1. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 1 A Very Light Z′ for Muon g ‒ 2 and Its Implications 24 Nov @ LIO/Flav-Compo-DM, IPNL, Lyon

2. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 2 Fuyoto, WSH, Kohda, 1412.4397 (PRL’15), and to appear

3. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 3 I.Frontiers of Flavour Physics t c h0h0 ► ► Z0Z0 Z′Z′

4. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 4 Flavor Physics Template 1947 K 1950 1960 1970 1980 1990 2000 2010 2020 CPV DCPV TCPV B  DCPV Nobel B s →  t t → cZ/cH (    bound) ~ 20 yrs “   ” ? ? ?! Top Redemption: * Poor up-type limits  Unsuppressed CKM * Uniquely Heavy 50 years

5. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 5 “ Blind man blessed by senses. ” Grossman-Nir Limit @ J-PARC but... KOTO @ 100 hrs (2013) ~ E391a, but... mostly S h a k e I t O f f !

6. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 6 taken from Goldouzian, Top2014 … such as warped extra dimensions. Our limit can be translated into a constraint on the KK gluon to be heavier than 1.1 TeV [9]. Agashe, Perez, 07 Soni, PRD’07 Azatov, Panico, Perez, Soreq, JHEP2014 Top Compositeness t → cZ   Also, ATLAS 1508.05796

7. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 7 3.7  Not Good, Not Bad … Not Too Good … C. Langenbruch @ Moriond EW 3 fb −1 NP? Δ C 9 ~ −1: Z′ heavy Z′ e.g. 1307.5683; 1308.1501; 1310.2478; 1310.3877; 1310.1082; 1311.6729 … B → K *    

8. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 8 Pick up t → cZ' topic at LHCP2014 I ask from back of room: “How to Search?”. Came the reply: “  or  ” mode. X.G. He et al., PRD1991 1403.1269 difference between muon- and tau-lepton number

9. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 9 “unconstrained” Q, D, U: vector-like quarks with Z′ charge “ gauged L  – L  ” FuyutoWSHKohda Our Original Interest

10. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 10 constraints II. Very Light Z ′ : t → cZ′ w/ constraints

11. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 11 gauged L  – L  Altmannshofer, Gori, Pospelov, Yavin [PRD  PRL] Neutrino Trident Production “ Neutrino Trident Production ” Quite Weakly Coupled New Physics Light Particle New Physics from Light Particle !? “LBNE” but not DM 1406.2332

12. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 12 New Physics Light Particle New Physics from Light Particle !? SM-assisted loop s  dZ ′ ; b  sZ ′ Fuyoto, WSH, Kohda, 1412.4397 Tune away by Z 2 flow of U(1)′ charge Q, D, U : vector-like quarks with Z′ charge 〈ϕ〉 : generates Z′ mass gauged L  – L 

13. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 13 A Little Some Work … … … … Aim: allowed t → cZ′ rate K (B)  (K ( * ) )… But,

14. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 14 III. Kaon: the Oldest Frontier K  →    vs K L →    Grossman-Nir Bound possible KOTO surprise and more … 68+ Fixation 1997 S h a k e I t O f f ! mostly

15. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 15 stable blinding spot Bound on K →  X  1/200 weaker than K  →   bound bound much weaker

16. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 16 K  →   “   ” Loophole  vs K L →   X  The KOTO Expt at J-PARC can discover above the Grossman-Nir Bound ! KL → XKL → X A Surprise ! “Trivial” “ Blind man Blessed by Senses. ” See Not Window basically Same as E787/949 @ BNL @ CERN Kinematic exclusion: See Neither K L →    “Nothing to Nothing” (just γγ ) ― Veto Everything ! But: Cannot Veto WILPs. ( Weakly Int. Light Particle )

17. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 17 “ Blind man blessed by senses. ” @ J-PARC mostly Shake It Off ! discovery The KOTO Expt at J-PARC can discover above the Grossman-Nir Bound ! KL → XKL → X Grossman-Nir Limit 3/8 but … KOTO @ 100 hrs (2013) ~ E391a, but … Starting Now Discovery Starting “ Now ” ! KL → XKL → X

18. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 18 Violation of Grossman-Nir Bound, but not quite, and possible implications Fuyoto, WSH, Kohda, PRL 5/2015 But our Z′ is existence proof

19. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 19 IV. Where Else? ― an Illustration Circumstantial Hints/Possibilities in Rare B & K Decays

20. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 20 BaBar’13 (471M BB(bar)) BaBar: mild hint in B + → K + N.B. B(B → K   ) << B(K →   ) Fuyoto, WSH, Kohda, 1412.4397 10 bins driven by lowest bin Belle needs to follow up with this Binned m mis analysis. (  Belle II)

21. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 21 285 MeV300260 “ excess ” Range of “ excess ” “ excess ” in 1 st bin Can be refined by NA62 Can be refined by NA62 The 2 nd Window table in backup Fuyoto, WSH, Kohda, PRL ’ 15 OUTDATED BY LHCb DB

22. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 22 Comment: Light “ g-2 ” Z’ decay is prompt, even when highly boosted.

23. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 23 LHCb 1508.04094 [ PRL’15 supplementary ]

24. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 24 The 2 nd Window White frame as in FHK PRL, red dashed is with LHCb DB

25. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 25 Y Uc & Y Ut reasonable strength? μμ Perhaps 100 TeV SPPC/FCChh Needed.... Or not? [50% μμ ] Fuyoto, WSH, Kohda, PRL’15 and to appear Opportunity θCθC

26. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 26 Monotop ? X Z’ Agram et al., 1311.6478 Our typical number −6 for “ a ” is 10 −6 |Y ut Y ct |

27. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 27 V. Conclusion K L → π 0 + nothing: can occur above Grossman-Nir Bound  KOTO ! If See Early Event(s), Try Hard to Kill... But not Overly So. If above GN Bound, then likely “π 0 ” mass object. When KOTO reaches below GN Bound, concept still effective.  KOTO/NA62/LHCb/Belle(II) all in game (but LHCb takes lead?). Run, KOTO, Run ! (that slips thru NA62) N.B. Pursue also t → cZ' Have > 2 mo. Data at Hand !

28. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 28

29. Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/2015 29 LHCb 3 fb , JHEP 1406 Low q 2 Spike Search in B         * LHCb should do the “ extra work ”* for lowest q 2 Fuyoto, WSH, Kohda, 1412.4397 * * Private Communication with LHCb N.B. Talk by A. Mauri 7/23 on LHCb Dark Boson search in K *      probably more constraining