Possible solution to the [sup 7]Li problem by the long lived stau

Jittoh, Toshifumi; Kohri, Kazunori; Koike, Masafumi; Sato, Joe; Shimomura, Takashi; Yamanaka, Masato

doi:10.1063/1.3131513

Cited by 8 publications

(60 citation statements)

References 32 publications

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“…In Ref. [36] the case of almost degenerate NLSP stausτ and LSP neutralinosχ has been considered. Here mass splittings smaller than δm = mτ − mχ < ∼ 1 GeV have been assumed.…”

Section: Bound-state Bbn and Prior Suggested Solutions To The 7 Lmentioning

confidence: 99%

CosmicLi6andLi7problems and BBN with long-lived charged massive particles

Jedamzik

2008

Phys. Rev. D

126

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Charged massive particles (CHAMPs), when present during the Big Bang nucleosynthesis (BBN) era, may significantly alter the synthesis of light elements when compared to a standard BBN scenario. This is due to the formation of bound states with nuclei. This paper presents a detailed numerical and analytical analysis of such CHAMP BBN. All reactions important for predicting lightelement yields are calculated within the Born approximation. Three priorly neglected effects are treated in detail:(a) photodestruction of bound states due to electromagnetic cascades induced by the CHAMP decay, (b) late-time efficient destruction/production of 2 H, 6 Li, and 7 Li due to reactions on charge Z = 1 nuclei bound to CHAMPs, and (c) CHAMP exchange between nuclei. Each of these effects may induce orders-of-magnitude changes in the final abundance yields. The study focusses on the impact of CHAMPs on a possible simultaneous solution of the 6 Li and 7 Li problems. It is shown that a priorly suggested simultaneous solution of the 6 Li and 7 Li problems for a relic decaying at τx ≈ 1000 sec is only very weakly dependent on the relic being neutral or charged, unless its hadronic branching ratio is B h ≪ 10 −4 very small. By use of a Monte-Carlo analysis it is shown that within CHAMP BBN the existence of further parameter space for a simultaneous solution of the 6 Li and 7 Li problem for long decay times τx > ∼ 10 6 sec seems possible but fairly unlikley.

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“…In Ref. [36] the case of almost degenerate NLSP stausτ and LSP neutralinosχ has been considered. Here mass splittings smaller than δm = mτ − mχ < ∼ 1 GeV have been assumed.…”

Section: Bound-state Bbn and Prior Suggested Solutions To The 7 Lmentioning

confidence: 99%

CosmicLi6andLi7problems and BBN with long-lived charged massive particles

Jedamzik

2008

Phys. Rev. D

126

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“…2 H + ( 4 He-X − ) → 6 Li +X − , with a cross section estimated orders of magnitude larger than that for the standard BBN 6 Li-synthesizing process. Initial estimates for this enhancemant factor were given at around 6 × 10 7 [2,7].…”

Section: Introductionmentioning

confidence: 99%

“…Other less important modifications, concerning constraints on CHAMPs, had also been considered [4,5,6]. Being of quadrupole (E2) nature the 2 H + 4 He reaction has a very small rate (S-factor: 10 −8 MeV barn) thus yielding typically very little 6 Li/ 1 H∼ 10 −14 in standard BBN. When the helium-nuclei is in a bound state ( 4 He-X − ) the above reaction may be replaced by its photonless analogue:…”

Section: Introductionmentioning

confidence: 99%

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Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

Jedamzik

2008

J. Cosmol. Astropart. Phys.

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The Big Bang nucleosynthesis (BBN) in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of 6 Li and 7 Li are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3 × 10 2 sec < ∼ τx < ∼ 10 12 sec. It is stressed that the production of 6 Li at early times T ∼ 10 keV is overestimated by a factor ∼ 10 when the approximation of the Saha equation for the 4 He bound state fraction is utilised. To obtain conservative limits on the abundance of CHAMPs, a Monte-Carlo analysis with ∼ 3 × 10 6 independent BBN runs, varying reaction rates of nineteen different reactions, is performed (see attached erratum, however). The analysis yields the surprising result that except for small areas in the particle parameter space conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in case the rates of a number of heretofore unconsidered reactions may be determined reliably in future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude. An ERRATUM gives limits on primordial CHAMP densities when the by Ref.[20] recently more accurately determined CHAMP reaction rates are employed.

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“…But the discussion in Q 2 < (1GeV) 2 is still uncertain. Also if the mass between CHAMPs and the decay product highly degenerate ∼ O(mπ) and the main decay mode happens through a coupling with a W-boson, new decay modes of bound states may have to be considered [16]. The destruction of 6 Li through this new decay mode can be important only if the capture of 6 Li process is efficient at T < 10 keV.…”

Section: With the Reheating Temperaturementioning

confidence: 99%

Extremely long-lived charged massive particles as a probe for reheating of the Universe

Takayama

2008

Phys. Rev. D

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We discuss the impact of charged massive particle big bang nucleosynthesis(CBBN) to explore the nature of the reheating of the Universe in the case that a new extremely long-lived charged massive particle(CHAMP) exists. If the mass of the CHAMP is within collider reach and it's lifetime is longer than 10 4 sec, the comparison between the CBBN prediction and observed 6 Li abundances may indicate nonstandard reheating in the early Universe without relying on details of the decay properties. Even if the CHAMP mass is outside the reach of colliders, the cosmological considerations may provide a nontrivial hint for the existence of such very heavy long-lived CHAMPs from the late Universe if the daughter particles are the dominant component of the present dark matter. We consider a low reheating temperature model as an example of the nonstandard reheating scenarios.

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Possible solution to the [sup 7]Li problem by the long lived stau

Cited by 8 publications

References 32 publications

CosmicLi6andLi7problems and BBN with long-lived charged massive particles

CosmicLi6andLi7problems and BBN with long-lived charged massive particles

Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

Extremely long-lived charged massive particles as a probe for reheating of the Universe

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