Reaction Pp Research Articles

Insights into the inhibitory effects of trichloroisocyanuric acid disinfectant on the phototransformation of polypropylene microplastics

The chemical components in the natural aquatic environment have the potential to be involved in phototransformation of microplastics (MPs). Little information is available regarding the mediation effects of artificially introduced chemicals on MP phototransformation, especially those used in aquaculture water that are vulnerable to human interference. Herein, this study investigated the phototransformation process and mechanism of polypropylene microplastic (PP MPs) in presence of trichloroisocyanuric acid (TCCA) disinfectant with unique properties unlike the conventional inorganic chlorine disinfectants. The results showed that the presence of TCCA inhibited the surface photooxidation of PP MPs. Analysis of PP MP surface and reaction filtrate indicated that the inhibitory effects were likely derived from TCCA derivatives and the weakening in promoting effect of polypropylene microplastic-derived dissolved organic matter (PP-DOM) as photolytic byproducts, with the more important role of free chlorine in initial period and that of other chlorine species (i.e., the adsorbed chloride ions (Cl−), newly formed carbon-chlorine (CCl) bonds, chlorinated cyanurates, and chlorinated products) in middle and later period. The study highlights for the first time the important role of chlorine species derived from TCCA in phototransformation process of co-existed PP MPs and proposes a previously unrecognized phototransformation pathway, which will provide a new understanding and knowledge for the environmental behavior of MPs in aquaculture environment.

Hyperon production and interaction studies in protonproton scattering with HADES

Hyperons and their interactions with baryonic matter may play a key role in our understanding of the core of neutron stars. Moreover, the internal structure of hyperons and their excitations are of great interest. Their structure can be probed by exploiting their couplings to radiative probes such as by measuring electromagnetic transition form factors. HADES (High-Acceptance Di-Electron Spectrometer) at GSI collected high-statistics proton-proton scattering data in 2022 at √s = 3.48 GeV. The Λ - Λ interaction is currently being studied in this data along with production of Σ states where the Dalitz decay of hyperons might be observed for the first time. In addition, the reaction pp → pK+K+Ξ−[π−Λ[pπ−]] has been studied to probe the production mechanism of double strangeness near its production threshold. This proceeding addresses the hyperon physics case and discusses the ongoing Ξ− analysis. A preliminary upper limit for the cross section at √s = 3.48 GeV is presented taking into account only statistical uncertainties.

Analysis procedures in deriving of the differential cross section of the reaction pp ! {pp}sp0 at energies 1.6–2.4 GeV

The reaction pp → {pp} s p 0 , where {pp}s denotes a diproton, i.e. an unbound interacting proton pair in the 1 S 0 , state, was investigated in order to obtain a differential cross section ds/dW at small angles in the energy range 1.6–2.4 GeV. This work is intended for the presentation of the main procedures in the processing of experimental data.

Pp scattering at the LHC with the lepton pair production and one proton tagging

Analytical formulas for the cross section of the reaction pp rightarrow p + ell ^+ ell ^- + X are presented. Fiducial cross sections are compared with those measured recently by the ATLAS collaboration.

First Measurement of the Z→μ^{+}μ^{-} Angular Coefficients in the Forward Region of pp Collisions at sqrt[s]=13 TeV.

The first study of the angular distribution of μ^{+}μ^{-} pairs produced in the forward rapidity region via the Drell-Yan reaction pp→γ^{*}/Z+X→ℓ^{+}ℓ^{-}+X is presented, using data collected with the LHCb detector at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.1 fb^{-1}. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the Z-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton.

The two-step mechanism explaning the dibaryon “d ∗ (2380)” peak

In this talk we show that the two-step sequential one pion production mechanism, np(I = 0) → π −pp, followed by the fusion reaction pp → π +d, can explain the narrow peak identified with a “d ∗ (2380)” dibaryon in the np → π +π −d reaction with π +π − in I = 0. We demonstrate that the second step pp → π +d is driven by a triangle singularity that determines the position of the peak of the reaction and the large strength of the cross section. The combined cross section of these two mechanisms produce a narrow peak with the position, width and strength compatible with the experimental observation within the approximations done. This novel interpretation of the peak without invoking a dibaryon explains why the peak is not observed in other reactions where it has been searched for.

Investigation of the Σ0 hyperon production in p(3.5GeV)+p collisions

The production mechanism of the Σ0 was investigated via the exclusive reaction pp → pK+Σ0 at a beam energy 3.5 GeV with the HADES detector. The preliminary value of the extracted total production cross section is found to be σ(pK+Σ0)[μb] = 17.7 ± 1.7(stat) ± 1.6(syst). The dynamics of the reaction pp → pK+Σ0 was investigated by studying the angular distributions in the center-of-mass, Gottfried-Jackson and helicity frames. The angular distributions in the center-of-mass frame supports the pion exchange mechanism. Furthermore, the helicity angular distributions are highly non-isotropic, which is a clear indication of resonant production component.

Unfolding the effects of final-state interactions and quantum statistics in two-particle angular correlations

Angular correlations of identified particles measured in ultrarelativistic proton-proton (pp) and heavy-ion collisions exhibit a number of features which depend on the collision system and particle type under consideration. Those features are produced by mechanisms, such as (mini)jets, elliptic flow, resonance decays, and conservation laws. In addition, of particular importance are those related to the quantum statistics (QS) and final-state interactions (FSIs). In this paper we show how to unfold the QS and FSI contributions in angular correlation functions by employing a Monte Carlo approach and using momentum correlations (femtoscopy), focusing on pp reactions. We validate the proposed method with PYTHIA 8 Monte Carlo simulations of pp collisions at $\sqrt{s}=13$ TeV coupled to calculations of QS and FSI effects with the Lednick\'y and Lyuboshitz formalism and provide predictions for the unfolded effects. In particular, we show how those effects modify the shape of the angular correlation function with emphasis on pions and protons. Most importantly, specific structures observed in the near-side region for both baryon-baryon and baryon-antibaryon pairs, originating from the strong interaction, are unveiled with the proposed method.

Highly Tough and Thermally Stable Polylactide Blends Compatibilized with Glycidyl Methacrylate‐Grafted Polypropylene

AbstractTo attain eco‐friendly and sustainable polylactide (PLA) materials possessing highly enhanced toughness, thermal stability, and processability without significant loss in elastic modulus, for the first time, PLA‐dominant blends with 1–30 wt% glycidyl methacrylate‐grafted polypropylene (PPGMA) loadings are fabricated via an efficient masterbatch melt‐compounding process. For the purpose, PPGMA is fabricated via in situ grafting reaction of PP with GMA and styrene. The scanning electron microscope images reveal that PLA/PPGMA blends do not show recognizable phase‐separated domains, unlike immiscible PLA/PP blends. The Fourier‐transform infrared spectroscopic and melt‐rheological analyses support the presence of specific interactions between PLA and PPGMA as well as the compatibilizing effect of PPGMA‐g‐PLA formed during the melt‐compounding. The thermal analyses demonstrate that PPGMA component accelerates the crystallization of PLA in the blends and that the thermal decomposition temperatures of PLA/PPGMA blends are higher than those of neat PLA and PPGMA components. The dynamic mechanical analysis shows that a maximum storage modulus is attained for PLA‐dominant blend with 30 wt% PPGMA. Noticeably, the impact strength (≈305.6 J m−1) of PLA‐dominant blend with only 5 wt% PPGMA loading is almost three times higher than that (≈111.6 J m−1) of neat PLA and it is very comparable to the value (≈316.9 J m−1) of neat PP.

Studies of hyperon production in HADES at FAIR-Phase0 — the case of an inclusive Σ(1385)+ measurement in pp reaction

In this proceedings first results of an inclusive measurement of the Σ(1385) + resonance produced in the proton-proton reaction at the beam kinetic energy of 3.5 GeV are presented. Mass of the Σ(1385)+ resonance extracted from a fit with the Breit-Wigner function is found to be M0 = 1380.02 MeV with a fixed width of Γ = 40MeV resulting from the previous exclusive measurements done by HADES. The presented analysis is a first trial to obtain the inclusive cross section for the production of the first-excited state of the Σ hyperon in elementary collisions at SIS energy range. The inclusive cross section is important for studies of the hyperon electromagnetic decays, which are one of the main fields of interest of the HADES experimental program during the FAIR-Phase0.

Measurement of the central exclusive production of charged particle pairs in proton-proton collisions at sqrt{s} = 200 GeV with the STAR detector at RHIC

We report on the measurement of the Central Exclusive Production of charged particle pairs h+h− (h = π, K, p) with the STAR detector at RHIC in proton-proton collisions at sqrt{s} = 200 GeV. The charged particle pairs produced in the reaction pp → p′ + h+h− + p′ are reconstructed from the tracks in the central detector and identified using the specific energy loss and the time of flight method, while the forward-scattered protons are measured in the Roman Pot system. Exclusivity of the event is guaranteed by requiring the transverse momentum balance of all four final-state particles. Differential cross sections are measured as functions of observables related to the central hadronic final state and to the forward-scattered protons. They are measured in a fiducial region corresponding to the acceptance of the STAR detector and determined by the central particles’ transverse momenta and pseudorapidities as well as by the forward-scattered protons’ momenta. This fiducial region roughly corresponds to the square of the four-momentum transfers at the proton vertices in the range 0.04 GeV2< −t1, −t2< 0.2 GeV2, invariant masses of the charged particle pairs up to a few GeV and pseudorapidities of the centrally-produced hadrons in the range |η| < 0.7. The measured cross sections are compared to phenomenological predictions based on the Double Pomeron Exchange (DPE) model. Structures observed in the mass spectra of π+π− and K+K− pairs are consistent with the DPE model, while angular distributions of pions suggest a dominant spin-0 contribution to π+π− production. For π+π− production, the fiducial cross section is extrapolated to the Lorentz-invariant region, which allows decomposition of the invariant mass spectrum into continuum and resonant contributions. The extrapolated cross section is well described by the continuum production and at least three resonances, the f0(980), f2(1270) and f0(1500), with a possible small contribution from the f0(1370). Fits to the extrapolated differential cross section as a function of t1 and t2 enable extraction of the exponential slope parameters in several bins of the invariant mass of π+π− pairs. These parameters are sensitive to the size of the interaction region.

Solid‐state grafting of maleic anhydride onto polypropylene: The influence of morphology of polypropylene on heterogeneous reaction

AbstractPolypropylene (PP) was modified with maleic anhydride (MAH) via heterogeneous solid‐state radical grafting performed in a fluidized polymerization reactor. The effect of PP morphology and different concentration of initiator (dibenzoyl peroxide, DBP) on the course of the reaction and grafting efficiency was evaluated with using infrared spectroscopy, scanning electron microscopy (SEM) and particle surface analysis (BET method). With respect to obtained results, the reaction course can be strongly affected by the reaction conditions and PP morphology. Unlike the reactive modification in melt, heterogeneous reaction exhibits lower extent of β‐scission albeit the reaction conversion is lower. Solid‐state grafting can be used as an alternative method for the surface modification of nonpolar surfaces with polar monomers under mild conditions.

Study of pp → 𝚵+ ΛK- with the PANDA Detector

For a deeper insight into the mechanisms of non-perturbative QCD it is essential to understand the excitation pattern of baryons. Up to now only the nucleon excitation spectrum has been subject to systematic experimental studies, while very little is known on excited states of double or triple strange baryons. In studies of antiproton-proton collisions the PANDA experiment is well-suited for a comprehensive baryon spectroscopy program in the multi-strange sector. A large fraction of the inelastic pp cross section is associated to final states with a baryon-antibaryon pair together with additional mesons, giving access to excited states both in the baryon and the antibaryon channel. For final states containing a 𝚵+ 𝚵- pair, cross sections up to µb are expected, corresponding to production rates of ~ 106/d at a luminosity L = 1031 cm-2 s-1. This study focuses on excited 𝚵- states decaying into ΛK-. A strategy to reconstruct the reaction pp → 𝚵+ 𝚵* and its charge conjugate channel with the PANDA detector will be presented.

Atomic effects in astrophysical nuclear fusion reactions

The electron-screening acceleration of laboratory fusion reactions at astrophysical' energies is an unsolved problem of great importance to astrophysics. That effect is modeled here by considering the fusion of hydrogen-like atoms whose electron probability density is used in Poisson 's equation in order to derive the corresponding screened Coulomb potential energy. That way atomic excitations and deformations of the fusing atoms can be taken into account. Those potentials are then treated semiclassically in order to obtain the screening (accelerating) factor of the reaction. By means of the proposed model the effect of a superstrong magnetic field on laboratory Hydrogen fusion reactions is investigated here for the first time showing that, despite the considerable increase in the cross section of the dd reaction, the pp reaction is still too slow to justify experimentation. The proposed model is finally applied on the H2 (d, p) H3 fusion reaction describing satisfactorily the experimental data although some ambiguity remains regarding the molecular nature of the deuteron target. Notably, the present method gives a sufficiently high screening energy for Hydrogen fusion reactions so that the take-away energy of the spectator nucleus can also be taken into account.

Study of baryonic resonances and ρ meson production in the reaction pp → ppπ+π− at 3.5 GeV with HADES

We report on measurements of baryon resonance and ρ meson production in the exclusive pp → ppπ+π− channel at a beam kinetic energy of 3.5 GeV measured with the HADES experimental setup. The differential distributions are compared to Monte Carlo simulations based on a resonance model assuming an incoherent sum of contributions of various baryonic resonances with masses below 2 GeV and using inputs from one pion production measured in the same experiment. A very good description of the two pion production is achieved allowing for an estimate of the contribution of one and double baryon-resonance excitation. Using appropriate kinematical cuts the ρ meson signal could also be extracted.

Δ-Isobar contribution to the pion production in the reaction pp → {pp}sπ0

ANKE@COSY data on the cross section of the reaction pp → {pp}sπ0, where {pp}s is the proton pair in the 1S 0 state at small excitation energy Epp = 0 – 3 MeV, obtained at beam energies 0.5 - 2.0 GeV are analyzed within the one-pion exchange model. The model involves the subprocess π0 p → π0 p and accounts for the final state pp-interaction. A broad maximum observed in the cross section of the reaction pp → {pp}sπ0 at 0.5 - 1.4 GeV in the forward direction is explained by this model as a dominant contribution of the isospin $\cfrac{3}{2}$ in the π0 p-scattering. The second bump in data at 2 GeV is underpredicted within this model by one order of magnitude. An explicit excitation of the Δ(1232)-isobar using the box-diagram is also considered in the region of the first maximum.

Resonance behaviour of the reactions pp → {pp}sπ0 and pd → pdππ in the 1-2 GeV region

Resonance peaks observed in the cross sections of the reaction pp → {pp}sπ0, where {pp}s is the 1S0 state of the proton pair, and pd → pdππ in the GeV region are considered in the framework of mechanisms involving known baryon and two-baryon resonances.

Non-strange dibaryons studied in the γd → π0π0d reaction

Coherent double neutral-pion photoproduction on the deuteron, γd→π0π0d, has been experimentally studied at incident photon energies ranging from 0.75 to 1.15 GeV. The total cross section as a function of the γd center-of-mass energy shows resonance-like behavior, which peaks at approximately 2.47 and 2.63 GeV. The measured angular distribution of deuteron emission is rather flat, which cannot be reproduced by the kinematics of quasi-free π0π0 production with deuteron coalescence. In π0d invariant-mass distributions, a clear peak is observed at 2.14±0.01 GeV/c2 with a width of 0.09±0.01 GeV/c2. The spin-parity of this state is restricted to 1+, 2+ or 3− from the angular distributions of the two π0s. The present work shows strong evidence for the existence of an isovector dibaryon resonance with a mass of 2.14 GeV/c2. The 2+ assignment is consistent with the theoretically predicted D12 state, and also with the energy dependence of the πd partial-wave amplitude P23 for the π±d→π±d and π+d→pp reactions.

Time-Like Baryon Transitions in Hadroproduction

The Dalitz decay of baryonic resonances (B $$\rightarrow $$ N $$e^+e^-$$ ) gives access to the time-like electromagnetic structure of baryonic transitions at small positive values of the squared four momentum transferred. Such processes were investigated by the HADES collaboration in elementary hadronic interactions. The Dalitz decay branching ratio of the $$\varDelta (1232)$$ resonance has been measured for the first time in pp reactions at 1.25 GeV beam energy. At higher energies, the $$e^+e^-$$ emission from baryonic decays is shown to be sensitive to transition form factors of the Vector Dominance Model type. Using a pion beam, Dalitz decays of baryonic resonances can be measured more directly. In addition, the simultaneous measurement of hadronic channels provides a new data base for baryon spectroscopy issues. Preliminary results of a test experiment in the N(1520) region are shown, together with prospects for higher resonance studies. A project of measuring hyperon Dalitz decays at GSI and later on at FAIR is also discussed. The study of Dalitz decays of baryon resonances and, in particular, the role of the $$\rho $$ meson brings useful constraints for the study of medium effects also investigated by the HADES collaboration in reactions with nuclei.

Spin Dependence of η Meson Production in Proton-Proton Collisions Close to Threshold.

Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high polarization degree of the proton beam of COSY, the reaction p[over →]p→ppη has been measured close to threshold to explore the analyzing power A_{y}. The angular distribution of A_{y} is determined with the precision improved by more than 1 order of magnitude with respect to previous results, allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q=15 MeV, signaling s-wave production with no evidence for higher partial waves. At Q=72 MeV the data reveal strong interference of Ps and Pp partial waves and cancellation of (Pp)^{2} and Ss^{*}Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the η meson.