A very brief introduction to Electroweak Baryogenesis Graham

A very brief introduction to Electroweak Baryogenesis Graham White (Note: partially based on talk by Csaba Balazs and partially on my recent book) Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Outline The problem of cosmic matter-antimatter asymmetry. Necessary conditions to dynamically generate baryon asymmetry. Baryon number violation Thermal field theory Current status Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Baryogenesis: theory ingredients zero temperature quantum field theory effective potentials, anomalies, gauge invariance, B, C, CP violation, classical solutions, instantons, sphalerons, tunneling, symmetry breaking, collider phenomenology, Standard Model, supersymmetry, Grand Unified Theories, scale invariance, right handed neutrinos, see-saw mechanism… finite temperature quantum field theory temperature corrections to potentials, temperature dependent masses, CTP formalism … thermodynamics kinetic theory, theory of phase transitions (bubble nucleation, length of phase transition, wall thickness, wall velocity), diffusion, fluctuations, quantum transport … astro- and low energy physics observational constraints, electric dipole moments, … cosmology inflation, reheating, preheating, … … Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

The problem of matter-animatter asymmetry Schumann ar. Xiv: 1310. 5217 Even the baryon abundance is a mystery Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Cosmic anti-baryon abundance negligible; consistent with secondary production . Giesen et al. 1504. 04276 Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Cosmic baryon abundance • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

The problem of matter-animatter asymmetry • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Baryon asymmetry: initial condition? • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

The problem of matter-animatter asymmetry Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Necessary conditions for baryogenesis Some mechanism created a positive baryon number after inflation. How? Sakharov’s necessary conditions: Sakharov 1967 Ø baryon number violation Ø C and CP violation Ø departure from thermal equilibrium Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Baryogenesis mechanisms: mix and match B violation C&CPV equilibrium SM SM+ EW phase-transition SM RHN N decay SM+GUT GUT breaking SM+GUT Q-ball decay … … …

Baryogenesis mechanisms: mix and match B violation C&CPV equilibrium Electroweak baryogenesis Kuzmin, Rubakov, Shaposhnikov 1985 SM SM+ EW phase transition Leptogenesis Fukugita, Yanagida 1986 SM RHN N decay GUT scale baryogenesis Yoshimura 1978 GUT GUT breaking Affleck-Dine mechanism Affleck, Dine 1985 GUT Q-ball decay … … Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Sakharov conditions and EWBG in the SM B violation → Sphalerons (forth coming) C and CP violation → CKM matrix (clarified overleaf) Departure from equilibrium →Electroweak phase transition (fails in practice)

C and CP violation in the SM SM weak interactions violate P. Sphalerons in the SM convert P violation into C violation. SM fermion CKM mixing violates CP. Beyond SM: easy to find new sources new P violating interactions new CPV phases

Baryon number in the SM • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Baryon number in the SM Quick summary of what we have learnt so far 1. Classical symmetries sometimes don’t survive the process of quantization because of anomalies 2. Fortunately B+L is just such a symmetry due to triangle anomalies 3. Field configurations that violate B+L have interesting topology (non-zero CS number) 4. Field configurations that have interesting topology look like quasi particles 5. A B+L violating candidate is the instanton which looks like a lump in Euclidean space and a tunnelling process in real space 6. Such an instanton tunnels from one degenerate vacuum in the SM to another 7. The standard model ground state is periodic with a potential height whose energy we will call the sphaleron energy Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Baryon number in the SM • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Baryon number violation in the SM • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Baryon number in the SM • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Departure from equilibrium expansion of space Hubble rate is not enough to catalyze BG inflation can easily drive baryogenesis thermodynamic phase transition first order PTs are particularly suitable to drive BG decaying field many possibilities: moduli, inflaton, other scalar, BSM matter, … … Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Electroweak baryogenesis: minimal and testable • Morrissey, Ramsey-Mussolf 1206. 2942 Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Bubble nucleation … Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Electroweak baryogenesis First order electroweak phase transition via nucleating bubbles: Morrissey, Ramsey-Mussolf 1206. 2942 Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Off the wall mechanism Cohen, Kaplan, Nelson 1990 -95 •

Off the wall mechanism Via diffusion CP violating bubble wall induces asymmetry inside: Konstandin 1302. 6713 Inside sphalerons are vev. suppressed: symmetry preserved. Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Electroweak baryogenesis: minimal and testable Will give (very) brief summary of 1. closed time path formalism 2. The effective potential at finite T 3. Bubble nucleation Morrissey, Ramsey-Mussolf 1206. 2942 Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Strength of electroweak phase transition • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

False vacuum decay Two questions: 1. how does vacuum decay occur (the bounce) 2. When does it occur (the nucleation temperature) Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

False vacuum decay • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Experimental signatures 1. Electric dipole moments constrain scale of new CPV physics 2. Collider searches constrain new scalar degrees of freedom 3. Gravitational waves potentially will constrain (or confirm) scale of strongly first order phase transitions Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Electroweak baryogenesis in the SM is ruled out • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Electroweak baryogenesis in the MSSM is essentially ruled out • Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis

Conclusions Matter-antimatter asymmetry: . . fundamental, complex, open problem. Baryogenesis is one possible solution. . there are several strong contenders: leptogenesis, inflation, Affleck-Dine, GUT, … Several mechanisms of baryogenesis exist. . baryogenesis can be embedded in many models: SM, MSSM…; electroweak scenario is testable! All models need theory work and experimental input. . lack of obvious extension of the SM is a general problem; on the bright side: early Universe cosmology has . . to be a single, consistent theory, so there are many constraints on any baryogenesis models Based on IOP concise physics series: A pedagogical introduction to electroweak baryogenesis