Molecular effects on antiproton capture by<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and the states of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mover><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover></mml:mrow></mml:mrow><mml:mi>p

Cohen, James S.

doi:10.1103/physreva.56.3583

Cited by 87 publications

(86 citation statements)

References 29 publications

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“…From this energy downward the probability for capture, which rises exponentially with decreasing energy (Cohen, 1983), reaches the order of magnitude of the probability for further energy loss. Two views of the capture process have become familiar, the semiclassical and the fully quantum-mechanical picture.…”

Section: The Formation Of Antiprotonic Atomsmentioning

confidence: 99%

“…The description of the p interaction with the atomic or molecular electrons, however, is based on quantummechanical calculations with the atomic electrons usually assumed to be a degenerate electron gas; for the lightest elements the kinematics of the individual electrons may be calculated directly. Although few calculations have been performed for antiprotons (Beck et al, 1993;Cohen, 1997), the results for muons can easily be transferred to p by appropriate kinematic scaling factors.…”

Section: The Formation Of Antiprotonic Atomsmentioning

confidence: 99%

“…The (Leon and Miller, 1977). most recent include a calculation based on quantum coupling equations performed by Dolinov et al (1989) and two quasiclassical approaches: Beck et al (1993) have developed a theory for the atomic capture of p in He and very recently Cohen (1997) devised a corresponding theory for p capture in hydrogen molecules.…”

Section: The Formation Of Antiprotonic Atomsmentioning

confidence: 99%

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Forty years of antiprotons

Eades

Hartmann

1999

Rev. Mod. Phys.

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The discovery of the antiproton some 40 years ago and the almost synchronous fall of parity (P) and charge conjugation (C) symmetries were soon followed by the realization that CPT rather than C invariance is the fundamental symmetry connecting matter and antimatter, and that consequently any measurement of the antiproton's properties can be interpreted as a test of that symmetry. It is the latter view of the antiproton, as an object of study in its own right, rather than as a means to such other ends as the production of gauge bosons and meson resonances, that is presented here. The authors review the technical steps that have led from the handful of antiprotons observed by Chamberlain, Segrè , Wiegand, and Ypsilantis to the intense, high-quality beams available today and show how the state of rest and isolation required for high precision measurements of their properties can be achieved by confining them in electromagnetic traps or in their microscopic counterparts, exotic atoms. The test bench role of antiprotons and antihydrogen atoms for both CPT symmetry and the gravitational weak equivalence principle is discussed, and the body of experimental results obtained since 1955 critically reviewed from this standpoint. Future experiments are then discussed in the light of the closure of the CERN Low Energy Antiproton Ring (LEAR), its replacement in 1999 by the Antiproton Decelerator (AD), and the likely antiproton source at the Japan Hadron Facility.[S0034-6861(99)00401-8] CONTENTS

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Section: The Formation Of Antiprotonic Atomsmentioning

confidence: 99%

Section: The Formation Of Antiprotonic Atomsmentioning

confidence: 99%

Section: The Formation Of Antiprotonic Atomsmentioning

confidence: 99%

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Forty years of antiprotons

Eades

Hartmann

1999

Rev. Mod. Phys.

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“…The main quantum number of 7 Be * X state whose binding energy is nearly equal to that of the GS 7 Be 3+ is n eq ∼113. We note that the reaction 7 Be 3+ +X − → 7 Be * X + e − is similar to the reaction H+p → pp + e − , where pp is the protonium consisting of a proton and an antiproton [53][54][55] since the following three characters are shared by the two reactions. Firstly, components related to the reaction are two heavy particles and a light electron.…”

mentioning

confidence: 85%

“…In this case, therefore, an efficient formation of the 7 Be X GS prefers a direct production of lower energy states at the 7 Be * X formation reaction or their production at the first photo-emission after the formation of 7 Be * X excited states. The first case is, however, not expected to operate effectively by an analogy of protonium formation dominantly producing states of large main quantum numbers n > ∼ n eq which correspond to small binding energies [54].We note that the 7 Be nucleus has been assumed to be a point charge particle in this work. Binding energies of A X atomic GS can, however, be significantly smaller than those estimated in the assumption of point charge nuclei since Bohr radii for the A X are of nuclear dimensions ∼ O(fm) [27,35,37].…”

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confidence: 93%

Be7charge exchange betweenBe3+7ion and an exotic long-lived negati

et al. 2013

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The existence of an exotic long-lived negatively charged massive particle, i.e., X − , during big bang nucleosynthesis can affect primordial light element abundances. Especially, the final abundance of 7 Li, mainly originating from the electron capture of 7 Be, has been suggested to reduce by the 7 Be destruction via the radiative X − capture of 7 Be followed by the radiative proton capture of the bound state of 7 Be and X − ( 7 BeX ). We suggest a new route of 7 BeX formation, that is the 7 Be charge exchange at the reaction of 7 Be 3+ ion and X − . The formation rate depends on the number fraction of 7 Be 3+ ion, the charge exchange cross section of 7 Be 3+ and the probability that produced excited states 7 Be * X are converted to the ground state. We estimate respective quantities affecting the 7 BeX formation rate, and find that this reaction pathway can be more important than ordinary radiative recombination of 7 Be and X − . The effect of the charge exchange reaction is then shown in a latest nuclear reaction network calculation. Quantum physical model calculations for related reactions are needed to precisely estimate the efficiency of this pathway in future.PACS numbers: 26.35.+c, 95.35.+d, 98.80.Cq, 98.80.Es I. INTRODUCTIONNew physics operating during the big bang nucleosynthesis (BBN) can be probed by observed light element abundances. Possible indications of new physics come from discrepancies between primordial abundances of 6 Li and 7 Li predicted in standard BBN (SBBN) model and those inferred from observations of metal-poor stars (MPSs). These MPSs exhibit a plateau-like abundance ratio, 7 Li/H = (1 − 2) × 10 −10 at low metallicities of [Fe/H]> −3 [1][2][3][4][5][6][7][8][9][10][11][12][13][14], and much lower at extremely low metallicities of [Fe/H]< −3 [15,16] [79]. The plateau abundance is a factor of 2-4 lower than the SBBN prediction for the baryon-to-photon ratio determined from the observation of the cosmic microwave background radiation with Wilkinson Microwave Anisotropy Probe (WMAP) (e.g., 7 Li/H=(5.24 +0.71−0.67 ) × 10 −10 [17]). This discrepancy indicates a need of some mechanism to decrease the 7 Li abundance. Although astrophysical processes such as the combination of atomic and turbulent diffusion in stellar atmospheres [18,19] may be a cause of the observed abundances, this is not yet established [20].In recent spectroscopic observations of MPSs, the lithium isotopic ratio of 6 Li/ 7 Li is also measured. A possible plateau abundance of 6 Li/H∼ 6 × 10 −12 has * Electronic address: motohiko@kau.ac.kr † Electronic address: kyungsik@kau.ac.kr ‡ Electronic address: cheoun@ssu.ac.kr § Electronic address: kajino@nao.ac.jp ¶ Electronic address: y.k@m.tohoku.ac.jp been suggested [4], which is about 1000 times higher than the SBBN prediction. Since an effect of convective motions in stellar atmospheres could cause asymmetries in atomic line profiles and consequently leads to an erroneous estimation of 6 Li abundance [21], the effect should be estimated. Even including this effect, high 6 Li ...

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Ionization of Atoms by Antiproton Impact

Macek

Electron Scattering

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Molecular effects on antiproton capture byH2and the states ofp¯p

Cited by 87 publications

References 29 publications

Forty years of antiprotons

Forty years of antiprotons

Be7charge exchange betweenBe3+7ion and an exotic long-lived negati

Ionization of Atoms by Antiproton Impact

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