Vestibulo-oculomotor Function Following a Competitive Season Versus a Non-competitive Season in Collegiate Football Players

Introduction Background Football athletes experience a high number of head impacts during competitive play that do not cause immediate observable signs or symptoms. Research shows that exposure to repeated subconcussive impacts has a negative effect on the vestibulo-oculomotor (V-O) system and can result in long term neurologic dysfunction. Little is known about the ability of the V-O system to recover if an athlete is given an extended time away from subconcussive impacts. Purpose To investigate the difference in V-O function following a non-competitive (due to COVID-19) vs. a competitive season in cleared-to-play football players. Methods Participants 32 Division II football players from Concordia University, St. Paul ages 19-23. Data was collected in 2021 following a non-competitive season and in 2022 following a competitive season. V-O Tests Dynamic Visual Acuity (DVA) Near-Point Convergence (NPC) Results No statistically significant differences in V-O test results were found between the non-competitive and competitive season. Nearly 60% of the athletes had at least one positive V-O test after the competitive season. Conclusion Time away from subconcussive impacts due to a non-competitive season does not appear to have significantly influenced V-O function in collegiate football players. However, of concern is the large number of cleared-to-play athletes testing positive in at least one assessment tool. Clinical Relevance The vestibular system has the opportunity to recover, yet we are still unable to draw firm conclusions about the amount of time away from head impacts that is necessary for full recovery For many of our participants, a single season away from head impacts was not enough time to recover It is recommended that there be further investigation into time away from contact sports and return-to-play protocols in season

First Observation of the decay KL -> pi0 e e gamma

We report on the first observation of the decay KL -> pi0 ee gamma by the KTeV E799 experiment at Fermilab. Based upon a sample of 48 events with an estimated background of 3.6 +/- 1.1 events, we measure the KL -> pi0 ee gamma branching ratio to be (2.34 +/- 0.35 +/- 0.13)x10^{-8}. Our data agree with recent O(p^6) calculations in chiral perturbation theory that include contributions from vector meson exchange through the parameter a_V. A fit was made to the KL -> pi0 ee gamma data for a_V with the result -0.67 +/- 0.21 +/- 0.12, which is consistent with previous results from KTeV.Comment: Submitted to Physical Review Letters, 5 pages, 5 figure

Search for Light Gluinos via the Spontaneous Appearance of pi+pi- Pairs with an 800 GeV/c Proton Beam at Fermilab

We searched for the appearance of pi+pi- pairs with invariant mass greater than 648 MeV in a neutral beam. Such an observation could signify the decay of a long-lived light neutral particle. We find no evidence for this decay. Our null result severely constrains the existence of an R0 hadron, which is the lightest bound state of a gluon and a light gluino, and thereby also the possibility of a light gluino. Depending on the photino mass, we exclude the R0 in the mass and lifetime ranges of 1.2 -- 4.6 GeV and 2E-10 -- 7E-4 seconds, respectively. (To Appear in Phys. Rev. Lett.)Comment: Documentstyle aps,epsfig,prl (revtex), 6 pages, 7 figure

Measurement of the branching ratio of pi^0 -> e^+e^- using K_L -> 3 pi^0 decays in flight

The branching ratio of the rare decay pi^0 -> e^+e^- has been measured in E799-II, a rare kaon decay experiment using the KTeV detector at Fermilab. The pi^0's were produced in fully-reconstructed K_L -> 3 pi^0 decays in flight. We observed 275 candidate pi^0 -> e^+e^- events, with an expected background of 21.4 +- 6.2 events which includes the contribution from Dalitz decays. We measured BR(pi^0 -> e^+e^-, x>0.95) = (6.09 +- 0.40 +- 0.24) times 10^{-8}, where the first error is statistical and the second systematic. This result is the first significant observation of the excess rate for this decay above the unitarity lower bound.Comment: New version shortened to PRL length limit. 5 pages, 4 figures. Published in Phys. Rev. Let

A Measurement of the KL Charge Asymmetry

We present a measurement of the charge asymmetry $\delta_L$ in the mode $K_L \to \pi^{\pm}e^{\mp}\nu$ based on 298 million analyzed decays. We measure a value of $\delta_L = (3322 \pm 58(stat) \pm 47(sys))\cdot 10^{-6}$, in good agreement with previous measurements and 2.4 times more precise than the current best published result. The result is used to place more stringent limits on CPT and $\Delta S = \Delta Q$ violation in the neutral kaon system.Comment: Submitted to Physical Review Letters, Dec 31, 2001. 4 pages, 4 figure

Search for the Decay K_L -> pi^0 nu nubar using pi^0 -> e^+ e^- gamma

We report on a search for the decay K_L -> pi^0 nu nubar, carried out as a part of E799-II, a rare K_L decay experiment at Fermilab. Within the Standard Model, the K_L -> pi^0 nu nubar decay is dominated by direct CP violating processes, and thus an observation of the decay implies confirmation of direct CP violation. Due to theoretically clean calculations, a measurement of B(K_L -> pi^0 nu nubar) is one of the best ways to determine the CKM parameter eta. No events were observed, and we set an upper limit B(K_L -> pi^0 nu nubar) < 5.9 times 10^-7 at the 90% confidence level.Comment: 5 pages, 4 figure

Light Gluino Search for Decays Containing pi+pi- or pi0 from a Neutral Hadron Beam at Fermilab

We report on two null searches, one for the spontaneous appearance of $\pi^+\pi^-$ pairs, another for a single $\pi^0$, consistent with the decay of a long-lived neutral particle into hadrons and an unseen neutral particle. For the lowest level gluon-gluino bound state, known as the $R^0$, we exclude the decays $R^0\to \pi^+\pi^-\tilde{\gamma}$ and $R^0\to \pi^0\tilde{\gamma}$ for the masses of $R^0$ and $\tilde{\gamma}$ in the theoretically allowed range. In the most interesting $R^0$ mass range, $\leq 3 GeV/c^2$, we exclude $R^0$ lifetimes from $3\times 10^{-10}$ seconds to as high as $10^{-3}$ seconds, assuming perturbative QCD production for the $R^0$.Comment: 15 pages, 7 figure

Observation of CP Violation in K(L)->pi+pi-e+e- Decays

We report the first observation of a manifestly CP violating effect in the K(L)->pi+pi-e+e- decay mode. A large asymmetry was observed in the distribution of these decays in the CP-odd and T-odd angle phi between the decay planes of the e+e- and pi+pi- pairs in the K(L) center of mass system. After acceptance corrections, the overall asymmetry is found to be 13.6+-2.5 (stat) +-1.2 (syst)%. This is the largest CP-violating effect yet observed integrating over the entire phase space of a mode and the first such effect observed in an angular variable.Comment: 4 pages 4 figures submitted to pr

Precise Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System

We present precise tests of CP and CPT symmetry based on the full dataset of K to pipi decays collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This dataset contains 16 million K to 2pi0 and 69 million K to pi+pi- decays. We measure the direct CP violation parameter Re(epsilon'/epsilon) = (19.2 pm 2.1)x10-4. We find the KL-KS mass difference Deltam = (5270 pm 12)x10^6 hbar/s and the KS lifetime tauS = (89.62 pm 0.05)x10-12 s. We also measure several parameters that test CPT invariance. We find the difference between the phase of the indirect CP violation parameter, epsilon, and the superweak phase, phi_epsilon - phi_SW = (0.40 pm 0.56) degrees. We measure the difference of the relative phases between the CP violating and CP conserving decay amplitudes for K to pi+pi- (phi+-) and for K to 2pi0 (phi00), Delta phi = (0.30 pm 0.35) degrees. From these phase measurements, we place a limit on the mass difference between K0 and K0bar, DeltaM < 4.8 x 10-19 GeV/c^2 at 95% C.L. These results are consistent with those of other experiments, our own earlier measurements, and CPT symmetry.Comment: 28 pages, 30 figures; removed extra figur

A New Measurement of the Radiative Ke3 Branching Ratio and Photon Spectrum

We present a preliminary report on a new measurement of the radiative neutral Ke3 branching ratio and the first study of the photon spectrum in this decay. We find BR(Ke3g, E*_g>30 GeV, Th*_eg>20 deg)/BR(Ke3) = 0.911+-0.009(stat)+0.021-0.010(syst)%. Our measurement of the spectrum is consistent with inner bremsstrahlung only as the source of photons at the 2 sigma level.Comment: 5 pages, 4 figures, proceedings paper from Meson 2000, Cracow, Poland, May 200