Problem Of CP Violation Research Articles

BAU Production in the SN-Breaking Standard Model

The violation of charge-parity symmetry and the baryon asymmetry of the universe are two of the most significant unresolved problems in physics. This article presents further research on the CP violation problem in the Standard Model with 32 candidate sets of the 10 “natural” parameters that exhibit the same Cabibbo–Kobayashi–Maskawa performance. These parameters are considered “natural” because they consist solely of the Yukawa couplings and the vacuum expectation value of the unique Higgs doublet in the Standard Model. Then, the problems of CP violation and the baryon asymmetry of the universe are investigated by using the Jarlskog measure of CP violation, ΔCP=J(mt2−mc2)(mt2−mu2)(mc2−mu2)(mb2−ms2)(mb2−md2)(ms2−md2)/T12, given that CP symmetry is violated following the breakdown of SN symmetries. Subsequently, numerical tests are performed in a simplified scenario where eight of the ten parameters are assumed to be fixed by two assumptions, and the remaining two parameters are allowed to vary from the S2-symmetric point (x,y)=(−1,1) to their current values in all 32 parameter sets. To estimate the enhancement of CP violation in such processes, a ratio RΔ≡ΔCP/ΔCP(0) is proposed between the running ΔCP and its current value, denoted by ΔCP(0), which is approximately 10−20. In all 32 cases, the three-dimensional plots of RΔ exhibit many regions that stick out of the RΔ=1010 plane, especially in regions very close to (x,y)=(−1,1). These results demonstrate that the SN-breaking Standard Model is already sufficient to violate CP symmetry explicitly and generate a significant amount of baryon asymmetry of the universe. Furthermore, it solves existing problems without creating new ones, at least in the scenario presented in this article.

Comparison of Different Searching Paradigms for Axion

An “invisible” matter called Dark Matter, which does not interact with the electromagnetic spectrum, is an idea to explain high velocity dispersion in the cluster and observed differences in mass to light ratio. Axion is the hypothetical particle that beyond the standard model, is suggested to resolve the Strong CP violation problem, its light mass enabling it to be a high potential candidate for cold dark matter, meanwhile explaining the violation in matter and antimatter. Therefore, multiple experiments include CAST, ADMX, MADMAX, XENON and ABRA but more than these are searching for different axion models, various axion masses and energy level sources, with theories such as Primakoff conversion. This article illustrates the latest limits for axion model base on ABRA results, with masses between 0.31neV to 8.3 neV, and the upper limit of gaγγ < 3.3×10-9 GeV-1 and < 1.4×10-10 GeV-1, no axion exists. Meanwhile, compared to other results given by CAST, masses range around 0.02 eV and gaγ up to 8.8×10-11 GeV-1 to gaγ larger or around 4×10-13 GeV-1 within the masses from 34.6771 to 34.6738 μeV. These results offer a better understanding of current axion models and research with latest achievements by comparing various detection methods and their observations.

Flavor and CP-violating Higgs sector in two Higgs doublet models with $$U(1)'$$

We investigate the role of a local $U(1)'$ symmetry for the problem of CP violation in the effective theory for two Higgs doublet models and its microscopic counterparts. First, in two Higgs doublet models with $U(1)'$, we show that the higher-dimensional operators in the scalar potential violate the CP symmetry with an interplay with the mixing mass parameter, giving rise to small mixings between CP-even and CP-odd scalars. Motivated by the $B$-meson anomalies in recent years, we take the flavored $U(1)'$ to be a benchmark model for specifying the flavor structure. Then, we calculate the electric dipole moment of electron (eEDM) at two loops due to the CP-violating higher-dimensional operators and identify the correlation between the masses of heavy Higgs bosons and the cutoff scale from the bound on eEDM. We also comment on the possibility of making an independent test of the CP violation in the collider searches for heavy Higgs bosons. Finally, we show how the obtained eEDM results in the effective theory can be used to constrain microscopic models with an explicit CP violation in the partially decoupled or dark sectors.

Dirac CP violation as a window to mass hierarchy in neutrino oscillation

Unresolved neutrino problems of mass hierarchy and CP violation have a more interesting interplay in neutrino phenomenology. Differing from the discrete symmetry approach, this issue is pursued from the perspective of neutrino oscillation with the matter effect. The contributions from and are entangled in a complex manner when the mass effect is considered. After investigating the role of in , it is found that at some determined values of , neutrino mass hierarchy can be determined at the same time. By introducing a statistical quantity λ, the requirement of distinguishable mass hierarchy and its confidence level can be investigated. The set of the values of forms a window for addressing mass hierarchy that is calculated for MINOS, NOνA and DUNE.

UCN source with superfluid helium at WWR-M reactor

The WWR-M reactor at PNPI is going to be equipped with an ultracold neutron source of high density. Method of UCN production is based on their accumulation in the super fluid helium due to particular qualities of that quantum liquid. The satisfying storage time of UCN at WWR-M reactor in the super fluid helium exists at a temperature below 1.2 K. Our source aims at obtaining a density of UCN equals to 104 n/cm3, two orders of magnitude exceeding that in existing sources presently available in the world. Increase in the density of UCN will raise the accuracy of the measurement of the neutron electric dipole moment (EDM) of an order of magnitude, which is fundamentally important for the problem of CP violation. The most intense sources of UCN allows PNPI become the centre of fundamental researches with ultracold neutrons.

Theory prospective on leptonic CP violation

The phenomenology of 3-neutrino mixing, the current status of our knowledge about the 3-neutrino mixing parameters, including the absolute neutrino mass scale, and of the Dirac and Majorana CP violation in the lepton sector are reviewed. The problems of CP violation in neutrino oscillations and of determining the nature – Dirac or Majorana – of massive neutrinos are discussed. The seesaw mechanism of neutrino mass generation and the related leptogenesis scenario of generation of the baryon asymmetry of the Universe are considered. The results showing that the CP violation necessary for the generation of the baryon asymmetry of the Universe in leptogenesis can be due exclusively to the Dirac and/or Majorana CP-violating phase(s) in the neutrino mixing matrix U are briefly reviewed. The discrete symmetry approach to understanding the observed pattern of neutrino mixing and the related predictions for the leptonic Dirac CP violation are also reviewed.

SUSY: Quo Vadis?

Given that there is currently no direct evidence for supersymmetric particles at the LHC it is timely to re-evaluate the need for low scale supersymmetry and to ask whether it is likely to be discoverable by the LHC running at its full energy. We review the status of simple SUSY extensions of the Standard Model in the light of the Higgs discovery and the non-observation of evidence for SUSY at the LHC. The need for large radiative corrections to drive the Higgs mass up to 126 GeV and for the coloured SUSY states to be heavy to explain their non-observation introduces a little hierarchy problem and we discuss how to quantify the associated fine tuning. The requirement of low fine tuning requires non-minimal SUSY extensions and we discuss the nature and phenomenology of models which still have perfectly acceptable low fine tuning. A brief discussion of SUSY flavour-changing and CP-violation problems and their resolution is presented.

Leptonic CP violation and leptogenesis

The phenomenology of 3-neutrino mixing, the current status of our knowledge about the 3-neutrino mixing parameters, including the absolute neutrino mass scale, and of the Dirac and Majorana CP violation in the lepton sector, are reviewed. The problems of CP violation in neutrino oscillations and of determining the nature — Dirac or Majorana — of massive neutrinos, are discussed. The seesaw mechanism of neutrino mass generation and the related leptogenesis scenario of generation of the baryon asymmetry of the universe, are considered. The results showing that the CP violation necessary for the generation of the baryon asymmetry of the universe in leptogenesis can be due exclusively to the Dirac and/or Majorana CP-violating phase(s) in the neutrino mixing matrix U, are briefly reviewed.

Tera-leptons’ shadows over Sinister Universe

The role of Sinister Heavy Fermions in Glashow’s SU(3) × SU(2) × SU(2)′ × U(1) model is to offer in a unique frame relic helium-like products (an ingenious candidate to the dark matter puzzle), a solution to the See-Saw mechanism for light neutrino masses as well as to the strong CP violation problem in QCD. The Sinister model requires three additional families of leptons and quarks, but only the lightest of them, the heavy U-quark and E-electron, are stable. Apparently the final neutral heliumlike (UUUEE) state is an ideal evanescent dark-matter candidate. However, it is reached by multi-body interactions in the early Universe along a tail of more manifest secondary frozen blocks. They should be now here polluting the surrounding matter. Moreover, in opposition to effective $$U\bar U$$ pair annihilation, there is no such an early or late tera-lepton pairs suppression because: (a) electromagnetic interactions are weaker than nuclear ones and (b) the primordial helium nucleus (4He)++ is able to attract and capture (in the first three minutes) E − fixing it into a hybrid tera-helium ion trap. This leads to a pile up of (4HeE −)+ traces, a lethal compound for any Sinister Universe. This capture leaves no tera-lepton frozen in (Ep) relic, otherwise an ideal catalyzer to achieve effective late E + E − annihilations, possibly saving the model. The (4HeE −)+ Coulomb screening is also avoiding the synthesis of the desired (UUUEE) hidden dark matter gas. The (4HeE −)+ E − behave chemically like an anomalous hydrogen isotope. Also terapositronium relics (e − E +) are over-abundant, and they behave like an anomalous hydrogen atom: these gases do not fit by many orders of magnitude the known severe bounds on hydrogen anomalous isotope, making shadows hanging over a Sinister Universe. However a surprising and resolver role for Tera-Pions in UHECR astrophysics has been revealed.

Study of CP violation in [formula omitted] decay at BES-III

In this Letter, we intend to study the problem of CP violation in D meson by D→VV decay mode in which the T violating triple-product correlation is examined. That would undoubtedly be another excellent probe of New Physics beyond Standard Model. For the neutral D, we focus on direct CP violation without considering D0–D¯0 oscillation. Experimentally, by a full angular analysis one may obtain such CP violating signals, and particularly it is worth mentioning that the upcoming large D data samples at BES-III in Beijing will provide a great opportunity to perform it.

Supersymmetric field theory in two-time physics

We construct N=1 supersymmetry in 4+2 dimensions compatible with the theoretical framework of 2T physics field theory and its gauge symmetries. The fields are arranged into 4+2-dimensional chiral and vector supermultiplets, and their interactions are uniquely fixed by supersymmetry (SUSY) and 2T-physics gauge symmetries. Many 3+1 spacetimes emerge from 4+2 by gauge fixing. Gauge degrees of freedom are eliminated as one comes down from 4+2 to 3+1 dimensions without any remnants of Kaluza-Klein modes. In a special gauge, the remaining physical degrees of freedom, and their interactions, coincide with ordinary N=1 supersymmetric field theory in 3+1 dimensions. In this gauge, SUSY in 4+2 is interpreted as superconformal symmetry SU(2,2|1) in 3+1 dimensions. Furthermore, the underlying 4+2 structure imposes some interesting restrictions on the emergent 3+1 SUSY field theory, which could be considered as part of the predictions of 2T-physics. One of these is the absence of the troublesome renormalizable CP violating F*F terms. This is good for curing the strong CP violation problem of QCD. An additional feature is that the superpotential is required to have no dimensionful parameters. To induce phase transitions, such as SUSY or electroweak symmetry breaking, a coupling to the dilaton is needed. This suggests amore » common origin of phase transitions that is driven by the vacuum value of the dilaton and needs to be understood in a cosmological scenario as part of a unified theory that includes the coupling of supergravity to matter. Another interesting aspect of the proposed theory is the possibility to utilize the inherent 2T gauge symmetry to explore dual versions of the N=1 theory in 3+1 dimensions, such as the minimal supersymmetric standard model (MSSM) and its duals. This is expected to reveal nonperturbative aspects of ordinary 1T field theory.« less

Nuclear electric dipole moments at ion storage rings

Upper limits on the electric dipole moments (EDM) of elementary particles and atoms are presented, and their physical implications are discussed. The implications following from the neutron and atomic experiments are of comparable interest. The nuclear EDMs can be studied at ion storage rings, with the expected sensitivity much better than $$10^{ - 24} \user1{e }{\text{cm}} $$ . This would represent a serious progress in studies of the CP-violation problem.

Renormalization of non-semisimple gauge models with the background field method

We study the renormalization of non-semisimple gauge models quantized in the 't Hooft-background gauge to all orders. We analyze the normalization conditions for masses and couplings compatible with the Slavnov-Taylor and Ward-Takahashi Identities and with the IR constraints. We take into account both the problem of renormalization of CKM matrix elements and the problem of CP violation and we show that the Background Field Method (BFM) provides proper normalization conditions for fermion, scalar and gauge field mixings. We discuss the hard and the soft anomalies of the Slavnov-Taylor Identities and the conditions under which they are absent.

What's new with the electroweak phase transition?

We review the status of non-perturbative lattice studies of the electroweak phase transition. In the Standard Model, the complete phase diagram has been reliably determined, and the conclusion is that there is no phase transition at all for the experimentally allowed Higgs masses. In the Minimal Supersymmetric Standard Model (MSSM), in contrast, there can be a strong first order transition allowing for baryogenesis. Finally, we point out possibilities for future simulations, such as the problem of CP-violation at the MSSM electroweak phase boundary.

Feasibility of search for nuclear electric dipole moments at ion storage rings

A sensitivity of much better than 10 −24 e cm may be expected in the searches for electric dipole moments (EDM) of β-active nuclei at ion storage rings. This would represent a serious progress in studies of the CP-violation problem.

Unconditional tests of fundamental discrete symmetries CP, T, CPT in rigorous quantum dynamics beyond the approximate Lee-Oehme-Yang theory

The CP-violation problem and unconditional tests of discrete symmetries T and CPT are investigated in the exact quantum theory (QT) beyond the usually used Lee-Oehme-Yang (LOY) theory, which is based on the famous Weisskopf-Wigner (WW) approximation. New unconditional CP-violation effects, independent from those known before, new unconditional tests of the CPT and T invariances, and new results for correlations are derived. Corresponding general results are obtained for\(K^0 - \bar K^0 ,{\mathbf{ }}B^0 - \bar B^0 ,{\mathbf{ }}D^0 - \bar D^0 \) mesons. On the base of these new theoretical results, some proposals for experiments by CP LEAR and ϕ, B factories are given. The new results are interesting not only for the CP-violation problem itself but also for testing violation of the standard quantum dynamics connected with ideas of quantum gravity.

Inverse neutrinoless double- beta decay in gauge theories with CP violation.

We investigate the reactions $e^-e^- \rightarrow W_i^-W_j^-$ for various gauge bosons production processes in the frame of the standard model with additional right-handed neutrinos and the Left-Right symmetric model. The present bounds on the various model parameters are taken into account. The question of the cross section behaviour for large energy and the CP violation problems are discussed.

CP violation in the heavy neutrino production process e+e--->N1N2.

The problem of CP conservation and CP violation for two heavy neutrinos production in $e^+e^-$ interaction is considered. Very convenient way of parametrization of the neutrino mass matrix, from which necessary and sufficient condition for CP conservation easily follows, is presented. Contrary to the Kobayashi-Maskawa mechanism, the effects of CP violation in the lepton sector with Majorana neutrinos can be very large. Change of the total cross section caused by CP violation can be much larger then the cross section itself.

Electroweak baryogenesis and dark matter via a gauge singlet scalar

We consider the possibility of using a gauge singlet scalar as the source of the additional CP violation needed to allow the observed baryon ( B) number asymmetry to be generated during the electroweak phase transition. In addition to extending the standard SU (3) × SU (2) × U (1) model by a gauge singlet scalar, it is also necessary to add additional fields, in order to transmit CP violation from the singlet scalar sector to the quarks and so to the B number violating processes in the early Universe. We consider the case of a second Higgs doublet, with Yukawa couplings to the quarks and leptons which are proportional to those of the standard model Higgs in order to avoid large FCNC effects. For reasonable values of the couplings of the gauge singlet scalar it is possible to generate the observed B asymmetry. A specific example is discussed for which we show that the singlet scalar expectation value goes to zero for temperatures below the electroweak phase transition temperature, allowing the model to avoid strong CP violation effects due to spontaneous CP violation and domain wall problems due to discrete symmetry breaking. In this case the singlet scalars are cosmologically stable and can naturally account for the cold dark matter in the Universe. Possible resolutions of the Higgs mass problem of electroweak baryogenesis within the framework of the model are also discussed.

Once more on the θ-vacua in (2 + 1)-dimensional QED and (3 + 1)-dimensional gluodynamics

Two different but tightly connected problems, the U(1) and strong CP violation problems, are discussed in two different models which exhibit both asymptotic freedom and confinement. One of them is the 3D Polyakov model of compact QED and the other is 4D gluodynamics. It is shown that, although both these models possess the long range interactions of the topological charges, only in the former case the physics does not depend on θ, while the latter exhibits an explicit θ dependence. The crucial difference is due to the observation that the pseudoparticles of 4D gluodynamics possess an additional quantum number, apart of the topological charge Q.