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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Measurement of the direct CP violating charge asymmetry in $B^\pm \rightarrow \mu^\pm \nu_\mu D^{0}$ decays

We present the first measurement of the CP violating charge asymmetry in B±→μ±νμD0 decays using the full Run II integrated luminosity of 10.4 fb-1 in proton-antiproton collisions collected with the D0 detector at the Fermilab Tevatron Collider. We measure a difference in the yield of B- and B+ mesons in these decays by fitting the reconstructed invariant mass distributions. This results in an asymmetry of AμD0=[-0.14±0.20]%, which is consistent with standard model predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Recent Tevatron Results on CP-Violation

Using their full Tevatron Run II data sets, the CDF and D0 Experiments present measurements of CP-violating asymmetries in the charmless decay of bottom baryons Lambda-b => p pi-, Lambda-b => p K-, and also for Bs0 => K- pi+, B0 => K+ pi-, Ds => phi pi, and for single muons and like-sign dimuons in p-pbar collisions. Except for the like-sign dimuon asymmetry, these asymmetry measurements are consistent with available predictions of the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Quantifying limits on CP violating phases from EDMs in supersymmetry

We revisit the calculation of the electron, neutron, and proton electric dipole moments (EDMs) in the constrained minimal supersymmetric standard model (CMSSM). The relatively large mass of the Higgs boson, m H ≃ 125 GeV coupled with the (as yet) lack of discovery of any supersymmetric particle at the LHC, has pushed the supersymmetry breaking scale to several TeV or higher. Though one might expect this decoupling to have relaxed completely any bounds on the two CP violating phases in the CMSSM (θ μ and θ A ), the impressive experimental improvements in the limits on the EDMs (particularly the electron EDM) still allow us to set constraints of order (0.01–0.1)π on θ A and (0.001–0.1)π on θ μ . We also discuss the impact of future improvements in the experimental limits on supersymmetric models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

The MOMENT to search for CP violation

In this letter, we analyze for the first time the physics reach in terms of sensitivity to leptonic CP violation of the proposed MuOn-decay MEdium baseline NeuTrino beam (MOMENT) experiment, a novel neutrino oscillation facility that would operate with neutrinos from muon decay. Apart from obtaining a sufficiently intense flux, the bottlenecks to the physics reach of this experiment will be achieving a high enough suppression of the atmospheric background and, particularly, attaining a sufficient level of charge identification. We thus present our results as a function of these two factors. We consider a very massive Gd-doped Water Cherenkov detector. We also find that MOMENT will be competitive with other currently planned future oscillation experiments if a charge identification of at least 80 % can be achieved at the same time that the atmospheric background can be suppressed by at least a factor of ten. We also find a large synergy of MOMENT with the current generation of neutrino oscillation experiments, T2K and NOvA, which significantly enhances its final sensitivity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Baryogenesis via leptonic CP-violating phase transition

Here, we propose a new mechanism to generate a lepton asymmetry based on the vacuum CP-violating phase transition (CPPT). This approach differs from classical thermal leptogenesis as a specific seesaw model, and its UV completion, need not be specified. The lepton asymmetry is generated via the dynamically realised coupling of the Weinberg operator during the phase transition. This mechanism provides a connection with low-energy neutrino observables.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

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↗
DOE OSTI2020

$CP$ 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↗
DOE OSTI2013

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↗
DOE OSTI2018

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↗
DOE OSTI2014

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↗
DOE OSTI2013

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↗
DOE OSTI2015

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↗
DOE OSTI2021

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↗
DOE OSTI2012

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↗
DOE OSTI2013

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↗