Heavy flavor mesons in strong magnetic fields

Michal ŠumberaNuclear Physics Institute AS CR,

Řež/Prague

Based on the presentation of Peter Filip at CPOD 2013http://cpod2013.lbl.gov/scientific-program-1/scientific-talks/1130_Filip.pdf?attredirects=0&d=1and Particle production in strong electromagnetic fields in relativistic heavy-ion collisionsby Kirill Tuchin, arXiv:1301.0099 [hep-ph]

a

To probe the extended topologicalgluon field configurations, it isbeneficial to have a complementaryprobe - an external, coherentelectromagnetic field.

Because of the existence of quarkzero modes and associatedtopology, the magnetic field isideal. However, usually theavailable magnetic field is weak,leading to small corrections;but, not so if eB~Λ2

QCD - available in heavy ion collisions!

Why QCD in magnetic fields?B

Peak magnetic field ~ 1015 Tesla ! B Reaction plane

adapted from D. Kharzeev @ CPOD2013

Kharzeev, McLerran, Warringa,Nucl PhysA803(2008)227

Heavy ion collisions – source of the strongest magnetic

fields

Kharzeev, McLerran, Warringa,Nucl PhysA803(2008)227

Biot-Savarat law:

D. Kharzeev @ CPOD2013

Event-by-event generation of electromagnetic fields in heavy-ion collisions

Wei-Tian Deng and Xu-Guang Huang, Phys.Rev. C85 (2012) 044907

Direct calculations of Liénard-Wiechert potentials using coordinates and velocities of incoming protons* from HIJING

*Contributions from the produced partons to the generation of the EM field is neglected.

The electromagnetic fields at t = 0 and r = 0 as functions of the impact parameter bDue to EbyE fluctuations <|Ex|>≈<|Ex|>≈<|Bx|>≠0

Wei-Tian Deng and Xu-Guang Huang Phys.Rev. C85 (2012) 044907

For ax ~ ay ~ 3 fm and c2s ~1/3, we see from Eqs. (4.23)-(4.24) that for t

≤ 5 fm the magnetic fields decay inversely proportional to time.

However, if the produced matter, after a short early-stage evolution, is in the QGP phase, the electric conductivity σ is not negligible.

Magnetic field evolution in the presence of QGP medium I

Where ax and ay are parameters of Gaussian transverse entropy density profile:

Kirill Tuchin, arXiv:1301.0099 [hep-ph]

Due to finite electrical conductivity of QGP, magnetic field essentially freezes in the plasma

for as long as plasma exists!!!!!

Magnetic field evolution in the presence of QGP medium II

L. McLerran, V. Skokov arXiv:1305.0774 [hep-ph]

(May 3, 2013)

In contrast to the results obtained in Ref. [7], we showed that the effects of conductivity do not play an important role for realistic values.

Magnetic field for static medium with Ohmic conductivity, σOhm.

Magnetic field evolution in the presence of QGP medium III

Experimental signaturesof strong EM fields

in heavy ion collisions

ALICE & STAR charge separation result Chiral Magnetic Effect - if it exists - contributes to the reaction plane dependent two-particle correlator <cos( ϕα+φβ -2ΨRP)>, (α,β)=(±,±)

[ALICE Collaboration], Phys.Rev.Lett. 110 (2013) 012301

S. Voloshin @ CPOD2013

Alternative explanations

• conservation of transverse momentum • local charge conservation • due to the presence of elliptic flow many other

two-particle correlations enter all these corrections may be of the same order as the experimental signal experimentally disentangle the elliptic flow phenomenon from the creation of a strong magnetic field

A. Bzdak, V. Koch and J.Liao, Lect.Notes Phys.871, 503 (2013), arXiv:1207.7327 [nucl-th].

What other effects of strong EM fields are

availablein heavy ion collisions?

Adam Bzdak and Vladimir Skokov, Phys. Rev. Lett. 110, 192301 (2013), Anisotropy of photon production: Initial eccentricity or magnetic field

Recent measurements of the azimuthal anisotropy of direct photons in heavy-ion collisions at the energies of RHIC (A. Adare et al. [PHENIX Collaboration], Phys. Rev. Lett. 104, 132301 (2010)) show that it is of the same order as the hadronic one. This finding appears to contradict the expected dominance of photon production from a quark-gluon plasma at an early stage of a heavy-ion collision.

A possible explanation of the strong azimuthal anisotropy of the photons, given recently, is based on the presence of a large magnetic field in the early phase of a collision. In this letter, we propose a method to experimentally measure the degree to which a magnetic field in heavy-ion collisions is responsible for the observed anisotropy of photon production.

arXiv:1301.0099 [hep-ph]

Particle production in strong electromagnetic fields in relativistic heavy-ion collisions Kirill Tuchin1

1 Department of Physics and Astronomy, Iowa State University, Ames, IA 50011(Dated: January 21, 2013)

I review the origin and properties of electromagnetic fields produced in heavy ion collisions. The field strength immediately after a collision is proportional to the collision energy and reaches ~mπ

2 at RHIC and ~10~mπ2 at LHC

…

…Very strong electromag-netic field has an important impact on particle production. I discuss the problem of energyloss and polarization of fast fermions due to synchrotron radiation, consider photon decayinduced by magnetic field, elucidate J/ψ dissociation via Lorentz ionization mechanism andexamine electromagnetic radiation by plasma. I conclude that all processes in QGP areaffected by strong electromagnetic field and call for experimental investigation.

Broad range of phenomena

• Quarks and leptons are expected to be strongly polarized in plasma in the direction parallel or anti-parallel to the magnetic field depending on the sign of their electric charge. The synchrotron radiation alone is able to account for quenching of jets at LHC with pT as large as 20 GeV.

• Polarization of the final photon spectrum perpendicular to the field.

• At mid-rapidity the azimuthal asymmetry of the decay rate translates into asymmetric photon yield and contributes to the elliptic flow

• Finally, photon decay due to pair-production in external magnetic field leads to enhancement of dilepton yield.

• Magnetic field strongly modifies the azimuthal distribution of the produced J/ψ 's

Study dependence of quark jets , photons, dileptons and heavy quark mesons on ΨR

arXiv:1301.0099 [hep-ph]

Broad range of phenomena

Another work on heavy quarkoniaC.S. Machado et al.: Heavy quarkonium production in a strong magnetic field, arXiv:1305.3308 [hep-ph] (May 16, 2013)• Investigate the effects of a strong magnetic field on B and D mesons, focusing on

the changes of the energy levels and the masses of the bound states. • The field induces a mass reduction of hydrogen-like heavy bound states, an

effect which is mainly due to the coupling between the spin and the magnetic field. Using the Color Evaporation Model they discuss the possible changes in the production of J/ψ and Υ.

Differential J/ψ (left) and Υ (right) production cross section at √s = 4.5 TeV

arXiv:1301.0099 [hep-ph]

Particle production in strong electromagnetic elds in relativistic heavy-ion collisions Kirill Tuchin1

…

ggg

+ -

● Mixing in [B]:for B=0 c2 = s2 = 1/2

in [B] orto-Ps (J=1) and para-Ps (J=0) states {mz= 0} get Mixed together

● 30% of J/Ys affected in static B=1015 T

142ns

10ns

ggg

gg0.12ns

gg

P. Filip @ CPOD 2013

Positronium e e (1S, 2S ...)

ortho-ee (J=1, m =1,0,-1) and para-ee (J=0)

ortho-cc (J/Y m =1,0,-1) and para-cc (h )

Quarkonium and PositroniumJ/Y , (9460), f(1020): zero magnetic moments

● + -

z

lifetime: 142ns (3 ,5g g) 0.12ns (2 ,4g g)

● Bound state cc, bb (1S, 2S)

z c

● ct = 2100 fm (3 , ...g mm ) ct = 6.9 fm (2 , ...g rr )

color hyperfine -> DE =117 MeV

MAGNETIC QUENCHING

OF

ortho-Positronium DECAY

J/Y

P. Filip @ CPOD 2013

P. Filip @ CPOD 2013