1 / 29

Pions emerging from an Arbitrarily Disoriented Chiral Condensate.

Pions emerging from an Arbitrarily Disoriented Chiral Condensate. Chandrasekher Mukku Deptt. of Mathematics & Deptt. of Computer Science & Applications Panjab University Chandigarh, India. Collaborative and ongoing work with. Bindu Bambah: Phys Rev D70 (2004) 034001-(1-18).

celina
Download Presentation

Pions emerging from an Arbitrarily Disoriented Chiral Condensate.

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Pions emerging from an Arbitrarily Disoriented Chiral Condensate. Chandrasekher Mukku Deptt. of Mathematics & Deptt. of Computer Science & Applications Panjab University Chandigarh, India.

  2. Collaborative and ongoing work with • Bindu Bambah: • Phys Rev D70 (2004) 034001-(1-18). From QFT to the DCC. • Annals of Physics 314 (2004) 54-74. Isospin squeezed states, dcc & pion production: a dynamical group theoretic approach • And with • Bindu Bambah and Shiv Chaitanya.

  3. HEAVY ION COLLISIONS PRESENT TO US FOR THE FIRST TIME THE OPPORTUNITYTo see the Universe in a heavy ion collisionAnd the Big Bang in a QGP,Hold Pions in parts of our LabsAnd explain them in twenty minutes. With Apologies to William Blake

  4. QCD at high temperature • Quark – gluon plasma • Chiral symmetry restored • “Deconfinement” ( no linear heavy quark potential at large distances ) • Lattice simulations : both effects happen at the same temperature

  5. Important parameters • Chiral symmetry initially restored and later broken in expanding and cooling Plasma • Plasma expanding and cooling and field roll down into broken vacuum two competing time scales • Orientation of roll down creates domains • Domain size? • Squeezing provides signals • Later discuss anisotropic expansions of plasma.

  6. Modelling phase transitions in QCD • QCD admits spontaneous breaking of its approximateSU(2)XSU(2) chiral symmetry. • Spontaneous breaking of thisapproximate symmetry gives very small pion masses; in thelimit of exact chiral symmetry these particles would be massless Nambu bosons. • Sigma Model models the QCD phase transition well. • It respects the SU(2)XSU(2) chiral symmetry of QCD with twolight flavours of quark and contains a scalar field (sigma)that has the same chiral properties as the quark condensate. Thesigma field represents the order parameterfor the chiral phase transition. • The phase transition of thelinear sigma model (without quarks) therefore provides a good starting point.

  7. Chiral symmetry restoration at high temperature Low T SSB <φ>=φ0 ≠ 0 High T SYM <φ>=0 at high T : less order more symmetry examples: magnets, crystals

  8. DCC FORMATION Chiralorder parameter in a far from equilibrium situation in the case of a sudden quench, long wavelength modes enhanced.Gives "baked Alaska" situation and in this rapidlyexpanding plasma the configuration of the evolving pion field willlag behind the rapid expansion A region of DCC can be thought of as a cluster of Pions of near identical momentum around zero( coherently produced) with anomalously large amount of fluctuation of the neutral fraction In order to produce such a state in a quark gluon plasma, the hot plasma must evolve far from equilibrium and in particular it must reach an unstable configuration such that the long-wavelength pion are amplified exponentially when the system relaxes to the stable vacuum state. Thus questions of whether a DCC forms and it evolves cannot be addressed in the framework of equilibrium thermodynamics. Techniques for applying QCD directly to such situations do not exist at present. To explain these non-equilibrium phenomena, we need to restructure the theory of phase transitions to incorporate the micro structures (or states) instead of macro structures

  9. Traditional experimental signals for DCC

  10. NEW SIGNALS EASIER TO MEASURE??? • 1. Pion correlations • 2. Total pion multiplicity distributions. • 3. Momentum dependent two pion correlations • 4. Oscillations in pion multiplicity distributions • 5. Oscillations in two particle correlations.

  11. THEORETICAL QUESTIONS ABOUT DCC

  12. Complete theoretical analysis which forms a basis of these signals

  13. Situation can be more general leading to richer signals

  14. Hamiltonian

  15. Consider three scenarios of disorientation.

  16. Woods-Saxon potential with parameter allowing for transition from adiabatic to quench.

  17. The neutral and charged pion distribution for small squeezing (adiabatic limit)I without DCC: • The neutral and charged pion distribution for large squeezing (quenched limit) with DCC

  18. Pion pair correlation functions at zero relative momentum Dashed graph is for neutral pions and the continuous graph is for charged pions.

  19. Correlations From the Hamiltonian, There is an entanglement of the forward and backward pions. This entanglement provides us with correlations between the pionswith forward and backward momenta for both the charged and neutralsector, The forward momentum positively charged pions with thebackward momentum negatively charged pions and the backwardmomentum positively charged pions and the forward momentumnegatively charged pions. As the effect of DCC formation is that the difference is enhanced dramatically for the zero momentum limit. k->0

  20. Answers to questions posed at beginning

  21. Testing with WA98 Ref: M.M. Aggarwal et. al. Poster in lobby. Event Display 84 gammas 12 charged particles Ypos(cm) Xpos(cm) February 8-12 ICPAQGP 2005

More Related