The physics goal of the strong interaction program of the NA61/SHINE experiment at the CERN Super Proton Synchrotron (SPS) is to study the phase diagram of hadronic matter by a scan of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents differential inclusive spectra of transverse momentum, transverse mass and rapidity of $\pi^{-}$ mesons produced in $central$ ${}^{40}$Ar+${}^{45}$Sc collisions at beam momenta of 13$A$, 19$A$, 30$A$, 40$A$, 75$A$ and 150$A$ GeV/$c$. Energy and system size dependence of parameters of these distributions -- mean transverse mass, the inverse slope parameter of transverse mass spectra, width of the rapidity distribution and mean multiplicity -- are presented and discussed. Furthermore, the dependence of the ratio of the mean number of produced pions to the mean number of wounded nucleons on the collision energy was derived. The results are compared to predictions of several models.
Uncorrected double-differential spectra n[h−]raw/dy/dpT of negatively charged hadrons produced in the 5% Ar+Sc collisions with the smallest EPSD energy at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A GeV/c
Uncorrected double-differential spectra n[h−]raw/dy/dpT of negatively charged hadrons produced in the 5% Ar+Sc collisions with the smallest EPSD energy at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A GeV/c
Uncorrected double-differential spectra n[h−]raw/dy/dpT of negatively charged hadrons produced in the 5% Ar+Sc collisions with the smallest EPSD energy at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A GeV/c
Modifications to the distribution of charged particles with respect to high transverse momentum ($p_\mathrm{T}$) jets passing through a quark-gluon plasma are explored using the CMS detector. Back-to-back dijets are analyzed in lead-lead and proton-proton collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV via correlations of charged particles in bins of relative pseudorapidity and angular distance from the leading and subleading jet axes. In comparing the lead-lead and proton-proton collision results, modifications to the charged-particle relative distance distribution and to the momentum distributions around the jet axis are found to depend on the dijet momentum balance $x_j$, which is the ratio between the subleading and leading jet $p_\mathrm{T}$. For events with $x_j$$\approx$ 1, these modifications are observed for both the leading and subleading jets. However, while subleading jets show significant modifications for events with a larger dijet momentum imbalance, much smaller modifications are found for the leading jets in these events.
The distribution of charged particle yields within $|\Delta\varphi| < 1.0$ correlated with the leading jets as a function of $\Delta\eta$ in the 0-10 % centrality bin in PbPb collisions. The results are shown in different dijet momentum balance bins.
The distribution of charged particle yields within $|\Delta\varphi| < 1.0$ correlated with the leading jets as a function of $\Delta\eta$ in the 10-30 % centrality bin in PbPb collisions. The results are shown in different dijet momentum balance bins.
The distribution of charged particle yields within $|\Delta\varphi| < 1.0$ correlated with the leading jets as a function of $\Delta\eta$ in the 30-50 % centrality bin in PbPb collisions. The results are shown in different dijet momentum balance bins.
The results of a search for gluino and squark pair production with the pairs decaying via the lightest charginos into a final state consisting of two $W$ bosons, the lightest neutralinos ($\tilde\chi^0_1$), and quarks, are presented. The signal is characterised by the presence of a single charged lepton ($e^{\pm}$ or $\mu^{\pm}$) from a $W$ boson decay, jets, and missing transverse momentum. The analysis is performed using 139 fb$^{-1}$ of proton-proton collision data taken at a centre-of-mass energy $\sqrt{s}=13$ TeV delivered by the Large Hadron Collider and recorded by the ATLAS experiment. No statistically significant excess of events above the Standard Model expectation is found. Limits are set on the direct production of squarks and gluinos in simplified models. Masses of gluino (squark) up to 2.2 TeV (1.4 TeV) are excluded at 95% confidence level for a light $\tilde\chi^0_1$.
Post-fit $m_{T}$ distribution in the SR 2J b-veto N-1 region. N-1 refers to all cuts except for the requirement on $m_T$ being applied. Uncertainties include statistical and systematic uncertainties. The value 9999 is used as a placeholder for infinity.
Post-fit $m_{T}$ distribution in the SR 2J b-tag N-1 region. N-1 refers to all cuts except for the requirement on $m_T$ being applied. Uncertainties include statistical and systematic uncertainties. The value 9999 is used as a placeholder for infinity.
Post-fit $m_{T}$ distribution in the SR 4J b-veto N-1 region. N-1 refers to all cuts except for the requirement on $m_T$ being applied. Uncertainties include statistical and systematic uncertainties. The value 9999 is used as a placeholder for infinity.
Global polarization of $\Xi$ and $\Omega$ hyperons has been measured for the first time in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV. The measurements of the $\Xi^-$ and $\bar{\Xi}^+$ hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay $\Xi\rightarrow\Lambda+\pi$, as well as by measuring the polarization of the daughter $\Lambda$-hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over $\Xi^-$ and $\bar{\Xi}^+$, is measured to be $\langle P_\Xi \rangle = 0.47\pm0.10~({\rm stat.})\pm0.23~({\rm syst.})\,\%$ for the collision centrality 20%-80%. The $\langle P_\Xi \rangle$ is found to be slightly larger than the inclusive $\Lambda$ polarization and in reasonable agreement with a multi-phase transport model (AMPT). The $\langle P_\Xi \rangle$ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. The global polarization of $\Omega$, $\langle P_\Omega \rangle = 1.11\pm0.87~({\rm stat.})\pm1.97~({\rm syst.})\,\%$ was obtained by measuring the polarization of daughter $\Lambda$ in the decay $\Omega \rightarrow \Lambda + K$, assuming the polarization transfer factor $C_{\Omega\Lambda}=1$.
$\Xi$ and $\Omega$ global polarization in Au+Au collisions at 200 GeV. Decay parameter from PDG2020, $\alpha_{\Xi}$=-$\alpha_{\bar{\Xi}}$=-0.401, is used.
The energy dependence of $\Lambda$ and $\bar{\Lambda}$ global polarization. Note that the results from previous measurements are rescaled using updated decay parameters (PDG2020), $\alpha_{\Lambda}$=0.732 and $\alpha_{\bar{\Lambda}}$=-0.758. The original data can be found in <a href="https://www.hepdata.net/record/ins1510474">this page</a>.
Centrality dependence of $\Xi$ global poalrization in Au+Au collisions at 200 GeV. Decay parameter from PDG2020, $\alpha_{\Xi}$=-$\alpha_{\bar{\Xi}}$=-0.401, is used.
Measurements of the total and differential fiducial cross sections for the Z boson decaying into two neutrinos are presented at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were collected by the CMS detector in 2016 and correspond to an integrated luminosity of 35.9 fb$^{-1}$. In these measurements, events are selected containing an imbalance in transverse momentum and one or more energetic jets. The fiducial differential cross section is measured as a function of the Z boson transverse momentum. The results are combined with a previous measurement of charged-lepton decays of the Z boson.
The measured and predicted inclusive fiducial cross sections in fb. The experimental measurement includes both statistical and systematics uncertainties. The theoretical prediction includes both the QCD scale and PDF uncertainties.
Experimental uncertainties affecting transfer factors in the analysis that is used to estimate the W background in the signal region (SR). The number of W boson events are denoted as $W_{SR}$ for the SR and in analogy as $W_{\mu\nu}$ ($W_{e\nu}$) for the single-muon (single-electron) control region (CR).
Uncertainties assigned to the simulation based processes in SR and CRs.
A search for leptoquarks produced singly and in pairs in proton-proton collisions is presented. We consider the leptoquark (LQ) to be a scalar particle of charge -1/3$e$ coupling to a top quark plus a tau lepton ($\mathrm{t}\tau$) or a bottom quark plus a neutrino ($\mathrm{b}\nu$), or a vector particle of charge +2/3$e$, coupling to $\mathrm{t}\nu$ or $\mathrm{b}\tau$. These choices are motivated by models that can explain a series of anomalies observed in the measurement of B meson decays. In this analysis the signatures $\mathrm{t}\tau\nu\mathrm{b}$ and $\mathrm{t}\tau\nu$ are probed, using data recorded by the CMS experiment at the CERN LHC at $\sqrt{s} =$ 13 TeV and that correspond to an integrated luminosity of 137 fb$^{-1}$. These signatures have not been previously explored in a dedicated search. The data are found to be in agreement with the standard model prediction. Lower limits at 95% confidence level are set on the LQ mass in the range 0.98-1.73 TeV, depending on the LQ spin and its coupling $\lambda$ to a lepton and a quark, and assuming equal branching fractions for the two LQ decay modes considered. These are the most stringent constraints to date on the existence of leptoquarks in this scenario.
Pair leptoquark (LQ) total selection efficiency, accounting for both the decay branching fraction and the event selection, for events that pass the signal region requirements and any of the top quark or b jet categories defined in the search.
Single scalar leptoquark (LQs) total selection efficiency, accounting for both the decay branching fraction and the event selection, for events that pass the signal region requirements and any of the top quark or b jet categories defined in the search.
Single vector leptoquark (LQv) k = 0 total selection efficiency, accounting for both the decay branching fraction and the event selection, for events that pass the signal region requirements and any of the top quark or b jet categories defined in the search.
In 2015, the PHENIX collaboration has measured very forward ($\eta>6.8$) single-spin asymmetries of inclusive neutrons in transversely polarized proton-proton and proton-nucleus collisions at a center of mass energy of 200 GeV. A previous publication from this data set concentrated on the nuclear dependence of such asymmetries. In this measurement the explicit transverse-momentum dependence of inclusive neutron single spin asymmetries for proton-proton collisions is extracted using a bootstrapping-unfolding technique on the transverse momenta. This explicit transverse-momentum dependence will help improve the understanding of the mechanisms that create these asymmetries.
Measured and unfolded forward neutron single spin asymmetries using 3rd order polynomial parameterization in unfolding
Measured and unfolded forward neutron single spin asymmetries using a Power law parameterization in unfolding
Measured and unfolded forward neutron single spin asymmetries using an exponential parameterization in unfolding
We present a measurement of the transverse single-spin asymmetry for $\pi^0$ and $\eta$ mesons in $p^\uparrow$ $+$ $p$ collisions in the pseudorapidity range $|\eta|<0.35$ and at a center-of-mass energy of 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. In comparison with previous measurements in this kinematic region, these results have a factor of 3 smaller uncertainties. As hadrons, $\pi^0$ and $\eta$ mesons are sensitive to both initial- and final-state nonperturbative effects for a mix of parton flavors. Comparisons of the differences in their transverse single-spin asymmetries have the potential to disentangle the possible effects of strangeness, isospin, or mass. These results can constrain the twist-3 trigluon collinear correlation function as well as the gluon Sivers function.
Data from Figs. 2, 4, and 5 of the transverse single-spin asymmetry of neutral pions measured at $|\eta|<0.35$ in $p^\uparrow$$+$$p$ collisions at $\sqrt{s} = 200$ GeV. An additional scale uncertainty of 3.4\% due to the polarization uncertainty is not shown. The total $\sigma_{\rm syst}$ in the lowest $p_T$ bin includes an additional systematic uncertainty of $1.06\times10^{-4}$ from bunch shuffling.
Data from Figs. 3 and 4 of the transverse single-spin asymmetry of eta mesons measured at $|\eta|<0.35$ in $p^\uparrow$$+$$p$ collisions at $\sqrt{s} = 200$ GeV. An additional scale uncertainty of 3.4\% due to the polarization uncertainty is not shown. The total $\sigma_{\rm syst}$ in the lowest $p_T$ bin includes an additional systematic uncertainty of $6.20\times10^{-4}$ from bunch shuffling.
This paper presents a search for dark matter in the context of a two-Higgs-doublet model together with an additional pseudoscalar mediator, $a$, which decays into the dark-matter particles. Processes where the pseudoscalar mediator is produced in association with a single top quark in the 2HDM+$a$ model are explored for the first time at the LHC. Several final states which include either one or two charged leptons (electrons or muons) and a significant amount of missing transverse momentum are considered. The analysis is based on proton-proton collision data collected with the ATLAS experiment at $\sqrt{s} = 13$ TeV during LHC Run2 (2015-2018), corresponding to an integrated luminosity of 139 fb$^{-1}$. No significant excess above the Standard Model predictions is found. The results are expressed as 95% confidence-level limits on the parameters of the signal models considered.
Efficiencies of the DMt samples in the tW1L channel for all bins in the SR. The efficiency is defined as the number of weighted reconstructed events over the number of weighted TRUTH events in the SR. The maps include all samples in the $m_a - m_H$ plane with $tan\beta = 1$.
Acceptances on TRUTH level of the DMt samples in the tW1L channel for all bins in the SR. The acceptance is defined as the number of weighted TRUTH events in the SR over the number of expected events without any selections. The maps include all samples in the $m_a - m_H$ plane with $tan\beta = 1$.
Efficiencies of the DMt samples in the tW1L channel for all bins in the SR. The efficiency is defined as the number of weighted reconstructed events over the number of weighted TRUTH events in the SR. The maps include all samples in the $m_H - tan\beta$ plane with $m_a = 250~GeV$.
A search is performed for the rare decay W$^\pm\to\pi^\pm\gamma$ in proton-proton collisions at $\sqrt{s} =$ 13 TeV. Data corresponding to an on W integrated luminosity of 137 fb$^{-1}$ were collected during 2016 to 2018 with the CMS detector. This analysis exploits a novel search strategy based on W boson production in top quark pair events. An inclusive search for the W$^\pm\to\pi^\pm\gamma$ decay is not optimal at the LHC because of the high trigger thresholds. Instead, a trigger selection is exploited in which the W boson originating from one of the top quarks is used to tag the event in a leptonic decay. The W boson emerging from the other top quark is used to search for the W$^\pm\to\pi^\pm\gamma$ signature. Such decays are characterized by an isolated track pointing to a large energy deposit, and by an isolated photon of large transverse momentum. The presence of b quark jets reduces the background from the hadronization of light-flavor quarks and gluons. The W$^\pm\to\pi^\pm\gamma$ decay is not observed. An upper exclusion limit is set to this branching fraction, corresponding to 1.50 $\times$ 10$^{-5}$ at 95% confidence level, whereas the expected upper limit exclusion limit is 0.85 $^{+0.52}_{-0.29}$ $\times$ 10$^{-5}$.
The product of signal efficiency and acceptance per year and per lepton channel (muon or electron).
Expected and observed upper exclusion limits on the branching fraction of the decay of a W boson into a pion and a photon, using 2016 to 2018 data.