Presentation is loading. Please wait.

Presentation is loading. Please wait.

Luca Stanco - PadovaLow-x at HERA, Small-x 2007 1 Low-x AND Low Q 2 Luca Stanco – INFN Padova Small-x and Diffraction 2007 Workshop FermiLab, March 28-30,

Published byBryce Curtis Modified over 8 years ago

Similar presentations

Presentation on theme: "Luca Stanco - PadovaLow-x at HERA, Small-x 2007 1 Low-x AND Low Q 2 Luca Stanco – INFN Padova Small-x and Diffraction 2007 Workshop FermiLab, March 28-30,"— Presentation transcript:

1 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 1 Low-x AND Low Q 2 Luca Stanco – INFN Padova Small-x and Diffraction 2007 Workshop FermiLab, March 28-30, 2007 on behalf of H1 and ZEUS collaborations at HERA with JETS

2 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 2 Processes at HERA Electron beam Proton beam x Bj < 1 DIFFRACTION x  = 1 Q 2 > 0 Photon* DIS x  < 1 photon RESOLVED  -PRODUCTION x  = 1 Q 2 = 0 photon DIRECT  -PRODUCTION gluons… quarks PARTONS (defined by Initial States of HARD Scattering) x Bj << 1 low-x regime

3 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 3 Tevatron LHC HERA HERA exploits many (correlated) processes over large kinematic regimes ! X Bj Q2Q2 Low-x “regime” perturbative Non-pert To extrapolate to other regions need to take care of low-x effects: saturation multiple interactions QCD DYNAMICS (DGLAP vs BFKL evolutions) study at HERA:

4 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 4...if nobody else have already shown... Gluons and QCD dynamics

5 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 5 Outline of the talk: a little bit of theory, modelling, Monte Carlo’s… ”Forward” Jets in DIS H1 (1997 data, final analysis) ZEUS (1998/00 data, preliminary analysis) Multi Jets in DIS H1 (1999/00 data, preliminary analysis) ZEUS (1998/00 data, preliminary analysis) Hard FORWARD Jets (near proton direction where effects of gluon radiation should be largest - A. Mueller 1990)

6 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 6 before going into physics, let us look at the environment... HeraI: H1 and ZEUS took about 130 pb -1 2001 “luminosity upgrade” 2002/03 background problems 2004 positrons (50 pb -1 ) 2005: electrons 2006: positrons 2007: from March HERA for Low Energy Run (F L measure) END of HERA  next PETRAIII Results on JETS mainly from HERA-I (up till now) H1 and ZEUS will end up with ~ 0.5 fb -1, each Luminosity growth at HERA (I: 92-00, II: 03-07)

7 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 7 QCD dynamics: Evolution & Resummation HERA: DIS at low-x Bj down to 10 -5  large  *p center of mass energy (W ~ 1/x )

8 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 8 saturation Inclusive F2 measurement not able to discriminate between different QCD dynamics  Study of Hadronic Final States (JETS)

9 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 9...if nobody else is going to show... Definitively, physics has to be clarified. even if we consider Structure Functions results at low-x

10 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 10  FORWARD JETS (proton direction) possibility to study parton dynamics, by looking for effects beyond DGLAP HERA extends x Bj until 10 -5 (with jets until 10 -4 ) Where ? in the BREIT frame: where virtual boson is enterely spacelike at lowest order, quark is back scattered Caveat: different Monte Carlo models not fully clear where applicable

11 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 11 JETS observables in the BREIT Frame … more technically

12 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 12 NLO pQCD calculations and interfaced to various PDFs (like CTEQ, MRST) Parton Level cross sections – need to rely on LO MC for hadronisation corrections

13 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 13 LO-DGLAP fails completely ! NLO-DGLAP well below data at low-x Monte Carlo models with extra parton radiation provide an improved description of the data inclusion of a resolved-photon component (RAPGAP: DI+RES) parton emissions not ordered in k T (CDM) H1 data in the kinematic region: FORWARD JETS L=13.7 pb -1 10 -4 <x<4. 10 -3 and 5<Q 2 <85 GeV 2 0.5 < (p T,jet ) 2 /Q 2 < 2 to suppress DGLAP and enhance BFKL

14 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 14 ZEUS data less striking… FORWARD JETS L=81.8 pb -1 E  jet >5 GeV, 2<  jet <3.5 4. 10 -4 <x<5. 10 -3 and 20<Q 2 <100 GeV 2 0.5 < ( E  jet ) 2 /Q 2 < 2

15 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 15 Is it a HERA business ? or HERA phase space too limited to distinguish between different evolution models ? ZEUS data less striking… (NLO(  S 2 )-DISENT MC below the data but within theoretical errors)  needs of next NLO ? ( but ZEUS uses  R 2 =Q 2, while H1 takes  R 2 = ) FORWARD JETS

16 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 16 Very detailed investigation from H1 to enhance BFKL phase space: Compute differential cross-sections of  1 &  2 Select dijets plus forward-jet different  1 and  2 regions affect: Kt-ordering Gluon radiation Evolution chain

17 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 17 Data towards NLO too little Phase Space for NLO FORWARD JETS

18 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 18 Data towards CCFM Data towards CDM and  res  res not sufficient … CDM may mimic BFKL evolution … NO description ! FORWARD JETS

19 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 19 MULTIJETS (dijets, trijets) ANALYSIS Kinematic selection to enhance (unordered) gluon radiation and to study parton dynamics (at low-x) H1:  Ldt = 44.2 pb -1 10 -4 <x Bj <10 -2, 5<Q 2 <80 GeV 2 ZEUS:  Ldt = 82.2 pb -1 10 -4 <x Bj <10 -2, 10<Q 2 <100 GeV 2 Hadronic Center-of-Mass (like Breit-frame boosted) Comparisons with NLO at order O(  S 2 ) and O(  S 3 ) NLOJET, DISENT Conparisons with Monte Carlo’s LO-PS with/out  res (CDM-DJANGOH, RAPGAP) H1 compares to parton level, ZEUS compares to hadron level

20 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 20 All the sample: H1 Low-x region: more DATA than NLO predicted MULTIJETS LO discrepancy E  *> 4 GeV, E  1 *+E  2 *> 9 GeV Overall systematics error of 19% not included on DATA -1 <  jet < 2.5

21 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 21 H1 Select TWO subsamples with Forward JETS (  jet 0.035) Two central jets plus one forward One central jets plus two forward NLO++ comparison NLO at O(  S 3 ) describes well the TWO central jets, expected to be produced from hard scattering MULTIJETS -1 <  jet < 1 FORWARD jets are expected to be produced from gluon radiation

22 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 22 LO Monte Carlo’s comparison H1 Resolved contribution NOT working ! RAPGAP: direct+resolved contributions MULTIJETS

23 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 23 ZEUS Reasonable description by NLO JET MULTIJETS Hadron Level Jet energy scale uncertainty E*  1 > 7 GeV, E*  2,3 > 5 GeV -1 <  jet < 2.5  R 2 =  F 2 = ( 2 +Q 2 )/4

24 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 24 ZEUS MULTIJETS NLO JET comparison with Dijets DATA NLO consistent within errors 10 15 GeV 2 20 30 GeV 2 O(  S 2 ) does not describe DATA

25 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 25 ZEUS NLO JET comparison with Trijets DATA … but theor. errors (  F,  R ) too large Need next order MULTIJETS

26 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 26 Conclusions low-x Bj regime unsettled at HERA Multijets (Forward) production measured in x BJ >10 -4 and Q 2 <100 GeV 2 Statistical ~ Theoretical errors (NLO) need more data and theory computations unordered gluon emission significant at low-x ? A VERY EXCITING FIELD WHERE TO LOOK DEEPLY INSIDE QCD PARTON EVOLUTION DYNAMICS

27 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 27 Backup Slides

28 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 28 Kinematics of Neutral Current (NC) Deep Inelastic Scattering (DIS) W:  *P c.o.m. energy

29 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 29 WHY studying pQCD ? at least 4 answers: 1.NOT TRUE it is so well understood.. 2.Strong coupling,  S, measurement (see next talk) 3.Parton Density Functions measurements 4.Parton evolutions From HERA-LHC workshops, examples of uncertainties,

30 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 30 Z.Czyczula et al., p T of Higgs (120 GeV) from different Parton-Showers (PS) models and QCD scale choices Uncertainties: up to 170% due to PS (which evolution type ? which ordering ?) up to 100% due to the choice of QCD scale (Q 2, m 2, ŝ etc.)  low-x and forward jets…

31 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 31 two different parton ladders….  Expect more energetic jets in forward region (LEPTO, DISENT) (~ColorDipM) (CASCADE)

32 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 32 JETS in DIS The BREIT frame ! Frame where virtual boson is enterely spacelike At lowest order, quark is back scattered In pratice, high Et jet events must be at least of order  S

33 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 33 Jets Production in NC Deep Inelastic Scattering

34 Luca Stanco - PadovaLow-x at HERA, Small-x 2007 34 5 jets event at low-x (H1)

Download ppt "Luca Stanco - PadovaLow-x at HERA, Small-x 2007 1 Low-x AND Low Q 2 Luca Stanco – INFN Padova Small-x and Diffraction 2007 Workshop FermiLab, March 28-30,"

Similar presentations

Luca Stanco - Padova Heavy Quarkonium, Fermilab 1 Charmonium Production at HERA Luca Stanco – INFN Padova Outline: Introduction J/  Production Mechanisms.

Luca Stanco - Padova Heavy Quarkonium, Fermilab 1 Charmonium Production at HERA Luca Stanco – INFN Padova Outline: Introduction J/  Production Mechanisms.
ZEUS high Q 2 e + p NC measurements and high-x cross sections A.Caldwell Max Planck Institute for Physics On behalf of the ZEUS Collaboration Allen Caldwell.

ZEUS high Q 2 e + p NC measurements and high-x cross sections A.Caldwell Max Planck Institute for Physics On behalf of the ZEUS Collaboration Allen Caldwell.
Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 1 Non-SUSY Searches at HERA Peter Schleper Hamburg University SUSY07 July 27, 2007.

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 1 Non-SUSY Searches at HERA Peter Schleper Hamburg University SUSY07 July 27, 2007.
29.6.2005Low x meeting, Sinai 20051 Alice Valkárová on behalf of H1 collaboration LOW x meeting 2005, Sinaia H1 measurements of the structure of diffraction.

Low x meeting, Sinai Alice Valkárová on behalf of H1 collaboration LOW x meeting 2005, Sinaia H1 measurements of the structure of diffraction.
Low x workshop Helsinki 2007 Joël Feltesse 1 Inclusive F 2 at low x and F L measurement at HERA Joël Feltesse Desy/Hamburg/Saclay On behalf of the H1 and.

Low x workshop Helsinki 2007 Joël Feltesse 1 Inclusive F 2 at low x and F L measurement at HERA Joël Feltesse Desy/Hamburg/Saclay On behalf of the H1 and.
May 2005CTEQ Summer School1 Global Analysis of QCD and Parton Distribution Functions Dan Stump Department of Physics and Astronomy Michigan State University.

May 2005CTEQ Summer School1 Global Analysis of QCD and Parton Distribution Functions Dan Stump Department of Physics and Astronomy Michigan State University.
ISDM 2005, Kromeriz Kamil Sedlak, Jets in photoproduction at HERA 1 Jets in Photoproduction & at low Q 2 at HERA On behalf of the H1 and ZEUS Collaborations.

ISDM 2005, Kromeriz Kamil Sedlak, Jets in photoproduction at HERA 1 Jets in Photoproduction & at low Q 2 at HERA On behalf of the H1 and ZEUS Collaborations.
1 Pierre Marage Univ. Libre de Bruxelles On behalf of the H1 and ZEUS collaborations Diffraction at HERA CIPANP 2006 Puerto-Rico 29/5-4/6/2006.

1 Pierre Marage Univ. Libre de Bruxelles On behalf of the H1 and ZEUS collaborations Diffraction at HERA CIPANP 2006 Puerto-Rico 29/5-4/6/2006.
Forward Jet Production at HERA, Patrick Ryan, Univ. of Wisconsin EPS2005, July 21, 2005 - 1 Patrick Ryan University of Wisconsin On Behalf of the H1 and.

Forward Jet Production at HERA, Patrick Ryan, Univ. of Wisconsin EPS2005, July 21, Patrick Ryan University of Wisconsin On Behalf of the H1 and.
QCD Studies at HERA Ian C. Brock Bonn University representing the ZEUS and H1 Collaborations.

QCD Studies at HERA Ian C. Brock Bonn University representing the ZEUS and H1 Collaborations.
Karlheinz Meier - Kirchhof-Institut für Physik - Heidelberg University - Vth Workshop on Small-x and Diffractive Physics - Fermilab - September 2002 Odderon.

Karlheinz Meier - Kirchhof-Institut für Physik - Heidelberg University - Vth Workshop on Small-x and Diffractive Physics - Fermilab - September 2002 Odderon.
25 th of October 2007Meeting on Diffraction and Forward Physics at HERA and the LHC, Antwerpen 1 Factorization breaking in diffraction at HERA? Alice Valkárová.

25 th of October 2007Meeting on Diffraction and Forward Physics at HERA and the LHC, Antwerpen 1 Factorization breaking in diffraction at HERA? Alice Valkárová.
Ursula Bassler, LPNHE-Paris, RUN II MC workshop 1 Monte Carlo Tuning: The HERA Experience Monte Carlo Models for DIS events Description of inclusive hadronic.

Ursula Bassler, LPNHE-Paris, RUN II MC workshop 1 Monte Carlo Tuning: The HERA Experience Monte Carlo Models for DIS events Description of inclusive hadronic.
Erik MaddoxBEACH 2004, Chicago1 Heavy flavour production at HERA Outline: Introduction Charm production Beauty production Conclusions Erik Maddox (NIKHEF/UvA)

Erik MaddoxBEACH 2004, Chicago1 Heavy flavour production at HERA Outline: Introduction Charm production Beauty production Conclusions Erik Maddox (NIKHEF/UvA)
M.KapishinDiffraction using Proton Spectrometers at HERA 1 Results on Diffraction using Proton Spectrometers at HERA Low-x Meeting: Paphos, Cyprus, June.

M.KapishinDiffraction using Proton Spectrometers at HERA 1 Results on Diffraction using Proton Spectrometers at HERA Low-x Meeting: Paphos, Cyprus, June.
R.Carlin 2006 Aspen Winter Conference HERA for LHC Roberto Carlin University of Padova and INFN-PD.

R.Carlin 2006 Aspen Winter Conference HERA for LHC Roberto Carlin University of Padova and INFN-PD.
1 Methods of Experimental Particle Physics Alexei Safonov Lecture #14.

1 Methods of Experimental Particle Physics Alexei Safonov Lecture #14.
High E T Jet Physics at HERA José Repond Argonne National Laboratory On behalf of the H1 and ZEUS collaborations Small-x Workshop, Fermilab, March 28-30,

High E T Jet Physics at HERA José Repond Argonne National Laboratory On behalf of the H1 and ZEUS collaborations Small-x Workshop, Fermilab, March 28-30,
M.KapishinDiffraction and precise QCD measurements at HERA 1 Rencontres de Moriond QCD 2012 M.Kapishin, JINR on behalf of the H1 and ZEUS Collaborations.

M.KapishinDiffraction and precise QCD measurements at HERA 1 Rencontres de Moriond QCD 2012 M.Kapishin, JINR on behalf of the H1 and ZEUS Collaborations.
Inclusive Jets in ep Interactions at HERA, Mónica V á zquez Acosta (UAM) HEP 2003 Europhysics Conference in Aachen, July 19, 2003 - 1 Mónica Luisa Vázquez.

Inclusive Jets in ep Interactions at HERA, Mónica V á zquez Acosta (UAM) HEP 2003 Europhysics Conference in Aachen, July 19, Mónica Luisa Vázquez.

Similar presentations

Ads by Google