEQ4)stat. limited study suggests agreementat ~1% on Afb [but these PDFs are correlated]. Moreover, need x~10 better error, to keep it small cf stat error.(note: this is more demanding than for AFB
0.b
since the sensitivity to sin2θθθθW, b factor, is much lower.)simultaneous fits for sin2θθθθW and PDFs?
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 42
Measuring sin2θW at LHCAssume something approachingthe statistcal error can be achieved:
this is in fact complementary to thee-e- measurement because it is sensitiveto quark and lepton couplings, not just lepton couplings: if LEP/SLD “discrepancy”is from new physics AND related to quark vs lepton NC couplings,that new physicsshould show up here as well:this LHC measurement is ~ QFB
had at LEP
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 43
Measuring sin2θW at LHC
But LHC will alsomeasurement theasymmetry wellabove the Zmeasuremests at several % level [M.Dittmar PRD 55 ’95]
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 44
Mw @ LEP & Tevatron• Current Mw measurements
give EW constraints on e.g. MHiggs… complementary to sin2θW
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 45
• Current Mtop measurements give EW constraints on e.g. MHiggs complementary to sin2θW
Mtop @ Tevatron
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 46
Mw@LEP and Mw&Mtop@Tevatron• Mw & Mtop give
complementary EW constraints on e.g. MHiggs
independent of
sin2θW measurements
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 47
Mw at LEP & Tevatron• Mw & Mtop give
constraints on Mhiggs…complementary to sin2θW
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 48
Mw at LHC expected• Mw & Mtop give constraints on Mhiggs…
complementary to sin2θW
• Uncertainties are expected to be significantly smaller than LEP & Tevatron values
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 49
Mw at LHC
from M. MalberiICHEP ‘06
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 50
Mw@Tevatron: reality check for LHC
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 56
Mw at LHC Uncertainty on Mass will be dominatedby systematics, many of which (suchas PDFs,energy scale and resolution)will be determined and themselves limited by statistics.The GOAL of 15MeV/c2 looks verychallenging at this point, but achieving~20MeV/c2 can likely be reached
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 57
Top production at the LHC~90%~90%
~10%~10%
1. 1. tttt is an essential process for is an essential process for commissioning detector and toolscommissioning detector and tools•• jet energy scale, bjet energy scale, b--tagging calibrationtagging calibration
Production (diff.)Production (diff.)crosscross--sectionsection
t masst mass
W, t W, t helicitieshelicities
Decay modesDecay modes
Light jet Light jet energy scaleenergy scale
bb--taggingtagging
bb--taggingtagging
2. 2. tttt is a fundamental process for is a fundamental process for electroweak (precision) measurementselectroweak (precision) measurements•• the top quark is interesting per se (mthe top quark is interesting per se (mtt~190m~190mpp!)!)•• mmtt, , σσtt, q, qtt, , VVtbtb ,, σσtttt, , BRBRtt, , tttt, , pdfspdfs•• mmtt can greatly help in the indirect constraint can greatly help in the indirect constraint
of the Standard Model (and new physics !)of the Standard Model (and new physics !)
~100%~100%
3. 3. tttt is a fundamental process for the is a fundamental process for the direct search of new physicsdirect search of new physics•• both production and decay: both production and decay: XX→→tttt, , tt→→XX, , ttXttX•• larger couplings with Higgs larger couplings with Higgs ––new physics?new physics?--•• top is background to many search channelstop is background to many search channels
The LHC will be a topThe LHC will be a top--factory !factory !•• σσNLONLO~830 ~830 pbpb : : 2 2 tttt events per second !events per second !•• more than 10 million more than 10 million tttt events expected per yearevents expected per year•• first physics in 2008 !first physics in 2008 !
from R. ChiericiICHEP ‘06
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 58
~4.1~4.1~4.0~4.0~0.7~0.7~0.1~0.1via crossvia cross--sectionsection
~1.1~1.1~0.6~0.6~1.0~1.0~0.2~0.2bqqbbqqbℓℓνν
~1.5~1.5~1.4~1.4~0.5~0.5~0.5~0.5exclusive exclusive J/J/ψψ decaysdecays
~4.2~4.2~3.5~3.5~2.3~2.3~0.2~0.2bqqbqqbqqbqq
~1.2~1.2~0.3~0.3~1.0~1.0~0.5~0.5bbℓℓννbbℓℓνν~1.7~1.7~1.4~1.4~0.9~0.9~0.2~0.2bqqbbqqbℓℓνν high high ppTT
δδmmtt
(GeV/c(GeV/c22))δδmmtt(s(systyst. . thth.).)
(GeV/c(GeV/c22) ) (2)(2)
δδmmtt(s(systyst. . instrinstr.).)(GeV/c(GeV/c22) ) (1)(1)
δδmmtt(s(stattat))(GeV/c(GeV/c22))
The key points for reducing the error on The key points for reducing the error on mmtt will be:will be:•• reduce systematic by using data to calibrate our measurements anreduce systematic by using data to calibrate our measurements and to d to
constrain our knowledge on simulationconstrain our knowledge on simulation•• combine analyses with a different systematic breakdown combine analyses with a different systematic breakdown
→→ many instrumental systematic errors are analysis correlatedmany instrumental systematic errors are analysis correlated→→ most theory systematic errors are also ATLAS/CMS correlatedmost theory systematic errors are also ATLAS/CMS correlated
⇒ ⇒ 1 GeV/c1 GeV/c22 error is anyway in reach !error is anyway in reach !
(1) jet and lepton energy scales, b(1) jet and lepton energy scales, b--tagging, luminosity,tagging, luminosity,……(2) radiation, fragmentation, MB/UE,(2) radiation, fragmentation, MB/UE,……
Estimated sensitivities as of today:Estimated sensitivities as of today:
LHC mt error breakdown from R. ChiericiICHEP ‘06
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 59
mmHH
SUSY mass scaleSUSY mass scale
MSSM MSSM ≈≈ SM SM
•• The experiments have now presented their realistic potential onThe experiments have now presented their realistic potential on top physics top physics measurements. Many ideas around on how to determine the top mmeasurements. Many ideas around on how to determine the top mass.ass.
•• By cBy combining all analyses, an estimation of ombining all analyses, an estimation of δδmmtt~1GeV/c~1GeV/c22 is realistic and totally is realistic and totally dominated by systematic error. dominated by systematic error.
→→ Conservatively estimated, especially when due to theoretical unConservatively estimated, especially when due to theoretical uncertaintiescertainties→→ The use of data for understanding detector and simulation will The use of data for understanding detector and simulation will be essentialbe essential
•• A precise measurement of the top quark mass willA precise measurement of the top quark mass willallow to:allow to:
→→ improve detector understandingimprove detector understanding→→ constrain standard physicsconstrain standard physics→→ look for presence of new physicslook for presence of new physics→→ constrain new physics !constrain new physics !
Impact of LHC W and Top measurements
Assuming Assuming δδmmWW=15 MeV/c=15 MeV/c22 and and also also ∆α∆αhadhad=0.00012=0.00012
→→ ((δδmmHH/m/mH H ≈≈ 25%)25%)
⇒⇒ Chances of ruling out the SMChances of ruling out the SM……
from R. ChiericiICHEP ‘06
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 60
Complementarityof sin2θWMeasurement
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 61
LHC expected to measure MHiggsComplementarity withprecision EW: predict MHiggs with precision, just as Mtop was predicted; if Mtop not where Z0 analysessaid it should be…then something else is in those loops
Similarly, if EW predictions of MHiggs are not verified byLHC measurement… something very exciting is up
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 62
Møller sensitivity to MHiggs
from E158PRL 95(2005) 081601-1-5
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 63
Møller sensitivity to MHiggs
for projectederror of 2.5E-4
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 64
Møller sensitivity to MHiggs
for projectederror of 2.5E-4and no ααααhad
(5)(Mz)error
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 65
Møller sensitivity to MHiggs
from E158PRL 95(2005) 081601-1-5
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 66
Møller sensitivity to MHiggs
for projectederror of 2.5E-4
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 67
Møller sensitivity to MHiggs
for projectederror of 2.5E-4
but…new leptonmeasurementsshould be atleast 0.00021to have a big impact, beyondtesting for running
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 68
Additional (obvious) note on complementarity Møller and
High Energy Measurements of sin2θW
As experimentalistswe want to verifythe running asprecisely as possible,new physics could liein failure of thisrunning
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 69
Summary• Z0-pole measurements from LEP and SLC provide the
highest precision measurements of sin2θW but still make one uncomfortable:
Success of predicting top mass; yet there is a chance that the AFB
0,b is telling us something about new physics
• New precision measurements in leptonic-hadroniccouplings will come with AFB in Drell-Yan at the LHC
• Additional precision measurement in purely leptoniccouplings will be very useful to reinforce the LEP and SLC leptonic asymmetry data.
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 70
Summary• Additionally, very high energy LHC asymmetries and c
Møller measurements complementary to investigate running of a possible new effect
• Want to confront Higgs discovery at LHC with highest precision EW data possible: is it SM Higgs?
• LHC expected to give higher precision
top and W masses
• Much more precise sin2θW would be very usefulto help sort out what new physics might be at the LHC (but need improved ∆α(5)
had(Mz) to get there!)
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 71
Additional Slides
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 72
2
0 2 2
f 20 3 f
20 f
f0 3
2
f
2
determined by Higgs structure (e.g.=1 if only Higgs doublets)cos
(T Q sin )Q sin
or equivalently
(T 2Q
2 sinW
treeZ W
tree treeL Wtree treeR W
tree tree tr
F treeW W
eeV L R
mm
gg
g g g
Gm
ρθ
ρ θρ
θ
θ
πα
ρ
=
= −= −
= + = −
=
2
f0 3
2
0 2 2
sin )T
Modified by radiative corrections to propagators and vertices.In 'on-shell' renormalization scheme, keep form of
cosand use this to define the o
treeW
tree tree tree treeA L R R
W
Z W
g g g g
mm
θρ
ρθ
= − = =
=
Wn-shell EW mixing angle, , to all orders in terms ofW and Z masses.
θ
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 73
f f
fVf 3
Bulk of corrections to the couplings at the Z-pole absorbed into complex form-factors: for overall scale and for the on-shellEW mixing angle, these give complex effective couplings:
(T 2f= −
R K
G R 2f f
fAf 3
flavour-dependet vertex
propagator self energy correction
Q sin )T
In terms of the real parts
( ) 1 +
( ) 1
se
W
f
f f f
f f
RE
RE
ρ
θ
ρ ρ
κ
↓↓
=
≡ +
≡ +
∆= ∆
=
K
G R
R
K + se fκκ∆ ∆
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 74
2 2
f 2Vf 3 f
fAf 3
2Vf Vff
Af Af
H W
The effective EW mixing angle and real effective couplings aredefined as:sin sin
(T 2Q sin )T
So that:g 1 4 Q sing For m m the leading order
feff f W
ff eff
f
feff
gg
RE
θ κ θρ θρ
θ
≡≡ −≡
= = −
G
G
�
2 2 2 2
2 2 22
2 2 2 2
2 2 22
terms are:
The flavour dependent terms are small ex
3 sin 5ln ... cos 68 2
3 cos 9 5ln ... sin 1
cept
0 68
for b- r s
2
qua k .
F W t W Hse
W W W
F W t W Hse
W W W
G m m mm m
G m m mm m
θρθπ
θκθπ
∆ = − − +
∆ = − − +
Electroweak Workshop: High Energy Experiments JLAB Dec 2006 J.M.Roney, Victoria 75
2 22
2 22
2
(5)
(0) 1cos sin12
(0) 1cos si
The form of the SM relation is
n
p
12
.
( ) ( ) ( ) ( )(0)( )
1 ( )
reserve
..
d:
cos
W WZ F
f feff
e top had
eff fZ F
wf f
W
fW
Ww
rm G
rm Gr r
sr r
s
r
s
ss
r
sµτ
παθ θ
παθ θ
αα
α α α ααα
θ
αρ
=−∆
=−∆
∆ = ∆ + ∆∆ = ∆ +∆∆ = ∆ + ∆ + ∆
∆ =
=−∆
−∆ +
∆ = −
22
2
2 ...sin
often used to express the W mass in terms of more preciselydetermined paramete
11 1 42 12
rs:Z
W
W
F Z
mmrG m
ρθ
πα = + −
−
∆ +
∆
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