Post on 28-Dec-2015
A. Savoy-Navarro, Korea'08 1
The 3The 3rdrd generation as Probes for generation as Probes forNew Physics:The CDF caseNew Physics:The CDF case
Aurore Savoy-Navarro,UPMC-Paris/CNRS-IN2P3 France
ντ
A. Savoy-Navarro, Korea'08 2
Synopsis
• 3rd generation: WHY?
• How to detect/tag them?
• Probe for New Physics: the CDF case Some examples in:
B Physics
Top Physics
Higgs
BSM
A. Savoy-Navarro, Korea'08 3
WHY the 3rd generation?• The 3rd generation allows exploring important aspects
of Particle Physics: the
• Some key particles are made of heavy quarks (ex: the B mesons) • and/or decay into 3rd generation objects (ex: H0 but also Z0 →τ+τ-) • This decay channel may become even a dominant; ex:
τ-lepton becomes dominant in certain BSM cases (ex: also H0 if MSSM-like)• Third generation processes are backgrounds to NP (ex: top paire production…)
A. Savoy-Navarro, Korea'08 4
3rd generation objects detection has made impressive advances especially at CDF:
b-tagging & triggeringτ-tagging & triggering
but it’s quite challenging especially at hadron colliders
and challenging anyway: each member of the THIRD family has its own peculiarities
HOW TO DETECT THEM?
A. Savoy-Navarro, Korea'08 5
L00 + μvertex ISL: intermediate Si tracker Si vertex trigger: SVT
Central Outer gaseous Tracker (COT)
Plug calorimeter Part of the Muon detector
The detection of 3rd generation objects need ALL the components of a detector
A. Savoy-Navarro, Korea'08 6
Very important contribution of Tracker in CDF Trigger Architecture
L3: CPU farm Full event Reconstruction
Speed-optimized offline code
L1 pipeline
42 clock cycles
L1
L2
L2 buffer
4 events
DAQ buffers
L3 Farm
L1• 7.6 MHz Synchromous Pipeline• 5.5 μs Latency• 30 kHz accept rate
L2•Asynchromous 2 Stage Pipeline•20 μs Latency•1000 Hz accept rate
Mass Storage
(~100 Hz)
7.6 MHz Crossing rate
SVX read out after L1
SVT here
XFT here
XFT – Level 1
all trck pT>1.5 GeVσ(1/pT) = 1.7%/GeVσ(φ0) = 5 mrad96% efficiencySVT – Level 2
all trck pT>2 GeVσ(IP) = 35 μm, σ(1/Pt) = 0.3 % σ (φ0)=1 mrad
Ks
L3 plot 2001
D0
1.8 1.85 1.9 GeV/c2
800
400
0
Eve
nts
Two Track Trigger (TTT) IP>100 μm
D0
Upgrade:3D tracks
Upgrade:processing time
A. Savoy-Navarro, Korea'08 7
eXtremelyFastTracker
Good hit patterns are identified as segments, then segments are linked as tracks
XFT 3D upgrade:Add info from stereo layersFake rejection ~8
COT axial layers
COT stereo layers
Gaseous tracking chamber rebuilt from run I to run II to cope with luminosity x100 and for the first time a tracking LV1 trigger:
A. Savoy-Navarro, Korea'08 8
Upgrade SVT for luminosityUpgrade SVT for luminosity
p
event + underlying event + pile-up
p
Good Data@ higher Luminosity More Data @ lower Luminosity
Upgrade: Faster SVT components and:
32Kpatterns → 512Kpatterns new AM.
0 20 60 100 140 180 Luminosity (xE30)
original system
upgradedsystemFr
act
ion
of
ev.
Original SVT turned off above 90xE30
Upgraded SVT can run @high Lumi
At 3x1032: 5 pile ups
A. Savoy-Navarro, Korea'08 9
A dedicated new Higgs trigger & N.P. searchesA dedicated new Higgs trigger & N.P. searches
Ten orders of magnitude to fight against!! High luminosity gives largecalorimeter occupancy (pile up)that generates fake clusters/cluster merging (ex: red towersseen as one single cluster)
A. Savoy-Navarro, Korea'08 10
The upgraded Calorimeter The upgraded Calorimeter TriggerTrigger
courtesy of Simone Donati - 24x24 Calorimeter towers E(em),
E(had) sent to L2 CPU @full resolution (10
bit)- Jet, e/ clustering, MET computed
with offline-style algorithm (immune to
pileup).
- Use fixed cone algo: R=√(2 + 2)=0.7
L2Cal(4 Pulsar crates)
L2 CPU
10 bit E(em), E(had)
jet axis
Tr
The L1MET Upgrade
L2calPulsar
x6
L2CalPulsar
x6
L2CalPulsar
x6
PulsarMerger
PulsarMerger
PulsarMerger
PulsarMerger
PulsarMergerTrigger Tower
Energy(288 LVDS Cables)
Wedge Energy
L1METPulsar
Met Reconstructi
on to L1:Same L2
Resolution!
L2 PC performs clustering and Met calculation
Trigger Tower Energy
( 4 S-LINK cables)
Same Custom Hardware used to
calculate Met/SumEt for
L1
Commissioning Ongoing
Courtesy Laura Sartori
NEW!
A. Savoy-Navarro, Korea'08 12
Instantaneous Luminosity (x 1030 cm-2 s-1)
L2
Cro
ss S
ectio
n (
nb)
After L2Cal UpgradeBefore L2Cal Upgrade
Jet40L2 upgradesince Nov07
Courtesy Laura Sartori
Etmiss 25L1 commissioning
After L1 upgrade
Before L1 Upgrade
Effects of latestEffects of latesttrigger upgradestrigger upgrades on L1 and L2:on L1 and L2: 2 examples2 examples
This impacts also on the This impacts also on the
ττ- - triggerstriggers
A. Savoy-Navarro, Korea'08 13
τ+ → π+[π-π+] ντ (n π0)
BR=50%
BR=14%
An inner cone, shrinking with energy, 1 or 3 good tracks
τ IDENTIFICATION only possible in hadronic decay
Tagging and triggering based on:
A. Savoy-Navarro, Korea'08 14
Davis, LPNHE, PISA, Rutgers, TA&M installed in 2002
Primarily designed to trigger low Pt multileptons
Including τ’s
A. Savoy-Navarro, Korea'08 15
A. Savoy-Navarro, Korea'08 16
The Bs-world:
b
s
b
s
Bs0 Bs
0
MA
TTE
R
AN
TIM
ATTER
Bs observables: Δms = mH-mL≈2IM12I defines the mixing oscillation frequency
Different Lifetimes: ΔΓs=ΓL-ΓH ≈ 2 IΓ12I cos Φs
CPV: ΦsSM = arg(-M12/ Γ12) ≈ 4x10-3 rad (SM) Thus small value predicted by SM
Bs mesons = {bs} bound states
Transitions Matter ↔Antimatter via:NEW PHYSICS?
Bs sector is defined by 5 parameters:• Masses: mH, mL • Lifetimes: ΓH, Γ L (Γ=1/τ), • Phase: βs
The flavour eigenstates are linear combinations of mass and lifetimes eigenstates
A. Savoy-Navarro, Korea'08 17
ms measurementms = 17.77±0.10(stat)±0.07(syst) ps-1
Extracted parameters dominated by theoretical errors; Need more from LQCD
|Vts / Vtd|= 0.2060 ± 0.0007 (exp) +0.0081 (theo) -0.0060
CDF present focus S=H-L, (H+L)/2 and βs
1 fb-1
PR
L. 97, 242003 (2006)
(5.4 significance)
If NP occurs in mixing: Φs = ΦsSM + Φs
NP and 2βs = 2βsSM – Φs
NP standard approximation: Φs = -2βs
ALL in ONE process
βs = phase of b→ccs transition accounts for decay & mixing+decay= 2.20(SM prediction)
A. Savoy-Navarro, Korea'08 18
Flavour-tagging performance
Same tagging used successfully for mixing-frequency measurement
Opposite Side: looks at decay of the ‘other’ b-hadron in the event
Same Side: exploits the charge/species correlations with associated particles produced in hadronization of reconstructed B0
s meson
Output: decision (b-quark or antib-quark) and the probab. of being correct
OST efficiency 96 +/- 1% OST dilution: 11 +/- 2%
SST efficiency 50 +/- 1% SST dilution 27 +/- 4%
Total εD2 ~ 4%
A. Savoy-Navarro, Korea'08 19
Results
Assuming the SM, the probability of observing a fluctuation as large or larger than observed in data is 15% (1.5σ)
One dimensional: 0.16 < βs < 1.41 at 68% CL
PR
L100, 161802(2008)
A. Savoy-Navarro, Korea'08 20
Increased dataset still hints at larger than SM values!
Consistency with SM decreased 15% 7% (~1.8 σ)
(first sign of new Physics soon??)
0.28 < βs < 1.29 at 68% CL
www-cdf.fnal.gov/physics/new/bottom/080724.blessed-tagged_BsJPsiPhi_update_prelim/
3200 decays, S/B~2
ICHEP update
N.B. Analysis not yet optimized
A. Savoy-Navarro, Korea'08 21
FCNC decays forbidden at tree level, proceed through loops.FCNC decays forbidden at tree level, proceed through loops.
Higher order diagrams highly suppressed, allowing NP to manifest itself. Higher order diagrams highly suppressed, allowing NP to manifest itself.
B0d,s → μμ, B0
d,s → eμ, B0d,s → ee and D0 → μμ
LOOK for 2-body B, D rare decays at CDF:LOOK for 2-body B, D rare decays at CDF:
WHY:WHY:Ex: SM=> BR(Bs→μμ)~3.8x10-9 But BR enhanced by x10-103 by NP
A. Savoy-Navarro, Korea'08 22
B+ J/ K+
For B0d,s
B+ J/ K+
For B0d,s
B0d K+-, for
B0d,s ee, e
B0d K+-, for
B0d,s ee, e
D0
for D0 D0
for D0
Each search is relative to a normalization modeEach search is relative to a normalization mode
A. Savoy-Navarro, Korea'08 23
B ee, eμ signal after Lepton ID
mode CDF B.F. limit Previous best
B0s 4.7 (5.8) 9.4
B0d 1.5 (1.8) 3.9
B0s e 20 (26) 610
B0d e 6.4 (7.9) 9.2
B0s ee 28 (37) 5400
B0d ee 8.3 (10.6) 11.3
D0 43 (53) 13090%
(95
%)
BR
lim
its ×
108
World’s best lim
its
A. Savoy-Navarro, Korea'08 24
CDF has gained 2 orders of magnitude, now only about one order from SM
A. Savoy-Navarro, Korea'08 25
The TOP quark case
Interesting and not yet well studied case
(in progress) the top paire production
with the top decaying into τ (see next)
A. Savoy-Navarro, Korea'08 26
Search for top into τ’s : main motivations• Goal #1: First time 3 σ observation (not yet!)• Goal #2: Check BR(t→τνb) against Standard Model
– BR(WB) = 100% ? Or H+b ??
H-?
Good training camp for BSM searches
background of SUSY τ dominant decay at large tan β
Z→ττ + jets background• 1 τ→e or μ,1 τ→hadrons• Unlike the top signal:
– The 2 leptons are close– MEt points between them
OR opposite to them
• The τ ν’s energies can be reconstructed
• Veto event if it satisfies the former angular requirements and M(τ,τ) < 115 GeV
• This Z veto cuts 70% of Z→ττ and 8% of top signal
>115 GeV
CDF simulation
Other major background: QCD jets faking τ-jets
A. Savoy-Navarro, Korea'08 28
Results on 1.05 fb-1
PROCESS (1fb-1) (e, μ) + tau
Total Background 7.7 ± 1.7
SIGNAL (ttbar → l+τ) 6.4 ± 0.7
Total SM 14.1 ± 1.8
OBSERVATION 11
P-value: 8% Γ(t→τυq)/ΓSM(t→τυq) < 1.5 à 95% CL (2005 result : <5.2)
Impact of this result
Now starting study withpresentlyavailable data
A. Savoy-Navarro, Korea'08 29
Search for charged Higgs in top decaySearch for charged Higgs in top decay (cont’d)(cont’d)
Explore the possibility that t → H+b
with subsequent decay of H+ → c s Reconstruct event kinematics
Z! Top: interesting way to look for H± Z!
A. Savoy-Navarro, Korea'08 30
The many ways to produce a Higgs at CDFThe many ways to produce a Higgs at CDF
Hb,
b,_
mH<140GeV
mH>140GeV
HW(*),Z(*)
W,Z_
gg→H→bb dominates but huge QCD bkgd => close to IMPOSSIBLE
WH→lνbbZH→llbb
VH→ννbb,ν(l)bb
VH→qqbbH→ττ(+jets)
decay
A. Savoy-Navarro, Korea'08 31
Neutral SM Higgs into τ-leptons
Important to look at different decay mode (i.e. H→ττ, not
only H→ bb).
Analysis optimized for SM Higgs, but sensitive to
non SM Higgs.
MSSM predicts a much higher H-rate for large tanβ
in gg fusion, especially in τ-decay.
A. Savoy-Navarro, Korea'08 32
Search for a SUSY Higgs into 2 Search for a SUSY Higgs into 2 ττ’s’s
σ(MSSM) ~ σ(SM) x tan2β ττ signal: lower background τ-BR increases with tanβ
A. Savoy-Navarro, Korea'08 33
The many ways to search for Higgs at CDF The many ways to search for Higgs at CDF the high mass case: H→WW→lthe high mass case: H→WW→lννllνν
The physics backgrounds Analyse strategy:
0 jet events
1 jet events
≥ 2 jet events
WW/WZ
W+Jets/γ
WW/WZ
And: Drell-Yan, ttbar, single top, Multijetsall these processes are well measured
A. Savoy-Navarro, Korea'08 34
0-jet evt 1-jet evt
2+ jet evt
NN with different inputs are trained for each case Anti-b tagging is added in the ≥ 2 jets case, in order to get rid of the ttbar backgroundThe results obtained for each of these 3 cases arethen combined,
and the CDF result isand the CDF result is
A. Savoy-Navarro, Korea'08 35
CDF result on 3 fbCDF result on 3 fb-1-1 of data of data
σσ x BR (H→WW*) expected limit 1.66 times SM x BR (H→WW*) expected limit 1.66 times SM
for a Higgs mass of 165 GeV; Observed 1.63for a Higgs mass of 165 GeV; Observed 1.63
CDF & D0 combined exclude m(H0) =170 GeV at 95% CL CDF & D0 combined exclude m(H0) =170 GeV at 95% CL
(See Rob Roser’s talk)
A. Savoy-Navarro, Korea'08 36
A minimally supersymmetric world ? proposes a new symmetry
Fermions ↔ Bosons
A. Savoy-Navarro, Korea'08 37
Ex 2: SUSY Trileptons searchusing lepton+track trigger
CDF selection:
Backgrounds
Dominant if Large tan β
A. Savoy-Navarro, Korea'08 38Courtesy Sourabh Dube
A. Savoy-Navarro, Korea'08 39
100
Courtesy Sourabh Dube
A. Savoy-Navarro, Korea'08 40
100
Courtesy Sourabh Dube
A. Savoy-Navarro, Korea'08 41
Ex 2:Searches for sbottom quarkEx 2:Searches for sbottom quark • If large tan , light sbottom is expected
• Dedicated searches for b production (B.R.bb100%)
direct pair production or b from gluino decays
gg ~ 10 bb , consider region
and mass(gluino) > mass(sbottom)
Final state:
ET + 4 b-jets
~~
b
b
b~
b~g~g~
g~g~0~0~
0~0~
b
b
~
~~ ~~0~
1~~, mmmm
bt
Main background processes:- QCD-multijets- light-flavor jets tagging (“mistag”)- Top production, W/Z+jets, diboson
Predictions tested in Control Regions
B-tag algos
A. Savoy-Navarro, Korea'08 42
Exclusion limitsExclusion limitsExcluded above 0.1 pb
(M(g) ~ 350 GeV/c2)~Translated into limits on the gluino-sbottom mass
plane
Sbottom masses up to 300 GeV/c2 are excluded for M(g)<340 Gev/c2~
A. Savoy-Navarro, Korea'08 43
Ex 3: Search for RpV-SUSY Top Quarks decaying to a b-quark and a τ-lepton (all 3 in one)
Based on (only) 322 pb-1 of data collected by lepton+track triggers
Look for channels with one τ decaying leptonically and the other hadronically.
Expected 2.26+0.46-0.22 events; observed 2.
A. Savoy-Navarro, Korea'08 44
stop→τ b event
Upper limit on σ(production)
If Br(stop-->τ b) = 100%, Lower limit M(stop)i=155 GeV/c2 (assuming NLO cross-section for stop pair production). If theoretical uncertainties due toPDF's + factorisation scale taken into account, imit =151 GeV/c2
A. Savoy-Navarro, Korea'08 45
Concluding remarks: perspectives• CDF has been instrumental in developing the tools (hard-
software) to exploit the potential of the 3rd generation to tackle New Physics
• This is a particularly “high-tech Physics”: Theory, detector, analysis points of view
• Identifying these tricky objects (3rd family not and easy family…) in real time is a preriquisit especially in hadron colliders
• The future is in an heavy flavored world: LHC experiments must address very soon this issue and upgrade their detecting capacity consequently
• In this aspect also CDF is a precursor and pioneer: breakthroughs may still be expected