3,084 research outputs found

    No Sommerfeld resummation factor in e+e- -> ppbar ?

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    The Sommerfeld rescattering formula is compared to the e+e- -> ppbar BaBar data at threshold and above. While there is the expected Coulomb enhancement at threshold, two unexpected outcomes have been found: |G^p (4M_p^2)|= 1, like for a pointlike fermion, and moreover data show that the resummation factor in the Sommerfeld formula is not needed. Other e+e- -> baryon-antibaryon cross sections show a similar behavior near threshold.Comment: 9 pages, 6 figure

    Growth Trajectory and Adult Height in Children with Nonclassical Congenital Adrenal Hyperplasia

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    Background: Children with nonclassical congenital adrenal hyperplasia (NCCAH) often present increased growth velocity secondary to elevation of adrenal androgens that accelerates bone maturation and might compromise adult height (AH). Objective: The aim of the study was to analyze prognostic factors affecting growth trajectory (GT) and AH in children with NCCAH. Methods: The study was a retrospective, multicentric study. The study population consisted of 192 children with a confirmed molecular diagnosis of NCCAH, followed by pediatric endocrinology centers from diagnosis up to AH. Clinical records were collected and analyzed. AH (standard deviation score; SDS), pubertal growth (PG) (cm), GT from diagnosis to AH (SDS), and AH adjusted to target height (TH) (AH-TH SDS) were evaluated as outcome indicators using stepwise linear regression models. Results: The stepwise linear regression analysis showed that AH and AH-TH were significantly related to chronological age (CA) (p = 0.008 and 0.016), bone age (BA)/CA ratio (p = 0.004 and 0.001), height (H) (p < 0.001 for both parameters) at NCCAH diagnosis, and TH (p = 0.013 and <0.001). PG was higher in males than in females (22.59 ± 5.74 vs. 20.72 ± 17.4 cm, p = 0.002), as physiologically observed, and was positively related to height (p = 0.027), negatively to BMI (p = 0.001) and BA/CA ratio (p = 0.001) at NCCAH diagnosis. Gender, genotype, biochemical data, and hydrocortisone treatment did not significantly impair height outcomes of these NCCAH children. Conclusions: The results of this study suggest that AH and GT of NCCAH patients are mainly affected by the severity of phenotype (CA, BA/CA ratio, and H) at the time of diagnosis. © 2020 S. Karger AG. All rights reserved

    The Extreme Energy Events HECR array: status and perspectives

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    The Extreme Energy Events Project is a synchronous sparse array of 52 tracking detectors for studying High Energy Cosmic Rays (HECR) and Cosmic Rays-related phenomena. The observatory is also meant to address Long Distance Correlation (LDC) phenomena: the network is deployed over a broad area covering 10 degrees in latitude and 11 in longitude. An overview of a set of preliminary results is given, extending from the study of local muon flux dependance on solar activity to the investigation of the upward-going component of muon flux traversing the EEE stations; from the search for anisotropies at the sub-TeV scale to the hints for observations of km-scale Extensive Air Shower (EAS).Comment: XXV ECRS 2016 Proceedings - eConf C16-09-04.

    Proposal for taking data with the KLOE-2 detector at the DAΊ\PhiNE collider upgraded in energy

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    This document reviews the physics program of the KLOE-2 detector at DAΊ\PhiNE upgraded in energy and provides a simple solution to run the collider above the ϕ\phi-peak (up to 2, possibly 2.5 GeV). It is shown how a precise measurement of the multihadronic cross section in the energy region up to 2 (possibly 2.5) GeV would have a major impact on the tests of the Standard Model through a precise determination of the anomalous magnetic moment of the muon and the effective fine-structure constant at the MZM_Z scale. With a luminosity of about 103210^{32}cm−2^{-2}s−1^{-1}, DAΊ\PhiNE upgraded in energy can perform a scan in the region from 1 to 2.5 GeV in one year by collecting an integrated luminosity of 20 pb−1^{-1} (corresponding to a few days of data taking) for single point, assuming an energy step of 25 MeV. A few years of data taking in this region would provide important tests of QCD and effective theories by γγ\gamma\gamma physics with open thresholds for pseudo-scalar (like the ηâ€Č\eta'), scalar (f0,f0â€Čf_0,f'_0, etc...) and axial-vector (a1a_1, etc...) mesons; vector-mesons spectroscopy and baryon form factors; tests of CVC and searches for exotics. In the final part of the document a technical solution for the energy upgrade of DAΊ\PhiNE is proposed.Comment: 19 pages, 8 figure

    A Study of Time-Dependent CP-Violating Asymmetries and Flavor Oscillations in Neutral B Decays at the Upsilon(4S)

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    We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data sample consists of 29.7 fb−1{\rm fb}^{-1} recorded at the ΄(4S)\Upsilon(4S) resonance and 3.9 fb−1{\rm fb}^{-1} off-resonance. One of the neutral B mesons, which are produced in pairs at the ΄(4S)\Upsilon(4S), is fully reconstructed in the CP decay modes J/ψKS0J/\psi K^0_S, ψ(2S)KS0\psi(2S) K^0_S, χc1KS0\chi_{c1} K^0_S, J/ψK∗0J/\psi K^{*0} (K∗0→KS0π0K^{*0}\to K^0_S\pi^0) and J/ψKL0J/\psi K^0_L, or in flavor-eigenstate modes involving D(∗)π/ρ/a1D^{(*)}\pi/\rho/a_1 and J/ψK∗0J/\psi K^{*0} (K∗0→K+π−K^{*0}\to K^+\pi^-). The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample finds Δmd=0.516±0.016(stat)±0.010(syst)ps−1\Delta m_d = 0.516\pm 0.016 {\rm (stat)} \pm 0.010 {\rm (syst)} {\rm ps}^{-1}. The value of the asymmetry amplitude sin⁥2ÎČ\sin2\beta is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged B0B^0 decays in the CP-eigenstate modes. We find sin⁥2ÎČ=0.59±0.14(stat)±0.05(syst)\sin2\beta=0.59\pm 0.14 {\rm (stat)} \pm 0.05 {\rm (syst)}, demonstrating that CP violation exists in the neutral B meson system. (abridged)Comment: 58 pages, 35 figures, submitted to Physical Review

    Branching fraction and form-factor shape measurements of exclusive charmless semileptonic B decays, and determination of |V_{ub}|

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    We report the results of a study of the exclusive charmless semileptonic decays, B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu, B^+ --> eta l^+ nu and B^+ --> eta^' l^+ nu, (l = e or mu) undertaken with approximately 462x10^6 B\bar{B} pairs collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of q^2, the square of the momentum transferred to the lepton-neutrino pair, for B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu and B^+ --> eta l^+ nu. From these distributions, we extract the form-factor shapes f_+(q^2) and the total branching fractions BF(B^0 --> pi^- l^+ nu) = (1.45 +/- 0.04_{stat} +/- 0.06_{syst})x10^-4 (combined pi^- and pi^0 decay channels assuming isospin symmetry), BF(B^+ --> omega l^+ nu) = (1.19 +/- 0.16_{stat} +/- 0.09_{syst})x10^-4 and BF(B^+ --> eta l^+ nu) = (0.38 +/- 0.05_{stat} +/- 0.05_{syst})x10^-4. We also measure BF(B^+ --> eta^' l^+ nu) = (0.24 +/- 0.08_{stat} +/- 0.03_{syst})x10^-4. We obtain values for the magnitude of the CKM matrix element V_{ub} by direct comparison with three different QCD calculations in restricted q^2 ranges of B --> pi l^+ nu decays. From a simultaneous fit to the experimental data over the full q^2 range and the FNAL/MILC lattice QCD predictions, we obtain |V_{ub}| = (3.25 +/- 0.31)x10^-3, where the error is the combined experimental and theoretical uncertainty.Comment: 35 pages, 14 figures, submitted to PR

    Observation of time-reversal violation in the B0 meson system

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    The individually named authors work collectively as The BABAR Collaboration. Copyright @ 2012 American Physical Society.Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B0 or BÂŻÂŻÂŻ0), and J/ψK0L or ccÂŻK0S final states (referred to as B+ or B−), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, BÂŻÂŻÂŻ0→B− and B−→BÂŻÂŻÂŻ0, as a function of the time difference between the two B decays. Using 468×106 BBÂŻÂŻÂŻ pairs produced in ΄(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS+T=−1.37±0.14(stat)±0.06(syst) and ΔS−T=1.17±0.18(stat)±0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG(Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union), the A. P. Sloan Foundation (USA) and the Binational Science Foundation (USA-Israel)
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