Within the theory of supersymmetry, the lightest neutralino is a dark matter candidate and is often assumed to be the lightest supersymmetric particle (LSP) as well. If the neutral wino or higgsino is dark matter, the upper limit of the LSP mass is determined by the observed relic density of dark matter. If the LSP is a nearly-pure neutral state of the wino or higgsino, the lightest chargino state is expected to have a significant lifetime due to a tiny mass difference between the LSP and the chargino. This article presents discovery potential of the 100 TeV future circular hadron collider (FCC) for the wino and higgsino dark matter using a disappearing-track signature. The search strategy to extend the discovery reach to the thermal limits of wino/higgsino dark matter is discussed with detailed studies on the background rate and the reference design of the FCC-hadron detector under possible running scenarios of the FCC-hadron machine. A proposal of modifying the detector layout and several ideas to improve the sensitivity further are also discussed.
One of three barrel inner-tracker layouts considered in this study; the default layout $\#$1. The contour drawn behind the layouts shows the number of chargino decays in 3 TeV wino signal events with 30 ab$^{-1}$ at a given position. The analysis considers the region $|\eta|<1$, denoted by the dotted lines.
Leading jet $p_{T}$ distributions after removing events containing isolated leptons with 30 ab$^{-1}$ at $\sqrt{s}=100$ TeV. The SM backgrounds from $W/Z$+jets and top production processes are shown as filled histograms. Also shown as dashed (dotted) line is the 3 (1) TeV wino (higgsino) signal scaled up by a factor 1000.
$E_{\text{T}}^{\text{miss}}$ distributions after removing events containing isolated leptons with 30 ab$^{-1}$ at $\sqrt{s}=100$ TeV. The SM backgrounds from $W/Z$+jets and top production processes are shown as filled histograms. Also shown as dashed (dotted) line is the 3 (1) TeV wino (higgsino) signal scaled up by a factor 1000.
A search for dark matter produced in association with top quarks in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. The data set used corresponds to an integrated luminosity of 35.9 fb$^{-1}$ recorded with the CMS detector at the LHC. Whereas previous searches for neutral scalar or pseudoscalar mediators considered dark matter production in association with a top quark pair only, this analysis also includes production modes with a single top quark. The results are derived from the combination of multiple selection categories that are defined to target either the single top quark or the top quark pair signature. No significant deviations with respect to the standard model predictions are observed. The results are interpreted in the context of a simplified model in which a scalar or pseudoscalar mediator particle couples to a top quark and subsequently decays into dark matter particles. Scalar and pseudoscalar mediator particles with masses below 290 and 300 GeV, respectively, are excluded at 95 % confidence level, assuming a dark matter particle mass of 1 GeV and mediator couplings to fermions and dark matter particles equal to unity.
Background-only post-fit $p_{T}^{miss}$ distributions for the CRs of the SL selection. The total theory signal (t/t+DM and tt+DM summed together) is negligible and therefore is not shown. The last bin contains overflow events.
Background-only post-fit $p_{T}^{miss}$ distributions for the CRs of the SL selection. The total theory signal (t/t+DM and tt+DM summed together) is negligible and therefore is not shown. The last bin contains overflow events.
Background-only post-fit $p_{T}^{miss}$ distributions for the CRs of the SL selection. The total theory signal (t/t+DM and tt+DM summed together) is negligible and therefore is not shown. The last bin contains overflow events.
We present two-particle $p_{\rm t}$ correlations as a function of event centrality for Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV at the Relativistic Heavy Ion Collider using the STAR detector. These results are compared to previous measurements from CERES at the Super Proton Synchrotron and from ALICE at the Large Hadron Collider. The data are compared with UrQMD model calculations and with a model based on a Boltzmann-Langevin approach incorporating effects from thermalization. The relative dynamical correlations for Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV show a power law dependence on the number of participant nucleons and agree with the results for Pb+Pb collisions at $\sqrt{s_{\rm NN}} = 2.76~ {\rm TeV}$ from ALICE. As the collision energy is lowered from $\sqrt{s_{\rm NN}}$ = 200 GeV to 7.7 GeV, the centrality dependence of the relative dynamical correlations departs from the power law behavior observed at the higher collision energies. In central collisions, the relative dynamical correlations increase with collision energy up to $\sqrt{s_{\rm NN}}$ = 200 GeV in contrast to previous measurements that showed little dependence on the collision energy.
'The relative dynamical correlation as a function of $N_{part}$'
'The relative dynamical correlation as a function of $N_{part}$'
'The relative dynamical correlation as a function of $N_{part}$'
A search for charged lepton flavor violating decays $\tau\to3\mu$ has been performed using proton-proton collisions with a center-of-mass energy of 13 TeV. The analysis uses the data set collected by the CMS detector in 2016, corresponding to an integrated luminosity of 33 fb$^{-1}$, and exploits $\tau$ leptons produced in D and B meson decays. No signal is observed, and an upper limit of $8.8\times 10^{-8}$ is set at the $90\%$ confidence level on the branching fraction of the $\tau$ lepton to three muons.
Expected and observed 90% CL upper limits on the branching fraction of the tau lepton to 3 muons.
A study of the $\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \bar{\Lambda} \mathrm{p}$ decay is reported, using proton-proton collision data collected at $\sqrt{s}= 8~\mathrm{TeV}$ by the CMS experiment at the LHC, corresponding to an integrated luminosity of $19.6~\mathrm{fb}^{-1}$. The ratio of branching fractions $\frac{{\cal B}(\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \bar{\Lambda} \mathrm{p})}{{\cal B}(\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \mathrm{K}^{*+})}$ is measured to be $1.054\pm0.057~\text{(stat)} \pm0.028~\text{(syst)}\pm0.011({\cal B})\%$, where the first uncertainty is statistical, the second is systematic, and the third reflects the uncertainties in the world-average branching fractions. The invariant mass distributions of $\mathrm{J}/\psi \bar{\Lambda}$, $\mathrm{J}/\psi \mathrm{p}$, and $\bar{\Lambda} \mathrm{p}$ systems produced in the $\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \bar{\Lambda} \mathrm{p}$ decay are investigated and found to be inconsistent with the pure phase space hypothesis. The analysis is extended by using a model-independent angular amplitude analysis, which shows that the inclusion of contributions from excited kaons in the $\bar{\Lambda} \mathrm{p}$ system does improve the description of the observed invariant mass distributions.
The measured ratio of branching fractios
The transverse momentum (pT) spectra of prompt D+ s mesons and charge conjugates are measured in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair using the CMS detector at the LHC. The measurement is performed through the D+ s !fp+ !K+Kp+ decay channels with the D+ s rapidity range jyj < 1.0. The D+ s production in the pT range from 2 (6) GeV/c to 40 GeV/c in pp (PbPb) collisions is measured. Suppression of the D+ s nuclear modification factor (RAA) in PbPb collisions suggests a strong interaction between charm quarks and the quarkgluon plasma. The double ratio of prompt D+ s to prompt D0 production in pp and PbPb is consistent with a PHSD model calculation and consistent with unity, which indicates that strange charm meson enhancement in PbPb collisions is not significant in the measured D+ s pT interval.
$p_T$ differential cross section of $D^+_s$ s in pp and PbPb at 5.02 TeV. The $p_T$-differential cross section of $D^+_s$ in pp collisions and $p_T$-differential corrected yield of $D^+_s$ mesons scaled by T$_\text{AA}$ in PbPb collisions are shown.
The ratio between $p_T$-differential cross section of $D^+_s$ in pp collisions and $p_T$-differential corrected yield of $D^+_s$ mesons scaled by T$_\text{AA}$ in PbPb collisions over PYTHIA8 are shown.
The nuclear modification factor (R$_\text{AA}$) of $D^+_s$.
Results are reported for the ${\rm B_s^0}\to\mu^+\mu^-$ branching fraction and effective lifetime and from a search for the decay ${\rm B^0}\to\mu^+\mu^-$. The analysis uses a data sample of proton-proton collisions accumulated by the CMS experiment in 2011, 2012, and 2016, with center-of-mass energies (integrated luminosities) of 7 TeV (5 fb$^{-1}$), 8 TeV (20 fb$^{-1}$), and 13 TeV (36 fb$^{-1}$). The branching fractions are determined by measuring efficiency-corrected event yields relative to ${\rm B^+}\to{\rm J}/\psi {\rm K^+}$ decays (with ${\rm J}/\psi\to\mu^+\mu^-$), which results in the cancellation of many of the systematic uncertainties. The decay ${\rm B_s^0}\to\mu^+\mu^-$ is observed with a branching fraction of ${\cal B}({\rm B_s^0}\to\mu^+\mu^-) = {[2.9^{+0.7}_{-0.6}\,(\text{exp})\pm{0.2}\,(\text{frag})]\times10^{-9}}$, where frag refers to the uncertainty in the ratio $f_s/f_u$ of the ${\rm B_s^0}$ and the ${\rm B^+}$ fragmentation functions, corresponding to a significance of 5.6 standard deviations. No significant excess is observed for the decay ${\rm B^0}\to\mu^+\mu^-$, and the upper limit ${\cal B}({\rm B^0}\to\mu^+\mu^-) < {3.6\times10^{-10}}$ is obtained at $95\%$ confidence level. These measured branching fractions are consistent with standard model predictions, and they supersede previous results from CMS based on the 2011 and 2012 data only. Finally, the ${\rm B_s^0}\to\mu^+\mu^-$ effective lifetime is measured, for the first time in CMS, and is found to be $\tau_{\mu^+\mu^-} = {1.70^{+0.61}_{-0.44}}$ ps.
Branching fraction upper limit for $B^{0}\rightarrow \mu^{+}\mu^{-}$
Summary of the systematic uncertainty sources.
Summary of the fitted yields for $B_{s}^{0}\rightarrow \mu^{+}\mu^{-}$ for all 14 categories of the 3D UML branching fraction fit.
A search for nonresonant excesses in the invariant mass spectra of electron and muon pairs is presented. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the CMS experiment in 2016, corresponding to a total integrated luminosity of 36 fb$^{-1}$. No significant deviation from the standard model is observed. Limits are set at 95% confidence level on energy scales for two general classes of nonresonant models. For a class of fermion contact interaction models, lower limits ranging from 20 to 32 TeV are set on the characteristic compositeness scale $\Lambda$. For the Arkani-Hamed, Dimopoulos, and Dvali model of large extra dimensions, the first results in the dilepton final state at 13 TeV are reported, and values of the ultraviolet cutoff parameter $\Lambda_\mathrm{T}$ below 6.9 TeV are excluded. A combination with recent CMS diphoton results improves this exclusion to $\Lambda_\mathrm{T}$ below 7.7 TeV, providing the most sensitive limits to date in nonhadronic final states.
Electron pair invariant mass spectra for the combined barrel-barrel and barrel-endcap event categories. Example model predictions are given for CI. The lower panel shows the relative difference between the data and predicted background. The gray band gives the fractional uncertainty (statistical and systematic) in the prediction.
Muon pair invariant mass spectra for the combined barrel-barrel and barrel-endcap event categories. Example model predictions are given for the ADD model. The lower panel shows the relative difference between the data and predicted background. The gray band gives the fractional uncertainty (statistical and systematic) in the prediction.
Dilepton exclusion limits at 95% CL on the CI scale (Lambda) for the six CI models considered for the electron channel. The limits are obtained for m > 400(2200) GeV in the case of constructive (destructive) interference.
A top quark mass measurement is performed using 35.9 fb$^{-1}$ of LHC proton-proton collision data collected with the CMS detector at $\sqrt{s} =$ 13 TeV. The measurement uses the $\mathrm{t\overline{t}}$ all-jets final state. A kinematic fit is performed to reconstruct the decay of the $\mathrm{t\overline{t}}$ system and suppress the multijet background. Using the ideogram method, the top quark mass ($m_\mathrm{t}$) is determined, simultaneously constraining an additional jet energy scale factor (JSF). The resulting value of $m_\mathrm{t}$ = 172.34 $\pm$ 0.20 (stat+JSF) $\pm$ 0.70 (syst) GeV is in good agreement with previous measurements. In addition, a combined measurement that uses the $\mathrm{t\overline{t}}$ lepton+jets and all-jets final states is presented, using the same mass extraction method, and provides an $m_\mathrm{t}$ measurement of 172.26 $\pm$ 0.07 (stat+JSF) $\pm$ 0.61 (syst) GeV. This is the first combined $m_\mathrm{t}$ extraction from the lepton+jets and all-jets channels through a single likelihood function.
Measured top quark mass $m_{t}$
Measurements of the differential cross section for the Drell-Yan process, based on proton-proton collision data at a centre-of-mass energy of 13 TeV, collected by the CMS experiment, are presented. The data correspond to an integrated luminosity of 2.8 (2.3) fb$^{-1}$ in the dimuon (dielectron) channel. The total and fiducial cross section measurements are presented as a function of dilepton invariant mass in the range 15 to 3000 GeV, and compared with the perturbative predictions of the standard model. The measured differential cross sections are in good agreement with the theoretical calculations.
Summary of the systematic uncertainties (%) for the $ d\sigma / d{m}$ (pb/GeV) measurement in the dimuon channel. The column labelled "Total" corresponds to the quadratic sum of all the experimental sources, except for that Acceptance+PDF.
Summary of the systematic uncertainties (%) for the $ d\sigma / d{m}$ (pb/GeV) measurement in the dielectron channel. The column labelled "Total" corresponds to the quadratic sum of all the experimental sources, except for that Acceptance+PDF.
Summary of the measured values of $ d\sigma / d{m}$ (pb/GeV) in the dimuon channel with the statistical ($\delta_{\text{stat}}$), experimental ($\delta_{\text{exp}}$) and theoretical ($\delta_{\text{theo}}$) uncertainties, respectively. Here, $\delta_{\text{tot}}$ is the quadratic sum of the three components.