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Oleg Teryaev BLTP, JINR. Chiral magnetic effect for heavy and strange quarks Physics at NICA ( iVth roundtable workshop) Dubna , JINR, September 9, 2009. Outline. Strange quarks as heavy ones: Vacuum and (multiscale) hadrons Axial anomaly and Heavy quarks polarization in nucleon

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Oleg teryaev bltp jinr

Oleg Teryaev


Chiral magnetic effect for heavy and strange quarksPhysics at NICA(iVth roundtable workshop)Dubna, JINR, September 9, 2009


  • Strange quarks as heavy ones: Vacuum and (multiscale) hadrons

  • Axial anomaly and Heavy quarks polarization in nucleon

  • Chiral magnetic effect for strangeness in Heavy Ions collisions

  • Transition to massless quarks

  • Local C, P and CP violation: signals in decays

  • Conclusions

Can s really be heavy
Can s REALLY be heavy?!

In nucleon (no valence “heavy” quarks) rather than in vacuum - may be considered heavy in comparison to small genuine higher twist – multiscale nucleon picture

In vacuum Strange quark mass close to matching scale of heavy and light quarks – relation between quark and gluon vacuum condensates (cancellation of classical and quantum symmetry breaking – for trace anomaly).

The same – for axial anomaly

Cancellation of explicit and anomalous symmetry breaking for massive quarks
Cancellation of explicit and anomalous symmetry breaking for Massive quarks

  • One way of calculation – finite limit of regulator fermion contribution (to TRIANGLE diagram) in the infinite mass limit

  • The same (up to a sign) as contribution of REAL quarks

  • For HEAVY quarks – cancellation!

  • Anomaly – violates classical symmetry for massless quarks but restores it for heavy quarks

Heavy quarks polarisation
Heavy quarks polarisation Massive quarks

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 (colour polarisability) f2 to g1

“Anomaly mediated” polarisation of heavy quarks

Numerics Massive quarks

Small (intrinsic) charm polarisation

Consider STRANGE as heavy! – CURRENT strange mass squared is ~100 times smaller – -5% - reasonable compatibility to the data! (But problem with DIS and SIDIS)

Current data on f2 – somewhat larger

Comparison gluon anomaly for massless and massive quarks
Comparison : Gluon Anomaly for massless and massive quarks Massive quarks

  • Mass independent

  • Massless (Efremov, OT ’88) – naturally (but NOT uniquely) interpreted as (on-shell) gluon circular polarization

  • Small gluon polarization – no anomaly?!

  • Massive quarks – acquire “anomaly polarization”

  • May be interpreted as a kind of circular polarization of OFF-SHELL (CS projection -> GI) gluons

  • Very small numerically

  • Small strange mass – partially compensates this smallness and leads to % effect

Charm strangeness universality
Charm/Strangeness universality Massive quarks

  • Universal behaviour of heavy quarks distributions - from non-local (C-even) operators

  • c(x)/s(x) = (ms /mc)2 ~ 0.01

  • Delta c(x)/Delta s(x)= (ms /mc)2 ~ 0.01

  • Delta c(x)/c(x) = Delta s(x)/s(x)

  • Experimental tests – comparison of strange/charmed hadrons asymmetries

Heavy unpolarized strangeness vector current
Heavy unpolarized Strangeness: vector current Massive quarks

  • Follows from Heisenberg-Euler effective lagrangian (confirmed: A. Moiseeva, M. Polyakov, Y. Silverding)

  • FFFF -> (Color = combinatoric) FGGG -> Describes strangeness contribution to nucleon magnetic moment and pion mean square radius

  • FFFF->FFGG -> perturbative description of chiral magnetic effect for heavy (strange) quarks in Heavy Ion collisions – induced current of strange quarks

Chiral magnetic effect for heavy strange quarks
Chiral magnetic effect for (heavy) strange quarks Massive quarks

  • Effective Lagrangian

  • Current and charge density from c-term

    (multiscale medium!)

  • Light quarks -> matching with D. Kharzeev et al’ -> correlation of density of electric charge with a gradient of topological one (Lattice ?)

Properties of perturbative charge separation
Properties of perturbative charge separation Massive quarks

  • Current carriers are obvious - strange quarks -> matching -> light quarks?

  • NO obvious relation to chirality – contribution to axial current starts from pentagon diagram

  • Effect for strange quarks is of the same order as for the light ones if topological charge is localized on the distances ~ 1/ms , strongly (4th power!) depends on the numerical factor

  • Universality of strange and charm quarks separation - charm separation suppressed as (ms /mc)4 ~ 0.0001 (But charm production is also suppressed – relative may be comparable at moderate energies – NICA?)

Other signals for local symmetry violations
Other signals for local symmetry violations? Massive quarks

  • Some other signals (CP-violating decays?? – question of V.I. Zakharov)

  • Topological charge: P-Violated, C-conserved; not sufficient for forbidden K decays

  • Other possibility – C - violating decays due to chemical potential

Forbidden decays in vacuum allowed in medium
Forbidden decays in vacuum – allowed in medium Massive quarks

  • C-violation -> (Weldon ’92)

  • (OT’96; Radzhabov, Volkov, Yudichev ’05,06 - NJL)

  • However: Short time of medium existence – EM part should be outside!)

Relating forbidden and allowed decays
Relating forbidden and allowed decays Massive quarks

  • In the case of complete mass degeneracy (OT’05, unpublished):

  • Tests and corrections – Bannikov,OT, in progress

Conclusions Massive quarks

  • Strange quarks may be considered as heavy sometimes

  • Chiral magnetic effect for stange quarks – straightforward modification of Heisenberg-Euler lagrangian

  • Strange-light transition; strange mass against topological charge correlation length

  • Multiscale hadron/medium

  • Local C-violation in medium – decays forbidden in vacuum with predictable ratios