1

Emmanuelle PEREZDESY & CEA-Saclay

DIS ’06, Tsukuba 20 April 2006

14th International Workshop on Deep Inelastic Scattering

Recent Results from the H1 Experiment

- High Q2 DIS: inclusive measurementssearches for new physics, jets

- Hadronic Final State in low Q2 NC DIS

- Diffraction: vector mesonsinclusive diffractionfinal states

- Rare processes

E. Perez DIS’ 06, 20 / 04 / 062

H1 datasets

Polarisedleptons

03-04

05

98-99

99-00

94-97

HERA I : ~ 130 pb-1

- mainly e+ p data - several analyses getting finalised on HERA I data

HERA II (since 2003) :

- 50 pb-1 of e+p

- 100 pb-1 of e-p - polarised leptons, P typically 30 -40 % - analysed so far: what benefits from polar, stat, and new capabilities of the H1 detector

Analyses presented here :

up to 280 pb-1

E. Perez DIS’ 06, 20 / 04 / 063

Charged Current DIS

CC(e,SM) ~ (1 Pe)

e- p

21 pb-1

30 pb-1

69 pb-1

27 pb-1

e+ p

HERA I

Extrapolations to Pe = 1 consistent with no WR

• e+ p : first publication on HERA II data (PLB 634 (2006) 173)

• e- p : prelim. measurements with the full available 05 stat.

(syst.) typically 4%, (stat.) from 2% to 8%

First H1 diff. CC x-section measurements on HERA II data : agreement with H1PDF2000

E. Perez DIS’ 06, 20 / 04 / 064

Polarised Neutral Current DIS

Expected polarisation dependence confirmed although with

limited precision.

d/dQ2 measured for NC DIS in HERA II polarised data.

At high Q2 ( Z interference ) :

RH / LH > 1 for e+ p,

RH / LH < 1 for e- p

e+ p RH / LH

e- p RH / LH

E. Perez DIS’ 06, 20 / 04 / 065

Measurement of xF3

Correct for polar. effect :

(e-) - (e+) gives access tothe non-singlet SF xF3 ~ x ( q – q )

~

-

Combine HERA I

(15 pb-1 e-, 100 pb-1 e+)with HERA II

(120 pb-1 e-, 50 pb-1 e+) stat. errors reduced by 20-30 %

Neglect pure Z contribution(small) and correct for propagator terms little

dependence on Q2

Test the x dependence of valence quarks.

~ 2uv + dv

~

(if s = s )-

E. Perez DIS’ 06, 20 / 04 / 066

Jets in high Q2 NC DIS: constraints on *

e

q

*

W

, e

, Z, W

q

- Excited fermions: signature of a new scale of matter- Can be singly produced in DIS- Excited neutrinos would be produced much more

copiously in e- p than in e+ p

All decays analysed (with W/Z jets)For large M(*) : * eW dominates

Analysis of 2005 e- data (114 pb-1)

High Q2 NC DIS, several jets

H1 PreliminaryMost stringent

constraints so far !

f/

decay Z eW

SM backgroun

d

Radiative

CC

CC multijet

s

NC multijets

No resonancein any of the3 channels

For f/ = 1 /MM > 188 GeV

E. Perez DIS’ 06, 20 / 04 / 067

Jets in High Q2 NC DIS : S

measurementsInclusive jets in Breit frame

Q2 > 150 GeV2

Largestatistics !

Fit S(MZ) in each (Q2, ET) bin

using NLO calculations.

S(MZ) = 0.1197 0.0016 (exp.) +0.0046

-0.0048(th.)

Combined fit leads to:

but large theo. error (scale uncertainties)

Exp. error ~ 1.3 %Reduced by a factor of 2 w.r.t. 2001 analysis (reduced had. scale uncertainty)

61 pb-1

E. Perez 8

HFS in high Q2 DIS: fragmentation

For tracks in the current region ofthe Breit frame: xp = p / (Q/2)

xp1/N

events

dn

/dxp

Q increasing

Increased stat. (60k evts)

High Q2, <Q> up to ELEP

Full xp range

45 pb-1 (2000)

Clear scalingviolationsobserved

Well described by RAPGAP (frag.model tuned to ee data)

Good agreement with ee data (a bitsofter ?) quark fragmentation universality

Comparison with NLO calculations show sensitivity to frag. functions.

Norm. charged particle momentum distrib.

E. Perez DIS’ 06, 20 / 04 / 069

0 / separation in low Q2 DISMeasurement of prompt photon in DIS:

HERA I data, 71 pb-1

Q2 > 4 GeV2, ET > 3 GeV, -1.2 < < 1.8

isolated with z = E / Ejet > 0.9Variables based on the shower shape combined into a likelihood discriminator

Extended range ( x 10) w.r.t. previous HERA meas.

MC describes the rate of isolated 0 in the HFS !

e * e dominates

-1.2 < < -0.6 0.2 < < 0.9q * q dominates

Cross sections welldescribed by recent

O(3) QED calculation

First H1 measurementof prompt in DIS

e * e and

q * q

E. Perez DIS’ 06, 20 / 04 / 0610

Jets in low Q2 DIS : QCD at low x

99-00 data, 44 pb-1

hep-ex/0508055

Study jets in low x DIS, where DGLAP might be unsufficient to describe g radiation

• forward jets : theory & models

too low at low xBj

• search for gluon radiation

unordered in kT in 3-jet events

3 jets with PT* > 4 GeV

10-4 < x < 10-2, 5 < Q2 < 80 GeV2

~ 40 000 events

Comparison with MC programs: - DGLAP based MC : normalisation too low (60%) shapes are not described

- Color Dipole Model (unordered kT): OK

Only MC with kT-unordered gluon radiation

describes the data.

E. Perez DIS’ 06, 20 / 04 / 0611

3-Jets in low Q2 DIS : QCD at low x

Comparison with NLO O(S3):

NLO < data at lowest x, largest Look separately in 2 subsamples: - 1 forward + 2 central jets - 2 forward + 1 central jets

Huge improvement LO NLO :

O(S3) includes the “first

kT-unordered” radiation

Strong hints that, in this region of phase space, the effect of

kT-unordered gluon radiations

is important.

Discrepancy mainly in the “2 forward jets” sample.

E. Perez DIS’ 06, 20 / 04 / 0612

Further BFKL insights: VM at large t

hep-ex/0603038

2g

BFKL

t

At large t : photoproduction of VM described in pQCD by : - LO : exchange of two gluons - beyond LO : exchange of a gluon ladder

Different predictions for the t-dependence andfor the helicity structure of the interaction.

Analysis of , 20 pb-1 (2000)e detected in low-angle electrontagger (trigger…)

- t-dependence- spin density matrix elements

better described by gluon ladderexchange.

Probability for T L

interference

But no model describes all thefeatures of the data.

2g

BFKL

E. Perez DIS’ 06, 20 / 04 / 0613

photoproduction at low tVM production with no hard scale expected to be described by Regge phenom.

HERA II : Fast Track Trigger trigger on tracks

down to PT of 100 MeV New measurement on 2005 data :

- Extraction within a single experiment- No use of low W data (exchange of other trajectories)

~ 300 K events !

H1 2005

d/dt (W) for elastic and

p-dissociation

0 = 1.106 0.003 ’ = 0.156 0.027

+ 0.005- 0.014+ 0.019- 0.062

Assuming (t) = 0 + ’ t :

OK with DL

’ much lower than the slope of the soft Pom !!!

???

Old H1 meas. (1994 data): ~ 300 events (tagged p)

E. Perez DIS’ 06, 20 / 04 / 0614

The Pomeron Trajectory in diffractive DIS

Select diffractive DIS events by taggingthe leading proton (carrying a fraction

1-xPom of incoming p momentum) in our

Forward Proton Spectrometer (FPS) Allows t measurement Study d/dt ~ eBt in bins of xPom

Regge approach: B = B0 – 2 ’ ln(xPom)

Increased Reggeon contrib.

’ = 0.06 +0.19 -0.06 GeV-2

Small shrinkage favoured

Factorisation of the

t-dependence

from (Q2, x)

28 pb-1 (99-00)~ 3000 events

pxPom

( = x / xPom)

Final results

Low xPom : B ~ 6 GeV-2

P(0) also extracted

from the xPom

dependence

E. Perez DIS’ 06, 20 / 04 / 0615

Diffractive DIS with Large Rapidity Gaps

Our final results

• Large kinematic domain covered• Precise measurements : syst. typically 5%, normalisation ~ 6%, stat. 5 – 20%

Q2 range Luminosity

3 < Q2 < 13.5 GeV2 2 pb-1 (1997 “minimum bias”)

13.5 < Q2 < 105

GeV2

11 pb-1 (1997)

133 < Q2 < 1600

GeV2

62 pb-1 (1999-2000)

LRG (max method)

Comparison with FPS data :

LRG/FPS = 1.23 0.16

xPom = 0.003

=0.017 (x = 5 10-5 )

=0.67 (x = 0.002)

H1LRG

Amount of p-dissin LRG meas. shows no kinem. dependenceon Q2, xPom,

E. Perez DIS’ 06, 20 / 04 / 0616

Diffractive DIS with Large Rapidity Gaps

xPom = 0.003

xPom = 0.03

Reggeon contribution important

at high xPom and low

Diffractive cross-section remains sizeable up to largest values.

dependence: driven by quark diff. PDFs

E. Perez DIS’ 06, 20 / 04 / 0617

QCD analysis of LRG : DPDFs

IP + Reggeon contributions

MRS ansatz: A zB (1-z)C

A,B and C necessary for (z)Gluon poorly constrained :

Similarly good fits obtained withAg and Cg, and with Ag only (Fit B)

Gluon carries ~ 70% of the momentum of the colorless exchange

2 / ndf = 158 / 183

Fitted Reggeon normalisation in very good agreement with that obtained in the FPS data.

No kinem. dependence of P(0)

observed.

(“Proton vertex factorisation” assumed)

E. Perez DIS’ 06, 20 / 04 / 0618

Previous analysis

Factorisation in diff. DIS : jetsDijet events with a LRG 2700 evts ( x 6 w.r.t. previous H1 analysis :

50 pb-1 (99-00 data), extended kinematic range )Overall good agreement with NLO predictions.

Confirmation thatfactorisation holds.

Preferencefor “Fit B”

Log10(xPom)

Fit B Differences showup in variablesmost sensitiveto the gluondensity at high z

FitFit B

xPom

E. Perez DIS’ 06, 20 / 04 / 0619

Using jets to better constrain DPDFs

Combined fit of F2D

and dijet data :

2/ndf (total) = 196 / 217

2/ndf (dijets) = 27 / 36

2/ndf (F2D) = 169 / 190

Combined fit ~ close to Fit B; dijets

provideimportant

constraints on high z

gluon !

Both datasets well described by the combined fit.

E. Perez DIS’ 06, 20 / 04 / 0620

Factorisation in diff. DIS: charm

• New measurement: exploit the long lifetime of charmed hadrons : Use track impact parameters meas. with the SiDet; inclusive method no large extrapolations

S = / ()

50 pb-1 (99-00)• Use D* to identify c quarks prel. meas.

Good agreement with the D* x-sections(extrapolation factor ~ 2.5)

Good agreement with NLO QCD using the

DPDFs obtained from F2D

(complementary to jets since lower PT lower z)Charm production accounts to ~ 20% of the diff. x-section (cf. inclusive case)

measurement of F2Dcc in bins in (xPom, Q2, )

Q2 = 35 GeV2

xPom = 0.018

Cf H1,EPJ. C45 (2006) 23

E. Perez DIS’ 06, 20 / 04 / 0621

F2D on 99-04 data

- 97 : 10 pb-1

- 99-00 : 35 pb-1

- 2004 : 35 pb-1 (fwd det. a bit )

Medium Q2 : 12 < Q2 < 90 GeV2

99-04: Low Q2 & large not yet

Measurements confirm 97 datawith reduced stat. errors

Q2

E. Perez DIS’ 06, 20 / 04 / 0622

Extraction of the diff. component: max vs

MX

Result of subtraction

Limited lever-arm

due to acceptance: MX reco’ed with

LAr calorimeter ( < 3.4)

Comparison H1 / ZEUS : methods used

Try the “MX” method on 99-00 data

- ZEUS: good E meas. up to = 5- in contrast, H1 has good taggers up to 7.5

Non-diffexp. fall-off

M X in

crea

ses

No bias found with the MX method in

the (limited) range where H1 canapply it.

E. Perez DIS’ 06, 20 / 04 / 0623

Rare processes at HERA : +- production

hep-ex/0604022

Small Q2

Often notdetected

Maximal S/B when restricting toelastic production i.e. DIS & pbackgrounds mainly from diffractive processes

Final states: e, ejet, jet, jetjet

Use of neural networks to separate -jets from hadronic jets

In kinem. range 20o < < 160o, PT > 2 GeV:

= 13.6 4.4 3.7 pb

First observation of pair production at HERA

signal

Bckgd from diff.

dijets at zpom 1

108 pb-1 (HERA I data) :

Nobs = 30 (7 e, 2 ejet, 10 jet, 11 jetjet )

Nexp = 27.1 4.1 (60 % from )

E. Perez DIS’ 06, 20 / 04 / 0624

Search for W

Search for W in HERA-I data completed

PTX

(W prod) 1 pb

Effi. x Acc. ~ 8% :- 1-prong had. decays only (~ 49%)- limited range

Combining with prelim. results on HERA-II data :

H1 prelim.,278 pb-1

H1 prelim94-05

Observed SM expectation

Signal

All PTX 25 24.3 4.6 2.0 0.4

PTX > 25

GeV

3 0.74 0.15 0.43 0.09

A few events observed at PTX > 25 GeV in

HERA II data – but limited statistics…

Isolated + PT,miss

hep-ex/0604022

25

W Production (e & )

Positrons

W e, : isolated e, + PT,miss + had. System (PTX)

Electrons

PTX > 25 GeV e channel channel

Combined e &

Electrons, 98-05121 pb-1

2 / 2.4 0.5

0 / 2.0 0.3

2 / 4.4 0.7

Positrons, 94-04 158 pb-1

9 / 2.3 0.4

6 / 2.3 0.4

15 / 4.6 0.8

Effi. x Acc. ~ 30%Wide range

High W purity(87% at high

PTX)

excess not seen in e- p !

In e+ p : 3.4 effect…Our best chance for adiscovery !

E. Perez DIS’ 06, 20 / 04 / 0626

Multilepton events at HERAEvents with 2 leptons in final state. Mainly produced via

H1 data 94-00 : excess of 2e+3e events at high M12 = mass of two highest PT e

Analysis extended to include 03-05 data

Extended to other 2l & 3l topologies :Now ee, , e, eee, e are considered

• no new 2e / 3e evt at M12 > 100 GeV

(but one high mass 3e event …)• one e evt at M > 100 GeV, one at Me > 100 GeV

H1 Prelim., HERA I+II

275 pb-1

2l + 3l Altogether, at PT > 100 GeV :

Nobs = 4, Nexp = 1.1 0.2

The H1 evts are not consistent with e H++ (e) ee(e)

E. Perez

Cross-section when both leptons are central,

PT1 > 10 GeV, PT2 > 5 GeV : < 1 pb

hep-ex/0604027

All high mass evts in e+p …

Significant constraints set on H++ coupling to e- and to e-

E. Perez DIS’ 06, 20 / 04 / 0627

Concluding remarks

Diffraction: finalisation of analysis using the Forward Proton Spectrometer and of inclusive Large Rapidity Gap analysis

Combined fit F2D + dijet data Further tests of factorisation (also D* in photoproduction)

• First combinations of HERA I & HERA II : xF3 measurement, searches

• New preliminary results on HERA II data: *, F2D, with Fast Track Trigger, also DVCS measurement

• Finalisation of analyses on HERA I data:

Also on hadronic final states and heavy flavor physics

We are entering a new phase of analyses aiming to the highest precision.

28

H1 talks at DIS’06Andrei Nikiforov   Neutral current studies at HERA II   Jacek Turnau   Measurement of Event Shape Variables in DIS at HERA   Katja Krueger   Photoproduction of di-jets with High Transverse Momenta at HERA   Steve Maxfield   Inclusive Jet Production in DIS at high Q2 at HERA   Dima Ozerov Search for a Narrow Baryonic Resonance Decaying to K0_s p(pbar)   Carsten Schmitz   Prompt Photons in DIS   Christoph Werner   Parton Dynamics in DIS multi jet events at small x   Magnus Hansson   Di-jets at low x and low Q2   Dan Traynor   Scaled Charged Particles Momentum Distributions at high Q2   Lars Finke   Production of charm and beauty dijets at HERA   Ying-Chun Zhu   Elastic J/Psi production at HERA   Biljana Antunovic   Charged current studies at HERA II   Paul Laycock   F2bb/F2cc at HERA   Benoit Roland   DVCS at HERA   Jan Olsson   Rho Photoproduction at HERA   Carl Gwilliam   Rho production at large t at HERA   Paul Newman   F2D3 and F2D4 measurements   Emmanuel Sauvan   F2D3 new analysis at medium Q2   Olaf Behnke   Diffractive D* and F2D(cc)   Matthias Mozer   Diffractive di-jets and combined fits   Max Klein   FL measurements and low energy running   Dave South   New H1 results on Isolated leptons and Missing PT at HERA   Claude Vallee   Multi-lepton events and search for H++ at HERA   Christian Helebrant Leptoquark searches at HERA   Stefania Xella   Tau lepton production at HERA   Cristinel Diaconu   Search for excited neutrinos at HERA   Christiane Risler   Forward Jet Production in Deep Inelastic Scattering at HERA  

E. Perez DIS’ 06, 20 / 04 / 0629

Backup & Divers

E. Perez DIS’ 06, 20 / 04 / 0630

Azimuthal correlations in dijet low Q2 events

Alternative test of DGLAP in low x DIS:Study the between the two jets closest in to the e.Large kT of gluon broadening of

64 pb-1 (99-00)W.r.t. previous analysis : much larger stat, improved resolution on the HFS measurement.

- O(S3) much better, still low at small

(but large scale errors on the prediction)- Normalising to the x-section integrated over < 170 deg. amplifies the differences (cf H1, Eur. Phys. J. C33 (2004) 477)

- O(S2) unsufficient to describe the data.

i.e. hints that O(S3) not enough

E. Perez DIS’ 06, 20 / 04 / 0631

QCD analysis of LRG

No kinem. dependence of P(0)observed.

Scaling violations at large are drivenby q qg and not g splittings.

i.e. inclusive diff. DIS not muchsensitive to the Dgluon at largeFractional momentum !

E. Perez DIS’ 06, 20 / 04 / 0632

Factorisation in diff. p: D*

Diffractive photoproduction of jets : breaking of factorisation both for theresolved ( ~ expected) and direct (unexpected ?) processes.

Investigate diff. p of D* (direct process largely dominates)

p events : e detected in low angle electron tagger(trigger..) limited statistics

~ 50 pb-1

D*+ D0 +slow K- + +

slow (+c.c.)

Comparison with NLO calculation (FMNR) :Good agreement within the (large) errors.

No evidence for a breakingof factorisation in diff.p of D* mesons.