Electroweak Baryogenesis A Status Report

Transcription

1 Electroweak Baryogenesis A Status Report Thomas Konstandin Odense, August 19, 2013 review: arxiv:

2 Outline Introduction SUSY Composite Higgs

3 Standard Cosmology time temperature

4 Standard Cosmology time temperature

5 Particle physics vs Cosmology Particle physics Cosmology Big Bang nucleosynthesis T ~ MeV electroweak scales T ~ 100 GeV?

6 Baryogenesis [Sakharov '69] Baryogenesis aims at explaining the observed asymmetry between matter and antimatter abundances. The main ingredients for viable baryogenesis are stated by the celebrated Sakharov conditions: Bnumber violation (baryonnumber) C and CP violation (charge/parity) outofequilibrium

7 Baryogenesis [Sakharov '69] Baryogenesis aims at explaining the observed asymmetry between matter and antimatter abundances. C and CP violation (charge/parity) outofequilibrium Bnumber violation (baryonnumber) The main ingredients for viable baryogenesis are stated by the celebrated Sakharov conditions:

8 Baryogenesis [Sakharov '69] Baryogenesis aims at explaining the observed asymmetry between matter and antimatter abundances. outofequilibrium C and CP violation (charge/parity) Bnumber violation (baryonnumber) The main ingredients for viable baryogenesis are stated by the celebrated Sakharov conditions:

9 Baryogenesis [Sakharov '69] Baryogenesis aims at explaining the observed asymmetry between matter and antimatter abundances. outofequilibrium C and CP violation (charge/parity) Bnumber violation (baryonnumber) The main ingredients for viable baryogenesis are stated by the celebrated Sakharov conditions:

10 Baryogenesis [Sakharov '69] Baryogenesis aims at explaining the observed asymmetry between matter and antimatter abundances. C and CP violation (charge/parity) outofequilibrium Bnumber violation (baryonnumber) The main ingredients for viable baryogenesis are stated by the celebrated Sakharov conditions:

11 Baryogenesis [Sakharov '69] Baryogenesis aims at explaining the observed asymmetry between matter and antimatter abundances. EW temp C B BL anomaly CP CKM matrix? eq electroweak phase transition?

12 eq Firstorder phase transition The free energy (as a function of the Higgs vev) decides the nature of the phase transition: secondorder crossover firstorder

13 eq Firstorder phase transitions Firstorder phase transitions proceed by bubble nucleations In case of the electroweak phase transition, the Higgs bubble wall separates the symmetric from the broken phase This is a violent process ( ) that drives the plasma outofequilibrium

14 Electroweak baryogenesis [Kuzmin, Rubakov, Shaposhnikov '85] [Cohen, Kaplan, Nelson '93] sphaleron (EW anomaly) B ion s u f f i d eq CP C

15 Electroweak baryogenesis [Kuzmin, Rubakov, Shaposhnikov '85] [Cohen, Kaplan, Nelson '93] CP ion s u f f i d

16 Electroweak baryogenesis [Kuzmin, Rubakov, Shaposhnikov '85] [Cohen, Kaplan, Nelson '93] B C CP ion s u f f i d

17 Electroweak baryogenesis [Kuzmin, Rubakov, Shaposhnikov '85] [Cohen, Kaplan, Nelson '93] B C CP e e ion s u f f i d

18 Electroweak baryogenesis [Kuzmin, Rubakov, Shaposhnikov '85] [Cohen, Kaplan, Nelson '93] B avoid washout: e CP e ion s u f f i d B

19 Baryogenesis [Sakharov '69] Baryogenesis aims at explaining the observed asymmetry between matter and antimatter abundances. EW temp C B BL anomaly CP Jarlskog invariant eq no EWPT beyond the SM physics essential

20 Hierarchy problem hierarchy problem This indicates that there is some kind of new physics around the corner that did not appear in collider experiments yet small hierarchy problem CP SUSY? (warped) extradimensions strong coupling / technicolor? eq

21 Why is this interesting? The hierarchy problem indicates that there is some BSM physics at EW scales Electroweak baryogenesis involves only physics at the electroweak scale that is accessible to collider experiments Electroweak baryogenesis leads naturally to the observed baryon asymmetry beyond SM?

22 What are the challenges? [Kuzmin, Rubakov, Shaposhnikov '85] [Cohen, Kaplan, Nelson '93] sphaleron (EW anomaly) B ion s u f f i d CP quantum mechanics statistical physics

23 Technical details

24 Semiclassical reflection Many particles change their mass when passing into the Higgs bubble wall frame and reflection when

25 Transport equations In case of a statistical system with particle distribution function the change in momentum and translates into or flow term force transport equation of Boltzmann type CP?

26 KadanoffBaym equations [Kadanoff, Baym '61] In order to quantify electroweak baryogenesis one needs a formalism that includes quantum effects (CP violation) as well as statistical effects (diffusion/transport) This is achieved by the KadanoffBaym equations that are a statistical generalisation of the SchwingerDyson equations of QFT (SchwingerKeldysh formalism) Formally the equation looks like SD, but The 2point function depends on x and y seperately X and p in Fourier (Wigner) space There is an additional 2x2 structure from the ininformalism

27 KadanoffBaym equations In Wigner space this leads to the Moyal star product With One of the Green functions (Wightman function) encodes the particle distribution function and is in equilibrium given by and in equilibrium

28 One fermion flavor For one fermion flavor with a spacetime dependent mass, the KadanoffBaym equation reads In order to do progress analytically, one typically uses several approximations/techniques: 1) Neglect most interactions: 2) Planar approximation (z): 3) Gradient expansion: [Kainulainen, Prokopec, Schmidt, Weinstock '02]

29 One fermion flavor For one fermion flavor with a spacetime dependent mass, an expansion in gradients leads to the equations And with forces CP [Cline, Joyce, Kainulainen '00] [Kainulainen, Prokopec, Schmidt, Weinstock '02] decays scatterings

30 Technical details

31 Ingredients 1 2 eq CP Strong first order electroweak phase transition Some fermion species that changes its mass in a CP violating way during the electroweak phase transition (and prefereable charged under )

32 Summary ion s u f f i d B CP B

33 Outline Introduction SUSY Composite Higgs

34 MSSM CP In the minimal supersymmetric standard model, the leading CP violation comes from the mass matrix of the charginos eq The strength of the electroweak phase transition is reduced by larger Higgs masses is enhanced by bosonic degrees of freedom that couple strongly to the Higgs stops important

35 CP Several flavours In the most prominent case (MSSM), CP violation results from mixing effects between different flavors. [Careno, Moreno, Quiros, Seco, Wagner '00] In this case, new CPviolating sources occur but also additional complications arise due to flavor oscillations gradient expansion? [TK, Prokopec, Schmidt '05]

36 MSSM In the minimal supersymmetric standard model, the leading CP violation comes from the mass matrix of the charginos Flavor mixing? Resonances? Higgs resummation? 1 08/11 05/05 04/12 02/08 00/06 Higgs transport? 10 00/01 Flavor oscillations? 100

37 MSSM Assuming a strong firstorder phase transition, the baryon assymetry depends mostly on the chargino mass and the CP violation in the chargino sector [TK, Prokopec, Schmidt, Seco '05]

38 EDMs Even if all sfermions are heavy, there are twoloop (BarrZee) contributions from the chargino to the EDM of the electron and the neutron [Chang, Chang, Keung '02]

39 EDMs Even if all sfermions are heavy, there are twoloop (BarrZee) contributions from the chargino to the EDM of the electron and the neutron 8.8% 7.5% 6.6% 5.8% 5.3% 4.7% 4.4% [Hudson et al. '11] 4.3% [Chang, Chang, Keung '02]

40 MSSM baryogenesis The EDM constraints translate into /11 05/05 04/12 02/08 00/06 00/01 Can EDM bounds be avoided by using Binos? [Li, Profumo, RamseyMusolf '08]

41 eq Phase transition MSSM phase transition after LEP: very heavy lefthanded stop required no color breaking [Carena, Nardini, Quiros, Wagner '08]

42 eq Phase transition no color breaking [Carena, Nardini, Quiros, Wagner '08] you are here! MSSM phase transition after LEP: very heavy lefthanded stop required

43 eq Phase transition However, in SUSY models with extended scalar sector, strong phase transitions are quite common. E.g. the nmssm is a singlet extension of the MSSM with the super potential And the resulting scalar potential ( A scalar potential of this form enough free parameters to lead to a strong firstorder phase transition in some part of the parameter space. )

44 Conclusions SUSY Electroweak baryogenesis in SUSY models cannot be ruled out, but with current experimental constraints it is a reather contrived scheme Light (< 200 GeV) and almost mass degenerate charginos (or Binos) CP violation that in the most optimistic cases is at the verge of beeing seen in EDM experiments (caveat: Binos?) Extended Higgs sector required for a strong firstorder phase transition

45 Outline Introduction SUSY Composite Higgs

46 Composite Higgs models The Higgs could be a PseudoGoldstone boson of a broken global symmetry QCD: The broken symmetry will determine the light degrees of freedom and their quantum numbers but also [Kaplan, Georgi '84]

47 Holographic techniques in composite Higgs models Lately, this old idea underwent a renaissance due to holographic models to determine some quantity of the strongly coupled theory (like the Higgs potential) in a 5D setup. [Contino, Nomura, Pomarol '03] [Agashe, Contino, Pomarol '04] 5D GIM mechanism for flavor problems oblique parameters better than in technicolor many parameters and a certain arbitrariness in the scalar sector

48 Ingredients Two ingredients of baryogenesis are missing in the Standard Model. These are provided in models that have an additional singlet in the low energy effective description eq Strong firstorder electroweak phase transition CP CP violation at dimensionfive

49 eq Phase transition The construction of a potential barrier and hence firstorder phase transitions are easily achieved in extended scalar sectors: For example consider deformations of the symmetric supermexicanhat that has a phase transition

50 CP CP violation During the phase transition this leads to a top mass of the form So, the complex phase during the phase transition behaves as Notice that the symmetry has to be broken for viable baryogenesis and the Higgs has to mix with the singlet.

51 Baryogenesis strength of CP violation strength of the phase transition [Espinosa, Gripaios, TK, Riva '11]

52 Signals Higgssinglet mixing ~ CP violation singlet mass [Espinosa, Gripaios, TK, Riva '11]

53 Conclusions composite Higgs Baryogenesis in composite Higgs models is generically possible if the sector of pseudogoldstone bosons is nonminimal. In the case of a scalar extension of the low energy theory, this leads to rich phenomenology traces of CP violation in terms of EDMs no (Higgssinglet mixing; singlet is not DM)

54 Conclusions Electroweak baryognesis is still a compelling framework to explain the observed baryon asymmetry. (minimal) SUSY models have been the prime contestants for solving the hierarchy problem in the last X years. Currently, alternatives like composite Higgs models or SUSY models with an extended scalar sector seem to gain momentum. Electroweak baryogenesis is a quite common feature of many of these models.