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14th International Workshop on Deep Inelastic Scattering. Recent Results from the H1 Experiment. Emmanuelle PEREZ DESY & CEA-Saclay. High Q 2 DIS : inclusive measurements searches for new physics, jets Hadronic Final State in low Q 2 NC DIS Diffraction: vector mesons - PowerPoint PPT Presentation
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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.
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