Direct CP violation in neutral kaon decays

The final result is presented of the NA48 Experiment performed at CERN SPS neutral kaon beams on the direct CP violation parameter Re(epsilon'/epsilon), as maesured from the decay rates of neutral kaons into two pions. The data collected in years 1997-2001 yield the evidence for direct CP violation with Re(epsilon'/epsilon)=(14.7+-2.2)10^-4. Description of expermental method and systematics, comparison with world data and some discussion of implications for theory are given.Comment: 5 pp., 3 figs, presented on behalf of NA48 Collaboration at PASCOS 2003 Conference, Mumbai, India, 2-8 Jan 2003, to appear in Praman

Developments in Rare Kaon Decay Physics

We review the current status of the field of rare kaon decays. The study of rare kaon decays has played a key role in the development of the standard model, and the field continues to have significant impact. The two areas of greatest import are the search for physics beyond the standard model and the determination of fundamental standard-model parameters. Due to the exquisite sensitivity of rare kaon decay experiments, searches for new physics can probe very high mass scales. Studies of the k->pnn modes in particular, where the first event has recently been seen, will permit tests of the standard-model picture of quark mixing and CP violation.Comment: One major revision to the text is the branching ratio of KL->ppg, based on a new result from KTeV. Several references were updated, with minor modifications to the text. A total of 48 pages, with 28 figures, in LaTeX; to be published in the Annual Review of Nuclear and Particle Science, Vol. 50, December 200

Exploring The Impact of Discussion Interfaces on Diversified Interconnectivity in Online Learning Communities

Asynchronous online discussions are widely recognized as potent pedagogical practices for actively involving learners in the process of constructing knowledge and cultivating a thriving learning community. This study examined how the types of online discussion threads (i.e., student-based vs. topic-based) moderate diverse of social interconnection in discussions and how it changes over time. An upward trajectory in the diversification of interconnectivity was discerned. In spite of the shift from student-based to topic-based, students continue valuing the power of diversified interconnecting with their classmates. The significant drop, but transitory, from Week 3 to 4 can be explained by the switch to another discussion type. Both the student-based and topic-based threads were observed to facilitate comparable levels of diverse connectivity. However, they accentuated subtle attributes within the learning communities. Instead of deciding upon any asynchronous online discussion tools given by institution’s LMS, instructors should critically assess different discussion thread interfaces and integrate a relevant one to create and facilitate their ideal and effective, yet diverse learning community. Future research should explore diverse interconnectivity traits and extend the timeframe beyond three weeks to observe the enduring impacts on learning community development

Radiative Corrections to Double Dalitz Decays: Effects on Invariant Mass Distributions and Angular Correlations

We review the theory of meson decays to two lepton pairs, including the cases of identical as well as non-identical leptons, as well as CP-conserving and CP-violating couplings. A complete lowest-order calculation of QED radiative corrections to these decays is discussed, and comparisons of predicted rates and kinematic distributions between tree-level and one-loop-corrected calculations are presented for both pi-zero and K-zero decays.Comment: 25 pages, 18 figures, added figures and commentar

Light hadron spectrum and quark masses in QCD with two flavors of dynamical quarks

We present updated results of the CP-PACS calculation of the light hadron spectrum in $N_{\rm f}=2$ full QCD. Simulations are made with an RG-improved gauge action and a tadpole-improved clover quark action for sea quark masses corresponding to $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.6 and the lattice spacing $a=0.22$--0.09 fm. A comparison of the full QCD spectrum with new quenched results, obtained with the same improved action, shows clearly the existence of sea quark effects in vector meson masses. Results for light quark masses in $N_{\rm f}=2$ QCD are also presented.Comment: Latex 3 pages, 6 PostScript figures, Talk presented at LATTICE99(QCD Spectrum and Quark Masses

Direct CP, T and/or CPT violations in the K^0-\bar{K^0} system - Implications of the recent KTeV results on 2π2\pi decays -

The recent results on the CP violating parameters Re(e'/e) and \Delta\phi = \phi_{00}-\phi_{+-} reported by the KTeV Collaboration are analyzed with a view to constrain CP, T and CPT violations in a decay process. Combining with some relevant data compiled by the Particle Data Group, we find Re(e_2-e_0) = (0.85 +- 3.11)*10^{-4} and Im(e_2-e_0) = (3.2 +- 0.7)*10^{-4}, where Re(e_I) and Im(e_I) represent respectively CP/CPT and CP/T violations in decay of K^0 and \bar{K^0} into a 2\pi state with isospin I.Comment: 7 pages, No figure

Experimental search for the decay mode K_L -> pi^0 gamma e^+ e^-

We report on results of a search for the decay mode K_L -> pi^0 gamma e^+ e^- conducted by the E162 experiment at KEK. We observed no events and set a 90% confidence level upper limit of Br(K_L -> pi^0 gamma e^+ e^-)< 7.1x10^{-7} for its branching ratio. This is the first published experimental result on this decay mode.Comment: 10 pages, 4 figures, submitted to Physics Letters

Rare Kaon Decays

The current status of rare kaon decay experiments is reviewed. New limits in the search for Lepton Flavor Violation are discussed, as are new measurements of the CKM matrix.Comment: 8 pages, 3 figures, LaTeX, presented at the 3rd International Conference on B Phyiscs and CP Violation, Taipei December 3-7, 199

Can the polarization of the strange quarks in the proton be positive ?

Recently, the HERMES Collaboration at DESY, using a leading order QCD analysis of their data on semi-inclusive deep inelastic production of charged hadrons, reported a marginally positive polarization for the strange quarks in the proton. We argue that a non-negative polarization is almost impossible.Comment: 6 pages, latex, minor changes in the discussion after Eq. (9

Comparative effectiveness of alternative intervals between first and second doses of the mRNA COVID-19 vaccines

The optimal interval between the first and second doses of COVID-19 mRNA vaccines has not been thoroughly evaluated. Employing a target trial emulation approach, we compared the effectiveness of different interdose intervals among >6 million mRNA vaccine recipients in Georgia, USA, from December 2020 to March 2022. We compared three protocols defined by interdose interval: recommended by the Food and Drug Administration (FDA) (17-25 days for Pfizer-BioNTech; 24-32 days for Moderna), late-but-allowable (26-42 days for Pfizer-BioNTech; 33-49 days for Moderna), and late ( ≥ 43 days for Pfizer-BioNTech; ≥50 days for Moderna). In the short-term, the risk of SARS-CoV-2 infection was lowest under the FDA-recommended protocol. Longer-term, the late-but-allowable protocol resulted in the lowest risk (risk ratio on Day 120 after the first dose administration compared to the FDA-recommended protocol: 0.83 [95% confidence interval: 0.82-0.84]). Here, we showed that delaying the second dose by 1-2 weeks may provide stronger long-term protection