1 / 22

Neda Sadooghi Department of Physics Sharif University of Technology Tehran-Iran

QED at Finite Temperature and Constant Magnetic Field: 1. The Standard Model of Electroweak Interaction at Finite Temperature and Strong Magnetic Field. Neda Sadooghi Department of Physics Sharif University of Technology Tehran-Iran Prepared for CEP seminar, Tehran, May 2008. Introduction.

gates
Download Presentation

Neda Sadooghi Department of Physics Sharif University of Technology Tehran-Iran

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. QED at Finite Temperature and Constant Magnetic Field:1. The Standard Model of Electroweak Interaction at Finite Temperature and Strong Magnetic Field Neda Sadooghi Department of Physics Sharif University of Technology Tehran-Iran Prepared for CEP seminar, Tehran, May 2008

  2. Introduction The connection between • Particle Physics • Cosmology • Particle physics tests its predictions about matter genesis in the framework of cosmology • Cosmology can use the predictions of particle physics in order to cure unsolved problems in the theories concerned with the evolution of the universe

  3. The Problem of Baryogenesis Timeline of Big Bang • The very early universe • The Planck epoch • The grand unification epoch • The electroweak epoch • The inflationary epoch • Reheating • Bayogenesis • The early universe • …

  4. Elementary particle physics • Fermions • Quarks and Leptons (elementary particles) • Quarks: Q = u,d,s,b,c,t + antiquarks • Leptons: L= electron, muon, tau + neutrinos and antiparticles • Hadrons (composites) • Baryons: QQQ Proton (uud), Neutron (udd), Lambda hyperon (uds) • Mesons: QQ-bar , Kaon, ccbar • Bosons • Gauge bosons

  5. The problem of BaryogenesisFor a review see: hep-ph/9707419, hep-ph/0609145 1. Why the density of baryons is much less than the density of photons? • Observation: from CMB data • Theory: 2. Why in the observable part of the universe, the density of baryons is many orders greater than the density of antibaryons?

  6. The Problem of Baryogenesis • In a baryo-symmetric universe the number density of baryons would be 9 orders of magnitude smaller than what is observed in reality. Consequence: • Then, in the world would not be enough building material for formation of celestial bodies and life would not be possible.

  7. Sakharov Conditions (1967) For baryogenesis, 3 conditions are necessary: • C and CP violation • Non-conservation of baryonic charge • Deviation from thermal equilibrium in the early universe

  8. Different Mechanisms for Baryogenesis • Baryogenesis in massive particle decays • Electroweak baryogenesis • Affleck-Dine scenario of baryogenesis in SUSY • Spontaneous baryogenesis • Baryogenesis through leptogenesis • Baryogenesis in black hole evaporation • Baryogenesis by topological defects Domain walls, cosmic strings, magnetic monopoles, textures • Electroweak baryogenesis in a constant magnetic field

  9. Electroweak Baryogenesis • Checking the Sakharov’s conditions: • C and CP violation • In the EWSM there are processes that violated C and CP • Baryon non-conservation: • The baryon number is violated via quantum chiral anomalies. C and CP violation are necessary to induce the overproduction of baryons compared to antibaryons • EWSM at finite temperature: • 2nd order phase transition at Tc = 225 GeV one-loop approx • 1st order phase transition at Tc = 140.42 GeV ring diagrams

  10. Baryon number non-conservation in EWSM • Periodic potential in EW gauge field • Each minima corresponds to a topological winding number • Transition from one vacuum to another can proceed • either by tunneling. This is very suppressed at T=0 • or over the barrier in a thermal system at high T • The top of the barrier corresponds to an unstable, static solution of the field equations called sphaleron, with E = 8-14 GeV • It can be shown that

  11. Electroweak phase transition at finite T • Theoretically it is possible to determine the effective potential at one-loop order, leading to a Tc = 225 GeV • This is a 2nd order phase transition • Potentials are calculated at T = 0, 175, 225, 275 GeV (from bottom to top)

  12. Electroweak phase transition at finite T • Considering the contribution of ring diagrams to the effective potential, a 1st order phase transition arises • For Higgs mass = 120 GeV and top mass = 175 GeV  the critical temperature is decreased to 140.42 GeV

  13. Result • Although the minimal EWSM has all the necessary ingredients for successful baryogenesis, • neither the amount of CP violation whithin the minimal SM, • nor the strength of the EW phase transition isnot enough to generate sizable baryon number • Other methods …

  14. Different Mechanisms for Baryogenesis • Baryogenesis in massive particle decays • Electroweak baryogenesis • Affleck-Dine scenario of baryogenesis in SUSY • Spontaneous baryogenesis • Baryogenesis through leptogenesis • Baryogenesis in black hole evaporation • Baryogenesis by topological defects Domain walls, cosmic strings, magnetic monopoles, textures • Electroweak baryogenesis in a constant magnetic field

  15. Primordial magnetic fields • Observation: • Large scale magnetic fields observed in a number of galaxies • Note: A homogeneous magnetic field would spoil the universe isotropy, giving rise to a dipole anisotropy in the background radiation COBE: Large scale magnetic field of primordial origin

  16. Magnetogenesis • Necessary: • A small seed field which is exponentially amplified by the turbulent fluid motion • Problems: • Find a mechanism to generate a seed field • Cosmological (EW or QCD) phase transitions • Find a mechanism for amplifying the amplitude and the coherence scale of the magnetic seed field • Magnetohydrodynamics

  17. A possible scenario of magnetogenesis (EWPT)K. Enqvist; astro-ph/9707300, A. Ayala et al. hep-ph/0404033 In general magnetic field in the primordial neutral plasma can be produced by: • Local (axial) charge separation local current  magnetic field During EW 1st order PT  Out of equilibrium conditions  bubble nucleation • Net baryon number gradient charge separation • Instabilities in the fluid flow  magnetic seed field production • Turbulent flow near the bubbles walls  amplification + freezing of the seed field • The magnetic field produced is of order • Hydrodynamic turbulence magnetic field enhancement by several orders • Inflation  large coherence scale

  18. Magnetic field in the aftermath of EWPTT. Vachaspati, 0802.1553 (hep-ph) • Decay of EW sphaleron changes the baryon number and produces helical magnetic field • Use the relationship between the sphaleron, magnetic monopoles and EW strings (Nambu 1977, Vachaspati 1992, 2000) • A possible decay mechanism for two linked loops of EW Z-strings

  19. Decay Mechanism of Sphaleron Decay • Sphaleron may be thought as two linked loops of EW Z-strings • The Z-strings can break by the formation of magnetic monopoles and an electromagnetic magnetic field connects the monopole-anti-monopole pairs • The Z string can shrink and disappear leaving behind two linked loops of electromagnetic magnetic field

  20. Magnetic field production during the preheating at the electroweak scale:A. Gonzalez-Arroyo et al., 0712.4263 [hep-ph] and a series of papers since 2005 To recap: • Decay of EW sphaleron changes the baryon number and produces helical magnetic field • The helicity of the magnetic field is related to the number of baryons produced by the sphaleron decay (Cornwall 1997, Vachaspati 2001) • It is therefore interesting to study EW phase transition and baryogenesis in the presence of constant magnetic field

  21. Electroweak baryogenesis in strong hypermagnetic field Series of papers by: • Skalozub + Bordag (1998-2006) • Electroweak phase transition in a strong magnetic field • Effective action in one-loop + ring contributions • Higgs mass Result: • The phase transition is of 1st order for magnetic field • The baryogenesis condition is not satisfied

  22. Strong magnetic fields

More Related