Oleg teryaev jinr dubna
This presentation is the property of its rightful owner.
Sponsored Links
1 / 14

Strange Quarks Polarisation from Gluon Anomaly IWHSS-08, Torino, COMPASS Week, March 31 2008 PowerPoint PPT Presentation


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

Oleg Teryaev JINR, Dubna. Strange Quarks Polarisation from Gluon Anomaly IWHSS-08, Torino, COMPASS Week, March 31 2008. Outline. Small gluon polarisation – where is an axial anomaly (c.f. talk of E. Leader)? Strange quarks as heavy quarks in vacuum and inside the nucleon

Download Presentation

Strange Quarks Polarisation from Gluon Anomaly IWHSS-08, Torino, COMPASS Week, March 31 2008

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


Oleg teryaev jinr dubna

Oleg Teryaev

JINR, Dubna

Strange Quarks Polarisation from Gluon AnomalyIWHSS-08, Torino, COMPASS Week, March 31 2008


Outline

Outline

Small gluon polarisation – where is an axial anomaly (c.f. talk of E. Leader)?

Strange quarks as heavy quarks in vacuum and inside the nucleon

Strange sea polarisation and higher twist : scale and SIGN

Heavy strange quarks transversity

Conclusions: Hidden connections in nucleon spin puzzle !?


Strange quarks polarisation from gluon anomaly iwhss 08 torino compass week march 31 2008

Gluon anomaly and its manifestations

  • Small gluon polarisation – does it mean that anomaly contribution disappeared

  • Not necessary! – also in quarks

  • EXACT relation (holds for each flavour separately)

  • Light quarks – non-, heavy - conservation


Heavy quarks polarisation

Heavy quarks polarisation

Non-complete cancellation of mass and anomaly terms (97)

Gluons correlation with nucleon spin – twist 4 operator NOT directly related to twist 2 gluons helicity BUT related by QCD EOM to singlet twist 4 correction f2 to g1


Numerics

Numerics

Small (intrinsic) charm polarisation

Consider STRANGE as heavy! – 100 times larger – reasonable compatibility to the data

Current data on f2 – appr 50% larger


Can s really be heavy

Can s REALLY be heavy?!

Strange quark mass close to matching scale of heavy and light quarks – relation between quark and gluon vacuum condensates (similar cancellation of classical and quantum symmetry violation – now for trace anomal). BUT - common belief that strange quark cannot be considered heavy,

In nucleon rather than in vacuum - may be considered heavy in comparison to small genuine higher twist – multiscale nucleon picture


Sign of polarisation

Sign of polarisation

Anomaly – constant and OPPOSITE to mass term

Partial cancellation – OPPOSITE to mass term

Naturally requires all “heavy” quarks average polarisation to be negative IF heavy quark in (perturbative) heavy hadron is polarised positively


Heavy strangeness transversity

Heavy Strangeness transversity

Heavy strange quarks – neglect genuine higher twist: 0 =

Strange transversity - of the same sign as helicity and enhanced by M/m!


Conclusions

Conclusions

Anomaly is more alive...

Strange quarks INSIDE nucleons may be treated as heavy ones

Extra relations between seemingly independent quantities of different twist (both accessible by COMPASS).May be non-unique: c.f. d2 relation to Sivers function

Hidden connections in N spin structure


Sum rules ii

Sum rules -II

To simplify – low moments

Especially simple – if only gluonic pole kept:


Compatibility of ssa and dis

Compatibility of SSA and DIS

  • Extractions of Sivers function: – “mirror” u and d

  • First moment of EGMMS = 0.0072 (0.0042 – 0.014)

  • Twist -3 - similar for neutron and proton (0.005) and of the same sign – nothing like mirror picture seen –but supported by colour ordering!

  • Current status: Scale of Sivers function – seems to be reasonable, but flavor dependence differs qualitatively.

  • Inclusion of pp data, global analysis including gluonic (=Sivers) and fermionic poles


Relation of sivers function to gpds

Relation of Sivers function to GPDs

Qualitatively similar to Anomalous Magnetic Moment (Brodsky et al)

Quantification : weighted TM moment of Sivers PROPORTIONAL to GPD E (hep-ph/0612205 ):

Burkardt SR for Sivers functions is now related to Ji SR for E and, in turn, to Equivalence Principle


Sivers function and extended equivalence principle

Sivers function and Extended Equivalence principle

Second moment of E – zero SEPARATELY for quarks and gluons –only in QCD beyond PT (OT, 2001) - supported by lattice simulations etc.. ->

Gluon Sivers function is small! (COMPASS, STAR, Brodsky&Gardner)

BUT: gluon orbital momentum is NOT small: total – about 1/2, if small spin – large (longitudinal) orbital momentum

Gluon Sivers function should result from twist 3 correlator of 3 gluons: remains to be proved!


Generalization of equivalence principle

Generalization of Equivalence principle

Various arguments: AGM 0 separately for quarks and gluons – most clear from the lattice (LHPC/SESAM, confirmed recently)


  • Login