Studies of the hadronic final state with the H1

detectorDaniel Traynor, QMUL

1

Recent Results from H1

• Photoproduction of Dijets with High Transverse Momenta at HERA.

• Multi-jet production in high Q2 neutral current deeply inelastic scattering at HERA and determination of αs

• H1 Search for a Narrow Baryonic Resonance Decaying to K0s p(p)

• Measurements of Forward Jet Production at low x in DIS

2

Recent Results from H1

• Photoproduction of Dijets with High Transverse Momenta at HERA.

• Multi-jet production in high Q2 neutral current deeply inelastic scattering at HERA and determination of αs

• H1 Search for a Narrow Baryonic Resonance Decaying to K0s p(p)

• Measurements of Forward Jet Production at low x in DIS

2

HERA + H1

3

4

electrons

27.6 GeV

4

electrons

27.6 GeV

Protons

920GeV

4

electrons

27.6 GeV

Protons

920GeV

4

electrons

27.6 GeV

Protons

920GeV

4

H1

s.c. Solenoid 1.16 T

Liquid Argon Calorimeter

Instrumented Iron Detector Forward Muon

Spectrometer

GO GG

Forward

Tracker

Central

Tracker

Silicon

Tracker

Spaghetti

Calorimeters

ep

Central

MWPCs

Backward

MWPC

ToF

Scintillators

920 GeV27.6 GeV

5

Forward Jet Production at HERA

6

Inelasticity yy = p.q / p.k`

s = Q2 / xy = 318 GeV

KinematicsFour-momentum transfer

squaredQ2 =-q2 = (k-k`)2

Bjorken x (xbj)x = Q2 / 2p.q

Kinematics overstrainedcalculable from electron or proton side

e+ e’+

!

p

q

Q2

xbj

e+(k)e+(k`)

qP

γ

7

xi = longitudinal momentum fractionkt = transverse momentum

Parton Evolution

8

Monte Carlo and NLO predictions

9

xBj xBj small

evolution from largeto small x

"forward" jet

x =E

= largejet

jet

Eproton

Suppress DGLAP Pt,jet2 ~ Q2

Opens up phase space to BFKL type emissions

xjet >> xbj

kinematic acceptance xbj ~ 10-4, θjet(lab) > 7o, ηjet < 3.0

Forward Jet takes large fraction of proton

momentum

Enhancing non-DGLAP Parton Emmisions

mor

e fo

rwar

d

10

Event selection

Ee′ > 10 GeV156o < θe′ < 175o

0.1 < y < 0.70.0001 < xbj < 0.004

5 GeV2 < Q2 < 85 GeV2

pt,jet > 3.5 GeV7.0o < θjet(lab) < 20o

xjet > 0.035

Inclusive kt jet algorithm in Breit frame

11

H1 prelim.

E scale uncert

NLO di-jet 1+!HAD

0.5!r,f"!

r,f"2!

r,f

PDF uncert.

LO di-jet1+!

HAD

H1 forward jet data

xBj

d"

/ d

xB

j (n

b)

0

250

500

750

1000

0.001 0.002 0.003 0.004

NLO = DISENT

μr2 = ET2 of Jetμf2 = <ET2> = 45 GeV2

PDF = CTEQ6M

NLO significantly below data

Is scale uncertainty large enough?

Large difference from LO to NLO predictions!

Inclusive Forward Jet Production

0.5 < pt,jet2 /Q2 < 5

12

H1 Prelim.

E. scale uncert.

RG-DIR

CDMRG-DIR+RES

CASC set1

CASC set2

H1 forward jet data

xBj

d!

/ d

xB

j (n

b)

0

250

500

750

1000

0.001 0.002 0.003 0.004

Significant improvement in RapGap (DGLAP) description if resolved photon interactions

included

CDM similar model to RG-DIR+RES

Both still too low at low xbj

CASCade shape wrong!Predictions sensitive to proton

PDF used.

Inclusive Forward Jet Production

13

Triple Differential Cross Sections

0

7

14

0

0.5

1

0

0.025

0.05

0

1.1

2.2

0

0.2

0.4

0

0.0115

0.023

0

0.07

0.14

0.0001 0.001

0

0.014

0.028

0.0001 0.002

5!Q2!10

12

.25!p

t2!3

5

H1 prelim.E scale uncertNLO di-jet 1+!

HAD0.5"

r,f!"

r,f!2"

r,f+PDF uncert.

LO

!r#=3.5

a)

10!Q2!20

0.6!r!3.5!r#=1.8

b)

20!Q2!85

0.1!r!1.8!r#=0.8

c)

35!p

t2!9

5

3.5!r!19!r#=8.1

d)

d"

/ d

xd

Q2d

pt2

(n

b G

eV

-4)

1.8!r!9.5!r#=4.2

e)

0.4!r!4.8!r#=1.8

f)

95!p

t2!4

00

9.5!r!80!r#=22.2

g)

xBj

4.8!r!40!r#=11.3

h)

xBj

1.1!r!20!r#=4.9

i)

xBj

0

0.0012

0.0025

0.001 0.004

Good description at high Q2, high

Pt,jet2 and high xbj

Additional emissions needed at low Q2, pt,jet2, xbj

r = ptjet2/Q2

14

0

5.5

11

0

0.475

0.95

0

0.03

0.06

0

1.1

2.2

0

0.18

0.36

0

0.0132

0.0265

0

0.105

0.21

0.0001 0.001

0

0.02

0.04

0.0001 0.002

5!Q2!10

12

.25!p

t2!3

5

RGDIR

CDMRGtot

CAS1CAS2

H1 prelim.E.scale uncert

1.2!r!7

a)

10!Q2!20

0.6!r!3.5

b)

20!Q2!85

0.1!r!1.8

c)

35!p

t2!9

5

3.5!r!19

d)

d!

/ d

xd

Q2d

pt2

(n

b G

eV

-4)

1.8!r!9.5

e)

0.4!r!4.8

f)

95!p

t2!4

00

9.5!r!80

g)

xBj

4.8!r!40

h)

xBj

1.1!r!20

i)

xBj

0

0.0012

0.0023

0.001 0.004

Triple Differential Cross Sections

RG DIR Fails

RG DIR+RES Better

CDM good problems at high

pt,jet2

CAScade wrong shape,

sensitivity to PDF

15

!!"#$"!!

%&

!'()!!"#

"!"

!!"#*

%&

!!"#$

!!"#*

!'()!!"#

"!!

"!"

Forward Jet + Dijet

Two central jets (pt > 6GeV) + Forward Jet

Δη1 < 1, xg small, Δη2 large,

room for BFKL ladder

Δη > 1, Δη2 small, shorter

ladder, less BFKL like

16

!"2

d#

/d!"

2

All !"1

H1 Prelim.

E.scale uncert.

RG-DIR

CDMRG TOT

CASC set1CASC set2

0

0.02

0.04

0.06

0 1.5 3

!"2

d#

/ d!"

2 (

nb

)

!"1!1

0

0.0165

0.033

0 2 !"2

d#

/ d!"

2 (

nb

)

!"1!1

0

0.0175

0.035

0 2

!"1!1

!"2

d#

/ d!"

2 (

nb

)

0

0.01

0.02

0 1.5 3

!"1!1

!"2

d#

/ d!"

2 (

nb

)

0

0.01

0.02

0.03

0 1.25 2.5

H1 prelim.

E scale uncert0.5!

r,f"!

r,f"2!

r,fPDF uncert.

!"2

d#

/d!"

2

All !"1

0

0.035

0.07

0 2

scale uncertainties

large

3 jet predictions from NLOJET++

no model able to work in all phase space

17

Photoproduction of Dijets with high

Transverse Momenta at HERA

18

e

p

y, Q2

x!

xP

ME

PDF

PDF

Jet

Jet

photon remnant

proton remnant

Q2 <1 GeV2

Photoproduction

xγ < 0.8 → resolved

xγ > 0.8 → direct

Experimentallyno electron seen

19

QCD Models

PYTHIA 6.1Born level QCD matrix elements of hard processes

+ minimum pt cutoff + LO proton (CTEQ5L) PDF

+ photon (GRV-LO) PDF+ leading log parton shower models

+ multiple interactions + string hadronisation

only contain 2→2 photoproduction processeshave to apply scale factor 1.2 (1.55 for HERWIG)

Only PYTHIA shown, HERWIG very simmilar

20

NLO Calculations

Factorisation and renormalisation scale (μf μr) set to sum of pt of outgoing partons /2

pQCD NLO jet cross sections on parton level obtained from programs

by Frixione + Ridolfi

proton PDF = CTEQ6Mphoton PDF = GRV-HO

Hadronisation correction (δhad) from Monte Carlo

21

Event Selection

|ZVTX| < 35 cmpt,miss < 20 GeV

non-ep topological background finder

no identified scattered electronjet mass > 2 GeV

Not (Jet in φ crack and jet size < 0.05)pt,jet > 25 GeVpt,jet2 > 15 GeV

-0.5 < ηjet < 2.750.1 < yJB < 0.9

22

DIR ∝ (1-cosθ)-1RES ∝ (1-cosθ)-2

Mjj >

65

GeV

[pb]

!/d

cos

"d

20

40

60

80

100

120

140

160

[pb]

!/d

cos

"d

20

40

60

80

100

120

140

160 < 0.8#x

H1 prel.NLO

)had$ (1+×NLO 1.2×Pythia

[pb]

!/d

cos

"d

20

40

60

80

100

120

140

160

[pb]

!/d

cos

"d

20

40

60

80

100

120

140

160 > 0.8#x

*!cos 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

[pb]

!/d

cos

"d

0

10

20

30

40

50

60

70

80

90

*!cos 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

[pb]

!/d

cos

"d

0

10

20

30

40

50

60

70

80

90

> 65GeVJJM

*!cos 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

[pb]

!/d

cos

"d0

10

20

30

40

50

60

70

80

90

*!cos 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

[pb]

!/d

cos

"d0

10

20

30

40

50

60

70

80

90

> 65GeVJJM

xγ < 0.8 xγ > 0.8COSθ*

cosθ* = |tanh(η1-η2)/2| Scale+PDFScale

23

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

100

200

300

400

500

600

700

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

100

200

300

400

500

600

700

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

< 0.1p

x

H1 prel.

NLO

)had# (1+!NLO

1.2!Pythia

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

350

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

350 > 0.1p

x

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

< 0.8!x

H1 prel.

NLO

)had# (1+!NLO

1.2!Pythia

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310 > 0.8!xphoton - gluon photon - quark

nlo dominated by the scale uncertainty

xγ

24

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

100

200

300

400

500

600

700

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

100

200

300

400

500

600

700

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

< 0.1p

x

H1 prel.

NLO

)had# (1+!NLO

1.2!Pythia

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

350

!x0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

[p

b]

!/d

x"

d

0

50

100

150

200

250

300

350 > 0.1p

x

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

< 0.8!x

H1 prel.

NLO

)had# (1+!NLO

1.2!Pythia

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x"

d

1

10

210

310 > 0.8!x

xp

high xp sensitive to proton PDF

scale uncertainty smallest

high xp - high jet η

25

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-310

-210

-110

1

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-310

-210

-110

1

< 1 1,2"

< 0.8#xH1 prel.

NLO

)had$ (1+!NLO

1.2!Pythia

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-310

-210

-110

1

10

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-310

-210

-110

1

10

> 1 j" < 1,

i"

< 0.8#x

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-210

-110

1

10

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-210

-110

1

10

> 1 1,2"

< 0.8#x

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-310

-210

-110

1

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-310

-210

-110

1

< 1 1,2"

> 0.8#xH1 prel.

NLO

)had$ (1+!NLO

1.2!Pythia

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-210

-110

1

10

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-210

-110

1

10

> 1 j" < 1,

i"

> 0.8#x

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-210

-110

1

[GeV]t,max

p30 40 50 60 70 80

[p

b/G

eV

]t,

ma

x/d

p!

d

-210

-110

1

> 1 1,2"

> 0.8#x

pt,max

26

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

< 1 1,2"

< 0.8#xH1 prel.

NLO

)had$ (1+!NLO

1.2!Pythia

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

-210

-110

1

10

210

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

-210

-110

1

10

210

> 1 j" < 1,

i"

< 0.8#x

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

> 1 1,2"

< 0.8#x

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

< 1 1,2"

> 0.8#xH1 prel.

NLO

)had$ (1+!NLO

1.2!Pythia

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

-210

-110

1

10

210

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

-210

-110

1

10

210

> 1 j" < 1,

i"

> 0.8#x

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

Px

0.1 0.2 0.3 0.4 0.5 0.6 0.7

[p

b]

p/d

x!

d

1

10

210

> 1 1,2"

> 0.8#x

xp

27

)2

(GeV2

Q

310

410

)2

(p

b/G

eV

2 / d

Q!

d

-510

-410

-310

-210

-110

1

Dijets

Trijets)

had"(1+.NLO

< 4.02 / Q2

r,f!0.25 <

> 5 GeVT,jet

BreitE

< 2.5jet

Lab#-1 <

> 25 GeV3jet

, M2jet

M

H1 Preliminary 99-00

-exchange only)$ (

)2

(GeV2

Q

310

410

)2

(p

b/G

eV

2 / d

Q!

d

-510

-410

-310

-210

-110

1

Multi-jet production in high Q2 neutral current deeply inelastic scattering at HERA and determination of αs

H1prelim-05-033

28

)2

(GeV2

Q

310

410

)2

(p

b/G

eV

2 / d

Q!

d

-510

-410

-310

-210

-110

1

Dijets

Trijets)

had"(1+.NLO

< 4.02 / Q2

r,f!0.25 <

> 5 GeVT,jet

BreitE

< 2.5jet

Lab#-1 <

> 25 GeV3jet

, M2jet

M

H1 Preliminary 99-00

-exchange only)$ (

)2

(GeV2

Q

310

410

)2

(p

b/G

eV

2 / d

Q!

d

-510

-410

-310

-210

-110

1

)2

(GeV2

Q

310

410

dijet

! /

trijet

! =

3/2

R

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

H1 Preliminary 99-00

)had"NLO (1+

-exchange only)#(

< 4.02 / Q2r,f!0.25 <

Hadronisation Uncertainty

)2

(GeV2

Q

310

410

dijet

! /

trijet

! =

3/2

R

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

Multi-jet production in high Q2 neutral current deeply inelastic scattering at HERA and determination of αs

H1prelim-05-033

28

)2

(GeV2

Q

310

410

)2

(p

b/G

eV

2 / d

Q!

d

-510

-410

-310

-210

-110

1

Dijets

Trijets)

had"(1+.NLO

< 4.02 / Q2

r,f!0.25 <

> 5 GeVT,jet

BreitE

< 2.5jet

Lab#-1 <

> 25 GeV3jet

, M2jet

M

H1 Preliminary 99-00

-exchange only)$ (

)2

(GeV2

Q

310

410

)2

(p

b/G

eV

2 / d

Q!

d

-510

-410

-310

-210

-110

1

)2

(GeV2

Q

310

410

dijet

! /

trijet

! =

3/2

R

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

H1 Preliminary 99-00

)had"NLO (1+

-exchange only)#(

< 4.02 / Q2r,f!0.25 <

Hadronisation Uncertainty

)2

(GeV2

Q

310

410

dijet

! /

trijet

! =

3/2

R

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

αs(MZ) = 0.1175 ± 0.0017 (stat.) ± 0.0050 (syst.) {+0.0054}{-0.0068} (th.)

)2

(GeV2

Q

310

410

s!

0.1

0.12

0.14

0.16

0.18

0.2

0.22

)2

(GeV2

Q

310

410

s!

0.1

0.12

0.14

0.16

0.18

0.2

0.22

H1 Preliminary 99-00

)2

(Qs!

)Z(Ms!Averaged

World Average (PDG):

0.0020!) = 0.1187 Z(Ms!

Multi-jet production in high Q2 neutral current deeply inelastic scattering at HERA and determination of αs

H1prelim-05-033

28

H1 Search for a Narrow Baryonic Resonance Decaying to K0s p(p)

H1prelim-05-031

1.45 1.5 1.55 1.6 1.65 1.7 1.75 1.8

20

30

40

50

60

70

80

90

100

p)[GeV]S

0M(K

N/5

Me

V

H1 preliminary

H1 databgr fit

29

H1 Search for a Narrow Baryonic Resonance Decaying to K0s p(p)

H1prelim-05-031

1.45 1.5 1.55 1.6 1.65 1.7 1.75 1.8

20

30

40

50

60

70

80

90

100

p)[GeV]S

0M(K

N/5

Me

V

H1 preliminary

H1 databgr fit

Upper limit on cross section at 1520MeV is

roughly 100pb, does not exclude ZEUS observation

1.45 1.5 1.55 1.6 1.65 1.70

20

40

60

80

100

120

140

160

))[GeV]pp(S

0M(K

))[p

b]

pp

(0

->K

+!(

U.L

."

2<100 GeV

220<Q

low momentum dE/dx selection

H1 prel.

95 % C.L.

10 MeV!int. window = 16 MeV!int. window =

29

Summary

• Studies of Forward Jets show need for additional terms beyond present collinear DGLAP

• New results on the photoproduction of high Et dijets, sesitive to the proton PDF, have been made.

30

JET PRODUCTION IN DIFFERENT EVOLUTION SCHEMES

DGLAP

DGLAP direct photon

DGLAP

DGLAP resolved photon

DGLAP

CCFM or BFKL

DGLAP: strong ordering of parton kTCCFM: angular ordering of parton emissions (“unintegrated” PDF)BFKL: strong ordering in xi (“unintegrated” PDF)

JET PRODUCTION IN DIFFERENT EVOLUTION SCHEMES

DGLAP

DGLAP direct photon

DGLAP

DGLAP resolved photon

DGLAP

CCFM or BFKL

DGLAP: strong ordering of parton kTCCFM: angular ordering of parton emissions (“unintegrated” PDF)BFKL: strong ordering in xi (“unintegrated” PDF)

JET PRODUCTION IN DIFFERENT EVOLUTION SCHEMES

DGLAP

DGLAP direct photon

DGLAP

DGLAP resolved photon

DGLAP

CCFM or BFKL

DGLAP: strong ordering of parton kTCCFM: angular ordering of parton emissions (“unintegrated” PDF)BFKL: strong ordering in xi (“unintegrated” PDF)

Parton Dynamics in DIS

Strong ordering in kt of parton

emissions

angular ordering of parton emissions

31