Pp Interactions Research Articles

New constraints on the gamma-ray and high energy neutrino fluxes from the circumstellar interaction of SN 2023ixf

The recent supernova, SN 2023ixf, one of the closest observed type II SNe has revealed the presence of a dense circumstellar material (CSM). Interaction of the SN ejecta with this dense CSM might create high energy protons of PeV energies through shock acceleration. These accelerated protons then colliding with the CSM (inelastic pp collision) can produce secondaries such as high energy gamma-rays and neutrinos. However, no gamma-rays and neutrinos have been detected by Fermi-LAT and IceCube from this event. Fermi-LAT has placed an upper limit on the gamma-ray flux above 100 MeV to be 2.6 × 10-11 erg cm-2 s-1. On the other hand, IceCube's upper limit on muon neutrino flux is 7.3 × 10-2 GeV cm-2. Taking these limits into account and using the shock-CSM properties derived from multi-wavelength observations, we obtain new upper limits on the gamma-ray (10-11 erg cm-2 s-1) and neutrino (10-3 GeV cm-2) fluxes from SN 2023ixf produced via the pp interaction channel. While we found the gamma-ray flux to be consistent with Fermi-LAT's upper limit, the neutrino flux is found to be about 2 orders of magnitude smaller than the IceCube's upper limit. We further analyse the detection prospects of such secondary signals from future SN 2023 like events with upcoming detectors, CTA and IceCube-Gen2 and found to have great discovery potential, if any similar event occurs within 7 Mpc.

Neutrino production in starburst galaxies

ABSTRACT Understanding the origin of the diffuse flux of high-energy astrophysical neutrinos detected by IceCube has become a challenging issue within present High Energy Astrophysics. In this work, we present a model to explore the potential neutrino emission of starburst galaxies (SBG) by considering three different neutrino production zones that can be associated to a typical single SBG. The first zone is the starburst nucleus, where due to the high rate of supernova explosions, a significant amount of protons can be accelerated to high energies and undergo pp interactions with cold protons of the interstellar medium. The second zone we consider is the corresponding to the starburst wind, which is formed by the hot gas that emerges from the nucleus and interacts with the intergalactic medium generating shocks. Protons accelerated there can undergo pp interactions with the ambient matter. The third neutrino production zone we consider, is an external one, where we account for the possibility that protons escaping from the whole system interact with the cosmic microwave background. Finally, adding the neutrino contributions of the three zones, we calculate the diffuse neutrino flux and the diffuse photon flux by integration on the redshift range appropriate for SBG. We find that the model behaves well applied to nearby galaxies such as M82 and NGC 253. The contributions made to the diffuse neutrino flux are able to explain part of the data provided by IceCube if typical parameters are considered.

Broadband Multiwavelength Study of LHAASO-detected Active Galactic Nuclei

Recently, the Large High Altitude Air Shower Observatory (LHAASO) collaboration presented the first catalog of γ-ray sources using 508 days of LHAASO data, from 2021 March to 2022 September. This catalog contains four blazars and a possible LINER-type active galactic nucleus (AGN) counterpart. In this work, we establish averaged multiwavelength spectral energy distributions (SEDs) by combining data from the Fermi-Large Area Telescope, Swift, Zwicky Transient Facility, and Wide-field Infrared Survey Explorer (WISE) covering the same period as the LHAASO detection. In general, these five AGNs are found in low states at all wavelengths. To study the multiwavelength properties of these AGNs, several jet emission models, including the one-zone leptonic model, the one-zone leptonic and hadronuclear (pp) model, the one-zone proton-synchrotron model, and the spine-layer model, are applied to reproduce their averaged SEDs. We find that the one-zone leptonic model can reproduce most of the SEDs, except for the high-energy tail of the LHAASO spectra of Mrk 421 and Mrk 501. To improve the fitting, emission from pp interactions is favored in the framework of a one-zone model. The spine-layer model, which can be treated as a multizone scenario, can also provide good spectral fits. The influence of different extragalactic background light models on fitting a LHAASO energy spectrum is also discussed.

Multiplicity Distributions and Modified Combinants in the Multipomeron Model of pp Interaction at High Energies

The multiplicity distributions of charged particles and their combinants for pp collisions at LHC energies are studied within the Multipomeron Exchange Model (MEM) that takes into account the phenomenon of string fusion. It is shown that the use of Gaussian-type distributions for multiplicity distributions at a fixed number of pomerons allows, within the MEM framework, the reproduction of the resulting multiplicity distributions and the oscillatory behavior of combinants, found in the ALICE and CMS pp collision data at LHC energies. It is important that in the proposed approach, the parameters of these Gaussian-type distributions are not considered free, but are calculated from the two-particle correlation function of a single string.

Anti-diarrheal effect of piperine possibly through the interaction with inflammation inducing enzymes: In vivo and in silico studies

Piperine is a natural alkaloid that possesses a variety of therapeutic properties, including anti-inflammatory, antioxidant, antibacterial, and anticarcinogenic activities. The present study aims to assess the medicinal benefits of piperine as an anti-diarrheal agent in a chick model by utilizing in vivo and in silico techniques. For this, castor oil was administered orally to 2-day-old chicks to cause diarrhea. Bismuth subsalicylate (10 mg/kg), loperamide (3 mg/kg), and nifedipine (2.5 mg/kg) were used as positive controls, while the vehicle was utilized as a negative control. Two different doses (25 and 50 mg/kg b.w.) of the test sample (piperine) were administered orally, and the highest dose was tested with standards to investigate the synergistic activity of the test sample. In our findings, piperine prolonged the latent period while reducing the number of diarrheal feces in the experimental chicks during the monitoring period (4 h). At higher doses, piperine appears to reduce diarrheal secretion while increasing latency in chicks. Throughout the combined pharmacotherapy, piperine outperformed bismuth subsalicylate and nifedipine in terms of anti-diarrheal effects with loperamide. In molecular docking, piperine exhibited higher binding affinities towards different inflammatory enzymes such as cyclooxygenase 1 (−7.9 kcal/mol), cyclooxygenase 2 (−8.4 kcal/mol), nitric oxide synthases (−8.9 kcal/mol), and L-type calcium channel (−8.8 kcal/mol), indicating better interaction of PP with these proteins. In conclusion, piperine showed a potent anti-diarrheal effect in castor oil-induced diarrheal chicks by suppressing the inflammation and calcium ion influx induced by castor oil.

Strongly intensive variable in the model of high-energy pp interactions with the formation of string clusters

Strongly intensive variable in the model of high-energy pp interactions with the formation of string clusters

Geant4 FTF model description of the NA61/SHINE collaboration data on strange particle production in <i>pp</i>-interactions

The latest data by the NA61/SHINE collaboration on inclusive distributions of K*0 and ϕ meson’s, Ξ– and anti-Ξ+ hyperon’s production in pp interactions at Plab from 40 up to 158 GeV/c are considered. As it was shown before in experimental papers, Monte Carlo models – EPOS 1.99, UrQMD 3.4 and Pythia 6, cannot describe reasonably well the data. In the presented paper, the yields of the particles are analyzed within the framework of the Geant4 FTF model. A good description of the experimental data has been reached.

High-energy Neutrino Production from AGN Disk Transients Impacted by the Circum-disk Medium

Various supernovae, compact object coalescences, and tidal disruption events are widely believed to occur embedded in active galactic nucleus (AGN) accretion disks and generate detectable electromagnetic signals. We collectively refer to them as AGN disk transients. The inelastic hadronuclear (pp) interactions between shock-accelerated cosmic rays and AGN disk materials shortly after the ejecta shock breaks out of the disk can produce high-energy neutrinos. However, the expected efficiency of neutrino production would decay rapidly by adopting a pure Gaussian density atmosphere profile applicable for stable gas-dominated disks. On the other hand, AGN outflows and disk winds are commonly found around AGN accretion disks. In this paper, we show that the circum-disk medium would further consume the shock kinetic energy to more efficiently produce high-energy neutrinos, especially for ∼ TeV−PeV neutrinos that IceCube detects. Thanks to the existence of the circum-disk medium, we find that the neutrino production will be enhanced significantly and make a much higher contribution to the diffuse neutrino background. Optimistically, ∼20% of the diffuse neutrino background can be contributed by AGN disk transients.

Search for long-lived particles decaying to a pair of muons in proton-proton collisions at sqrt{s} = 13 TeV

An inclusive search for long-lived exotic particles decaying to a pair of muons is presented. The search uses data collected by the CMS experiment at the CERN LHC in proton-proton collisions at sqrt{s} = 13 TeV in 2016 and 2018 and corresponding to an integrated luminosity of 97.6 fb−1. The experimental signature is a pair of oppositely charged muons originating from a common secondary vertex spatially separated from the pp interaction point by distances ranging from several hundred μm to several meters. The results are interpreted in the frameworks of the hidden Abelian Higgs model, in which the Higgs boson decays to a pair of long-lived dark photons ZD, and of a simplified model, in which long-lived particles are produced in decays of an exotic heavy neutral scalar boson. For the hidden Abelian Higgs model with m(ZD) greater than 20 GeV and less than half the mass of the Higgs boson, they provide the best limits to date on the branching fraction of the Higgs boson to dark photons for cτ(ZD) (varying with m(ZD)) between 0.03 and ≈0.5 mm, and above ≈0.5 m. Our results also yield the best constraints on long-lived particles with masses larger than 10 GeV produced in decays of an exotic scalar boson heavier than the Higgs boson and decaying to a pair of muons.

Phase behavior and percolation in an equilibrium system of symmetrically interacting Janus disks on the triangular lattice

A Janus particle has two distinct areas on its surface. Denoting the two areas as P (patch) and N (nonpatch), when two particles come close to each other, the strength of the PP interaction is usually different from that of the NN interaction. Recently the interplay between a rotational-symmetry-breaking continuous phase transition and percolation has been explored for an equilibrium system of asymmetrically interacting (i.e., attractive PP interaction, zero NN and PN interactions) Janus disks on the triangular lattice. By Monte Carlo simulation and finite-size scaling analysis, in this work we study an equilibrium system of symmetrically interacting (i.e., attractive PP and NN interactions with the same strength, zero PN interaction) Janus disks on the same lattice. By definition, the phase diagram in the T–θ plane is symmetric for systems with patch sizes θ below and above 90°. We determine the phase diagram and compare it with that of the asymmetric system. Similar to the latter system, for 60° < θ < 90°, a rotational-symmetry-breaking continuous phase transition and an anisotropic percolation transition are found in the symmetric system, though the transition points in the two systems are quite different. Phase crossover curves are found to be different, e.g., a continuous varying crossover line extends between θ = 0° and 90° for the symmetric model; and in the range 0° < θ ≤ 30°, along the crossover lines of the two models, the trends of 1/T vs. θ are opposite in the two systems. We understand the latter by analytically solving the models with two particles in 0° < θ ≤ 30°. These results are helpful for understanding close-packed systems of Janus disks with more complex interactions.

Interpretation of particle yields in pp interactions at √S = 8.8, 12.3 and 17.3 GeV within statistical hadronization model

The statistical hadronization model ThermalFist was applied to numerous hadron yields measured in p+p collisions at √S = 8.8, 12.3 and 17.3 GeV, including recently published yields ofϕ-mesons, measured by the NA61/SHINE Collaboration. We consistently used the energy-dependent widths of Breit-Wigner mass distributions of hadronic resonances, as this approach was generally found to provide better agreement with experimental data. The well-established experimentalϕmeson yields are consequently accounted for (although neglecting this particle was found to improve the fit quality). The canonical treatment of particles with open strangeness with the grand canonical approach for non-strange particles gave a moderately reasonable agreement with the measured yields, only when the volume of strange particles was allowed to vary freely. In all the studied cases this volume is found to be greater than the canonical one.

Hadronuclear interactions in the jet of low TeV luminosity AGN: Implications for the low-state very-high-energy gamma-ray emission

In the study of radiation mechanisms of AGNs' jets, hadronuclear (pp) interactions are commonly neglected, because the number density of cold protons in the jet is considered insufficient. Very recently, our previous work proves that pp interactions in the low TeV luminosity AGNs, which have potential to generate detectable very-high-energy (VHE) emission, could be important. Based on this, the one-zone pp model is employed to study low-state quasi-simultaneous spectral energy distributions of a sample of low TeV luminosity AGNs in this work. Our modeling results show that the gamma-ray generated in pp interactions can explain the observed TeV spectra and has contribution to higher energy band that could be detected by the Large High Altitude Air Shower Observatory (LHAASO). In the sample, we suggest that M 87, Mrk 421 and Mrk 501 are the most likely objects to be detected by LHAASO in the near future. Other possible origins of VHE emission are also briefly discussed.

Fast Interaction Trigger for ALICE upgrade

We present the structure, functionalities and the first in-beam performance of the ALICE Fast Interaction Trigger (FIT). FIT comprises three detectors: FT0, FV0 and FDD, which use Cherenkov and scintillation effects to detect charged particles originating from proton–proton (pp) and heavy-ion collisions. FIT generates triggers for ALICE, monitors luminosity and background, measures collision time, and determines global collision parameters, such as forward multiplicity, centrality and event plane. FIT uses dedicated front-end electronics to measure time and charge of pulses at pp bunch crossing interval of 25 ns and pp (Pb–Pb) interaction rates of up to 1 MHz (50 kHz). FIT has been installed in ALICE, and its commissioning is ongoing. Upon exposition to pp collisions at the LHC injection energy of ECMS=450GeV FIT shows good performance in terms of the collision time resolution of 26 ps and the vertex resolution of 0.8 cm. It is important to note that the presented figures reflect the performance of non-calibrated detectors at lower-than-nominal collision energy (13–14 TeV). They are, therefore, expected to improve.

A pure hadronic model description of the observed neutrino emission from the tidal disruption event AT2019dsg

Recently, the IceCube Neutrino Observatory has detected the neutrino event IceCube-170922A from the radio-emitting tidal disruption event (TDE) named AT2019dsg, indicating to be one of the most likely sources of high-energy cosmic rays. So far, the photo-hadronic interaction is considered in the literature to interpret neutrino emission from AT2019dsg. Here, we examine whether the IceCube-170922A along with the broadband electromagnetic emission from the source can also be described by a pure hadronic emission employing the proton blazar inspired (PBI) model, which takes into account the non-relativistic protons that emerge under the charge neutrality situation of the blazar jet and thus offers sufficient target matter for pp interactions with shock-accelerated protons. Our findings show that the PBI model is able to consistently describe the IceCube observations on AT2019dsg and the broadband spectrum of the source without exceeding the observed X-ray and gamma-ray flux upper limits imposed by the XMM-Newton and Fermi-LAT telescopes.

Study of Strongly Intense Quantities and Robust Variances in Multi-Particle Production at LHC Energies

The strongly intense quantities and robust variances in processes of multi-particle production in pp and AA interactions at LHC energies was studied. The Monte Carlo and analytic modelling of these quantities in the framework of a quark-gluon string model were implies. The string fusion effects were also taken into account by implementing of a lattice (grid) in the impact parameter plane. Strongly intensive variable $\Sigma(n_F,\ n_B)$ was calculated for different energies for two values of the width of the observation rapidity windows as a function of the distance between the centres of this windows. Scaled variance $\omega_n$ and robust variance $R_n$ for different energies and for different width of the observation rapidity window was calculated by MC simulations.

Using Z Boson Events to Study Parton-Medium Interactions in Pb-Pb Collisions.

The spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson are reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 1.7 nb^{-1} and 320 pb^{-1}, respectively. Hadronic collision data with one reconstructed Z boson candidate with the transverse momentum p_{T}>30 GeV/c are analyzed. The Z boson constrains the initial energy and direction of the associated parton. In heavy ion events, azimuthal angular distributions of charged hadrons with respect to the direction of a Z boson are sensitive to modifications of the in-medium parton shower and medium response. compared to reference data from pp interactions, the results for central Pb-Pb collisions indicate a modification of the angular correlations. The measurements of the fragmentation functions and p_{T} spectra of charged particles in Z boson events, which are sensitive to medium modifications of the parton shower longitudinal structure, are also reported. Significant modifications in central Pb-Pb events compared to the pp reference data are also found for these observables.

Can the one-zone hadronuclear model explain the hard-TeV spectrum of BL Lac objects?

Context. The intrinsic TeV emission of some BL Lacs is characterized by a hard spectrum (the hard-TeV spectrum) after correcting for the extragalactic background light. The hard-TeV spectra pose a challenge to conventional one-zone models, including the leptonic model, the photohadronic model, the proton synchrotron model, and others. Aims. In this work, we aim to investigate whether or not the one-zone hadronuclear (pp) model can be used to interpret the hard-TeV spectra of BL Lacs without introducing extreme parameters. Methods. We provide analytical calculations that can be used to study whether or not there is a parameter space, and whether or not the charge neutrality condition of the jet can be satisfied when interpreting the hard-TeV spectra of BL Lacs without introducing a super-Eddington jet power. Results. We find that in a sample of hard-TeV BL Lacs previously collected, only the hard-TeV spectrum of 1ES 0229+200 can be explained by γ-rays from π0 decay produced in the pp interactions, but at the cost of setting a small radius of the radiation region than the Schwarzschild radius of the central black hole. Combining our findings with those of previous studies of other one-zone models, we suggest that the hard-TeV spectra of BL Lacs cannot be explained by a one-zone model without introducing extreme parameters, and should originate from the multiple radiation regions.

COMPARATIVE STUDY ON CHARGED AND NEUTRAL PION-NUCLEON COUPLING CONSTANTS USING YUKAWA POTENTIAL MODEL

The meson field theory based on the Yukawa model for nuclear forces is estimated using a simple relationship between the charged and neutral pion- nucleon coupling constant. This signifies that the charged coupling constant is larger compared to the value obtains for neutral pions. Therefore since np interaction is stronger than the pp interaction, we look at the value obtained for charged pion – nucleon constant which gives good agreement with one of the recent experimental values, and then the splitting between the charged and neutral pion – nucleon coupling constants is practically the same as that between charged and neutral pion mass. In this case, the mass difference between the charged and neutral pion is also calculated to assess the amount of charge dependence of the Neutron – Neutron scattering length

Hadronuclear interpretation of the possible neutrino emission from PKS B1424-418, GB6 J1040+0617 and PKS 1502+106

In addition to neutrino event IceCube-170922A which is observed to be associated with a γ-ray flare from blazar TXS 0506+056, there are also several neutrino events that may be associated with blazars. Among them, PKS B1424-418, GB6 J1040+0617 and PKS 1502+106 are low synchrotron peaked sources, which are usually believed to have the broad line region in the vicinity of the central black hole. They are considered as counterparts of IceCube event 35, IceCube-141209A and IceCube-190730A, respectively. By considering the proton-proton (pp) interactions between the dense gas clouds in the broad line region and the relativistic protons in the jet, we show that the pp model that is applied in this work can not only reproduce the multi-waveband spectral energy distribution but also suggest a considerable annual neutrino detection rate. We also discuss the emission from the photopion production and Bethe-Heitler pair production with a sub-Eddington jet power that is suggested in our model and find that it has little effect on the spectrum of total emission for all of three sources.

Collective Behavior of Secondary Particles in the Region of high Multiplicity in pp Interactions at 50 GeV/c

The latest results on the search for collective phenomena in proton interactions at the U-70 accelerator at IHEP (Protvino) are presented. This long-term experiment has been carried at the SVD-2 setup. Our study was aimed at a high multiplicity region where the series of collective phenomena is predicted. We have received an evidence of the formation of a pion (Bose-Einstein) condensate. We have observed two noticeable peaks in the angular distribution of charged pions interpreted as Cherenkov radiation of gluons by quarks and others phenomena.