Freeze-In of FIMP Dark Matter Karsten JEDAMZIK LPTA, Montpellier - PowerPoint PPT Presentation

Freeze-In of FIMP Dark Matter Karsten JEDAMZIK † † LPTA, Montpellier Firenze, 19th of May 2010 – p. 1

Outline of Talk I. Freeze-out of Weakly Interacting Massive Particles II. Freeze-In of Feebly Interacting Massive Particles Hall, K.J., March-Russell, West The Freeze-In Process Comparison to super-WIMPs A Unified View of Freeze-In and Freeze-Out Detectability Candidate Particles III. Conclusions on FIMPs IV. News of the Spite Plateau and the Lithium Problem V. Advertising IDM2010: ’Identification of Dark Matter’ 26.7.-30.7. in Montpellier Firenze, 19th of May 2010 – p. 2

Freeze-Out of Dark Matter need some dark matter particle X stabilizing symmetry (parity) X + ¯ annihilation reactions at X → standard model particles freeze out at some T< ∼ m X and n X ≪ T 3 Firenze, 19th of May 2010 – p. 3

Virtues of Freeze-Out Production of Dark Matter minimalistic assumptions as well as accelerator testability thermodynamic and chemical equilbrium at freeze-out seemingly reasonable assumption since typically t equ /t Hubble ≪ 1 � − 1 - required interactions in Ω h 2 ≈ 0 . 1 σv � 3 × 10 − 26 cm 3 s − 1 principle accelerator testable - in practice not that straightforward reminiscent to conditions which led to the standard Big Bang nucleosynthesis model Firenze, 19th of May 2010 – p. 4

The WIMP miracle it is known that due to apparent violation of unitarity of the SM new physics is required at the TeV scale a TeV-mass scale particle has σv ∼ 3 × 10 − 26 cm 3 s − 1 give/or take ∼ two orders of magnitude Firenze, 19th of May 2010 – p. 5

Question: Is freeze-out of dark matter the ONLY accelerator testable dark matter production mechanisim in thermodynamic equilibrium conditions ? No ! Firenze, 19th of May 2010 – p. 6

FIMP Dark Matter production per Hubble time imagine a particle X which is so feebly in- teracting with the plasma (in TE) that it will n B 1 Γ B 1 → B 2 + X t H ∆ n X /s ∼ never reach equilibrium abundance s g B 1 T 3 λ 2 m B 1 M pl /T 2 call it FIMP ≡ ∼ ”Feebly Interacting Massive Particle” gT 3 g B 1 λ 2 m B 1 M pl take interaction L ∼ λXB 1 B 2 with λ ≪ 1 ∼ where B 1 and B 2 are bath particles gT 2 the plasma produces it in attempting to attain equilibrium via B 1 → B 2 + X decay produc- prod. infrared dominated !!! tion g B 1 m X g λ 2 M pl → Ω X ∼ m B 1 Firenze, 19th of May 2010 – p. 7

Difference to super-WIMPs super-WIMPs as gravitinos or axinos are also very weakly interacting ∆ n G /s ∼ n 2 σvt H /s ∼ g 2 M pl Tσv reheat temperature essentially with σ ∼ 1 /M 2 pl for weak mass scale non-testable in accelerators – gravitino, for example requires detailed information of the inflaton sector → their production is ultraviolet dom- inated and reheat temperature T de- pendent difference between super-WIMPs and FIMPs is renormalizability of interaction Firenze, 19th of May 2010 – p. 8

Freeze-In of Dark Matter production reactions B 1 → X + B 2 become inefficient at T < ∼ m B 1 freezing-in (thawing-in) the dark matter abundance at n X ≪ T 3 production goes up with interaction strength Firenze, 19th of May 2010 – p. 9

Firenze, 19th of May 2010 – p. 10

Required Interaction Strength � 1 / 2 � � 3 / 4 � � 1 / 2 λ ≃ 1 . 5 × 10 − 12 � g ∗ ( m X ) m X 1 m B 1 10 2 g bath this is close to M EW /M GUT ∼ 10 − 13 g bath ≫ 1 possible Firenze, 19th of May 2010 – p. 11

A Unified View of Freeze-In and Freeze-Out L ∼ λXB 1 B 2 and M x ∼ M B 1 Region I: Coupling λ of X to thermal bath strong enough such that equilibrium ∼ T 3 density will be attained and at T < m X T 3 will be frozen out → non- n X ≪ relativistic freeze-out Region II: Coupling λ of X to thermal bath strong enough such that equilibrium ∼ T 3 density will be attained – however when T < m X no further reduc- tion → relativistic freeze-out Region III: Cou- pling to thermal bath NOT strong enough to attain equilibrium density ∼ T 3 – freeze-in – abundance of X dominated by freeze-in Re- gion IV: Coupling to thermal bath NOT strong freeze-in completes the lower half of the enough to attain equilibrium density ∼ T 3 diagram – freeze-in – abundance of X dominated by freeze-out of bath particles and subsequent decay Firenze, 19th of May 2010 – p. 12

A Unified View of Freeze-In and Freeze-Out L ∼ λXB 1 B 2 and M x ∼ M B 1 freeze-in completes the lower half of the diagram Firenze, 19th of May 2010 – p. 13

Another Phase Diagram L ∼ λXB 1 B 2 and M B 1 ∼ 1 TeV Firenze, 19th of May 2010 – p. 14

Detectability of FIMPs ? Production via B 1 → B 2 + X Ω X h 2 ≈ 1 . 09 × 10 27 g B 1 m X Γ B 1 √ m 2 g ρ g S B 1 ∗ ∗ τ B 1 = 7 . 7 × 10 − 3 sec � 3 / 2 � Ω X h 2 � − 1 � 2 � 10 2 � � 300 GeV m X � g B 1 100 GeV m B 1 g ∗ ( m B 1 ) 0 . 011 direct test of production mechanism in lab !!!!! Firenze, 19th of May 2010 – p. 15

Why not 2 → 2 Production dominant ? in case production via B 1 + B 2 → B 3 + X dominates, the Ω X - τ B correlation may be lost however, B 1 + B 2 → B 3 + X production dT ≈ 3 λ 2 T 2 m X K 1 ( m X /T ) dY X 128 π 5 SH is always phase space suppressed compared to B 1 → B 2 + X production λ 2 m 3 K 1 ( m B 1 /T ) dY X B 1 dT ≈ 16 π 3 SH Firenze, 19th of May 2010 – p. 16

Production of Dark Matter via Freeze-In of FIMPs so far, have assumed FIMP is the dark matter particle need some (at least approximate) symmetry which stabilizes the dark matter particle, call it parity the standard model particles have positive parity the dark matter particle and other yet undiscovered particles have negative parity, stabilizing them towards decay into standard model particles LOSP ≡ "Lightest Observable Sector Particle" which carries negative parity m LOSP < m FIMP is possible → the LOSP may be the dark matter particle FIMPs are produced by inverse decays, e.g. B + LOSP → FIMP , which decay into LOSPs after LOSP freeze-out the LOSP self-annihilation cross section can be large Firenze, 19th of May 2010 – p. 17

Four possibilities Firenze, 19th of May 2010 – p. 18

LOSP/FIMP Decays during BBN ? two-body decay: τ ∼ 10 − 2 sec (Ω X h 2 / 0 . 1) − 1 g B 1 for Ω X h 2 ∼ 0 . 1 and g B 1 ∼ 1 → no effect three-body decay: τ ∼ 3sec g − 2 (Ω X h 2 / 0 . 1) − 1 g B 1 possible effect, especially when Ω X h 2 < 0 . 1 and/or g B 1 ≫ 1 three-body decay, for example, when LOSP not directly coupled to FIMP Firenze, 19th of May 2010 – p. 19

Candidate Particles Moduli determining soft SUSY breaking parameters „ 1 + T « „ 1 + T « „ 1 + T « m 2 ( φ † φ + h † h ) h 2 φ 2 h µB Ay M M M „ 1 + T « „ 1 + T « „ 1 + T « ˜ h ˜ φ 2 h ∗ m ˜ g ˜ ˜ g µy µ h, g M M M Dirac Neutrinos within weak scale supersymmetry λ LNH u , λ ∼ 10 − 13 for observed neutrino masses !! Right-handed sneutrino close to perfect candidate for FIMP (cf. Asaka et al. 06,07) Firenze, 19th of May 2010 – p. 20

A CMS Experiment to find metastable particles consider FIMP is the dark matter in case, the LOSP is charged and/or strongly interacting, it may be stopped in the CMS detector (inner HCL region) decay of such stopped particles are easily seen in "beam-off" periods (only background cosmic rays) "sensitivity" to τ X ∼ 10 − 6 sec − 10 5 sec Firenze, 19th of May 2010 – p. 21

How to convince oneself that FIMPs constitute the dark matter ? the LOSP is charged and/or strongly interacting, NOT a neutralino it is metastable its life time falls is in the right ballpark to fulfill the τ LOSP > ∼ 10 − 2 sec m X /m LOSP relationship FIMPs as dark matter is a very plausible scenario how to really convince oneself one may determine m LOSP and m X ∼ m LOSP from kinematics the τ LOSP - Ω X relationship is consistent with/close to the WMAP value Firenze, 19th of May 2010 – p. 22

Summary dark matter production via freeze-out may occur in (plausible) thermodynamic equilibrium conditions, is UV insensitive, and accelerator testable ! when looking at other dark matter production mechanism with such attributes one is led to the process of freeze-in in fact, freeze-in and freeze-out may be unified in a dark matter interaction strength - mass diagram candidate particles for Feebly Interacting Massive Particles as required in ∼ 10 − 12 is suggestive freeze-in do exist, in fact, the required interaction strength λ< freeze-in production may lead to a simple testable correlation between the life time of a new fundamental metastable particle and the abundance of the dark matter Firenze, 19th of May 2010 – p. 23