The ratios of the production cross sections between the excited $\Upsilon$(2S) and $\Upsilon$(3S) mesons and the $\Upsilon$(1S) ground state, detected via their decay into two muons, are studied as a function of the number of charged particles in the event. The data are from proton-proton collisions at $\sqrt{s} =$ 7 TeV, corresponding to an integrated luminosity of 4.8 fb$^{-1}$, collected with the CMS detector at the LHC. Evidence of a decrease in these ratios as a function of the particle multiplicity is observed, more pronounced at low transverse momentum $p_\mathrm{T}^{\mu\mu}$. For $\Upsilon$(nS) mesons with $p_\mathrm{T}^{\mu\mu}$ $\gt$ 7 GeV, where most of the data were collected, the correlation with multiplicity is studied as a function of the underlying event transverse sphericity and the number of particles in a cone around the $\Upsilon$(nS) direction. The ratios are found to be multiplicity independent for jet-like events. The mean $p_\mathrm{T}^{\mu\mu}$ values for the $\Upsilon$(nS) states as a function of particle multiplicity are also measured and found to grow more steeply as their mass increases.
The measured ratios $\Upsilon(2$S$)\,/\,\Upsilon(1$S$)$ and $\Upsilon(3$S$)\,/\,\Upsilon(1$S$)$ with $p_T(\Upsilon(n$S$))>7\,GeV$ and $|y(\Upsilon(n$S$))| < 1.2$, as a function of track multiplicity $N_{track}$
The measured ratios $\Upsilon(2$S$)\,/\,\Upsilon(1$S$)$ and $\Upsilon(3$S$)\,/\,\Upsilon(1$S$)$ with $p_T(\Upsilon(n$S$))>0\,GeV$ and $|y(\Upsilon(n$S$))| < 1.93$, as a function of track multiplicity $N_{track}$.
Mean $p_T$ values of the $\Upsilon(1$S$)$, $\Upsilon(2$S$)$, and $\Upsilon(3S)$ states with $p_T\,>\,7\,GeV$ and $|y|\,<\,1.2$ as a function of track multiplicity $N_{track}$
Ratios of cross sections, $\sigma$(Z+c jets)/$\sigma$(Z+jets), $\sigma$(Z+b jets)/$\sigma$(Z+jets), and $\sigma$(Z+c jets)/$\sigma$(Z+b jets) in the associated production of a Z boson with at least one charm or bottom quark jet are measured in proton-proton collisions at $\sqrt{s}=$ 13 TeV. The data sample, collected by the CMS experiment at the CERN LHC, corresponds to an integrated luminosity of 35.9 fb$^{-1}$, with a fiducial volume of $p_\mathrm{T}>$ 30 GeV and $|\eta|<$ 2.4 for the jets, where $p_\mathrm{T}$ and $\eta$ represent transverse momentum and pseudorapidity, respectively. The Z boson candidates come from leptonic decays into electrons or muons with $p_\mathrm{T}>$ 25 GeV and $|\eta|<$ 2.4, and the dilepton mass satisfies 71 $\lt m_\mathrm{Z}\lt$ 111 GeV. The measured values are $\sigma$(Z+c jets)/$\sigma$(Z+jets) = 0.102 $\pm$ 0.002 $\pm$ 0.009, $\sigma$(Z+b jets)/$\sigma$(Z+jets) = 0.0633 $\pm$ 0.0004 $\pm$ 0.0015, and $\sigma$(Z+c jets)/$\sigma$(Z+b jets) = 1.62 $\pm$ 0.03 $\pm$ 0.15. Results on the inclusive and differential cross section ratios as functions of jet and Z boson transverse momentum are compared with predictions from leading and next-to-leading order perturbative quantum chromodynamics calculations. These are the first measurements of the cross section ratios at 13 TeV, and the measurement precision is better than that of the current theoretical predictions.
Unfolded R(c/j) cross section ratio versus jet transverse momentum
Unfolded R(c/j) cross section ratio versus Z boson transverse momentum
Unfolded R(b/j) cross section ratio versus jet transverse momentum
The cross section of top quark pair production is measured in the $\mathrm{t\bar{t}}\to (\ell\nu_{\ell})(\tau_\mathrm{h}\nu_{\tau})\mathrm{b\bar{b}}$ final state, where $\tau_\mathrm{h}$ refers to the hadronic decays of the $\tau$ lepton, and $\ell$ is either an electron or a muon. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ collected in proton-proton collisions at $\sqrt{s}=$ 13 TeV with the CMS detector. The measured cross section is $\sigma_{\mathrm{t\bar{t}}} =$ 781 $\pm$ 7 (stat) $\pm$ 62 (syst) $\pm$ 20 (lum) pb, and the ratio of the partial width $\Gamma($t$\to\tau\nu_{\tau}$b) to the total decay width of the top quark is measured to be 0.1050 $\pm$ 0.0009 (stat) $\pm$ 0.0071 (syst). This is the first measurement of the $\mathrm{t\bar{t}}$ production cross section in proton-proton collisions at $\sqrt{s}=$ 13 TeV that explicitly includes $\tau$ leptons. The ratio of the cross sections in the $\ell\tau_\mathrm{h}$ and $\ell\ell$ final states yields a value $R_{\ell\tau_\mathrm{h}/\ell\ell}=$ 0.973 $\pm$ 0.009 (stat) $\pm$ 0.066 (syst), consistent with lepton universality.
The measured inclusive top quark pair production cross section in the dilepton final state with one tau lepton.
The ratio between top quark production cross sections measured in lepton-tau and light dilepton final states.
The ratio of the partial width to the total decay width of the top quark.
A study is presented of anomalous HVV interactions of the Higgs boson, including its $CP$ properties. The study uses Higgs boson candidates produced mainly in vector boson fusion and gluon fusion that subsequently decay to a pair of $\tau$ leptons. The data were recorded by the CMS experiment at the LHC in 2016 at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 35.9 fb$^{-1}$. A matrix element technique is employed for the analysis of anomalous interactions. The results are combined with those from the H $\to 4\ell$ decay channel presented earlier, yielding the most stringent constraints on anomalous Higgs boson couplings to electroweak vector bosons expressed as effective cross section fractions and phases: the $CP$-violating parameter $f_{a3}\cos(\phi_{a3})$ $=$ $(0.00 \pm 0.27) \times 10^{-3}$ and the $CP$-conserving parameters $f_{a2}\cos(\phi_{a2})$ $=$ $(0.08 ^{+1.04}_{-0.21}) \times 10^{-3}$, $f_{\Lambda1}\cos(\phi_{\Lambda1})$ $=$ $(0.00 ^{+0.53}_{-0.09}) \times 10^{-3}$, and $f_{\Lambda1}^{\mathrm{Z}\gamma}\cos(\phi_{\Lambda1}^{\mathrm{Z}\gamma})$ $=$ $(0.0 ^{+1.1}_{-1.3}) \times 10^{-3}$. The current dataset does not allow for precise constraints on $CP$ properties in the gluon fusion process. The results are consistent with standard model expectations.
Observed and expected likelihood scans of $f_{a3}\cos\phi_{a3}$. See Section 4 of the paper for more details.
Observed and expected likelihood scans of $f_{a2}\cos\phi_{a2}$. See Section 4 of the paper for more details.
Observed and expected likelihood scans of $f_{\Lambda1}\cos\phi_{\Lambda1}$. See Section 4 of the paper for more details.
This Letter describes a search for Higgs boson pair production using the combined results from four final states: bb$\gamma\gamma$, bb$\tau\tau$, bbbb, and bbVV, where V represents a W or Z boson. The search is performed using data collected in 2016 by the CMS experiment from LHC proton-proton collisions at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Limits are set on the Higgs boson pair production cross section. A 95% confidence level observed (expected) upper limit on the nonresonant production cross section is set at 22.2 (12.8) times the standard model value. A search for narrow resonances decaying to Higgs boson pairs is also performed in the mass range 250-3000 GeV. No evidence for a signal is observed, and upper limits are set on the resonance production cross section.
Expected and observed 95\% \CL exclusion limits on the HH production signal strength for the different channels and their combination.
Expected and observed 95\% \CL exclusion limits on the HH production cross section as a function of the k_lambda parameter.
Expected and observed 95\% \CL exclusion limits on the production of a narrow, spin zero resonance (X) decaying into a pair of Higgs bosons.
A study of the associated production of a Z boson and a charm quark jet (Z + c), and a comparison to production with a b quark jet (Z + b), in pp collisions at a centre-of-mass energy of 8 TeV are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb$^{-1}$, collected with the CMS detector at the CERN LHC. The Z boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of c or b flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with $p_{\rm T}^{\ell} > $ 20 GeV, ${|\eta^{\ell}|} < $ 2.1, 71 $ < m_{\ell\ell} < $ 111 GeV, and heavy flavour jets with $p_{\rm T}^{{\rm jet}} > $ 25 GeV and ${|\eta^{{\rm jet}}|} < $ 2.5. The Z + c production cross section is measured to be $\sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{c} + \mathrm{X}) {\cal B}(\mathrm{Z} \rightarrow \ell^+\ell^-) = $ 8.8 $ \pm $ 0.5 (stat) $ \pm $ 0.6 (syst) pb. The ratio of the Z + c and Z + b production cross sections is measured to be $\sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{c} + \mathrm{X}) / \sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{b} + \mathrm{X}) = $ 2.0 $ \pm $ 0.2 (stat) $ \pm $ 0.2 (syst). The Z + c production cross section and the cross section ratio are also measured as a function of the transverse momentum of the Z boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.
Signal yields N(Z+c) and N(Z+b), efficiency*acceptance correction factors C(Z+c) and C(Z+b), cross section sigma(Z+c)B and cross section ratios sigma(Z+c)/sigma(Z+b) in the three categories (semileptonic, D+-, D*) and in the two Z boson decay channels (e+e-, mu+mu-). The factors that correct the acceptance and selection inefficiencies are also given. They include the relevant branching fraction for the corresponding channel. All uncertainties quoted in the table are statistical, except for those of the measured cross sections and cross section ratios where the first uncertainty is statistical and the second is the estimated systematic uncertainty
Z+c and Z+b signal yields, differential cross section dsigma(Z+c)/dpTZ times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTZ for three ranges of the transverse momentum of the Z boson in the semileptonic mode
Z+c and Z+b signal yields, differential cross section dsigma(Z+c)/dpTZ times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTZ for three ranges of the transverse momentum of the jet in the semileptonic mode
An invariant differential cross section measurement of inclusive $\pi^{0}$ and $\eta$ meson production at mid-rapidity in pp collisions at $\sqrt{s}=8$ TeV was carried out by the ALICE experiment at the LHC. The spectra of $\pi^{0}$ and $\eta$ mesons were measured in transverse momentum ranges of $0.3<p_{\rm T}<35$ GeV/$c$ and $0.5<p_{\rm T}<35$ GeV/$c$, respectively. Next-to-leading order perturbative QCD calculations using fragmentation functions DSS14 for the $\pi^{0}$ and AESSS for the $\eta$ overestimate the cross sections of both neutral mesons, although such calculations agree with the measured $\eta/\pi^{0}$ ratio within uncertainties. The results were also compared with PYTHIA~8.2 predictions for which the Monash~2013 tune yields the best agreement with the measured neutral meson spectra. The measurements confirm a universal behavior of the $\eta/\pi^{0}$ ratio seen for NA27, PHENIX and ALICE data for pp collisions from $\sqrt{s}=27.5$ GeV to $\sqrt{s}=8$ TeV within experimental uncertainties. A relation between the $\pi^{0}$ and $\eta$ production cross sections for pp collisions at $\sqrt{s}=8$ TeV is given by $m_{\rm T}$ scaling for $p_{\rm T}>3.5$ GeV/$c$. However, a deviation from this empirical scaling rule is observed for transverse momenta below $p_{\rm T}<3.5$ GeV/$c$ in the $\eta/\pi^0$ ratio with a significance of $6.2\sigma$.
Invariant differential cross section of $\pi^0$ produced in inelastic pp collisions at center of mass energy 8 TeV, the uncertainty of $\sigma_{MB}$ of 2.6% is not included in the systematic error.
Invariant differential cross section of $\eta$ produced in inelastic pp collisions at center of mass energy 8 TeV, the uncertainty of $\sigma_{MB}$ of 2.6% is not included in the systematic error.
Integrated yields of $\pi^{0}$ mesons produced in inelastic pp collisions at center of mass energies of 2.76 and 8 TeV. The uncertainty of $\sigma_{MB}$ of $^{+3.9\%}_{-6.4\%}(model)\pm2.0(lumi)$% for $\sqrt{s}=2.76$ TeV and $\pm2.3$% for 8 TeV is not included in the systematic error.
A search is performed for anomalous interactions of the recently discovered Higgs boson using matrix element techniques with the information from its decay to four leptons and from associated Higgs boson production with two quark jets in either vector boson fusion or associated production with a vector boson. The data were recorded by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 38.6 inverse femtobarns. These data are combined with the data collected at center-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.7 inverse femtobarns, respectively. All observations are consistent with the expectations for the standard model Higgs boson.
Observed and expected likelihood scans $f_{a3}\cos\phi_{a3}$. See Section 2 of the paper for more details.
Observed and expected likelihood scans $f_{a2}\cos\phi_{a2}$. See Section 2 of the paper for more details.
Observed and expected likelihood scans $f_{\Lambda1}\cos\phi_{\Lambda1}$. See Section 2 of the paper for more details.
The invariant differential cross sections for inclusive $\pi^{0}$ and $\eta$ mesons at midrapidity were measured in pp collisions at $\sqrt{s}=2.76$ TeV for transverse momenta $0.4<p_{\rm T}<40$ GeV/$c$ and $0.6<p_{\rm T}<20$ GeV/$c$, respectively, using the ALICE detector. This large range in $p_{\rm T}$ was achieved by combining various analysis techniques and different triggers involving the electromagnetic calorimeter (EMCal). In particular, a new single-cluster, shower-shape based method was developed for the identification of high-$p_{\rm T}$ neutral pions, which exploits that the showers originating from their decay photons overlap in the EMCal. The measured cross sections are found to exhibit a similar power-law behavior with an exponent of about $6.3$. Next-to-leading-order perturbative QCD calculations differ from the measured cross sections by about $30$% for the $\pi^0$, and between $30$-$50$% for the $\eta$ meson, while generator-level simulations with PYTHIA 8.2 describe the data to better than $10$-$30$%, except at $p_{\rm T}<1$ GeV/$c$. The new data can therefore be used to further improve the theoretical description of $\pi^{0}$ and $\eta$ meson production.
Invariant differential yields of $\pi^0$ produced in inelastic pp collisions at center-of-mass energy 2.76 TeV, the normalization uncertainties of 5.7% are not included in the systematic error.
Invariant differential yields of $\eta$ produced in inelastic pp collisions at center-of-mass energy 2.76 TeV, the normalization uncertainties of 5.7% are not included in the systematic error.
Invariant differential cross section of $\pi^0$ produced in inelastic pp collisions at center-of-mass energy 2.76 TeV, the uncertainty of $\sigma_{MB}$ of 2.5% is not included in the systematic error.
The production cross sections of the prompt charmed mesons ${\rm D^0}$, ${\rm D^+}$, ${\rm D^{*+}}$ and ${\rm D_s^+}$ were measured at mid-rapidity in proton-proton collisions at a centre-of-mass energy $\sqrt{s}=7$ TeV with the ALICE detector at the Large Hadron Collider (LHC). D mesons were reconstructed from their decays ${\rm D}^0 \to {\rm K}^-\pi^+$, ${\rm D}^+\to {\rm K}^-\pi^+\pi^+$, ${\rm D}^{*+} \to {\rm D}^0 \pi^+$, ${\rm D_s^{+}\to \phi\pi^+\to K^-K^+\pi^+}$, and their charge conjugates. With respect to previous measurements in the same rapidity region, the coverage in transverse momentum ($p_{\rm T}$) is extended and the uncertainties are reduced by a factor of about two. The accuracy on the estimated total $\rm c\overline c$ production cross section is likewise improved. The measured $p_{\rm T}$-differential cross sections are compared with the results of three perturbative QCD calculations.
$p_{\rm T}$-differential cross section of prompt $\rm{D}^{0}$ mesons in pp collisions at $\sqrt{s_{\rm{NN}}}$=7 TeV in the rapidity interval $|y|$<0.5. Branching ratio of $\rm{D}^{0}\rightarrow K\pi$ : 0.0393.
$p_{\rm T}$-differential cross section of prompt $\rm{D^{+}}$ mesons in pp collisions at $\sqrt{s_{\rm{NN}}}$=7 TeV in the rapidity interval $|y|$<0.5. Branching ratio of $\rm D^{+-}\rightarrow K{\rm{\pi}}{\rm{\pi}}$ : 0.0946.
$p_{\rm T}$-differential cross section of prompt $\rm D^{*}$ mesons in pp collisions at $\sqrt{s_{\rm{NN}}}$=7 TeV in the rapidity interval $|y|$<0.5. Branching ratio of $\rm{D}^{*+}\rightarrow \rm{D}^{0}\pi\rightarrow K\pi\pi$ : 0.0266.
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