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

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

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

Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/ Flavor Physics Template 1947 K 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

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

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

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

Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/ 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., PRD difference between muon- and tau-lepton number

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

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

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

Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/ New Physics Light Particle New Physics from Light Particle !? SM-assisted loop s  dZ ′ ; b  sZ ′ Fuyoto, WSH, Kohda, 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 

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

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

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

Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/ 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 CERN Kinematic exclusion: See Neither K L →    “Nothing to Nothing” (just γγ ) ― Veto Everything ! But: Cannot Veto WILPs. ( Weakly Int. Light Particle )

Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/ “ 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 … 100 hrs (2013) ~ E391a, but … Starting Now Discovery Starting “ Now ” ! KL → XKL → X

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

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

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

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

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

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

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

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

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

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

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

Z′ Light Z′, K L → π 0 νν, other George W.S. Hou (NTU) LIO, Lyon, 24/11/ 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, * * Private Communication with LHCb N.B. Talk by A. Mauri 7/23 on LHCb Dark Boson search in K *      probably more constraining