Integrated Luminosity Research Articles

Applying High‐Speed Video Images to Inverse Channel Base Current Based on NARX Neural Network

AbstractThe high‐speed video (HSV) images were taken as the input data of the nonlinear autoregressive network (NARX) to reconstruct the return‐stroke channel base current (CBC). The integrated luminosity (IL) of discharge channel is firstly obtained by summing the pixel values in HSV images, and the correlation between the IL and CBC is analyzed as well. Then, a NARX model is trained by taking the IL and CBC as the input and output data, respectively. With the input of the IL of another discharge channel, the trained NARX model is applied to inverse the corresponding CBC. The inversed result suggests that the proposed method can be used to infer the CBC that was not yet measured.

Сравнение модельных расчетов интенсивностей свечения различных систем полос молекулярного кислорода с экспериментальными данными, полученными с космического шаттла «Дискавери»

The results of theoretical calculations of the emission intensities of various states of excited molecular oxygen are compared with experimental data on the nighttime glow of O2 obtained from the Space Shuttle Discovery. The calculated values of the integral luminosity (histograms) for the considered months of the Earth's year are presented. It is shown that at the middle latitudes of the Earth during the period of low solar activity, the maximum values of the integrated luminosity for Herzberg I and Chamberlain bands are in July, for Atmospheric bands — in October.

Improved Resistive Plate Chambers for the upgrade of the CMS muon detector

Several upgrades of the Resistive Plate Chamber (RPC) system of the Compact Muon Solenoid (CMS) experiment are currently being implemented to ensure a highly performing muon system during the upcoming High Luminosity phase of the Large Hadron Collider which will have an increased integrated luminosity of 3000 fb−1. The expected experimental conditions in that period present a challenge for the entire CMS detection system. To extend the RPC coverage, an improved version of the already existing RPCs will be installed in the forward region of the 3rd and 4th endcap disks. The current overall status of this CMS RPC upgrade project is presented.

Higgs boson precision measurements at a 125 GeV muon collider

The $s$-channel resonant production of the Higgs boson at a 125 GeV muon collider enables a unique way to determine the Higgs properties. However, a clear picture of the achievable Higgs precision has not yet been established. We perform a phenomenological study of the Higgs measurements at such a resonant muon collider Higgs factory and present a systematic, detailed, and consistent extraction of Higgs precision measurements. Many new aspects about the line shape scan, including the scaling with luminosity, optimal scan range, minimal scan steps, correlations with exclusive measurement, effective cross section modeling, etc., are quantitatively studied in this work. All major exclusive Higgs channels are simulated and analyzed with Standard Model background, detection efficiencies, acceptance, angular distributions, and cross-channel correlations. Global analyses of the Higgs couplings are performed in the $\ensuremath{\kappa}$ framework and the effective-field-theory one. The results suggest that the 125 GeV muon-collider Higgs factory provides significant improvement to the Higgs coupling reach of the High-Luminosity LHC and provides independent and distinct Higgs precision information concerning future ${e}^{+}{e}^{\ensuremath{-}}$ colliders. We report results for both 5 and $20\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ integrated luminosity. These results provide comprehensive and quantitative physics understandings helpful in planning for the muon collider road map and global high-energy physics programs.

Decoding dark matter at future e+e− colliders

We explore the potential of the ${e}^{+}{e}^{\ensuremath{-}}$ colliders to discover dark matter and determine its properties such as mass and spin. For this purpose we study spin zero and spin one-half cases of dark matter $D$, which belongs to the $SU(2)$ weak doublet and therefore has the charged doublet partner ${D}^{+}$. For the case of scalar dark matter we chose inert doublet model, while for the case of fermion dark matter we suggest the new minimal fermion dark matter model with only three parameters. We choose two benchmarks for the models under study, which provide the correct amount of observed dark matter (DM) relic density and consistent with the current DM searches. We focus on the particular process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{+}{D}^{\ensuremath{-}}\ensuremath{\rightarrow}DD{W}^{+}{W}^{\ensuremath{-}}\ensuremath{\rightarrow}DD(q\overline{q})({\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\nu})$ at the 500 GeV ILC collider that gives rise to the ``$\mathrm{dijet}+\ensuremath{\mu}+{\overline{)E}}_{T}$'' signature and study it at the level of fast detector simulation, taking into account bremsstrahlung and ISR effects. We have found that two kinematical observables---the energy of the muon ${E}_{\ensuremath{\mu}}$ and the angular distribution of the $W$ boson, reconstructed from dijet $\mathrm{cos}{\ensuremath{\theta}}_{jj}$ are very powerful in determination of DM mass and spin, respectively. In particular we have demonstrated that in the case of fermion DM, the masses can be measured with a few percent accuracy already at $500\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ integrated luminosity. At the same time, the scalar DM model which has about an order of magnitude lower signal, requires about a factor of 40 higher luminosity to reach the same accuracy in the mass measurement. We have found that one can distinguish fermion and scalar DM scenarios with about $2\text{ }\text{ }{\mathrm{ab}}^{\ensuremath{-}1}$ total integrated luminosity or less without using the information on the cross sections for benchmarks under study. The methods of the determination of DM properties which we suggest here are generic for the models where DM and its partner belong to the weak multiplet and can be applied to explore various DM models at future ${e}^{+}{e}^{\ensuremath{-}}$ colliders.

Study of Events with an Electron, Muon, and Two Hadron Jets in the Final State with an Integrated Luminosity of a 139 fb–1 in pp Collisions at $$\sqrt s $$ = 13 TeV with the ATLAS Detector at the LHC

Study of Events with an Electron, Muon, and Two Hadron Jets in the Final State with an Integrated Luminosity of a 139 fb–1 in pp Collisions at $$\sqrt s $$ = 13 TeV with the ATLAS Detector at the LHC

Analysis of the anomalous quartic WWWW couplings at the LHeC and the FCC-he

The quartic gauge boson couplings that identify the strengths of the gauge boson self-interactions are exactly determined by the non-Abelian gauge nature of the Standard Model. The examination of these couplings at $ep$ collisions with high center-of-mass energy and high integrated luminosity provides an important opportunity to test the validity of the Standard Model and the existence of new physics beyond the Standard Model. The quartic gauge boson couplings can contribute directly to multi-boson production at colliders. Therefore, we examine the potential of the process $ep \rightarrow \nu_{e}W^{+}W^{-} j$ at the Large Hadron Electron Collider and the Future Circular Collider-hadron electron to study non-standard $WWWW$ couplings in a model independent way by means of the effective Lagrangian approach. We present an investigation on measuring $W^{+}W^{-}$ production in pure leptonic and semileptonic decay channels. In addition, we calculate the sensitivity limits at $95\%$ Confidence Level on the anomalous $\frac{f_{M0}}{\Lambda^{4}}$, $\frac{f_{M1}}{\Lambda^{4}}$, $\frac{f_{M7}}{\Lambda^{4}}$, $\frac{f_{S0}}{\Lambda^{4}}$, $\frac{f_{S1}}{\Lambda^{4}}$, $\frac{f_{T0}}{\Lambda^{4}}$, $\frac{f_{T1}}{\Lambda^{4}}$ and $\frac{f_{T2}}{\Lambda^{4}}$ couplings obtained by dimension-8 operators through the process $ep \rightarrow \nu_{e}W^{+}W^{-} j$ for the Large Hadron Electron Collider and the Future Circular Hadron Electron Collider's different center-of-mass energies and integrated luminosities. Our results show that with the process $ep \rightarrow \nu_{e}W^{+}W^{-} j$ at the Large Hadron Electron Collider and the Future Circular Collider-hadron electron the sensitivity estimated on the anomalous $WWWW$ couplings can be importantly strengthened.

A new feasible dark matter region in the singlet scalar scotogenic model

We study a simplest viable dark matter model with a real singlet scalar, vector-like singlet and a doublet lepton. We find a considerable enhancement in the allowed region of the scalar dark matter parameter spaces under the influence of the new Yukawa coupling. The Yukawa coupling associate with the fermion sector heavily dominant the dark matter parameter spaces satisfying the current relic density of the Universe. Dilepton+E̸T signature arising from the new fermionic sector can observe at Large Hadron Collider (LHC). We perform such analysis in the context of 14 TeV LHC experiments with a future integrated luminosity of 3000 fb−1. We found that a large region of the parameter spaces can be probed by the LHC experiments. The projected exclusion/discovery reach of direct heavy charged fermion searches in this channel is analyzed by performing a detailed cut based collider analysis. The projected exclusion contour reaches up to 1050−1380GeV for 3000 fb−1 for a light dark matter O(10) GeV from searches in the pp→E1±E1∓,E1±→l±S→ll+E̸T channel.

Pinning down the gauge boson couplings in WW\u03b3 production using forward proton tagging

In this paper, we explore the potential of the LHC to measure the rate of pp → p WWγ p process, also to probe the new effective couplings contributing to the WWγ and WWγγ vertices. The analysis is performed at the sqrt{s} = 13 TeV, in the dileptonic decay channel, and assuming 300 fb−1 integrated luminosity (IL). In addition to the presence of two opposite sign leptons, a photon, and missing energy, the distinctive signature of this process is the presence of two intact protons flying few millimeters from the initial beam direction in both sides of interaction points which suppress the background process effectively. To exploit this feature of signal we benefit from forward detectors (FDs) placed about 200 meters from the interaction point to register the kinematics of tagged protons. In order to overcome the major sources of backgrounds, we introduced three categories of selection cuts dealing with objects that strike the central detector, protons hitting the FDs, and correlations of central objects and protons, respectively. We also evaluate the probability of pile-up protons to be tagged in the FDs as a function of the mean number of pile-up. Then the sensitivity of the LHC to observe this process and constraints on multi-boson effective couplings are extracted. The obtained expected limits show very good improvements for dimension-8 quartic couplings and competitive bounds on dimension-6 anomalous triple couplings w.r.t. the current experimental limits. Therefore, we propose this process to the LHC experiments as a sensitive and complementary channel to study the multi-gauge boson couplings.

Probing the charm Yukawa coupling at future e−p and e+e− colliders

Large Hadron Collider (LHC) has provided direct evidence of Yukawa couplings between the third generation charged fermions and the 125 GeV Higgs boson. Whether the first two generation charged fermions arise from exactly the same mechanism becomes the next interesting question. Therefore, direct measurements of charm or muon Yukawa couplings will be crucial to answering this puzzle. The charm Yukawa measurement at the LHC suffers from severe QCD background and it is extremely difficult to reach the sensitivity. In this paper, we compare the potential of probing charm Yukawa coupling at the two proposed future "Higgs Factory" experiments, the Large Hadron electron Collider (LHeC) and Circular electron positron collider (CEPC). At the LHeC, Higgs bosons will be produced via weak boson fusion and the energetic forward jet may suppress the background significantly. However, due to huge $\gamma-g$ scattering background, the potential of LHeC search is still limited. With $-80\%$ polarized electron beam of 60 GeV, the signal significance can only reach $2\sigma$ for $ \kappa_{c}\simeq 1$ with a 3 ab$^{-1}$ integrated luminosity. In comparison, measurement at the CEPC can then reach $8.0\sigma$ for $\kappa_{c}\simeq 1$ with a 2 ab$^{-1}$ of data.

Probing an additional bottom Yukawa coupling via bg→bA→bZH signature

The recent discovery of the bottom quark Yukawa coupling ($hbb$) of the 125 GeV scalar motivates one to search for extra bottom Yukawa coupling that may exist in the nature. The two Higgs doublet model without a discrete $Z_2$ symmetry allows the possibility of additional bottom Yukawa coupling $\rho_{bb}$. We show that $\rho_{bb}$ can be searched directly at the LHC via $bg\to b A \to b Z H$ and $gg \to b \bar b A \to b \bar b Z H$ processes, where $A$ and $H$ are the CP-odd and CP-even scalars respectively. We find that the $bg\to b A \to b Z H$ process could be discovered with $\sim300$ fb$^{-1}$ integrated luminosity if $ m_A \sim 300$ GeV, while the latter process may emerge in the high luminosity LHC (HL-LHC) data. A discovery might touch upon the parameter space required for the electroweak baryogenesis.

Assessment of the performance of High-Luminosity LHC operational scenarios: integrated luminosity and effective pile-up density

The High-Luminosity Large Hadron Collider (HL-LHC) experiments will operate at unprecedented levels of event pile-up from proton–proton collisions at 14 TeV centre-of-mass energy. In this paper, we study the performance of the baseline and a series of alternative scenarios in terms of the delivered integrated luminosity and its quality (pile-up density). A new figure-of-merit is introduced, the effective pile-up density, a concept that reflects the expected detector efficiency in the reconstruction of event vertices for a given operational scenario, acting as a link between the machine and experimental sides. Alternative scenarios have been proposed either to improve the baseline performance or to provide operational schemes in the case of particular limitations. Simulations of the evolution of their optimum fills with the latest set of parameters of the HL-LHC are performed with β*-levelling, and the results are discussed in terms of both the integrated luminosity and the effective pile-up density. The crab kissing scheme, a proposed scenario for pile-up density control, is re-evaluated under this new perspective with updated beam and optics parameters. Estimates on the expected integrated luminosity due to the impact of crab cavity noise, full crab crossing, and reduced cross section for burn-off, are also presented.

Observation of Single Top Quark Production in Association with a Z Boson in Proton-Proton Collisions at sqrt[s]=13 TeV.

The observation of single top quark production in association with a Z boson and a quark (tZq) is reported. Events from proton-proton collisions at a center-of-mass energy of 13TeV containing three charged leptons (either electrons or muons) and at least two jets are analyzed. The data were collected with the CMS detector in 2016 and 2017 and correspond to an integrated luminosity of 77.4fb^{-1}. The increased integrated luminosity, a multivariate lepton identification, and a redesigned analysis strategy improve significantly the sensitivity of the analysis compared to previous searches for tZq production. The tZq signal is observed with a significance well over 5 standard deviations. The measured tZq production cross section is σ(pp→tZq→tℓ^{+}ℓ^{-}q)=111±13(stat)_{-9}^{+11}(syst) fb, for dilepton invariant masses above 30GeV, in agreement with the standard model expectation.

Detecting the light gauge boson Zμτ via Higgstrahlung process in the [formula omitted] model at e+e− colliders

We consider the generation of the new light gauge boson Zμτ predicted by the U(1)Lμ−Lτ model via Zh1 associated production followed by the SM-like Higgs boson h1 decaying into a Zμτ pair process at future high-energy e+e− colliders. Taking into account the experimental constraints on the free parameters of the U(1)Lμ−Lτ model and the beam polarizations P(e−,e+)=(−0.8,0.3), P(e−,e+)=(0.8,−0.3) and P(e−,e+)=(0,0), we calculate the cross sections of Zμτ production and further investigate the observability of Zμτ production through the leptonic channel ▪ and hadronic channel ▪ at e+e− colliders. We find that the signal significance above 5σ for Zμτ detection can be achieved via both these two processes with appropriate parameter values and high integrated luminosity, and that the hadronic channel can offer a more detectable signature compared with the leptonic channel.

Search for the rare decay of B+→ℓ+νℓγ with improved hadronic tagging

We present the result of the search for the rare $B$ meson decay of $B^+ \to \ell^{\,+} \nu_{\ell} \gamma$ with $\ell =e,\mu$. For the search the full data set recorded by the Belle experiment of $711 \, \mathrm{fb}^{-1}$ integrated luminosity near the $\Upsilon (4S)$ resonance is used. Signal candidates are reconstructed for photon energies $E_{\gamma}$ larger than $1 \, \mathrm{GeV}$ using a novel multivariate tagging algorithm. The novel algorithm fully reconstructs the second $B$ meson produced in the collision using hadronic modes and was specifically trained to recognize the signal signature in combination with hadronic tag-side $B$ meson decays. This approach greatly enhances the performance. Background processes that can mimic this signature, mainly charmless semileptonic decays and continuum processes, are suppressed using multivariate methods. The number of signal candidates is determined by analyzing the missing mass squared distribution as inferred from the signal side particles and the kinematic properties of the tag-side $B$ meson. No significant excess over the background-only hypothesis is observed and upper limits on the partial branching fraction $ \Delta \mathcal{B} $ with $E_{\gamma}> 1 \, \mathrm{GeV}$ individually for electron and muon final states as well as for the average branching fraction of both lepton final states are reported. We find a Bayesian upper limit of $\Delta \mathcal{B}( B^{+} \to \ell^{\, +} \nu_{\ell} \gamma) < 3.0 \times 10^{-6}$ at 90% CL and also report an upper limit on the first inverse moment of the light-cone distribution amplitude of the $B$ meson of $\lambda_B$ at 90% CL.

Light charged Higgs boson with dominant decay to quarks and its search at the LHC and future colliders

The possibility of a light charged Higgs boson $H^\pm$ that decays predominantly to quarks ($cs$ and/or $cb$) and with a mass in the range 80 GeV $\le m_{H^\pm} \le 90$ GeV is studied in the context of Three-Higgs-Doublet Models (3HDMs). At present the Large Hadron Collider (LHC) has little sensitivity to this scenario, and currently the best constraints are from LEP2 and Tevatron searches. The branching ratio of $H^\pm\to cb$ can be dominant in two of the five types of 3HDM, and we determine the parameter space where this occurs. The decay $H^\pm\to cb$ has recently been searched for at the LHC for the first time, and with increased integrated luminosity one would expect sensitivity to the region 80 GeV $\le m_{H^\pm} \le 90$ GeV due to the smaller backgrounds with respect to $H^\pm\to cs$ decays.

Belle II Experiment: Status and Upgrade

The Belle II experiment at the asymmetric e $$^{+}$$ e $$^{-}$$ SuperKEKB collider will start its operation in 2018 and will collect data of 50 ab $$^{-1}$$ integrated luminosity. This high luminosity will shed light on new physics beyond the Standard Model via high precision measurements of heavy flavor decays and searches for rare signal events. In this work, we present the status of the SuperKEKB and the Belle II detector construction. The expected sensitivity to new physics of the Belle II data set will also be discussed.

Probing the Higgs boson-gluon coupling via the jet energy profile at e+e− colliders

The effective coupling of the Higgs boson to a gluon pair is one of the most important parameters to test the Standard Model and search for the new physics beyond. In this paper, we propose several new observables based on the jet energy profile to extract the effective coupling. The statistical uncertainties of the effective coupling extracted by using new observables are derived and estimated based on the simulation at the future $e^+e^-$ collider for $250$ GeV center-of-mass energy and 5 ab$^{-1}$ integrated luminosity. We found that the statistical uncertainties of effective coupling via the optimized observable can reach about $1.6\%$ in the channels of a $Z$ boson decaying to lepton pairs and is reduced by $52\%$ compared to the relevant uncertainties in the conventional approach. These new observables potentially can be helpful for the measurement of effective coupling at future $e^+e^-$ colliders.

First beam tests of prototype silicon modules for the CMS High Granularity Endcap Calorimeter

The High Luminosity phase of the Large Hadron Collider will deliver 10 times more integrated luminosity than the existing collider, posing significant challenges for radiation tolerance and event pileup on detectors, especially for forward calorimetry. As part of its upgrade program, the Compact Muon Solenoid collaboration is designing a high-granularity calorimeter (HGCAL) to replace the existing endcap calorimeters. It will feature unprecedented transverse and longitudinal readout and triggering segmentation for both electromagnetic and hadronic sections. The electromagnetic section and a large fraction of the hadronic section will be based on hexagonal silicon sensors of 0.5–1 cm2 cell size, with the remainder of the hadronic section being based on highly-segmented scintillators with silicon photomultiplier readout. The intrinsic high-precision timing capabilities of the silicon sensors will add an extra dimension to event reconstruction, especially in terms of pileup rejection. First hexagonal silicon modules, using the existing Skiroc2 front-end ASIC developed for CALICE, have been tested in beams at Fermilab and CERN in 2016. We present results from these tests, in terms of system stability, calibration with minimum-ionizing particles and resolution (energy, position and timing) for electrons, and the comparisons of these quantities with GEANT4-based simulation.

Search for magnetic monopoles with the MoEDAL forward trapping detector in 2.11 fb−1 of 13 TeV proton–proton collisions at the LHC

We update our previous search for trapped magnetic monopoles in LHC Run 2 using nearly six times more integrated luminosity and including additional models for the interpretation of the data. The MoEDAL forward trapping detector, comprising 222 kg of aluminium samples, was exposed to 2.11 fb−1 of 13 TeV proton–proton collisions near the LHCb interaction point and analysed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges equal to the Dirac charge or above are excluded in all samples. The results are interpreted in Drell–Yan production models for monopoles with spins 0, 1/2 and 1: in addition to standard point-like couplings, we also consider couplings with momentum-dependent form factors. The search provides the best current laboratory constraints for monopoles with magnetic charges ranging from two to five times the Dirac charge.