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DELPHI status report. Roberto Chierici. CERN, EP division on behalf of the DELPHI collaboration.  The final data and simulation reprocessing  Status of LEP2 measurements and searches  Status of LEP1 measurements  Outlook. LEP jamboree, 28th February, 2002. v d /v d =10 -4.

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cern ep division on behalf of the delphi collaboration

DELPHI status report

Roberto Chierici

CERN, EP division

on behalf of the DELPHI collaboration

 The final data and simulation reprocessing

 Status of LEP2 measurements and searches

 Status of LEP1 measurements

 Outlook

LEP jamboree, 28th February, 2002

final data reprocessing

vd/vd=10-4

Final data reprocessing

cm/s

 New TPC corrections

distortions corrected by physical

parametrization of defects

offline correction of the time

dependence of drift velocity

 New VD alignment (+detector)

 Same tracking code now for all

years

consistent treatment of data

ideal for study of systematics

corrected

online database

Roberto Chierici - DELPHI status report

b tagging improvements

new/old

5-10% improvement in pure b region

b-tagging improvements

 The latest reprocessing include new

alignment

 new tuning of the b-tag at the Z

DELPHI

Ecm=206.5 GeV

Zbb

Zqq

Check DT/MC agreement on h.e. with

an independent sample

Check data with data:

 ratio of cumulative distributions

includes IP, mSV, ESV(ch), ytracks, pT,SV, pT() info

Roberto Chierici - DELPHI status report

final mc setup
Final MC setup

Big effort for choosing the best setup for our measurements:

2-fermion

  • Use of KK2f to improve DT/MC agreement
    • ISR-FSR interference effects to

O(2) included

    • Better treatment of ISR

Real

4-fermion

LEP2 MC workshop gives us new tools for

including O(EM) in CC03 physics (DPA):

(RacoonWW, YFSWW)

Virtual correction

relevant effect (~2%) on WW, d/dW

 Review our 4f generation to include

DPA without losing other features

Roberto Chierici - DELPHI status report

delphi strategy for 4f generation i
DELPHI strategy for 4f generation (I)

Keep the best features of DPA calculations and 4-f generation

CC03 issues

 inclusion of DPA

 non-diagonal CKM

 ISR with pT, FSR

4f issues

 running of EM

 IFL for We

 t-channel ISR

 low mass qq resonances

 efficient integration

(access more phase space)

(1S)

(2S)

m(qq) (GeV)

WPHACT*+YFSWW

*adapted by DELPHI

Roberto Chierici - DELPHI status report

delphi strategy for 4f generation ii

hadronization

DELPHI strategy for 4f generation (II)

Only WPHACT to exploit the largest phase 4f phase space in an efficient

way (only  regions are generated independently)

 one shot generation

 much looser generation cuts

 reweight events to any desired subprocess

from YFSWW

DPA is included through event weights from YFSWW:

4f

wDPA with

YFSWW

PYTHIA

BDKRC

TWOGAM



WPHACT

|Mi|2/|M4f|2

wTGC

|M4f(mW,W)|2

Full simulation production: 175M MC events on tape in ~190 days !

Roberto Chierici - DELPHI status report

lep2 measurements
LEP2 measurements

2-fermion production

heavy flavours

mW

WW

(N)TGC

final state interactions

4-fermion non-CC03

ZZ

Zee+We

Z*

 physics

WW

We

 finalising results...

Roberto Chierici - DELPHI status report

anomalous tgc i

f1

11

f2

W-

e-

e+

f3

W+

W

22

f4

Anomalous TGC (I)

Test SM predictions for WWZ/WW interactions

Assuming C, P, gauge invariance only 3 independent parameters describe

deviations from SM: g1z, , 

DELPHI PRELIMINARY

 WW and angular variables

sensitive to couplings

189 GeV

WW(qq)-,+()+,-

WW(qiqj)Qjet (qkql)Qjet

We qqe, e

DPA

 =+0.5

 =0 (SM)

  • For preliminary results:
  • qq - BML fit to cos(W+), cos(-), W+,-
  • qqqq - EML fit to cos(W-)
  • Other analysis in progress:
  • OO nearing completion in qq
  •  improve final precision

 =-0.5

cosW+

Roberto Chierici - DELPHI status report

anomalous tgc ii

qqqqqqWe combined

Anomalous TGC (II)

Preliminary results from all LEP2 data (~700 pb-1: 2400 qq, 5000 qqqq, 300 We)

qq

PRELIMINARY

Systematics error included:

bck,detector, fragmentation, theory

 0.01 for g1z, , 0.07 for 

But still measurement is dominated

by statistical errors

DPA inclusion has changed the limits

by about -0.5(stat+sys) ( most sensitive)

No deviations from SM

combined

Roberto Chierici - DELPHI status report

zz production cross section

e-

e-

Z

Z

Z

e+

e+

Z

ZZ production cross-section

Test the SM in the 4-f NC sector, check important background to Higgs

Measure ZZ like final states, then correct to determine NC02

Final state BR technique backgrounds

qqqq 49% fit to likelihood WW, qq()

qq 14% cut based WW

qq 28% IDA WW, We, qq()

  4% cut based WW

  1% cut based 4-f non resonant

2000

Systematics: qq modelling (hadronization,

gbb), lepton id., detector

1998

All data can be combined to increase precision

(energy correlation taken into account):

1999

YFSZZ

RZZ=exp/th=0.9 0.08stat 0.02syst

(theory error excluded)

Roberto Chierici - DELPHI status report

photon structure function

4EtagEbeamsin2(tag/2)

Photon structure function

Measure F2(x,Q2) from LEP1 and LEP2 data:

3 GeV2/c4 < Q2 < 2600 GeV2/c4

etag

RPC

QPM

VDM

Unfolding procedure:

TWOGAM, PHOJET, PYTHIA

From Q2, mhad

(QPM+VDM+RPC)

 major uncertainty from systematics

due to data description by simulation

 LEP1/LEP2 data consistent with

linear behaviour F2log(Q2)

Roberto Chierici - DELPHI status report

s matrix fit to lep1 and lep2 data
S-matrix fit to LEP1 and LEP2 data

Model independent approach to describe e+e-2f cross sections and asymmetries

LEP1+LEP2 data are now used to fit the 16 (8 assuming lepton universality)

free parameters

Jhadtot

f-b(h,e,,),tot (h,e,,) at LEP1 (final)

f-b(h,,),tot (h,,) at LEP2

For the first time use all statistics

 significant improvement using LEP2 data

as well (Z interference information)

 Jhad in agreement with SM in a

more convincing way

mZ(GeV/c2)

Roberto Chierici - DELPHI status report

lep2 searches
LEP2 searches

SM Higgs

MSSM Higgs

H++

MSSM scan (SUGRA)

GMSB SUSY

AMSB SUSY

RPV

Exotica

Technicolour

FCNC

Excited leptons

Leptoquarks

 finalising results...

Roberto Chierici - DELPHI status report

gmsb i

~

G

m

~

~

Ldecay(NLSP)

tag

G

G

~ eVLdettracks from VTX

O(1-102) eV~Ldetkinks, large IP

>O(102) eVLdetstable charged particles

GMSB (I)

is the LSP

Ldecay(NLSP) depends upon m

PRELIMINARY

Roberto Chierici - DELPHI status report

gmsb ii

~

G

m

< 1eV/c2

GMSB (II)

Free parameters: F, , M, n, tan, sign()

n=1

determines who is the NLSP

n>1

Effective SUSY breaking scale

PRELIMINARY

(all data combined)

Scan in 5D for exclusion

combining all channels

Excluded regions

> 86 GeV/c2 (95% CL)

> 17.5 TeV/c2(95% CL)

Roberto Chierici - DELPHI status report

slide16

> 70 GeV/c2 -95% CL-

> 100 GeV/c2 -95% CL-

AMSB

Unknown m3/2, tan, m0, sign()

Same LSP as in mSUGRA

  • Use the absence of signals to

constrain the parameter space

4D scan

ISAJET (no RC)

Roberto Chierici - DELPHI status report

rpv searches
RPV searches

Study signatures where SUSY particles decays do

not conserve either L (ijkLiLjEk) or B (ijkUiDjDk)

Production decay

LLEUDD

gauginos 2,4,6+Emis6q,8q,10q

sleptons 4,6+Emis 2+6q

stops 2q+4+Emis8q

No signal observed at LEP2

 set limits from the observed number of events

(in general dependent on the model parameters)

LLE UDD

40 GeV 38 GeV

103 GeV 102.5 GeV

87 GeV ~85 GeV

~90 GeV -

~87 GeV ~80 GeV

Roberto Chierici - DELPHI status report

spontaneous rpv

LEP2, 95% CL

PRELIMINARY

PRELIMINARY

Spontaneous RPV

S-RP breaking leads to the presence of a massless Goldstone boson J (LSP)

Only breaking in the third family considered (higher Yukawa couplings)

Look for Majoron production through

dominant BR

 two acoplanar  and missing E

72 candidates in 654.6 pb-1 LEP2 data, 72.32.5 expected

Roberto Chierici - DELPHI status report

slide19
LEP1

2-fermion

QCD

heavy flavours

 physics

spectroscopy

Roberto Chierici - DELPHI status report

lifetime
 lifetime

Topology Events (91-95) Method

3vs3 2101 ML fit to t=(v-BS)/csinTh

3vs1 15427 ML fit to t=(v-BS)/csinTh

1vs1 26036 (94-95) IP difference: d= csin 

miss distance: =d1+d2

Result

3p=(288.62.4stat 1.4syst) fs

(291.43.6stat 1.5syst) fs

(292.02.3stat 2.1syst) fs

(291.82.3stat 1.5syst) fs

36% corr.

LEP1 (1991-1995)

1p=(292.02.3stat 2.1syst) fs

Sources of systematics:

 parametrisation of resolution functions

 VD alignment corrections

 background description

Combining all results (with correlations):

=(290.91.4stat 1.0syst) fs

Roberto Chierici - DELPHI status report

testing lepton universality
Testing lepton universality

Using the DELPHI measurements of BRs():

g/g=1.00140.0053

g/ge=0.99960.0046

Under the assumption of e- universality:

BRe, =(17.8380.066stat0.068syst)%

g/ge,=1.00040.0041

 excellent agreement with e--

universality

PRELIMINARY

Roberto Chierici - DELPHI status report

helicity structure of fragmentation

s(mZ) = (0.1180.003)

Helicity structure of fragmentation

Aim: independent determination of s

NP power

corrections

perturbative QCD

ycut dependence

To account for hadronization corrections:

 MC correction (model dependent)

 Clustering of the data (hadronparton)

s(mZ)=(0.1080.001stat 0.012syst)

L/tot, renormalization scale, ycut

Using non corrected data (hadronization effects in):

s(mZ)=(0.1130.001stat 0.012syst)

A1=(0.140.06) GeV

Roberto Chierici - DELPHI status report

f 1 measurements
f1 measurements

Little known about P-wave mesons like 3P1 and 1P1

PRELIMINARY

Study 1++ meson production f1(1285), f1(1420) in:

Z  (KSK) + X0

1992-95

id. via RICH, TPC

m(KSK)<1.04 GeV

+-

m = (12744) MeV

w = (2912) MeV

background subtracted

Partial wave analysis:

m = (14264) MeV

w = (5114) MeV

Assuming the f1 BR into KSK the production rate

in hadronic decays of the Z is determined:

isot. back.

f1(1285)/(1295)

<n> = 0.1590.051 for the f1(1285)

<n> = 0.0510.011 for the f1(1420)

f1(1420)

1++ a0(980)

1++ K*(892)K

 the values of <n>/(2J+1) agree well with the fact

that the two meson constituents are of type uu/dd

1+- K*(892)K

Roberto Chierici - DELPHI status report

overview and perspectives
Overview and perspectives
  • It has been a year of intense activity for DELPHI:
    • Prepare at best our final processing of data and simulation
    • Finalise results and papers
      • precision LEP2+LEP1 measurements, constraints on SM
      • limits on new theories
  • DELPHI now and perspectives:
    • More than 60 (PhD) students working on DELPHI data
    • Still ~70 papers to be produced: a lot of physics output on

its way

 this is what we worked for since we started !!!

    • Activity will go on for the whole 2003...
  •  we want to have the best out of our data

Roberto Chierici - DELPHI status report

e beam from radiative events
Ebeam from radiative events

Determine s'/s from polar angles of fermions in

e+e-ff events with  lost in the beam pipe

s'/s = x = g(f1, f2) = mZ/s for radiative events

Fit the distribution of ECM = s1/2-s1/2(LEP)

Main systematic errors:

QED modelling 40 MeV

Bias correction 48 MeV

Aspect ratio 48 MeV

ECM = (+0.1510.175stat 0.079syst)GeV

PRELIMINARY

Roberto Chierici - DELPHI status report

slide26

PRELIMINARY

Observables (shape means)

s(mZ)

had. correctionpower corr.RGI+PCpure RGI

RGI

RGI describes data without need of power corrections for the hadronisation

 only 1 parameter (s)  better precision

Renormalisation Group Invariance

perturbation theory:

its prediction are free from

renormalisation schemes dependence

PCs in RGI seem redundant

Roberto Chierici - DELPHI status report

tgc sensitivity to dpa
TGC sensitivity to DPA

The expected effect of introducing DPA is to decrease limits on TGC by about

0.5-1stat.(study in qqqq channel)

PRELIMINARY

1. total cross-section variation

2. changes in angular distribution of Ws

qqqq only

Fit to data with WPHACT, no DPA

Fit to data with WPHACT, DPA

Fit to MC without DPA (i.e. the

expected shift)

Shifts DPA-noDPA for qq channels:

MC DT

g1Z -0.010-0.009

 -0.013-0.008

-0.067-0.057

 data consistent with expected

behaviour

Roberto Chierici - DELPHI status report

tgc evolution in time
TGC evolution in time

qq channels

All results are stable

during the years

TPC S6

PRELIMINARY

Roberto Chierici - DELPHI status report

doubly charged higgs

189-209 GeV

95% CL

Doubly charged Higgs

H appear in several extensions of the SM

PRELIMINARY

e+e- Z  H++H--  4 leptons

gauge bosons

other Higgs

the less constrained decay is with four s:

 look for four low multiplicity jets

events at LEP2

Data Expected bck. H++H--(PYTHIA)

1 0.9 40.5%

95% CL  limit @ 206.7 GeV

 use likelihood ratio to set limits on the

H++ production cross-section

m(HL ) > 100.4 GeV/c2 @95% CL

m(HR ) > 100.0 GeV/c2 @95% CL

1 candidate

Roberto Chierici - DELPHI status report

f 1 continued
f1 (continued)

Production rate per spin state

Measured differential cross-section

3P1

PRELIMINARY

PRELIMINARY

 compatible with the f1 resonances hypothesis

Roberto Chierici - DELPHI status report

dpa weights
DPA weights

To account for DPA corrections to CC03:

Correction as a weight from YFSWW

Khoze-Chapovsky Coulomb screening

Background events (ie non-CC03)

for which wDPA=1

Large

weights!

 net effect on total cross section larger

than 2%

Negative global weights due to uncorrected

interference. Corrected afterwards

Roberto Chierici - DELPHI status report