An overview of recent results on electroweak precision measurements from the CMS Collaboration is presented. Studies of the weak boson differential transverse momentum spectra, Z boson angular coefficients, forward-backward asymmetry of Drell-Yan lepton pairs and charge asymmetry of W boson production are made in comparison to the state-of-the-art Monte Carlo generators and theoretical predictions. The results show a good agreement with the Standard Model. As a proof of principle for future W mass measurements, a W-like analysis of the Z boson mass is performed.
Searches for direct electroweak production of charginos and neutralinos in signatures with two light leptons of the same charge and with three or more leptons including up to two hadronically decaying τ leptons are presented . The full 2016 dataset of pp collisions recorded by CMS at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 35.9 /fb. The observed event rates are in agreement with expectations from the standard model. These results probe charginos and neutralinos with masses up to values between 225 and 1150 GeV, depending on the model parameters a…
Measurements of the hadronic activity and the electroweak production in events with a Z boson and two jets in proton-proton collisions with the CMS experiment
本文介绍了在CERN大型强子对撞机上利用CMS实验观测到的$\sqrt{s} = 8$ TeV pp碰撞中两喷流产生Z玻色子的电弱过程，所用数据样本的积分亮度为19.7 fb $^{-1}$ .结合μ子和电子通道的截面测量与理论预期一致。还测量了选定的Z+两个喷注事件的辐射图，以及喷注之间快度区间的强子活动。这些结果是相当重要的矢量玻色子融合过程的更一般的研究，相关的希格斯玻色子搜索和测量的电弱规范耦合和矢量玻色子散射。
Recent analyses of top quark production in association with vector bosons are summarized, representing the most precise inclusive and differential cross section measurements of these processes to date. Proton-proton collision data at a center-of-mass energy of $\sqrt{s}=13$ TeV, recorded by the ATLAS and CMS detectors at the LHC are analyzed, corresponding to an integrated luminosity of up to 139 fb$^{-1}$ for each experiment. Comparisons with theory calculations are performed and overall good agreement with standard model predictions are obtained.
The results from a search for chargino-neutralino or chargino pair production via electroweak interactions are summarized. The results are based on a sample of $\sqrt{s}=13~\mathrm{TeV}$ proton-proton collisions from the LHC, recorded with the CMS detector~\cite{cms} and corresponding to an integrated luminosity of $137~\mathrm{fb}^{-1}$. The search considers final states with large missing transverse momentum and pairs of hadronically decaying bosons WW, WZ, and WH, which are identified using novel algorithms. No significant excess of events is observed relative to the expectation from the st…
We report on a precision measurement of the effective weak mixing angle using the forward-backward asymmetry of Drell-Yan ($ee$ and $μμ$) events in pp collisions at $\sqrt{s}=8~\mathrm{TeV}$ at CMS. The data sample corresponds to an integrated luminosity of $18.8~\mathrm{fb}^{-1}$ and $19.6~\mathrm{fb}^{-1}$ for muon and electron channels, respectively. The sample consists of 8.2 million dimuon and 4.9 million dielectron events. With new analysis techniques and large samples the statistical and systematic uncertainties are reduced by a factor of two compared to previous measurements at the LHC…
In this contribution, I have outlined recent precision measurements of the standard model (SM) multiboson production at CMS. A study of diboson production at 5 TeV constitutes an important probe of the SM at a new energy, and the data favour NNLO predictions obtained by MATRIX. A study of WZ production at 13 TeV constitutes the most comprehensive study of WZ production to date, containing inclusive and differential cross section measurements, charge asymmetry measurements, constraints on the LHC proton parton distribution functions, and constraints on anomalous values of the WWZ trilinear gaug…
A search for new physics in central exclusive production using the missing mass technique with the CMS detector and the CMS-TOTEM precision proton spectrometer
Measurements on vector boson scattering in the same-sign WW and fully leptonic ZZ channel, and a measurement of vector boson fusion of a Z boson are summarized. The three measurements are based on a dataset of proton--proton collisions at $\sqrt{s}=13\,\mathrm{Te\hspace{-.08em}V}$ with an integrated luminosity of $35.9\,\mathrm{fb}^{-1}$ recorded by the CMS experiment. The first observation for the electroweak production of a pair of same-sign W bosons is reported with an observed (expected) significance of 5.5 (5.7) standard deviations. The first measurement of vector boson fusion of a Z boso…
Several electroweak precision measurements are performed by the ATLAS and CMS collaborations at the LHC. The main ones are carried out using Drell-Yan production of single W and Z boson. They regard the measurement of the production cross sections of W and Z bosons, the mass of the W boson, and $\sin^2θ_W$. The results of the $\sin^2θ_W$ measurements have an accuracy of approximately twice that reached at LEP and SLD. Other measurements reported are about the Drell-Yan differential production cross section.
The CMS experiment has measured the electroweak production of top quark in different singly production modes: t-, tW- and s-channel. Recent results on inclusive and differential cross section measurements of t-channel at 13 TeV and of the fiducial cross section at 8 TeV are shown. The search for single top quark production in s-channel at 7 and 8 TeV as well as the search for associated production of Z boson and single top are presented. All measurements are in agreement with the Standard Model prediction and no sign of new physics is observed.
The measurement of the luminosity recorded by the CMS detector installed at LHC interaction point 5, using proton-proton collisions at $\sqrt{s} =$ 13 TeV in 2015 and 2016, is reported. The absolute luminosity scale is measured for individual bunch crossings using beam-separation scans (the van der Meer method), with a relative precision of 1.3% and 1.0% in 2015 and 2016, respectively. The dominant sources of uncertainty are related to residual differences between the measured beam positions and the ones provided by the operational settings of the LHC magnets, the factorizability of the proton…
Measurements of jet energy scale (JES) and resolution (JER) are presented, based on the legacy reconstruction of 13 TeV proton-proton collision data collected by the CMS experiment during the LHC Run 2 period from 2016-2018. Precision measurement of JES is of the utmost importance for the vast majority of physics measurements and searches at CMS. The high pileup, a harsh radiation environment, and time-dependent variations in detector response and calibration, all make precision JES measurement a challenging task. We present in-situ derivations of JES and JER based on CMS Run 2 data, as well a…
The electroweak production of single-top quarks in the $t$ channel can be changed by any deviation from the standard model, it is therefore an excellent opportunity to search for new physics. In this poster the recent cross-section measurement performed by the CMS collaboration is presented with the full 2015 dataset of the LHC Run II at a center-of-mass energy of 13 TeV. The cross section and the top/antitop ratio is extracted using a binned maximum likelihood fit to the distribution of a multivariate classifier in events containing one isolated muon in the final state.
Precision studies of top quark properties provide a unique playground to test the predictions of the standard model and to search for new physics. Reviewed results from the CMS experiment done with the data collected at 8 TeV include studies of top quark Wtb anomalous and FCNC couplings, polarization, CP-violation, and spin correlation effects. No significant deviations from the SM predictions are observed.
A measurement is presented of the cross section for electroweak production of a Z boson and a photon in association with two jets (Z$γ$jj) in proton-proton collisions. The Z boson candidates are selected through their decay into a pair of electrons or muons. The process of interest, electroweak Z$γ$jj production, is isolated by selecting events with a large dijet mass and a large pseudorapidity gap between the two jets. The measurement is based on data collected at the CMS experiment at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The observed significance …
A concise review of precision measurements in the Higgs sector of the Standard Model (SM) of particle physics is given using ATLAS and CMS data. The results are based on LHC Run-2 data, taken between 2015 and 2018. Impressive progress has been made since the discovery of the Higgs boson in 2012 for measuring all major production and decay modes. Good agreement with the SM predictions was observed in all measurements.
Uncertainty in Electroweak Symmetry Breaking in Models With High Scale Supersymmetry Breaking and its Impact on Interpretations of Searches For Supersymmetric Particles
As part of the Phase II upgrade program, the Compact Muon Solenoid (CMS) detector will incorporate a new timing layer designed to measure minimum ionizing particles (MIPs) with a time resolution of $\sim$30 ps. Precision timing will mitigate the impact of the challenging levels of pileup expected at the High Luminosity LHC. The time information assigned to each track will enable the use of 4D-vertexing which will render a 5-fold pile-up reduction, thus recovering the current conditions. Precision timing will also enable new time-based isolations and improved $b$-tagging algorithms. All of this…
We describe recent results from CMS and TOTEM on hard diffraction, diffractive jets and jet gap jet events. We also give the first sensitivities and limits on quartic anomalous couplings and axion-like particles at high mass using the LHC as a $γγ$ collider. The predicted sensitivities with 300 fb$^{-1}$ are better by two or three orders of magnitude compared to the more standard methods at the LHC without measuring intact protons after collision
