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Tobias Haas: Recent results from HERATobias Haas: Recent results from HERA
The Dynamics of The Dynamics of Proton Structure:Proton Structure: Recent Results Recent Results
from HERAfrom HERA23 August, 200523 August, 2005
Tobias HaasTobias Haas
Deutsches ElektronensynchrotronDeutsches Elektronensynchrotron
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
This TalkThis Talk
Introduction to HERAIntroduction to HERA Standard model physicsStandard model physics
NC/CC electrons/positrons, NC/CC electrons/positrons, +/- helicities+/- helicities
Very high x cross sectionsVery high x cross sections Heavy quarksHeavy quarks FF22, F, F33, F, F22
cc, F, F22bb
Parton densitiesParton densities ααSS(M(MZZ))
EW parametersEW parameters
Beyond the standard Beyond the standard modelmodel Quark compositenessQuark compositeness Contact interactionsContact interactions LeptoquarksLeptoquarks High pHigh pTT leptons leptons
Summary and Summary and conclusionsconclusions
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
: 920 GeV
: 27.5 GeVe±
p
~ 6.3 kmcircumference
50 TeV on fixed target
p
e±
HERA: The Greatest Electron HERA: The Greatest Electron MicroscopeMicroscope
Resolution: 10-18 m
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Luminosity, eLuminosity, e and and polarizationpolarization= HERA II= HERA II
Polarization:Polarization: 50% reached 50% reached
routinely nowroutinely now
> 200 pb> 200 pb-1-1/expt delivered/expt delivered Both lepton speciesBoth lepton species Expect Expect ~ ~ 700 pb700 pb-1-1/expt by /expt by
the end of HERA (2007) the end of HERA (2007)
50%
Po
lari
zatio
n (
%)
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
DIS @ HERADIS @ HERA
Tobias Haas: Recent results from HERATobias Haas: Recent results from HERA
Standard ModelStandard Model
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Neutral Currents
Charged Currents
Charged and Charged and Neutral CurrentsNeutral Currents
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Charged CurrentsCharged Currents SM expectation:
σ±(Pe) = (1± Pe) σ±(Pe =0)
Right-handed currents are absent
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Neutral Currents:Neutral Currents:The ExpectationThe Expectation
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Neutral Currents:
Neutral Currents:
First Results
First Results
30.5 pb-1
53.5 pb-1
Very promising …HERA 2008HERA 2008
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
What do we learn?What do we learn?NC Cross Sections
CC Cross Sections
High ET Jet Cross
SectionsStructure Function Fits
Parton Densities
αS(μ)
EW Parameters
NC
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERAStr
uctu
re F
un
cti
on
sS
tru
ctu
re F
un
cti
on
sxFxF22(x)(x)
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
NC cross section @ very NC cross section @ very high xhigh x
High precision measurement up to x = 1High precision measurement up to x = 1
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
xFxF33(x)(x)
FxY
YF
Y
yF LNC
~~~~3
2
2
duFx vv 2~~3
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
F2cc vs Q2 F2
bb vs Q2
Charm and beauty in the Charm and beauty in the proton?proton?
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
)for corrected(not ~L
bb F
xFxF22b b (x) (x) and and xFxF22
c c (x) (x)
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Parton DensitiesParton Densities
Err
or
on th
e x
g(x
)
Pa
rto
n D
ensi
ties
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
HERA Parton Densities @ HERA Parton Densities @ LHCLHC
Ref: HERA-LHC WS
QC
D
evo
lutio
n
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
SS(M(MZZ))
Simultaneous Simultaneous determination of determination of ααSS(M(MZZ)) and PDFs
Due to inclusion of jet cross sections ααSS(M(MZZ)) and PDFs are NOT strongly correlated
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Precision of Precision of SS(M(MZZ) ) @ HERA@ HERA
HERA
HERA αα SS m
ay soon dominate the world
average
may soon dominate the world
average
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Light quark couplingsLight quark couplings
From H1 PDF fits including additional EW parameters
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
WW Propagator Mass & Propagator Mass & Coupling Coupling GGFF
HERA space-like HERA space-like (q(q22 < 0) mass vs. < 0) mass vs. Tevatron/LEP time-Tevatron/LEP time-like (qlike (q22 >0) one >0) one
SM relationship SM relationship between between MMWW and and GGF F
not usednot used
)PDFs()MQ(
Mx2
GQdxd
)pe(d2W
2 2
4W
2F
2CC
2
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
MMWW and and MMtt in the SM in the SM
178±4.3 GeV80.425±0.038 GeV
• W mass value: MW=80.786 ± 0.205exp GeV
+ the world average MZ indirect determination of
sin2W=1M2W/M2
Z
=0.2151 ± 0.0040exp
• Top quark mass: mt=104 ± 44exp GeV
First determination in DIS at EW scale
Tobias Haas: Recent results from HERATobias Haas: Recent results from HERA
Beyond the SMBeyond the SM
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Are quarks Are quarks “elementary”?“elementary”?
Form factor measurement at Form factor measurement at QQ2 2 ~ 40000~ 40000 GeV GeV22 Resolution 1/Q Resolution 1/Q ~ 10~ 10-16-16 cm = 0.001 proton radiuscm = 0.001 proton radius
Compare measured to expected cross sectionCompare measured to expected cross section Limits on Limits on
quark sizequark size H1:H1:
RRqq < 1.0 x < 1.0 x 1010-16-16 cmcm ZEUS:ZEUS:RRqq < 0.85 x < 0.85 x 1010-16-16 cmcm
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Is there TeV scale physics?Is there TeV scale physics?(Contact Interactions)(Contact Interactions)
Limits on Λ up to 6.2 TeV (Depending on models)
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Are there leptoquarks?Are there leptoquarks?
HERA:HERA: s-channel s-channel eq eq fusionfusion resonance in resonance in eq (eq (ννq) q)
invariant mass in NC invariant mass in NC (CC) events(CC) events
no excess observedno excess observed
TEVATRON:TEVATRON: LQ LQ pair productionpair production
LEP2:LEP2: virtual in evirtual in e++ee--→ → hadronshadrons
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Puzzle: High Puzzle: High ppTT lepton lepton eventsevents Signature:Signature:
lepton + missing lepton + missing ppT T + +
large large ppTT(had)(had)
Dominant SM process:Dominant SM process: on-shell on-shell WW production production
((σσ~1pb~1pb))
Excess seen in HERA I Excess seen in HERA I in H1 for e/in H1 for e/μμ and in and in ZEUS for ZEUS for
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
High High ppTT leptons: Latest leptons: Latest numbers numbers
H1 update with HERA II data H1 update with HERA II data (74 pb(74 pb-1-1 eePP)) 6 new electron events with 6 new electron events with
ppTT(had) > 25 GeV(had) > 25 GeV no new muon eventno new muon event overall excess in overall excess in e+e+μμ channel channel
search at H1search at H1 no excess seen (HERA I only)no excess seen (HERA I only)
23 August 200523 August 2005 Tobias Haas: Recent Results from HERATobias Haas: Recent Results from HERA
Summary and Summary and ConclusionsConclusions
HERA QCD results on structure functions, HERA QCD results on structure functions, pdfs and pdfs and ααSS are becoming me most are becoming me most
precise …precise …… … but HERA is not only a QCD machine:but HERA is not only a QCD machine:
expect important contributions to EW expect important contributions to EW precision measurementsprecision measurements
excellent search potentialexcellent search potential… … the really good stuff is still to come!the really good stuff is still to come!
C. Gwenlan