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) annihilation reactions at X + ¯ X → standard model particles freeze out at some T< ∼mX and nX ≪ 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 tequ/tHubble ≪ 1

Ωh2 ≈ 0.1

• σv

3×10−26cm3s−1

−1 - required interactions in 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 × 10−26cm3s−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

imagine a particle X which is so feebly in- teracting with the plasma (in TE) that it will never reach equilibrium abundance call it FIMP ≡

”Feebly Interacting Massive Particle”

take interaction L ∼ λXB1B2 with λ ≪ 1 where B1 and B2 are bath particles the plasma produces it in attempting to attain equilibrium via B1 → B2 + X decay produc- tion

production per Hubble time

∆nX/s ∼ nB1ΓB1→B2+XtH s ∼ gB1T 3λ2mB1Mpl/T 2 gT 3 ∼ gB1λ2mB1Mpl gT 2

• prod. infrared dominated !!!

→ ΩX ∼

gB1 g λ2Mpl mX mB1

Firenze, 19th of May 2010 – p. 7

Difference to super-WIMPs

super-WIMPs as gravitinos or

axinos are also very weakly

interacting ∆nG/s ∼ n2σvtH/s ∼ g2MplTσv with σ ∼ 1/M 2

pl for weak mass scale

gravitino, for example → their production is ultraviolet dom- inated and reheat temperature T de- pendent

reheat temperature essentially non-testable in accelerators –

requires detailed information of the inflaton sector

difference between super-WIMPs and FIMPs is renormalizability of interaction

Firenze, 19th of May 2010 – p. 8

Freeze-In of Dark Matter

production reactions B1 → X + B2 become inefficient at T < ∼ mB1 freezing-in (thawing-in) the dark matter abundance at nX ≪ 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 λ ≃ 1.5 × 10−12

mX mB1

1/2

g∗(mX) 102

3/4

1 gbath

1/2

this is close to MEW/MGUT ∼ 10−13

gbath ≫ 1 possible

Firenze, 19th of May 2010 – p. 11

A Unified View of Freeze-In and Freeze-Out L ∼ λXB1B2 and Mx ∼ MB1

freeze-in completes the lower half of the diagram Region I: Coupling λ of X to thermal bath strong enough such that equilibrium ∼ T 3 density will be attained and at T < mX nX ≪ T 3 will be frozen out → non- relativistic freeze-out Region II: Coupling λ

• f X to thermal bath strong enough such that

equilibrium ∼ T 3 density will be attained – however when T < mX 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 enough to attain equilibrium density ∼ T 3 – 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 ∼ λXB1B2 and Mx ∼ MB1

freeze-in completes the lower half of the diagram

Firenze, 19th of May 2010 – p. 13

Another Phase Diagram L ∼ λXB1B2 and MB1 ∼ 1 TeV

Firenze, 19th of May 2010 – p. 14

Detectability of FIMPs ?

Production via B1 → B2 + X

ΩXh2 ≈ 1.09×1027gB1

gS

∗

√

gρ

∗

mXΓB1 m2

B1

τB1 = 7.7 × 10−3sec gB1

• mX

100 GeV 300 GeV mB1 2 102 g∗(mB1) 3/2 ΩXh2 0.011 −1

direct test of production mechanism in lab !!!!!

Firenze, 19th of May 2010 – p. 15

Why not 2 → 2 Production dominant ?

in case production via B1 + B2 → B3 + X dominates, the ΩX-τB correlation may be lost however, B1 + B2 → B3 + X production

dYX dT ≈ 3λ2T 2mX 128π5 K1(mX/T) SH

is always phase space suppressed compared to

B1 → B2 + X production

dYX dT ≈ λ2m3

B1

16π3 K1(mB1/T) 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 mLOSP < mFIMP 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 (ΩXh2/0.1)−1gB1 for ΩXh2 ∼ 0.1 and gB1 ∼ 1 → no effect three-body decay: τ ∼ 3sec g−2 (ΩXh2/0.1)−1gB1 possible effect, especially when ΩXh2 < 0.1 and/or gB1 ≫ 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

m2 „ 1 + T M « (φ†φ + h†h) µB „ 1 + T M « h2 Ay „ 1 + T M « φ2h m˜

g

„ 1 + T M « ˜ g˜ g µy „ 1 + T M « φ2h∗ µ „ 1 + T M « ˜ h˜ h,

Dirac Neutrinos within weak scale supersymmetry

λ LNHu,

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 τX ∼ 10−6sec − 105sec

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 τLOSP> ∼10−2sec mX/mLOSP relationship

FIMPs as dark matter is a very plausible scenario how to really convince oneself

• ne may determine mLOSP and mX ∼ mLOSP from kinematics

the τLOSP-ΩX 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 freeze-in do exist, in fact, the required interaction strength λ< ∼10−12 is suggestive 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