1、,Meson LNV decays as a probe of neutrino masses and mixings in LR seesaw model,Guo-Zhu Ning（宁国柱）,Center for High Energy Physics, Peking University,Based on Feng, Ning, arXiv: 1308.XXXX hep-ph,Outline,1. Introduction and motivation,2. LR seesaw model,3. Analytical evaluation,4. Numerical results,5. C
2、onclusion,1. Introduction and motivation,SNO,KamLAND,SK,other atmospheric, solar, accelerator, and reactor neutrino experiments,Oscillation experiments,Neutrino have tiny mass and flavor violation,Fogli et al.(2012),Global fitting,Neutrino in SM,In SM, neutrino is massless :,(1) Gauge symmetry;,( 2)
3、 Renormalization;,(3) Minimal particle spectrum;,No RH neutrino, only one Higgs doublet,Possible corresponding ways to extend:,(1) Extension of gauge group: eg. SUSY, Grand Unification.,(3) Extension of particle spectrum: eg. Canonical Seesaw.,(2) Effective operator: eg. Weinberg operator.,Canonical
4、 Seesaw,Extension of SM particle spectrum :,Three possible ways for the realization of Weinberg operator at tree level.,Neutrino mass in Type I seesaw:,Comment :,(1) Heavy neutrino mass and heavy-light mxing are two important ingredients for testing seesaw;,heavy-light mixing:,(2) Seesaw scale is ir
5、relevant to any physics.,LR Seesaw model,Gauge group,Advantage:,A TeV scale LR seesaw represents an attractive class of seesaw models that can be experimentally tested.,Current constraints (I): Low energy processes,LFV,CP observables,Meson LNV decays have not considered under the framework of LR see
6、saw model.,Majorana neutrino：,Lepton number violation,Kaon and B-meson mixing and decay, Neutron EDM.,Current constraints (II): collider searches,signal relevant to RH scalar triplet,signal relevant to RH neutrino,Summary of constraints,Kaon mxing constraints,When , there exists a large range for he
7、avy neutrino mass.,Meson LNV decays,Resonance enhancement effect,In Type I seesaw,In LR seesaw model,(1) heavy neutrino mass have a large range;,(2) have rich stucture in CC interaction.,Meson LNV decays will have a different feature in LR seesaw model.,Constraint heavy neutino masses and heavy-ligh
8、t mixing,Motivation,(1) Meson LNV decays mediated by on shell heavy neutrino in LR seesaw model;,(2) Based on some assumption, predict the decay rates of meson LNV decays;,(3) Using the experimental data to constraint heavy neutrino mass and heavy-light mixing.,2. LR seesaw model,Gauge group and fie
9、lds,Gauge group,fermion fields,scalar fields,VEV,with and .,Fields and VEV,Lepton mass term,after spontaneous symmetry breaking,where,with,Yukawa interactions,Diagonalization ( I ),Charged lepton,Seesaw formula,Neutrino,where,Diagonalization ( II ),with,Gauge couplings (I),The kinetic terms for ferm
10、ions,where,Gauge couplings (II),Mixings of W_L and W_R,Mass matrix,Mixning,with , and the masses for physical gauge bosons,Mixings of Z and Z,Mass matrix,Mixning,with , ,and the masses for physical gauge bosons,(in basis ),Summary of interactions,(1) Down quark and charged leptons in mass basis;,(2)
11、 Ignoring the mixings of gauge bosons;,Simplification and assumptions,(3) Only one heavy neutrino;,Meson LNV decays mediated by on-shell heavy neutrino are mainly from,Due to the heavy masses of new gauge bosons, the decay rate of heavy neutrino with mass below SM gauge bosons is the same as Type I
12、seesaw.,3. Analytical evaluation,Feynman diagrams,Amplitude (I),Leptonic amplitude,Amplitude (II),Total amplitude,where,Meson are all pseudoscalar meson,Technique,SDE,NWA,The decay rate of heavy neutrino,4. Numerical results,Basic inputs,Discussion,(1) When heavy-light mixing S2 is 10-3, LL part has
13、 main contribution to meson LNV decays;,(2) If heavy-light mixing S2 becomes much smaller, RH part(RR, LR, RL) has main contribution to meson LNV decays;,(3) The mass of WR, heavy-light mixing S, and heavy neutrino mass all influence the decay rate of meson LNV decays;,(4) Based on the current exper
14、imental data, constraining heavy neutrino mass and mixing are working in progress due to the low efficiency of program brought by a relatively complicated dependence of decay rate on heavy-light mixing S.,5. Conclusion,1.LR seesaw model have appealing features;,2.Meson LNV decays mediated by on-shel
15、l heavy neutrino has been investigated;,Conclusion,Thanks for your attention,a. Prediction and comparison based on some inputs;,b. Using experimental bounds to constraint heavy neutrino mass and heavy-light mixing.,3.Meson LNV decays provide a possible way to search Majorana neutrino in LR seesaw model.,
