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DOE OSTI2020

Simulating Diverse HEP Workflows on Heterogeneous Architectures

We evaluate key patterns and estimate throughput bounds of simulated transformation of conventional high energy physics (HEP) data processing workflows to heterogeneous equivalents. The simulation parameter space includes the number of offloaded tasks, CPU/accelerator ratios of intra-task computations, offload latencies, and run time efficiency of offloaded computations. The simulation is performed for a diverse set of state-of-the-art event reconstruction scenarios from ATLAS, LHCb and CMS - the frontier HEP experiments of the Large Hadron Collider project.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

CMS Physics Results in the LHC Runs 2,3

The Large hadron Collider at CERN and four scientific collaborations: Alice, ATLAS, CMS, LHCb are in operation since September 2008. The accelerator delivered and the experiments processed trillions of events of proton-proton and heavy ions collisions and provided useful data for thousands of physics analyses and publications. The jewel of the published data is a discovery in 2012 of the long anticipated Higgs boson. During the operation time the regular acquisition of data was interleaved with two periods of maintenance, Long-shutdown-1 (2013-2015) and Long-shutdown-2 (2018-2022), which resulted in several improvements to the machine and the experiments. The CMS collaboration recorded to date two large physics datasets of pp collision data. The first dataset, called Run 2, was recorded between 2015 and 2018 with 140fb-1 of integrated luminosity taken at 13TeV of center of mass energy. The second dataset, called Run 3, has just started in 2022 and it has been recording pp collision data at 13.6 TeV of center of mass energy, with 80 fb-1 of data collected till the end of July 2023.For my presentation I selected the most recent results produced by CMS from Run2 and Run 3 which are covering the topics of Higgs boson properties, searches for new particles and additional scalars, top quark production and properties, and I am discussing other interesting models e.g. using SM particles as portals to the Dark matter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Forecasting dark showers at Belle II

Dark showers from strongly interacting dark sectors that confine at the GeV scale can give rise to novel signatures at e + e - colliders. In this work, we study the sensitivity of B factory experiments to dark showers produced through an effective interaction arising from a heavy off-shell mediator. We show that a prospective search for displaced vertices from GeV-scale long-lived particles at Belle II can improve the sensitivity to dark showers substantially compared to an existing search at BaBar. We compare the sensitivity of searches for displaced signals to searches for promptly produced resonances at BaBar and KLOE and calculate sensitivity projections for a single-photon search at Belle II to invisible dark showers produced through an effective interaction. The underlying structure of the effective interaction can be resolved at higher-energy experiments, where the mediator can be produced on-shell. To study the resulting constraints, we update electroweak precision bounds on kinetically mixed Z' bosons and reinterpret a search for low-mass di-muon resonances at LHCb in terms of dark showers. We find that LHCb and Belle II are most sensitive to different particle decay lengths, underscoring the complementarity of LHC and intensity frontier experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Workshop summary: Kaons@CERN 2023

Kaon physics is at a turning point – while the rare-kaon experiments NA62 and KOTO are in full swing, the end of their lifetime is approaching and the future experimental landscape needs to be defined. With HIKE, KOTO-II and LHCb-Phase-II on the table and under scrutiny, it is a very good moment in time to take stock and contemplate about the opportunities these experiments and theoretical developments provide for particle physics in the coming decade and beyond. This paper provides a compact summary of talks and discussions from the Kaons@CERN 2023 workshop, held in September 2023 at CERN.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Forward production of prompt neutrinos from charm in the atmosphere and at high energy colliders

The high-energy atmospheric neutrino flux is dominated by neutrinos from the decays of charmed hadrons produced in the forward direction by cosmic ray interactions with air nuclei. We evaluate the charm contributions to the prompt atmospheric neutrino flux as a function of the center-of-mass energy √s of the hadronic collision and of the center-of-mass rapidity y of the produced charm hadron. Uncertainties associated with parton distribution functions are also evaluated as a function of y. We find that the y coverage of LHCb for forward heavy-flavour production, complemented by the angular coverage of present and future forward neutrino experiments at the LHC, bracket the most interesting y regions for the prompt atmospheric neutrino flux. At √s = 14 TeV foreseen for the HL-LHC phase, nucleon collisions in air contribute to the prompt neutrino flux prominently below E ν ~ 10 7 GeV. Measurements of forward charm and/or forward neutrinos produced in hadron collisions up to √s = 100 TeV, which might become possible at the FCC, are relevant for the prompt atmospheric neutrino flux up to E ν = 10 8 GeV and beyond.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Expression of interest for the CODEX-b detector

Abstract This document presents the physics case and ancillary studies for the proposed CODEX-b long-lived particle (LLP) detector, as well as for a smaller proof-of-concept demonstrator detector, CODEX- $$\beta $$ β , to be operated during Run 3 of the LHC. Our development of the CODEX-b physics case synthesizes ‘top-down’ and ‘bottom-up’ theoretical approaches, providing a detailed survey of both minimal and complete models featuring LLPs. Several of these models have not been studied previously, and for some others we amend studies from previous literature: In particular, for gluon and fermion-coupled axion-like particles. We moreover present updated simulations of expected backgrounds in CODEX-b’s actively shielded environment, including the effects of shielding propagation uncertainties, high-energy tails and variation in the shielding design. Initial results are also included from a background measurement and calibration campaign. A design overview is presented for the CODEX- $$\beta $$ β demonstrator detector, which will enable background calibration and detector design studies. Finally, we lay out brief studies of various design drivers of the CODEX-b experiment and potential extensions of the baseline design, including the physics case for a calorimeter element, precision timing, event tagging within LHCb, and precision low-momentum tracking.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Modification of χ c 1 ( 3872 ) and ψ ( 2 S ) Production in p Pb Collisions at s NN = 8.16 TeV

The LHCb Collaboration measures production of the exotic hadron χ c 1 ( 3872 ) in proton-nucleus collisions for the first time. Comparison with the charmonium state ψ ( 2 S ) suggests that the exotic χ c 1 ( 3872 ) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify χ c 1 ( 3872 ) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron. © 2024 CERN, for the LHCb Collaboration 2024 CERN

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Semitauonic b-hadron decays: A lepton flavor universality laboratory

The study of lepton flavor universality violation (LFUV) in semitauonic b-hadron decays has become increasingly important in light of long-standing anomalies in their measured branching fractions, and the large datasets anticipated from the LHC experiments and Belle II. Here, in this review, a comprehensive survey of the experimental environments and methodologies for semitauonic LFUV measurements at the B factories and LHCb is undertaken, along with an overview of the theoretical foundations and predictions for a wide range of semileptonic decay observables. The future prospects of controlling systematic uncertainties down to the percent level, matching the precision of standard model (SM) predictions, are examined. Furthermore, new perspectives and caveats on combinations of the LFUV data are discussed and the world averages for the R(D(*)) ratios are revisited. Here it is demonstrated that different treatments for the correlations of uncertainties from D** excited states can vary the current 3σ tension with the SM within a 1σ range. Prior experimental overestimates of D**τν contributions may further exacerbate this. The precision of future measurements is also estimated; their power to exploit full differential information, and solutions to the inherent difficulties in self-consistent new physics interpretations of LFUV observables, are explored.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Modification of Χ c1 (3872) and ψ(2S) Production in p Pb Collisions at $\sqrt{S_{NN}}$ = 8.16 TeV

The LHCb Collaboration measures production of the exotic hadron Χ c1 (3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state ψ(2S) suggests that the exotic Χ c1 (3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify Χ c1 (3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Development of an MCP-Based Timing Layer for the LHCb ECAL Upgrade-2

The increase in instantaneous luminosity during the high-luminosity phase of the LHC represents a significant challenge for future detectors. A strategy to cope with high-pileup conditions is to add a fourth dimension to the measurements of the hits, by exploiting the time separation of the various proton–proton primary collisions. According to LHCb simulation studies, resolutions of about 10–20 picoseconds, at least an order of magnitude shorter than the average time span between primary interactions, would be greatly beneficial for the physics reach of the experiment. Microchannel plate (MCP) photomultipliers are compact devices capable of measuring the arrival time of charged particles with the required resolution. The technology of large-area picosecond photodetectors (LAPPDs) is under investigation to implement a timing layer that can be placed within a sampling calorimeter module with the purpose of measuring the arrival time of electromagnetic showers. LAPPD performances, using a Gen-I tile with a delay-line anode and a Gen-II with a capacitively coupled anode, have been measured thoroughly both with laser (wavelength of 405 nm and pulse width of 27.5 ps FWHM) and high-energy electron (1–5.8 GeV) beams. Time resolutions of the order of 30 ps for single photoelectrons and 15 ps for electromagnetic showers initiated by 5-GeV electrons, as measured at the shower maximum, are obtained.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Far-forward neutrinos at the Large Hadron Collider

We present a new calculation of the energy distribution of high-energy neutrinos from the decay of charm and bottom hadrons produced at the Large Hadron Collider (LHC). In the kinematical region of very forward rapidities, heavy-flavor production and decay is a source of tau neutrinos that leads to thousands of charged-current tau neutrino events in a 1 m long, 1 m radius lead neutrino detector at a distance of 480 m from the interaction region. In our computation, next-to-leading order QCD radiative corrections are accounted for in the production cross-sections. Non-perturbative intrinsic-kT effects are approximated by a simple phenomenological model introducing a Gaussian kT-smearing of the parton distribution functions, which might also mimic perturbative effects due to multiple initial-state soft-gluon emissions. The transition from partonic to hadronic states is described by phenomenological fragmentation functions. To study the effect of various input parameters, theoretical predictions for D± s production are compared with LHCb data on double-differential cross-sections in transverse momentum and rapidity. The uncertainties related to the choice of the input parameter values, ultimately affecting the predictions of the tau neutrino event distributions, are discussed. We consider a 3+1 neutrino mixing scenario to illustrate the potential for a neutrino experiment to constrain the 3+1 parameter space using tau neutrinos and antineutrinos. We find large theoretical uncertainties in the predictions of the neutrino fluxes in the far-forward region. Untangling the effects of tau neutrino oscillations into sterile neutrinos and distinguishing a 3+1 scenario from the standard scenario with three active neutrino flavours, will be challenging due to the large theoretical uncertainties from QCD.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Far-forward neutrinos at the Large Hadron Collider

We present a new calculation of the energy distribution of high-energy neutrinos from the decay of charm and bottom hadrons produced at the Large Hadron Collider (LHC). In the kinematical region of very forward rapidities, heavy-flavor production and decay is a source of tau neutrinos that leads to thousands of charged-current tau neutrino events in a 1 m long, 1 m radius lead neutrino detector at a distance of 480 m from the interaction region. In our computation, next-to-leading order QCD radiative corrections are accounted for in the production cross-sections. Non-perturbative intrinsic-k T effects are approximated by a simple phenomenological model introducing a Gaussian k T -smearing of the parton distribution functions, which might also mimic perturbative effects due to multiple initial-state soft-gluon emissions. The transition from partonic to hadronic states is described by phenomenological fragmentation functions. To study the effect of various input parameters, theoretical predictions for $D^{±}_s$ production are compared with LHCb data on double-differential cross-sections in transverse momentum and rapidity. The uncertainties related to the choice of the input parameter values, ultimately affecting the predictions of the tau neutrino event distributions, are discussed. We consider a 3+1 neutrino mixing scenario to illustrate the potential for a neutrino experiment to constrain the 3+1 parameter space using tau neutrinos and antineutrinos. We find large theoretical uncertainties in the predictions of the neutrino fluxes in the far-forward region. Untangling the effects of tau neutrino oscillations into sterile neutrinos and distinguishing a 3+1 scenario from the standard scenario with three active neutrino flavours, will be challenging due to the large theoretical uncertainties from QCD.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Centrality determination in heavy-ion collisions with the LHCb detector

The centrality of heavy-ion collisions is directly related to the created medium in these interactions. A procedure to determine the centrality of collisions with the LHCb detector is implemented for lead-lead collisions at √ s NN = 5 TeV and lead-neon fixed-target collisions at √ s NN = 69 GeV. The energy deposits in the electromagnetic calorimeter are used to determine and define the centrality classes. The correspondence between the number of participants and the centrality for the lead-lead collisions is in good agreement with the correspondence found in other experiments, and the centrality measurements for the lead-neon collisions presented here are performed for the first time in fixed-target collisions at the LHC.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Simultaneous determination of CKM angle γ and charm mixing parameters

A combination of measurements sensitive to the CP violation angle γ of the Cabibbo-Kobayashi-Maskawa unitarity triangle and to the charm mixing parameters that describe oscillations between D 0 and $ \overline{D} $ 0 mesons is performed. Results from the charm and beauty sectors, based on data collected with the LHCb detector at CERN’s Large Hadron Collider, are combined for the first time. This method provides an improvement on the precision of the charm mixing parameter y by a factor of two with respect to the current world average. The charm mixing parameters are determined to be $ x=\left({0.400}_{-0.053}^{+0.052}\right)\% $ and y = $ \left({0.630}_{-0.030}^{+0.033}\right)\% $. The angle γ is found to be γ = ($ 65.4_{-4.2}^{+3.8} $)° and is the most precise determination from a single experiment.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

PHENIX Probing QCD Matter Through Heavy Flavor and Quarkonium at RHIC

Recent results from the PHENIX experiment on heavy flavors and quarkonia production in p + Al, p + Au, d + Au, and Au + Au collision systems at psNN = 200 GeV are summarized. The results are carried out by the measurements of the nuclear modification factors and elliptic flow. The nuclear modification factors measurements give insight into the energy loss of heavy quarks in the quark-gluon plasma medium along their path lengths. The elliptic flow measurements are a good tool to investigate the coupling of heavy quarks with the medium. The measurements are presented as a function of centrality, rapidity, and transverse momentum. The interpretations of the results in light of our current theoretical models, and comparison to LHCb and ALICE measurements are presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Prompt and non-prompt J/ψ production cross sections at midrapidity in proton-proton collisions at $ \sqrt{\mathrm{s}} $ = 5.02 and 13 TeV

The production of J /ψ is measured at midrapidity ( |y| < 0 . 9) in proton-proton collisions at \( \sqrt{s} \) = 5 . 02 and 13 TeV, through the dielectron decay channel, using the ALICE detector at the Large Hadron Collider. The data sets used for the analyses correspond to integrated luminosities of \( \mathcal{L} \) int = 19.4 ± 0.4 nb - 1 and \( \mathcal{L} \) int = 32.2 ± 0.5 nb - 1 at \( \sqrt{s} \) = 5 . 02 and 13 TeV, respectively. The fraction of non-prompt J /ψ mesons, i.e. those originating from the decay of beauty hadrons, is measured down to a transverse momentum p T = 2 GeV /c (1 GeV /c ) at \( \sqrt{s} \) = 5 . 02 TeV (13 TeV). The p T and rapidity ( y ) differential cross sections, as well as the corresponding values integrated over p T and y , are carried out separately for prompt and non-prompt J /ψ mesons. The results are compared with measurements from other experiments and theoretical calculations based on quantum chromodynamics (QCD). The shapes of the p T and y distributions of beauty quarks predicted by state-of-the-art perturbative QCD models are used to extrapolate an estimate of the \( \mathrm{b}\overline{\mathrm{b}} \) pair cross section at midrapidity and in the total phase space. The total \( \mathrm{b}\overline{\mathrm{b}} \) cross sections are found to be \( {\sigma}_{\mathrm{b}\overline{\mathrm{b}}} \) = 541 ± 45 (stat . ) ± 69 \( {\left(\mathrm{syst}.\right)}_{-12}^{+10} \) (extr . ) μ b and \( {\sigma}_{\mathrm{b}\overline{\mathrm{b}}} \) = 218 ± 37 (stat . ) ± 31 \( {\left(\mathrm{syst}.\right)}_{-9.1}^{+8.2} \) (extr . ) μ b at \( \sqrt{s} \) = 13 and 5.02 TeV, respectively. The value obtained from the combination of ALICE and LHCb measurements in pp collisions at \( \sqrt{s} \) = 13 TeV is also provided.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Measurement of the polarizations of prompt and non-prompt J/ψ and ψ ( 2S ) mesons produced in pp collisions at s = 13 TeV

The polarizations of prompt and non-prompt Image 2 and ψ ( 2S ) mesons are measured in proton-proton collisions at s = 13 TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3 fb − 1 . Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, λ ϑ , is measured as a function of the transverse momentum, p T , of the charmonium states, in the 25–120 and 20–100 GeV ranges for the Image 2 and ψ ( 2S ) , respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for p T ≳ 25 GeV , the non-prompt Image 2 and ψ ( 2S ) are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for p T exceeding 30 times the Image 2 mass, where λ ϑ tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at s = 7 TeV, the prompt polarizations show a significant variation with p T , at low p T .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Forward neutrinos from charm at the Large Hadron Collider

The currently operating FASER experiment and the planned Forward Physics Facility (FPF) will detect a large number of neutrinos produced in proton-proton collisions at the LHC. In this work, we estimate neutrino fluxes at these detectors from charm meson decays, which will be particularly important for the ν e and ν τ channels. We make prediction using both the next-to-leading order collinear factorization and the k T -factorization approaches to model the production of charm quarks as well as different schemes to model their hadronization into charm hadrons. In particular, we emphasize that a sophisticated modeling of hadronization involving beam remnants is needed for predictions at FASER and FPF due to the sensitivity to the charm hadron production at low transverse momenta and very forward rapidity. As example, we use the string fragmentation approach implemented in 8. While both standard fragmentation functions and 8 are able to describe LHCb data, we find that 8 predicts significantly higher rate of high energy neutrinos, highlighting the importance of using the correct hadronization model when making predictions. Published by the American Physical Society 2024

Astronomy & Astrophysics↗