Virtual corrections to gg → ZH via a transverse momentum expansion

We compute the next-to-leading virtual QCD corrections to the partonic cross section of the production of a Higgs boson in association with a Z boson in gluon fusion. The calculation is based on the recently introduced method of evaluating the amplitude via an expansion in terms of a small transverse momentum. We generalize the method to the case of different masses in the final state and of a process not symmetric in the forward-backward direction exchange. Our analytic approach gives a very good approximation (better than percent) of the partonic cross section in the center of mass energy region up to ∼ 750 GeV, where at the LHC ∼ 98% of the total hadronic cross section is concentrated.

Leading components in forward elastic hadron scattering: Derivative dispersion relations and asymptotic uniqueness

Forward amplitude analyses constitute an important approach in the investigation of the energy dependence of the total hadronic cross-section [Formula: see text] and the [Formula: see text] parameter. The standard picture indicates for [Formula: see text] a leading log-squared dependence at the highest c.m. energies, in accordance with the Froissart–Lukaszuk–Martin bound and as predicted by the COMPETE Collaboration in 2002. Beyond this log-squared (L2) leading dependence, other amplitude analyses have considered a log-raised-to-gamma form [Formula: see text], with [Formula: see text] as a real free fit parameter. In this case, analytic connections with [Formula: see text] can be obtained either through dispersion relations (derivative forms), or asymptotic uniqueness (Phragmén–Lindelöff theorems). In this work, we present a detailed discussion on the similarities and mainly the differences between the Derivative Dispersion Relation (DDR) and Asymptotic Uniqueness (AU) approaches and results, with focus on the [Formula: see text] and L2 leading terms. We also develop new Regge–Gribov fits with updated dataset on [Formula: see text] and [Formula: see text] from [Formula: see text] and [Formula: see text] scattering, including all available data in the region 5 GeV–8 TeV. The recent tension between the TOTEM and ATLAS results at 7 TeV and mainly at 8 TeV is discussed and considered in the data reductions. Our main conclusions are the following: (1) all fit results present agreement with the experimental data analyzed and the goodness-of-fit is slightly better in case of the DDR approach; (2) by considering only the TOTEM data at the LHC region, the fits with L[Formula: see text] indicate [Formula: see text] (AU approach) and [Formula: see text] (DDR approach); (3) by including the ATLAS data the fits provide [Formula: see text] (AU) and [Formula: see text] (DDR); (4) in the formal and practical contexts, the DDR approach is more adequate for the energy interval investigated than the AU approach. A pedagogical and detailed review on the analytic results for [Formula: see text] and [Formula: see text] from the Regge–Gribov, DDR and AU approaches is presented. Formal and practical aspects related to forward amplitude analyses are also critically discussed.

HADRONIC CROSS SECTION MEASUREMENTS AT SND

The preliminary results on multihadron processes obtained with the SND detector at the e+e− collider VEPP-2000 in the energy range from 1 to 2 GeV are presented. The results are interesting in connection with their contribution to the total hadronic cross section, the muon g-2 and a possibility to study excited vector mesons properties. The nucleon anti-nucleon production was also studied.