Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · nucl-th/9707008

Coherent Photons and Pomerons in Heavy Ion Collisions

Spencer Klein·Evan Scannapieco
View original source ↗Read source document ↗Export metadata ↓

Abstract

Ultrarelativistic heavy ion beams carry large electromagnetic and strong absorptive fields, allowing exploration of a variety of physics. Two-photon, photon-Pomeron, and double Pomeron interactions can probe a huge variety of couplings and final states. RHIC will be the first heavy ion accelerator energetic enough to produce hadronic final states via coherent couplings. Virtual photons from the nuclear EM fields can interact in two-photon interactions, which can be exploited to study many particle spectroscopy and QCD topics. Because the photon flux scales as $Z^2$, Two-photon luminosities are large up to an energy of about γ\hbar c/R~ 3 GeV/c. Photon-Pomeron interactions are sensitive to how different vector mesons, including the $J/ψ$, interact with nuclear matter. $PP$ collisions rates are sensitive to the range of the Pomeron. Signals can be separated from backgrounds by using cuts on final state isolation (rapidity gaps) and $p_\perp$. We present Monte Carlo studies of different backgrounds, showing that representative signals can be extracted with good rates and signal to noise ratios.

Explore related subjects

nucl-th

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Spencer Klein, Evan Scannapieco. 1997-07-03. Coherent Photons and Pomerons in Heavy Ion Collisions. https://doi.org/10.1063/1.54320

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Wigner distribution modeling of nuclear state in NuWro Monte Carlo event generator

We develop a method to use the Wigner distribution (WD) description of the nuclear initial state of $^{12}$C, $^{16}$O, $^{40}$Ar, and $^{56}$Fe for quasielastic scattering in the NuWro Monte Carlo event generator. We propose two different algorithms to deal with the problem of negative values of the WDs. In our treatment, finite-nucleus WDs provide a correlation between the position and the momentum of bound nucleons that is very different from what is assumed in the standard approaches based on the Fermi gas model and spectral functions. We show that the use of WDs leads to effects that can be measured experimentally and may be relevant for future neutrino oscillation experiments.

nucl-th↗
arXiv2026

Effects of in-medium $NN$ inelastic cross sections and the high-momentum tail of nucleon momentum distributions on pion production in heavy-ion collisions

Pion production in intermediate-energy heavy-ion collisions (HICs) provides a sensitive probe of the nuclear equation of state and of the isospin dependence of reaction dynamics. In particular, pion production near threshold is strongly affected by the nucleon-nucleon ($NN$) inelastic cross sections and by the high-momentum components of the nucleon momentum distribution. To explore the influence of these two ingredients on pion production and charged-pion ratios, the in-medium $NN$ inelastic cross sections calculated within the relativistic Boltzmann-Uehling-Uhlenbeck transport theory and the short-range correlation induced high-momentum tail (HMT) are introduced into the Ultra-relativistic Quantum Molecular Dynamics model. By simulating Au+Au collisions at intermediate energies, we find that the in-medium modification of the $NN$ inelastic cross sections suppresses the pion multiplicity by reducing the probability of $NΔ$ production in dense matter. The HMT, on the other hand, enhances the high-momentum components of nucleons and modifies the available energy in individual $NN$ collisions, thereby affecting $NN\rightarrow NΔ$ reactions and the subsequent pion production. With the simultaneous inclusion of these two effects, the pion yields and the $π^-/π^+$ ratio data can be better reproduced. These results highlight the importance of both the in-medium reaction cross sections and short-range correlation induced high-momentum components in pion production in intermediate energy HICs.

nucl-th↗
arXiv2026

Neutron star cooling with medium-modified Urca rates

We study the effects of in-medium modification of the elementary cooling processes on observable properties of isolated neutron stars. We deduce the neutron star mass distributions compatible with the cooling analysis and compare with current theoretical models. We conclude that current cooling data require fast direct Urca cooling, moderated by proton superfluidity, to be active in most neutron stars, and that the DU onset threshold must lie below canonical masses. In that case medium modifications of modified Urca rates are practically insignificant, but the nn Bremsstrahlung rate plays a dominant role.

nucl-th↗