Violation Of CPT Symmetry Research Articles

Lorentz- and CPT-violating neutrinos from string/D-brane model

We show that the space-time foam model from string/D-brane theory predicts a scenario in which neutrinos can possess linearly energy dependent speed variation, together with an asymmetry between neutrinos and antineutrinos, indicating the possibility of Lorentz and CPT symmetry violation for neutrinos. Such a scenario is supported by a phenomenological conjecture from the possible associations of IceCube ultrahigh-energy neutrino events with the gamma-ray bursts. It is also consistent with the constraints set by the energy-losing decay channels (e.g., e+e− pair emission, or neutrino splitting) upon superluminal neutrino velocities. We argue that the plausible violations of energy-momentum conservation during decay may be responsible for the stable propagation of these neutrinos, and hence for the evasion of relevant constraints.

Laser-assisted kaon decay and CPT symmetry violation

In this paper, we have investigated the charged kaons decay at the lowest order in the presence of a circularly polarized laser field. To be more precise, we have examined the leptonic decay of both positive (matter) and negative (antimatter) kaon which weakly decay via the exchange of W boson. Indeed, we have derived the expression of the leptonic decay width, the leptonic branching ratio, the leptonic ratio and the charged kaon lifetime by using the decay matrix approach. In addition, by using numerical computation, we have presented and discussed how the laser field influences these physical quantities. Moreover, we have analyzed the effect of the laser field on the parameter associated to the CPT symmetry. Then, we have concluded that, in the presence of an electromagnetic field and based on this CPT symmetry parameter, it is possible to control the dominance of matter over antimatter or vice-versa by applying an external field to either violate or conserve the CPT symmetry.

Particle–Antiparticle Asymmetry in Relativistic Deformed Kinematics

Relativistic deformed kinematics are usually considered a way to capture the residual effects of a fundamental quantum gravity theory. These kinematics present a non-commutative addition law for the momenta so that the total momentum of a multi-particle system depends on the specific ordering in which the momenta are composed. We explore in the present work how this property may be used to generate an asymmetry between particles and antiparticles through a particular ordering prescription, resulting in a violation of CPT symmetry. We study its consequences for muon decay, obtaining a difference in the lifetimes of the particle and the antiparticle as a function of the new high-energy scale, parameterizing such relativistic deformed kinematics.

Prospects for beyond the Standard Model physics searches at the Deep Underground Neutrino Experiment

The Deep Underground Neutrino Experiment (DUNE) will be a powerful tool for a variety of physics topics. The high-intensity proton beams provide a large neutrino flux, sampled by a near detector system consisting of a combination of capable precision detectors, and by the massive far detector system located deep underground. This configuration sets up DUNE as a machine for discovery, as it enables opportunities not only to perform precision neutrino measurements that may uncover deviations from the present three-flavor mixing paradigm, but also to discover new particles and unveil new interactions and symmetries beyond those predicted in the Standard Model (SM). Of the many potential beyond the Standard Model (BSM) topics DUNE will probe, this paper presents a selection of studies quantifying DUNE’s sensitivities to sterile neutrino mixing, heavy neutral leptons, non-standard interactions, CPT symmetry violation, Lorentz invariance violation, neutrino trident production, dark matter from both beam induced and cosmogenic sources, baryon number violation, and other new physics topics that complement those at high-energy colliders and significantly extend the present reach.

Testing CPT Symmetry with Neutral K Mesons: A Review

The neutral kaon system is a very peculiar system that offers unique possibilities to perform precise tests of the CPT symmetry. The entanglement of neutral kaon pairs that are produced at a ϕ-factory opens up new ways and scenarios in order to test this fundamental discrete symmetry. In this paper, the results of the most recent and significant CPT tests are reviewed. Experiments have set stringent limits on the CPT-violating parameters of different phenomenological models, some of them associated to possible decoherence mechanisms or Lorentz symmetry violation which might be justified in a quantum gravity framework. The present results show no violation of CPT symmetry, while their accuracy in some cases reaches the interesting level at which–in the most optimistic scenarios–quantum gravity effects might show up.

A possibility of CPT violation in the Standard Model

It is shown that there is a possibility of violation of CPT symmetry in the Standard Model which does not contradict the famous CPT theorem. To check this possibility experimentally it is necessary to increase the precision of measurements of the proton and antiproton mass difference by an order of magnitude.

Gravity, entanglement and CPT-symmetry violation in particle mixing

We study the probability oscillations of mixed particles in the presence of self gravitational interaction. We show that the presence of the parity leads to the violation of the time-reversal symmetry while the CP-symmetry is preserved hence inducing a CPT-symmetry violation. This violation is directly associated to the rising of the entanglement among the elements of the system that can be seen as a pure many-body effect scaling with the number of the elements in the system. This effect could have played a relevant role in the first stages of the universe or in core of very dense systems. Experiments based on Rydberg atoms confined in microtraps can simulate the mixing and the mutual interaction, and could allow to test the mechanism here presented.

Testing Lorentz invariance andCPTsymmetry using gamma-ray burst neutrinos

A recent work [Y. Huang and B.-Q. Ma, Commun. Phys. {\bf 1}, 62 (2018)] associated all four PeV neutrinos observed by IceCube to gamma-ray bursts (GRBs), and revealed a regularity which indicates a Lorentz violation scale $E_{\rm LV}=(6.5\pm0.4)\times10^{17}$ GeV with opposite sign factors $s=\pm 1$ between neutrinos and antineutrinos. The association of "time delay" and "time advance" events with neutrinos and antineutrinos (or vice versa) is only a hypothesis since the IceCube detector cannot tell the chirality of the neutrinos, and further experimental tests are needed to verify this hypothesis. We derive the values of the CPT-odd Lorentz violating parameters in the standard-model extension (SME) framework, and perform a threshold analysis on the electron-positron pair emission of the superluminal neutrinos (or antineutrinos). We find that different neutrino/antineutrino propagation properties, suggested by Y. Huang and B.-Q. Ma, can be described in the SME framework with both Lorentz invariance and CPT symmetry violation, but with a threshold energy constraint. A viable way on testing the CPT symmetry violation between neutrinos and antineutrinos is suggested.

Spontaneous CPT Violation and Quantum Anomalies in a Model for Matter–Antimatter Asymmetry in the Cosmos

We review scenarios of baryogenesis through leptogenesis at early epochs of the universe, in string-inspired minimal extensions of the Standard Model (SM), involving heavy right-handed Majorana neutrinos. Spontaneous violation of CPT symmetry is induced by appropriate (in general, temperature-dependent) backgrounds of the Kalb–Ramond (KR) axion field, which has its origins in the (bosonic) massless string multiplet. As interesting features of the model, we also discuss two issues associated with quantum (chiral) anomalies: (i) the non-contribution of the KR axion background to the (anomalous) chiral magnetic effect, which arises in the presence of external electromagnetic fields and non-zero chiral chemical potentials of charged fermions; and (ii) the potential role of quantum fluctuations of the KR axion on the (anomalous) radiative generation of a Majorana mass for the right-handed neutrinos themselves.

Tests of Lorentz Symmetry in the Gravitational Sector

Lorentz symmetry is one of the pillars of both General Relativity and the Standard Model of particle physics. Motivated by ideas about quantum gravity, unification theories and violations of CPT symmetry, a significant effort has been put the last decades into testing Lorentz symmetry. This review focuses on Lorentz symmetry tests performed in the gravitational sector. We briefly review the basics of the pure gravitational sector of the Standard-Model Extension (SME) framework, a formalism developed in order to systematically parametrize hypothetical violations of the Lorentz invariance. Furthermore, we discuss the latest constraints obtained within this formalism including analyses of the following measurements: atomic gravimetry, Lunar Laser Ranging, Very Long Baseline Interferometry, planetary ephemerides, Gravity Probe B, binary pulsars, high energy cosmic rays, … In addition, we propose a combined analysis of all these results. We also discuss possible improvements on current analyses and present some sensitivity analyses for future observations.

CPT Symmetry and Its Violation

One of the most fundamental symmetries in physics is CPT invariance. This article reviews the conditions under which CPT symmetry holds by recalling two proofs of the CPT theorem: The original Lagrangian-based analysis and the more rigorous one in the context of axiomatic quantum field theory. The presentation of the proofs is followed by a discussion of the major physical implications that arise from CPT symmetry. Motivated by recent theoretical and experimental interest in CPT tests, various approaches to the violation of CPT symmetry are mentioned, and it is briefly discussed how they evade the CPT theorem. An attempt has been made to keep this work self-contained and at a level suitable for a wider readership by excising as many technical aspects as possible.

Search for Violations of Lorentz Invariance and CPT Symmetry in B_{(s)}^{0} Mixing.

Violations of CPT symmetry and Lorentz invariance are searched for by studying interference effects in B^{0} mixing and in B_{s}^{0} mixing. Samples of B^{0}→J/ψK_{S}^{0} and B_{s}^{0}→J/ψK^{+}K^{-} decays are recorded by the LHCb detector in proton-proton collisions at center-of-mass energies of 7 and 8TeV, corresponding to an integrated luminosity of 3 fb^{-1}. No periodic variations of the particle-antiparticle mass differences are found, consistent with Lorentz invariance and CPT symmetry. Results are expressed in terms of the standard model extension parameter Δa_{μ} with precisions of O(10^{-15}) and O(10^{-14}) GeV for the B^{0} and B_{s}^{0} systems, respectively. With no assumption on Lorentz (non)invariance, the CPT-violating parameter z in the B_{s}^{0} system is measured for the first time and found to be Re(z)=-0.022±0.033±0.005 and Im(z)=0.004±0.011±0.002, where the first uncertainties are statistical and the second systematic.

CPT and Lorentz symmetry tests with entangled neutral kaons at KLOE/KLOE-2

The KLOE experiment at the DAΦNE ϕ-factory located at the INFN Laboratory in Frascati, Italy collected data corresponding to 2.5 fb−1 of integrated luminosity. Neutral kaon pairs produced in ϕ-meson decays offer a unique possibility to perform tests of fundamental discrete symmetries. The entanglement of the two kaons is exploited to search for possible violation of CPT symmetry and Lorentz invariance in the context of the Standard-Model Extension (SME) framework. A new approach to the analysis of ϕ → KSKL → π+π−,π+π− events has been adopted allowing us to independently measure all four CPT violating parameters Δaμ appearing for neutral kaons in the SME. The final KLOE results on Δaμ will be presented. These are presently the most precise measurements in the quark sector of the SME.

Test of CPT and Lorentz symmetry in entangled neutral kaons with the KLOE experiment

Neutral kaon pairs produced in ϕ decays in anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis of the CP-violating process ϕ→KSKL→π+π−π+π− based on 1.7 fb−1 of data collected by the KLOE experiment at the Frascati ϕ-factory DAΦNE. The data are used to perform a measurement of the CPT-violating parameters Δaμ for neutral kaons in the context of the Standard Model Extension framework. The parameters measured in the reference frame of the fixed stars are:Δa0=(−6.0±7.7stat±3.1syst)×10−18 GeV,ΔaX=(0.9±1.5stat±0.6syst)×10−18 GeV,ΔaY=(−2.0±1.5stat±0.5syst)×10−18 GeV,ΔaZ=(3.1±1.7stat±0.5syst)×10−18 GeV. These are presently the most precise measurements in the quark sector of the Standard Model Extension.

SEARCH FOR CPT AND LORENTZ INVARIANCE VIOLATION IN NEUTRAL KAONS AT KLOE/KLOE–2

Measurement of the difference of the decay times of neutral kaon pairs produced in an antisymmetric entangled state allows for the search of possible violation of CPT symmetry and Lorentz invariance. In this paper we present the recently announced results based on the reaction ϕ → KSKL → π+π-π+π- measured at the KLOE experiment. Obtained parameters in the Standard Model Extension (SME) are: [Formula: see text]

Polarization effects in the Higgs boson decay toγZand test ofCPandCPTsymmetries

Polarization characteristics of gamma gamma and gamma Z states in the Higgs boson decays h -> gamma gamma and h -> gamma Z are discussed. Based on effective Lagrangian, describing h gamma gamma and h gamma Z interactions with CP-even and CP-odd parts, we calculate polarization parameters xi_1, xi_2, xi_3. A nonzero value of the photon circular polarization, defined by parameter xi_2, arises due to presence of both parts in effective Lagrangian and its non-Hermiticity. The circular polarization is proportional to the forward-backward asymmetry of fermions in the decay h -> gamma Z -> gamma f bar{f}. Measurement of this observable would allow one to search for deviation from the standard model and possible violation of CPT symmetry. We discuss also a possibility to measure parameters xi_1, xi_3, describing correlation of linear polarizations of photon and Z boson, in the decay h -> gamma* Z -> l+ l- Z via distribution over the azimuthal angle between the decay planes of gamma* -> l+ l- and Z -> f bar{f}. Deviation of the measured value of xi_1 from zero will indicate CP violation in the Higgs sector.

Violation of CPT Invariance in the Early Universe and Leptogenesis/Baryogenesis

In this talk, I review some plausible scenarios entailing violation of CPT symmetry in the early Universe, due to space-time backgrounds which do not respect some of the assumptions for the validity of the CPT theorem (here considered will be Lorentz invariance and/or Unitarity). The key point in all these models is that the background induces different populations of fermions as compared to antifermions, and hence CPT Violation (CPTV), already in thermal equilibrium. Such populations may freeze out at various conditions depending on the details of the underlying microscopic model, thereby leading to leptogenesis and baryogenesis. Among the considered scenarios is a stringy one, in which the CPTV is associated with a cosmological background with torsion provided by the Kalb-Ramond antisymmetric tensor field (axion) of the string gravitational multiplet. We also discuss briefly (Lorentz Violating) CPTV models that go beyond the local effective lagrangian framework, such as a stochastic Finsler metric and D-particle foam. In the latter, the CPTV is induced by the interactions of stringy matter with populations of stochastically fluctuating point-like space-time defects (D-particles) that can be encountered in string/brane Cosmologies. The preferential rôle of neutrinos is singled out in this latter scenario as a consequence of gauge symmetry (charge) conservation.

Perspectives on Lorentz and CPT Symmetry Violation

Lorentz and CPT symmetries are fundamental to our understanding of the standard model and general relativity, but there has recently been a great deal interest in the possibility that they may not be exact in nature. There is a systematically developed effective field theory, the standard model extension, that describes such symmetry violations. Many types of experiments have been used to place constraints on the parameters characterizing this theory. Some of the best constraints come from high-energy astrophysics. Observations of the radiation from ultrarelativistic electrons make it possible to map out the electron energy-momentum relation with great precision. Using observations of synchrotron and inverse Compton emissions from a variety of sources, the coefficients for spin-independent Lorentz violation in the electron sector can be constrained at the 10−15−10−20 levels.

Induced Chern-Simons-like action in Lorentz-violating massless QED

In the present work, we study different aspects of Lorentz and CPT symmetry violation in extended massless QED. By following the observation that the 2+1-dimensional Maxwell-Chern-Simons theory can be originated from the 3+1-dimensional Chern-Simons-like action, we also focus on the fermion sector to relate the 3+1 dimensional extended massless QED to 2+1-dimensional massive QED. We take advantage of this to state that the Chern-Simons-like action in extended massless QED can be induced with its coefficient being well defined and finite just as its 2+1 counterpart. We make use of three different regularization schemes by inducting the Chern-Simons-like term in 3+1 dimensions to support the conjecture.

A Non-Abelian, Categorical Ontology of Spacetimes and Quantum Gravity

A non-Abelian, Universal SpaceTime Ontology is introduced in terms of Categories, Functors, Natural Transformations, Higher Dimensional Algebra and the Theory of Levels. A Paradigm shift towards Non-Commutative Spacetime structures with remarkable asymmetries or broken symmetries, such as the CPT-symmetry violation, is proposed. This has the potential for novel applications of Higher Dimensional Algebra to SpaceTime structure determination in terms of universal, topological invariants of ‘hidden’ symmetry. Fundamental concepts of Quantum Algebra and Quantum Algebraic Topology, such as Quantum Groups, von Neumann and Hopf Algebras are first considered with a view to their possible extensions and future applications in Quantum Field theories. New, non-Abelian results may be obtained through Higher Homotopy, General van Kampen Theorems, Lie Groupoids/Algebroids and Groupoid Atlases, possibly with novel applications to Quantum Dynamics and Local-to-Global Problems, Quantum Logics and Logic Algebras. Many-valued Logics, Łukasiewicz–Moisil Logics lead to Generalized LM-Toposes as global representations of SpaceTime Structures in the presence of intense Quantum Gravitational Fields. Such novel representations have the potential to develop a Quantum/General Relativity Theory in the context of Supersymmetry, Supergravity, Supersymmetry Algebras and the Metric Superfield in the Planck limit of spacetime. Quantum Gravity and Physical Cosmology issues are also considered here from the perspective of multiverses, thus leading also to novel types of Generalized, non-Abelian, Topological, Higher Homotopy Quantum Field Theories (HHQFT) and Non-Abelian Quantum Algebraic Topology (NA-QAT) theories.