Source Of Particle Production Research Articles

Unruh Effect and Information Entropy Approach

The Unruh effect can be considered a source of particle production. The idea has been widely employed in order to explain multiparticle production in hadronic and heavy-ion collisions at ultrarelativistic energies. The attractive feature of the application of the Unruh effect as a possible mechanism of the multiparticle production is the thermalized spectra of newly produced particles. In the present paper, the total entropy generated by the Unruh effect is calculated within the framework of information theory. In contrast to previous studies, here the calculations are conducted for the finite time of existence of the non-inertial reference frame. In this case, only a finite number of particles are produced. The dependence on the mass of the emitted particles is taken into account. Analytic expression for the entropy of radiated boson and fermion spectra is derived. We study also its asymptotics corresponding to low- and high-acceleration limiting cases. The obtained results can be further generalized to other intrinsic degrees of freedom of the emitted particles, such as spin and electric charge.

Femtoscopy of the J/ψ-nucleon interaction

I discuss the prospects of using femtoscopy in high-energy protonproton and heavy-ion collisions to learn about the low-energy J/ψ-nucleon interaction. Femtoscopy is a technique that makes it possible to obtain spatiotemporal information on particle production sources at the femtometer scale through measurements of two-hadron momentum correlation functions. These correlation functions also provide information on low-energy hadron-hadron forces as final-state effects. In particular, such correlation functions give access to the forward scattering amplitude. One can express the forward amplitude as the product of the J/ψ chromopolarizability and the nucleon’s average chromoelectric gluon distribution, the latter being relevant to the problem of the origin of the nucleon mass. I will present the results of a recent study using the information on the J/ψ-nucleon interaction from lattice QCD simulations to compute J/ψ-nucleon correlation functions. The calculated correlation functions show clear sensitivity to the final-state interaction. I conclude discussing open issues regarding the use of the effective range expansion formula to fit experimental data for small scattering lengths and large effective range parameters.

AN EFFICIENT ANALYSIS OF DIFFERENCE EQUATIONS WITH COHERENCE FRACTION UNDER THE INFLUENCE OF BOSON INTERFEROMETRY

Boson intensity correlations were examined to explore the fluid characterization produced in the collisions at the largest colliders and were perceived to have an astonishing curtailment during the computation of three-pion quantum interferences. Such analogous suppression can be probed to investigate the characteristics of particle production sources created during the collisions of heavy nuclei at unprecedented energies. We have demonstrated and analyzed the particle emissions from radiated sources with Bose–Einstein coherence that induces three-particle interferences to investigate the peculiarity of the particle emitted fluids. We are perspicacious that the bosons resemble the pertinent aspirant of coherence, and the normalized three-particle correlations evaluate the occurrence of such conglomerate fluid phases of chaotic and coherence significantly. Moreover, we also explored and analyzed the cumulant and the normalized correlations to examine the specific features of particle emission sources during the smashing of heavy nuclei. With such particular and pioneering approach, we have observed a consequential difference in the three-particle correlations and the normalized correlator at small temperature regimes.

A new analytical approach to study chaos fraction characterization by using intensity interferometry

Multi particle intensity correlations measured to investigate the fluid debris produced during the collisions at the world largest colliders and observed a remarkable suppression in the measurement of three and four pions interferences. The analogous suppression can be analyzed to explore the chaos and coherence fractions of particle production sources in the collisions of heavy nuclei at unprecedented energies. We illustrate and explore the particles emissions from radiated sources with Bose Einstein coherence which induce multi particle interferences to probe the peculiarity of the sources as well as the distinctions about the chaos fraction in the collisions at unrivalled energies. We perspicacious that pions seem to the pertinent aspirant of coherence and chaos fractions, and the normalized chaos weight factors evaluate the existence of such hybrid phases of chaos and coherence significantly. The key point of this research is that we analyze normalized chaos weight factors to examine the chaos and coherence fractions of pions during the collisions of heavy nuclei. With such distinctive and novel approach, we observe a significant difference in the normalized chaos weight factors at small temperature and large momenta regimes.

Centrality fluctuations in heavy-ion collisions

Volume or centrality fluctuations (CF) is one of the main uncertainties for interpreting the centrality dependence of many experimental observables. The CF is constrained by centrality selection based on particle multiplicity in a reference subevent, and contributes to observables measured in another subevent. Using a Glauber-based independent source model, we study the influence of CF on several distributions of multiplicity $N$ and eccentricities $\epsilon_n$: $p(N)$, $p(\epsilon_n)$, $p(\epsilon_n,\epsilon_m)$ and $p(N,\epsilon_n)$, where the effects of CF is quantified using multi-particle cumulants of these distributions. In mid-central collisions, a general relation is established between the multiplicity fluctuation and resulting CF in the reference subevent. In ultra-central collisions, where distribution of particle production sources is strongly distorted, we find these cumulants exhibit rich sign-change patterns, due to observable-dependent non-Gaussianity in the underlying distributions. The details of sign-change pattern change with the size of the collision systems. Simultaneous comparison of these different types cumulants between model prediction and experimental data can be used to constrain the CF and particle production mechanism in heavy-ion collisions. Since the concept of centrality and CF are expected to fluctuate in the longitudinal direction within a single event, we propose to use pseudorapidity-separated subevent cumulant method to explore the nature of intra-event fluctuations of centrality and collective dynamics. The subevent method can be applied for any bulk observable that is sensitive to centrality, and has the potential to separate different mechanisms for multiplicity and flow fluctuations happening at different time scales. The forward detector upgrades at RHIC and LHC will greatly enhance such studies in the future.

Rapidity distribution of particle multiplicity in DIS at small x

Analytical study of the rapidity distribution of the final state particles in deep inelastic scattering at small x is presented. We separate and analyze three sources of particle production: fragmentation of the quark–antiquark pair that these an impact, accompanying coherent soft gluon radiation due to octet color exchange in the t-channel, and fragmentation of gluons that form parton distribution functions.Connection to Catani–Ciafaloni–Fiorani–Marchesini (CCFM) equations and the role of gluon reggeization are also discussed.

Sources and dynamics of fluorescent particles in hospitals.

Fluorescent particles can be markers of bioaerosols and are therefore relevant to nosocomial infections. To date, little research has focused on fluorescent particles in occupied indoor environments, particularly hospitals. In this study, we aimed to determine the spatial and temporal variation of fluorescent particles in two large hospitals in Brisbane, Australia (one for adults and one for children). We used an Ultraviolet Aerodynamic Particle Sizer (UVAPS) to identify fluorescent particle sources, as well as their contribution to total particle concentrations. We found that the average concentrations of both fluorescent and non-fluorescent particles were higher in the adults' hospital (0.06×106 and 1.20×106 particles/m3 , respectively) than in the children's hospital (0.03×106 and 0.33×106 particles/m3 , respectively) (P<.01). However, the proportion of fluorescent particles was higher in the children's hospital. Based on the concentration results and using activity diaries, we were able to identify sources of particle production within the two hospitals. We demonstrated that particles can be easily generated by a variety of everyday activities, which are potential sources of exposure to pathogens. Future studies to further investigate their role in nosocomial infection are warranted.

Particle production beyond the thermal model

The sources of particle production in relativistic heavy-ion collisions are investigated from RHIC to LHC energies. Whereas charged-hadron production in the fragmentation sources follows a ln( s NN / s 0 ) law, particle production in the mid-rapidity low- x gluon-gluon source exhibits a much stronger dependence ∝ ln 3 ( s NN / s 0 ), and becomes dominant between RHIC and LHC energies. The equilibration of the three sources is investigated in a relativistic diffusion model (RDM). It agrees with the thermal model only for t → ∞.

Analysis of pPb collisions at LHC energies in the relativistic diffusion model

Particle production sources in pPb collisions at LHC energies are investigated in pseudorapidity space as functions of centrality. The nonequilibrium-statistical relativistic diffusion model (RDM) with three sources is applied to the analysis of preliminary charged-hadron distributions measured by the ATLAS and ALICE collaborations in pPb collisions at 5.02 TeV. The size of the midrapidity source relative to the fragmentation sources in pPb collisions is considered as function of centrality, and incident energy. At LHC energies particle production from the mid-rapidity gluon-gluon source is larger than that from the fragmentation sources at all centralities. Conclusions regarding the statistical equilibration process are drawn.

Ultraviolet energy dependence of particle production sources in relativistic heavy-ion collisions

The energy dependence of particle production sources in relativistic heavy-ion collisions is investigated from RHIC to LHC energies. Whereas charged-hadron production in the fragmentation sources follows a ln(s_NN/s_0) law, particle production in the mid-rapidity gluon-gluon source exhibits a much stronger dependence proportional to ln^3(s_NN/s_0), and becomes dominant between RHIC and LHC energies. The production of particles with pseudorapidities beyond the beam rapidity is also discussed.

Multiplicity dependence of jet-like two-particle correlation structures in p–Pb collisions at [formula omitted

Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p–Pb collisions at a nucleon–nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7<pT,assoc<pT,trig<5.0 GeV/c is examined, to include correlations induced by jets originating from low momentum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range |η|<0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p–Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton–parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p–Pb collisions. Further, the number scales only in the intermediate multiplicity region with the number of binary nucleon–nucleon collisions estimated with a Glauber Monte-Carlo simulation.

Particle production sources at LHC energies

Particle production sources at RHIC and LHC energies are investigated in pseudorapidity space. A nonequilibrium-statistical relativistic diffusion model with three sources is applied to the analysis of charged-hadron distributions in AuAu collisions at RHIC energies, in PbPb collisions at the current LHC energy of 2.76 TeV, in pPb at 5.02 TeV, and in pp. The size of the midrapidity source relative to the fragmentation sources in heavy-ion collisions is investigated as function of incident energy. At LHC energies, the midrapidity value is mostly determined by particle production from gluon–gluon collisions.

Baryon deceleration and partonic plasma creation by strong chromofields in ultrarelativistic heavy-ion collisions

Strong chromofields generated at early stages of ultrarelativistic nuclear collisions may explain not only creation of the quark-gluon plasma but also collective deceleration of net baryons. This is demonstrated by solving classical equations of motion for baryonic slabs under the action of a time-dependent chromofield. We have studied sensitivity of the slab trajectories and their final rapidities to the initial strength and decay time of the chromofield, as well as to the back reaction of the produced plasma. By proper choice of the initial chromofield energy density we can reproduce significant baryon stopping, an average rapidity loss of about two units, observed for Au + Au collisions at RHIC. Using a Bjorken-like hydrodynamical model with the particle production source, we also study the evolution of partonic plasma produced as the result of the chromofield decay. Due to the delayed formation and expansion of plasma its maximum energy density is significantly lower than the initial energy density of the chromofield. It is shown that the fluctuations of the chromofield due to the stochastic distribution of color charges help to populate the midrapidity region in the net-baryon distribution. To fit the midrapidity data we need the chromofields with initial energy densities in the range of 30 to 60 GeV/fm3. Predictions of baryon stopping for Pb + Pb collisions at LHC energies are made.

Baryon stopping and partonic plasma production by strong chromofields

Strong chromofields developed at early stages of relativistic heavy-ion collisions give rise to the collective deceleration of net baryons from colliding nuclei. We have solved classical equations of motion for baryonic slabs under the action of a time-dependent chromofield. We have studied the sensitivity of the slab trajectories and their final rapidities to the initial strength and decay pattern of the chromofield as well as to the back-reaction of produced plasma. This mechanism can naturally explain significant baryon stopping observed at Relativistic Heavy Ion Collider corresponding to an average rapidity loss $\ensuremath{\langle}\ensuremath{\delta}y\ensuremath{\rangle}\ensuremath{\approx}2$. Using a Bjorken-like hydrodynamical model with a particle production source term, we also study the evolution of partonic plasma produced as the result of chromofield decay. Due to the delayed formation and expansion of plasma, its maximum energy density is much lower than the initial energy density of the chromofield. Predictions of baryon stopping for $\text{Pb}\phantom{\rule{4.pt}{0ex}}\text{+}\phantom{\rule{4.pt}{0ex}}\text{Pb}$ collisions at Large Hadron Collider energies were made.

Aerosol production from the surface of the Great Lakes

While much is known about marine aerosol generation, little is known about aerosol produced from breaking waves in large freshwater environments or about what implications this aerosol may have for air quality and climate. We present here evidence of significant particle production from the surface of the Great Lakes. In 2009, vertical profiles of the submicron particle size distribution were measured over Lake Michigan, where we found substantial increases in ultrafine particle concentrations with the source at or near the lake surface. The Aitken mode aerosol concentration exhibits an exponential correlation with wind speed, suggesting that breaking waves along the surface were causing the observed particle formation. A calculated dry particle size distribution based on analysis of the lake water shows reasonable agreement with our observed size spectra. This new particle production source is previously un‐studied and could significantly impact atmospheric composition in the region surrounding fresh water lakes.

From RHIC to LHC: a relativistic diffusion approach

We investigate stopping and particle production in heavy-ion collisions in a Relativistic Diffusion Model (RDM). Using three sources for particle production, the energy- and centrality dependence of rapidity distributions of net protons, and pseudorapidity distributions of charged hadrons in heavy systems at RHIC energies are precisely reproduced in the analytical model. The transport coefficients are then extrapolated from Au + Au at RHIC energies (OsNN=19.6 - 200 GeV) to Pb + Pb at LHC energies of OsNN= 5.52 TeV. Rapidity distributions for net protons, and pseudorapidity spectra for produced charged particles are obtained and discussed in a three-sources model at LHC energies.

From RHIC to LHC: A relativistic diffusion approach

Stopping and particle production in heavy-ion collisions are investigated in a Relativistic Diffusion Model (RDM). Using three sources for particle production, the energy- and centrality dependence of rapidity distributions of net protons, and pseudorapidity distributions of charged hadrons in heavy systems at RHIC energies are precisely reproduced in the analytical model. The gradual approach to local thermal equilibrium is discussed. The transport coefficients are then extrapolated from Au + Au at RHIC energies ( s N N = 19.6 − 200 GeV ) to Pb + Pb at LHC energies of s N N = 5.52 TeV . Rapidity distributions fot net protons, and pseudorapidity spectra for produced charged particles are obtained and discussed in a three-sources model at LHC energies.

Diffusion in relativistic systems

Abstract A Relativistic Diffusion Model (RDM) for high-energy heavy-ion collisions is outlined and used to investigate stopping and particle production. With three sources for particle production, the energy- and centrality dependence of rapidity distributions of net protons, and pseudorapidity distributions of charged hadrons in heavy systems at RHIC energies are precisely reproduced in the analytical model. The gradual approach to local thermal equilibrium is discussed for symmetric and asymmetric (d+Au) systems. The transport coefficients are extrapolated from Au+Au at RHIC energies ( s N N = 19.6 – 200 GeV ) to Pb+Pb at LHC energies of s N N = 5.52 TeV . Rapidity distributions for net protons, and pseudorapidity spectra for the produced charged particles are obtained and discussed in a three-sources model at LHC energies.

Hydrodynamics in 5-Dimensional Cosmological Special Relativity

The dynamics of a perfect fluid is studied in 5-dimensional special relativity, a framework which can be considered the 5-d generalization of cosmological special relativity as well as the flat specialization of 5-d brane world theory. This picture, as described in an earlier paper, directly includes a particle production mechanism. Here it is showed that the source of particle production vanishes if the fluid is isentropic. Moreover it is showed that the hydrodynamical equations can be interpreted in terms of a scale factor, giving rise to a set of equations which simulate in a sense Friedmann cosmology.

Time evolution of relativistic d + Au and Au + Au collisions

AbstractThe evolution of charged‐particle production in collisions of heavy ions at relativistic energies is investigated as function of centrality in a nonequilibrium‐statistical framework. Precise agreement with recent d + Au and Au + Au data at = 200 GeV is found in a Relativistic Diffusion Model with three sources for particle production. Only the midrapidity source comes very close to local equilibrium, whereas the analyses of the overall pseudorapidity distributions show that the systems remain far from statistical equilibrium.