Non-perturbative QCD analysis of near-to-planar three-jet events

We present the analysis of the 1/Q-suppressed non-perturbative (NP) contribution to the cumulative out-of-event-plane momentum distribution in e+e- annihilation in the near-to-planar three-jet region. It complements our previous study of the perturbative (PT) distributions resummed to single logarithmic accuracy. Due to inter-jet soft gluon radiation, the NP contributions (as well as the PT distributions) are sensitive to the geometry (the angles between jets) and the colour structure of the underlying hard process (topology of the three-prong parton antenna). The results and techniques presented here could be extended to other multi-jet processes and, in particular, to hadron-hadron collisions.Comment: 53 pages, 4 figures, JHEP class include

QCD analysis of D-parameter in near-to-planar three-jet events

We present the QCD analysis of D-parameter distribution in near-to-planar 3-jet e+e- annihilation events. We derive the all-order resummed perturbative prediction and the leading power suppressed non-perturbative corrections both to the mean value and the distribution. Here non-perturbative corrections are larger than in 2-jet shape observables, so that higher order non-perturbative effects could be relevant. Experimental data (not yet available) are needed in order to cast light on this important point. The technique we develop aims at improving the accuracy of the theoretical description of multi-jet ensembles, in particular in hadron-hadron collisions.Comment: 26 pages, 6 figures, JHEP class include

QCD analysis of near-to-planar 3-jet events

Perturbative QCD analysis is presented of the cumulative out-of-plane momentum distribution in the near-to-planar e+e- annihilation events, K_out << Q. In this kinematical region multiple gluon radiation effects become essential. They are resummed with the single-logarithmic accuracy, which programme includes the 2-loop treatment of the basic radiation and matching with the exact O(alpha_s^2) result. Dedicated experimental analyses of 3-jet event characteristics are of special interest for the study of the non-perturbative confinement effects.Comment: 32 pages, 1 figure, JHEP class include

Organic and healthy: assessing the impact of claims and third-party certifications on premium price

Organic food consumption is steadily growing across a variety of product categories. While consumers are increasingly focused on the healthiness of the food they purchase, companies are experimenting alternative ways to communicate and guarantee the organic and health-related benefits of their products. This study explores the effect of different combinations of front-of-package (FoP) components on premium price. Specifically, we focus on the interaction and visual salience of FoP organic claims, health-related claims, and third-party organic certifications. Based on an analysis of grocery sales data and product packaging visuals, the study identifies FoP component combinations that could maximise premiums. We offer insights to marketing managers and companies involved in enhancing the communication of organic food benefits to consumers

Commercio di vicinato e resilienza

The sustainability of cities highly depends on city center viability and shopping street resilience. With the increasing number of shopping centers and the strong impact of e-commerce on existing retail systems, the major urban challenge has become maintaining a balance in the market. The governments have attempted to reverse these negative impacts by developing proactive policies and programs. Over the last 25 years schemes of Town Centre Management (Tcm) or like-Tcm initiatives have emerged as a practical response to ensure that towns are desirable and attractive places. Whilst most reviews of Tcm or like- Tcm programs to date have focused on their structure and operations, little attention has been given to the role of these schemes as a \uabcompetitive tool\ubb to safeguard and valorise the Sme retailers located in the city centre. This paper examines the impact of \uabDistretto del commercio \ubb \u2013 a like-Tcm scheme introduced by the Lombardy region (Italy) in the 2008 \u2013 on the Sme retailers during the economic crisis (2008-2017). Our analysis demonstrates that the \uabDistretto del commercio\ubb had a relevant positive effect on the shopping street resilience and city center viability. The size of the effect depends on the different typology of Distretto, the commercial competitiveness of the area and the structural variables of the territory

Leptons in the proton

As is the case for all light coloured Standard Model particles, also photons and charged leptons appear as constituents in ultrarelativistic hadron beams, and admit a parton density function (PDF). It has been shown recently that the photon PDF can be given in terms of the structure functions and form factors for electron-proton scattering. The same holds for lepton PDFs. In the present work we set up a calculation of the lepton PDFs at next-to-leading order, using the same data input needed in the photon case. A precise knowledge of the lepton densities allows us to study lepton-initiated processes even at a hadron collider, with all possible combinations of same-charge, opposite-charge, same-flavour, different-flavour leptons and leptons-quarks, most of which cannot be realized in any other forseable experiment. The lepton densities in the proton are extremely small, so that their contribution to Standard Model processes is generally shadowed by processes initiated by coloured partons. We will show, however, that there are cases where these processes can be relevant, giving rise to rare Standard Model signatures and to new production channels, that can enlarge the discovery potential of New Physics at the LHC and future high energy colliders with hadrons in the initial state

Lepton-Quark Collisions at the Large Hadron Collider

Processes commonly studied at the Large Hadron Collider (LHC) are induced by quarks and gluons inside the protons of the LHC beams. In this Letter, we demonstrate that, since protons also contain leptons, it is possible to target lepton-induced processes at the LHC as well. In particular, by picking a lepton from one beam and a quark from the other beam, we present for the first time a comprehensive analysis of resonant single leptoquark (LQ) production at a hadron collider. In the case of minimal scalar LQs, we derive novel bounds that arise from the LHC Run II considering all possible flavor combinations of an electron or a muon and an up (u), a down (d), a strange, or a charm quark. For the flavor combinations with a u or a d quark, the obtained limits represent the most stringent constraints to date on LQs of this type. The prospects of our method at future LHC runs are also explored. Given the discovery reach of the proposed LQ signature, we argue that dedicated resonance searches in final states featuring a single light lepton and a single light-flavor jet should be added to the exotics search canon of both the ATLAS and the CMS Collaborations

Scalar one-loop integrals for QCD

We construct a basis set of infra-red and/or collinearly divergent scalar one-loop integrals and give analytic formulas, for tadpole, bubble, triangle and box integrals, regulating the divergences (ultra-violet, infra-red or collinear) by regularization in $D=4-2\epsilon$ dimensions. For scalar triangle integrals we give results for our basis set containing 6 divergent integrals. For scalar box integrals we give results for our basis set containing 16 divergent integrals. We provide analytic results for the 5 divergent box integrals in the basis set which are missing in the literature. Building on the work of van Oldenborgh, a general, publicly available code has been constructed, which calculates both finite and divergent one-loop integrals. The code returns the coefficients of $1/\epsilon^2,1/\epsilon^1$ and $1/\epsilon^0$ as complex numbers for an arbitrary tadpole, bubble, triangle or box integral.Comment: 27 pages, 5 figures, associated fortran code available at http://qcdloop.fnal.gov/. New version corrects typographical error in Eq. 5.

MINLO: Multi-scale improved NLO

In the present work we consider the assignment of the factorization and renormalization scales in hadron collider processes with associated jet production, at next-to-leading order (NLO) in perturbation theory. We propose a simple, definite prescription to this end, including Sudakov form factors to consistently account for the distinct kinematic scales occuring in such collisions. The scheme yields results that are accurate at NLO and, for a large class of observables, it resums to all orders the large logarithms that arise from kinematic configurations involving disparate scales. In practical terms the method is most simply understood as an NLO extension of the matrix element reweighting procedure employed in tree level matrix element-parton shower merging algorithms. By way of a proof-of-concept, we apply the method to Higgs and Z boson production in association with up to two jets.Comment: 27 pages, 17 figure

Standard Model Higgs boson production in association with a top anti-top pair at NLO with parton showering

We present predictions for the production cross section of a Standard Model Higgs boson in association with a top-antitop pair at next-to-leading order accuracy using matrix elements obtained from the HELAC-Oneloop package. The NLO prediction was interfaced to the PYTHIA and HERWIG shower Monte Carlo programs with the help of POWHEG-Box, allowing for decays of massive particles, showering and hadronization, thus leading to final results at the hadron level.Comment: 14 pages, 9 figure