CP-Violating Coupling from a Quark Chromo-EDM
I will discuss progress in computing the long-range CP-violating pion-nucleon coupling that would arise from quark chromo-EDM BSM operators.
Walker-Loud, Andre↗
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CP violating anomalous couplings in Wy gamma and Zy gamma production at the LHC
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Study of the CP-violating effects with gg → Η → τ{sup +}τ{sup –} process
Study of the gg → Η → τ{sup +}τ{sup –} process was performed at Monte Carlo level within the framework of searching for CP-violating effects. The sensitivity of chosen observables to CP-parity of the Higgs boson was demonstrated for hadronic 1-prong τ decays (τ{sup ±} → π{sup ±}, ρ{sup ±}). Monte Carlo samples for the gg → Η → τ{sup +}τ{sup -} process were generated including the parton hadronisation to final state particles. This generation was performed for the Standard Model Higgs boson, the pseudoscalar Higgs boson, the Z → τ{sup +}τ{sup –} background, and mixed CP-states of the Higgs boson.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
$CP$ violation from $τ, t$ and $b$ dimension-6 Yukawa couplings — interplay of baryogenesis, EDM and Higgs physics
We explore the implications of the Standard Model effective field theory (SMEFT) with dimension-six terms involving the Higgs boson and third-generation fermion fields on the rate of Higgs boson production and decay into fermions, on the electric dipole moments (EDMs) of the electron, and on the baryon asymmetry of the Universe. We study the consequences of allowing these additional terms for each flavor separately and for combinations of two flavors. We find that a complex $\tau$ Yukawa coupling can account for the observed baryon asymmetry $Y_B^{\rm obs}$ within current LHC and EDM bounds. A complex $b$ ($t$) Yukawa coupling can account for $4\%$ ($2\%$) of $Y_B^{\rm obs}$, whereas a combination of the two can reach $12\%$. Combining $\tau$ with either $t$ or $b$ enlarges the viable parameter space owing to cancellations in the EDM and in either Higgs production times decay or the total Higgs width, respectively. Interestingly, in such a scenario there exists a region in parameter space where the SMEFT contributions to the electron EDM cancel and collider signal strengths are precisely SM-like, while producing sufficient baryon asymmetry. Measuring $CP$ violation in Higgs decays to $\tau$ leptons is the smoking gun for this scenario.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Possible evidence for the breakdown of the CKM-paradigm of CP-violation
Using primarily experimental inputs for S(B{sub d} {yields} {psi} K{sub s}), {Delta}M{sub B{sub s}}, {Delta}M{sub B{sub d}}, BR (B {yields} {tau}{nu}) and {epsilon}{sub K} along with necessary inputs from the lattice, we find that the measured value of sin(2{beta}) is smaller than expectations of the Standard Model by as much as 3.3 {sigma}, and also that the measured value of the BR(B {yields} {tau}{nu}) seems to be less than the predicted value by about 2.8 {sigma}. However, through a critical study we show that most likely the dominant source of these deviations is in B{sub d(s)} mixings and in sin(2{beta}) and less so in B {yields} {tau}{nu}, and also that the bulk of the problem persists even if input from {epsilon}{sub K} is not used. The fact that kaon mixing and {epsilon}{sub K} are not the dominant source of the deviation from the Standard Model has the very important consequence that model independent considerations imply that the scale of the relevant new CP-violating physics is below O(2 TeV), and possibly even a few hundred GeVs, thus suggesting that direct signals of the new particle(s) may well be accessible in collider experiments at the LHC and perhaps even at the Tevatron.
43 PARTICLE ACCELERATORS↗
Electromagnetic structure of the proton within the CP-violation hypothesis
The so-called non-Rosenbluth behavior of the proton electromagnetic form factors can be explained within the hypothesis of CP violation in electromagnetic processes involving composite systems of strongly interacting particles. It is shown that this hypothesis leads to the appearance of an additional, anapole, form factor of the proton. The proton electromagnetic form factors, including the anapole form factor, are estimated on the basis of experimental data on elastic electron-proton scattering.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
First measurement of the CP -violating phase $ {\phi}_s^{d\overline{d}} $ in B s o → (K + π – )(K – π + ) decays
A flavour-tagged decay-time-dependent amplitude analysis of B s o → (K + π – )(K – π + ) decays is presented in the K ± π ∓ mass range from 750 to 1600MeV/c 2 . The analysis uses pp collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0 fb –1 . Several quasi-two-body decay modes are considered, corresponding to K ± π ∓ combinations with spin 0, 1 and 2, which are dominated by the K o * (800)0 and K o * (1430) o , the K*(892) o and the K 2 * (1430) o resonances, respectively. The longitudinal polarisation fraction for the B 0 s → K*(892)°K¯*(892) 0 decay is measured as f L = 0.208 ± 0.032 ± 0.046, where the first uncertainty is statistical and the second is systematic. The first measurement of the mixing-induced CP -violating phase, $ {\phi}_s^{d\overline{d}} $, in b → dd¯s transitions is performed, yielding a value of $ {\phi}_s^{d\overline{d}} $ = –0.10 ± 0.13 (stat) ± 0.14 (syst) rad.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of indirect CP-violating asymmetries in D 0 →K + K - and D 0 →π + π - decays at CDF
We report a measurement of the indirect CP-violating asymmetries (A Γ ) between effective lifetimes of anticharm and charm mesons reconstructed in D 0 →K + K - and D 0 →π + π - decays. We use the full data set of proton-antiproton collisions collected by the Collider Detector at Fermilab experiment and corresponding to 9.7 fb -1 of integrated luminosity. The strong-interaction decay D *+ →D 0 π + is used to identify the meson at production as D 0 or D ¯0 . We statistically subtract D 0 and D ¯0 mesons originating from b-hadron decays and measure the yield asymmetry between anticharm and charm decays as a function of decay time. We measure A Γ (K + K - )=(-0.19±0.15(stat)±0.04(syst))%and A Γ (π + π - )=(-0.01±0.18(stat)±0.03(syst))%. The results are consistent with the hypothesis of CP symmetry and their combination yields A Γ =(-0.12±0.12)%.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of CP violation in $B_s^0\to J/\psi \phi$ decays using the full CDF data set
We report on the final measurement of the CP-violating $B_s^0$ mixing phase $\beta_s^{J/ψφ}$ in √s = 1.96 TeV proton-antiproton collisions collected with the Collider Detector at the Fermilab Tevatron collider. Using a sample corresponding to 9.6 fb -1 of integrated luminosity, we fit the decay-time evolution of $B_s^0$ → J/ψ (→ μ + μ - ) φ (→ K + K ₋ ) decays in which the b-quark content at production and the CP parity of the final state are identified. The interference of decays with and without mixing renders the $B_s^0$ mixing phase observable. The phase is determined to be -0.06 < $\beta_s^{J/ψφ}$ < 0.30 at 68% confidence level. The decay-width difference between heavy and light $B_s^0$ eigenstates, and the average $B_s^0$ lifetime are also determined to be ΔΓ s = 0.068 ± 0.027 ps -1 and $\tau_s$ = 1.528 ± 0.021 ps, respectively. These results are among the world’s most precise from a single experiment, and compatible with standard model predictions.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Contribution of relativistic quantum chemistry to electron’s electric dipole moment for CP violation
The search for the electric dipole moment of the electron (eEDM) is important because it is a probe of Charge Conjugation-Parity (CP) violation. It can also shed light on new physics beyond the standard model. It is not possible to measure the eEDM directly. However, the interaction energy involving the effective electric field (E{sub eff}) acting on an electron in a molecule and the eEDM can be measured. This quantity can be combined with E{sub eff}, which is calculated by relativistic molecular orbital theory to determine eEDM. Previous calculations of E{sub eff} were not sufficiently accurate in the treatment of relativistic or electron correlation effects. We therefore developed a new method to calculate E{sub eff} based on a four-component relativistic coupled-cluster theory. We demonstrated our method for YbF molecule, one of the promising candidates for the eEDM search. Using very large basis set and without freezing any core orbitals, we obtain a value of 23.1 GV/cm for E{sub eff} in YbF with an estimated error of less than 10%. The error is assessed by comparison of our calculations and experiments for two properties relevant for E{sub eff}, permanent dipole moment and hyperfine coupling constant. Our method paves the way to calculate properties of various kinds of molecules which can be described by a single-reference wave function.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Measurement of the CP-violating phase ϕs in the B s 0 → J / ψ ϕ ( 1020 ) → μ + μ − K + K − channel in proton-proton collisions at s = 13 TeV
The CP -violating weak phase ϕ s and the decay width difference Δ Γ s between the light and heavy B s 0 mass eigenstates are measured with the CMS detector at the LHC in a sample of 48 500 reconstructed B s 0 → J / ψ ϕ ( 1020 ) → μ + μ − K + K − events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4 fb − 1 , collected in proton-proton collisions at s = 13 TeV in 2017–2018. To extract the values of ϕ s and Δ Γ s , a time-dependent and flavor-tagged angular analysis of the μ + μ − K + K − final state is performed. The analysis employs a dedicated tagging trigger and a novel opposite-side muon flavor tagger based on machine learning techniques. The measurement yields ϕ s = − 11 ± 50 (stat) ± 10 (syst) mrad and Δ Γ s = 0.114 ± 0.014 (stat) ± 0.007 (syst) ps − 1 , in agreement with the standard model predictions. When combined with the previous CMS measurement at s = 8 TeV , the following values are obtained: ϕ s = − 21 ± 44 (stat) ± 10 (syst) mrad , Δ Γ s = 0.1032 ± 0.0095 (stat) ± 0.0048 (syst) ps − 1 , a significant improvement over the 8 TeV result.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of CP–Violating Asymmetries in $D^0 \to \pi^+ \pi^-$ and $D^0 \to K^+ K^- $ Decays at CDF
We report a search for non–Standard Model physics through the measurement of CP–violating asymmetries in the singly–Cabibbo– suppressed $D^0 \to \pi^+ \pi^-$ and $D^0 \to K^+ K^- $ decays reconstructed in about 5.9 fb-1 of CDF data. We use the strong $D^{*+} \to D^0\pi^+$ decay (“D tag”) to identify the flavor of the charmed meson at production time and exploit CP–conserving strong cc pair–production in pp collisions. Large samples of Cabibbo–favored $D^0 \to K^-\pi^+$ decays with and without D tag are used to highly suppress systematic uncertainties due to detector effects. The results are the world’s most precise measurements to date and have been published by Physical Review D in January 2012 [1].
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for CP-violating charge asymmetry in B{sup {+-}}{yields}J/{psi}K{sup {+-}} decays
We present the result of a search for charge asymmetry in B{sup {+-}}{yields}J/{psi}K{sup {+-}} decays using 772x10{sup 6} BB pairs collected at the {Upsilon}(4S) resonance by the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. The CP-violating charge asymmetry is measured to be A{sub CP}(B{sup +}{yields}J/{psi}K{sup +})=[-0.76{+-}0.50 (stat){+-}0.22 (syst)]%.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
CP violation studies in B mesons
The four general purpose detectors on the Tevatron (CDF, D0) and LHC (Atlas, CMS) hadron colliders continue to make important measurements in the field of CP violation (CPV) in B hadron physics. The CDF collaboration presents new results in direct CPV of charmless B decays, providing world-leading measurements in b baryon decays, and finding evidence for non zero CPV in the decayB_s^0 -> K^-pi^+. The D0 Collaboration presents measurements of the semileptonic mixing asymmetries in B^0 and B_s^0 mesons, with the former having a precision exceeding the previous world average. All four experiments perform time-dependent angular analysis of the decay B_s^0 -> J/psiphi enabling the extraction of the lifetime difference DeltaGamma_s and the CPV phasephi_s^J/psiphi. In all cases, the results obtained are consistent with each other, and with the standard model predictions.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Twenty-third Conference on Flavor Physics and CP Violation (FPCP 2025) at the University of Cincinnati
The High Energy Physics (HEP) group at the University of Cincinnati (UC) hosted the ``Twenty-third Conference on Flavor Physics and CP Violation'' (FPCP 2025), on June 2-6, 2025. The FPCP conference is one of the highest visibility conferences in flavor physics, drawing both theory and experimental participants from all over the world.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for $CP$ violation in D$^0$$\to$ K$^0_\mathrm{S}$K$^0_\mathrm{S}$ decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV
A search is reported for charge-parity $CP$ violation in D$^0$$\to$ K$^0_\mathrm{S}$K$^0_\mathrm{S}$ decays, using data collected in proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6 fb$^{-1}$, which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays D$^{*+}$$\to$ D$^0\pi^+$ and D$^{*-}$$\to$ D$^0\pi^-$. The $CP$ asymmetry in D$^0$$\to$ K$^0_\mathrm{S}$K$^0_\mathrm{S}$ is measured to be $A_{CP}$(K$^0_\mathrm{S}$K$^0_\mathrm{S}$) = (6.2 $\pm$ 3.0 $\pm$ 0.2 $\pm$ 0.8)%, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the $CP$ asymmetry in the D$^0$ $\to$ K$^0_\mathrm{S}\pi^+\pi^-$ decay. This is the first $CP$ asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the CP-violating phase phi sJ/psi phi using the flavor-tagged decay Bs(0) -> J/psi phi in 8 fb(-1) of p(p)over-bar collisions
We report an updated measurement of the CP-violating phase, {phi}{sub s}{sup J/{psi}{phi}} and the decay-width difference for the two mass eigenstates, {Delta}{Gamma}{sub s}, from the flavor-tagged decay B{sub s}{sup 0} {yields} J/{psi}{phi}. The data sample corresponds to an integrated luminosity of 8.0 fb{sup -1} accumulated with the D0 detector using p{bar p} collisions at {radical}s = 1.96 TeV produced at the Fermilab Tevatron collider. The 68% Bayesian credibility intervals, including systematic uncertainties, are {Delta}{Gamma}{sub s} = 0.163{sub -0.064}{sup +0.065} ps{sup -1} and {phi}{sub s}{sup J}/{psi}{phi} = -0.55{sub -0.36}{sup +0.38}. The p-value for the Standard Model point is 29.8%.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Charm Mixing, CP Violation and Rare D**0 Decays at BaBar
D{sup 0}-{bar D}{sup 0} mixing is expected to be small in the Standard Model. Several recent studies have shown evidence for this phenomenon. However, there has been no evidence for CP-violation, either in D{sup 0}-{bar D}{sup 0} mixing or direct D decays. We present evidence for D{sup 0}-{bar D}{sup 0} mixing and improved limits on CP asymmetries from the BABAR experiment. We also present new branching fraction measurements of radiative D decays and compare these measurements with theoretical predictions.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗