Georg-August-University Gttingen Laura Covi [ q,p ]= ih - PowerPoint PPT Presentation

Moriond EW 2019 - La Thuile, 19th March 2019 Baryon Asymmetry, DM & neutrino masses Georg-August-University Göttingen Φ Laura Covi [ q,p ]= ih Institute for Theoretical Physics Based on arXiv:1812.06122 [hep-ph] 
 with A. Biswas, S. Choubey and S. Khan GA No. H2020-MSCA-ITN-2015//674896 & No H2020-MSCA-RISE-2015//690575.

Outline Asymmetric Dark Matter: 
 general mechanism and properties Asymmetric DM: minimal model for 
 DM, neutrino masses, leptogenesis Co-genesis: 
 Baryogenesis and DM from RPV Outlook

Asymmetric 
 Dark Matter

Universe composition Why Ω DM h 2 ∼ 5 Ω B h 2 ?

Sakharov Conditions Sakharov studied already in 1967 the necessary conditions for generating a baryon asymmetry from a symmetric state: B violation: trivial condition since otherwise B remains zero... C and CP violation: otherwise matter and antimatter would still be annihilated/created at the same rate Departure from thermal equilibrium: the maximal entropy state is for B = 0, or for conserved CPT, no 
 B generated without time-arrow... Now exactly the same conditions have to hold also for the generation of a Dark Matter Asymmetry !

Asymmetric Dark Matter [Griest & Seckel ‘87, Kaplan, Luty &Zurek 90, ...] Assume instead that there is an asymmetry stored 
 in DM as in baryons: DM asymmetry generated in the same way as the baryon asymmetry.. It may also be generated together with the baryon asymmetry and then it is natural to expect the SAME asymmetry in both sectors. Ψ → B + X n DM ∼ n b → Ω DM ∼ 5 Ω b for m DM ∼ 5 m p = 5 GeV The puzzle of similar densities can be given by similar masses !

Asymmetric Dark Matter [Griest & Seckel ‘87, Kaplan, Luty &Zurek 90, … Falkowski, Rudermann & Volansky 2011] Simple mechanism to generate such case: out-of-equilibrium decay of a particle producing both B-L and DM, e.g. even decay of a RH neutrino Need similar CP violation in both sectors !

Asymmetric Dark Matter [Griest & Seckel ‘87, Kaplan, Luty &Zurek 90, ...] The simple picture can be extended m DM = 5 m p by taking into account the Boltzmann suppression factor at the time of creation of the asymmetry: DM Mass/ T_Decoupling

Asymmetric Dark Matter DM must annihilate sufficiently strongly to erase the symmetric DM component, so it may also interact more strongly than a WIMP with normal matter... Strong coupling... ...like baryons ! It may accumulate 
 in stars and change the star evolution...

A minimal model for asymmetric DM, neutrino masses and leptogenesis

A minimal ADM model [A. Biswas, S. Choubey, LC & S. Khan 2018] Let us consider a minimal model for leptogenesis with two RH neutrinos to explain the neutrino masses and give the correct mixing matrices, as well as leptogenesis. 
 The particle content of the model is given by We need an additional Dark SU(2) in order to annihilate 
 away the symmetric DM component and a discrete symmetry to reduce the number of possible couplings.

A minimal ADM model [A. Biswas, S. Choubey, LC & S. Khan 2018] The neutrino masses and mixings can be accommodated 
 with just two RH neutrinos: For the case of a pure imaginary second column we have: ( m ν ) ij = − v 2 v 2 y I iµ y I y ie y je + jµ 2 M 1 2 M 2 Real neutrino matrix in this limit ! Only a single Majorana phase (for 2 RH neutrinos !) survives at low energy !

Asymmetric Dark Matter The decay of the lightest RH neutrino generates at the same time an asymmetry in leptons and DM: ψη D Need similar CP violation in both sectors !

CP violation for ADM [A. Biswas, S. Choubey, LC & S. Khan 2018] The CP asymmetry in the decay has generally contributions from both lepton/DM sectors: ✏ ` ✏ D ✏ ` = ✏ D

CP violation for ADM [A. Biswas, S. Choubey, LC & S. Khan 2018] The CP asymmetry in the decay has generally contributions from both lepton/DM sectors: ✏ ` ✏ D But the wave-function contribution with virtual leptons/DM can dominate both asymmetries and give ! ✏ ` = ✏ D

CP violation for ADM [A. Biswas, S. Choubey, LC & S. Khan 2018] The CP asymmetry in both decays comes from the 
 same phases, contained in the neutrino sector, since the DM couplings can be chosen real: ⇥ 3((y † y) ∗ 12 ) 2 ⇤ Im ✏ ` = 1 + 2 ↵ 1 ↵ 2 Im [3(y † y) ∗ 12 ] ✏ D For one real and one imaginary columns of Yukawas, then (( y † y ) ∗ 12 ) 2 we have Real and exactly . ✏ ` = ✏ D α 1 α 2 > | ( y † y ) 12 ∗ | Similarly in case of we also obtain 
 practically equal CP violation in the decays.

A minimal ADM model [A. Biswas, S. Choubey, LC & S. Khan 2018] 1 Y N 1 Even if the CP ε D = 3.5×10 -7 , M DM = 0.76 GeV 10 −3 10 −9 parameters are the same, also ε l = 4×10 -7 10 −6 Y B (Red), Y D (Green) wash-out processes 10 −12 ε D = 3.5×10 -9 , M DM = 76 GeV 10 −9 play a role and Y N 1 naturally give a 10 −12 larger asymmetry 10 −15 in the DM sector 10 −15 than in the lepton 10 −18 10 −18 sector ! 0.1 1 10 100 M N 1 ) z (= T

A minimal ADM model [A. Biswas, S. Choubey, LC & S. Khan 2018] Generically need largish 
 ✏ ` in order to obtain the full baryon asymmetry. For the Dark Sector, also smaller values are OK if we tune the DM mass to compensate.

A minimal ADM model [A. Biswas, S. Choubey, LC & S. Khan 2018] For the Yukawa couplings of the neutrino sector, this means that the imaginary part of the couplings have to be large ! Indeed also pure imaginary coupling can satisfy all !

Neutrinoless decay ββ As in any model with only two RH neutrinos, one light neutrino mass eigenvalue vanishes and no full cancellation can happen in the effective mass: � � � � X gives m i U 2 m eff = � � 1 , 5 meV ≤ m eff ≤ 3 , 7 meV ei � � � � i for the case of normal hierarchy as 3 sin 4 θ 13 + m 2 2 cos 4 θ 13 sin 4 θ 12 + 2 m 3 m 2 sin 2 θ 13 cos 2 θ 13 sin 2 θ 12 cos(2 α + 2 δ CP ) m 2 eff = m 2 Minimal case of imaginary second column with δ CP = 0 , α = π / 2 m eff = | m 2 cos 2 θ 13 sin 2 θ 12 − m 3 sin 2 θ 13 | Minimal value for zero eigenvalue !

DD in the ADM model [A. Biswas, S. Choubey, LC & S. Khan 2018] ψ 1 ψ 1 h 1 , h 2 N N Due to the mixing of the scalars after EW symmetry breaking, the DM scatters with normal matter via intermediate Higgs and could be detected in DD (but beware of the cancellation!)

Co-genesis

Baryogenesis & SW DM [Arcadi, LC & Nardecchia 1312.5703] Generate both DM and baryon asymmetry from the decay of a mother particle. This is quite natural for the case of 
 gravitino DM (SuperWIMP mechanism!). The baryon and DM densities are naturally of comparable order due to the comparable CP violation and Branching Ratio respectively... Ω ∆ B = m p � ⇥ Ω τ →∞ � ⇧ → / ⇥ ⇥ CP BR B χ m χ Small numbers Ω DM = m DM BR ( ⇧ → DM + anything ) Ω τ →∞ χ m χ independent of m p � CP BR ( ⇥ → B / ) Ω ∆ B = Bino density m DM BR ( ⇥ → DM + anything) Ω DM Gravitino DM: BR is naturally small and DM stable enough !


 Gravitino DM in RPV SUSY [Arcadi, LC & Nardecchia 1507.05584] Moreover the large scalar mass suppresses the branching ratio into gravitinos too much... BR ( ˜ B → 3 / 2 + any) << ✏ CP Need a large gravitino mass to compensate & obtain , Ω DM ∼ 5 Ω B not so simple explanation after all..., but still possible m 3 / 2 < m ˜ with . g

Gluino NLSP in RPV SUSY [Arcadi, LC & Nardecchia 1507.05584] The gluino is in this scenario the lightest SUSY particle and may be produced at colliders; but it should be not too much lighter than the Bino, i.e. , g ∼ 0 . 1 − 0 . 4 m ˜ B ∼ 7 − 28 TeV m ˜ possibly in the reach of a 100 TeV collider. ✓ λ 00 ◆ � 2 ✓ ◆ 4 ⇣ m ˜ ⌘ � 5 m 0 g c τ ˜ g ∼ 1 , 5 cm 4 × 10 7 GeV 0 . 4 7 TeV The heavy squarks give displaced vertices for the gluino decay 
 via RPV, even for RPV coupling of order 1. 
 Gluino decay into gravitino DM is much too suppressed to be measured.

Conclusions & Outlook The baryon asymmetry of the Universe is jet an unsolved puzzle ! The basic ingredients for baryogenesis can be used also to generate a 
 DM asymmetry of a similar order. An imaginary column in the neutrino Yukawa is sufficient to generate the CP violation both for the lepton and Dark Matter asymmetry ! At low energy only a single Majorana phase survives in the simplest case, giving a low effective mass for neutrinoless double beta decay. For LHC: look at the extended scalar sector ?