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Introduction 2 Higgs had been discovered !! 2012/07/04 All - PowerPoint PPT Presentation

The MSM Neutrino masses, Dark Matter, and Baryon Asymmetry Takehiko Asaka (Niigata Univ.) @Toyama Univ. (2014/01/12) Introduction 2 Higgs had been discovered !! 2012/07/04 All elementary particles in the Standard Model had been


  1. The  MSM Neutrino masses, Dark Matter, and Baryon Asymmetry Takehiko Asaka (Niigata Univ.) @Toyama Univ. (2014/01/12)

  2. Introduction 2  Higgs had been discovered !! 2012/07/04  All elementary particles in the Standard Model had been confirmed by experiments !! Takehiko Asaka (Niigata Univ.) 12/01/2014

  3. 3 Whatʼs next after Higgs discovery? Takehiko Asaka (Niigata Univ.) 12/01/2014

  4. Prologue: Physics beyond the SM 4  About 20 years ago …,  There was no “convincing” evidence for physics beyond the minimal standard model (SM)  People looked for physics beyond the SM “mainly” based on theoretical arguments and curiosities:  Hierarchy problem  Gravity, String, …  Strong CP problem  Why 3 generations?  Why anomalies cancel?  … Takehiko Asaka (Niigata Univ.) 12/01/2014

  5. News from the sky 5 Neutrino Oscillations Cosmic Microwave Background (CMB [SuperK] [WMAP] Takehiko Asaka (Niigata Univ.) 12/01/2014

  6. Physics beyond the MSM 6  In the last decade(s), we have collected quite “convincing” evidences for physics beyond the MSM  Neutrino oscillations  Baryon asymmetry  Dark matter  Dark energy  Primordial density perturbations Takehiko Asaka (Niigata Univ.) 12/01/2014

  7. Physics beyond the MSM 7  In the last decade(s), we have collected quite “convincing” evidences for physics beyond the MSM  Neutrino oscillations  Baryon asymmetry  Dark matter  Dark energy ?? ??  Primordial density perturbations  Today, I would like to explain the  MSM, which can solve first three problems! Takehiko Asaka (Niigata Univ.) 12/01/2014

  8. Origin of neutrino masses 8  Neutrino mass scales �  Atmospheric: �� ��� ≃ 2.4 � 10 �� eV � �  Solar: �� ��� ≃ 7.5 � 10 �� eV � ⇒ Need for physics beyond the SM !  Important questions:  “What is the origin of neutrino masses?”  “How do we test it experimentally?” Takehiko Asaka (Niigata Univ.) 12/01/2014

  9. Standard Model 9 Higgs Quarks and Leptons Gauge Bosons Bosons (left-handed) (right-handed)       u c t u c t R R R       �       d s b d s b R R R L L L �           e e R R R                  e L L L Takehiko Asaka (Niigata Univ.) 12/01/2014

  10. Standard Model 10 Higgs Quarks and Leptons Gauge Bosons Bosons (left-handed) (right-handed)       u c t u c t R R R       �       d s b d s b R R R L L L �           e e R R R                  e L L L Takehiko Asaka (Niigata Univ.) 12/01/2014

  11. Neutrino Minimal SM (  MSM) 11 TA, Blanchet, Shappshnikov (ʻ05), TA, Shaposhnikov (ʻ05) Higgs Quarks and Leptons Gauge Bosons Bosons (left-handed) (right-handed)       u c t u c t R R R       �       d s b d s b R R R L L L �           e e R R R                �� ��   �� e L L L Takehiko Asaka (Niigata Univ.) 12/01/2014

  12. Extension by RH neutrinos 12 Minkowski ʼ77 M              c M L i F L + h.c. Yanagida ʼ79  R R R R R 2 Gell-Mann, Ramond, Slansky ʻ79 Glashow ʻ79  Seesaw mechanism ( � � � � Φ ≪ � � )           c c 0 M M 0 1 1          D c L c         L ( , ) h c . ( , N ) h c . . 1 L R  T        M M   0 M  T 2 2 N M M M D M M R D D M M  T U M U diag m m m ( , , )  1 2 3  Light, active neutrinos → explain neutrino oscillations Where is  Heavy, neutral leptons �� ≃ � � � the scale  Mass � � of mass?  Mixing Θ � � � /� � mixing in CC current � Takehiko Asaka (Niigata Univ.) 12/01/2014

  13. Scale of Majorana mass 13  The simplest case: one pair of � � and � � 1      2 T 2 M M M F M M /   D D M M M 2  F F Neutrino Yukawa Coupling t 0    2 -2 M m atm -4 log 10 (F)  F F e -6 -8 -10 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 log 10 (M M /GeV) Majorana Mass Takehiko Asaka (Niigata Univ.) 12/01/2014

  14. Convenstional seesaw scenario: 14  Neutrino Yukawa couplings are comparable to those of quarks and charged leptons  M R >> 100GeV  Explain smallness of neutrino masses via seesaw [Yanagida; Gell-Mann, Ramond, Slansky]  Decays of RH neutrino(s) can account for baryon asymmetry through leptogenesis [Fukugita, Yanagida]  Physics of RH neutrino cannot be tested directly by experiments Takehiko Asaka (Niigata Univ.) 12/01/2014

  15. Scale of Majorana mass 15  The simplest case: one pair of � � and � � 1      2 T 2 M M M F M M /   D D M M Baryogenesis M 2 via leptogenesis  F F Neutrino Yukawa Coupling t Fukugita, Yanagida ʻ86 0 -2 -4 log 10 (F)  F F e -6 -8 -10 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 log 10 (M M /GeV) Majorana Mass Takehiko Asaka (Niigata Univ.) 12/01/2014

  16. The  MSM: [TA, Blanchet, Shaposhnikov; 16 TA, Shposhnikov]  No new mass scale is introduced  M R ~<100GeV  Lightest RH neutrino (~keV) can be DM (?) [Dodelson, Widrow,…]  Oscillation of RH neutrinos can account for baryon asymmetry of the universe [Akhmedov, Rubakov, Smirnov/ TA, Shaposhnikov]  Physics of RH neutrinos can potentially tested by experiments Takehiko Asaka (Niigata Univ.) 12/01/2014

  17. Scale of Majorana mass 17  The simplest case: one pair of � � and � � 1      2 T 2 M M M F M M /   D D M M Baryogenesis M 2 via leptogenesis  F F Neutrino Yukawa Coupling t Fukugita, Yanagida ʻ86 0 -2 -4 log 10 (F)  F F e -6 Baryogenesis -8 via neutrino osc. -10 Akhmedov, Rubakov, Smirnov ʻ98 -12 TA, Shaposhnikov ʻ05 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 log 10 (M M /GeV) Majorana Mass Takehiko Asaka (Niigata Univ.) 12/01/2014

  18. Roles of three HNL 18 (“Dark” sterile neutrino) N 1  Dark Matter Candidate (Here, we do not specify its detail.)  To avoid constraints, Yukawaʼs should be suppressed   essentially, F 0 1 N and N (“Bright” and “Clear” sterile neutrinos) 2 3  Neutrino Oscillation data LINK  Masses and mixings  Baryon Asymmetry of the Universe (BAU)  Mechanism via sterile neutrino oscillation Takehiko Asaka (Niigata Univ.) 12/01/2014

  19. 19 §2 Dark matter in the  MSM Dark Matter Candidate: lightest heavy neutral lepton N1 with ~keV mass Dodelson, Widrow / Shi, Fuller / Dolgov, Hansen / Abazajian, Fuller, Patel /… (Incomplete list) Takehiko Asaka (Niigata Univ.) 12/01/2014

  20. Decays of DM 20  N1 is not completely stable particle !  Dominant decay: for � � ~ keV �  Lifetime can be very long � 10 �� � � � � 5 � 10 �� sec keV + … Θ � � �  N1 is not completely dark !  Subdominant decay: � + …  Branching ratio is small �� � 27� �� /8�  But, severely restricted from X-ray observations Takehiko Asaka (Niigata Univ.) 12/01/2014

  21. Production of DM 21  Due to smallness of Yukawa couplings, N1 is not thermalized in the early universe  Production scenarios:  Dodelson-Widrow scenario  Production via active-sterile neutrino mixing   W,Z N1 �/� � �  Dominant production at � � 100MeV ���  Shi-Fuller scenario  Production is boosted in the presence of lepton asymmetry due to the MSW effect Takehiko Asaka (Niigata Univ.) 12/01/2014

  22. Cosmological Constraints 22  Radiative decays of DM  No signal  Upper bound on mixing angle !  Light heavy neutral lepton = WDM � �� ~Mpc keV � � Erase structures on smaller scales! � � � �  Lower bound on mass (Ly-  forest observations)  � � ≳ 8 keV (DW scenario) Boyarsky, Lesgourgues, Ruchayskiy, Viel ʼ09,ʼ09  Phase-space analysis (Tremaine-Gunn bound)  � � ≳ 1 � 2 keV Tremaine, Gunn ʻ79 Boyarsky, Ruchayskiy, Iakubovskyi ʻ08 Gorbunov, Khmelnitsky, Ruvakov ʻ08 Takehiko Asaka (Niigata Univ.) 12/01/2014

  23. Dark Matter 23 Laine, Shaposhnikov ʻ08 Takehiko Asaka (Niigata Univ.) 12/01/2014

  24. Dark Matter 24  Dodelson-Widrow mechanism does not work by Ly-  constraint  Shi-Fuller mechanism ??  Entropy production??  Yukawa couplings of N1 are very suppressed  N1 decouples from the seesaw mechanism -> Lightest active neutrino � � � � 10 �� eV  N1 contribution is negligible for baryogenesis  N2 and N3 are responsible for  Seesaw mass matrix for neutrino masses  Baryon asymmetry of the universe Takehiko Asaka (Niigata Univ.) 12/01/2014

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