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

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


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

-


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


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)


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


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 )


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


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


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


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


top quark mass – Run 2 (prelim)

CDF

D0

new

not yet included in world average

new


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


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%


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!


Higgs mass from individual measurements pulls

direct search limit


mt , mw direct vs indirect

direct mt and mw

indirect mt and mw

reasonable degree of overlap

powerful test of SM


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


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


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


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 ?


what I didn’t have time for


results internally consistent

hadronic couplings of Z


bebFB AA

4

3 A


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


Combined LEP/SLD heavy flavour results

b cFB FBenergy dependence of A and A


low Q2 experiments

ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004...

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Transcript of ICHEP04 Beijing Global Electroweak fits and constraints on the Higgs mass Pete Renton Aug 2004...