Observation of exclusive charmonium production and gamma gamma ---> mu+mu- in p anti-p collisions at s**(1/2) = 1.96-TeV
Bibliographic record
Abstract
We have observed the reactions p + {bar p} {yields} p + X + {bar p}, with X being a centrally produced J/{psi}, {psi}(2S) or {chi}{sub c0}, and {gamma}{gamma} {yields} {mu}{sup +}{mu}{sup -}, in proton-antiproton collisions at {radical}s = 1.96 TeV using the Run II Collider Detector at Fermilab. The event signature requires two oppositely charged muons, each with pseudorapidity |{eta}| < 0.6, with M{sub {mu}{mu}} {element_of} [3.0; 4.0] GeV/c{sup 2} and either no other particles, or one additional photon, detected. The J/{psi} and the {psi}(2S) are prominent, on a continuum consistent with the QED process {gamma}{gamma} {yields} {mu}{sup +}{mu}{sup -}. Events with a J/{psi} and an associated photon candidate are consistent with exclusive {chi}{sub c0} production through double pomeron exchange. The exclusive vector meson production is as expected for elastic photoproduction, {gamma} + p {yields} J/{psi}({psi}(2S)) + p, which is observed here for the first time in hadron-hadron collisions. The cross sections d{sigma}/dy|y = 0 for p + {bar p} {yields} p + X + {bar p} with X = J/{psi},{psi}(2S) or {chi}{sub c0} are 3.92 {+-} 0.62 nb, 0.53 {+-} 0.14 nb, and 76 {+-} 14 nb respectively. The cross section for the continuum, with |{eta}({mu}{sup {+-}})| < 0.6, M{sub {mu}{mu}} {element_of} [3.0, 4.0] GeV/c{sup 2}, is {integral} d{sigma}/dM.d{eta}{sub 1}.d{eta}{sub 2} = 2.7 {+-} 0.5 pb, consistent with QED predictions. We put an upper limit on the cross section for odderon exchange in exclusive J/{psi} production: d{sigma}/dy|y = 0(J/{psi}{sub OIP}) < 2.3 nb at 95% C.L.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".