The recent measurement of the like-sign dimuon charge asymmetry in semileptonic b-hadron decays by the D0 Collaboration is about 3 sigmas away from the standard-model prediction, hinting at the presence of CP-violating new physics in the mixing of B_s mesons. We consider the possibility that this anomalous result arises from the contribution of a light spin-1 particle. Taking into account various experimental constraints, we find that the effect of such a particle with mass below the b-quark mass can yield a prediction consistent with the anomalous D0 measurement within its one-sigma range.
The ratio of the B+ B- and B0 B0bar production rates in e+ e- annihilation is computed as a function of the B meson velocity and BB* pi coupling constant, using a non-relativistic effective field theory.
The energy spectra of the b and bbar quarks in e+e- -> t tbar with t -> b W (tbar -> bbar W) are calculated assuming CP violation in the production process. Expressions for the corresponding CP violating asymmetries and optimal observables that determine the imaginary parts of the electric and weak dipole moment form factors of the top are derived. It is shown that polarization of the initial lepton beams is essential to disentangle Im d^γ(s) and Im d^{Z}(s). Numerical results are given in the Minimal Supersymmetric Standard Model with complex phases.
We show that the large, direct CP-violation parameter $A_{ππ}=-C_{ππ}$, reported by the BELLE collaboration in the decays Bbar^0(B^0) -> π^+π^-, implies an unusual situation in which the presence of a very large difference between two strong-interaction phases ~ -110 deg. plays an essential role. We make the demonstration within a model of strong, two-body quasi-elastic interactions between physical hadrons. The model can accommodate a large difference between two strong-interaction phases, for which it provides a natural enhancement.
Motivated by $-2 σ$ deviation from the Standard Model prediction for the forward--backward asymmetry of $Z \to b \bar{b}$ decay in the LEP data, we explore the anomalous couplings of $Z b \bar{b}$ vertex through the electroweak precision test extended by including $A_{FB}^b$. We introduce a new variable $ε'_b$ to measure the anomalous right-handed coupling in $Z b \bar{b}$ vertex. Implications of our analysis on the nonuniversal contact interactions are studied and the left-right model is also considered as a possible origin of the anomalous right-handed couplings.
Recent measurements of B^0 -> pi pi decays reveal two features that are in conflict with conventional calculations: the channel B^0 (Bbar^0) -> pi^+ pi^- shows a large direct CP-violating asymmetry, and the channel B^0 (B^0) -> pi^0 pi^0 has an unexpectedly high branching ratio. We show that both features can be understood in terms of strong-interaction mixing of pi pi and D Dbar channels in the isospin-zero state, an effect that is important because of the large experimentally observed ratio Gamma(B^0 / Bbar^0 -> D^+ D^-) / Gamma (B^0 / Bbar^0 -> pi^+ pi^-) approx. 50. Our dynamical model cor…
The process gamma gamma \to mu tau b bbar is studied in the minimal supersymmetric standard model within a large tan_beta scenario imposing on the parameter space present direct and indirect constraints from B physics and rare LFV tau-decays. At a photon collider based on an e+e- linear collider with a center of mass energy of 800 GeV with the parameters of the TESLA proposal (expected integrated gamma-gamma luminosity L=200-500 inverse fb) the LFV signal can be probed for masses of the heavy neutral Higgs bosons A,H from 300 GeV up to the kinematical limit ~ 600 GeV for tan_beta in the range …
In the Left-Right Symmetric Model (LRSM), box diagrams involving the charged right-handed gauge boson W_R may affect B-Bbar mixing as well as CP asymmetries in neutral B decays. The smallness of the epsilon_K parameter in the neutral K-meson system places severe constraints on the right-handed quark mixing matrix V^R, and reduces the number of its effective phases to one. W_R exchange gives a large contribution to B-Bbar mixing when the mass of the W_R boson is up to or higher than 8 TeV, depending on the V^R case, the B_d,s meson, and the asymmetry. The allowed regions of the CP violating asy…
It is expected that, within the next three years, the determination of the CKM matrix elements with the least theoretical uncertainty will arise from the measurements of CP violation in B_d --> J/ψK_S decays and from Bs-Bsbar mixing. If there is significant new physics in Bs-Bsbar mixing, then those experiments will not yield the correct values for the CKM matrix elements. As a result, a qualitative signal of new physics may appear in the CP violation of decays like B_d --> pi+ pi-.
We calculate the decay width of h0 -> b bbar in the Minimal Supersymmetric Standard Model (MSSM) with quark flavour violation (QFV) at full one-loop level. We study the effect of scharm-stop mixing and sstrange-sbottom mixing taking into account the constraints from the B meson data. We discuss and compare in detail the decays h0 -> c cbar and h0 -> b bbar within the framework of the perturbative mass insertion technique using the Flavour Expansion Theorem. The deviation of both decay widths from the Standard Model values can be quite large. Whereas in h0 -> c cbar it is almost entirely due to…
We present a systematic analysis of the angular distribution of Bbar -> Kbar^\ast (-> Kbar pi) l^+ l^- decays with l = e, mu in the low recoil region (i.e. at high dilepton invariant masses of the order of the mass of the b-quark) to account model-independently for CP violation beyond the Standard Model, working to next-to-leading order QCD. From the employed heavy quark effective theory framework we identify the key CP observables with reduced hadronic uncertainties. Since some of the CP asymmetries are CP-odd they can be measured without B-flavour tagging. This is particularly beneficial for…
We investigate single top production in the presence of anomalous Wtb couplings. We explicitly show that, if these couplings arise from gauge invariant effective operators, the only relevant couplings for single top production and decay are the usual gamma^mu and sigma^mu nu q_nu terms, where q is the W boson momentum. This happens even in the single top production processes where the Wtb interaction involves off-shell top and/or bottom quarks. With this parameterisation for the Wtb vertex, we obtain expressions for the dependence on anomalous couplings of the single top cross sections, for (i…
The light axigluon model of Tavares and Schmaltz is a viable candidate to explain the Tevatron t-tbar forward-backward asymmetry. In this paper we present the forward-backward asymmetries for b-bbar and c-cbar systems predicted by the light axigluon. Furthermore, we modify this model to include flavor changing couplings of axigluons with the SM quarks. We constrain these couplings from the available neutral meson mixing data, and investigate their effects on the rare decay B^0_s -> mu^+ mu^-, CP violating D -> h^+ h^- and isospin violating B -> K^(*) mu^+ mu^- decays. We show that a light axig…
We review CP-violating effects in Z --> 3 jet and Z --> 4 jet decays, assuming the presence of CP-violating effective Z b bbar G and Z b bbar G G couplings. Longitudinal beam polarization is included in the studies. We propose a direct search for such CP-violating couplings by using various CP-odd observables. The data of a future linear collider running at the Z-resonance in the so-called GigaZ option should give significant information on the couplings. Finally we show that stringent bounds on the mass of excited b quarks can be derived if appropriate couplings are of a size characteristic o…
We study the Higgs boson decays $h^0 \to c \bar{c}, b \bar{b}, b \bar{s}, γγ, g g$ in the Minimal Supersymmetric Standard Model (MSSM) with general quark flavor violation (QFV), identifying the $h^0$ as the Higgs boson with a mass of 125 GeV. We compute the widths of the $h^0$ decays to $c \bar c, b \bar b, b \bar s (s \bar b)$ at full one-loop level. For the $h^0$ decays to photon photon and gluon gluon we compute the widths at NLO QCD level. We perform a systematic MSSM parameter scan respecting all the relevant constraints, i.e. theoretical constraints from vacuum stability conditions and e…
We present the NLO corrections to the Wilson coefficients of the Delta F = 2 Hamiltonians in the strong interacting sector of the MSSM, responsible for neutral meson oscillations. Such corrections, combined with the NLO anomalous dimension matrix for the Delta F = 2 operators and the corresponding hadronic matrix elements calculated on the lattice, allow for the first time a full NLO phenomenological analysis of the observables related to meson oscillations. We present preliminary results in the B_d - B_d bar sector.
The status of CP violation and the CKM matrix is reviewed. Direct CP violation in B decay has been established and the measurement of sin(2beta) in ψK modes reached 5% accuracy. I discuss the implications of these, and of the possible deviations of the CP asymmetries in b->s modes from that in ψK. The first meaningful measurements of alpha and gamma are explained, together with their significance for constraining both the SM and new physics in B-Bbar mixing. I also discuss implications of recent developments in the theory of nonleptonic decays for B->pi K rates and CP asymmetries, and for the …
We review some recent results on b decays relevant to future CP violation studies. In particular, some new data on rare hadronic B decays will be presented, as well as inclusive searches for evidence for gluonic penguins and first hints of final state interaction phases in B decays to D* rho. The results discussed are based on data collected by the CLEO experiment including up to 5.8 x 10 ^6 B Bbar pairs.
We obtain constraints on the mixing of vector-like quarks coupling predominantly to the third generation. We consider all (seven) relevant types of vector-like quarks, individually. The constraints are derived from oblique corrections and Z -> b bbar measurements at LEP and SLC. We investigate the implications of these constraints on LHC phenomenology, concerning the decays of the heavy quarks and their single production. We also explore indirect effects of heavy quark mixing in top and bottom couplings. A remarkable effect is the possibility of explaining the anomalous forward-backward asymme…
We consider the impact of R-parity violating suprsymmetry in the nonleptonic decay B --> pi+ pi-. This is one of the rare instances where new physics contributes to both B-Bbar mixing and B --> pi+ pi- decay. We do a numerical analysis to capture the interplay between these two effects and place constraints on the relevant parameter space.
We analyse three different New Physics scenarios for Delta F=2 flavour-changing neutral currents in the quark sector in the light of recent data on neutral-meson mixing. We parametrise generic New Physics contributions to B_q-Bbar_q mixing (q=d,s), in terms of one complex quantity Delta_q, while three parameters Delta_K^tt, Delta_K^ct and Delta_K^cc are needed to describe K-Kbar mixing. In Scenario I, we consider uncorrelated New Physics contributions in the B_d, B_s, and K sectors. In this scenario, it is only possible to constrain the parameters Delta_d and Delta_s whereas there are no non-t…
In light of the increasing hints of new physics at the muon $g-2$ and neutrino oscillation experiments, we consider the recently observed tension in the long-baseline neutrino oscillation experiments as a potential indication of Lorentz invariance violation. For this purpose, the latest data from T2K and NO$ν$A is analysed in presence of non-minimal Lorentz invariance violation. Indeed, we find that isotropic violation in dimensions $D =$ 4, 5 and 6 can alleviate the tension in neutrino oscillation data by 0.4$-$2.4$σ$ CL significance, with the isotropic coefficient $γ^{(5)}_{ττ} =$ 3.58$\time…
The first part of this talk reviews recent developments in flavor physics that can be made without detailed understanding of hadronic physics, driven by the data. The error of sin(2beta) has shrunk below 5%, and the measurements of alpha and gamma have reached interesting precisions. For the first time, there are significant constraints on the deviations from the standard model in B-Bbar mixing and in b->s and b->d transitions. In the second part, I review some theoretical developments for exclusive semileptonic and nonleptonic B decays that have become possible using the soft-collinear effect…
We study the determination of gamma from CP-violating observables in B -> pi+ pi- and B -> psi K_S. This determination requires theoretical input to one combination of hadronic parameters. We show that a mild assumption about this quantity may allow bounds to be placed on gamma, but we stress the pernicious effects that an eightfold discrete ambiguity has on such an analysis. The bounds are discussed as a function of the direct (C) and interference (S) CP-violating observables obtained from time-dependent B -> pi+ pi- decays, and their behavior in the presence of new physics effects in B-Bbar …
We study genuine CP-odd observables at the LHC to test the CP property of the ZZH interaction for a Higgs boson with mass below the threshold to a pair of gauge bosons via the process p,p -> Z,H -> l+,l-,b,bbar. We illustrate the analysis by including a CP-odd ZZH coupling, and show how to extract the CP asymmetries in the signal events. After selective kinematical cuts to suppress the SM backgrounds plus an optimal Log-likelihood analysis, we find that, with a CP violating coupling btilde = 0.25, a CP asymmetry may be established at a 3 sigma (5 sigma) level with an integrated luminosity of a…
We calculate the complete three-loop O(alpha_s^3) anomalous dimension matrix for the dimension-five dipole operators that arise in the Standard Model after integrating out the top quark and the heavy electroweak bosons. Our computation completes the three-loop anomalous dimension matrix of operators that govern low-energy |Delta F| = 1 flavor-changing processes, and represents an important ingredient of the next-to-next-to-leading order QCD analysis of the Bbar -> X_s gamma decay.
We use the BNL E821 measurement of g - 2, the anomalous magnetic moment of the muon, to normalize, within a supersymmetric GUT framework, constrained MSSM (CMSSM) predictions for processes that violate charged-lepton flavour conservation, including mu to e gamma, mu to e conversion and K^0_L to mu e. We illustrate our analysis with two examples of lepton mass matrix textures motivated by data on neutrino oscillations. We find that mu to e gamma may well occur at a rate within one or two (two or three) orders of magnitude of the present experimental upper limit if g - 2 is within the one- (two-…
We match the Higgs sector of the most general flavour breaking and CP violating minimal supersymmetric standard model (MSSM) onto a generic two-Higgs-doublet model, paying special attention to the definition of tan beta in the effective theory. In particular no tan beta-enhanced loop corrections appear in the relation to tan beta defined in the DRbar scheme in the MSSM. The corrections to the Higgs-mediated flavour-changing amplitudes which result from this matching are especially relevant for the B_d and B_s mass differences dM_s,d for minimal flavour violation, where the superficially leadin…
We explore the CP violation in $B \to ϕK$ decay processes in the presence of the anomalous right-handed $\bar{t}sW$ and $\bar{t}bW$ couplings. The complex anomalous top coupling can be a source of the new CP violation and lead to a deviation of the observed weak phase in $B \to ϕK$ decays, which takes account for the present disagreement of the observed $\sin 2 β$ between $B \to J/ψK$ and $B \to ϕK$ decays. The direct CP violation is also predicted.
Recent CP violation results in B decays suggest that Z penguins may have large weak phase. This can be realized by the four generation (standard) model. Concurrently, B to Xs l+ l- and Bs mixing allow for sizable Vt's* Vt'b only if it is nearly imaginary. Such large effects in b to s transitions would affect s to d transitions, as kaon constraints would demand Vt'd different from zero. Using Gamma(Z to b bbar) to bound |Vt'b|, we infer sizable |Vt's| < |Vt'b| < |Vus|$. Imposing epsilon_K, K+ to pi+ nu nubar and epsilon'/epsilon constraints, we find Vt'd* Vt's = few x 10^(-4) with large phase, …
We examine a class of Froggatt-Nielsen models with an anomalous U(1) as the flavor dependent symmetry. Anomaly cancellation and unbroken supersymmetry impose constraints on the U(1)_X charges of the fermions and the vacuum expectation values of the symmetry-breaking scalars. We show by example that it is possible to find models that reproduce the observed masses and mixings of the standard model fermions, and exhibit a realistic amount of CP violation.
Supersymmetric scenarios with R-parity conservation are becoming very constrained due to the lack of missing energy signals, thus motivating those scenarios with R-parity violation. In view of this, we consider a supersymmetric model with R-parity violation and extended by an anomalous horizontal $U(1)_H$ symmetry, where a self-consistent framework with baryon-number violation is achieved along with a proper supression for lepton number violating dimension-5 operators in order to keep a proton decay safe. With the introduction of right-handed neutrinos both Dirac and Majorana masses can be acc…
The effective supersymmetric theory (ESUSY) with R parity conservation cannot give a large anomalous magnetic moment of $μ$. It is pointed out that the flavor conservation and a large $(g-2)_μ$ within the experimental limits are achievable in the ESUSY with R parity violating couplings involving the third generation superparticles.
The contributions from the Ochanomizu CP Study Group to the KEK meetings on "CP violation and its origin" (1993-1997) are summarized on electroweak baryogenesis and anomalous W-boson couplings. We survey planned new experiments which could examine some aspects studied in our contributions. We also discuss several issues on baryogenesis. Ten problems are presented for further studies.
Recent evidence for anomalous CP violation in B-meson oscillations can be interpreted as resulting from CPT violation. This yields the first sensitivity to CPT violation in the B_s^0 system, with the relevant coefficient for CPT violation constrained at the level of parts in 10^{12}.
Recently there has been a renewed activity in the physics of violations of Lorentz invariance in the neutrino sector. Flavor dependent Lorentz violation, which generically changes the pattern of neutrino oscillations, is extremely tightly constrained by oscillation experiments. Flavor independent Lorentz violation, which does not introduce new oscillation phenomena, is much more weakly constrained with constraints coming from time of flight and anomalous threshold analyses. We use a simplified rotationally invariant model to investigate the effects of finite baselines and energy dependent disp…
There is a growing evidence for the anomalously large semileptonic CP asymmetry in the B meson system measured at the Tevatron. The noncontractible space, as an alternative symmetry-breaking mechanism to the Higgs mechanism, can change standard field theoretic calculations of the physical processes mediated through quantum loops for large external momenta or large internal masses. The presence of the W bosons and t-quarks in loops of the B meson mixing can enhance the corresponding semileptonic CP asymmetry when the loop integration is up to the universal Lorentz and gauge invariant UV cut-off…
We calculate the effect of new CP violating interactions parameterized by an anomalous $tbW$ coupling on CP-odd observables in B decays. We find that couplings consistent with current bounds induce observable effects in some CP asymmetries that will be measured in B-factories. The new effects are sufficiently large that they can actually test specific models that give rise to these $tbW$ interactions.
The most stringent bounds on the anomalous magnetic and electric dipole moments of the tau lepton was derived by Escribano and Massó[6] from the Z width at LEP in an effective lagrangian approach to the new physics. In this paper we point out that the higher dimensional operators introduced by Escribano and Massó not only modify the neutral currents of the tau lepton to Z gauge boson and the photon, but also induce lepton flavor violation (LFV). The size of the LFV effect depends crucially on the dynamics of the lepton mass generation. Assuming the lepton mass matrices in the form of an Fritzs…
We show that in a large class of models based on anomalous U(1) symmetry which addresses the fermion mass hierarchy problem, leptonic flavor changing processes are induced that are in the experimentally interesting range. The flavor violation occurs through the renormalization group evolution of the soft SUSY breaking parameters between the string scale and the U(1)_A breaking scale. We derive general expressions for the evolution of these parameters in the presence of higher dimensional operators. Several sources for the flavor violation are identified: flavor-dependent contributions to the s…
The patterns of R violation resulting from imposition of a gauged U(1) horizontal symmetry, on the minimal supersymmetric standard model are systematically analyzed. We concentrate on a class of models with integer U(1) charges chosen to reproduce the quark masses and mixings as well as charged lepton masses exactly or approximately. The U(1) charges are further restricted from the requirement that very large bilinear lepton number violating terms should not be allowed in the super-potential. It is shown that all the trilinear $λ'_{ijk}$ and all but at most two trilinear $λ_{ijk}$ couplings va…
Expecting the forthcoming experiment at the upgraded Fermilab Tevatron, we calculated CP-violating polarization asymmetry of t t-bar, A_{CP}= [sigma(p p-bar --> t(-) t-bar(-) X) - sigma(p p-bar --> t(+) t-bar(+) X)]/ sigma(p p-bar --> t t-bar X), due to possible anomalous chromomagnetic (kappa) and chromoelectric (tilde{kappa}) couplings of the gluon to the top quark. Since kappa and tilde{kappa} are sensitive to a contribution from new physics beyond standard model, this observable is useful to search for a signal of new physics. It was seen that the magnitude of A_{CP} depends only on Im(til…
A non-universal interaction, which involves only the third family leptons induces lepton flavor violating couplings and contributes to the anomalous magnetic moment of muon. In this paper, we study the effects of non-universal interaction on muon (g-2) and rare decay $τ\to μγ$ by using an effective lagrangian technique, and a phenomenological $Z^\prime$ model where $Z^\prime$ couples only to the third family lepton. We find that the deviation from the theory can be explained and the induced $τ\to μγ$ rate could be very close to the current experimental limit. In the $Z^\prime$ model, $M_{Z^\pr…
We compute the four-loop $n_f$ contribution proportional to the quartic Casimir of the QCD cusp anomalous dimension as an expansion for small cusp angle $ϕ$. This piece is gauge invariant, violates Casimir scaling, and first appears at four loops. It requires the evaluation of genuine non-planar four-loop Feynman integrals. We present results up to ${\mathcal O}(ϕ^4)$. One motivation for our calculation is to probe a recent conjecture on the all-order structure of the cusp anomalous dimension. As a byproduct we obtain the four-loop HQET wave function anomalous dimension for this color structur…
In recent years, many people have studied the possibility that the anomalous U(1) gauge symmetry is a trigger of SUSY breaking and/or an origin of the fermion mass hierarchy. Though it is interesting that the anomalous U(1) symmetry may explain these two phenomena simultaneously, it causes a negative stop mass squared or a severe fine-tuning in order to avoid the FCNC problem. Recently, it was pointed out that the F-term contribution of the dilaton field can dominate the flavor-dependent contribution from the anomalous U(1) D-term, so that the FCNC problem may be naturally avoided. In this pap…
Top quark physics at the LHC may open a window to physics beyond the standard model and even lead us to an understanding of the phenomenon "flavour". However, current flavour data is a strong hint that no "new physics" with a generic flavour structure can be expected in the TeV scale. In turn, if there is "new physics" at the TeV scale, it must be "minimally flavour violating". This has become a widely accepted assumption for "new physics" models. In this paper we propose a model-independent scheme to test minimal flavour violation for the anomalous charged $Wtq$, $q\in{d,s,b}$, and flavour-ch…
There exist experimental hints from the B sector for CP violation beyond the Standard Model (SM) CKM paradigm. An anomalous dimuon asymmetry was reported by the D0 collaboration, while tension exists between $B \to τν$ and $S_{ψK}$. These measurements, disfavoring the SM at the ~3$σ$ level, can be explained by new physics in both $B_d$-$\bar{B}_d$ and $B_s$- $\bar{B}_s$ mixing, arising from (1) new bosonic degrees of freedom at or near the electroweak scale, and (2) new, large CP-violating phases. These two new physics ingredients are precisely what is required for electroweak baryogenesis to …
We investigate the precisely measured anomalous magnetic moment and Lamb shift as tests for the possible existence of the radiatively induced Lorentz and CPT violation effects in quantum electrodynamics. To this end we calculate the one-loop vacuum polarization tensor and vertex radiative correction in dimensional reduction and on-shell renormalization scheme. We explicitly show how the Lorentz and CPT violation sector affects the anomalous magnetic moment and Lamb shift. Remarkably, we find infrared divergences coming from Lorentz and CPT violating term that do not cancel in physical cross se…
Electroweak vacuum transition processes (sphalerons) in the early Universe provide a possible explanation of the baryon asymmetry. Combining this physics with the anomalous commutators of Adler and Boulware and renormalization group invariance, we argue that electroweak baryon number violation also induces a ``topological condensate'' in the vacuum. QCD sphaleron processes act to distribute the baryon number violation between both left and right handed quarks and induce a spin independent component in this ``condensate''.
We establish a correspondence between those Feynman diagrams in the MSSM which give supersymmetric contributions to the muon anomalous magnetic moment and those which contribute to the flavor violating processes $μ--> eγ$ and $τ--> μγ$. Using current experimental limits on the branching ratios of these decay modes, combined with the assumption of a supersymmetric contribution to the muon anomalous magnetic moment, we establish bounds on the size of the lepton flavor violating soft masses in the MSSM largely independent of assumptions about other supersymmetric parameters. If the deviation meas…
We give a thorough analysis of the correlation between the muon anomalous magnetic moment and the radiative lepton flavor violating (LFV) processes within the minimal supersymmetric standard model. We find that in the case when the slepton mass eigenstates are nearly degenerate, $δa_μ$, coming from SUSY contributions, hardly depends on the lepton flavor mixing and, thus, there is no direct relation between $δa_μ$ and the LFV processes. On the contrary, if the first two generations' sleptons are much heavier than the 3rd one, i.e., in the effective SUSY scenario, the two quantities are closely …
We address the question whether a violation of Lorentz symmetry can explain the tension between the measurement and the Standard-Model prediction of the anomalous magnetic moment of the muon ($(g-2)_μ$) and whether it can significantly impact the one of the electron ($(g-2)_{e}$). While anisotropic Lorentz-violating effects are, in general, expected to produce sidereal oscillations in observables, isotropic Lorentz violation in the charged-lepton sector could feed into $(g-2)_{e,μ}$. However, we find that this type of Lorentz violation, parametrised via a dim-4 field operator of the Standard-M…
