Incoherent J/$ψ$ photoproduction in heavy ion ultraperipheral collisions (UPCs) provides a sensitive probe of localized, fluctuating gluonic structures within heavy nuclei. This study reports the first measurement of the photon-nucleon center-of-mass energy ($W_{γ\mathrm{N}}$) dependence of this process in PbPb UPCs at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using 1.52 nb$^{-1}$ of data recorded by the CMS experiment. The measurement covers a wide $W_{γ\mathrm{N}}$ range of $\approx$ 40-400 GeV, probing gluons carrying a fraction $x$ of nucleon momentum down to an unexplored region of 6.5 $\times$ 10$^{-5}$. Compared to baseline predictions neglecting nuclear effects, the measured cross sections exhibit significantly greater suppression at lower $x$. Additionally, the ratio of incoherent to coherent photoproduction is found to be constant across the probed $W_{γ\mathrm{N}}$ and $x$ range, disfavoring the establishment of the black disk limit. This study provides critical insights into the $x$-dependent evolution of fluctuating gluonic structures within nuclei and calls for further advancements in theoretical models incorporating nuclear shadowing and gluon saturation.
The differential incoherent $\mathrm{J}/\psi$ photoproduction cross section as a function of $|y|$, in different neutron multiplicity classes.
The differential incoherent $\mathrm{J}/\psi$ photoproduction cross section as a function of $y$, in different neutron multiplicity classes.
The incoherent $\mathrm{J}/\psi$ photoproduction cross section as a function of photon-nuclear center-of-mass energy per nucleon $W_{\gamma \mathrm{N}}^{\mathrm{Pb}}$ or Bjorken $x$, measured in PbPb ultra-peripheral collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. The $W_{\gamma \mathrm{N}}^{\mathrm{Pb}}$ values used correspond to the center of each rapidity range. The theoretical uncertainties is due to the uncertainties in the photon flux.
In the standard model of particle physics, the masses of the carriers of the weak interaction, the W and Z bosons, are uniquely related. Physics beyond the standard model could change this relationship through the effects of quantum loops of virtual particles, thus making it of great importance to measure these masses with the highest possible precision. Although the mass of the Z boson is known to the remarkable precision of 22 parts per million (2.0 MeV), the W boson mass is known much less precisely, given the difficulty of the measurement. A global fit to electroweak data, used to predict the W boson mass in the standard model, yields an uncertainty of 6 MeV. Reaching a comparable experimental precision would be a sensitive and fundamental test of the standard model. Furthermore, a precision measurement of the W boson mass performed by the CDF Collaboration at the Fermilab Tevatron has challenged the standard model by significantly disagreeing with the prediction of the global electroweak fit and the average of other $m_\mathrm{W}$ measurements. We report the first W boson mass measurement by the CMS Collaboration at the CERN LHC, based on a data sample collected in 2016 at the proton-proton collision energy of 13 TeV. The W boson mass is measured using a large sample of W$\to\mu\nu$ events via a highly granular binned maximum likelihood fit to the kinematic properties of the muons produced in the W$^{+}$ and W$^{-}$ boson decays. The significant in situ constraints of theoretical inputs and their corresponding uncertainties, together with an accurate determination of the experimental effects, lead to a precise W boson mass measurement, $m_\mathrm{W} =$ 80$\,$360.2 $\pm$ 9.9 MeV, in agreement with the standard model prediction.
Postfit pulls, constraints, and impacts (both nominal and 'global') for all nuisance parameters in the W boson mass fit, sorted by the absolute value of the nominal impact.
Postfit pulls, constraints, and impacts (both nominal and 'global') for all nuisance parameters in the W boson mass fit (charge difference), sorted by the absolute value of the nominal impact.
Postfit pulls, constraints, and impacts (both nominal and 'global') for all nuisance parameters in the W-like Z boson mass fit, sorted by the absolute value of the nominal impact.
Differential cross-sections are measured for the production of four charged leptons in association with two jets. These measurements are sensitive to final states in which the jets are produced via the strong interaction as well as to the purely-electroweak vector boson scattering process. The analysis is performed using proton-proton collision data collected by ATLAS at $\sqrt{s}=13$ TeV and with an integrated luminosity of 140 fb$^{-1}$. The data are corrected for the effects of detector inefficiency and resolution and are compared to state-of-the-art Monte Carlo event generator predictions. The differential cross-sections are used to search for anomalous weak-boson self-interactions that are induced by dimension-six and dimension-eight operators in Standard Model effective field theory.
Predicted and observed yields as a function of $m_{jj}$ in the VBS-Enhanced region. Overflow events are included in the last bin of the distribution.
Predicted and observed yields as a function of $m_{jj}$ in the VBS-Suppressed region. Overflow events are included in the last bin of the distribution.
Predicted and observed yields as a function of $m_{4\ell}$ in the VBS-Enhanced region. Overflow events are included in the last bin of the distribution.
A precision measurement of the $Z$ boson production cross-section at $\sqrt{s} = 13$ TeV in the forward region is presented, using $pp$ collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb$^{-1}$. The production cross-section is measured using $Z\rightarrow\mu^+\mu^-$ events within the fiducial region defined as pseudorapidity $2.0<\eta<4.5$ and transverse momentum $p_{T}>20$ GeV/$c$ for both muons and dimuon invariant mass $60<M_{\mu\mu}<120$ GeV/$c^2$. The integrated cross-section is determined to be $\sigma (Z \rightarrow \mu^+ \mu^-)$ = 196.4 $\pm$ 0.2 $\pm$ 1.6 $\pm$ 3.9~pb, where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions within uncertainties.
Relative uncertainty for the integrated $Z -> \mu^{+} \mu^{-}$ cross-section measurement. The total uncertainty is the quadratic sum of uncertainties from statistical, systematic and luminosity contributions.
Final state radiation correction used in the $y^{Z}$ cross-section measurement. The first uncertainty is statistical and the second is systematic.
Final state radiation correction used in the $p_{T}^{Z}$ cross-section measurement. The first uncertainty is statistical and the second is systematic.
The production cross-sections of $J/\psi$ mesons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=5$ TeV are measured using a data sample corresponding to an integrated luminosity of $9.13\pm0.18~\text{pb}^{-1}$, collected by the LHCb experiment. The cross-sections are measured differentially as a function of transverse momentum, $p_{\text{T}}$, and rapidity, $y$, and separately for $J/\psi$ mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised $J/\psi$ mesons, the production cross-sections integrated over the kinematic range $0<p_{\text{T}}<20~\text{GeV}/c$ and $2.0<y<4.5$ are $8.154\pm0.010\pm0.283~\mu\text{b}$ for prompt $J/\psi$ mesons and $0.820\pm0.003\pm0.034~\mu\text{b}$ for nonprompt $J/\psi$ mesons, where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at $\sqrt{s}=8$ TeV and $13$ TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for $J/\psi$ mesons at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\text{NN}}}=5$ TeV. The results are compared with theoretical predictions.
Double-differential production cross-sections for prompt $J/\psi$ mesons in ($p_\text{T},y$) intervals. The first uncertainties are statistical, the second are correlated systematic uncertainties shared between intervals, the third are uncorrelated systematic uncertainties, and the last are correlated between $p_\text{T}$ intervals and uncorrelated between $y$ intervals.
Double-differential production cross-sections for nonprompt $J/\psi$ mesons in ($p_\text{T},y$) intervals. The first uncertainties are statistical, the second are correlated systematic uncertainties shared between intervals, the third are uncorrelated systematic uncertainties, and the last are correlated between $p_\text{T}$ intervals and uncorrelated between $y$ intervals.
Single-differential production cross-sections for prompt $J/\psi$ mesons as a function of $p_\text{T}$. The first uncertainties are statistical, the second are correlated systematic uncertainties shared between intervals, and the last are uncorrelated systematic uncertainties.
Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=8$ TeV. The analysis is performed in the $H \rightarrow \gamma\gamma$ decay channel using 20.3 fb$^{-1}$ of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The $pp\rightarrow H \rightarrow \gamma\gamma$ fiducial cross section is measured to be $43.2 \pm 9.4 (stat) {}^{+3.2}_{-2.9} (syst) \pm 1.2 (lumi)$ fb for a Higgs boson of mass 125.4 GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations.
Measured differential cross section with associated uncertainties as a function of transverse momentum of diphoton system. Each systematic uncertainty sources is fully uncorrelated with the other sources and fully correlated across bins, except for the background modelling systematics for which an uncorrelated treatment across bins is more appropriate.
Measured differential cross section with associated uncertainties as a function of absolute rapidity of diphoton system. Each systematic uncertainty sources is fully uncorrelated with the other sources and fully correlated across bins, except for the background modelling systematics for which an uncorrelated treatment across bins is more appropriate.
Measured differential cross section with associated uncertainties as a function of multiplicity of jets with transverse momentum pT(jet) > 30 GeV. Each systematic uncertainty sources is fully uncorrelated with the other sources and fully correlated across bins, except for the background modelling systematics for which an uncorrelated treatment across bins is more appropriate.
Measurements of differential production cross-sections of a $Z$ boson in association with $b$-jets in $pp$ collisions at $\sqrt{s}=7$ TeV are reported. The data analysed correspond to an integrated luminosity of 4.6 fb$^{-1}$ recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a $Z$ boson decaying into an electron or muon pair, and containing $b$-jets. For events with at least one $b$-jet, the cross-section is presented as a function of the $Z$ boson transverse momentum and rapidity, together with the inclusive $b$-jet cross-section as a function of $b$-jet transverse momentum, rapidity and angular separations between the $b$-jet and the $Z$ boson. For events with at least two $b$-jets, the cross-section is determined as a function of the invariant mass and angular separation of the two highest transverse momentum $b$-jets, and as a function of the $Z$ boson transverse momentum and rapidity. Results are compared to leading-order and next-to-leading-order perturbative QCD calculations.
Integrated $Z+\ge 1$ $b$-jet cross-section and the integrated inclusive $b$-jet cross-sections.
Breakdown of systematic uncertainties (in %) for the integrated $Z+\ge 1$ $b$-jet cross-section and the integrated inclusive $b$-jet cross-sections.
The inclusive $b$-jet cross-section $\sigma(Zb)\times N_{b\text{-jet}}$ as a function of $b$-jet $p_T$ together with the corresponding non-perturbative corrections.
Measurements of normalized differential cross-sections for top-quark pair production are presented as a~function of the top-quark transverse momentum, and of the mass, transverse momentum, and rapidity of the $t\bar{t}$ system, in proton--proton collisions at a~center-of-mass energy of $\sqrt{s}$ = 7 TeV. The dataset corresponds to an integrated luminosity of 4.6 fb$^{-1}$, recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Events are selected in the lepton+jets channel, requiring exactly one lepton and at least four jets with at least one of the jets tagged as originating from a~$b$-quark. The measured spectra are corrected for detector efficiency and resolution effects and are compared to several Monte Carlo simulations and theory calculations. The results are in fair agreement with the predictions in a~wide kinematic range. Nevertheless, data distributions are softer than predicted for higher values of the mass of the $t\bar{t}$ system and of the top-quark transverse momentum. The measurements can also discriminate among different sets of parton distribution functions.
Normalized differential cross-sections for the hadronically decaying top-quark PT. The cross-section in each bin is given as the integral of the normalized differential cross-section over the bin width, divided by the bin width. The calculation of the cross-sections in the last bins includes events falling outside of the bin edges, and the normalization is done within the quoted bin width. The full covariance matrice is provided in Table 5 below.
Normalized differential cross-sections for the mass of the ttbar system. The cross-section in each bin is given as the integral of the normalized differential cross-section over the bin width, divided by the bin width. The calculation of the cross-sections in the last bins includes events falling outside of the bin edges, and the normalization is done within the quoted bin width. The full covariance matrice is provided in Table 6 below.
Normalized differential cross-sections for the PT of the ttbar system. The cross-section in each bin is given as the integral of the normalized differential cross-section over the bin width, divided by the bin width. The calculation of the cross-sections in the last bins includes events falling outside of the bin edges, and the normalization is done within the quoted bin width. The full covariance matrice is provided in Table 7 below.
This article presents measurements of the $t$-channel single top-quark ($t$) and top-antiquark ($\bar{t}$) total production cross sections $\sigma(tq)$ and $\sigma(\bar{t}q)$, their ratio $R_{t}=\sigma(tq)/\sigma(\bar{t}q)$, and a measurement of the inclusive production cross section $\sigma(tq + \bar{t}q)$ in proton--proton collisions at $\sqrt{s} = 7$ TeV at the LHC. Differential cross sections for the $tq$ and $\bar{t}q$ processes are measured as a function of the transverse momentum and the absolute value of the rapidity of $t$ and $\bar{t}$, respectively. The analyzed data set was recorded with the ATLAS detector and corresponds to an integrated luminosity of 4.59 fb$^{-1}$. Selected events contain one charged lepton, large missing transverse momentum, and two or three jets. The cross sections are measured by performing a binned maximum-likelihood fit to the output distributions of neural networks. The resulting measurements are $\sigma(tq)= 46\pm 6\; \mathrm{pb}$, $\sigma(\bar{t}q)= 23 \pm 4\; \mathrm{pb}$, $R_{t}=2.04\pm 0.18$, and $\sigma(tq + \bar{t}q)= 68 \pm 8\; \mathrm{pb}$, consistent with the Standard Model expectation. The uncertainty on the measured cross sections is dominated by systematic uncertainties, while the uncertainty on $R_{t}$ is mainly statistical. Using the ratio of $\sigma(tq + \bar{t}q)$ to its theoretical prediction, and assuming that the top-quark-related CKM matrix elements obey the relation $|V_{tb}|\gg |V_{ts}|, |V_{td}|$, we determine $|V_{tb}|=1.02 \pm 0.07$.
Predicted and observed events yields for the 2-jet and 3-jet channels considered in this measurement. The multijet background is estimated using data-driven techniques (see Sec. VB); an uncertainty of $50\%$ is applied. All the other expectations are derived using theoretical cross sections and their uncertainties (see Secs. VA and VC in the paper).
Detailed list of the contribution of each source of uncertainty to the total uncertainty on the measured values of $\sigma(tq)$, $\sigma(\bar{t}q)$, $R_t$, and $\sigma(tq+\bar{t}q)$. The evaluation of the systematic uncertainties has a statistical uncertainty of $0.3\,\%$. Uncertainties contributing less than $1.0\,\%$ are marked with "$<1$" in the paper. To provide numerical values for this table in HEPdata, these uncertainties are approximated with $\pm 0.5\,\%$. This approximation is applied to all measurements for the following uncertainties$:$ JES statistical, JES physics modeling, JES mixed detector and modeling, JES close-by-jets, JES pileup, $b$-JES, jet vertex fraction, mistag efficiency and $W+\;$jets shape variation. For the measurement of $\sigma(tq)$ the approximation is applied in addition to the following uncertainties$:$ JES flavor response, $c$-tagging efficiency, $t\bar{t}$ generator + parton shower and $t\bar{t}$ ISR/FSR. For the measurement of $\sigma(\bar{t}q)$ the approximation is applied in addition to these uncertainties$:$ JES flavor response, $b/\bar{b}$ acceptance, and $t\bar{t}$ ISR/FSR. For the measurement of $R_t$ the approximation is applied in addition to these uncertainties$:$ JES detector, $b$-tagging efficiency, $c$-tagging efficiency, $b/\bar{b}$ acceptance and $tq$ scale variations. For the measurement of $\sigma(tq+\bar{t}q)$ the approximation is applied in addition to these uncertainties$:$ JES flavor response, $c$-tagging efficiency, $b/\bar{b}$ acceptance, $t\bar{t}$ generator + parton shower and $t\bar{t}$ ISR/FSR.
The cross sections for top-quark and top-antiquark production in the t-channel, together with the cross-section ratio.
A measurement is presented of the phi to K+K- production cross section at sqrt(s) = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 mub-1, collected with the ATLAS experiment at the LHC. Selection of phi(1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, pTphi, and rapidity, |yphi|, of the phi(1020) meson in the fiducial region 500 < pTphi< 1200 MeV, |yphi| < 0.8, kaon pTK> 230 MeV and kaon momentum pK< 800 MeV.The integrated phi(1020)-meson production cross section in this fiducial range is measured to be s(phi K+K-) = 570 pm 8 (stat) pm 66 (syst) pm 20 (lumi) mub.
The differential PHI(1020) meson production cross section measured in the fiducial region as a function of the PHI(1020) transverse momentum.
The differential PHI(1020) meson production cross section measured in the fiducial region as a function of the PHI(1020) rapidity.
The integrated PHI(1020) meson production cross section in the fiducial region.
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