news from delphi analyses w. adam institute of high energy physics austrian academy of sciences on...
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News from DELPHI AnalysesNews from DELPHI Analyses
W. AdamInstitute of High Energy PhysicsAustrian Academy of Sciences
on behalf of the
DELPHI collaboration
LEP Jamboree, July 15th, 2003
LEP Jamboree, 15/7/03 News from DELPHI Analyses 2
StatusStatus
51 abstracts sent to EPS03 & LP03• Hadronic physics: 5• Hard QCD: 7• Heavy flavour physics: 7• Physics beyond the SM: 14• Test of the SM: 17• Detector and data handling: 1
14 papers published or accepted for publication since summer ‘02
27 drafts in review• 4 at journal• 7 at EP• 16 in internal review
Throughout the talk (unless stated otherwise):• results are preliminary• limits are at 95%CL
*After LEP shutdownThis story is purely fictional, and any resemblance to real persons and events is entirely coincidental!
© Dargaud
We are in the year 3AL*. CERN is entirely occupied by the LHC. Well, not entirely …A few small offices of indomitable LEP physicists still hold out against the invaders …
LEP Jamboree, 15/7/03 News from DELPHI Analyses 3
QCD & QCD & Physics Physics
Energy evolution ofevent shape distributions
Open b- and c-production
in collisions
s from event shapes
c formation in 2-photon collisions
Hadronic photon structure function
Inclusive J/ productionin 2-photon collisions
Inclusive f1 productionin Z decays
Search for b in 2-photon collisions
Masses, lifetimes and
production rates of ±
Electron structurefunction
b-quark mass effectsin the 4-jet rate
Colour reconnection in WW using particle flow and mW estimators
Correlations between particlesfrom different W bosons
mb at mZ
LEP Jamboree, 15/7/03 News from DELPHI Analyses 4
Open b and c Production in Open b and c Production in Collisions Collisions
Production mechanism:
Select b and c events using semi-leptonic decays:
• identify muons
• fit pt-spectrum to b,c and light quark components
651 events selected• uds normalisation fixed using fit to
hadron pt-spectra
• c normalisation fixed according to
LEP2 average (eeeeccX)
direct resolved
(eeeebbX) = 14.9 ± 3.3stat ± 3.4syst pb
LEP Jamboree, 15/7/03 News from DELPHI Analyses 5
Open b and c Production in Open b and c Production in … (2) … (2)
First time: use identified K to tag heavy quark flavour
• b like-sign K / (149 events)• c unlike-sign K / (171 events)
Fit c-fraction in unlike-sign sample:
Fit to like-sign sample consistent with previous result on b-production
DELPHI results confirm excess in observed b-production w.r.t. prediction
(eeeeccX) = 937 ± 191stat ± 206syst pb
LEP Jamboree, 15/7/03 News from DELPHI Analyses 6
Some other Some other Results Results
Inclusive J/ production in
collisions
J/ +- : selected 36 ± 7 events
c(2980) formation in collisions
Observed: c KSK, KKKK, KK
Not observed: c
Fits to mass spectrum, tot and c BRs radiative width from observed channels:
Recently CLEO, E835 and L3 have
measured lower values of .
(J/+X) = 45 ± 9stat±17syst pb
Estimated fraction from
resolved : 74 ± 22 %
pT2 = 13.9±2.0stat±1.4syst±2.7BR keV
LEP Jamboree, 15/7/03 News from DELPHI Analyses 8
EW MeasurementsEW Measurements
() cross section
WW cross sectionand anomalous QGCs
AbFB using inclusive
charge reconstruction
ZZ production
Single vector bosonproduction
-pair production
in collisions
WW production cross section and BRs
Mass and widthof the W boson
W polarisations
Charged TGCs
Ac,bFB using
prompt leptons
Precision EW measurementsat the Z resonance
Z* production
LEP Jamboree, 15/7/03 News from DELPHI Analyses 9
AAbbFBFB by Inclusive Charge Reconstruction by Inclusive Charge Reconstruction
observednumbers
asymmetry * relativesign up- / down-like
New method:• enhanced impact parameter tag
for event selection• neural networks for charge
(b / anti-b) tagging / hemisphere
AbFB to be extracted from 2 categories
of charge tagged events:
• single tag (NSfwd,N
Sbwd)
• unlike-sign double tag (NDfwd,N
Dbwd)
For each category:
Highest precision DELPHI AbFB analysis
• self calibration of key quantities• extensive study of systematics• uses also LEP1 off-peak and
LEP2 Z0 runs
Asymmetry calculated as function of• b-purity• polar angle of thrust axis• year of data taking
allows for• precise self-calibration• control of data MC• check for consistency
€
N fwd − Nbwd
N fwd + Nbwd
= AFB ⋅η ⋅p ⋅(2w −1)flavours
∑
LEP Jamboree, 15/7/03 News from DELPHI Analyses 10
AAbbFBFB by Inclusive Charge Reconstruction (2) by Inclusive Charge Reconstruction (2)
Enhanced b-tag uses• impact parameters & rapidities• decay vertex information
Efficiencies from data:
• b, c from # single / double tags
• correlations and uds from MC
Calibration in two steps• Careful tuning of resolutions in MC
for each year of data taking• Correction of b-tag values in MC
for c- and b-quarks, based on
measured (b-tag)
€
N fwd − Nbwd
N fwd + Nbwd
= AFB ⋅η ⋅p ⋅(2w −1)flavours
∑
fraction of events / flavour
Integrated event tag:data / MC after correction
c-efficiencies vs.hemisphere tag
(data, MC)
±1%
LEP Jamboree, 15/7/03 News from DELPHI Analyses 11
AAbbFBFB by Inclusive Charge Reconstruction (3) by Inclusive Charge Reconstruction (3)
€
N fwd − Nbwd
N fwd + Nbwd
= AFB ⋅η ⋅p ⋅(2w −1)flavours
∑
Inclusive charge tagging / hemisphere: Neural Network using
• estimated charge / B-hadron type from probability / track
• probability for each B-hadron type• jet charge & decay vertex charge
Self-calibration from data (number of double-tagged like / unlike-sign events)
• hemisphere correlation & background correction from MC
• c charge assignment using MC + calibration from fully reconstr. D*s
dilution factor (charge assignment probability) charge assignment
probability D* data/MC
MC: correlations vs. cut
LEP Jamboree, 15/7/03 News from DELPHI Analyses 12
AAbbFBFB by Inclusive Charge Reconstruction (4) by Inclusive Charge Reconstruction (4)
Result from simultaneous fit to AFB and b charge assignment probability
• inputs: “fwd” and “bwd” single and double tags + like-sign tags
Pole asymmetry
Main contributions to systematics:• hemisphere charge correlations• c and uds charge identification• QCD correction• detector resolution
√s (GeV) AFB stat. syst.
89.449 0.0637 ±0.0143 ±0.0017
92.231 0.0958 ±0.0032 ±0.0014
92.990 0.1041 ±0.0115 ±0.0024
€
AFB0,b = 0.0978 ± 0.0030stat ± 0.0014 syst
LEP Jamboree, 15/7/03 News from DELPHI Analyses 13
AAb,cb,cFBFB with prompt leptons & combination with prompt leptons & combination
Method
• using high pT & pL leptons (e,) to select semi-leptonic b- and c-decays
Inputs for b/c/background likelihoods
• pT & pL, b-tag and charge information (lepton and opposite hemisphere jet)
Asymmetries extracted by binned 2 fit to thrust and likelihoods. Pole values:
€
AFB0,b = 0.1021± 0.0052stat ± 0.0024 syst
AFB0,c = 0.0728 ± 0.0086stat ± 0.0063syst
Combination of DELPHI Ab,cFB measurements
€
AFB0,b = 0.0990 ± 0.0029
€
AFB0,c = 0.0706 ± 0.0068
(SM: 0.1036) (SM: 0.0740)
LEP Jamboree, 15/7/03 News from DELPHI Analyses 14
W-polarisation in eW-polarisation in e++ee--WW++WW--
Use decay angles as analyser:
Extract spin density matrix elements
using proj. operators W±’(*,*):
Assume CP-conservation:
• W-’ = W+
--’ • Im W-
’ = 0
Data sample:
• eqq’,qq’ selected by iterative discr. analysis for √s=189-208GeV
• 1880 events selected
Before extraction of SDM elements events were weighted to account for
• efficiency (typ. 70%)• purity (typ. 92%) and • migration (typ. angular resolution
0.05 in cosW, cos*; 80mrad in *)
as f(cosW,cos*,*)
need leptonic decays
€
for τ = ±1,0 : ρττ 'W −
(cosθW )∝
dσ (e+e− → W +lν )d cosθW d cosθ *dφ *
Λττ 'W −
∫ d cosθ *dφ *
*,* in W-restframe
LEP Jamboree, 15/7/03 News from DELPHI Analyses 15
W-polarisation in eW-polarisation in e++ee--WW++WW-- (2) (2)
SDM elements agree well withSM prediction (WPHACT):
00 differential production
cross section for WL:
averaged over e, and using both W- and W+
€
longitudinal
σ total
= (24.9 ± 3.3)%
expected : (24.0 ± 0.2)%
LEP Jamboree, 15/7/03 News from DELPHI Analyses 16
Single W productionSingle W production
We final states receive contributions from single W, W-pair and Zee.
Total cross section:
(assume lepton universality, =)
Need signal definition:• all t-channel diagrams, +
• W e: |cos(e1)| < 0.95,
|cos(e2)| > 0.95
• W l(l=e,): E(l) > 20 GeV
• W qq’ : M(qq’) > 45 GeV/c2
Ratio to SM / channel:
€
1.07+0.38
−0.35(stat)± 0.09(syst)
€
1.06+0.27
−0.25(stat)± 0.03(syst)
€
1.36 ± 0.18(stat)± 0.06(syst)
LEP Jamboree, 15/7/03 News from DELPHI Analyses 17
ZZ* Production* Production
Channels:
• eeqq, qq, qq
• 4 charged leptons• 4 quarks
“Matrix Element” signal definition
• |cosf|<0.98 4 fermions
• weight events by |MZ*|2/|Mall|
2
Final selection in bins in Mff-Mf’f’ plane
€
Zγ* = 0.137+0.029
−0.026(stat) ± 0.09(syst)pb
“LEP” signal definition: cuts on• production angle• di-fermion masses• compatibility with Z-mass
LEP Jamboree, 15/7/03 News from DELPHI Analyses 18
Method:• relation of densities for single-W and W-pairs (assume no correlation):
• measure for deviation: difference () or ratio (D) of left- / right-hand expression
• reference: MC predictions with LUBOEI within one (BEins) / two (BEfull) Ws
For background subtraction:• MC with BEC tuned on signal like Z0
Bose-Einstein Correlations in WW eventsBose-Einstein Correlations in WW events
€
Q = −( p1 − p2 )2
Fully hadronic WW events
Semi-leptonic WW events
€
p12WW (Q) = 2ρ p12
W + 2ρ p1W ρ p2
W = 2ρ p12W + 2ρ p12
Wmix
Mixed hadronic decays fromtwo semi-leptonic WW events:
• rotated / mirrored to balancemomentum
LEP Jamboree, 15/7/03 News from DELPHI Analyses 19
Bose-Einstein Correlations in WW … (2)Bose-Einstein Correlations in WW … (2)
Statistical aspects:• bins in correlated (multiple entries!)• described by covariance matrix• propagated to derived quantity D
Most pairs within one W:• use -factor & opening angle as
additional discriminants• reweight pairs acc. to purity
Fixing R to BEfull model:
€
=0.241± 0.075stat ± 0.038syst
D(Q): like-sign pairs
Fit D(Q)=N(1+e-RQ)(1+Q)
R(f
m)
Data
BEfull
LEP Jamboree, 15/7/03 News from DELPHI Analyses 20
MMW W - Contributions to Systematics- Contributions to Systematics
Detailed studies are underway to verify that no ALEPH-like cleaning is needed.
Summary (work in progress):• Electrons
Under control from the start of LEP2
No corrections• Soft energy flow
Complicated detailed studies.• Fragmentation
Large (well known) discrepancies
No problem for MW
• Detector effects
Small discrepancies for low energy clusters
Estimated impact order of 10MeV
Efforts concentrated around soft hadronic energy flow:
• charged energy flow
Discrepancies related to simulation of fragmentation - negligible impact
• neutral energy flow
Small differences seen, possibly due to detector effects
Final numbers and implementation of a possible correction expected in the nearest future.
Reminder: valid DELPHI number is
mW = 80.401 ±0.045stat ±0.034syst
± 0.029FSI ±0.017LEP GeV/c2
LEP Jamboree, 15/7/03 News from DELPHI Analyses 21
Searches: SUSY & ExoticaSearches: SUSY & Exotica
SUSY with light gravitinoand sleptons as NLSP
LSP gluino
Search for SUSY andinterpretation in MSSM
4th generation b’ quark
Anomaly mediatedSUSY breaking
SUSY withRp-violation
Single top via FCNC
+Emiss
SpontaneousRp-violation
Search for resonantsneutrino production
LEP Jamboree, 15/7/03 News from DELPHI Analyses 22
Search for 4Search for 4thth generation b’ quark generation b’ quark
Heavy 4th generation not excluded model with additional doublet (t’,b’)
If mb’>mZ and mb’<mt’,mt,mh :• dominant decays to cW and bZ• investigate 96<mb’<103 GeV/c2
Final states FCNC (∑BR≈81%):
• ZZ 2 l + 2 • ZZ 2 j + 2 • ZZ 4 j
Final states CC (∑BR≈90%):
• WW 2 j + l • WW 4 j
Limits on branching rations (using SM-
like for decay to heavy quarks)
b’
t’,t,c,u
W
W
Z,H,g,b’
b,s,d
LEP Jamboree, 15/7/03 News from DELPHI Analyses 23
Search for 4Search for 4thth generation b’ quark (2) generation b’ quark (2)
Interpretation within sequential model & extended CKM matrix• assume matrix real, ≈symmetric, ≈diagonal BRs = f(mb’,mt’,RCKM) with RCKM=|Vcb’/(Vtb’Vtb)|
• limits on CKM element ratio for two mt’-mb’ cases at limits of allowed range
lower limit from FCNC BRsupper limit from CC BRs
LEP Jamboree, 15/7/03 News from DELPHI Analyses 24
Searches: HiggsSearches: Higgs
Doubly charged Higgs
Neutral Higgs in MSSMbenchmark scenarios
Flavour independentneutral Higgs searches
Fermiophobic Higgs
Limits on mH and tan from a MSSM parameter scan
Charged Higgs ingeneral 2HDM
Neutral Higgs inextended models
Invisible Higgs
Neutral Higgs(SM and MSSM)
LEP Jamboree, 15/7/03 News from DELPHI Analyses 25
Extended MSSM neutral Higgs resultsExtended MSSM neutral Higgs results
Use all DELPHI results consistently Include contribution of H
Interpretation in 3 std. benchmarks:
• mhmax, no mixing, large
• using partial 2-loop calculations and mtop=174.3GeV/c2
Scan:
• basic grid: 1GeV/c2(mA)x0.1(tan)
• low mA: .02, .1, .25, .5, 1.5, 3GeV/c2
New LEP1 only limits• mh
max, no mixing:
Small unexcluded region at low mA and mh and tan ≈10:
• covered by limit on Znew.
mh > 44.6GeV/c2 (any tan)
mA > 44.4GeV/c2 (tan>1.7)
hZ
hA
cas
cad
es
LEP1
LEP Jamboree, 15/7/03 News from DELPHI Analyses 26
Extended MSSM neutral Higgs … (2)Extended MSSM neutral Higgs … (2)
mhmax no mixing
mh> 89.7 GeV/c2 > 92.0 GeV/c2
mA> 90.5 GeV/c2 > 93.0 GeV/c2
(tan > 0.4) (tan > 0.8)
Limit dependsstrongly on mtop
mhmax
no mixing
large
Exclusionincluding H
LEP Jamboree, 15/7/03 News from DELPHI Analyses 27
Flavour-Independent Search for h,AFlavour-Independent Search for h,A
Strategy:• design general search for
Higgs boson hadrons• reference samples: decays to gluons,
light & heavy quarks• for flavour-independent results take
most conservative assumption at each test point
Competing effects:
hZ m<40GeV/c2 m>40GeV/c2
4 jets “3-jet” likeprobabilistic
4-jet analysis
2 jet + Emiss“monojet”
likeIDA in 3
mass bins
2 jet+ee/ sequential
hA
“4 jets” High mass, mh≈mA
“3 jets”high m or low masses
“high thrust” both m < ≈40GeV/c2
gluons light quarks
efficiency mass resolution
arb. norm.
LEP Jamboree, 15/7/03 News from DELPHI Analyses 28
Flavour-independent Search for … (2)Flavour-independent Search for … (2)
Limits in terms of C2 = / (SM)
For individual flavours:• strange quarks:
mh > 108.0 GeV/c2 (110.6 expected)
• gluons:mh > 109.2 GeV/c2 (111.0 expected)
Limits in terms of C2
(=1 for max. allowed by EWSB)
LEP Jamboree, 15/7/03 News from DELPHI Analyses 29
Search for a fermiophobic HiggsSearch for a fermiophobic Higgs
General 2HDM• h can decouple from fermions• can decay to pairs of Higgs or gauge
bosons
• high BR in large parts of parameter space
• details depend on choice of potential describing H-H-couplings
Assuming SM + no couplings to ff:
hZ channel#events
(√s=183-209GeV)
qq 32 (27.2±0.4)
19 (19.5±1.1)
ll 3 (5.0±0.6)
mh > 104.1 GeV/c2 (expected: 104.6)
LEP Jamboree, 15/7/03 News from DELPHI Analyses 30
Search for a fermiophobic Higgs (2)Search for a fermiophobic Higgs (2)
hA production: searched for
• hA bb
• hA hhZ qq
excluded by hZ
excluded by hA
mh limit for
mA=115
mainly h , AhZ
mainly h , Abb
mainly h, Abb
LEP Jamboree, 15/7/03 News from DELPHI Analyses 31
ConclusionsConclusions
Physics output:• 14 publications since summer 2002• 27 drafts in pipeline• work in progress on ~ 25 other subjects
DELPHI is still a highly active collaboration!
Emphasis now on getting remaining analyses quickly to publication stage:
• many DELPHI members started second activity• tends to slow down reviewing process
You may expect many new final results at the next LEP jamboree !!!