Probe Higgs potential via multi-Higgs boson final states at hadron colliders

I summarize some results related with the determination of the Higgs potential, including a hadron-level Monte Carlo study of the sensitivity of Higgs boson pair production via the [Formula: see text] channel with the final state [Formula: see text] and the sensitivity study on the triple Higgs boson final state via [Formula: see text] in a 100 TeV collider.

Hadron diffractive production at ultrahigh energies and shadow effects

Shadow effects at collisions of hadrons with light nuclei at high energies were subject of scientific interest of V.N. Gribov, first, we mean his study of the hadron-deuteron scattering, see Sov. Phys. JETP 29, 483 (1969) [Zh. Eksp. Teor. Fiz. 56, 892 (1969)] and discovery of the reinforcement of shadowing due to inelastic diffractive rescatterings. It turns out that the similar effect exists on hadron level though at ultrahigh energies. Diffractive production is considered in the ultrahigh energy region where pomeron exchange amplitudes are transformed into black disk ones due to rescattering corrections. The corresponding corrections in hadron reactions [Formula: see text] with small momenta transferred ([Formula: see text], [Formula: see text]) are calculated in terms of the [Formula: see text]-matrix technique modified for ultrahigh energies. Small values of the momenta transferred are crucial for introducing equations for amplitudes. The three-body equation for hadron diffractive production reaction [Formula: see text] is written and solved precisely in the eikonal approach. In the black disk regime final state scattering processes do not change the shapes of amplitudes principally but dump amplitudes by a factor [Formula: see text]; initial state rescatterings result in additional factor [Formula: see text]. In the resonant disk regime initial and final state scatterings damp strongly the production amplitude that corresponds to [Formula: see text] at [Formula: see text] in this mode.

Consistent simulation of direct-photon production in hadron collisions including associated two-jet production

We have developed an event generator for direct-photon production in hadron collisions, including associated 2-jet production in the framework of the GR@PPA event generator. The event generator consistently combines [Formula: see text] + 2-jet production processes with the lowest-order [Formula: see text] + jet and photon-radiation (fragmentation) processes from quantum chromodynamics (QCD) 2-jet production using a subtraction method. The generated events can be fed to general-purpose event generators to facilitate the addition of hadronization and decay simulations. Using the obtained event information, we can simulate photon isolation and hadron-jet reconstruction at the particle (hadron) level. The simulation reasonably reproduces measurement data obtained at the large hadron collider (LHC) concerning not only the inclusive photon spectrum, but also the correlation between the photon and jet. The simulation implies that the contribution of the [Formula: see text] + 2-jet is very large, especially in low photon-[Formula: see text] ([Formula: see text] 50 GeV) regions. Discrepancies observed at low [Formula: see text], although marginal, may indicate the necessity for the consideration of further higher-order processes. Unambiguous particle-level definition of the photon-isolation condition for the signal events is desired to be given explicitly in future measurements.

Multiple Gluon Effects in $q+\bar{q}\rightarrow t+\bar{t}+X$ at FNAL Energies: Semi-Analytical Results

We apply our Yennie–Frautschi–Suura exponentiated cross-section formulas for the parton process [Formula: see text] to the process [Formula: see text] at FNAL energies, where G is a QCD gluon. We use semi-analytical methods to compute the ratio [Formula: see text], where [Formula: see text] is our soft gluon YFS exponentiated cross-section and [Formula: see text] is the Born cross-section. For mt=0.176(0.199) TeV, we get r expt =1.65(1.48), respectively, for q=u for example. We show that these parton level results, when properly synthesized with the DGLAP structure function evolution, lead to the conclusion that the YFS exponentiated hadron level cross-section for [Formula: see text] is increased by ~0.6–0.8% beyond the Born cross-section due to the re-summation of soft gluon effects beyond those in the exact [Formula: see text] correction when mt=176 GeV. These results are not inconsistent with the recent observations by CDF and D0.

HYPERON RADIATIVE DECAYS

We review the experimental and theoretical status of weak radiative hyperon decays. Our discussion centers on a controversy over the validity of Hara’s theorem, which was originally expected to be respected by these decays. After presenting the hadron level theorem we describe experiments that have provided convincing evidence against its applicability to these decays. In the theoretical part we juxtapose the hadron level and quark level approaches and discuss the violation of Hara’s theorem in the latter. We review quark model phenomenology, which offers a promising description of experimental data. Measurements that should be made to settle the theoretical controversy are pinpointed. The importance of radiative hyperon decays in understanding the nonlocal composite nature of hadrons is stressed.