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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Evidence for $CP$ violation and measurement of $CP$-violating parameters in B$^0_\mathrm{s}$ $\to$ J/$\psi\,\phi$(1020) decays in pp collisions at $\sqrt{s} =$ 13 TeV

A pioneering machine-learning-based flavor-tagging algorithm combining same-side and opposite-side tagging is used to obtain the equivalent of 27$\,$000 tagged B$^0_\mathrm{s}$$\to$ J/$\psi\, \phi$(1020) decays from pp collisions at $\sqrt{s} =$ 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 96.5 fb$^{-1}$. A time- and flavor-dependent angular analysis of the $\mu^+\mu^-$K$^+$K$^-$ final state is used to measure parameters of the $\mathrm{B}^0_\mathrm{s}$-$\overline{\mathrm{B}}^0_\mathrm{s}$ system. The weak phase is measured to be $\phi_\mathrm{s}$ = $-$73 $\pm$ 23 (stat) $\pm$ 7 (syst) mrad, which, combined with a $\sqrt{s}$ = 8 TeV CMS result, gives $\phi_\mathrm{s}$ = $-$74 $\pm$ 23 mrad. This value differs from zero by 3.2 standard deviations, providing evidence for $CP$ violation in B$^0_\mathrm{s}$$\to$ J/$\psi\,\phi$(1020) decays. All measured physics parameters are found to agree with standard model predictions where available.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Search for CP violation in D ± meson decays to Φπ±

We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP-violating asymmetries for the Cabibbo-suppressed decays D ± →K⁺ K⁻ π ± and the Cabibbo-favored decays D s ± → K⁺K⁻ π ± in the K⁺K⁻ mass region of the Φ resonance. Using 955 fb⁻¹ of data collected with the Belle detector, we obtain A CP D⁺ →Φπ⁺ = (+0.51±0.28±0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of 5.We find no evidence for direct CP violation.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2015

Asymmetric dark matter and CP violating scatterings in a UV complete model

We explore possible asymmetric dark matter models using CP violating scatterings to generate an asymmetry. In particular, we introduce a new model, based on DM fields coupling to the SM Higgs and lepton doublets, a neutrino portal, and explore its UV completions. We study the CP violation and asymmetry formation of this model, to demonstrate that it is capable of producing the correct abundance of dark matter and the observed matter-antimatter asymmetry. Crucial to achieving this is the introduction of interactions which violate CP with a T{sup 2} dependence.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Precise measurement of the CP violation parameter sin 2Φ 1 in B 0 → (c$\bar{c}$)K 0 decays

We present a precise measurement of the CP violation parameter sin2$\phi$ 1 and the direct CP violation parameter $A$ f using the final data sample of 772×10 6 $B\overline{B}$ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. One neutral B meson is reconstructed in a J/ψK$0\atop{S}$, ψ(2S)K$0\atop{S}$, χc1K$0\atop{S}$, or J/ψK$0\atop{L}$ CP eigenstate and its flavor is identified from the decay products of the accompanying B meson. From the distribution of proper-time intervals between the two B decays, we obtain the following CP violation parameters: sin2 $\phi$ 1 =0.667±0.023(stat)±0.012(syst) and $A$ f =0.006±0.016(stat)±0.012(syst).

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Measurement of time-dependent CP violation in B 0 → η'K 0 decays

We present a measurement of the time-dependent CP violation parameters in B 0 → η'K 0 decays. The measurement is based on the full data sample containing 772×10 6 BB-bar pairs collected at the Υ(4S) resonance using the Belle detector at the KEKB asymmetric-energy e + e - collider. The measured values of the mixing-induced and direct CP violation parameters are: sin 2φ 1 eff = +0.68 ± 0.07 ± 0.03, A η'K 0 = +0.03 ± 0.05 ± 0.04, where the first uncertainty is statistical and the second is systematic. The values obtained are the most accurate to date. Furthermore, these results are consistent with our previous measurements and with the world-average value of sin 2φ 1 measured in B 0 → J/ψK 0 decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Measurement of the CP-violating phase β s J/ψΦ in B s 0 →J/ψΦ decays with the CDF II detector

We present a measurement of the CP-violating parameter β s J/ψΦ using approximately 6500 B 0 s →J/ψΦ decays reconstructed with the CDF II detector in a sample of pp̄ collisions at √s=1.96 TeV corresponding to 5.2 fb⁻¹ integrated luminosity produced by the Tevatron collider at Fermilab. We find the CP-violating phase to be within the range β s J/ψΦ ϵ [0.02,0.52]∪[1.08,1.55] at 68% confidence level where the coverage property of the quoted interval is guaranteed using a frequentist statistical analysis. This result is in agreement with the standard model expectation at the level of about one Gaussian standard deviation. We consider the inclusion of a potential S-wave contribution to the B 0 s →J/ψK⁺K⁻ final state which is found to be negligible over the mass interval 1.009 s J/ψΦ , we find the B 0 s decay width difference to be ΔΓ s =0.075±0.035(stat)±0.006(syst) ps⁻¹. We also present the most precise measurements of the B 0 s mean lifetime τ (B 0 s )=1.529±0.025(stat)±0.012(syst) ps, the polarization fractions |A0(0)|²=0.524±0.013(stat)±0.015(syst) and |A II (0)|²=0.231±0.014(stat)±0.015(syst), as well as the strong phase δ ⊥ =2.95±0.64(stat)±0.07(syst) rad. In addition, we report an alternative Bayesian analysis that gives results consistent with the frequentist approach.

Aaltonen, T.↗
DOE OSTI2012

Measurement of the CP-Violation Parameter sin2Φ 1 with a New Tagging Method at the Υ(5S) Resonance

We report a measurement of the CP-violation parameter sin2Φ 1 at the Υ(5S) resonance using a new tagging method, called “B-π tagging.” In Υ(5S) decays containing a neutral B meson, a charged B, and a charged pion, the neutral B is reconstructed in the J/ψK$0\atop{S}$ CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the Υ(5S) decay is opposite to that of the charged B and may thus be inferred from the charge of the pion without reconstructing the charged B. From the asymmetry between B - π + and B - π - tagged J/ψK$0\atop{S}$ yields, we determine sin2Φ 1 =0.57±0.58(stat)±0.06(syst). The results are based on 121 fb -1 of data recorded by the Belle detector at the KEKB e + e - collider.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Measuring $CP$ violation in $h$ → $τ$ + $τ$ – at colliders

We investigate the LHC and Higgs Factory prospects for measuring the CP phase in the Higgs-tau-tau coupling. Currently this phase can be anywhere between 0° (CP even) and 90° (CP odd). A new, ideal observable is identified from an analytic calculation for the τ ± → ρ ± ν → π ± π 0 ν channel. It is demonstrated to have promising sensitivity at the LHC and superior sensitivity at the ILC compared to previous proposals. Furthermore, our observable requires the reconstruction of the internal substructure of decaying taus but does not rely on measuring the impact parameter of tau decays. It is the first proposal for such a measurement at the LHC. For the 14 TeV LHC, we estimate that about 1 ab –1 data can discriminate CP-even versus CP-odd at the 5σ level. With 3 ab –1 , the CP phase should be measurable to an accuracy of ~11°. At an e + e – Higgs Factory, we project that a 250 GeV run with 1 ab –1 luminosity can measure the phase to ~4.4° accuracy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurement of the direct C P -violating parameter A C P in the decay D + → K - π + π +

We measure the direct C P -violating parameter A C P for the decay of the charged charm meson, D + → K - π + π + (and charge conjugate), using the full 10.4 fb - 1 sample of p p ¯ collisions at s = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from B → D processes) using input from Monte Carlo simulation. We measure A C P = [ - 0.16 ± 0.15 ( stat ) ± 0.09 ( syst ) ] % , which is consistent with zero, as expected from the standard model prediction of C P conservation, and is the most precise measurement of this quantity to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Observation of the decay $Λ^0_b$ → $pK$ - $μ$ + $μ$ - and a search for $CP$ violation

A search for $CP$ violation in the decay $Λ^0_b$ → $pK$ - $μ$ + $μ$ - is presented. This decay is mediated by flavour-changing neutral-current transitions in the Standard Model and is potentially sensitive to new sources of CP violation. The study is based on a data sample of proton-proton collisions recorded with the LHCb experiment, corresponding to an integrated luminosity of 3 fb -1 . The $Λ^0_b$ → $pK$ - $μ$ + $μ$ - decay is observed for the first time, and two observables that are sensitive to different manifestations of $CP$ violation are measured, $ΔΑ$ CP $\equiv$ $ΔΑ$ CP ($Λ^0_b$ → $pK$ - $μ$ + $μ$ - ) - $ΔΑ$ CP ($Λ^0_b$ → $pK$ - $J/Ψ$) and a C P T &#x005E;<!-- ^ --> - o d d , where the latter is based on asymmetries in the angle between the $μ$ + $μ$ - and $pK$ - decay planes. These are measured to be &#x0394;<!-- Δ --> A C P = ( &#x2212;<!-- - --> 3.5 &#x00B1;<!-- ± --> 5.0 ( s t a t ) &#x00B1;<!-- ± --> 0.2 ( s y s t ) ) &#x00D7;<!-- × --> 10 &#x2212;<!-- - --> 2 , a C P T &#x005E;<!-- ^ --> - o d d = ( 1.2 &#x00B1;<!-- ± --> 5.0 ( s t a t ) &#x00B1;<!-- ± --> 0.7 ( s y s t ) ) &#x00D7;<!-- × --> 10 &#x2212;<!-- - --> 2 , and no evidence for $CP$ violation is found

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

The impact of different parameterizations on the interpretation of CP violation in neutrino oscillations

CP violation in the lepton mass matrix will be probed with good precision in upcoming experiments. The amount of CP violation present in oscillations can be quantified in numerous ways and is typically parameterized by the complex phase δ PDG in the standard PDG definition of the lepton mixing matrix. There are additional parameterizations of the lepton mixing matrix as well. Through various examples, we explore how, given the current data, different parameterizations can lead to different conclusions when working with parameterization dependent variables, such as δ. We demonstrate how the smallness of |U e3 | governs the scale of these results. We then demonstrate how δ can be misleading and argue that the Jarlskog is the cleanest means of presenting the amount of CP violation in the lepton sector. We also confirm that, among the different parameterizations considered, the standard PDG parameterization has a number of convenient features.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

First Observation of C P Violation in B ¯ 0 → D C P ( * ) h 0 Decays by a Combined Time-Dependent Analysis of BABAR and Belle Data

We report a measurement of the time-dependent CP asymmetry of B¯ 0 → D$^{(*)}_{CP}$h 0 decays, where the light neutral hadron h 0 is a π 0 , η, or ω meson, and the neutral D meson is reconstructed in the CP eigenstates K + K – , K$^{0}_{S}$π 0 , or K$^{0}_{S}$ω. The measurement is performed combining the final data samples collected at the Υ(4S) resonance by the BABAR and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471 ± 3) × 10 6 BB¯ pairs recorded by the BABAR detector and (772 ± 11) × 10 6 BB¯ pairs recorded by the Belle detector. We measure the CP asymmetry parameters –ηfS = +0.66 ± 0.10(stat) ± 0.06(syst) and C = –0.02 ± 0.07(stat) ± 0.03(syst). Here, these results correspond to the first observation of CP violation in B¯ 0 → D$^{(*)}_{CP}$h 0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗