Search results for "Droni"
showing 10 items of 596 documents
On the strength of the U A (1) anomaly at the chiral phase transition in N f = 2 QCD
2016
We study the thermal transition of QCD with two degenerate light flavours by lattice simulations using $O(a)$-improved Wilson quarks. Temperature scans are performed at a fixed value of $N_t = (aT)^{-1}=16$, where $a$ is the lattice spacing and $T$ the temperature, at three fixed zero-temperature pion masses between 200 MeV and 540 MeV. In this range we find that the transition is consistent with a broad crossover. As a probe of the restoration of chiral symmetry, we study the static screening spectrum. We observe a degeneracy between the transverse isovector vector and axial-vector channels starting from the transition temperature. Particularly striking is the strong reduction of the split…
QCD Challenges from pp to A-A Collisions
2020
This paper is a write-up of the ideas that were presented, developed and discussed at the third International Workshop on QCD Challenges from pp to A-A, which took place in August 2019 in Lund, Sweden. The goal of the workshop was to focus on some of the open questions in the field and try to come up with concrete suggestions for how to make progress on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results.
Power Corrections to Event Shapes with Mass-Dependent Operators
2013
We introduce an operator depending on the "transverse velocity'' r that describes the effect of hadron masses on the leading 1/Q power correction to event-shape observables. Here, Q is the scale of the hard collision. This work builds on earlier studies of mass effects by Salam and Wicke [J. High Energy Phys. 05 (2001) 061] and of operators by Lee and Sterman [Phys. Rev. D 75, 014022 (2007)]. Despite the fact that different event shapes have different hadron mass dependence, we provide a simple method to identify universality classes of event shapes whose power corrections depend on a common nonperturbative parameter. We also develop an operator basis to show that at a fixed value of Q, the…
A study of intermittency in Hadronic Z$^0$ Decays
1990
The correlations in rapidity in hadron production from e+e- annihilation near the Z0 resonance were studied by means of the method of factorial moments, using data taken with the DELPHI detector at LEP. The parton shower hadronization model was found to be in quantitative agreement with the data, in contrast with previous results at lower energies. © 1990.
Fragmentation in the ϕ3 theory and the LPHD hypothesis
2015
We present analytic solution of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equation at leading order (LO) in the phi^3 theory in 6 space-time dimensions. If the phi^3 model was the theory of strong interactions, the obtained solution would describe the distribution of partons in a jet. We point out that the local parton-hadron duality (LPHD) conjecture does not work in this hypothetical situation. That is, treatment of hadronisation of shower partons is essential for the description of hadron distributions in jets stemming from proton-proton (pp) collisions at \sqrt{s} = 7 TeV and from electron-positron (e+e-) annihilations at various collision energies. We use a statistical mod…
Scalar particle contribution to Higgs production via gluon fusion at NLO
2007
22 pages, 5 figures.-- ISI Article Identifier: 000252243700095.-- ArXiv pre-print available at: http://arxiv.org/abs/0709.4227
Global analysis of fragmentation functions for eta mesons
2011
Fragmentation functions for eta mesons are extracted at next-to-leading order accuracy of QCD in a global analysis of data taken in electron-positron annihilation and proton-proton scattering experiments. The obtained parametrization is in good agreement with all data sets analyzed and can be utilized, for instance, in future studies of double-spin asymmetries for single-inclusive eta production. The Lagrange multiplier technique is used to estimate the uncertainties of the fragmentation functions and to assess the role of the different data sets in constraining them.
Study of the f(2)(1270) , f(2)'(1525) , f(0)(1370) and f(0)(1710) in the J/psi radiative decays
2009
In this paper we present an approach to study the radiative decay modes of the J/psi into a photon and one of the tensor mesons f (2)(1270) , f' (2)(1525) , as well as the scalar ones f (0)(1370) and f (0)(1710) . Especially, we compare predictions that emerge from a scheme where the states appear dynamically in the solution of vector meson-vector meson scattering amplitudes to those from a (admittedly naive) quark model. We provide evidence that it might be possible to distinguish amongst the two scenarios, once improved data are available.
Measuring the top energy asymmetry at the LHC: QCD and SMEFT interpretations
2020
The energy asymmetry in top-antitop-jet production is an observable of the top charge asymmetry designed for the LHC. We perform a realistic analysis in the boosted kinematic regime, including effects of the parton shower, hadronization and expected experimental uncertainties. Our predictions at particle level show that the energy asymmetry in the Standard Model can be measured with a significance of $3\sigma$ during Run 3, and with more than $5\sigma$ significance at the HL-LHC. Beyond the Standard Model the energy asymmetry is a sensitive probe of new physics with couplings to top quarks. In the framework of the Standard Model Effective Field Theory, we show that the sensitivity of the en…
Jet transverse fragmentation momentum from h–h correlations in pp and p–Pb collisions
2016
QCD color coherence phenomena, like angular ordering, can be studied by looking at jet fragmentation. As the jet is fragmenting, it is expected to go through two different phases. First, there is QCD branching that is calculable in perturbative QCD. Next, the produced partons hadronize in a non-perturbative way later in a hadronization process. The jet fragmentation can be studied using the method of two particle correlations. A useful observable is the jet transverse fragmentation momentum $j_{\mathrm{T}}$, which describes the angular width of the jet. In this contribution, a differential study will be presented in which separate $j_{\mathrm{T}}$ components for branching and hadronization …