Signals of new physics in global event properties inppcollisions in the TeV energy domain

Abstract

In the framework of the weighted superposition mechanism of different classes of minimum bias events (or substructures), described by the negative binomial multiplicity distribution, in possible scenarios for pp collisions in the TeV energy domain, we explore global properties of an eventual new class of events, characterised by high hadron and clan densities, to be added to the soft (without minijets) and semihard (with minijets) ones. It turns out that the main signal of the mentioned new physical expectations at 14 TeV c.m. energy would be an "elbow structure" in the tail of the total charged particle multiplicity distribution in complete disagreement with the second shoulder structure predicted by Pythia Monte Carlo calculations: a challenging problem for new experimental work.

Density saturation and the decrease of the normalised width of the multiplicity distribution in high energy pp collisions

“…k −1 = a + b ln n in [20], and the Pythia Monte Carlo [22], respectively dotted line and cross in Fig. 3c) give a monotonically decreasing k; for a discussion of the situation in which k continues to decrease at high energy and reaches values smaller than 1, see [21].…”

Clan Structure Analysis and QCD Parton Showers in Multiparticle Dynamics: An Intriguing Dialog Between Theory and Experiment

“…This violation of the virtuality conservation law spoils of course the validity of the energy-momentum conservation law, which, in the SPS model, uniquely determines the rapidity of a produced parton, given its virtuality and the virtuality and rapidity of its germane parton -see Eq. (108). In the GSPS model the two produced partons at each splitting are independent both in virtuality and in rapidity; however, the rapidity of each parton is bounded by the extension of phase-space fixed by its virtuality and the virtuality of the parent parton:…”

Signals of new physics in global event properties in pp collisions in the TeV energy domain: rapidity intervals

“…In [1] we concluded that an early occurrence of the limitN sh → 1 in FPS is of particular interest and leads in our framework to the onset of a new class of events with quite remarkable properties controlled by k th < 1, the effective benchmark of the new class of events.…”

“…4 are shown the three components and their superposition predicted by Pythia at 14 TeV in the interval |η| < 0.9. We have taken the results from [1], where Pythia version 6.210 [8] was run with default parameters using model 4 with a double Gaussian matter distribution. This set-up gives a reasonable description of lower energy MD data.…”

“…energy of a new class of events [1]. The aim of the present paper is to extend our study from full phase-space (FPS) to pseudo-rapidity intervals which will become experimentally accessible with the LHC detectors.…”