Experiments are planned to improve the sensitivity of mu-e conversion from the current ~ 10^{-12} to 10^{-16} - 10^{-18}. If the muon (bound to the nucleus) could be polarised, a spin asymmetry of the final state electron is sensitive to CP violating phases on lepton flavour violating operators. This is similar to extracting phases from asymmetries in the final state spin and phase space distributions of mu to 3e and mu to e gamma.
The flavor violating $μ^--e^-$ conversion in nuclei is studied within the minimal supersymmetric standard model. We focus on the R-parity violating contributions at tree level including the trilinear and the bilinear terms in the superpotential as well as in the soft supersymmetry breaking sector. The nucleon and nuclear structure have consistently been taken into account in the expression of the $μ^--e^-$ conversion branching ratio constructed in this framework. We have found that the contribution of the strange quark sea of the nucleon is comparable with that of the valence quarks. From the …
The coherent muon-electron conversion rates in various nuclei are calculated for general lepton flavor violating interactions. We solve the Dirac equations numerically for the initial state muon and the final state electron in the Coulomb force, and perform the overlap integrals between the wave functions and the nucleon densities. The results indicate that the conversion branching ratio increases for a light nucleus up to the atomic number Z ~ 30, is largest for Z = 30 -- 60, and becomes smaller for a heavy nucleus with Z > (~ 60). We also discuss the uncertainty from the input proton and neu…
There is no guarantee that the violation of lepton number, assuming it exists, will primarily manifest itself in neutrinoless double beta decay ($0νββ$). Lepton-number violation and lepton-flavor violation may be related, and much-needed information regarding the physics that violates lepton number can be learned by exploring observables that violate lepton flavors other than electron flavor. One of the most promising observables is $μ^- \rightarrow e^+$ conversion, which can be explored by experiments that are specifically designed to search for $μ^- \rightarrow e^-$ conversion. We survey lep…
We present a new class of constraints to the lepton-family number and R-parity violating couplings from muonium conversion, $μ^{-} + {_{22}^{48}} Ti \to e^{-} + {_{22}^{48}} Ti$, a class of tau decays, $τ\to l +$ (light meson) with $l= μor e$, and $J/ψ$ and $π^0$ decays into a lepton pair. We find that $μ^{-} + {_{22}^{48}} Ti \to e^- + {_{22}^{48}} Ti$ provides one of the strongest constraints along with $Δm_{K}, Δm_{B}$, $μ\to e γ$ and the neutrinoless double $β$ decay. Search for these lepton-family number violating (LFNV) decays forbidden in the standard model is clearly warranted in vario…
In general, attempts to extend the standard model will include extra gauge structure. We parameterize string and technicolor models for a Z' boson with primitive lepton flavor violating interactions. Calculations for its muon conversion rate (mu N -> e N) on Titanium are made and used to show the potential of forthcoming experiments MECO at Brookhaven National Laboratory and PRIME at the Japan Hadron Facility (to be renamed). For reasonable choices of parameters, such U(1) bosons with masses the order 10 TeV and mu-e Z' charge as low as ~10^-5 are demonstrated to be accessible for MECO and PRI…
We have studied lepton flavor violation processes $μ\to eγ$ and $μ-e$ conversion in nuclei induced by unparticle. Both ${\rm Br}(μ\to eγ)$ and $μ-e$ conversion rate ${\rm CR}(μ-e,{\rm Nuclei})$ strongly depend on the scale dimension $d_{\cal U}$ and the unparticle coupling $λ^{ff'}_{\rm K}$(K=V, A, S, P). Present experimental upper bounds on ${\rm Br}(μ\to eγ)$, ${\rm CR}(μ-e,{\rm Ti})$ and ${\rm CR}(μ-e,{\rm Au})$ put stringent constraints on the parameters of unaprticle physics. The scale dimensions $d_{\cal U}$ around 2 are favored for the unparticle scale $Λ_{\cal U}$ of ${\cal O}(10 {\rm …
We compare two most relevant loop induced muon number violating processes, μ--> e γand μ-e conversion in nuclei, in constraining new physics. Because of much richer structure of the latter process it may be enhanced with respect to μ--> e γby a large $\ln(m^2_μ/Λ^2),$ where $Λ$ is the scale of the new physics. After model-independent considerations we present two examples constraining the R-parity violating couplings of MSSM and the off-diagonal couplings of the doubly charged Higgs bosons from the non-observation of μ-e conversion.
We analyze the lepton flavor violating process $μ-e$ conversion in the framework of the minimal R-symmetric supersymmetric standard model. The theoretical predictions are determined by considering the experimental constraint on parameter $δ^{12}$ from the lepton flavor violating decay $μ\rightarrow e γ$. The numerical results show that $γ$ penguins and Z penguins dominate the predictions on CR($μ-e$,Nucleus), and the contributions from Higgs penguins and box diagrams are insignificant. The theoretical predictions on conversion rate CR($μ-e$,Nucleus) in a Al or Ti target can be enhanced close t…
A detailed study of the muonic analogue of neutrinoless double beta decay, (muon^-,muon^+) conversion, has been carried out for the A=44 nuclear system. We studied several lepton number violating (LNV) mechanisms potentially triggering this process: exchange by light and heavy Majorana neutrinos as well as exchange by supersymmetric particles participating in R-parity violating interactions. The nuclear structure has been taken into account within the renormalized Quasiparticle Random Phase Approximation method. To our knowledge, this is the first realistic treatment of nuclear structure aspec…
A lepton-flavor violating (LFV) Z' boson may mimic some of the phenomena usually attributed to supersymmetric theories. Using a conservative model of LFV Z' bosons, the recent BNL E821 muon g-2 deviation allows for a LFV Z' interpretation with a boson mass up to 4.8 TeV while staying within limits set by muon conversion, mu -> e gamma, and mu -> eee. This model is immediately testable as one to twenty e^+e^- -> mu tau events are predicted for an analysis of the LEP II data. Future muon conversion experiments, MECO and PRIME, are demonstrated to have potential to probe very high boson masses wi…
The determination of CP violating phases in the Majorana neutrino mixing matrix using phenomenological constraints from neutrino oscillations, neutrinoless double beta decay, ($μ^-, e^+$) conversion and few other processes is discussed. We give the expressions for the phases in terms of the mixing angles and masses consistent with the recent data from Kamiokande.
Lepton-flavor-violating decays of light pseudoscalars, $P=π^0,η,η'\toμe$, are stringently suppressed in the Standard Model up to tiny contributions from neutrino oscillations, so that their observation would be a clear indication for physics beyond the Standard Model. However, in effective field theory such decays proceed via axial-vector, pseudoscalar, or gluonic operators, which are, at the same time, probed in spin-dependent $μ\to e$ conversion in nuclei. We derive master formulae that connect both processes in a model-independent way in terms of Wilson coefficients, and study the implicati…
We consider the case that $μ$-$e$ conversion signal is discovered but other charged lepton flavor violating (cLFV) processes will never be found. In such a case, we need other approaches to confirm the $μ$-$e$ conversion and its underlying physics without conventional cLFV searches. We study R-parity violating (RPV) SUSY models as a benchmark. We briefly review that our interesting case is realized in RPV SUSY models with reasonable settings according to current theoretical/experimental status. We focus on the exotic collider signatures at the LHC ($pp \to μ^- e^+$ and $pp \to jj$) as the othe…
We discuss the constraints of lepton mixing angles from lepton number violating processes such as neutrinoless double beta decay, (μ^-)-(e^+) conversion and K decay, $K^- \to π^+μ^-μ^-$ which are allowed only if neutrinos are Majorana particles. The rates of these processes are proportional to the averaged neutrino mass defined by $<m_ν >_{a b}\equiv |\sum_{j=1}^{3}U_{a j} U_{b j}m_j|$ in the absence of right-handed weak coupling. Here $a, b (j)$ are flavour(mass) eigen states and $U_{a j}$ is the left-handed lepton mixing matrix. We obtain the consistency conditions which are satisfied irrele…
We re-examine resonant massless-neutrino conversions in a dense medium induced by flavour changing neutral current (FCNC) interactions. We show how the observed $\barν_e$ energy spectra from SN1987a and the supernova $r$-process nucleosynthesis provide constraints on supersymmetric models with $R$ parity violation, which are much more stringent than those obtained from the laboratory. We also suggest that resonant massless-neutrino conversions may play a positive role in supernova shock reheating. Finally, we examine the constraints on explicit $R$-parity-violating FCNCs in the presence of non…
We consider the case that $μ$-$e$ conversion signal is discovered but other charged lepton flavor violating (cLFV) processes will never be found. In such a case, we need other approaches to confirm the $μ$-$e$ conversion and its underlying physics without conventional cLFV searches. We study R-parity violating (RPV) SUSY models as a benchmark. We briefly review that our interesting case is realized in RPV SUSY models with reasonable settings according to current theoretical/experimental status. We focus on the exotic collider signatures at the LHC ($pp \to μ^- e^+$ and $pp \to jj$) as the othe…
Considering the constraints from the experimental data on $μ\rightarrow eγ$, $μ\rightarrow3e$, $μ-e$ conversion etc., we analyze the Lepton Flavor Violating decays $ϕ(J/Ψ,Υ(1S)) \rightarrow e^+μ^-(μ^+τ^-)$ in the scenarios of the minimal supersymmetric extensions of Standard Model with seesaw Mechanism. Numerically, there is parameter space that the LFV processes of $J/Ψ(Υ)\rightarrowμ^+τ^-$ can reach the upper experimental bounds, meanwhile the theoretical predictions on $μ\rightarrow eγ$, $μ\rightarrow3e$, $μ-e$ conversion satisfy the present experimental bounds. For searching of new physics…
We consider the case that $μ$-$e$ conversion signal is discovered but other charged lepton flavor violating (cLFV) processes will never be found. In such a case, we need other approaches to confirm the $μ$-$e$ conversion and its underlying physics without conventional cLFV searches. We study R-parity violating (RPV) SUSY models as a benchmark. We briefly review that our interesting case is realized in RPV SUSY models with reasonable settings according to current theoretical/experimental status. We focus on the exotic collider signatures at the LHC ($pp \to μ^- e^+$ and $pp \to jj$) as the othe…
We investigate charged lepton flavor violating processes $μ\rightarrow e γ$, $μ\rightarrow e e \overline{e}$ and $μ-e$ conversion in nuclei for a class of three-loop radiative neutrino mass generation models with electroweak multiplets of increasing order. We find that, because of certain cancellations among various one-loop diagrams which give the dipole and non-dipole contributions in effective $μe γ$ vertex and Z-penguin contribution in effective $μe Z$ vertex, the flavor violating processes $μ\rightarrow eγ$ and $μ-e$ conversion in nuclei become highly suppressed compared to $μ\rightarrow …
It is shown that the polarizations of the final particles in $μ^+\to e^+e^-e^+$ provide us with information on the CP-violating phases of the effective Lagrangian leading to this Lepton Flavor Violating (LFV) decay.
Possible CP violation in supersymmetric (SUSY) extensions of the Standard Model (SM) is discussed. The consequences of CP violating phases in the gaugino masses, trilinear soft supersymmetry-breaking terms and the `mu' parameter are explored. Utilizing the constraints on these parameters from electron and neutron electric dipole moments, possible CP violating effects in B-physics are shown. A set of measurements from the B-system which would overconstrain the above CP violating phases is illustrated.
We study a CP and T violating triple (spin) correlation in the muon to electron conversion in nuclei in the context of the seesaw mechanism. After concluding that the results are negative for all three seesaw types, we turn to the left-right symmetric theories as the original source of seesaw. We find that in general this correlation is of order one which offers a hope of observing CP violation in lepton flavor violating processes for a L-R scale below around 10-30 TeV. We discuss the conditions that could render to (unlikely) conspiracies as to suppress the CP violating effects.
Assuming a new interaction with a $θ$ term for the third generation of quarks, a value of $θ$ different from zero dynamically induces the top- bottom mass splitting and a large CP-violating phase.
A dynamical scheme where the third generation of quarks plays a distinctive role is implemented. New interactions with a $θ$ term induce the breaking of the electroweak symmetry and the top-bottom mass splitting. A large CP-violating phase naturally follows from the latter.
We propose an idea that the observed CP violation in neutrino oscillation is originated from the phase in right-handed neutrino mixing by seesaw mechanism. We add small breaking terms $M_{ij}N_{R_i}N_{R_j} $ in model based on $A_4$ symmetry to generate non-diagonal right-handed neutrino mixing, which will give a small correction to TBM mixing via seesaw mechanism with nonzero reactor angle and CP violating phase. We estimate the CP violating phase by investigating the process of leptogenesis due to the decay of right-handed neutrino.
We have analyzed the electric dipole moment and the Higgs mass constraints on the supersymmetric model which offers dynamical solutions to the μand strong CP problems. The trilinear coupling phases, and \tanβ-|μ| are strongly correlated, particularly in the low-\tanβregime. Certain values of the phases of the trilinear couplings are forbidden, whereas the CP violating phase from the chargino sector is imprisoned to lie near a CP conserving point, by the Higgs mass and electric dipole moment constraints.
The standard CKM model can be tested and New Physics detected using only CP-violating phase measurements in B decays. This requires the measurement of a phase factor which is small in the Standard Model, in addition to the usual large phases $β$ and $γ$. We also point out that identifying violations of the unitarity of the CKM matrix is rather difficult, and cannot be done with phase measurements alone.
We compute the net electric current generated during a first order electroweak phase transition when fermions transit from the false to the true vacuum. This current is generated by the CP-violating fermion interaction with the Higgs during the phase transition and is quantified in terms of a CP-violating phase in the bubble wall separating the symmetric from the symmetry-broken phases. We comment on the seed magnetic field that this current is able to generate and it is possible implications for magnetogenesis in the early universe during the electroweak phase transition.
We present a solution to the strong CP problem based on the identification of the theta angle with twice the CP violating phase present in the CKM quark matrix. This solution washes out all the unwanted issues stemming form the strong CP phase and is strongly justified by general theoretical arguments based on the partition function associated to the $θ$ vacuum. Phenomenological consequences on the quark mass matrices are discussed for this case.
Effects of CP violation on the supersymmetric electro-weak correction to the anomalous magnetic moment of the muon are investigated with the most general allowed set of CP violating phases in MSSM. The analysis includes contributions from the chargino and the neutralino exchanges to the muon anomaly. The supersymmetric contributions depend only on specific combinations of CP phases. The independent set of such phases is classified. We analyse the effects of the phases under the EDM constraints and show that large CP violating phases can drastically affect the magnitude of the supersymmetric el…
For varying values of $\tanβ$, we study the effect of CP violating phases from the soft supersymmetry breaking terms in string-inspired models on the relic abundance and detection rates of the lightest neutralino (LSP). We find that the phases have no significant effect on the LSP relic abundance but can have a substantial impact on the detection rates.
We explore the theoretical constraints on the observable parameters of neutrino mixing on predictions for the leptonic Dirac CP-violating phase within a well-studied class of simple theoretical models that includes a single source of CP violation due to charged lepton corrections. The approach guarantees that a physically meaningful prediction for the most likely values for the leptonic Dirac CP-violating phase is obtained.
We reanalyze the constraints in neutrino masses and MNS lepton mixing parameters using the new data from the terrestrial (KamLAND) and astrophysical (WMAP) observations together with the HEIDELBERG-MOSCOW double beta decay experiment. It leads us to the almost degenerate or inverse hierarchy neutrino mass scenario. We discuss the possibility of getting the bound for the Majorana CP violating phase.
We combine experimental bounds on the electric dipole moments of the neutron and electron with cosmological limits on the relic density of a gaugino-type LSP neutralino to constrain certain CP-violating phases appearing in the MSSM. We find that in the Constrained MSSM, the phase |θ_μ| < π/10, while the phase θ_A remains essentially unconstrained.
It has recently been shown that by measuring the transverse polarization of the final particles in the LFV processes $μ\to eγ$, $μ\to eee$ and $μN\to e N$, one can derive information on the CP-violating phases of the underlying theory. We derive formulas for the transverse polarization of the final particles in terms of the couplings of the effective potential leading to these processes. We then study the dependence of the polarizations of $e$ and $γ$ in the $μ\to e γ$ and $μN \to e N$ on the parameters of the Minimal Supersymmetric Standard Model (MSSM). We show that combining the information…
We show that large SUSY phases have no significant effect on the relic density of the lightest supersymmetric particle (LSP). However, they are very significant for the detection rates. We emphasise that the phase of the trilinear coupling increase the direct and indirect detection rates.
We revisit the results of recent electroweak baryogenesis calculations and include all allowed large CP-violating supersymmetric phases. If the phases are large, the resulting baryon asymmetry can be considerably larger than the observed value $n_B/s \sim 4 \times 10^{-11}$. Much of the asymmetry must therefore be washed out, and we argue that the upper bound on the light Higgs mass is larger than the value reported in previous work.
We provide a detailed analysis of the supersymmetric tri-lepton signals for sparticle searches at the Tevatron in the minimal supersymmetric standard model with general CP-violating phases but without flavor mixing among sfermions of different generation. The stringent experimental constraints on the CP-violating phases from the electron and neutron electric dipole moments are included in the analysis for two exemplary scenarios of the SUSY parameters; one with decoupled first two generation sfermions and the other with non-decoupled sfermions. In both scenarios, the production cross section a…
We study the possibility of identifying the CP violating phases in the PMNS mixing matrix in the lepton sector and also that in the CKM mixing matrix in the quark sector with the phase responsible for the spontaneous CP violation in the Higgs potential, and some implications. Since the phase in the CKM mixing matrix is determined by experimental data, the phase in the lepton sector is therefore also fixed. The mass matrix for neutrinos is constrained leading to constraints on the Jarlskog CP violating parameter $J$, and the effective mass $<m_{ββ}>$ for neutrinoless double beta decay. The Yuka…
We analyze neutrino oscillation for the general case when the initial neutrino is not in a pure flavor state. We show that, after such a neutrino beam propagates for a while, the probability of detecting any pure flavor state depends even on the CP-violating Majorana phases in the mixing matrix. The dependence remains even when energy spectrum of the initial beam is taken into account. We discuss various implications of this dependence.
We point out an elegant mechanism to predict a maximal atmospheric angle, which is based on a maximal CP violating phase difference between second and third lepton families in the flavour symmetry basis. In this framework, a discussion of the predictions for theta_{12}, |U_{e3}|, delta and their possible correlations is provided. We also present an explicit realisation in terms of an SO(3) flavour symmetry model.
We study the neutralino relic density and the neutralino-proton elastic scattering cross sections in the minimal supersymmetric standard model (MSSM) with CP-violating phases. We include all the final states to the neutralino pair annihilation cross section at the tree level, taking into account the mixing between the CP-even and CP-odd neutral Higgs fields. We show that variations of the relic density and the elastic scattering cross sections with the CP-violating phases are significant. In particular, interferences between the major contributions in the neutralino annihilation cross section …
An analysis of the electric dipole moment (EDM) of the neutron and of the leptons in the minimal supersymmetric standard model (MSSM) with the most general allowed set of CP violating phases without generational mixing is given. The analysis includes the contributions from the gluino, the chargino and the neutralino exchanges to the electric dipole operator, the chromoelectic dipole operator, and the CP violating purely gluonic dimension six operator. It is found that the EDMs depend only on certain combination of the CP phases. The independent set of such phases is classified. The analysis of…
We use a new weak basis invariant approach to classify all the observable phases in any extension of the Standard Model (SM). We apply this formalism to determine the invariant CP phases in a simplified version of the Minimal Supersymmetric SM with only three non-trivial flavour structures. We propose four experimental measures to fix completely all the observable phases in the model. After these phases have been determined from experiment, we are able to make predictions on any other CP-violating observable in the theory, much in the same way as in the Standard Model all CP-violation observab…
We present a new observable sensitive to a certain combination of CP violating phases in supersymmetric extensions of the Standard Model, viz. a triple product of momenta in the cascade decay of a heavy squark via an on-shell neutralino and off-shell slepton. We investigate the regions of parameter space in which the signal is strong enough to be detectable at the LHC with $\sim \bigl(10^2-10^3\bigr)/\sin^2(2Δϕ)$ identified events, where $Δϕ$ is a certain combination of phases in the MSSM presented in the text.
We revisit the neutrino magnetic moments (MMs) in the left-right model with non-manifest symmetry. After deriving an expression in terms of the Dirac and Majorana phases, we analyze the sensitivity of neutrino MMs to these $CP$-violating phases in two scenarios: 1) a maximal right mixing in which left- and right-handed neutrinos are mixed by the same matrix; and 2) a right-handed neutrino mixing whose off-diagonal entries are much smaller than the elements in the diagonal, but where the $CP$ phases remain general. Our results show that, even though certain values of the Majorana phases can eli…
At a future Linear Collider one will be able to determine the masses of charginos and neutralinos and their pair production cross sections to high accuracies. We show how systematically including the cross sections into the analysis improves the measurement of the underlying mass parameters, including potential CP violating phases. In addition, we investigate how experimental errors will affect the determination of these parameters. We present a first estimate on the lower limit of observable small phases and on the accuracy in determining large phases.
The infrared attractiveness of soft-supersymmetry breaking (SSB) parameters is investigated in extra dimensions. The SSB parameters are assumed to run from the Planck scale M_{PL} down to the GUT scale M_{GUT}. We find that, even for M_{PL}/M_{GUT}=100, the SSB parameters in six dimensions can align out of their anarchical disorder at M_{PL} in such a way that flavor-changing neutral currents as well as dangerous CP-violating phases are sufficiently suppressed at M_{GUT}. A concrete, realistic example based on SU(5) in six dimensions is presented.
Taking the established nonzero value of $θ_{13}$, we study the possibility of extracting the Dirac CP-violating phase by a beta beam facility with a boost factor $100<γ<450$. We compare the performance of different setups with different baselines, boost factors and detector technologies. We find that an antineutrino beam from $^6$He decay with a baseline of $L=1300$ km has a very promising CP discovery potential using a 500 kton Water Cherenkov (WC) detector. Fortunately this baseline corresponds to the distance between FermiLAB to Sanford underground research facility in South Dakota.
We analyze the neutralino-nucleus elastic cross-section in the MSSM, including contributions from CP-violating phases, using the four-fermi neutralino-quark interaction. Over a wide range of the MSSM parameter space we show the variations in the cross-sections due to these phases. We further concentrate on the regions which are consistent with constraints from the electric dipole moment of the electron, neutron and mercury atom. In the regions we examine in detail, we find suppressions by up to a factor of two, while enhancements in the cross-sections are no greater than $\sim$ 10%.
We discuss the testability of CP-violating phases at future lepton colliders for the scenario which satisfies electric dipole moment data by destructive interferences among several phases. We consider the general but aligned two Higgs doublet model which has the CP-violating phases in the Higgs potential and the Yukawa interaction. The Yukawa interaction terms are aligned to avoid flavor changing neutral currents at tree level. The Higgs potential is also aligned such that the coupling constants of the lightest Higgs boson with the mass of 125 GeV to the Standard Model (SM) particles are the s…
