Download Reevaluation of dark matter direct detection rate

最新結果 ～理論から～
Junji Hisano （Eken）
タウレプトンセンター報告会
2011/03/10
内容
• 暗黒物質の物理
1. 暗黒物質直接探索
• フレーバーの物理
1. 超対称模型におけるμ-e遷移過程
2. 真空の安定性からくる超対称模型における
tanβの上限
3. その他
暗黒物質直接探索
WIMP-nucleus elastic scattering
nucleus
WIMP
• Ions
• Heat
• Scintillation
• DM local density:
ρDM =~0.3GeV/c2/cm3
• Spherical isothermal halo:
vDM~vsun~230km/sec
Recoil energy ~vDM2 MT~O(10) keV.
• Interaction of WIMP and nucleus
Spin-independent (SI) and spin-dependent (SD)
Event rate is proportional to A3 (SI) or J(J+1) (SD)
Almost experiments are sensitive to SI interaction.
From ICEHP10 (Talk by Gascon)
CDMS-II have two signal and
EDELWEISS-II have four events in
signal region.
Expected BG=0.8
Expected BG<1.6
Evaluation of neutralino-nucleon interaction
Effective interaction of neutralino to light quarks/gluon:
(Drees & Nojiri)
Effective SI interaction of Neutralino to nucleon:
Evaluation of WIMP-nucleon interaction
Effective interaction of Neutralino to light quarks/gluon:
Matrix elements
From latest lattice results,
Effective SI interaction of Neutralino to nucleon:
Evaluation of WIMP-nucleon interaction
Effective interaction of Neutralino to light quarks/gluon:
Twist-2 operators for gluon and quarks
Matrix elements are given by parton-distribution func.
Effective SI interaction of Neutralino to nucleon:
Neutralino in MSSM
Effective interaction of Neutralino to light quarks/gluon:
• Higgs exchange
• squark exchange
q: light quarks (u,d,s)
Q:heavy quarks (c,b,t)
More precise evaluation of cross section
In diagram (b), dominant
contribution comes from quark
momentum around squark or
neutralino mass. On the other
hand, in (d), it is around quark
mass.
Here, cQ is higher order correction,
More precise evaluation of cross section
Effective neutralino-nucleon SI coupling (pure bino limit)
Twist-2
Gluon
In the MSSM, the SI cross section may be corrected up to O(10)%.
(JH, Ishiwata, and Nagata)
Electroweak-interacting massive particles
Dark matter particles have only electroweak gauge interactions.
Wino and Higgsino in SUSY SM are such examples. Elastic
scattering is induced by loop processes. The cross section is only
suppressed by weak gauge/Higgs boson masses, not DM mass.
q: light quarks (u,d,s)
Q:heavy quarks (c,b,t)
Electroweak-interacting massive particles
We evaluate all relevant diagrams and also correct mistakes in
previous calculations. We find that accidental cancellation
suppresses the cross sections, especially when Higgs mass is light.
(JH, Ishiwata, and Nagata)
(JH, Ishiwata, Nagata and Takesako in preparation)
Vector dark matter
Universal extra dimension (UED) models and Littlest Higgs model
with T parity predict that a vector particle, which is a partner of
photon in SM, is stable and dark matter candidate.
In UED models the Kaluza-Klein (KK) quark masses are degenerate
with KK photon, which is DM candidate. Then, the twist-two
operator contribution can dominate over other contributions.
SI cross section in UED
UED model (5D) predicts 10^-45 to10^-46 cm^2.
(JH, Ishiwata, Nagata and Yamanaka)
フレーバーの物理
超対称模型におけるμ-e遷移過程
SUSY Flavor Problem
Introduction of SUSY breaking leads to new flavor violation, which
induces leptonic and hadronic flavor-changing processes.
Slepton mass
matrix
lepton mass
matrix
SUSY breaking
When sleptons have off-diagonal terms in mass matrix,
Here,
18
LFV in decoupling case
When SUSY particle masses are larger than O(1-10) TeV, SUSY
contributions to flavor changing processes are suppressed below the
experimental bounds even if squark and slepton mixings are not small.
Even in this case, the Higgs exchange
contributes to LFV processes, since
SUSY SM has two doublet Higgs bosons.
LFV Higgs coupling is generated after
integrating SUSY particle at one-loop.
Tree
One-loop
μ→eγ
(Babu & Kolda)
μ-e conversion in nuclei
LFV in decoupling case
Ratio between Higgs exchange and SUSY 1 loop contributions in μ→eγ
SUSY 1 loop
Higgs exchange
(Hisano et al, 10)
Both contributions are almost proportional to tanβ in amplitude.
When SUSY/MA~(40-50), they are comparable.
LFV in decoupling case
Higgs exchange contribution v.s. SUSY 1 loop contribution
(JH, Yang, Sugiyama, Yamanaka)
μ-e conversion in nuclei and μ→eγ have different sensitivities
of mass spectrum and tanβ.
LFV in decoupling case
We may derive mass spectrum from ratio of branching ratios.
(Hisano et al, 10)
真空の安定性からくる超対称模型
におけるtanβの上限
Vacuum stability
tanβ(=vu/vd) is an important parameter in
SUSY phenomenology. When tanβ is quite
large, the charge breaking vacuum becomes
true vacuum since the off-diagonal term in
the stau mass matrix is large.
Here,
Stability of charge conserving vacuum
imposes upperbound on tanβ.
Acceptable metastable vacuum
If lifetime of the charge-conserving vacuum is longer than age of
the universe, the vacuum is acceptable. We estimate the
lifetime by evaluating the bounce solution numerically.
(JH and Sugiyama)
Upperbound on μ tanβ
Metastable condition
Global minimum condition
An application:
minimal gauge mediation
The minimal gauge mediation model predicts large tanβ, especially
when the messenger scale is low (~10^5GeV). Thus, the
metastability condition exclude a part of the parameter region
Prediction of
MGM.
Stau is tachyon.
Life longer than age of universe.
Charge-conserving
vacuum is Global min.
Stau mass >87.4GeV