Browsing by Author "Díaz Gutiérrez, Marco Aurelio"

Now showing 1 - 14 of 14
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    A precise determination of the strong-coupling constant from the recoil of 𝒁 bosons with the ATLAS experiment at √ 𝒔 = 8 TeV
    (2023) Aad, G.; Abbott, B.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abusleme Hoffman, Angel Christian; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Bourdarios, C. Adam; Adamczyk, L.; Adamek, L.; Addepalli, S. V.; Addison, M. J.; Adelman, J.; Adiguzel, A.; Díaz Gutiérrez, Marco Aurelio; Garay Walls, Francisca Montserrat; ATLAS Collaboration; European Organisation for Nuclear Research (CERN)
    The coupling constant of the strong force is determined from the transverse-momentum distribution of 𝑍 bosons produced in 8 TeV proton–proton collisions at the LHC and recorded by the ATLAS experiment. The 𝑍-boson cross sections are measured in the full phase space of the decay leptons using 15.3 million electron and muon pairs, in a dataset collected in 2012 and corresponding to an integrated luminosity of 20.2 fb−1. The analysis is based on predictions evaluated at third order in perturbative QCD, supplemented by the resummation of logarithmically enhanced contributions in the low transverse-momentum region of the lepton pairs. The determined value of the strong coupling at the reference scale corresponding to the 𝑍-boson mass is 𝛼s(𝑚𝑍) = 0.1183 ± 0.0009. This is the most precise experimental determination of 𝛼s(𝑚𝑍) achieved so far.
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    Anomalous Positron and Antiproton Cosmic Ray Flux in the Minimal Supersymmetric Standard Model Plus R-Parity Violation
    (2025) Ortega Gutiérrez, Gonzalo; Díaz Gutiérrez, Marco Aurelio; Pontificia Universidad Católica de Chile. Instituto de Física
    The Alpha Magnetic Spectrometer (AMS) located in the International Space Station, measured anomalous fluxes of positrons and antiprotons. The standard astronomical sources are not enough to describe the fluxes measured. We explain it with physics beyond the Standard Model: the Minimal Supersymmetric Standard Model plus R-Parity Violation. Gravitino, the graviton suṕerpartner, plays a fundamental role in our study because the different gravitino decay channels would contribute to the positron and antiproton fluxes measured by AMS. The main focus of our study is to find the best branching ratios associated with the decay channels, which adjust to AMS measurements, considering gravitino properties as its mass and lifetime.
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    Erratum to: Measurement of the W-boson mass in pp collisions at s=7TeV with the ATLAS detector
    (2018) Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adersberger, M.; Adye, T.; Blunier, Sylvain; Díaz Gutiérrez, Marco Aurelio; Ochoa-Ricoux, Juan Pedro; Viaux Maira, Nicolás
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    Lepton universality in the MSSM with trilinear R-parity violation model
    (2024) Guirriman Alvarez, Alexis Vladimir; Díaz Gutiérrez, Marco Aurelio; Pontificia Universidad Católica de Chile. Facultad de Física
    The Standard Model (SM) of particle physics, though highly successful, fails to address several fundamental questions, including the neutrino masses origin, the nature of dark matter, among others. The recent LHCb collaboration analysis measured the ratio of branching fractions RK inB+ → K+ℓ+ℓ− decay to test lepton universality, a property predicted by the SM. This observable is particularly powerful due to the cancellation of hadronic uncertainties, making it a sensitive probe for new physics. The measured value of RK is consistent with the SM prediction, suggesting nosignificant lepton universality violation. Nevertheless, given the limitations of the SM, this thesis explores a SM extension using the MSSM+λ ′TRPV model. By incorporating all possible SUSY contributions, we aim to theoretically predict the experimental RK result, providing a novel perspective on determining the parameter space that fit with the experimental measurement. The analysis is conducted within an Effective Field Theory framework across four different scenarios for Wilson Coefficients to account for the higher energy scales associated with these particles, translating their effects to the measurable energy range. The theoretical calculation is performedusing a scan in Python, while respecting other experimental constraints regarding SUSY particles. We found that the parameter space that respect the 3σ region of the LHCb collaboration measurement is |λ′| ≲ 10−2 or m˜ ≳ 8.5 TeV. Additionally, we found that our result is independent from each scenario for Wilson Coefficients. Finally, we discovered that RK has no particular bias towards any individual λ′ijk.
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    Measurement of KS0 and A^0 production in tt¯ dileptonic events in pp collisions at s=7 TeV with the ATLAS detector
    (2019) Aad, G.; Abbott, B.; Abbott, D. C.; Abdinov, O.; Abed Abud, A.; Abeling, K.; Abhayasinghe, D. K.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Achkar, B.; Adachi, S.; Adam, L.; Adam Bourdarios, C.; Adamczyk, L.; Adamek, L.; Díaz Gutiérrez, Marco Aurelio; Ochoa-Ricoux, Juan Pedro; Olivares Pino, Sebastián Andrés
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    Measurement of long-range two-particle azimuthal correlations in Z-boson tagged pp collisions at s=8 and 13 TeV
    (2020) Aaboud, M.; Aad, G.; Abbott, B.; Abbott, D. C.; Abdinov, O.; Abeloos, B.; Abhayasinghe, D. K.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adam, L.; Adam Bourdarios, C.; Adamczyk, L.; Adamek, L.; Adelman, J.; Blunier, Sylvain; Díaz Gutiérrez, Marco Aurelio; Lee, Graham Richard; Ochoa-Ricoux, Juan Pedro; Olivares Pino, Sebastián Andrés; Rivera Vergara, Juan Cristóbal
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    Measurement of τ polarisation in Z/γ∗ → ττ decays in proton–proton collisions at √s = 8 TeV with the ATLAS detector
    (2018) Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Blunier, Sylvain; Díaz Gutiérrez, Marco Aurelio; Garay Walls, Francisca; Lee, Graham Richard; Ochoa-Ricoux, Juan Pedro; Olivares Pino, Sebastián Andrés
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    Measurements of top-quark pair single- and double-differential cross-sections in the all-hadronic channel in pp collisions at s = 13 TeV using the ATLAS detector
    (2021) Aad, G.; Abbott, B.; Abbott, D. C.; Abed Abud, A.; Abeling, K.; Abhayasinghe, D. K.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Achkar, B.; Adam, L.; Adam Bourdarios, C.; Adamczyk, L.; Adamek, L.; Adelman, J.; Adersberger, M.; Díaz Gutiérrez, Marco Aurelio; Garay Walls, Francisca Montserrat; Ochoa-Ricoux, Juan Pedro; Olivares Pino, Sebastián Andrés
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    Observation of electroweak W±Z boson pair production in association with two jets in pp collisions at TeV with the ATLAS detector
    (Elsevier B.V, 2019) Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B.; Abhayasinghe, D. K.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Adamczyk, L; Adelman, J.; Bourdarios, C. Adam ; Blunier, Sylvain; Díaz Gutiérrez, Marco Aurelio; Garay Walls, Francisca Montserrat; Lee Graham, Richard; Ochoa Ricoux, Juan Pedro; Olivares Pino, Sebastián Andrés; Rivera Vergara, Juan Cristóbal; The ATLAS Collaboration
    An observation of electroweak production in association with two jets in proton–proton collisions is presented. The data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of TeV are used, corresponding to an integrated luminosity of. Events containing three identified leptons, either electrons or muons, and two jets are selected. The electroweak production of bosons in association with two jets is measured with an observed significance of 5.3 standard deviations. A fiducial cross-section for electroweak production including interference effects and for a single leptonic decay mode is measured to be. Total and differential fiducial cross-sections of the sum of electroweak and strong productions for several kinematic observables are also measured.
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    Search for anomalous production of prompt same-sign lepton pairs and pair-produced doubly charged Higgs bosons with s=8 TeV pp collisions using the ATLAS detector
    (2015) Aad, G.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Agatonovic Jovin, T.; Carquín López, Edson Leonardo; Díaz Gutiérrez, Marco Aurelio
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    Search for direct production of winos and higgsinos in events with two same-charge leptons or three leptons in pp collision data at √s = 13 TeV with the ATLAS detector
    (2023) Aad, G.; Abbott, B.; Abbott, D. C.; Abeling, K.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Abusleme Hoffman, Ángel C; Acharya, B. S.; Adam Bourdarios, C.; Adamczyk, L.; Adamek, L.; Addepalli, S. V.; Adelman, J.; Adiguzel, A.; Adorni, S.; Díaz Gutiérrez, Marco Aurelio; Garay Walls, Francisca Montserrat; The ATLAS collaboration
    Abstract: A search for supersymmetry targeting the direct production of winos and higgsinos is conducted in final states with either two leptons (e or µ) with the same electric charge, or three leptons. The analysis uses 139 fb−1 of pp collision data at √s = 13 TeV collected with the ATLAS detector during Run 2 of the Large Hadron Collider. No significant excess over the Standard Model expectation is observed. Simplified and complete models with and without R-parity conservation are considered. In topologies with intermediate states including either W h or W Z pairs, wino masses up to 525 GeV and 250 GeV are excluded, respectively, for a bino of vanishing mass. Higgsino masses smaller than 440 GeV are excluded in a natural R-parity-violating model with bilinear terms. Upper limits on the production cross section of generic events beyond the Standard Model as low as 40 ab are obtained in signal regions optimised for these models and also for an R-parity-violating scenario with baryon-number-violating higgsino decays into top quarks and jets. The analysis significantly improves sensitivity to supersymmetric models and other processes beyond the Standard Model that may contribute to the considered final states.
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    Search for magnetic monopoles and stable particles with high electric charges in √s = 13 TeV pp collisions with the ATLAS detector
    (2023) Aad, G.; Abbott, B.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adam Bourdarios, C.; Adamczyk, L.; Addepalli, S. V.; Addison, M. J.; Adelman, J.; Adiguzel, A.; Adye, T.; Díaz Gutiérrez, Marco Aurelio; Garay Walls, Francisca Montserrat; Urrejola Pereira, Pedro Salvador; The ATLAS collaboration
    Abstract: We present a search for magnetic monopoles and high-electric-charge objects using LHC Run 2 √s = 13 TeV proton-proton collisions recorded by the ATLAS detector. A total integrated luminosity of 138 fb−1 was collected by a specialized trigger. No highly ionizing particle candidate was observed. Considering the Drell-Yan and photon-fusion pair production mechanisms as benchmark models, cross-section upper limits are presented for spin-0 and spin-1/2 magnetic monopoles of magnetic charge 1gD and 2gD and for highelectric-charge objects of electric charge 20 ≤ |z| ≤ 100, for masses between 200 GeV and 4000 GeV. The search improves by approximately a factor of three the previous cross-section limits on the Drell-Yan production of magnetic monopoles and high-electric charge objects. Also, the frst ATLAS limits on the photon-fusion pair production mechanism of magnetic monopoles and high-electric-charge objects are obtained.
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    Study of a Neutrino Mass Texture Generated in Supergravity With Bilinear R-Parity Violation
    (2005) Díaz Gutiérrez, Marco Aurelio; Mora, C.; Zerwekh, A. R.
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    Underlying event studies with strange hadrons in pp collisions at s = 13 TeV with the ATLAS detector
    (2024) Aad, G.; Aakvaag, E.; Abbott, B.; Abdelhameed, S.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboelela, M.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Ackermann, A.; Bourdarios, C. Adam; Adamczyk, L.; Addepalli, S. V.; Addison, M. J.; Adelman, J.; Adiguzel, A.; Adye, T.; Díaz Gutiérrez, Marco Aurelio; Urrejola Pereira, Pedro Salvador; Garay Walls, Francisca Montserrat; ATLAS Collaboration
    Abstract Properties of the underlying-event in pp interactions are investigated primarily via the strange hadrons K S 0 , Λ and Λ ¯ , as reconstructed using the ATLAS detector at the LHC in minimum-bias pp collision data at s = 13 TeV. The hadrons are reconstructed via the identification of the displaced two-particle vertices corresponding to the decay modes , Λ → π - p and Λ ¯ → π + p ¯ . These are used in the construction of underlying-event observables in azimuthal regions computed relative to the leading charged-particle jet in the event. None of the hadronisation and underlying-event physics models considered can describe the data over the full kinematic range considered. Events with a leading charged-particle jet in the range of 10 < p T ≤ 40 GeV are studied using the number of prompt charged particles in the transverse region. The ratio N ( Λ + Λ ¯ ) / N ( K S 0 ) as a function of the number of such charged particles varies only slightly over this range. This disagrees with the expectations of some of the considered Monte Carlo models.