| 1. |
|
|
| 2. |
- Ilten, Philip, et al.
(författare)
-
Forming molecular states with hadronic rescattering
- 2022
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 58:1
-
Tidskriftsartikel (refereegranskat)abstract
- A method for modelling the prompt production of molecular states using the hadronic rescattering framework of the general-purpose Pythia event generator is introduced. Production cross sections of possible exotic hadronic molecules via hadronic rescattering at the LHC are calculated for the χc1(3872) resonance, a possible tetraquark state, as well as three possible pentaquark states, Pc+(4312), Pc+(4440), and Pc+(4457). For the Pc+ states, the expected cross section from Λ b decays is compared to the hadronic-rescattering production. The χc1(3872) cross section is compared to the fiducial χc1(3872) cross-section measurement by LHCb and found to contribute at a level of O(1 %). Finally, the expected yields of Pc+ production from hadronic rescattering during Run 3 of LHCb are estimated. The prompt background is found to be significantly larger than the prompt Pc+ signal from hadronic rescattering.
|
|
| 3. |
- Sjöstrand, Torbjörn, et al.
(författare)
-
A framework for hadronic rescattering in pp collisions
- 2020
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:10
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, a framework for hadronic rescattering in the general-purpose Pythia event generator is introduced. The starting point is the recently presented space–time picture of the hadronization process. It is now extended with a tracing of the subsequent motion of the primary hadrons, including both subsequent scattering processes among them and decays of them. The major new component is cross-section parameterizations for a range of possible hadron–hadron combinations, applicable from threshold energies upwards. The production dynamics in these collisions has also been extended to cope with different kinds of low-energy processes. The properties of the model are studied, and some first comparisons with LHC p p data are presented. Whereas it turns out that approximately half of all final particles participated in rescatterings, the net effects in p p events are still rather limited, and only striking in a few distributions. The new code opens up for several future studies, however, such as effects in p A and AA collisions.
|
|
| 4. |
- Sjöstrand, Torbjörn, et al.
(författare)
-
Hadron interactions for arbitrary energies and species, with applications to cosmic rays
- 2022
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:1
-
Tidskriftsartikel (refereegranskat)abstract
- The Pythia event generator is used in several contexts to study hadron and lepton interactions, notably p p and p p ¯ collisions. In this article we extend the hadronic modelling to encompass the collision of a wide range of hadrons h with either a proton or a neutron, or with a simplified model of nuclear matter. To this end we model hp total and partial cross sections as a function of energy, and introduce new parton distribution functions for a wide range of hadrons, as required for a proper modelling of multiparton interactions. The potential usefulness of the framework is illustrated by a simple study of the evolution of cosmic rays in the atmosphere, and by an even simpler one of shower evolution in a solid detector material. The new code will be made available for future applications.
|
|
| 5. |
- Utheim, Marius
(författare)
-
Hadronic Interactions at High and Low Energies
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the past, development of the PYTHIA event generator has mainly concentrated on the physics of proton–proton collisions at high energies, as this is the most important case to modern high energy physics experiments. However, there are situations where more generic beam configurations are relevant. This thesis presents implementations and applications of such processes in PYTHIA. The two applications discussed in this thesis are hadronic rescattering, and hadronic cascades in media. These are developed in Papers I and Iv, while Papers II and III present physics studies of rescattering.Paper I: A framework for hadronic rescattering is implemented. This includes both the rescattering algorithm itself, as well as modelling low energy interactions. Model tests are presented for proton–proton collisions.Paper II: The effects of rescattering in heavy ion collisions are studied, using the ANGANTYR framework to simulate the collisions. Of note, results indicate that rescattering can produce a significant amount of collective flow.Paper III: This work studies rescattering as a production mechanism for exotic hadrons, specifically the $χ_{c1}(3872)$ tetraquark and the $P_c^+(4312)$, $P_c^+(4440)$ and $P_c^+(4457)$ pentaquarks.Paper IV: Modelling of high energy collisions in PYTHIA is extended to general hadron–nucleon interactions. The major parts of this extension are to define cross sections for these interactions and parton distribution functions for the hadrons involved. The paper studies the features of this model in the context of hadronic cascades in media, primarily cascades initiated by cosmic rays in the atmosphere, using a toy model.
|
|
| 6. |
- Utheim, Marius, et al.
(författare)
-
Hadronic rescattering in pA and AA collisions
- 2021
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001.
-
Tidskriftsartikel (refereegranskat)abstract
- In a recent article we presented a model for hadronic rescattering, and some results were shown for pp collisions at LHC energies. In order to extend the studies to pA and AA collisions, the Angantyr model for heavy-ion collisions is taken as the starting point. Both these models are implemented within the general-purpose Monte Carlo event generator Pythia, which makes the matching reasonably straightforward, and allows for detailed studies of the full space–time evolution. The rescattering rate is significantly higher than in pp, especially for central AA collisions, where the typical primary hadron rescatters several times. We study the impact of rescattering on a number of distributions, such as $p_\perp$ and $\eta$ spectra, and the space–time evolution of the whole collision process. Notably rescattering is shown to give a significant contribution to elliptic flow in XeXe and PbPb, and to give a nontrivial impact on charm production.
|
|
