Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CP VIOLATION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Leptonic sum rules from flavour models with modular symmetries

Sum rules in the lepton sector provide an extremely valuable tool to classify flavour models in terms of relations between neutrino masses and mixing parameters testable in a plethora of experiments. In this manuscript we identify new leptonic sum rules arising in models with modular symmetries with residual symmetries. These models simultaneously present neutrino mass sum rules, involving masses and Majorana phases, and mixing sum rules, connecting the mixing angles and the Dirac CP-violating phase. The simultaneous appearance of both types of sum rules leads to some non-trivial interplay, for instance, the allowed absolute neutrino mass scale exhibits a dependence on the Dirac CP-violating phase. We derive analytical expressions for these novel sum rules and present their allowed parameter ranges as well as their predictions at upcoming neutrino experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Baryogenesis via particle-antiparticle oscillations

CP violation, which is crucial for producing the baryon asymmetry of the Universe, is enhanced in particle-antiparticle oscillations. We study particle-antiparticle oscillations [of a particle with mass O(100GeV)] with CP violation in the early Universe in the presence of interactions with O(ab-fb) cross sections. We show that if baryon-number-violating interactions exist, a baryon asymmetry can be produced via out-of-equilibrium decays of oscillating particles. As a concrete example we study a U(1)R-symmetric, R-parity-violating supersymmetry model with pseudo-Dirac gauginos, which undergo particle-antiparticle oscillations. Hence, taking bino to be the lightest U(1) R -symmetric particle, and assuming it decays via baryon-number-violating interactions, we show that bino-antibino oscillations can produce the baryon asymmetry of the Universe.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Standard Model Prediction for Direct C P Violation in K → π π Decay

In this paper, we report the first lattice QCD calculation of the complex kaon decay amplitude A 0 with physical kinematics, using a 32 3 x 64 lattice volume and a single lattice spacing a, with 1/a = 1.3784(68) GeV. We find Re(A 0 ) = 4.66(1.00)(1.26) x 10 -7 GeV and Im(A 0 ) = -1.90(1.23)(1.08) x 10 -11 GeV, where the first error is statistical and the second systematic. The first value is in approximate agreement with the experimental result: Re(A 0 ) = 3.3201(18) x 10 -7 GeV, while the second can be used to compute the direct CP-violating ratio Re(ϵ'/ϵ) = 1.38(5.15)(4.59) x 10 -4 , which is 2.1σ below the experimental value 16.6(2.3) x 10 -4 . Finally, the real part of A 0 is CP conserving and serves as a test of our method while the result for Re(ϵ'/ϵ) provides a new test of the standard model theory of CP violation, one which can be made more accurate with increasing computer capability.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

e + e – → ZH process in the SMEFT beyond leading order

We systematically study potential effects of Beyond the Standard Model physics in the e + e – → ZH process. To this end, we include all relevant dimension-6 Standard Model Effective Field Theory operators and work to next-to-leading order (NLO) accuracy in the electroweak coupling. We consider both polarized and unpolarized electron and positron beams and present results for $\sqrt {s}$ = 240, 365 and 500 GeV, emphasizing contributions where the NLO predictions differ significantly from the leading order results. At NLO, a sensitivity arises to operators that do not contribute at tree level, such as the Higgs tri-linear coupling, CP-violating operators, and dimension-6 operators involving the top quark, among many others. We compare the prospects of future e + e – colliders to explore these new physics effects with existing measurements from the LHC, electron EDMs (for CP violating operators), and Z pole measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of the branching fraction and C P asymmetry in B 0 → π 0 π 0 decays, and an improved constraint on φ 2

Here, we measure the branching fraction and C P violation asymmetry in the decay B 0 → π 0 π 0 , using a data sample of 752 × 10 6 B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB e + e - collider. The obtained branching fraction and direct C P asymmetry are B ( B → π 0 π 0 ) = [ 1.31 ± 0.19 ( stat ) ± 0.19 ( syst ) ] × 10 - 6 and A C P = + 0.14 ± 0.36 ( stat ) ± 0.10 ( syst ) , respectively. The signal significance, including the systematic uncertainty, is 6.4 standard deviations. Furthemore, we combine these results with Belle’s earlier measurements of B 0 → π + π - and B ± → π ± π 0 to exclude the C P -violating parameter φ 2 from the range 15.5 ° < φ 2 < 75.0 ° at 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Updated determination of D 0 – D ¯ 0 mixing and C P violation parameters with D 0 → K + π – decays

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of D 0 →K + π – to D 0 →K – π + rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of 5.0 fb –1 recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity ( CP ) symmetry, the mixing parameters are determined to be x' 2 =(3.9±2.7)×10 –5 , y'=(5.28±0.52)×10 –3 , and R D =(3.454±0.031)×10 –3 . Without this assumption, the measurement is performed separately for D 0 and D¯ 0 mesons, yielding a direct CP-violating asymmetry A D =(–0.1±9.1)×10 –3 , and magnitude of the ratio of mixing parameters 1.00 < |q/p| < 1.35 at the 68.3% confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of the C P Violation Parameter A Γ in D 0 → K + K - and D 0 → π + π - Decays

Asymmetries in the time-dependent rates of D 0 →K + K - and D 0 →$π$ + $π$ - decays are measured in a $pp$ collision data sample collected with the LHCb detector during LHC Run 1, corresponding to an integrated luminosity of 3 fb -1 . The asymmetries in effective decay widths between $D$ 0 and $\bar{D}$ 0 decays, sensitive to indirect $CP$ violation, are measured to be A $Γ$ (K + K - ) = (-0.30 ± 0.32 ± 0.10) × 10 -3 and A $Γ$ ($π$ + $π$ - ) = (0.46 ± 0.58 ± 0.12) × 10 -3 , where the first uncertainty is statistical and the second systematic. These measurements show no evidence for $CP$ violation and improve on the precision of the previous best measurements by nearly a factor of two.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Baryogenesis from oscillations of charmed or beautiful baryons

Here, we propose a model for CP violating oscillations of neutral, heavy-flavored baryons into antibaryons at rates which are within a few orders of magnitude of their lifetimes. The flavor structure of the baryon violation suppresses neutron oscillations and baryon number violating nuclear decays to experimentally allowed rates. We also propose a scenario for producing such baryons in the early Universe via the out-of-equilibrium decays of a neutral particle, after hadronization but before nucleosynthesis. We find parameters where CP violating baryon oscillations at a temperature of a few MeV could result in the observed asymmetry between baryons and antibaryons. Additionally, part of the relevant parameter space for baryogenesis is potentially testable at Belle II via decays of heavy flavor baryons into an exotic neutral fermion. The model introduces four new particles: three light Majorana fermions and a colored scalar. The lightest of these fermions is typically long lived on collider timescales and may be produced in decays of bottom and possibly charmed hadrons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Scalable qubit representations of neutrino mixing matrices

Oscillating neutrino beams exhibit quantum coherence over distances of thousands of kilometers. Their unambiguously quantum nature suggests an appealing test system for direct quantum simulation. Such techniques may enable presently analytically intractable calculations involving multi-neutrino entanglements, such as collective neutrino oscillations in supernovae, but only once oscillation phenomenology is properly re-expressed in the language of quantum circuits. Here we resolve outstanding conceptual issues regarding encoding of arbitrarily mixed neutrino flavor states in the Hilbert space of an n-qubit quantum computer. We introduce algorithms to encode mixing and oscillation of any number of flavor-mixed neutrinos, both with and without CP-violation, with an efficient number of prescriptive input parameters in terms of sub-rotations of the PMNS matrix in standard form. As a result, examples encoded for an IBM-Q quantum computer are shown to converge to analytic predictions both with and without CP-violation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Constraints on the unitarity triangle angle γ from Dalitz plot analysis of B 0 → D K + π – decays

The first study is presented of CP violation with an amplitude analysis of the Dalitz plot of B 0 → DK + π – decays, with D → K + π – , K + K – , and π + π – . The analysis is based on a data sample corresponding to 3.0 fb –1 of pp collisions collected with the LHCb detector. No significant CP violation effect is seen, and constraints are placed on the angle γ of the unitarity triangle formed from elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Hadronic parameters associated with the B 0 → DK *(892) 0 decay are determined for the first time. These measurements can be used to improve the sensitivity to γ of existing and future studies of the B 0 → DK *(892) 0 decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Paving the Way for Electroweak Baryogenesis

A detail look at the ingredients needed for creating the observed matter anomaly of the universe at the electroweak scale: new particles related to the Higgs boson, new sources of CP violation, and possibly new forces, all manifesting during the electroweak phase transition in the early universe. I will discuss three examples of plausible scenarios, two focused on the problem of preserving an asymmetry once created, and the third exhibiting a new mechanism where the source of both CP violation and the resulting asymmetry comes from the dark matter sector.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Interpreting the electron EDM constraint

The ACME collaboration has recently announced a new constraint on the electron EDM, |d e | < 1.1 × 10 -29 e cm, from measurements of the ThO molecule. This is a powerful constraint on CP-violating new physics: even new physics generating the EDM at two loops is constrained at the multi-TeV scale. We interpret the bound in the context of different scenarios for new physics: a general order-of-magnitude analysis for both the electron EDM and the CP-odd electron-nucleon coupling; 1-loop SUSY, probing sleptons above 10 TeV; 2-loop SUSY, probing multi-TeV charginos or stops; and finally, new physics that generates the EDM via the charm quark or top quark Yukawa couplings. In the last scenario, new physics generates a “QULE operator” ($q_{ƒ}\overline{σ}^{μν}\overline{u}_{ƒ}$)&middot;($ℓ\overline{σ}_{μν}\overline{e}$), which in turn generates the EDM through RG evolution. If the QULE operator is generated at tree level, this corresponds to a previously studied leptoquark model. For the first time, we also classify scenarios in which the QULE operator is generated at one loop through a box diagram, which include (among others) SUSY and leptoquark models. The electron EDM bound is the leading constraint on a wide variety of theories of CP-violating new physics interacting with the Higgs boson or the top quark. We argue that any future nonzero measurement of an electron EDM will provide a strong motivation for constructing new colliders at the highest feasible energies.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Study of B 0 → ρ + ρ – decays and implications for the CKM angle Φ 2

We present a measurement of the branching fraction and the longitudinal polarization fraction of B 0 → ρ + ρ – decays, as well as the time-dependent CP violating parameters in decays into longitudinally polarized ρ + ρ – pairs with Belle’s final data set of 772 × 10 6 BB¯ pairs, at the Υ(4S) resonance, collected at the asymmetric-energy e + e – collider KEKB. We obtain B(B 0 → ρ + ρ – ) = (28.3 ± 1.5(stat) ± 1.5(syst)) × 10 –6 , f L = 0.988 ± 0.012(stat) ± 0.023(syst), A CP = 0.00 ± 0.10(stat) ± 0.06(syst), S CP = –0.13 ± 0.15(stat) ± 0.05(syst). As a result, we perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle Φ 2 and obtain two solutions with Φ 2 = (93.7 ± 10.6)°, being most compatible with other Standard-Model based fits to the data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Accelerator-Based Neutrino Beams

Over the past six decades, accelerator-based neutrino beams have revolutionized particle physics. Neutrinos created with accelerators have been used to discover the muon neutrino and tau neutrinos was discovered and to confirm the existence of neutrino oscillations. More recently, long-baseline experiments have offered the first experimental hint of CP violation in the neutrino sector. Building and operating such beams is an enormous technical challenge, yet they remain our most versatile tool for studying neutrinos. With new experiments such as DUNE and Hyper-Kamiokande, and ideas such as neutrino factories, the next generation of beams will address open questions about neutrino mass ordering, CP violation, and possible physics beyond the standard model.

Fields, Laura [Notre Dame U.] (ORCID:0000000182813↗
DOE OSTI2021

Electroweak-like baryogenesis with new chiral matter

We propose a framework where a phase transition associated with a gauge symmetry breaking that occurs (not far) above the electroweak scale sets a stage for baryogenesis similar to the electroweak baryogenesis in the Standard Model. A concrete realization utilizes the breaking of SU(2) R × U(1) X → U(1) Y . New chiral fermions charged under the extended gauge symmetry have nonzero lepton numbers, which makes the B - L symmetry anomalous. The new lepton sector contains a large flavor-dependent CP violation, similar to the Cabibbo-Kobayashi-Maskawa phase, without inducing sizable electric dipole moments of the Standard Model particles. A bubble wall dynamics associated with the first-order phase transition and SU(2) R sphaleron processes generate a lepton asymmetry, which is transferred into a baryon asymmetry via the ordinary electroweak sphaleron process. Unlike the Standard Model electroweak baryogenesis, the new phase transition can be of the strong first order and the new CP violation is not significantly suppressed by Yukawa couplings, so that the observed asymmetry can be produced. The model can be probed by collider searches for new particles and the observation of gravitational waves. One of the new leptons becomes a dark matter candidate. The model can be also embedded into a left-right symmetric theory to solve the strong CP problem.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Constraints on neutrino oscillation parameters with the NOvA experiment

NOvA is a long-baseline neutrino oscillation experiment, which consists of two finely-segmented liquid-scintillator detectorsoperating 14 mrad off-axis from the NuMI muon neutrino beam. With an 810 km baseline, the combined measurements of muon neutrino disappearance and electron neutrino appearance allow the determination of neutrino oscillation unknowns, namely the mass hierarchy, the octant of the largest neutrino mixing angle, and the CP violating phase.In this dissertation, I present the joint analysis of $\nu_\mu\to\nu_\mu$ and $\nu_mu\to\nu_e$ oscillation data with an exposure of$8.85\times10^{20}$ protons on target on the 14 kton detector. It includes the estimation of neutrino energy distributions in the fardetector using near detector data constraints, details of the implementation of the simultaneous fit of \numu and \nue samples, andthe effect of systematic uncertainties on the measurement of oscillation parameters. I also discuss NOvA's projected sensitivity to determine the mass hierarchy and discover CP violation in future analyses with increased exposure and the addition ofantineutrino datasets.With 66 electron neutrino and 126 muon neutrino candidates, the bestfit to the data corresponds to the normal mass hierarchy, $\Delta m^2_{32}=2.44\times 10^{-3} eV^2/c^4$, $\sin^2\theta_{23}=0.56$,and $\delta_{CP} = 1.21\pi$, with the allowed regions $\Delta m^2_{32} \in[2.37,2.52]\times 10^{-3} eV^2/c^4$, $\sin^2\theta_{23} \in [0.43,0.51] \cup[0.52,0.60]$ and $\delta_{CP} \in [0,0.12\pi] \cup [0.91\pi,2\pi]$ at the68.3\% C.L. Our data disfavor maximal mixing by 0.8$\sigma$, $\delta_{CP}= \pi/2$ in the inverted hierarchy at higher than 3$\sigma$, and theentire inverted mass hierarchy at the 95\% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Proton Scattering in NOvA Test Beam

The NuMI Off-axis $\nu_e$ Appearance (NOvA) experiment is a two-detector, long baseline, neutrino oscillation experiment, which aims to make a determination of the neutrino mass ordering, the octant of $\theta_{23}$, and measure possible charge-parity (CP) violation. Determining these parameters is a step towards answering some of the fundamental questions about neutrinos. Are neutrinos their own antiparticle? Could neutrinos be responsible for the matter-antimatter asymmetry of the universe? How do neutrinos get their mass? Answering these questions requires precise measurements of the parameters that govern how neutrinos behave, namely the mass squared splittings, mixing angles, and possible CP-violating phase factor in the PNMS matrix. Reaching high precision requires minimizing both statistical and systematic errors. As NOvA continues to accumulate data, the sizes of our statistical errors continue to shrink such that in a couple of years they will be comparable to our systematic errors. NOvA's current systematic errors are dominated by energy and calibration uncertainties. The Test Beam program was initiated to address these uncertainties by assessing the detector response in an environment where more parameters of the incoming particles are known. One of the main goals of the Test Beam program is to garner a better understanding of our systematic errors, particularly in energy measurement and detector response, so that the modeling of these parameters can be improved. I studied protons in the Test Beam Detector with momenta around \unit[1]{GeV/c}, the high end of the momentum range relevant to quasielastic neutrino interactions in NOvA. One question this sample can help to answer is if we correctly simulate the fraction of protons that have an inelastic scattering interaction versus ranging out. If protons inelastically scatter at different rates in our simulation and data, the correction applied to the hadronic system when reconstructing neutrino energy could be inaccurate, since events with inelastic scattering will have less visible energy in the detector. This is particularly important for quasielastic $\nu_\mu$ events, which have the lowest hadronic energy resolution, and therefore give us our best measurements of $\Delta m_{32}^2$ and $\theta_{23}$.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗