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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2010

Final state interactions and CP violation in B decays to three pseudoscalars

We study CP violation and final state interactions between pions and kaons in B{sup +}, B{sup -}, -B{sup 0} and B-bar{sup 0} decays into K{pi}{pi}. The weak transition amplitudes consist of two terms: the first part is derived in QCD factorization approach and the second one is a phenomenological long-distance charming penguin contribution. The final state K{pi} interactions in S- and P-waves are described by strange scalar and vector form factors, respectively. These are determined using a unitary coupled channel model together with chiral symmetry and asymptotic QCD constraints. The final state interactions are dominated by presence of the scalar K{sub 0}*(1430) and the vector K*(892) resonances. We show that additional charming penguin amplitudes are needed to reproduce the latest experimental K{pi} effective mass and helicity angle distributions, branching fractions and asymmetries obtained by Belle and BaBar collaborations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

D0 Evidence for CP Violation and Implication for CPT Violation in B-Meson Mixing

A D0 analysis measuring the charge asymmetry A{sub sl}{sup b} 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 B{sub s}{sup 0} {yields} J/{psi}{phi}. If CPT violation is allowed, the dimuon asymmetry also yields the first sensitivity to CPT violation in the B{sub s}{sup 0} system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

CP-violating phases in M theory and implications for electric dipole moments

We demonstrate that in effective theories arising from a class of N=1 fluxless compactifications of M theory on a G{sub 2} manifold with low-energy supersymmetry, CP-violating phases do not appear in the soft-breaking Lagrangian except via the Yukawas appearing in the trilinear parameters. Such a mechanism may be present in other string compactifications as well; we describe properties sufficient for this to occur. CP violation is generated via the Yukawas since the soft trilinear matrices are generically not proportional to the Yukawa matrices. Within the framework considered, the estimated theoretical upper bounds for electric dipole moments of the electron, the neutron, and mercury are all within the current experimental limits and could be probed in the near future.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

CKM-UT Angles: Mixing And CP Violation at the B Factories

We review the experimental status of the angles of the Unitarity Triangle of the CKM matrix, as measured by the BABAR and Belle experiments. The B Factories have demonstrated since the beginning of this decade that CP violation in the B meson system is consistent with the Standard Model (SM) description in terms of the complex phase in the three-by-three Cabibbo-Kobayashi-Maskawa (CKM) matrix. With one single phase, the SM predicts clear patterns for quark mixing and CP violations, to be satisfied by all processes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Leading effect of CP violation with four generations

In the standard model with a fourth generation of quarks, we study the relation between the Jarlskog invariants and the triangle areas in the 4x4 Cabibbo-Kobayashi-Maskawa matrix. To identify the leading effects that may probe the CP violation in processes involving quarks, we invoke small mass and small angle expansions, and show that these leading effects are enhanced considerably compared to the three-generation case by the large masses of fourth-generation quarks. We discuss the leading effect in several cases, in particular, the possibility of large CP violation in b{yields}s processes, which echoes the heightened recent interest because of experimental hints.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Allowance for CP violation in the exponential parametrization of neutrino mixing

An exponential form of the Pontecorvo–Maki–Nakagawa–Sakatamixingmatrix for neutrinos is discussed. This form makes it possible to separate the contributions of purely rotational components of the mixing matrix and elements that are responsible for CP violation. The logarithm of the mixing matrix and exact values for each parameter of the exponential neutrino mixing matrix are found on the basis of the most recent experimental data on neutrino mixing. The parameters of the real rotational part in the exponential representation of the mixing matrix and the parameters of its imaginary part, which is responsible for CP violation, are evaluated. The hypothesis of complementarity of quark and neutrino mixing is confirmed. Factorization in the form of the product of rotations about the real and imaginary axes is demonstrated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Leveraging intermediate resonances to probe CP violation at colliders

We explore the phenomenological impact of interference in tree-level contributions to three-body final states in $2\rightarrow 3$ scattering processes. This work introduces a novel search strategy leveraging asymmetries to enable sensitivity to CP-violating effects in less well-explored regions of phase space. Analytically, we demonstrate the effectiveness of this observable in probing interference between Standard Model charged-current decays and effective left-handed vector interactions, illustrated in a toy model featuring a scalar leptoquark, $S_1 \sim (3, 1, -\,1/3)$. Numerically, we apply this framework to studying the process $pp\rightarrow b \tau \nu $; unlike traditional high-$p_T$ searches or “bump hunts”, this approach utilizes an intermediate energy regime – where new physics is neither light enough to be produced on shell or heavy enough to justify an effective field theory treatment. A proof-of-principle analysis at parton level demonstrates a percent-level asymmetry, with sensitivity also to BSM weak-CP phase. While the specific phase sensitivity is diminished at particle level due to showering and detector effects, a machine learning classifier can recover sensitively to the presence of SM-BSM interference, significantly outperforming standard analysis methods. Notably discrimination between BSM signal and SM background could be achieved at the 2$\sigma $ level for the current LHC dataset and 8$\sigma $ at the High-Luminosity LHC. Moreover, this asymmetry observable as defined can also be more broadly applied to other searches for CP-violation in $2\rightarrow 3$ processes in present and future collider environments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Charmed Baryon Spectroscopy and Search for $CP$ Violation in $D^0 \to K_S^0\,\pi^+\,\pi^-$ at CDF

In this thesis two different analyses are presented, namely the measurements of the properties of $\Lambda_c(2595)^+$, $\Lambda_c(2625)^+$, $\Sigma_c(2455)^{++,0}$, and $\Sigma_c(2520)^{++,0}$ baryons as well as the search for $CP$ violation in the Dalitz plot of the decay $D^0 \to K_S^0\,\pi^+\,\pi^-$. Both studies are performed using data corresponding to 5.2\,\invfb respective 6.0\,\invfb of integrated luminosity from $p\bar{p}$ collisions at a center-of-mass energy of 1.96\,TeV, collected with the CDF~II detector at the Fermilab Tevatron. The masses and decay widths of the mentioned charmed baryon resonances are measured with uncertainties comparable to the world averages for $\Sigma_c$ states, and significantly smaller uncertainties than the world averages for excited $\Lambda_c^+$ states. No hints for any $CP$ violating effects in the resonant substructure of $D^0 \to K_S^0\,\pi^+\,\pi^-$ are found.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

CP Violation and Mixing in Charm Meson Decays from BaBar

Mixing and CP violation in charm meson decays provide a unique probe of possible physics beyond the standard model. In this paper, we give a brief review of the current measurements from the BABAR experiment.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

First measurement of the CP-violating phase in $B_{s}^{0}$→J/ψ(→ e + e - )Φ decays

A flavour-tagged time-dependent angular analysis of $B_{s}^{0}$→J/ψΦ decays is presented where the J/ψ meson is reconstructed through its decay to an e + e - pair. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8\,Te V, corresponding to an integrated luminosity of 3\,fb -1 . The CP-violating phase and lifetime parameters of the $B_{s}^{0}$ system are measured to be Φ s =0.00±0.28±0.07\,rad , ΔΓ s =0.115±0.045±0.011\,ps -1 and Γ s =0.608±0.018±0.012\,ps -1 where the first uncertainty is statistical and the second systematic. This is the first time that CP-violating parameters are measured in the $B_{s}^{0}$→J/ψΦ decay with an e + e - pair in the final state. The results are consistent with previous measurements in other channels and with the Standard Model predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Testing the CP-violating MSSM in stau decays at the LHC and ILC

We study CP violation in the two-body decay of a scalar tau into a neutralino and a tau, which should be probed at the LHC and ILC. From the normal tau polarization, a CP asymmetry is defined which is sensitive to the CP phases of the trilinear scalar coupling parameter A{sub {tau}}, the gaugino mass parameter M{sub 1}, and the Higgsino mass parameter {mu}, in the stau-neutralino sector of the minimal supersymmetric standard model. Asymmetries of more than 70% are obtained in scenarios with strong stau mixing. As a result, detectable CP asymmetries in stau decays at the LHC are found, motivating further detailed experimental studies for probing the supersymmetry CP phases.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Constraints on light QCD and CP-violating axions from the death line of rotation-powered pulsars

For axions that couple to nucleons, the presence of dense nuclear matter can displace the axion from its vacuum minimum, sourcing large field gradients around neutron stars (and, more generally, compact objects). These gradients, which we refer to as axion hair, couple to the local background magnetic field, inducing a large voltage drop near the surface of the star; here, we demonstrate that the presence of axion hair decouples local near-field particle acceleration in the open magnetic field line bundle from the rotational frequency of the pulsar itself. This is significant as the non-observation of old slowly-rotating pulsars is attributed to the fact the rotationally-induced electric fields are not strong enough to sustain $e^\pm$ pair production. In this work, we review the evidence for the existence for `pulsar death', i.e. the threshold at which $e^\pm$ pair production (and thus, by association, coherent radio emission) ceases, and demonstrate using both semi-analytics and particle-in-cell simulations that the existence of axion hair can dramatically extend pulsar lifetimes. We show that the non-observation of extremely old, slowly rotating, pulsars allows for a new probe of light QCD and CP-violating axions. We also demonstrate how the observation of emission from both poles of pulsars with nearly orthogonal rotational and magnetic axes, as seen e.g. in PSR J1906+0746, can be used to set competitive limits on CP-violating axion-nucleon interactions.

Witte, Samuel J. [Oxford U., Theor. Phys.; DESY; H↗
DOE OSTI2013

CPsuperH2.3: an Updated Tool for Phenomenology in the MSSM with Explicit CP Violation

We describe the Fortran code CPsuperH2.3, which incorporates the following updates compared with its predecessor CPsuperH2.0. It implements improved calculations of the Higgs-boson masses and mixing including stau contributions and finite threshold effects on the tau-lepton Yukawa coupling. It incorporates the LEP limits on the processes e^+e^-->H_iZ,H_iH_j and the CMS limits on H_i->@t@?@t obtained from 4.6 fb^-^1 of data at a center-of-mass energy of 7 TeV. It also includes the decay mode H_i->Z@c and the Schiff-moment contributions to the electric dipole moments of Mercury and Radium 225, with several calculational options for the case of Mercury. These additions make CPsuperH2.3 a suitable tool for analyzing possible CP-violating effects in the MSSM in the era of the LHC and a new generation of EDM experiments. Program summary: Program title: CPsuperH2.3 Catalogue identifier: ADSR_v3_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSR_v3_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 24058 No. of bytes in distributed program, including test data, etc.: 158721 Distribution format: tar.gz Programming language: Fortran77. Computer: PC running under Linux and computers in Unix environment. Operating system: Linux. RAM: 32 MB Classification: 11.1. Does the new version supersede the previous version?: Yes Catalogue identifier of previous version: ADSR_v2_0 Journal reference of previous version: Comput. Phys. Comm. 180(2009)312 Nature of problem: The calculations of mass spectrum, decay widths and branching ratios of the neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model with explicit CP violation have been improved. The program is based on renormalization-group-improved diagrammatic calculations that include dominant higher-order logarithmic and threshold corrections, b-quark and @t-lepton Yukawa-coupling resummation effects and improved treatment of Higgs-boson pole-mass shifts. The couplings of the Higgs bosons to the Standard Model gauge bosons and fermions, to their supersymmetric partners and all the trilinear and quartic Higgs-boson self-couplings are also calculated. Also included are a full treatment of the 4x4 (2x2) neutral (charged) Higgs propagator matrix together with the center-of-mass dependent Higgs-boson couplings to gluons and photons, and an integrated treatment of several B-meson observables. The new implementations include the EDMs of Thallium, neutron, Mercury, Deuteron, Radium, and muon, as well as the anomalous magnetic moment of muon, (g_@m-2), the top-quark decays, improved calculations of the Higgs-boson masses and mixing including stau contributions, the LEP limits, and the CMS limits on H_i->@t@t@?. It also implements the decay mode H_i->Z@c and includes the corresponding Standard Model branching ratios of the three neutral Higgs bosons in the array GAMBRN(IM,IWB = 2,IH). Solution method: One-dimensional numerical integration for several Higgs-decay modes and EDMs, iterative treatment of the threshold corrections and Higgs-boson pole masses, and the numerical diagonalization of the neutralino mass matrix. Reasons for new version: Mainly to provide the full calculations of the EDMs of Thallium, neutron, Mercury, Deuteron, Radium, and muon as well as (g_@m-2), improved calculations of the Higgs-boson masses and mixing including stau contributions, the LEP limits, the CMS limits on H_i->@t@t@?, the top-quark decays, H_i->Z@c decay, and the corresponding Standard Model branching ratios of the three neutral Higgs bosons. Summary of revisions: Full calculations of the EDMs of Thallium, neutron, Mercury, Deuteron, Radium, and muon as well as (g_@m-2). Improved treatment of Higgs-boson masses and mixing including stau contributions. The LEP limits. The CMS limits on H_i->@t@t@?. The top-quark decays. The H_i->Z@c decay. The corresponding Standard Model branching ratios of the three neutral Higgs bosons. Running time: Less than 1.0 s.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Flavor and CP violation with fourth generations revisited

The standard model predicts a very small CP violation phase sin2{Phi}{sub B{sub s}{sup SM{approx_equal}}-0.04 in B{sub s}}-B{sub s} mixing. Any finite value of {Phi}{sub B{sub s}} measured at the Tevatron would imply new physics. With recent hints for finite sin2{Phi}{sub B{sub s}}, we reconsider the possibility of a fourth generation. As recent direct search bounds have become considerably heavier than 300 GeV, we take the t{sup '} mass to be near the unitarity bound of 500 GeV. Combining the measured values of {Delta}m{sub B{sub s}} with B(B{yields}X{sub s}l{sup +}l{sup -}), together with typical f{sub B{sub s}} values, we find a sizable sin2{Phi}{sub B{sub s}}{sup SM4}{approx}-0.33. Using m{sub b}{sup '}=480 GeV, we extract the range 0.06<|V{sub t}{sup '}{sub b}|<0.13 from the constraints of {Gamma}(Z{yields}bb), {Delta}m{sub D}, and B(K{sup +}{yields}{pi}{sup +}{nu}{nu}). This illustrates how the 4x4 mixing matrix can be determined in the future, once m{sub t}{sup '} and m{sub b}{sup '} are known. A crucial future measurement would be B(K{sub L{yields}{pi}}{sup 0{nu}{nu}}), which would determine V{sub t}{sup '}{sub d}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Measurement of branching fractions and search for CP violation in $D^0 → π^+π^-η, D^0 → K^+K^-η$, and $D^0 → Φη$ at Belle

We measure the branching fractions and CP asymmetries for the singly Cabibbo-suppressed decays $D^0 → π^+π^-η, D^0 → K^+K^-η$, and $D^0 → Φη$, using 980 fb -1 of data from the Belle experiment at the KEKB e + e - collider. We obtain $$\mathcal{B}(D^0 → π^+π^-η = \mathrm{[1.22 ± 0.02 (stat) ± 0.02(syst) ± 0.03}(\mathcal{B}_{\mathrm{ref}})] \mathrm{x 10^{-3}}$$ $$\mathcal{B}(D^0 → K^+K^-η = \mathrm{[1.80^{+0.07}_{-0.06}(stat) ± 0.04 (syst) ± 0.05}(\mathcal{B}_{\mathrm{ref}})] \mathrm{x 10^{-4}}$$ $$\mathcal{B}(D^0 → Φη = \mathrm{[1.84 ± 0.09 (stat) ± 0.0 (syst) ± 0.05}(\mathcal{B}_{\mathrm{ref}})] \mathrm{x 10^{-4}}$$ where the third uncertainty ($\mathcal{B}_{\mathrm{ref}}$) is from the uncertainty in the branching fraction of the reference mode $D^0 → K^-π^+η$. The color-suppressed decay $D^0 → Φη$ is observed for the first time, with very high significance. The results for the CP asymmetries are $$A_{CP} (D^0 → π^+π^-η) = \mathrm{[0.9 ± 1.2 (stat) ± 0.5 (syst)]}\%$$ $$A_{CP} (D^0 → K^+K^-η) = \mathrm{[-1.4 ± 3.3 (stat) ± 1.1 (syst)]}\%$$ $$A_{CP} (D^0 → Φη) = \mathrm{[-1.9 ± 4.4 (stat) ± 0.6 (syst)]}\%$$ The results for $D^0 → π^+π^-η$ are a significant improvement over previous results. The branching fraction and A CP results for $D^0 → K^+K^-η$, and the ACP result for $D^0 → Φη$, are the first such measurements. No evidence for CP violation is found in any of these decays.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Measurement of CP violation parameters and polarisation fractions in $ {\mathrm{B}}_{\mathrm{s}}^0\to \mathrm{J}/\psi {\overline{\mathrm{K}}}^{\ast 0}$ decays

The first measurement of CP asymmetries in the decay ${B}_s^0\to J/\psi {\overline{\mathrm{K}}}^{\ast }{(892)}^0$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of 3.0 fb -1 of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Together with constraints from B $^o$ → J/$ψ$ $ρ$ $^o$, the results are used to constrain additional contributions due to penguin diagrams in the CP -violating phase $\phi_s$, measured through $B_s$ $^o$ decays to charmonium.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Nuclear Schiff Moments and CP Violation

This article reviews the calculation of nuclear Schiff moments, which one must know in order to interpret experiments that search for time-reversal-violating electric dipole moments in certain atoms and molecules. After briefly reviewing the connection between dipole moments and CP violation in and beyond the Standard Model of particle physics; Schiff's theorem, which concerns the screening of nuclear electric dipole moments by electrons; Schiff moments; and experiments to measure dipole moments in atoms and molecules, this review examines attempts to compute Schiff moments in nuclei such as 199 Hg and octupole-deformed isotopes such as 225 Ra, which are particularly useful in experiments. It then turns to ab initio nuclear-structure theory, describing ways in which both the in-medium similarity renormalization group and coupled-cluster theory can be used to compute important Schiff moments more accurately than the less controlled methods that have been applied so far.

CP violation↗
DOE OSTI2012

Sources of CP violation from E{sub 6} inspired heterotic string model

Sources of the weak CP violation from the SU{sub L}(3)x SU{sub R}(3)x SU{sub c}(3) subgroup of the E{sub 6} inspired heterotic string model are discussed. It is shown that the number of the Cabibo-Kobayachi-Maskawa like matrices depends on the spontaneous breakdown of the E{sub 6} gauge symmetry and/or supersymmetry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗