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In this talk I review how to search for CP violation in top-quark pair production and decay using T-odd correlations. I discuss two examples which illustrate many of the relevant features: CP violation in a heavy neutral Higgs boson; and CP violating anomalous top-quark couplings. I present some numerical results for the LHC and some for the Tevatron.
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In order to observe a signal of possible CP violation in top-quark couplings, we study top-quark production and decay under the conditions of the Tevatron upgrade. Transverse energy asymmetries sensitive to CP violation are defined. Applying the recently proposed optimal method, we calculate the statistical significance for the direct observation of CP violation in the production and subsequent decay of top quarks.
We analyse the quark mass hierarchy and CKM matrix using the universal Yukawa coupling model with small violations precisely. We estimate the ranges of the values of 8 violation parameters (delta1u, delta2u, delta3u, delta1d, delta2d, delta3d, phi2, phi3) in our quark mass matrices satisfying quark mass ratios and CKM matrix, where phi2, phi3 are phases. Without these phases, the solution satisfying quark mass ratios and CKM matrix is not obtained. These parameters obtained can explain the CP violation effects.
I present some comments on the relationship between the small-$x$ behaviour of the parton (quark and gluon) densities and the scaling violation of the proton structure function $F_{2}(x,Q^{2})$.
CP violation in the CKM mixing for degenerate quark masses
本文研究了夸克质量近似简并时CKM混合中的CP破坏，发现简并对称性在其中起非平庸作用，并利用minimal flavor structure model阐明了质量层级与CP破坏的关系，为理解其起源和构建味模型提供帮助。
Unitarity of the Cabibbo-Kobayashi-Maskawa matrix gives rise to nine new unitarity triangles in the standard model.
We investigate the implications of $R$-Parity violation (RPV) for quark flavour violation both by constraining the sneutrino masses to be positive and by studying the processes $b\to sγ$ and $K^0-\bar K^0$ mixing. In the latter there are two major contributions, one from ``direct'' one loop diagrams involving RPV couplings, and one from the ``indirect'' contributions generated by the renormalisation group. We compare the effects and discuss the implications of our results.
We analyse the strength of CP violation in an extension of the standard model with an extra $Q=-1/3$ vector-like singlet quark, in the framework of the hypothesis of universality of strength of Yukawa couplings connecting standard quarks. We show that the correct pattern of quark masses and mixing can be obtained, including the observed strength of CP violation.
We present a review of general picture in the sector of electroweak symmetry breaking with the CP-violation in the heavy quark interactions.
We examine the violation of the kT factorization approximation for quark production in high energy proton-nucleus collisions. We comment on its implications for the open charm and quarkonium production in collider experiments.
Signals for Lorentz and CPT violation can appear in a wide range of experiments including hadron colliders like the LHC. We present a calculation of the Lorentz-violating cross section for top-quark pair production via gluon fusion. This process dominates at the LHC, and analysis of LHC data should permit sharpening the constraints on top-quark Lorentz violation obtained recently by the D0 Collaboration. We also present a separate calculation of single-top production, which is sensitive to CPT violation. Data from the LHC can be used to measure coefficients for CPT violation in the top-quark s…
A democratic form version of the Rosner-Worah quark mass matrix is discussed from a phenomenological point of view. It is pointed out that an ansatz of "maximal CP violation" can provide reasonable values of the Kobayashi-Maskawa mixings.
Duality is not violated at order Delta/M once j=3/2 and j=1/2+ states are properly accounted for.
A simple breaking of the subnuclear democracy among the quarks leads to a mixing between the second and the third family, in agreement with observation. Introducing the mixing between the first and the second family, one finds an interesting pattern of maximal CP-violation as well as a complete determination of the elements of the CKM matrix and of the unitarity triangles.
In view of the observed strong hierarchy of quark masses, we discuss a new description of flavor mixing which is particularly suited for models of quark mass matrices based on flavor symmetries. The necessary and sufficient conditions for CP violation are clarified. The emergence of CP violation is primarily linked to a large phase difference (near 90^{\circ}) in the light quark sector. The unitarity triangle is determined by the mass ratios of the light quarks. We conclude that the unitarity triangle should be close or identical to a rectangular triangle, and CP violation is maximal in this s…
On CP-violation and quark masses: reducing the number of free parameters
本文研究了CP破坏对夸克质量矩阵参数的影响，通过减少自由参数数量来揭示夸克质量本征值的相互关联性。
The standard electroweak final-state interaction induces a false T-odd correlation in the top-quark semileptonic decay. The correlation parameter is calculated in the standard model and found to be considerably larger than those that could be produced by genuine T-violation effects in a large class of theoretical models.
Parity violation induced by the chromo-anapole form factor of the bottom quark, generated from weak corrections, is studied in polarized hadron collisions. The forward-backward asymmetry in the bottom quark pair production at polarized $pp$ and $p\bar{p}$ colliders is evaluated in the Standard Model and in a Two Higgs Doublet Model to examine the effects of parity violation. In the models studied, promising results are found for polarized $p\bar{p}$ colliders.
Minimal Flavor Violation in the up-type quark sector leads to particularly interesting phenomenology due to the interplay of flavor physics in the charm sector and collider physics from flavor changing processes in the top sector. We study the most general operators that can affect top quark properties and $D$ meson decays in this scenario, concentrating on two CP violating operators for detailed studies. The consequences of these effective operators on charm and top flavor changing processes are generically small, but can be enhanced if there exists a light flavor mediator that is a Standard …
A simple breaking of the subnuclear democracy of the quarks leads to a mixing between the secons and the third family, in agreement with observation. Introducing the mixing between the first and the second family, one finds an interesting pattern of maximal CP-violation as well as complete determination of the elements of the CKM matrix and of the unitarity triangle.
The phenomenology of the five independent sets of $3\times 3$ quark mass matrices with five texture zeros is carried through in full detail, including predictions for the CP violation asymmetries. Our study is done without any approximation, first analytical and then numerical.
Violations of the Lorentz and CPT symmetries can appear as observable effects in the direct production of top quarks and their subsequent decays. Earlier results for the $q\bar{q}$ production process for $t\bar{t}$ pairs have been extended to include the gluon fusion process which dominates at the LHC. In addition results are obtained for testing CPT symmetry through single top quark production.
Flavor mixing and the quark mass spectrum are intimately related. In view of the observed strong hierarchy of the quark and lepton masses and of the flavor mixing angles it is argued that the description of flavor mixing must take this into account. One particular interesting way to describe the flavor mixing emerges, which is particularly suited for models of quark mass matrices based on flavor symmetries. We conclude that the unitarity triangle important for $B$ physics should be close to or identical to a rectangular triangle. $CP$ violation is maximal in this sense.
It is argued taking into account the observed mass spectra of the leptons and quarks that the phenomenon of flavor mixing is intimately related to the mass spectra. We discuss a particularly interesting way to describe the flavor mixing which is particularly suited for models of quark mass matrices based on flavor symmetries. CP violated is maximal or class to being maximal in our approach.
A pattern of quark mass hierarchy and CP violation within the framework of low energy supersymmetry is described. By assuming some discrete symmetry among the three families, the quarks of the third family obtain masses at tree level. The second family obtains masses radiatively at one-loop level due to the soft breaking of the family symmetry. At this level, the first family remains massless by some degeneracy conditions of the squarks. As a result of R-parity violation, the sneutrino vacuum expectation values are nonvanishing. CP violation occurs through the superweak sneutrino exchange. Thi…
We discuss the generalization of the Jarlskog condition of CP conservation for the case of the Standard Model with 4~quark generations. We express this condition in terms of the 3 Jarlskog invariants of the CKM matrix. Next we present the test for the existence of the 4-th quark generation in terms of the Jarlskog invariants involving only known particles.
The leading weak corrections to the production of top quark pairs via $q\bar{q} \to t\bar{t}$ in $p\bar{p}$ collisions are evaluated. The chromo-anapole form factor of the top quark and effects of parity violation are studied in the Standard Model (SM) and the Minimal Supersymmetric Model (MSSM). The parity violation effect in $q\bar{q} \to g \to t\bar{t}$ from the SM weak corrections is found to be very small. In the MSSM, the effects of parity violation can be enhanced for $\tanβ\equiv v_2/v_1 > \sqrt{m_t/m_b}$.
The supersymmetric one-loop contribution to the quark-lepton universality violation in the low-energy charged current weak interactions is studied. It is shown that the recent experimental data with the 1-$σ$ deviation from the universality may be explained by the existence of the light sleptons ($<220$GeV) and relatively light chargino and neutralinos ($<600$GeV) with significant gaugino components. The sign of the universality violation is briefly discussed.
Some aspects are considered on the flavor-nonconservation and $ CP $-violation arising from the quark mixings with singlet quarks. In certain models incorporating the singlet quarks, the contributions of the quark couplings to the neutral Higgs fields may become more significant than those of the neutral gauge interactions. Then, they would provide distinct signatures for new physics beyond the standard model in various flavor-nonconserving and $ CP $-violating processes such as the neutron electric dipole moment, $ D^0 $-$ {\bar D}^0 $, $ K^0 $-$ {\bar K}^0 $, $ B^0 $-$ {\bar B}^0 $, $ b \to …
The observed hierarchy of the quark masses is interpreted as a signal for an underlying ``subnuclear democracy'' as the relevant symmetry of the quark mass terms. A simple breaking of the symmetry leads to a mixing between the second and the third family, in agreement with observation. Introducing the mixing between the first and the second family, one finds an interesting pattern of maximal CP--violation as well as a complete determination of the elements of the CKM matrix and of the unitarity triangle.
Quark-sector Lorentz violation in $Z$-boson production
该研究利用Drell–Yan双轻子产生中$Z$玻色子交换的宇称破缺和自旋相关效应，基于LHC数据约束前两代夸克的CPT-even Lorentz破缺系数。
We present a model for quark masses and mixing, featuring geometrical CP violation through a Δ(27) triplet. By employing a single U(1)_F or Z_N symmetry in addition to Δ(27), we forbid all terms in the scalar potential that would spoil the calculable phases the triple acquires. The quark sector is realised by mimicking an existing scheme that reproduces the masses and CKM mixing, with the extra symmetry enabling the hierarchies in the Yukawa couplings through a Froggatt-Nielsen mechanism.
We find that the one-loop correction to the ratio of Yukawa coupling and gauge coupling in the gauge-Higgs unification, "gauge-Yukawa universality violation", is finite and calculable in any space-time dimension. Applying this result to the ratio of top quark and W-boson masses, we show that the order one correction required to generate a viable top quark mass is indeed possible if the fermion embedding top quark belongs to the large dimensional representation of the gauge group and a vacuum expectation value of Higgs scalar field is very small comparing to the compactification scale.
We review the historical developments leading to the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix. Present status of the CKM matrix from direct measurements is summarized, giving also the present profile of the unitarity triangle. CP Violation in the $K^0$ - $\bar{K^0}$ complex and in $B$-meson decays are discussed in the context of the CKM matrix.
We show that new physics models without new flavor violating interactions can explain the recent anomalies in the $b\to s\ell^+\ell^-$ transitions. The $b\to s\ell^+\ell^-$ arises from a $Z'$ penguin which automatically predicts the $V-A$ structure for the quark currents in the effective operators. This framework can be realized either in a renormalizable $U(1)'$ setup or be due to new strongly interacting dynamics. The di-muon resonance searches at the LHC are becoming sensitive to this scenario since the $Z'$ is relatively light, and could well be discovered in future searches by ATLAS and C…
Lorentz and CPT violation can affect the rates for $t$-$\ol t$ production and decay. The Lorentz-violating coefficients in the Standard-Model Extension responsible for modifying the top-quark events have recently been bounded by the D0 Collaboration. To extend the analysis to the LHC the calculations need to be extended to include the gluon fusion production mechanism. Some of the first results of this program were presented at the Meeting.
A detailed discussion based on exact calculations, possible in the non relativistic quark model, is given to show that there is no 1/m_Q term in the heavy quark expansion of totally integrated semileptonic decay rates. More generally, it is shown that OPE holds with very few terms in the expansion, at least in the harmonic oscillator model.
We discuss the quark mass matrices in the $A_4$ modular symmetry, where the $A_4$ triplet of Higgs is introduced for each up-quark and down-quark sectors, respectively. The model has six real parameters and two complex parameters in addition to the modulus $τ$. By inputting six quark masses and three CKM mixing angles, we can predict the CP violation phase $δ$ and the Jarlskog invariant $J_{CP}$. The predicted ranges of $δ$ and $J_{CP}$ are consistent with the observed values. The absolute value of $V_{ub}$ is smaller than $0.0043$, while $V_{cb}$ is lager than $0.0436$. In conclusion, our qua…
Flavor nonconserving and CP violating effects of the quark mixings are investigated in electroweak models incorporating singlet quarks. Especially, the D^0 - {\bar D}^0 mixing and the neutron electric dipole moment, which are mediated by the up-type quark couplings to the neutral Higgs fields, are examined in detail for reasonable ranges of the quark mixings and the singlet Higgs mass scale. These neutral Higgs contributions are found to be comparable to or smaller than the experimental bounds even for the case where the singlet Higgs mass scale is of the order of the electroweak scale and a s…
The prospects are explored for testing Lorentz and CPT symmetry in the top-quark sector. We present the relevant Lagrange density, discuss physical observables, and describe the signals to be sought in experiments. For top-antitop pair production via quark or gluon fusion with subsequent semileptonic or hadronic decays, we obtain the matrix element in the presence of Lorentz violation using the narrow-width approximation. The issue of testing CPT symmetry in the top-quark sector is also addressed. We demonstrate that single-top production and decay is well suited to a search for CPT violation,…
A scale-invariant "Gap Equation" is constructed for chiral quark $Q$ by Goldstone, or $V_L$, exchange, where massless input is guaranteed by gauge invariance. A numerical solution is found for Yukawa coupling $\sim 4π$. In turn, because this gap equation is scale invariant, the strong coupling solution is compatible with a 126 GeV dilaton, which would be a true messenger from higher energies. Some possible phenomena pertaining to heavy chiral quarks at few TeV scale is offered. Adding this heavy quark sector may provide enough CP violation for generating the matter dominance of the Universe.
In minimal supersymmetric model with a light Higgs sector, explicit CP violation and most general flavor mixings in the sfermion sector, integration of the superpartners out of the spectrum induces potentially large contributions to the Yukawa couplings of light quarks via those of the heavier ones. These corrections can be sizeable even for moderate values of tan(beta), and remain nonvanishing even if all superpartners decouple. Then Higgs boson couplings to light quarks assume spectacular enhancements; in particular, couplings to down and strange quarks become degenerate with that to the bot…
We explore the phenomenological quark-lepton mass matrices, which are devised following the S$_3$ flavour symmetry principle, yet fully consistent with SU(5) gauge models with the Higgs particles of {\bf 5}, {\bf 45} and their conjugates. The model contains 10 free parameters altogether. When 6 parameters are fixed by charge 2/3 quark and charged lepton masses, charge($-$1/3) quark masses and all quark mixing matrix elements are predicted to be close to experiment, leaving some narrow ranges still as freedom. Further specification of 3 more parameters (using, $m_d$, Cabibbo angle and $|V_{cb}|…
A D_5 Model of Quarks with Explicit CP Violation
本文研究具有精确D_5对称性的四希格斯二重态模型中的夸克部分，通过显式CP破坏框架下的数值拟合，成功再现了夸克质量谱和CKM混合矩阵，并验证了CP破坏来源。
Baryon octet magnetic moments when calculated within the chiral quark model, incorporating the orbital angular momentum as well as the quark sea contribution through the Cheng-Li mechanism, not only show improvement over the non relativistic quark model results but also gives a non zero value for the right hand side of Coleman-Glashow sum rule. When effects due to spin-spin forces between constituent quarks as well as `mass adjustments' due to confinement are added, it leads to an excellent fit for the case of p, Σ^+, Ξ^o and violation of Coleman-Glashow sum rule, whereas in almost all the oth…
In this paper, we investigate the behavior of the heavy quark potential in the backgrounds with hyperscaling violation. The metrics are covariant under a generalized Lifshitz scaling symmetry with the dynamical Lifshitz parameter $z$ and hyperscaling violation exponent $θ$. We calculate the potential for a certain range of $z$ and $θ$ and discuss how it changes in the presence of the two parameters. Moreover, we add a constant electric field to the backgrounds and study its effects on the potential. It is shown that the heavy quark potential depends on the non-relativistic parameters. Also, th…
In this work we study the anomalous top quark-gluon couplings Chromoelectric Dipole Moment (CEDM) and Chromomagnetic Dipole Moment (CMDM) in a general THDM with CP violation. We find that this model provides an important contribution from the $Y_{tt}$ Yukawa coupling that needs to be taken into account. The CMDM and CEDM obtained are $-0.03<Δ\tilde{k} < 0.005}$ and $|Δ\tilde{d}| < 0.005$, respectively.
We study supersymmetric models of lepton and baryon number violation based on an abelian family gauge group. Due to possible lepton-Higgs mixing, the lepton violating couplings are related to the Yukawa couplings and may be generated by them even if they were absent in the original theory. Such terms may be dominant and are not given by the naive family charge counting rules. This enhancement mechanism can provide an alignment between lepton-number violating terms and Yukawa couplings: as a result they conserve quark flavour. A natural way of suppressing baryon number violation in this class o…
The measurements of the neutrino and quark mixing angles satisfy the empirical relations called Quark-Lepton Complementarity. These empirical relations suggest the existence of a correlation between the mixing matrices of leptons and quarks. In this work, we examine the possibility that this correlation between the mixing angles of quarks and leptons originates in the similar hierarchy of quarks and charged lepton masses and the seesaw mechanism type~I, that gives mass to the Majorana neutrinos. We assume that the similar mass hierarchies of charged lepton and quark masses allows us to represe…
We found that in supersymmetric models with R-parity non-conservation the b-quarks may appreciably contribute to exotic neutrinoless muon-electron conversion in nuclei via the triangle diagram with two external gluons. This allowed us to extract previously overlooked constraints on the third generation trilinear R-parity violating parameters significantly more stringent than those existing in the literature.
The lepton or baryon number violating top quark interactions in the supersymmetric standard model with R parity violation contribute to the process d dbar to t tbar at the tree level via the t- or u-channel sfermion exchange. Since these interactions are chiral, they induce polarization to the top quark in the t tbar events at hadron colliders. We show in this article that the polarization can be a useful observable for probing these interactions at the upgraded Fermilab Tevatron collider, because the polarization is expected to be very small in the standard model.
We rewrite the Yukawa interactions of the standard model in terms of flavour-dependent vacuum structure to address the family mass hierarchy and CP violation in both the quark sector and lepton sector. It is realized for the first time that the Lagrangian only includes the same number of degrees of freedom as phenomenological observables with no requirement of extra particles or any new symmetry. The quark and lepton mass hierarchy arises as a natural result of the close-to-flat vacuum in flavour space. The CP violation in CKM and PMNS is explained as a general quantum phase between weak gauge…
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.
We find a minimal set of constraints which are independent of the choice of weak quark basis and necessary and sufficient for CP conservation for four quark families, including also the case of degenerate quark masses. These invariant conditions are written in the mass eigenstate basis as a function of the fermion masses and charged current mixings. CP violation is then related to the areas of three unitarity quadrangles and the CP violating effects of the fourth family are discussed in the case of small mixings.
We explore CP violating aspects in the Higgs sector of models where new vectorlike quarks carry Yukawa couplings mainly to the third generation quarks of the Standard Model. We point out that in the simplest model, Higgs CP violating interactions only exist in the hWW channel. At low energy, we find that rare B decays can place similarly strong constraints as those from electric dipole moments on the source of CP violation. These observations offer a new handle to discriminate from other Higgs CP violating scenarios such as scalar sector extensions of the Standard Model, and imply an interesti…
A properly defined and suitably broken $U(2)$ flavour symmetry leads to successful quantitative relations between quark mass ratios and CKM angles. At the same time the intrinsic distinction introduced by $U(2)$ between the third and the first two families of quarks and leptons may support anomalies in charged and neutral current semi-leptonic $B$-decays of the kind tentatively observed in current flavour experiments. We show how this is possible by the exchange of the $(3,1)_{2/3}$ vector leptoquark in two $U(2)$-models with significantly different values of Lepton Flavour Universality violat…
We calculate one-loop R-parity violating corrections to the top quark decay into a bottom quark and a polarized W-gauge boson. The corrections are presented according to the total corrections, the longitudinal corrections and the transverse corrections, respectively. We compared our results with the ${\cal O}(α_s)$ QCD corrections, the ${\cal O}(α)$ electroweak (EW) and finite width corrections, and also the supersymmetric (SUSY) corrections with R-parity conservation, respectively.
We study charged lepton flavor violation (CLFV) associated with heavy quark pair production in lepton-nucleon deep-inelastic scattering $\ell_i N \to \ell_j q\bar{q} X$. Here $\ell_i$ and $\ell_j$ denote the initial and final leptons; $N$ and $X$ are respectively the initial nucleon and arbitrary final hadronic system. We employ a model Lagrangian in which a scalar and pseudoscalar mediator generates the CLFV. We derive heavy quark structure functions for scalar and pseudoscalar currents and compute momentum distributions of the final lepton for the process. Our focus is on the heavy quark mas…
Angular and energy distributions for leptons and bottom quarks in the process e+e- --> t tbar --> l/b ... have been calculated assuming the most general top-quark couplings. The double distributions depend both on modification of the top-quark production and tbW decay vertices. However, the leptonic angular distribution turned out to be insensitive to non-standard parts of tbW vertex. The method of optimal observables have been used to estimate sensitivity of future measurements at linear e+e- colliders
We show that, if a fourth generation is discovered at the Tevatron or LHC, one could study CP violation in b' \to s decays. Asymmetries could reach 30% for b'\to sZ for m_{b'} \lesssim 350 GeV, while it could be greater than 50% for b'\to sγand extend to higher m_{b'}. Branching ratios are 10^{-3}--10^{-5}, and CPV measurement requires tagging. Once measured, however, the CPV phase can be extracted with little theoretical uncertainty.
We study a decay rate asymmetry of the top quark in the supersymmetric standard model, taking into account the constraints from the electric dipole moments of the neutron and the electron. One CP-violating phase contained in the mass-squared matrices of squarks and sleptons is allowed to have an unsuppressed value, even if their masses are of order 100 GeV. Sizable $CP$ violation could then occur in the production and decay of the top quark through interactions with top squarks. The asymmetry between the widths for the decays $t\to bW^+$ and $\bar t\to \bar bW^-$ can be of order $10^{-3}$, whi…
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