arXiv subjects

A. Fernández Téllez

Publications and source records attributed to A. Fernández Téllez.

14 recordsLinked to original sources

arXiv2026

Internal energy of the medium formed in pp collisions

In this paper, we perform a thermostatistical analysis of the charged particles produced in minimum bias pp collisions across different energies available at the LHC-CERN reported by the ALICE Collaboration. To this end, we adopted the normalized $\pT$ spectrum as the probability density function governing the $\pT$ microstates of the produced hadrons, from which we can compute the entropy following the Shannon definition or the average $\pT$ as the Bjorken-type energy estimator. Additionally, we estimate the temperature from the slope of the $\pT$ spectrum at low $\pT$ values. We use the Hagedorn and Tricomi functions to describe the $\pT$ spectrum within a nonextensive approach and determine consistent thermodynamic frameworks by solving the fundamental relation $dE/dT=C$, where $C=TdS/dT$ is the heat capacity. We found that the internal energy behaves nonlinearly at LHC energies, indicating that the count of degrees of freedom is more complex than simply adding the number of flavors present in the hadron production. The main implication of our results is that the systems produced in pp collisions depart from the ideal gas picture and explain why the production of high $\pT$ hadrons has always been observed, even in earlier experiments, which may also encompass other experiments colliding e$^-$p or e$^+$e$^-$.

hep-ph↗

arXiv2026

Complexity drives the symmetry breaking of temperature fluctuations

Frequently, nonextensive systems are described through $q$-exponential functions, where the $q$-parameter determines how far a system is from equilibrium. In this work, we study systems constrained to $q-1\ll1$ to describe systems near thermal equilibrium, and derive the probability density function and temperature fluctuations. To this end, we derive the series expansion of the $q$-exponential function, yielding a perturbative series that is a superposition of gamma distributions. On the other hand, the temperature fluctuations are expressed as a superposition of Dirac delta functions and their derivatives, meaning that the bulk of the system remains at a constant temperature, while point-temperature variations emerge, marking the system's departure from thermal equilibrium. The statistics of the temperature fluctuations exhibit a transition from a symmetric to a nonsymmetric distribution as the nonextensive parameter increases. These results provide evidence of the association between the emergence of nonextensivity and the symmetry breaking of temperature fluctuations.

cond-mat.stat-mech↗

arXiv2025

Assessing the effectiveness of barrier allocation strategies against the propagation of phytopathogens and pests with percolation

We investigate the connectivity properties of square lattices with nearest-neighbor interactions, where some sites have a reduced coordination number, meaning that certain sites can only connect through three or two adjacent sites. This model is similar to the random placement of physical barriers in plantations aimed at decreasing connectivity between susceptible individuals, which could help prevent the spread of phytopathogens and pests. In this way, we estimate the percolation threshold as a function of the fraction of sites with a reduced coordination number ($p_d$), finding that the critical curves can be well described by a $q$-exponential function. Additionally, we establish the correlation between $p_d$ and the fraction of barriers effectively placed, which follows a power law behavior. The latter is helpful in estimating the relative costs of the barrier allocation strategies. In particular, we found that the allocations of two barriers per site model $\{ \ulcorner, \lrcorner \}$ can produce savings between 5% and 10% of the strategy cost compared to the independently random barrier allocations (joint site-bond percolation). From an agroecology perspective, adding barriers to the plantation gives farmers the opportunity to sow more vulnerable plant varieties.

stat.AP↗

arXiv2025

Multiplicity dependence of the entropy and heat capacity for pp collisions at LHC energies

We investigate the multiplicity dependence of the transverse momentum spectrum of the charged particle production in pp collisions at LHC energies. To this end, we consider the experimental data sets classified with different multiplicity estimators, defined by the ALICE Collaboration, that are analyzed within the framework of nonextensive particle production. We compute the variance, kurtosis, Shannon entropy, and heat capacity of the $p_T$ spectrum to study the hardening process as a function of the multiplicity and temperature under the different event classifiers. We found that both the Shannon entropy and the heat capacity show different responses for the triggers at the forward-backward and midrapidity regions. We emphasize that the selection of event biases may induce different responses in estimating theoretical and phenomenological observables that could lead to misleading conclusions.

hep-ex↗

arXiv2025

Scaling laws for softened hadron production at LHC energies

In this paper, we conduct a data-driven study of the production of softened hadrons and their contribution to the transverse momentum spectrum. To this end, we assume that the production of charged particles at soft and hard scales fundamentally results from the fragmentation of color strings. We analyze the $p_\text{T}$-spectrum data from pp to AA collisions at LHC energies reported by the ALICE Collaboration, finding that, in all cases, the data can be collapsed into a $p_\text{T}$-exponential trend in the range 1 GeV$<p_\text{T}<$6 GeV. With this insight, the description of the $p_\text{T}$-spectrum should contain information on the charged particle production coming from two different sources: fragmentation of color strings and collective phenomena that redistribute the transverse momentum and enhance the production of particles at intermediate $p_\text{T}$. We also found different relations between the effective temperature, multiplicity, and average $p_\text{T}$ for pp and AA collisions, indicating inherent dissimilarities between small and large colliding systems. In contrast, the contribution of the softened hadrons to the $p_\text{T}$-spectrum and average $p_\text{T}$ collapse onto scaling laws. Our results show that the physical mechanisms producing softened hadrons have similar origins for all colliding systems, revealing a stronger dependence on freeze-out parameters rather than the system size.

hep-ph↗

arXiv2024

Nonextensivity and temperature fluctuations of the Higgs boson production

We determine the temperature fluctuations associated with the Higgs boson $p_T$ spectrum through the derivation of the string tension distribution corresponding to the QCD-based Hagedorn function, frequently used to fit the transverse momentum distribution (TMD). The identified string tension fluctuations are heavy tailed, behaving similarly to the $q$-Gaussian distribution. After the convolution with the Schwinger mechanism, both approaches correctly describe the entire TMD. This approach is the onset for the nonthermal description of the particle production in ultrarelativistic pp collisions. By analyzing the data of pp collisions at $\sqrt{s} =13$ TeV, we found that the average temperature associated with the Higgs boson differential cross section is around 85 times greater than the estimated value for the charged particle TMD. Our results show that the Higgs boson production exhibits the largest deviation from the thermal description.

hep-ph↗

arXiv2024

Entropy and Heat Capacity of the transverse momentum distribution for pp collisions at RHIC and LHC energies

We investigate the transverse momentum distribution (TMD) statistics from three different theoretical approaches. In particular, we explore the framework used for string models, wherein the particle production is given by the Schwinger mechanism. The thermal distribution arises from the Gaussian fluctuations of the string tension. The hard part of the TMD can be reproduced by considering heavy tailed string tension fluctuations, for instance, the Tsallis $q$-Gaussian function, giving rise to a confluent hypergeometric function that fits the entire experimental TMD data. We also discuss the QCD-based Hagerdon function, another family of fitting functions frequently used to describe the spectrum. We analyze the experimental data of minimum bias pp collisions reported by the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) experiments (from $\sqrt{s}=0.2$ TeV to $\sqrt{s}=13$ TeV). We extracted the corresponding temperature by studying the behavior of the spectra at low transverse momentum values. For the three approaches, we compute all moments, highlighting the average, variance, and kurtosis. Finally, we compute the Shannon entropy and the heat capacity through the entropy derivative with respect to the temperature. We found that the $q$-Gaussian string tension fluctuations lead to a monotonically increasing heat capacity as a function of the center of mass energy, which is also observed for the Hagedorn fitting function. This behavior is consistent with the experimental observation that the temperature slowly rises with increments of the collision energy.

hep-ph↗

arXiv2023

Viscosity of non equilibrium hot $\&$ dense QCD drop formed at LHC

We compute the bulk, $ζ$, and shear, $η$, viscosity over entropy density, $s$, for the QCD matter formed in small collision systems at LHC. We consider a scenario of the String Percolation Model by proposing a global form of the color reduction factor that describes both the thermodynamic limit and its maximum deviation due to small-bounded effects. Our method involves estimations at vanishing baryon-chemical potential, assuming local equilibrium for string clusters in the initial state. To compute $η/s$, we employed a kinetic approach that accounts QCD states as an ideal gas of partons, while $ζ/s$ is computed by using two different approaches: a simple kinetic formula and the causal dissipative relativistic fluid dynamics formulation. Our results align with Lattice QCD computations and Bayesian methods and are consistent with holographic conjecture bounds. Furthermore, our findings support the notion of a strongly interacting medium, similar to that observed in nuclear collisions, albeit with a phase transition occurring outside the thermodynamic limit.

hep-ph↗

arXiv2023

Structure of the medium formed in heavy ion collisions

We investigate the structure of the medium formed in heavy ion collisions using three different models: the Color String Percolation Model (CSPM), the Core-Shell-Color String Percolation Model (CSCSPM), and the Color Glass Condensate (CGC) framework. We analyze the radial distribution function of the transverse representation of color flux tubes in each model to determine the medium's structure. Our results indicate that the CSPM behaves as an ideal gas, while the CSCSPM exhibits a structural phase transition from a gas-like to a liquid-like structure. Additionally, our analysis of the CGC framework suggests that it produces systems that behave like interacting gases for AuAu central collisions at RHIC energies and liquid-like structures for PbPb central collisions at LHC energies.

hep-ph↗

arXiv2022

Soft and hard scales of the transverse momentum distribution in the Color String Percolation Model

In color string models, the transverse momentum distribution (TMD) is obtained through the convolution of the Schwinger mechanism with the string tension fluctuations distribution. Considering a $q$-Gaussian distribution for these fluctuations, the TMD becomes a hypergeometric confluent function that adequately reproduces the characteristic scales at low and high $p_T$ values. In this approach, the hard scale of the TMD is a consequence of considering a heavy-tailed distribution for the string tension fluctuations whose width rises as $\sqrt{s}$, multiplicity or centrality increases. In this paper, we introduce the complete information of the TMD in the color string percolation model by means of the determination of the color suppression factor, which now also depends on the parameters of the $q$-Gaussian. To this end, we analyze the reported data on pp and AA collisions at different center of mass energies, multiplicities, and centralities. In particular, for minimum bias pp collisions, we found that the $q$-Gaussian parameters and the effective temperature are monotonically increasing functions of the center of mass energy. Similar results are found for AA collisions as a function of the centrality at fixed $\sqrt{s}$. We summarize these results in a phase diagram that indicates the $q$-Gaussian parameters region allowing the quark-gluon plasma formation.

hep-ph↗

arXiv2022

Percolation leads to finite-size effects on the transition temperature and center of mass energy required for the quark-gluon plasma formation

We investigate the finite-size effects on the transition temperature associated with the quark-gluon plasma (QGP) formation. From a percolation perspective, the onset of the QGP in high-energy collisions occurs when the spanning cluster of color strings emerges. The principal result presented here is the finite-size effects on the transition temperature expressed as a power law in terms of the nucleon number. We found that the transition temperature is higher for small systems than for large ones. It means that minimal triggering conditions events in pp collisions require about twenty times higher energies than AuAu-PbPb collisions. We also estimate the center of mass energy required for the QGP formation as a function of the nucleon number. Our results are consistent with the minimal center of mass energies at which the QGP has been observed.

hep-ph↗

arXiv2021

Mobility strategies based on percolation theory to avoid the spread of diseases: COVID-19

Human mobility is an important factor in the propagation of infectious diseases. In particular, the spatial spread of a disease is a consequence of human mobility. On the other hand, the control strategies based on mobility restrictions are generally unpopular and costly. These high social and economic costs make it very important to design global protocols where the cost is minimized and effects maximized. In this work, we calculate the percolation threshold of the spread in a network of a disease. In particular, we found the number of roads to close and regions to isolate in the Puebla State, Mexico, to avoid the global spread of COVID-19. Computational simulations taking into account the proposed strategy show a potential reduction of 94% of infections. This methodology can be used in broader and different areas to help in the design of health policies. -- La movilidad de las personas es uno de los principales factores que propician la propagación de epidemias. En particular, es el factor que genera el esparcimiento de la enfermedad en diferentes regiones. Las medidas de control epidemiológico basadas en la restricción de movilidad son generalmente poco populares y las consecuencias económicas pueden llegar a ser muy grandes. Debido a los altos costos de estas medidas, es de gran relevancia tener estrategias globales que optimicen las medidas minimizando los costos. En este trabajo, se calcula el umbral de percolación de la propagación de enfermedades en redes. De manera particular, se encuentra el número de caminos a restringir y localidades que tienen que ser aisladas para limitar la propagación global de COVID-19 en el Estado de Puebla, México. Simulaciones computacionales donde se implementan las medidas de restricción de movilidad entre los diferentes municipios, junto con las medidas de confinamiento, muestran que es posible reducir un 94% de la población afectada comparado con el caso en el que no se implementa ninguna medida. Esta metodología puede ser aplicada a distintas zonas para ayudar a las autoridades de salud en la toma de decisiones.

physics.soc-ph↗

arXiv2020

Site-bond percolation solution to preventing the propagation of \textit{Phytophthora} zoospores on plantations

We propose a strategy based on the site-bond percolation to minimize the propagation of \textit{Phytophthora} zoospores on plantations, consisting in introducing physical barriers between neighboring plants. Two clustering processes are distinguished: i) one of cells with the presence of the pathogen, detected on soil analysis; and ii) that of diseased plants, revealed from a visual inspection of the plantation. The former is well described by the standard site-bond percolation. In the latter, the percolation threshold is fitted by a Tsallis distribution when no barriers are introduced. We provide, for both cases, the formulae for the minimal barrier density to prevent the emergence of the spanning cluster. Though this work is focused on a specific pathogen, the model presented here can also be applied to prevent the spreading of other pathogens that disseminate, by other means, from one plant to the neighboring ones. Finally, the application of this strategy to three types of commercialy important Mexican chili plants is also shown.

q-bio.PE↗

arXiv2017

String percolation threshold for elliptically bounded systems

It has been shown that a hot and dense deconfined nuclear matter state produced in ultra-relativistic heavy-ion collisions, can be quantitatively described by the String Percolation phenomenological model. The model address the phase transition in terms of the two-dimensional continuum percolation theory over strings, which are schematic representations of the fundamental interactions among the partons of the colliding nuclei in the initial state. In this work, we present an extension of the critical string density results including the eccentricity dependence on the initial state geometry focus on small string number with different density profile, small deviations from the different profile densities are found. The percolation threshold shows consistency with the thermodynamic limit for the uniform density profile with a large number of strings in the case of circular boundary system. A significant dependence on the eccentricity for a small number of strings compared to high occupancy systems is exhibited, the implications may become relevant in hadron-hadron or hadron-nucleus collision systems.

cond-mat.stat-mech↗