Conveners
High Multiplicities (small system)
- Christian Bierlich (Lund University (SE))
High Multiplicities (small system)
- Christian Bierlich (Lund University (SE))
High Multiplicities (small system)
- Valentina Zaccolo (Universita e INFN Trieste (IT))
High Multiplicities (small system)
- There are no conveners in this block
Results on hadron production in high-multiplicity proton-proton (pp) and proton-lead (p--Pb) collisions at the LHC energies have revealed the presence of collective phenomena reminiscent to those observed in lead-lead (Pb--Pb) collisions. The bulk particle production in Pb--Pb collisions cannot be calculated from first principles of QCD and instead relies on thermodynamic and hydrodynamic...
We present a phenomenological study of the number of Multiple Parton Interactions (MPI) as a function of mid-rapidity charged-particle multiplicity and leading transverse momentum ($\it{p_{\rm T}^{\rm {leading}}}$) in proton-proton collisions at $\sqrt{s}$ = 13 TeV using the event generator PYTHIA 8.240. We observe important correlations between leading charged particle $\it{p_{\rm T}}$ and...
The underlying mechanisms of light flavour production are currently not well understood, although they can be described in the framework of different phenomenological models. pQCD models based on hard scatterings,
such as PYTHIA, describe light flavour production via string-breakings and rope-hadronization.
Statistical thermal models predict that the production of light flavour particles is...
Strangeness enhancement reported from the ALICE Collaboration [1] is referred to as an indication of the existence of quark-gluon plasma (QGP) in small colliding systems such as p+p and p+Pb collisions. Yield ratios of strange hadron show continuous increase as a function of multiplicity and saturation in averaged Pb+Pb events when the QGP is supposed to be formed. Motivated by this data, we...
Collectivity in small systems with the CMS experiment
Particle interferometry has proven to be an indispensable tool in probing the space-time evolution of femtoscopic collision systems. In this talk, I show how hydrodynamic predictions for the space-time evolution of high-multiplicity $pp$ and $p+$Pb collisions can be tested against interferometric observables designed to probe their size and shape. In particular, I consider how the dependence...
Measurements of distributions of two weighted angular moments derived from jet
constituents are presented. The jet-pull angle and the jet-pull magnitude, both of
which are derived from the jet-pull angular moment, encode the colour connections between
partons that seed the jets.
The measurements are performed in top-quark-antiquark events with one leptonically
decaying W boson and one...
We have developed a framework for hadronic rescattering in Pythia. Our goal is to study how rescattering can account for observed phenomena such as flow, jet quenching, etc. In this presentation I will outline our algorithm and present some preliminary results.
High multiplicity events in heavy-ion collisions are still under debate whether they produce an extremely hot and dense matter similar to the QGP formed on heavy atomic nuclei collisions. One of the main characteristics of the formation of this state is that it behaves like a near-perfect fluid, with very tiny shear viscosity. We present an estimate of the shear and bulk viscosity properties...
The hadronization of the deconfined matter arising in high-energy particle collisions is considered in terms of the first kind phase transition in the multiple flux tube approach. Based on the compactification of the standard (3+1) chromodynamics into $ QCD_{xy} + QCD_{zt}$, the rate of hadron production in particle collisions with respect to both the rapidity and $p_T$ distributions ...
Recently, an interesting faster than linear dependence of quarkonium production on charged particle multiplicity in p+p collisions has been observed. This can be used to study basic particle production mechanism and relation between soft and hard QCD processes. Such a strong increase of normalized particle yield from hard processes with respect to normalized charged particle multiplicity may...
At the LHC energies Multiple Parton Interactions (MPI) are expected to affect not only processes involving soft particle production, but also the hard momentum scales relevant for the production of heavy quarks, such as charm and beauty. Quarkonium measurements in high-multiplicity proton-proton (pp) collisions can shed light on the role of MPI at such hard momentum scales, as well as on the...
Measurements of the production of light- and heavy-flavor hadrons are of great importance for studies of the matter produced in high-energy collisions. The ALICE experiment has excellent tracking and particle identification capabilities, which have been used to measure a wide variety of hadrons as a function of multiplicity in pp collisions. Studies of light- and heavy-flavor hadrons in...
Certain data features that were attributed to quark-gluon plasma (QGP) formation in more-central A-A collisions -- evidence for radial flow and jet quenching in pt spectra, v2, v3, etc. in azimuth correlations, one or two "ridge" structures in long-range angular correlations -- have more recently been observed in high-multiplicity p-A and even p-p collisions. Arguing by analogy with A-A...
