arXiv subjects

C. Ayerbe Gayoso

Publications and source records attributed to C. Ayerbe Gayoso.

At least 55 records · Page 3Linked to original sources

arXiv2022

ECCE unpolarized TMD measurements

We performed feasibility studies for various measurements that are related to unpolarized TMD distribution and fragmentation functions. The processes studied include semi-inclusive Deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The single hadron cross sections and multiplicities were extracted as a function of the DIS variables $x$ and $Q^2$, as well as the semi-inclusive variables $z$, which corresponds to the momentum fraction the detected hadron carries relative to the struck parton and $P_T$, which corresponds to the transverse momentum of the detected hadron relative to the virtual photon. The expected statistical precision of such measurements is extrapolated to accumulated luminosities of 10 fb$^{-1}$ and potential systematic uncertainties are approximated given the deviations between true and reconstructed yields.

hep-ex↗

arXiv2022

Exclusive J/$ψ$ Detection and Physics with ECCE

Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the spatial distribution of gluons in the nucleus. Recently the problem of the origin of hadron mass has received lots of attention in determining the anomaly contribution $M_{a}$. The trace anomaly is sensitive to the gluon condensate, and exclusive production of quarkonia such as J/$ψ$ and $Υ$ can serve as a sensitive probe to constrain it. In this paper, we present the performance of the ECCE detector for exclusive J/$ψ$ detection and the capability of this process to investigate the above physics opportunities with ECCE.

nucl-ex↗

arXiv2022

Search for $e\toτ$ Charged Lepton Flavor Violation at the EIC with the ECCE Detector

The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow μ$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to τ$ CLFV transition, potentially to be explored by the EIC. With the latest detector design of ECCE (EIC Comprehensive Chromodynamics Experiment) and projected integral luminosity of the EIC, we find the $τ$-leptons created in the DIS process $ep\to τX$ are expected to be identified with high efficiency. A first ECCE simulation study, restricted to the 3-prong $τ$-decay mode and with limited statistics for the Standard Model backgrounds, estimates that the EIC will be able to improve the current exclusion limit on $e\to τ$ CLFV by an order of magnitude.

hep-ph↗

arXiv2022

Design and Simulated Performance of Calorimetry Systems for the ECCE Detector at the Electron Ion Collider

We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range from -3.7 to 3.8 and two hadronic calorimeters. Key calorimeter performances which include energy and position resolutions, reconstruction efficiency, and particle identification will be presented.

physics.ins-det↗

arXiv2022

Precision Determination of the Neutral Weak Form Factor of $^{48}$Ca

We report a precise measurement of the parity-violating asymmetry $A_{\rm PV}$ in the elastic scattering of longitudinally polarized electrons from $^{48}{\rm Ca}$. We measure $A_{\rm PV} =2668\pm 106\ {\rm (stat)}\pm 40\ {\rm (syst)}$ parts per billion, leading to an extraction of the neutral weak form factor $F_{\rm W} (q=0.8733$ fm$^{-1}) = 0.1304 \pm 0.0052 \ {\rm (stat)}\pm 0.0020\ {\rm (syst)}$ and the charge minus the weak form factor $F_{\rm ch} - F_{\rm W} = 0.0277\pm 0.0055$. The resulting neutron skin thickness $R_n-R_p=0.121 \pm 0.026\ {\rm (exp)} \pm 0.024\ {\rm (model)}$~fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear matter.

nucl-ex↗

arXiv2022

AI-assisted Optimization of the ECCE Tracking System at the Electron Ion Collider

The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to leverage Artificial Intelligence (AI) already starting from the design and R&D phases. The EIC Comprehensive Chromodynamics Experiment (ECCE) is a consortium that proposed a detector design based on a 1.5T solenoid. The EIC detector proposal review concluded that the ECCE design will serve as the reference design for an EIC detector. Herein we describe a comprehensive optimization of the ECCE tracker using AI. The work required a complex parametrization of the simulated detector system. Our approach dealt with an optimization problem in a multidimensional design space driven by multiple objectives that encode the detector performance, while satisfying several mechanical constraints. We describe our strategy and show results obtained for the ECCE tracking system. The AI-assisted design is agnostic to the simulation framework and can be extended to other sub-detectors or to a system of sub-detectors to further optimize the performance of the EIC detector.

physics.ins-det↗

arXiv2022

Scientific Computing Plan for the ECCE Detector at the Electron Ion Collider

The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing these challenges in the process of producing a complete detector proposal based upon detailed detector and physics simulations. In this document, the software and computing efforts to produce this proposal are discussed; furthermore, the computing and software model and resources required for the future of ECCE are described.

physics.ins-det↗

arXiv2022

Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q$^2$) up to 15.75~\gevsq. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q$^2$ and double the range over which a longitudinal/transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q$^2$ and attributed to hard two-photon exchange (TPE) effects, extending to 8~(GeV/c)$^2$ the range of Q$^2$ for which a discrepancy is established at $>$95\% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q$^2$.

nucl-ex↗

arXiv2022

Progress and Opportunities in Backward angle (u-channel) Physics

Backward angle (u-channel) scattering provides complementary information for studies of hadron spectroscopy and structure, but has been less comprehensively studied than the corresponding forward angle case. As a result, the physics of u-channel scattering poses a range of new experimental and theoretical opportunities and questions. We summarize recent progress in measuring and understanding high energy reactions with baryon charge exchange in the u-channel, as discussed in the first backward angle (u-channel) Physics Workshop. In particular, we discuss backward angle measurements and their theoretical description via both hadronic models and the collinear factorization approach, and discuss planned future measurements of u-channel physics. Finally, we propose outstanding questions and challenges for u-channel physics.

hep-ph↗

arXiv2022

Beam-Recoil Transferred Polarization in $K^+Y$ Electroproduction in the Nucleon Resonance Region with CLAS12

Beam-recoil transferred polarizations for the exclusive electroproduction of $K^+Λ$ and $K^+Σ^0$ final states from an unpolarized proton target have been measured using the CLAS12 spectrometer at Jefferson Laboratory. The measurements at beam energies of 6.535~GeV and 7.546~GeV span the range of four-momentum transfer $Q^2$ from 0.3 to 4.5~GeV$^2$ and invariant energy $W$ from 1.6 to 2.4~GeV, while covering the full center-of-mass angular range of the $K^+$. These new data extend the existing hyperon polarization data from CLAS in a similar kinematic range but from a significantly larger dataset. They represent an important addition to the world data, allowing for better exploration of the reaction mechanism in strangeness production processes, for further understanding of the spectrum and structure of excited nucleon states, and for improved insight into the strong interaction in the regime of non-perturbative dynamics.

nucl-ex↗

arXiv2022

The cross-section measurement for the $^3{\textrm H}(e,e'K^+)nnΛ$ reaction

The small binding energy of the hypertrition leads to predictions of non-existence of bound hypernuclei for isotriplet three-body systems such as $nnΛ$. However, invariant mass spectroscopy at GSI has reported events that may be interpreted as the bound $nnΛ$ state. The $nnΛ$ state was sought by missing-mass spectroscopy via the $(e,e'K^+)$ reaction at Jefferson Lab's experimental Hall A. The present experiment has higher sensitivity to the $nnΛ$-state investigation in terms of better precision by a factor of about three. The analysis shown in this article focuses on the derivation of the reaction cross-section for the $^3{\rm{H}}(γ^{*},K^+)\textrm{X}$ reaction. Events that were detected in an acceptance, where a Monte Carlo simulation could reproduce the data well ($|δp/p| < 4\%$), were analyzed to minimize the systematic uncertainty. No significant structures were observed with the acceptance cuts, and the upper limits of the production cross-section of the $nnΛ$ state were obtained to be $21$ and $31~\rm{nb/sr}$ at the $90\%$ confidence level when theoretical predictions of $(-B_Λ, Γ) = (0.25,0.8)$ and $(0.55, 4.7)$ MeV, respectively, were assumed. The cross-section result provides valuable information for examining the existence of $nnΛ$.

nucl-ex↗

arXiv2022

Multidimensional, high precision measurements of beam single spin asymmetries in semi-inclusive $π^{+}$ electroproduction off protons in the valence region

High precision measurements of the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering (SIDIS) from the proton have been performed using a 10.6~GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. We report here a high precision multidimensional study of single $π^{+}$ SIDIS data over a large kinematic range in Bjorken x, fractional energy and transverse momentum of the hadron as well as photon virtualities $Q^{2}$ ranging from $1-7\,$GeV$^{2}$. In particular, the structure function ratio $F^{\sinϕ}_{LU}/F_{UU}$ has been determined, where $F^{\sinϕ}_{LU}$ is a twist-3 quantity that can reveal novel aspects of emergent hadron mass and quark-gluon correlations within the nucleon. The data's impact on the evolving understanding of the underlying reaction mechanisms and their kinematic variation is explored using theoretical models for the different contributing transverse momentum dependent parton distribution functions.

hep-ex↗

arXiv2022

Deeply virtual Compton scattering cross section at high Bjorken $x_B$

We report high-precision measurements of the Deeply Virtual Compton Scattering (DVCS) cross section at high values of the Bjorken variable $x_B$. DVCS is sensitive to the Generalized Parton Distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton Form Factors (CFFs) of the nucleon as a function of $x_B$, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

hep-ph↗

arXiv2021

Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report

This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions. This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter

physics.ins-det↗

arXiv2021

Deep exclusive electroproduction of $π^0$ at high $Q^2$ in the quark valence regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of $x_B$ (0.36, 0.48 and 0.60) and $Q^2$ (3.1 to 8.4 GeV$^2$) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions $dσ_L/dt+εdσ_T/dt$, $dσ_{TT}/dt$, $dσ_{LT}/dt$ and $dσ_{LT'}/dt$ are extracted as a function of the proton momentum transfer $t-t_{min}$. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross-section throughout this kinematic range. The data are well described by calculations based on transversity Generalized Parton Distributions coupled to a helicity flip Distribution Amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

hep-ex↗

arXiv2021

Characterization of Muon and Electron Beams in the Paul Scherrer Institute PiM1 Channel for the MUSE Experiment

The MUon Scattering Experiment, MUSE, at the Paul Scherrer Institute, Switzerland, investigates the proton charge radius puzzle, lepton universality, and two-photon exchange, via simultaneous measurements of elastic muon-proton and electron-proton scattering. The experiment uses the PiM1 secondary beam channel, which was designed for high precision pion scattering measurements. We review the properties of the beam line established for pions. We discuss the production processes that generate the electron and muon beams, and the simulations of these processes. Simulations of the $π$/$μ$/$e$ beams through the channel using TURTLE and G4beamline are compared. The G4beamline simulation is then compared to several experimental measurements of the channel, including the momentum dispersion at the IFP and target, the shape of the beam spot at the target, and timing measurements that allow the beam momenta to be determined. We conclude that the PiM1 channel can be used for high precision $π$, $μ$, and $e$ scattering.

physics.ins-det↗

arXiv2021

First-time measurement of Timelike Compton Scattering

We present the first measurement of the Timelike Compton Scattering process, $γp\to p^\prime γ^* (γ^*\to e^+e^-) $, obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities $2.25<Q^{\prime 2}<9$ GeV$^2$, squared momentum transferred $0.1<-t<0.8$ GeV$^2$, and average total center-of-mass energy squared ${s}=14.5$ GeV$^2$. The photon beam polarization asymmetry, similar to the beam-spin asymmetry in Deeply Virtual Compton Scattering, is sensitive to the imaginary part of the Compton Form Factors and provides a way to test the universality of the Generalized Parton Distributions. The angular asymmetry of the decay leptons accesses the real part of the Compton Form Factors and thus the D-term in the parametrization of the Generalized Parton Distributions.

hep-ex↗

arXiv2021

Measurement of deeply virtual Compton scattering off Helium-4 with CLAS at Jefferson Lab

We report on the measurement of the beam spin asymmetry in the deeply virtual Compton scattering off $^4$He using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab using a 6 GeV longitudinally polarized electron beam incident on a pressurized $^4$He gaseous target. We detail the method used to ensure the exclusivity of the measured reactions, in particular the upgrade of CLAS with a radial time projection chamber to detect the low-energy recoiling $^4$He nuclei and an inner calorimeter to extend the photon detection acceptance at forward angles. Our results confirm the theoretically predicted enhancement of the coherent ($e^4$He$~\to~e'$$^4$He$'γ'$) beam spin asymmetries compared to those observed on the free proton, while the incoherent ($e^4$He$~\to~e'$p$'γ'$X$'$) asymmetries exhibit a 30$\%$ suppression. From the coherent data, we were able to extract, in a model-independent way, the real and imaginary parts of the only $^4$He Compton form factor, $\cal H_A$, leading the way toward 3D imaging of the partonic structure of nuclei.

nucl-ex↗