Detection of particles of dark matter from the spectrum of secondary particles in high-energy proton-proton collisions in a thermodynamic model

In a simple hydrodynamic model, the transverse momentum distributions are found for A hyperons formed in pp collisions at ultrarelativistic energies. The calculated spectra are compared with the experimental data obtained for various colliders in a wide range of proton collision energies, including the data from experiments at the Large Hadron Collider. An interpretation of the transverse momentum spectra of soft photons in pp collisions is proposed, taking into account the X17 boson with a mass of 17 MeV - a new particle, a possible candidate for the role of dark matter particles. A tube model is proposed on the basis of combining two-dimensional quantum chromodynamics and quantum electrodynamics. An interpretation is proposed for the detection of a 38 MeV boson in the spectra of photons emitted in the reactions of protons with carbon nuclei at an incident proton momentum of 5.5 GeV/c. The X38 boson with a mass of 38 MeV has a mass close to the boson mass obtained by us, equal to 35 MeV for an electromagnetic tube. This new particle was discovered in experiments carried out recently in Dubna for the reactionp p + C→2γ + X. To interpret the obtained experimental data on the spectra of emitted photons depending on their mass, it is proposed to use the formulas obtained for massive particles, setting the mass of a boson decaying into two photons equal to 38 MeV. It was proposed to consider bosons X17 and X38 as particles of dark matter.

The three point asymmetric cumulants in high multiplicity pp collisions

We study the influence of quantum interference and colour flow on three point correlations described by asymmetric cumulants in high multiplicity events in pp collisions. We use the model previously developed for the study of the collectivity in symmetric cumulants. We show that the resulting three point asymmetric cumulant is in qualitative agreement with the experimental data for the same parameters of the model as it was with the symmetric cumulants. Our results show that the initial state correlations must play a major role and may be even dominant in the explanation of the correlations in high multiplicity pp events.

Measurement of b-quark fragmentation properties in jets using the decay B± → J/ψK± in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

The fragmentation properties of jets containing b-hadrons are studied using charged B mesons in 139 fb−1 of pp collisions at $$ \sqrt{s} $$ s = 13 TeV, recorded with the ATLAS detector at the LHC during the period from 2015 to 2018. The B mesons are reconstructed using the decay of B± into J/ψK±, with the J/ψ decaying into a pair of muons. Jets are reconstructed using the anti-kt algorithm with radius parameter R = 0.4. The measurement determines the longitudinal and transverse momentum profiles of the reconstructed B hadrons with respect to the axes of the jets to which they are geometrically associated. These distributions are measured in intervals of the jet transverse momentum, ranging from 50 GeV to above 100 GeV. The results are corrected for detector effects and compared with several Monte Carlo predictions using different parton shower and hadronisation models. The results for the longitudinal and transverse profiles provide useful inputs to improve the description of heavy-flavour fragmentation in jets.