Physics of the FVTX

The FVTX upgrade will enhance the physics program of the PHENIX experiment in all of its main areas of study. The list below is taken from the FVTX Technical Design Reviw Document.

A+A collisions and the Quark Gluon Plasma:

  • Study of energy loss and flow of heavy quarks into very forward and backward rapidity regions using robust charm and bottom measurements over a broader x range than available with the barrel VTX detector alone and with greater precision than is possible with the muon detectors alone. This allows the extension of studies of the geometrical and dynamical effects of the hot-dense matter created in high-energy heavy ion collisions into the forward and backward rapidity regions and will allow for the first time separate measurements for charm and bottom.
  • Precise open charm and bottom measurements will provide a solid "denominator" for comparison with production of bound states of heavy quarks (J/Psi and Upsilon). These comparisons will allow for the isolation of common physics, e.g., initial-state effects such as those on the gluon structure function and physics that only affects the bound states, e.g., final-state absorption. These measurements will also provide strong constraints on production of J/Psi's from recombination by determining a precise open-charm cross section over a broad rapidity range.
  • Direct measurement of Upsilons at mid-rapidity will be possible by eliminating the large random backgrounds from light-meson decays. Will also improve the mass resolution and signal/background for J/Psi production and enable improved separation of the J/Psi from the Psi’.
  • Unambiguous measurement of the Drell-Yan and heavy-flavor dimuon continuum by separating background muons from light meson decays, muons from heavy flavor decay and prompt muons.
  • An accurate reaction plane measurement will be provided by the FVTX.
  • Flow in the forward and backward regions will be able to be measured.

p(d)+A collisions and small-x or gluon saturation physics:

  • The study of the gluon structure function modification in nuclei at small (and large) x values, where gluon saturation or shadowing (anti-shadowing) is thought to be important will be possible, by adding precision open charm and bottom measurements at forward rapidity.
  • Determine the initial state for AA collisions and provide a robust baseline for cold-nuclear matter effects in studies of hot-dense matter in heavy ion collisions, again by adding precision heavy flavor measurements at forward rapidity.
  • Help untangle the intricate physics of J/Psi and Upsilon production in cold nuclear matter by providing robust measurements of open-heavy quark production that can, by contrast, separate initial and final-state physics for these resonances.
  • Allow for a clean measurement of Drell-Yan which can further help untangle production issues for the J/Psi.

Polarized p+p collisions, and the contributions to the spin of the nucleon:

  • Provide an increased x range (up to x ˜ 0.2 and down to 10-3) over which the mostly unknown gluon polarization (Delta-G/G) can be determined through open heavy flavor measurements. Without the FVTX the range covered is likely to be insufficient to study the shape of any polarization or to determine its peak value.
  • Allow for a direct measurement of the spin asymmetry in bottom production, which is expected to be different from open charm and light hadrons, thus providing much-needed cross checks.
  • Add background rejection capabilities for W and Z bosons measurements (which give information about the sea-quark contributions to the spin) by rejecting muons from light and heavy hadron decays which contribute to the high pT muon spectra and by adding the possibility of event topology cuts.
  • Enable Drell-Yan asymmetry measurements, which can give information about the sea quark polarization distributions.