Coherent electromagnetic heavy ion reactions: (1) exact treatment of pair production and ionization; (2) mutual Coulomb dissociation

Some recent theoretical results on coherent electromagnetic processes in ultrarelativistic heavy ion reactions are surveyed.Comment: 4 pages, latex source, no figures, to appear in Proceedings of Quark Matter '9

Coulomb potential from a particle in uniform ultrarelativistic motion

The Coulomb potential produced by an ultrarelativistic particle (such as a heavy ion) in uniform motion is shown in the appropriate gauge to factorize into a longitudinal Dirac delta function of (z - t) times the simple two dimensional potential solution in the transverse direction. This form makes manifest the source of the energy independence of the interaction.Comment: 5 pages, latex, revtex source, no figure

The electromagnetic interaction of ultrarelativistic heavy ions

The validity of a delta-function approximation for the electromagnetic interaction of relativistic heavy ions is investigated. The production of e+e- pairs, with electron capture, is used as a test of the approximation.Comment: 11 pages, 3 figure

Local Delivery of CTLA-4 Blockade Inhibits Growth of Pancreatic Tumors

Immune checkpoint blockade has demonstrated great potential in activating antitumor immunity. Ipilimumab is a monoclonal antibody which targets cytotoxic T-lymphocyte antigen-4. CTLA-4 belongs to the CD28 class of receptors and is found on the surface of CD4+ and CD8+ T cells. CTLA-4 acts to suppress the immune system when bound to CD80 and CD86 receptors on antigen presenting cells. Ipilimumab, or anti-CTLA-4, has shown to be effective in significantly extending the survival of patients with metastatic melanoma. However, systemic delivery of Ipilimumab also induces significant side effects such as: colitis, dermatitis, uveitis, and hypophysitis. In order to minimize toxicity, we and others have hypothesized that intratumoral administration of anti-CTLA-4 at a lower dose can have the same antitumor efficacy as systemic delivery but without the toxicity. This work begins with an investigational pilot study to determine the efficacy of anti-CTLA-4 by delivering 60 µg of anti-CTLA-4 to a group of mice and measuring the tumor growths when compared to an untreated control group. Once efficacy had been demonstrated, a dosing study was conducted to identify an optimal intratumoral dosage delivered to murine models. The groups were given doses of either 30 µg, 60 µg, or 120 µg. From this study, the 60 µg group had the lowest average tumor size of 300 mm3. Our lab has previously demonstrated that IL-12 co-formulated with chitosan has demonstrated prolonged intratumoral retention therefore, 60 µg of anti-CTLA was co-formulated with a chitosan solution investigate the efficacy in a delivery vehicle. Finally, 60 µg of anti-CTLA-4 was delivered in a proprietary hydrogel alone and with Interleukin-12 to examine the effects of controlled release

Some exact analytical results and a semi-empirical formula for single electron ionization induced by ultrarelativistic heavy ions

The delta function gauge of the electromagnetic potential allows semiclassical formulas to be obtained for the probability of exciting a single electron out of the ground state in an ultrarelativistic heavy ion reaction. Exact formulas have been obtained in the limits of zero impact parameter and large, perturbative, impact parameter. The perturbative impact parameter result can be exploited to obtain a semi-empirical cross section formula of the form, sigma = A ln(gamma) + B, for single electron ionization. A and B can be evaluated for any combination of target and projectile, and the resulting simple formula is good at all ultrarelativistic energies. The analytical form of A and B elucidates a result previously found in numerical calculations: scaled ionization cross sections decrease with increasing charge of the nucleus being ionized. The cross section values obtained from the present formula are in good agreement with recent CERN SPS data from a Pb beam on various nuclear targets.Comment: 14 pages, latex, revtex source, no figure

Heavy Ion e+ e- Pairs to All Orders in Z alpha

The heavy ion cross section for continuum e+ e- pair production has been calculated to all orders in Z alpha. Comparison is made with available CERN SPS and RHIC STAR data. Computed cross sections are found to be reduced from perturbation theory with increasing charge of the colliding heavy ions and for all energy and momentum regions investigated. Au or Pb total cross sections are reduced by 28% (SPS), 17% (RHIC),and 11% (LHC). For very high energy (E_e+, E_e- > 3 GeV) forward pairs at LHC the reduction from perturbation theory is a bit larger (17%). Use of zero degree calorimeter triggering (and thus small impact parameter weighting) makes impact parameter representation of exact pair production useful. Preliminary exact calculations in the zero impact parameter limit show a much larger reduction from perturbation theory (about 40%) at both RHIC and LHC.Comment: 4 pages, poster proceedings from Quark Matter 200

Higher Order QED Calculation of Ultrarelativistic Heavy Ion Production of mu+ mu- Pairs

A higher order QED calculation of the ultraperipheral heavy ion cross section for mu+ mu- pair production at RHIC and LHC is carried out. The so-called "Coulomb corrections" lead to an even greater percentage decrease of mu+ mu- production from perturbation theory than the corresponding decrease for e+ e- pair production. Unlike the e+ e- case, the finite charge distribution of the ions (form factor) and the necessary subtraction of impact parameters with matter overlap are significant effects in calculation an observable ultraperipheral mu+ mu- total cross section.Comment: 7 pages, 3 figures. Version expanded with explanatory text and two appendices on form factor treatmen

Pair production with electron capture in peripheral collisions of relativistic heavy ions

The production of electron-positron pairs with the capture of the electron in an atomic orbital is investigated for the conditions of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider LHC). Dirac wave functions for the leptons are used, taking corrections to orders of Z.alpha into account. The dependence on the transverse momentum transfer is studied and the accuracy of the equivalent photon approximation is discussed as a function of the nuclear charge.Comment: 4 postscript figure