Precise measurement of Charm Dimuon production cross-section in ?N interactions and its various applications

1
Precise measurement of Charm Dimuonproduction
cross-section in ?N interactionsand its various
applications

• Oleg Samoylov (DLNP) _at_ 111th Scientific Council,
  Feb. 16, 2012

2
Motivation of the Charm Dimuons
Charge current (CC)
Neutral current (NC)
qu (?)
qd (l)
f
f'
g
g / Cos ?W
W
Z0
g e / Sin ?W
Electro-weak interections in Standard Model (SM)
NuTeV analysis Sin2?W 1 - MW2/MZ2 0.2277
0.0013 (stat.) 0.0009 (syst.) R?
s?NC / s?CC 0.3916 0.0013 (SM 0.3950)
R? s?NC / s?CC 0.4050 0.0027 (SM 0.4066)
3
Motivation of the Charm Dimuons
NuTeV
Roberto Petti for the NOMAD
4
A direct probe of the Strange sea
Proton structure is defined by Parton
Distribution Functions (PDFs) of quarks q(x) and
gluons g(x)
?µN ? µ-µ X
?µs ? µ-c ? µ-µ X
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Available charm dimuon data
?µN ? µ-µ X ? ?µs ? µ-c ? µ-µ X
Experiment Pubication Charm dimuons Neutrino Energy, GeV
CDHS Jun.1982 9 922 30-250 (20)
CHARM II Oct. 1999 3 100 35-290 (24)
NOMAD Jul. 2000 2 714 14-300 (27)
NuTeV Feb. 2001 5 102 20-400 (157.8)
CCFR Feb. 2001 5 030 30-600 (150)
CHORUS Apr. 2008 8 910 15-240 (27)

• Strange sea PDF s(x) based on approx. 10 000
  events only

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Neutrino induced charm dimuons

• ?-induced charm dimuon production

Dc S fh Dch, Bµ S fh B (h ? µ X), h D0,
D, Ds, ?

• Charm production in (anti)neutrino DIS provides
• a clean and direct access to s(x)

Vcs20.95 Vcs20.05
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NOMAD experiment at CERN SPS
1995-1998
Front Calorimeter (FCAL)
Muon neutrino beam
NOMAD logo
Short baseline ?µ??t oscillation experiment
(620m)
NIM A 515 (2003) 800-828
Drift Chambers (DCH)
NIM A 404 (1998) 96-128

• 1. Largest samples of neutrino interactions
  currently available
• - 20 M events with Iron in Front Calorimeter (50
  k dimuons)
• - 2.5 M events with Carbon in Drift Chambers
• 2. Resolution for the vertexes
• in Drift Chambers 0.1 0.25 cm and in Front
  Calorimeter 0.6 1.0 cm
• 3. Excellent reconstruction quality of individual
  (charged) tracks ?p/p3.5, e95
• 4. Good calorimetry for ECAL ?E/E3.2/EGeV,
  for FCAL and HCAL ?E/E104/EGeV

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Reconstruction of the dimuon events
E? Eµ- Eµ Ehad
Event information E? 81.4 GeV Eµ- 32.6
GeV Eµ 19.0 GeV Mµµ 0.945 GeV Q2 3.26
GeV2 W2 89.4 GeV2
Background
Signature Stat. Eff.,
?µ CC 8 759 065 65.8
µ-µ 20 480 22.5
µ-µ- 7 150 22.5
Charm dimuon
Charm dimuon exp. DATA and Bg. subtraction
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Relevance of the NOMAD dimuon data
?µN ? µ-µ X ? ?µs ? µ-c ? µ-µ X
Experiment Pubication Charm dimuons Neutrino Energy, GeV
CDHS Jun.1982 9 922 30-250 (20)
CHARM II Oct. 1999 3 100 35-290 (24)
NOMAD Jul. 2000 2 714 14-300 (27)
NuTeV Feb. 2001 5 102 20-400 (157.8)
CCFR Feb. 2001 5 030 30-600 (150)
CHORUS Apr. 2008 8 910 15-240 (27)
NOMAD 2011 15 340 6-300 (27)

• The NOMAD has the largest sample of ?-induced
  charm dimuons
• The neutrino energies closest to the charm
  production threshold

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Charm dimuon X-section measurement

• Measure RATIO of cross-sections to reduce
  systematics
• Rµµ sµµ /scc ? Nµµ /Ncc (x) x E? , xBj ,
  vs
• Require leading µ- and Q2 1 GeV2
• ? sµµ f dx dy dE? 5.15 0.05 10-3 ?µ CC
• Total systematic uncertainty (17 different
  sources) 2
• Agreement with model calculation based upon
  global PDF fit with NuTeVCCFR dimuon data
  only

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Sensitivity to the Strange sea

• Add NOMAD sµµ /scc to global PDF ?t with NuTeV
  and CCFR dimuon data
• S. Alekhin, R.Petti
• Consistency of central values
• Reduction of s(x) uncertainty by a factor 2 down
  to 3

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Strange sea and c-quark parameters

• Charm quark mass and strange sea supression factor

Experiments mc (mc), GeV ?s (SS)/(UD)
E531 NuTeV CCFR 1.010 0.095 0.62 0.005
E531 NOMAD 1.058 0.059 0.63 0.004
E531 NuTeV CCFR NOMAD 1.070 0.067 0.61 0.002
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Strange sea and c-quark parameters

• Charm fragmentation D(z, e) in Collins-Spiller
  parametrization

Experiments e
E531 0.169 0.036
NOMAD 0.165 0.035 / -0.026
E531 NOMAD 0.165 0.025

• Semileptonic branching ratio Bµ(E?) a/(1 b/E?)

Experiments a a b, GeV
E531 0.094 0.010 6.6 3.9 6.6 3.9
E531 NuTeV CCFR 0.086 0.006 4.1 2.5 4.1 2.5
E531 NOMAD 0.094 0.004 6.0 1.6 6.0 1.6
E531 NuTeV CCFR NOMAD 0.094 0.003 5.6 1.4 5.6 1.4
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Quark fragmentation measurement Scheme
F ED ? D E-1F

• Fp (Fee,
• Flp,Fln,Flp-,Fln-,
• F?p,F?n,F?p-,F?n-,F?p,F?n,F?p-,F?n-)
• Dp (Dd,Du,Ds,Dc,
• Mp,d,Mp,d-,Mp,u,Mp,u-,Mp,d,Mp,d-,Mp,u,Mp,u-
  ,Mp,s-)
• F, E, D ( z,pT s x,Q2 )

NOMAD
Durham HepData http//hepdata.cedar.ac.uk/
(more than 100 experimental DATA)
This work in progress
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Current JINR activity at CERN

• More precise knowledge of the Strange sea of the
  Nucleon allows to make more accurate prediction
  of strange particles production in pp collisions
  (ATLAS, CMS, ALICE)
• Measurement of fragmentation functions Dq and
  Mp,q provides better estimation of spin transfer
  from quark to produced particles (COMPASS)
• Improvement of neutrino-induced charm dimuon
  production can reduce uncertainty of charm
  background prediction for ?µ ? ?t oscillation
  experiments approx. by a factor 2 (OPERA)

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Muon neutrino from Atmospheric charm
The Baikal experiment is interesting in
prediction for cross-sections of charm particle
production in atmospheric nuclear cascade with
generation of the muonic neutrino.
In collaboration with N.Budnev and
S.Sinegovsky from ISU and API (Irkutsk) we plan
to calculate neutrino flux prediction for
different zenith angles using parameterization of
the spectrum of primary cosmic rays in wide
energy interval (including knee'' region).
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Publications in 2011 and Acknowledgements

• O.Samoylov, R.Petti, PEPAN Lett., 2011, Vol.8, ?7
  (170) Pp.1252-1261
• A.Edemskaya, D.Naumov, O.Samoylov, PEPAN Lett.,
  2011, Vol.8, ?7 (170) Pp.1276-1281
• O.Samoylov, Proceedings of the PANIC-11 conf.,
  2011, MIT (Cambridge, USA)
• O.Samoylov, Proceedings of the AYSS11 conf.,
  2011, JINR (Dubna, Russia) Pp.114

Work has been done in collaboration with
R.Petti (USC) and D.Naumov (JINR), with
participation of M.Gonchar (JINR), A.Edemskaya
(ISU), S.Starikova (ISU). We are grateful to
V.Cavasinni, L.Camilleri, L.DiLella for
stimulating discussions of this work.
This work is partially supported by JINR
grant, CERN, RFBR grant, Russian Federal Targeted
Program Research and Research-Human Resources
for Innovating Russia.
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Nuclear effects (incoming analysis)

• Nuclear corrections are crucial in order to use
  ?(?) data
• in global QCD ?ts since all existing data
  on heavy targets
• Only direct measurement of nuclear e?ects in ?(?)
  SFs from
• ratio 20Ne/D in BEBC

BEBC Coll., ZPC 36 (1987) 337 PLB 232 (1989) 417.

• Our measurements of d2s/dxdy cross-section on
  Carbon and Iron
• R.Petti, M.Gonchar, O.Samoylov

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Precise measurement of Charm Dimuonproduction
cross-section in ?N interactionsand its various
applications

• Oleg Samoylov (DLNP) _at_ 111th Scientific Council,
  Feb. 16, 2012