Charge-Parity-Time (CPT) symmetry governs that the oscillation parameters for neutrinos and anti-neutrinos are to be identical. Different mass and mixing parameters for these particles may give us a possible hint for CPT violation in the neutrino sector. Using this approach, we discuss the ability of long-baseline and atmospheric neutrino experiments to determine the difference between mass squared splittings ($Δm^{2}_{32}-Δ\bar{m}^{2}_{32}$) and atmospheric mixing angles ($\sin^{2}θ_{23}-\sin^{2}\barθ_{23}$) of neutrinos and anti-neutrinos. We show the joint sensitivity of the T2K, NOvA and INO experiments to such CPT violating observables in different possible combinations of octant for neutrinos and anti-neutrinos.
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}.
Tests of Lorentz invariance violation and CPT Violation in neutrino oscillations are discussed. The sensitivity of current and future experiments is presented.
The review covers transitions between M0 and M0bar in all four systems M0 = K0, D0, B0 and Bs. These systems are ideal laboratories for studying the discrete symmetries T and CPT. The properties of time reversal T are discussed in classical and quantum mechanics. T violation in K0 K0bar transitions has been observed in 1970 independent of assuming CPT symmetry by using the Bell-steinberger unitarity relation. Improvements of this observation are reviewed including the latest results in 2013. They show with high significance that CP violation in K0 K0bar transitions is only T violation without …
We have studied $CPT$ violation in neutrino oscillation considering three flavor framework with matter effect. We have constructed a new way to find the oscillation probability incorporating $CPT$ violating terms without any approximation. Then $CPT$ violation with atmospheric neutrinos for a magnetized iron calorimeter detector considering the muons (directly measurable with high resolution) of the charge current events has been studied for zero and nonzero $θ_{13}$ values. It is found that a potential bound of $δb_{32} \lapp 6\times 10^{-24}$ GeV at 99% CL can be obtained with 1 Mton.year ex…
A simple analysis of time-dependent $B_s\to K^+K^-$ transitions, based on recent results from the LHCb experiment, is presented. The benefits of adopting a fully consistent theoretical description of the $B^0_s$--$\bar B^0_s$ mixing are stressed. It is shown that bounds on CPT violation in the $B^0_s$--$\bar B^0_s$ system can be consistently obtained and that direct CP violation in $B_s\to K^+K^-$ can be robustly established, even in the presence of CPT violation in the mixing.
We discuss how a possible violation of the combined symmetry CPT in the B meson system can be investigated at the LHC. We show how a tagged and an untagged analysis of the decay modes of both B(d) and B(s) mesons can lead not only to a possible detection of a CPT-violating new physics but also to an understanding of its precise nature. The implication of CPT violation to a large mixing phase in the B(s) system is also discussed.
An analysis from the D0 Collaboration measuring the charge asymmetry A^b_sl of like-sign dimuon events due to semileptonic b-hadron decays at the Fermilab Tevatron Collider is described. It differs by 3.2 standard deviations from the Standard Model prediction to provide first evidence of CPT-invariant anomalous CP violation in the mixing of neutral B mesons, and is compared to the CP-violating phase obtained from a D0 analysis of the time-dependent decay angles in B0_s -> J/psi phi. If CPT violation is allowed, the dimuon asymmetry also yields the first sensitivity to CPT violation in the B0_s…
The conclusions summarize the main, but not all, aspects of a two-days workshop held at MITP Mainz. The four covered aspects are T violation in decays of neutral B mesons, T and CPT studies in B0B0bar transitions with Belle, future measurements of T violation in B and D decays, and direct tests of T and CPT symmetries in the entangled neutral Kaon system at a ?Phi factory.
The neutral kaon system offers a unique possibility to perform fundamental tests of CPT invariance. In this contribution the KLOE prospects for the measurements of CPT violation in the context of the Standard Model Extension are presented together with a full description of the analysis method needed and with the perspective given by the KLOE-2 data-taking campaign.
Recent measurements of CPT violation and Lorentz symmetry breaking in $B^0-\bar{B}^0$ mixing and $B^0_s-\bar{B}^0_s$ mixing, obtained from data taken by the LHCb experiment, are highlighted. The results are expressed in terms of the Standard-Model Extension (SME) coefficients, which incorporate both CPT and Lorentz violation. Due to the large boost of the $B$ mesons at LHCb, the SME coefficients can be determined with high precision. The bounds on these coefficients are improved significantly compared to previous measurements.
We show that new physics, either from CPT violation in B^0-\bar{B}^0 mixing or from ΔB = -ΔQ transitions, may lead to an opposite-sign dilepton asymmetry of neutral B-meson decays. Both effects have the same time-dependent behavior and therefore are in general indistinguishable from each other. We also clarify some ambiguity associated with the constraint on CPT violation in semileptonic decays of incoherent B^0 and \bar{B}^0 mesons.
A search is presented for CPT-violating effects in the mixing of $B^0_s$ mesons using the D0 detector at the Fermilab Tevatron Collider. The CPT-violating asymmetry in the decay $B^0_s \rightarrow μ^{\pm} D_s^{\mp} X$ as a function of sidereal phase is measured. No evidence for CPT-violating effects is observed and limits are placed on CPT- and Lorentz-invariance violating coupling coefficients.
The experimental signatures of nonstandard neutrino interactions are shown to be equivalent to CPT violation in neutrino oscillations. This result leads to a correspondence in the study of these two descriptions that can be used to constrain the relevant parameters of one formalism by using the available bounds on parameters of the other. The correspondence is illustrated and explicitly used to determine first bounds on previously unexplored parameters in both formalisms.
An overview of current experimental bounds on $CPT$ violation in neutral meson mixing is given. New values for the $CPT$ asymmetry in the $B^0$ and $B_s^0$ systems are deduced from published BaBar, Belle and LHCb results. With dedicated analyses, LHCb will be able to further improve the bounds on $CPT$ violation in the $D^0$, $B^0$ and $B_s^0$ systems. Since $CPT$ violation implies violation of Lorentz invariance in an interacting local quantum field theory, the observed $CPT$ asymmetry will exhibit sidereal- and boost-dependent variations. Such $CPT$-violating and Lorentz-violating effects ar…
We discuss some possible signals of CPT violation in the $B_s$ system that may be probed at the Large Hadron Collider (LHC). We show how one can construct combinations ofobservables coming from tagged and untagged decay rates of $B_s\to D_s^\pm K^\mp$ that can unambiguously differentiate between CPT violating and CPT conserving new physics (NP) models contributing in $B_s-\bar B_s$ mixing. We choose this particular mode as an illustrative example for two reasons: (i) In the Standard Model, there is only one decay amplitude, so it is easier to untangle any new physics; (ii) $B_s$ being a neutra…
The status of Lorentz- and CPT-violation searches using measurements of the anomalous magnetic moment of the muon is reviewed. Results from muon g-2 experiments have set the majority of the most stringent limits on Standard- Model Extension Lorentz and CPT violation in the muon sector. These limits are consistent with calculations of the level of Standard-Model Extension effects required to account for the current 3.7σ experiment-theory discrepancy in the muon's g-2. The prospects for the new Muon g-2 Experiment at Fermilab to improve upon these searches is presented.
Even though it is undoubtedly very appealing to interpret the latest T2K results as evidence of CP violation, this claim assumes CPT conservation in the neutrino sector to an extent that has not been tested yet. As we will show, T2K results are not robust against a CPT-violating explanation. On the contrary, a CPT-violating CP-conserving scenario is in perfect agreement with current neutrino oscillation data. Therefore, to elucidate whether T2K results imply CP or CPT violation is of utter importance. We show that, even after combining with data from NO$ν$A and from reactor experiments, no cla…
A D0 analysis measuring the charge asymmetry Ab_sl of like-sign dimuon events due to semileptonic b-hadron decays at the Fermilab Tevatron Collider has shown indications of possible anomalous CP violation in the mixing of neutral B mesons. This result has been used to extract the first senstivity to CPT violation in the B0_s system. A procedure to explore further this anomaly by specifically measuring the semileptonic charge asymmetry, as_sl, in B0_s decays is described, as well as how a variant of this analysis can be used to explore a larger set of CPT-violating parameters in the B0_s system…
A natural realization of CPT violation in neutrino oscillation can arise due to the coupling to a light scalar or vector dark matter (DM). The dark non-standard interaction (NSI) is associated with the $γ_0$ matrix in neutrino's effective propagator and hence corrects the neutrino Hamiltonian as dark matter potential, in the same way as the ordinary matter effect. The effect is, however, inversely proportional to the neutrino energy and hence appears as a correction to the neutrino mass squared. Due to a sign difference in the corrections for neutrino and anti-neutrino modes, the neutrino osci…
We study the sensitivity of the Iron Calorimeter (ICAL) at the India-Based Neutrino Observatory (INO) to Lorentz and CPT violation in the neutrino sector. Its ability to identify the charge of muons in addition to their direction and energy makes ICAL a useful tool in putting constraints on these fundamental symmetries. Using resolution, efficiencies, errors and uncertainties obtained from ICAL detector simulations, we determine sensitivities to $δ{b}_{31}$, which parametizes the violations in the muon neutrino sector. We carry out calculations for three generic cases representing mixing in th…
We first study how sterile neutrinos can fit the 5sigma bar-nu_mu --> bar-nu_e LSND anomaly: 2+2 solutions are strongly disfavoured by solar and atmospheric data, while 3+1 solutions can still give a poor fit (for a specific range of oscillation parameters, to be tested by MiniBooNE). If instead MiniBoone will find no nu_mu --> nu_e signal, we will have a hint for CPT violation. Already now, unlike sterile neutrinos, CPT-violating neutrino masses can nicely accomodate all safe and unsafe data. We study how much CPT must be conserved according to atmospheric and K2K data and list which CPT-viol…
Searches for Lorentz and CPT violation using neutrino oscillations and the prospects for future tests using neutrino time-of-flight measurements and beta-decay experiments are presented.
The spin precession frequency of muons stored in the $(g-2)$ storage ring has been analyzed for evidence of Lorentz and CPT violation. Two Lorentz and CPT violation signatures were searched for: a nonzero $Δω_{a}$ (=$ω_{a}^{μ^{+}}-ω_{a}^{μ^{-}}$); and a sidereal variation of $ω_{a}^{μ^{\pm}}$. No significant effect is found, and the following limits on the standard-model extension parameters are obtained: $b_{Z} =-(1.0 \pm 1.1)\times 10^{-23}$ GeV; $(m_μd_{Z0}+H_{XY}) = (1.8 \pm 6.0 \times 10^{-23})$ GeV; and the 95% confidence level limits $\check{b}_{\perp}^{μ^{+}}< 1.4 \times 10^{-24}$ GeV …
We comment on CP, T and CPT violation in the light of interesting new data from the CPLEAR and KTeV Collaborations on neutral kaon decay asymmetries. Other recent data from the CPLEAR experiment, constraining possible violations of CPT and the $ΔS = ΔQ$ rule, exclude the possibility that the semileptonic-decay asymmetry $A_{T}$ measured by CPLEAR could be solely due to CPT violation, confirming that their data constitute direct evidence for T violation. The CP-violating asymmetry in $K_L \to e^-e^+π^-π^+$ recently measured by the KTeV Collaboration does not by itself provide direct evidence fo…
We show that atmospheric neutrinos can provide a sensitive and robust probe of CPT violation (CPTV). We perform realistic event-rate calculations and study the variations of the ratio of total muon to antimuon survival rates with $L/E$ and $L$ ($L$ $\equiv$ baseline length, $E$ $\equiv$ neutrino energy) in a detector capable of identifying the muon charge. We demonstrate that measurements of these ratios when coupled with the significant $L$ and $E$ range which characterizes the atmospheric neutrino spectrum provides a method of both detecting the presence of such violations and putting bounds…
In this review I classify the possible ways of CPT violation, and I describe briefly their phenomenology, in both terrestrial and astrophysical experiments, including antimatter factories, neutral mesons and neutrinos, and discuss the various sensitivities. I also pay attention to disentangling genuine quantum-gravity induced CPT violation from `fake' violation due to ordinary matter effects. A particularly interesting situation arises when the breaking of CPT invariance is through unitarity violations, in the sense of the matter theory being viewed as an effective field theory, entangled with…
Recent measurements of observables sensitive to CPT, T and CP violation in neutral B meson mixing by the B-factory experiments Belle and BaBar are presented.
The LSND signal for \barν_μto \barν_e oscillations has prompted supposition that there may be a fourth light neutrino or that CPT is violated. Neither explanation provides a good fit to all existing neutrino data. We examine the even more speculative possibility that a four-neutrino model with CPT violation can explain the LSND effect and remain consistent with all other data. We find that models with a 3+1 mass structure in the neutrino sector are viable; a 2+2 structure is permitted only in the antineutrino sector.
A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on fifteen antiproton decay modes. The results are used to place limits on the characteristic mass scale Mx that could be associated with CPT-violation accompanied by baryon number violation.
We present an improved determination of the CP and CPT violation parameters Re(epsilon) and Im(delta) based on the unitarity condition (Bell-Steinberger relation) and on recent results from the KLOE experiment. We find Re(epsilon) = (159.6 \pm 1.3)10^-5 and Im(delta) = (0.4 \pm 2.1)10^-5, consistent with no CPT violation.
We present a new measurement constraining Lorentz and CPT violation of the proton using a hydrogen maser double resonance technique. A search for hydrogen Zeeman frequency variations with a period of the sidereal day (23.93 h) sets a clean limit on violation of Lorentz and CPT symmetry of the proton at the 10^{-27} GeV level.
We present two new measurements constraining Lorentz and CPT violation using the Xe-129 / He-3 Zeeman maser and atomic hydrogen masers. Experimental investigations of Lorentz and CPT symmetry provide important tests of the framework of the standard model of particle physics and theories of gravity. The two-species Xe-129 / He-3 Zeeman maser bounds violations of CPT and Lorentz symmetry of the neutron at the 10^-31 GeV level. Measurements with atomic hydrogen masers provide a clean limit of CPT and Lorentz symmetry violation of the proton at the 10^-27 GeV level.
Tilted brane in theories with large compact extra dimensions leads to spontaneous symmetry breaking of the Lorentz and rotational invariance in four dimensions, as shown by Dvali and Shifman. In this brief report, we point out that the mentioned Lorentz symmetry breaking, although leading to the CPT--violating interaction terms, cannot lead to the CPT violation in the experimentally interesting $K$--${\bar K}$ and analogous systems.
We show that, besides the usual short distance contribution for CP violation, final state interactions together with CPT invariance can play an important role in the recent observation of CP violation in three-body charmless $B^\pm$ decays. A significant part of the observed CP asymmetry distribution in the Dalitz plot is located in a region where hadronic channels are strongly coupled. We illustrate our discussion comparing the recent observation of CP violation in the $B^\pm\to K^\pm K^+ K^-$ and $B^\pm\to K^\pm π^+ π^-$ phase space, with a calculation based on $ππ\to KK$ scattering.
Using a more accurate approximation than that applied by Lee--Oehme--Yang we show that the interpretation of the tests measuring the difference between the $K_{0}$ mass and the ${\bar K}_{0}$ mass as the CPT--symmetry test is wrong. We find that in fact such tests are tests for the existence of the hypothetical interaction allowing the first order $|ΔS| = 2$ transitions $K_{0} \rightleftharpoons {\bar K}_{0}$.
Using data collected with the BaBar detector at PEP-II at SLAC, we report on several tau lepton measurements that are used to determine the modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vus, and to check the Standard Model predictions of lepton universality and CPT conservation.
We report results of a search for CPT and Lorentz violation in B0-B0bar oscillations using inclusive dilepton events from 232 million Y(4S) --> BBbar decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find 2.8sigma significance, compatible with no signal, for variations in the complex CPT violation parameter z at the Earth's sidereal frequency and extract values for the quantities Δ(a_μ) in the general Lorentz-violating standard-model extension. The spectral powers for variations in z over the frequency range 0.26/year to 2.1/day are also compatible with no signal.
Deviations from Lorentz and CPT invariance in the neutrino sector and their observable effects in double beta decay are studied. For two-neutrino double beta decay, a spectral distortion and its properties are characterized for different isotopes. Majorana couplings for Lorentz violation are studied and shown to trigger neutrinoless double beta decay even for negligible Majorana mass. Existing data are used to obtain first limits of $5 \times 10^{-9}$ for 18 individual coefficients and attainable sensitivities in current and future experiments are presented.
We consider CPT violation in neutrino sector, which is induced by ghost condensation. A model with extra dimension is suggested where ghost condensation occurs at a distant location separated from the SM brane. Right handed neutrinos in the bulk, which are originally introduced to explain small Yukawa couplings, play the role of messenger fields communicating ghost condensation and the standard model sector and lead to a sizable CPT violation in neutrino sector at the leading order. The model provides a resolution to the recent MINOS anomaly without spoiling any experimental constraints and ma…
A search for sidereal variations in the frequency difference between co-located 129-Xe and 3-He Zeeman masers sets the most stringent limit to date on leading-order Lorentz and CPT violation involving the neutron, consistent with no effect at the level of 10^{-31} GeV.
In this talk we present the perspectives about measurements of CP and CPT violating quantities at future Super Flavour Factories. In particular we will focus on the expected sensitivities reachable after 5 years of data taking with the SuperB detector: this dataset will allow to perform measurements on B meson, D meson and tau lepton systems with greatly enhanced precision over the current results.
We describe measurements of CP and CPT violation parameters in B^0B^0bar oscillations, performed at BaBar by using BBbar events collected at the Y(4S) mass peak. These are obtained from two different B-reconstruction methods, namely: searching for two inclusive semileptonic B^0 decays in an event or partially reconstructing one of the B^0 mesons in the D* l nu_l channel. The results are in agreement with one another and with the most recent theoretical calculations in the Standard Model scenario.
