ICHEP2006 results from ZEUS (+ one H1+ZEUS combined)
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Transcript of ICHEP2006 results from ZEUS (+ one H1+ZEUS combined)
24 July 2006 ICHEP2006 results from ZEUS / Y. Yamazaki 1
ICHEP2006 results from ZEUS(+ one H1+ZEUS combined)
DESY seminar“Sneak Preview of ICHEP06 Contribution”
24 July 2006
Yuji Yamazaki (KEK)
On behalf of the ZEUS and also H1 collaborations
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ICHEP preliminary from ZEUS
High-Q2 / BSM searchCharged current with polarised e- beamNeutral current with polarised e- beamCombined EW+QCD fit on above twoContact interactionSearch for stop productionSearch for Gaugino/GravitinoMulti-lepton production (e and ) Search for high-pT leptons
Heavy flavoursCharm cross section by D mesons and fr
agmentation fraction in DISD* cross sections from HERA-II dataBeauty from dimuon (NLO comparison)Beauty in DIS (NLO comparison) D lifetime measurement with the MVDHelicity measurement in inelastic J/
QCD through hadronic final stateBose-Einstein correlation for K0 and K
Heavy stable particle productionForward jet productionMultijet production at low-x in DIS3- and 4-jets in photoproductionPrompt + jet in photoproductionLRG between jets in photoproductionK0 and production in p and DISInclusive and dijet cross sections in DISJet radius dependence
of the inclusive jets in DISJet cross sections in charged current, HE
RA-II Diffraction
Energy and pT distribution of the leading neutrons in DIS and photoproduction
Diffractive D* in p (NLO comparison)
List of subjects made preliminary after EPS2005Red ones are new for ICHEP – covered in this talk
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NC cross sections(shown in DIS2006)
Very good agreement No hint of new physics
(unfortunatelly …) You saw combined H1+ZEUS
cross sections earlier today
EW parameters extracted in DIS06
Now contact interaction limit
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Contact interactions (CI)
Generic parameterisation for new physics at much higher energy than s
Effective Lagrangian for vector CI:
NC with polarisation: sensitive to LL or RR
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ZM
yMMMMPxq
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CI with the HERA-II NC data
Much better limits on: LL and RR
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CI limits interpreted by models
Cut-off scale Ms on large
extra dimension~ Order of the Planck scale in the extra dimension world
Leptoquarks (not shown) Quark radius
HERA-I limit:(+0.85, -1.06)10-16 cmNow:(+0.67, -0.81)10-16 cm
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CC cross sections (shown in DIS2006)
Good agreement withNLO QCD theories
How about jets?Naïvely as good as NC The EW and QCD
vertex factorises High statistics e LH
sample
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CC Inclusive Jet cross sections (HERA-II)
Jet Et softer, cross section smaller Inclusive CC cross section OK
Multijet more than in the MC ?
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Dijets in NC
: reconstructed parton momentum
Full HERA-I statistics The renormalisation
scale uncertaintyis small at large Sensitivity to gluons
Different linesindicate choice ofrenormalisation scale
Breit frame, ET > 12 / 8 GeV
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Jet-radius dependence of the NC jet cross sections
The jet studies at HERA (e.g. the previous slide)uses R = 1 in the longitudinal invariant kT-algorithm
Better to use smaller cone radius for reconstructing decay jets from heavy states (t, Z0, W, Higgs, SUSY ….) Even R = 0.3 is common
Does the NLO theory correct for smaller radius?Important input to the LHC physics
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Radius dependence
R dependence well described by NLOhadr, if not perfect Hadronisation correction is large at small R
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Prompt photon + jet in photoproduction
Similar to dijet process Constrain PDFs (p, ) Smaller hadronisation
correction Statistics small
Measurement at low ETGood agreement with various theorieswith ET > 7 GeV and ETjet > 6 GeV cut
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If the photon has lower energy than the jet …
ET > 5 GeV, ETjet > 6 GeVEnhancing higher-order diagrams near threshold
kT-factorisation calculation seems better, but why? To be understood on the
theory side
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Multijet production at low-x in DIS
Aim: studying angular/kT disordering in multijets e.g. classic question on
DGLAP vs BFKL Trial 1: azymuthal angle
between two leading jets Idea came from H1 Never less than 120°in the di
jet plane for 3-jet events HCM frame: < 120°if:
Dijet plane “tilted” Higher ET jet outside the
rapidity range Sensitive to high-ET forward jet
O(s3) calculation
[NLO to 3-jet] reproduces the data
p
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ET between leading two jets
Trial 2 Large imbalance, if there is a
jet with ET higher than the 2nd jet outside range Angular disordering or FSR
by NLO not perfect ?
Large excess at large ET over the NLONB: LO+PS MC (LEPTO) reproduces the data wellangular ordered angular disordered
p
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QCD studies through HFL production
Charm / beauty through the BGF diagram: Test QCD and production mechanism under
multi-scale: mQ and Q2 and/or ET
If this is understood: sensitivity to the gluons in the proton
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Charm through D* with HERA-II sample
NLO (still) describes the data
ZEUS
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F2cc(x, Q2) from non-D* charm mesons
(HERA-I data)
The stat+syst error from D0 is comparable to D*Approaching close to the uncertainty from the PDF
with ZEUS-S fit(to inclusiveDIS data only)
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Beauty in p: pT dependence
b-quark level pT dependence Uncertainty in the
extrapolation is not fully estimated for some of the points.
New points fromZEUS at low-pT
D* and tag
High-pT is OKLow-pT shows slight excesssomething to do with the threshold behaviour?
Analysis from the HERA-II big luminosity awaited This plot is in case the combinedplot above is not approved by H1
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Beauty in DIS (HERA-II) with NLO
Update from previous HERA-I analysis: Jet in the lab frame Muons with wider
kinematic range (e.g. pT
)
Excess everywhere over NLO
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D lifetime using the microvertex detector
Steady progress in understanding the MVD Alignment, tracking algorithm …
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Helicity in inelastic J/ in photoproduction
Colour singlet (CS) only or need colour octet (CO+CS): debate between Tevatron and HERA Tevatron cross section: need CO HERA: consistent with CS only
HERA cross section is systematics limitedhelicity of J/ may tell something more Gluon radiation flips the helicity of J/
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Inelastic J/: helicity parameters
: transverse +1, longitudinal: -1
no big difference between CS and CO
: non-zero value shows helicity (double-)flip
Data prefers CS+CO?
big sample!
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Diffractive D* in PHP: NLO comparison Large cross section
difference between HERA and Tevatron (~1/3-1/10) “factorisation breaking” Attributed to soft rescatteri
ng (a.k.a. gap survival probability)
HERA resolved-p jet cross section is expected to be suppressed Measurement: both direct
and resolved are somewhat suppressed
How is p D* ?
NLO reproduces the data
No sign of factorisation breaking at HERA?
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Gravitino search
In the GMSB (gauge-mediated Supersymmetry breaking models): 1
0 decays to G and G is the LSP
Photon + Missing pT
Search onplane
~ ~
~
) ,( 10
~~xe mm
L
F: intrinsic SUSY breaking scaleN: number of the messenger fields: overall sparticle mass scaleM: mass of the messenger particle
Higgs sector mixingparameter
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Multi-lepton production
SM : Bethe-Heitler processesep el+lp, el+lX
H1 sees excess at high mass Today: ZEUS HERA-II analysis
(up to 2005) on ee/eee and (e)
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Multi-lepton (1) ee and eee
No excess seen in ZEUS at M > 100 GeV e+: 1 / 0.8 (ee), 0 / 0.4 (eee) e: 0 / 0.7 (ee), 0 / 0.4 (eee)
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Multi-lepton (2) di-tau
Searched through e pair Branching ratio 6.19 %
3 evts / 2.0 0.8 expected Background from
ep ep : < 0.3 events
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High-pT leptons: update on muon channel
Muon study with the cuts similar to H1 04/05 e shown in PRC May Now 98-05 e/e+ complete
NB: H1 ~100pb1 more with 94-97 and 06 data
No excess in ZEUS, both in e and e+
new
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Muon channel from ep: pTX distribution
Distribution after final selection, high purity W More spectacular events for e, if any
e+p ep
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Numbers from H1 and ZEUS, e and
PTX > 25 GeV
obs./exp. (SM)e channel channel e and combined
H1 electrons
98-06, 184pb-13 / 3.8 0 / 3.1 3 / 6.9 1.0
H1 positrons
94-04 158pb-19 / 2.3 6 / 2.3 15 / 4.6 0.8
ZEUS electrons
98-05 143pb-13 / 2.9 2 / 1.6 good agreement with SM
ZEUS positrons
99-04 106pb-11 / 1.5 1 / 1.5 good agreement with SM
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Acceptance comparison btw. H1 and ZEUS
ZEUS and H1 efficiency similar in the overlapped region Most of the H1 events are in the ZEUS acceptance
ZEUS will try extending the acceptance to the smaller angle (forward)
… an outcome from the “HERA exotic combined working group”
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Acceptance comparison in pTX
ZEUS smaller than H1 slightly because of the angular cuts Flat in pT
X
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Summary
Finalising the HERA-I analysis Focus is moving to HERA-II
ZEUS is excited about large luminosityHoping for successful e+ running