Strongly interacting systems Sanjay K. Ghosh Bose Institute Kolkata

1. Strongly interacting systems Sanjay K. Ghosh Bose Institute Kolkata 4th Winter School on Astroparticle Physics, December 14-22, 2009, Darjeeling

3. Existence of quarks – experimental evidence • e-p scattering • For smaller energy transfer the scattering is elastic • For moderate energy transfer proton gets excited For Higher energies : Deep inelastic Scattering Can One estimate the energy Needed to probe proton??? Dimension – Atom 10-10 m proton – 1fm = 10-15m Now use Uncertainty principle

5. What are experimental/observational avenues to study strongly interacting systems???? • Relativistic Heavy ion collision • -A reactions • Compressed baryonic matter • Neutron Stars • Early Universe phase transition Bose Institute, February 9 2007

7.  If we try to pull the quarks apart then interaction between them increases  Confinement • If we bring the quarks nearer interaction between them decreases  Asymptotic freedom

9. Single Baryon

12. Two ions (travelling from the left and right sides of the picture toward the center) approach one another. The ions are flat, instead of their usual spherical shape, because they're going so fast. (99.95% the speed of light, almost 186,000 miles per second) Just after the collision, thousands more particles form as the area cools off. Each of these particles is a clue to what happened inside the collision zone The two ions collide, smashing into one another and then passing through each other. Some of the energy they had before the collision is transformed into intense heat and new particles. If conditions are right, the collision "melts" the protons and neutrons and, for a brief instant, liberates the quarks and gluons.

15. Discovery 1967 : An object emitting pulses in radio band every 1.34 sec. with uniform interval Lighthouse model : strong magnetic field + rapid rotation of star – charged particles accelerated along field lines – synchrotron radiation

19. Different mechanism in RNS • Non-gravitational mechanism • Gravitational mechanism Non-gravitational mechanism Rotationally powered Pulsars : radio pulsars Magnetar : slow spin NS associated with young supernova (8 sec. compared to Crab pulsar 33 millsec.) fast slow down rate Soft Gamma repeater Anomalous X-ray pulsar Rapidly decaying magnetic field heats the star – gamma ray emission Starquake due to magnetic stress in crust

20. Signal for Deconfinement (Glendenning ) For first order phase transition : Existence of twin star : stars with higher central density than allowed normally For isolated millisecond pulsars : Spin up if transition to more compressible phase Backbending : anomalous behaviour of moment of inertia

21. Gamma Ray Bursts (GRB) : Detected in 1960 by US military satellites Short lived gamma ray bursts of very high energy - Beamed flash One time event Energy ~ 1052 ergs Long duration GRB : 2 sec. to several minutes Short duration GRB : Few millisec. To 2 sec. Long GRB : Death of a massive star and birth of black hole Supernova SN2003dh (29 March 2003) beneath the fading glare of GRB Short GRB : Higher energy photons than long GRB, No association with supernova found (as yet)

22. If neutrinos are allowed to escape the change in energy is given by

24. Normally small energy deposition • The high gravity environment might enhance the deposition • Result of two effects • Path bending of neutrinos • Gravitational red shift • 10% energy deposit

25. Hadronic matter  Phase transition  Quark matter Strange Quark Matter (u,d & s )  Ground state of matter First idea : Bodmer (1971) Resurrected : Witten (1984) Stable quark matter : Conflict with experience ???? 2-flavour energy  3-flavour Lowering due to extra Fermi well Stable Quark Matter  3-flavour matter Stable SQM  significant amount s quarks For nuclei  high order of weak interaction to convert u & d to s

26. Strangeletsmaller lumps of strange quark mater SQM in bulk : charge neutrality with electrons For A  107 SQM size < compton wavelength of electron  Electrons are not localized nu = nd = ns  Net charge QSQM = 0 if ms = mu = md But ms > mu or md  QSQM > 0  small + ve charge

27. Model Calculations : 1. Shell Model : shell filling for quarks using MIT bag model 2. Liquid drop model : Coulomb correction, surface tension and curvature energy Stability of SQM & Strangelets: E/A < mn mn =939 MeV for free gas of neutrons = 930 MeV in gas of 56Fe For Bulk SQM : Stable relative to 56Fe B1/4 < 163 MeV Neutron gas B1/4 < 164 MeV

28. Strangelets : lumps of strange matter •  smaller lumps A=6,18,24,42 ……… can be stable • shell structure for B1/4 = 145 MeV, ms = 0-300 MeV

29. SQM & Strangelet Search : • SQM : • Early universe quark-hadron phase transition • Quark nugget  MACHO • 2. Compact stars (Core of Neutron Stars or Quark Stars) • Strangelets : • Heavy Ion Collision • Short time • Much smaller size A ~ 10-20 • Stability Problem ??? • 2. Cosmic Ray events : • Collision of Strange stars or other strange objects

30. Detection of strangelets  Propagation mechanism of strangelets  How far can it travel through atmosphere How does it interact with atmosphere ? Important observations  Stability of strange matter  Small positive charge  massive s quark  Z/A << 1

31. Our Model:  Collision of strangelets with atoms results in the absorption of neutrons  more bound  Initial mass is taken to be small to obtain final values comparable to observation larger flux in cosmic rays  Lower limit of initial speed should be fixed by the requirement of reaching the top of the atmosphere surmounting the geomagnetic barrier Cut off velocity for A = 42 of the order of 0.3 Cut off velocity for A = 64 of the order of 0.2

32. Effects to be considered: 1. Neutron absorption 2. Proton absorption 3. Ionization loss

33. The final values denoted by suffix l :

34. THANK YOU