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


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


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


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

eqeq

q

eqRR

eqLL

eqLR

eqRL

q

eqRR

eqLL

eqLL

eqRRNC

ZM

yMMMMPxq

yMMMMPxq

0

22222

22222

...)1(])()[(

...)1(])()[(


CI with the HERA-II NC data

Much better limits on: LL and RR


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


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


CC Inclusive Jet cross sections (HERA-II)

Jet Et softer, cross section smaller Inclusive CC cross section OK

Multijet more than in the MC ?


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


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


Radius dependence

R dependence well described by NLOhadr, if not perfect Hadronisation correction is large at small R


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


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


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


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


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


Charm through D* with HERA-II sample

NLO (still) describes the data

ZEUS


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)


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


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


D lifetime using the microvertex detector

Steady progress in understanding the MVD Alignment, tracking algorithm …


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/


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!


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?


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


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)


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)


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


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


Muon channel from ep: pTX distribution

Distribution after final selection, high purity W More spectacular events for e, if any

e+p ep


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


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”


Acceptance comparison in pTX

ZEUS smaller than H1 slightly because of the angular cuts Flat in pT

X


Summary

Finalising the HERA-I analysis Focus is moving to HERA-II

ZEUS is excited about large luminosityHoping for successful e+ running

ichep2006 results from zeus (+ one h1+zeus combined)

Documents

yamazakicc cross sections

disjet cross sections

dijet cross sections

rrichep2006 results

gevichep2006 results

talkichep2006 results

yamazakinc cross sectionsshown

shownquark radius hera