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Register a new userAnomalous dilepton production from the Dirac sea in p+p collisions
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Authors
Oscar Garcia-Montero
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In a recent work from the ALICE collaboration an excess of relatively soft dilepton pairs was reported in p+p collisions at $13$ TeV. In the report no satisfactory explanation was found via standard bremsstrahlung computations. In this letter, textit{anomalous} dilepton pairs are produced non-perturbatively from the back-reaction of the vacuum to a $qbar{q}$ pair, travelling back-to-back. The dilepton spectrum is computed by folding this rate with the cross-section for the process p+p$rightarrow qbar{q}$, which was computed using the framework of the Color Glass Condensate Effective Field Theory (CGC EFT) in the $k_perp$-factorized limit. The resulting spectra is compatible within uncertainties with the data, and moreover, provides exciting insight into the non-perturbative phenomena that ultra-soft electromagnetic radiation can probe.
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The DLS collaboration has recently completed a high statistics study of dilepton production at the Bevalac. In particular, we have measured dielectrons (e+e-) from p-p and p-d collisions to understand the basic dilepton production mechanisms in the energy range from 1.05 - 4.9 GeV. These data can be used to determine the basic processes which contribute to nucleon-nucleon dilepton production such as hadronic bremsstrahlung, vector meson processes, and hadronic Dalitz decay. The data show that a simple elastic bremsstrahlung calculation is insufficient to explain the data. Theoretical models are compared with the data. A new high statistics study of Ca-Ca at 1.05 A GeV has been made to study the collectivity of A-A collisions.
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