Spin physics with compass
This presentation is the property of its rightful owner.
Sponsored Links
1 / 31

Spin physics with COMPASS PowerPoint PPT Presentation


  • 78 Views
  • Uploaded on
  • Presentation posted in: General

Spin physics with COMPASS. G. K. Mallot CERN/PH for the COMPASSCollaboration. Savin Fest, Dubna, 7.12.2010. The starting point. Smallness of ΔΣ confirmed by SMC! Where, oh where is the proton spin?. Elliot Leader. small EMC, SMC. unknown in 1997. unknown.

Download Presentation

Spin physics with COMPASS

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Spin physics with compass

Spin physics with COMPASS

G. K. Mallot

CERN/PH

for the COMPASSCollaboration

Savin Fest, Dubna, 7.12.2010


The starting point

The starting point

Smallness of ΔΣ confirmed by SMC!

Where, oh where is the proton spin?

Elliot Leader

small

EMC, SMC

unknownin 1997

unknown

Savin Fest, Dubna, 7.12.2010


Theory input 1988

Theory Input 1988

PLB 206 (1988) 309

ZPC 41 (1988) 239

PLB 212 (1988) 391

Savin Fest, Dubna, 7.12.2010


Lepton photon 1989

Lepton-Photon 1989

G. Ross 1989

possible scenario:

∆G ≈ 6 (Q2=10 GeV2)

∆g/g(x) = 1 for xg > 0.1

still unresolved after SMC & SLAC

Savin Fest, Dubna, 7.12.2010


Compass

COMPASS

Roots:

in DIS (SMC, NMC, EMC) and spectroscopy (Wa89,WA102,xBarrel )

Goals:

gluon polarization, flavour distributions, spin transfer

meson spectroscopy, glue balls, polarisability

Savin Fest, Dubna, 7.12.2010


Compass1

COMPASS

Beam:160 GeV µ+, pol. 80%

from π decay

Two-stage spectrometer

60 m long

Hodoscopes

SM2

E/HCAL1

Muon Wall 2

MWPC

SM1

RICH1

E/HCAL2

Polarized Target

MWPC, Gems, Scifi,

W45 (not shown)

160 GeV

µ beam

Muon Wall 1, Rich Wall

Straws, Gems

Infrastructure

Micromegas, SDC, Scifi

Scifi, Silicon

Savin Fest, Dubna, 7.12.2010


June 1998

June 1998

COMPASS fully approved in October 1998

Savin Fest, Dubna, 7.12.2010


Hcal1 february 1999 2000

HCAL1: February 1999 - 2000

Savin Fest, Dubna, 7.12.2010


2001 hcal1 and muon wall 1

2001 HCAl1 and Muon Wall 1

Savin Fest, Dubna, 7.12.2010


Straws

Straws

Savin Fest, Dubna, 7.12.2010


Compass 2004

COMPASS 2004

Savin Fest, Dubna, 7.12.2010


Parton distribution functions

Parton Distribution Functions

Three twist-2 PDFs

unpolarised PDF

quark with momentumxPin a nucleon

well known – unpolarized DIS

q(x)

f1q (x)

helicity PDF

quark with spin parallel to the nucleon spinin a longitudinally polarised nucleon

known – polarized DIS

Dq(x)

g1q(x)

transversity PDF

quark with spin parallel to the nucleon spin in a transversely polarised nucleon

DTq(x)

h1q(x)

chiral odd, poorly known

Savin Fest, Dubna, 7.12.2010


Factorization x sect asymmetries

Factorization & x-sect. asymmetries

Semi-inclusive scattering

long. double spin asymmetry

transverse single asymmetry

Inclusive scattering

Savin Fest, Dubna, 7.12.2010


Compass target system

COMPASS Target system

solenoid 2.5T

dipole magnet 0.5T

acceptance ± 180 mrad

3He – 4He dilution

refrigerator (T~50mK)

6LiD/NH3

50/90% pol.

40/16% dil. f.

μ

Savin Fest, Dubna, 7.12.2010


Helicity structure

Helicity structure

Savin Fest, Dubna, 7.12.2010


Proton asymmetries

Proton asymmetries

incl.

π+

K+

π–

K−

  • incl. & semi-incl. asymmetries,

  • similar data for deuteron

Savin Fest, Dubna, 7.12.2010


Q 2 evolution of g 1 x q 2

Q2 evolution of g1(x,Q2)

p

d

CLAS

HERMES

  • Q2dependence of g1 data related to gluon polarization (DGLAP)

  • Limited kinematic range (c.f. unpol. HERA)

Savin Fest, Dubna, 7.12.2010


The role of quark flavours

The role of quark flavours

LO semi-inclusive data analysis

Savin Fest, Dubna, 7.12.2010


Longitudinal spin transfer to

Longitudinal spin transfer to  & 

2003/2004 data 69500 Λ

41600 Λ

Λ

Λ

  • Large (!) DLL for Λrelated to antistrange quark distribution

JINR, Dubna, June 21, 2010


Bjorken sum rule

Bjorken sum rule

from neutron β decay

Savin Fest, Dubna, 7.12.2010


Spin physics with compass

Gluon polarization from PGF (LO)

Data not yet in global fits

Savin Fest, Dubna, 7.12.2010


Transverse spin structure

Transverse spin structure

Savin Fest, Dubna, 7.12.2010


Tmd parton distributions

TMD parton distributions

aka

Sivers

Transversity

Boer–

Mulders

  • 8 intrinsic transverse-momentum dependent PDFs at LO

  • Azimuthal asymmetries with different angular modulations in the hadron and spin azimuthal angles, Φh and Φs

Savin Fest, Dubna, 7.12.2010


Proton collins asymmetry

Proton Collins asymmetry

p

Fit to COMPASS d, HERMES, BELLE (Collins FF, e+e-)

in good agreement with new proton data

Savin Fest, Dubna, 7.12.2010


Proton sivers asymmetry

Proton Sivers asymmetry

h+

h−

  • compatible with zero for the deuteron

  • non-zero asymmetry for pos. hadrons

Savin Fest, Dubna, 7.12.2010


What s next compass ii

What’s next: COMPASS-II

  • PolarisedDrell-Yan

  • Generalized Parton Distributions (GPD)

  • Pion (and kaon) Polarisabilities

recommended by Programme Committee (SPSC)

Savin Fest, Dubna, 7.12.2010


Pion polarisability experimental situation

Pion Polarisabilityexperimental situation

 - 

Planned measure-ment better thanχPT-prediction.

Strong JINR parti-cipation


Spin physics with compass

PDF, GPD, TMD

PDF GPD TMD

Ji, PRL 2003, Belitsky, Ji, Yuan PRD 2004

Meissner, Metz, Schlegel, JHEP 0908:056 2009

Savin Fest, Dubna, 7.12.2010


Generalized parton distribution functions

Generalized Parton Distribution Functions

~

~

  • Novel concept, universal, H, H, E, E

  • H (E) nucleon helicity (non)conservation

  • Nucleon form factors and PDFs as limiting cases

  • Correlating transverse spatial and longitudinal momentum degrees of freedom (‘tomography’)

  • DVCS & DVMP

Total orbital momentum:

x is not x-Bjorken

X.-D. Ji, Phys. Rev. Lett. 78 (1997) 610

Savin Fest, Dubna, 7.12.2010


Gpds need ecal0

GPDs need ECAL0

  • ECAL0 essential for GPD programme

  • led by JINR, promising novel technology MAPDs

  • looking forward for another decade of fruitful collaboration with JINR & Igor

Savin Fest, Dubna, 7.12.2010


Eor 2001

EoR 2001

Savin Fest, Dubna, 7.12.2010


  • Login