Oleg Samoylov (JINR, Dubna) @ AYSS’12 conf., Feb. 6-11, 2012

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

Oleg Samoylov (JINR, Dubna) @ AYSS’12 conf., Feb. 6-11, 2012

Oleg Samoylov (JINR) 2Charm dimuons in NOMAD

Motivation of the Charm Dimuons

g

Charge current (CC) Neutral current (NC)

qu (ν) qd (ℓ)

W+ Z0

f f'

g / Cos θW

NuTeV analysis Sin2θW = 1 − MW

2/MZ2 = 0.2277 ± 0.0013 (stat.) ± 0.0009 (syst.)

Rν = σνNC / σν

CC = 0.3916 ± 0.0013 (SM 0.3950)

Rν = σνNC / σν

CC = 0.4050 ± 0.0027 (SM 0.4066)


Motivation of the Charm Dimuons

Ro

be

rto

Pe

tti

for

the

NO

MA

D

NuTeV


A direct probe of the Strange sea

Proton structure is defined by Parton Distribution Functions (PDF’s)of quarks q(x) and gluons g(x)

νµN → µ−µ+ X

νµs → µ−c → µ−µ+ X


Available charm dimuon data

νµN → µ−µ+ X ⇒ νµs → µ−c → µ−µ+ X

Experiment Pubication Charm dimuonsNeutrino 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


Neutrino induced charm dimuons

• ν-induced charm dimuon production

Dc = Σ fh Dch,

Bμ = Σ fh B (h → μ+ X),h = D0, D+, Ds

+, Λ+

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

|Vcs|2=0.95

|Vcs|2=0.05


NOMAD experiment at CERN SPS

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/p=3.5%, ε=95%4. Good calorimetry: for ECAL ∆E/E=3.2%/E[GeV], for FCAL and HCAL ∆E/E=104%/E[GeV]

NIM A 515 (2003) 800-828

NIM A 404 (1998) 96-128

Muon neutrino beam

Front Calorimeter (FCAL)

Drift Chambers (DCH)

1995-1998


Reconstruction of the dimuon events

Signature Stat. Eff., %

νμ CC 8 759 065 65.8

μ-μ+ 20 480 22.5

μ-μ- 7 150 22.5

Eν = Eµ− + Eµ+ + Ehad Event informationEν = 81.4 GeV

Eµ− = 32.6 GeV

Eµ+ = 19.0 GeV

Mµµ = 0.945 GeV

Q2 = 3.26 GeV2

W2 = 89.4 GeV2

Charm dimuon

Background

Charm dimuon exp. DATA and Bg. subtraction:


Relevance of the NOMAD dimuon data

νµN → µ−µ+ X ⇒ νµs → µ−c → µ−µ+ X

Experiment Pubication Charm dimuonsNeutrino 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 ν-induced charm dimuons• The neutrino energies closest to the charm production threshold


Charm dimuon X-section measurement

• Measure RATIO of cross-sections to reduce systematics

Rµµ ≡ σµµ /σcc N≃ µµ /Ncc (x); x = Eν , xBj , √s

• Require leading µ− and Q2 ≥ 1 GeV2

∫ σµµ φ dx dy dEν = 5.15 ± 0.05 × 10−3 νµ CC

• Total systematic uncertainty (17 different sources) ~ 2%

• Agreement with model calculation based upon global PDF fit with NuTeV+CCFR dimuon data only


Sensitivity to the Strange sea

• Add NOMAD σµµ /σcc to global PDF fit 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%


Strange sea and c-quark parameters

• Charm quark mass and strange sea supression factor

Experiments mc (mc), GeV κs

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


Strange sea and c-quark parameters

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

Experiments ε

E531 0.169 ±0.036

NOMAD 0.165 +0.035 / -0.026

E531 + NOMAD 0.165 ±0.025

• Semileptonic branching ratio Bµ(Eν) = a/(1 + b/Eν)

Experiments a b, GeV

E531 0.094 ±0.010 6.6 ±3.9

E531 + NuTeV + CCFR 0.086 ±0.006 4.1 ±2.5

E531 + NOMAD 0.094 ±0.004 6.0 ±1.6

E531 + NuTeV + CCFR + NOMAD 0.094 ±0.003 5.6 ±1.4


Quark fragmentation measurement Scheme

Fπ = (Fee±,

Fℓp+,Fℓn

+,Fℓp-,Fℓn

-,

Fνp+,Fνn

+,Fνp-,Fνn

-,Fνp+,Fνn

+,Fνp-,Fνn

-)

Dπ = (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 } )

F = ED D = E⇒ -1F

Durham HepData http://hepdata.cedar.ac.uk/ (more than 100 experimental DATA)

NOMAD

See talk by Svetlana Starikova

http://hepdata.cedar.ac.uk/


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)

• 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 νμ → ντ

oscillation experiments approx. by a factor 2 (OPERA)


Muon neutrino from Atmospheric charm

The Baikal experiment is interesting in prediction for cross-sections of charm particle productions 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).


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 AYSS’11 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, RF Targeted Program “Research and Research-Human Resources for Innovating Russia”.

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

Oleg Samoylov (JINR, Dubna) @ AYSS’12 conf., Feb. 6-11, 2012

Oleg Samoylov (JINR, Dubna) @ AYSS’12 conf., Feb. 6-11, 2012

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