G. A. Vasquez
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View article: Unveiling the heavy neutrino nature at LHCb
Unveiling the heavy neutrino nature at LHCb Open
In this work, we study the lepton number violating ${B}_{c}$ meson decays via one intermediate on-shell heavy neutrino $N$. The specific studied process is ${B}_{c}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}N\ensuremath{\rightarrow}…
View article: Unveiling the Heavy Neutrino Nature at LHCb
Unveiling the Heavy Neutrino Nature at LHCb Open
In this work, we study the lepton number violating Bc meson decays via one intermediate on-shell heavy neutrino. The specific studied process is $B_{c}^{+} \to μ^{+} \ N \to μ^{+} μ^{+} τ^{-} ν$ which could allow distinguishing the nature …
View article: Measurement of the intrinsic hadronic contamination in the NA64$-e$ high-purity $e^+/e^-$ beam at CERN
Measurement of the intrinsic hadronic contamination in the NA64$-e$ high-purity $e^+/e^-$ beam at CERN Open
In this study, we present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c momentum. The analysis was performed using data collected by the NA6…
View article: High Rate Studies of the ATLAS sTGC Detector and Optimization of the Filter Circuit on the Input of the Front-End Amplifier
High Rate Studies of the ATLAS sTGC Detector and Optimization of the Filter Circuit on the Input of the Front-End Amplifier Open
The Large Hadron Collider (LHC) at CERN is expected to be upgraded to the High-Luminosity LHC (HL-LHC) by 2029 and achieve instantaneous luminosity around 5 - 7.5 $\times$ 10$^{34}$cm$^{-2}$ s$^{-1}$. This represents a more than 3-4 fold i…
View article: Search for a light muon-philic $Z^\prime$ with the NA64-$e$ experiment at CERN
Search for a light muon-philic $Z^\prime$ with the NA64-$e$ experiment at CERN Open
The extension of Standard Model made by inclusion of additional $U(1)$ gauge $L_μ-L_τ$ symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in $B$ meson decays. …
View article: Improved exclusion limit for light dark matter from $e^+e^-$ annihilation in NA64
Improved exclusion limit for light dark matter from $e^+e^-$ annihilation in NA64 Open
The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson $A^\prime$ were set by the NA64 experiment for the mass region $m_{A^\prime}\lesssim 250$ MeV, by analyzi…
View article: Search for pseudoscalar bosons decaying into $e^+e^-$ pairs
Search for pseudoscalar bosons decaying into $e^+e^-$ pairs Open
We report the results of a search for a light pseudoscalar particle $a$ that
couples to electrons and decays to $e^+e^-$ performed using the high-energy
CERN SPS H4 electron beam. If such pseudoscalar with a mass $\simeq 17$ MeV
exists, it…
View article: Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel
Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel Open
We report the results of a search for a new vector boson ($A'$) decaying into\ntwo dark matter particles $\\chi_1 \\chi_2$ of different mass. The heavier\n$\\chi_2$ particle subsequently decays to $\\chi_1$ and $A' \\to e^- e^+$. For a\nsu…
View article: Hunting down the X17 boson at the CERN SPS
Hunting down the X17 boson at the CERN SPS Open
Recently, the ATOMKI experiment has reported new evidence for the excess of $e^+ e^-$ events with a mass $\sim$17 MeV in the nuclear transitions of $^4$He, that they previously observed in measurements with $^8$Be. These observations could…
View article: Search for Axionlike and Scalar Particles with the NA64 Experiment
Search for Axionlike and Scalar Particles with the NA64 Experiment Open
We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced thro…
View article: Search for scalar and axionlike particles with the NA64 experiment
Search for scalar and axionlike particles with the NA64 experiment Open
We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced thro…
View article: Dark Matter Search in Missing Energy Events with NA64
Dark Matter Search in Missing Energy Events with NA64 Open
A search for sub-GeV dark matter production mediated by a new vector boson A^{'}, called a dark photon, is performed by the NA64 experiment in missing energy events from 100 GeV electron interactions in an active beam dump at the CERN SPS.…
View article: Physical Activity in Older Mexican Americans Living in Two Cities on the U.S.-Mexico Border
Physical Activity in Older Mexican Americans Living in Two Cities on the U.S.-Mexico Border Open
Background: There is limited information on physical activity in marginalized older populations like that on the U.S.-Mexico border. This study aims to understand physical activity engagement among older Hispanics residing in two U.S.-Mexi…
View article: Search for a Hypothetical 16.7 MeV Gauge Boson and Dark Photons in the NA64 Experiment at CERN
Search for a Hypothetical 16.7 MeV Gauge Boson and Dark Photons in the NA64 Experiment at CERN Open
We report the first results on a direct search for a new 16.7 MeV boson (X) which could explain the anomalous excess of e^{+}e^{-} pairs observed in the excited ^{8}Be^{*} nucleus decays. Because of its coupling to electrons, the X could b…
View article: Search for vector mediator of dark matter production in invisible decay mode
Search for vector mediator of dark matter production in invisible decay mode Open
A search is performed for a new sub-GeV vector boson (A′) mediated production of dark matter (χ) in the fixed-target experiment, NA64, at the CERN SPS. The A′, called dark photon, can be generated in the reaction e-Z→e-ZA′ of 100 GeV elect…
View article: Search for a new X(16.7) boson and dark photons in the NA64 experiment at CERN
Search for a new X(16.7) boson and dark photons in the NA64 experiment at CERN Open
We report the first results on a direct search for a new 16.7 MeV boson (X) which could explain the anomalous excess of e+e- pairs observed in the excited 8Be* nucleus decays. Due to its coupling to electrons, the X could be produced in th…
View article: Search for Invisible Decays of Sub-GeV Dark Photons in Missing-Energy Events at the CERN SPS
Search for Invisible Decays of Sub-GeV Dark Photons in Missing-Energy Events at the CERN SPS Open
We report on a direct search for sub-GeV dark photons (A^{'}), which might be produced in the reaction e^{-}Z→e^{-}ZA^{'} via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN …
View article: Performance of a full-size small-strip thin gap chamber prototype for the ATLAS new small wheel muon upgrade
Performance of a full-size small-strip thin gap chamber prototype for the ATLAS new small wheel muon upgrade Open
The instantaneous luminosity of the Large Hadron Collider at CERN will be increased up to a factor of five with respect to the present design value by undergoing an extensive upgrade program over the coming decade. The most important upgra…