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GLOBAL ELECTROWEAK FITS AND CONSTRAINTS ON THE HIGGS MASS. Pete Renton University of Oxford LEP Electroweak Working Group. status of precision Z and W boson properties top quark mass, α (M Z ) and other SM parameters agreement of data with SM ? - PowerPoint PPT Presentation
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ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
GLOBAL ELECTROWEAK FITS AND CONSTRAINTS ON THE HIGGS MASS
Pete Renton University of Oxford
LEP Electroweak Working Group
status of precision Z and W boson properties
top quark mass, α(MZ) and other SM parameters
agreement of data with SM ?
global electroweak fits and Higgs mass
Emphasis on new results since EPS Aachen Summer 2003
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Z boson properties: LEP + SLD
(f=l,c,b)
(f=c,b)
2 2f f fV Ag g
f ff 2
f f
2
1 + ( )V A
V A
g gA
g g
fFB e f
3A A A
4
epoln A ,A L R
L RR eL AA
fFBLRA A
f
results (almost!) final
ff 3
2 fVf f f eff
= T
= 1 - 4 q sin
A
A
g
g g
f
Z
-
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
CDF D0
)quantitiesk electroweaother (plus M and ,M oft measuremen tW W
new Run 1 improved Mt measurement from D0 ~100 pb-1
Run 2 prelim Mt measurements from CDF & D0 from ~160 pb-1 new
combinations (Run 1 only) by Tevatron Electroweak Working Group
s = 1.96 TeV
19th year!
_
Tevatron p p Collider
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Precision (pseudo-)observables
ll FBhad
0hZ A M
tau polarisation - Ae(1)
left-right asymm -Ae (1)
Z lineshape (5)
Z (b,c) properties (6) cbcFB
bFB
0c
0b A A A A R R
W properties (2)
top quark mass (1)
WW M Total of 17 at high Q2
(assuming lepton universality)
from > 1000 measurements with (correlated) uncertainties
2 lept hadeff FBsin (Q ) (1)
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Electroweak Corrections
40th anniversary of Peter Higgs’ papers
Standard Model parameters: )M ),M ,G ,M ZS ZF Z tM&
top-quark mass ‘predicted’ by electroweak corrections prior to direct discovery
plus ‘unknown’ HM
does this work for the Higgs ?
eg LP 1995 Beijing
SM: TOPAZ0 and ZFITTER 6.40 new
sin2θeff fermion 2-loop: MW full 2 (& leading 3)-loop
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Z boson
l
inv
SM
l
using ( / ) = 1.9912
/ = 5.942 0.016
N = 2.9841 0.008
0.0012
(1.9 b w
3
elo 3)
e
eLR
A = 0.1465 0.0033 polarisation
A (SLD) A = 0.1513
0 . 0021
other measurementsLEP lineshape results
derived quantities
leptons favour low Higgs mass
lepton couplings
= 36.5/31 df (prob = 2 % 3 )
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Combined LEP/SLD Z heavy flavour results
b(c)
hadb(c)R
(F/B asymmetries are statistics dominated)
new updates from SLD -all results & combination (almost) final
Z- b (and c) asymmetries
favour high Higgs mass
bebFB AA
4
3 A
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
W boson mass
Run 2: CDF,D0 coming soon!
LEP2
Tevatron
MW favours low Higgs mass
_
T Tp p W : m , p ( = e, )l ll l
FSI (CR & BEC) in qqqq still under study
(97 MeV com
WW qqqq & qq
qqqq has only 10
mon systematic
% of weight in
for qqq
LEP2 av
q)
erage
l
-4W WM M 4 10
final analyses still in progress
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
W boson width
W = 2.097 S 0M: 03 .0
W br. ratio is 3.0 above e - average
new final results from ALEPH & L3
W branching ratios
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
top quark mass: Run 1
D0: improved Run 1 value
) GeV 5.1 174.3 m (previous t
t tM M 2.4 %
t
m 178.0 2.7(stat) 3.3
New world average (Run 1 on
(syst) GeV
178.0 4.3 GeV
ly):
new
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
top quark mass – Run 2 (prelim)
CDF
D0
new
not yet included in world average
new
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
α(MZ)
EWWG default value – ‘data’ driven - no significant change using latest re-analysed CMD-2 and KLOE data (LAPP EXP 2004-4) also use a more ‘theory’ driven value
(5)had
) = 1 - ( ) - ( ) - ( ) l top
ss s s
2
''had
had ' '4m
R ( ) = - P
3 ( )
ssds
s s s
(5)had Z(M ) = 0.02761 0.00036
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
2V Asin = (1 - g /g )/4lept
eff l llong standing (and a-posteriori) observation of difference between:
2
2
sin = 0.23113 0.00021
sin = 0.23213 0.00029
leff
leff
leptons
hadrons
2.8 difference (0.3% probability)
essentially from difference ofb
e FBA (SLD) & A (2.8 )prob = 8.4%
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
THE BLUE BAND PLOTGlobal electroweak fit – high Q2 data
Since Aachen EPS Summer 2003
new top mass increases mH by ~20 GeV
new 2-loop terms etc increase mH by ~6 GeV
t
S Z
+ 69H - 4
2
5
H
m = 178.2 3.9 GeV
(M ) = 0.1186 0.0027
m = 114
= 15.8/13 df (prob = 2
GeV
m < 260 GeV (
6
95 )
%)
% cl
new
(5)had Z Hfor (M ) = 0.02749 0.00012 m 129 GeV
2W H
from uncertainties of 2 (& leading 3)
loops for M & sin (main ef
'bl
fec
ueb
t f
and'
or m )eff
Awramik,Czakon,Freitas,Weiglein hep-ph/0311148,0407317 &refs therein
Faisst,Kuhn,Seidensticker,Veretin N Phys B665,649(2003) + many more!
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Higgs mass from individual measurements pulls
direct search limit
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
mt , mw direct vs indirect
direct mt and mw
indirect mt and mw
reasonable degree of overlap
powerful test of SM
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
progress since Lepton Photon 95 in Beijing
2004 indirect mt and mw
2004 direct mt and mw
1995 direct mt and mw
1995 indirect mt and mw
68% cl
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Moller scattering
E158 SLAC
t)0.0012(syst)0.0011(sta 0.2330 sin MSW
2
polarised e- beam – measure right-left parity violating asymm. APV (accuracy ~3 10-8)
Atomic Parity Violation (APV)
y)0.36(theor 0.29(expt) 72.74- (Cs)QW (SM -72.93)
Woods et al, Sci. 275 (1997) 1759; Ginges & Flambaum, physics/0309054
Measurement of weak charge in 133 Cs
hep-ex/ 0312035, 0403010 & E158 website
Q2 ~ .03 GeV2
(prelim)
Q2 ~ 5 10-5 GeV2
new
(SM 0.2310)
new
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
NuTeV experiment
Measure R = NC CCfor and -Q2 ~ 15 GeV2
0.0016 0.2277 MM - 1 sin 2Z
2WW
2
for mt = 175, mH = 150 GeV
meas. Mdirect from 1.3 W
New physics? : Z’, contact int., lepto-quarks,
new fermions, neutrino oscillations . …
or old physics ?: pdf’s uncertainties in LO, isospin violation, s-sea asymm., shadowing,
QED corrections (hep-ph/0310364) …
fit also including low Q2 data
SM
R( )
_
R( )
mH 128 GeV ( +14 GeV)
prob of fit 5.4 % pull (NuTeV) = 2.9
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
summary
steady progress on both experiment & theory fronts
although still issues with AFB(b) and NuTeV results (both ~3sigma effects) SM gives satisfactory fit to large amount of data. Clarification desirable – but how & when?
fits favour relatively light Higgs (<260 GeV@95% cl)
current best value is
improved mt and mw values eagerly awaited
69H 45m = 114 GeV
THANKS to the EWWG, especially Martin Grünewald
What is the Higgs mass?
the future ?
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
what I didn’t have time for
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
results internally consistent
hadronic couplings of Z
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
bebFB AA
4
3 A
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
b and c-quark couplings
2 2Vb(c) Ab(c) Ve Ae Vb(c) A
b(c)b( b(c) e b(c) FB c)R A (LEP,SLD) g g g / g g / g A & A
marginal (~3%) agreement with SM for b-quark (mostly in the r.h. coupling)
SM for b & c insensitive to variations in mt and mH
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
Combined LEP/SLD heavy flavour results
b cFB FBenergy dependence of A and A
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004
low Q2 experiments