本文介绍了在欧洲核子研究中心（CERN）大型强子对撞机上首次寻找7 TeV pp碰撞产生的长寿命胶子的结果。这项研究寻找长寿命粒子的证据，这些粒子在CMS探测器中停止，并在光束交叉之间的静止期内衰减。在一个峰值瞬时光度为10^-32 /cm^2/s、积分亮度为10/pb、搜索间隔相当于LHC运行62小时的数据集中，没有观察到明显超出背景的现象。在95%的置信水平上，在13个数量级的胶子寿命胶子对生产的限制。当质量差（m_胶子-m_中性子）>100 GeV/c^2时，假设BR（胶子-> g中性子）= 100%，则在10^-6 s ~ 1000 s的寿命范围内，m_胶子< 370 GeV/c^2的情况被排除。
英文摘要：
The results of the first search for long-lived gluinos produced in 7 TeV pp collisions at the CERN Large Hadron Collider are presented. The search looks for evidence of long-lived particles that stop in the CMS detector and decay in the quiescent periods between beam crossings. In a dataset with a peak instantaneous luminosity of 10^-32 /cm^2/s, an integrated luminosity of 10/pb, and a search interval corresponding to 62 hours of LHC operation, no significant excess above background was observed. Limits at the 95% confidence level on gluino pair production over 13 orders of magnitude of gluino lifetime are set. For a mass difference (m_gluino-m_neutralino)>100 GeV/c^2, and assuming BR(gluino-> g neutralino)=100%, m_gluino < 370 GeV/c^2 are excluded for lifetimes from 10^-6 s to 1000 s.
These proceedings summarize the results of four analyses which searched for squarks and gluinos in hadronic final states with missing transverse momentum in 2.3 fb$^{-1}$ of data in proton-proton collisions at $\sqrt{s}=13$ TeV collected in the year 2015 with the CMS detector at the CERN LHC. Each analysis is characterized by a different kinematic variable that is sensitive to the presence of invisible particles, e.g., $M_\text{T2}$, $α_{\text{T}}$, and razor variables. We observed no significant deviation from the standard model prediction and placed limits on the production cross sections an…
A search has been performed for long-lived particles that could have come to rest within the CMS detector, using the time intervals between LHC beam crossings. The existence of such particles could be deduced from observation of their decays via energy deposits in the CMS calorimeter appearing at times that are well separated from any proton-proton collisions. Using a data set corresponding to an integrated luminosity of 18.6 inverse femtobarns of 8 TeV proton-proton collisions, and a search interval corresponding to 281 hours of trigger livetime, 10 events are observed, with a background pred…
A search for long-lived particles, which have come to rest within the ATLAS detector, is presented. The subsequent decays of these long-lived particles can produce high-momentum jets, resulting in large out-of-time energy deposits in the ATLAS calorimeters. These decays are detected using data collected during periods in the LHC bunch structure when collisions are absent. The analysed dataset is composed of events from proton-proton collisions produced by the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=13$ TeV and recorded by the ATLAS experiment during 2017 and 2018. The dat…
A search is presented for the decays of heavy exotic long-lived particles (LLPs) that are produced in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC and come to rest in the CMS detector. Their decays would be visible during periods of time well separated from proton-proton collisions. Two decay scenarios of stopped LLPs are explored: a hadronic decay detected in the calorimeter and a decay into muons detected in the muon system. The calorimeter (muon) search covers a period of sensitivity totaling 721 (744) hours in 38.6 (39.0) fb$^{-1}$ of data collected by the …
Searches for the pair-production of colored supersymmetric particles are presented. The results cover different scenarios of gluino and squark production, including models of split supersymmetry that predict long-lived gluinos, compressed supersymmetric mass spectra characterized by soft decay products as well as models with R-parity violation with low or no missing transverse momentum in the final state. The results are based on proton-proton collisions recorded at $\sqrt{s}=$ 13 TeV with the CMS detector.
The ATLAS and CMS experiments at the CERN LHC have collected about 25 inverse femtobarns (fb) of data each at the end of their 8 TeV run, and ruled out a huge swath of parameter space in the context of Minimally Supersymmetric Standard Model (MSSM). Limits on masses of the gluino have been pushed to above 1 TeV. These limits are however extremely model dependent and do not always reflect the level of exclusion. So far the limits on the gluino mass using the simplified model approach only constrained its value using its three-body decays. We show in this work that already existing ATLAS and CMS…
Search for squarks and gluinos using final states with jets and missing transverse momentum with the ATLAS detector in sqrt(s) = 7 TeV proton-proton collisions
Search for gluinos in events with two same-sign leptons, jets and missing transverse momentum with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV
Search for squarks and gluinos using final states with jets and missing transverse momentum with the ATLAS detector in sqrt(s) = 7 TeV proton-proton collisions
Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using 4.7 fb^-1 of sqrt(s) = 7 TeV proton-proton collision data
The classic searches for supersymmetry have not given any strong indication for new physics. Therefore CMS is designing dedicated searches to target the more difficult and specific supersymmetry scenarios. This contribution present three such recent searches based on 13 TeV proton-proton collisions recorded with the CMS detector in 2016, 2017 and 2018: a search for heavy gluinos cascading via heavy next-to-lightest neutralino in final states with boosted Z bosons and missing transverse momentum; a search for compressed supersymmetry in final states with soft taus; and a search for compressed, …
We present results from a generic search for strongly produced supersymmetric particles in pp collisions in the multijet + missing transverse momentum final state. The data sample corresponds to 2.3 fb$^{-1}$ recorded by the CMS experiment at $\sqrt{s}=13$ TeV. This search is motivated by supersymmetry (SUSY) models that avoid fine-tuning of the higgs mass. In such models, certain strongly produced SUSY particles, including the gluino and top squark, are predicted to have masses on the order of a TeV. These particles also have some of the highest production cross sections in SUSY and give rise…
A search for long-lived particles decaying to displaced, nonprompt jets and missing transverse momentum is presented. The data sample corresponds to an integrated luminosity of 137 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC in 2016-2018. Candidate signal events containing nonprompt jets are identified using the timing capabilities of the CMS electromagnetic calorimeter. The results of the search are consistent with the background prediction and are interpreted using a gauge-mediated supersymmetry breaking reference…
We discuss a search for natural Supersymmetry in events with at least one bottom-quark jet using razor variables in proton-proton collisions at 8 TeV with the CMS detector. The event distribution in the plane defined by the razor variables $R^2$ and $M_R$ is studied, searching for a peaking signal on top of a smoothly falling standard model background. The data are consistent with the expected background, modeled by a template function. The 95% C.L. exclusion limit on the masses of the gluino and lightest supersymmetric particle in a benchmark simplified model is presented. For a lightest supe…
A search for squarks and gluinos in final states containing high-$p_{\rm T}$ jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in $\sqrt{s}=8$ TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of $20.3 \mathrm{fb}^{-1}$. No significant excess above the Standard Model expectation is observed. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest super…
A search for the production of long-lived particles in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC is presented. The search is based on data collected by the CMS experiment in 2016-2018, corresponding to a total integrated luminosity of 137 fb$^{-1}$. This search is designed to be sensitive to long-lived particles with mean proper decay lengths between 0.1 and 1000 mm, whose decay products produce a final state with at least one displaced vertex and missing transverse momentum. A machine learning algorithm, which improves the background rejection power by more…
Five mutually exclusive searches for supersymmetry are presented based on events in which b jets and four W bosons are produced in proton-proton collisions at sqrt(s) = 8 TeV. The data, corresponding to an integrated luminosity of 19.5 inverse femtobarns, were collected with the CMS experiment at the CERN LHC in 2012. The five studies differ in the leptonic signature from the W boson decays, and correspond to all-hadronic, single-lepton, opposite-sign dilepton, same-sign dilepton, and greater-than-or-equal-to-3 lepton final states. The results of the five studies are combined to yield 95% conf…
A search for supersymmetry is performed in events with a single electron or muon in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 2.3 inverse femtobarns. Several exclusive search regions are defined based on the number of jets and b-tagged jets, the scalar sum of the jet transverse momenta, and the scalar sum of the missing transverse momentum and the transverse momentum of the lepton. The observed event yields in data are consistent with the expected backgrounds from standard…
The results from the CMS search for supersymmetric particles based on Run-2 data recorded at a center-of-mass energy of 13 TeV are summarized. Strong and weak production of SUSY scenarios are considered. Results presented include the searches for squarks and gluinos, direct production of charginos, neutralinos, and sleptons. These searches involve final state objects comprising jets, missing transverse momentum, electrons or muons, taus or photons, as well as long-lived particles. The data in these searches are found to be consistent with standard model predictions and no significant excess is…
Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb^-1 of sqrt(s) = 7 TeV proton-proton collisions
A search for supersymmetry (SUSY) is performed in final states comprising one or more jets and missing transverse momentum using data from proton-proton collisions at a centre-of-mass energy of 13 TeV. The data were recorded with the CMS detector at the CERN LHC in 2016 and correspond to an integrated luminosity of 35.9 fb$^{-1}$. The number of signal events is found to agree with the expected background yields from standard model processes. The results are interpreted in the context of simplified models of SUSY that assume the production of gluino or squark pairs and their prompt decay to qua…
A search for production of the supersymmetric partners of the top quark, top squarks, is presented. The search is based on proton-proton collision events containing multiple jets, no leptons, and large transverse momentum imbalance. The data were collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 137 fb$^{-1}$. The targeted signal production scenarios are direct and gluino-mediated top squark production, including scenarios in which the top squark and neutralino masses are nearly degenerate. The search utilizes no…
The razor approach to search for R-parity conserving supersymmetric particles is described in detail. Two analyses are considered: an inclusive search for new heavy particle pairs decaying to final states with at least two jets and missing transverse energy, and a dedicated search for final states with at least one jet originating from a bottom quark. For both the inclusive study and the study requiring a bottom-quark jet, the data are examined in exclusive final states corresponding to all-hadronic, single-lepton, and dilepton events. The study is based on the data set of proton-proton collis…
A search for physics beyond the standard model in final states with at least one photon, large transverse momentum imbalance, and large total transverse event activity is presented. Such topologies can be produced in gauge-mediated supersymmetry models in which pair-produced gluinos or squarks decay to photons and gravitinos via short-lived neutralinos. The data sample corresponds to an integrated luminosity of 35.9 inverse femtobarns of proton-proton collisions at sqrt(s) = 13 TeV recorded by the CMS experiment at the LHC in 2016. No significant excess of events above the expected standard mo…
An inclusive search for supersymmetry using razor variables is performed in events with four or more jets and no more than one lepton. The results are based on a sample of proton-proton collisions corresponding to an integrated luminosity of 2.3 inverse femtobarns collected with the CMS experiment at a center-of-mass energy of sqrt(s) = 13 TeV. No significant excess over the background prediction is observed in data, and 95% confidence level exclusion limits are placed on the masses of new heavy particles in a variety of simplified models. Assuming that pair-produced gluinos decay only via thr…
Results are reported from a search for supersymmetric particles in proton-proton collisions in the final state with a single, high transverse momentum lepton; multiple jets, including at least one b-tagged jet; and large missing transverse momentum. The data sample corresponds to an integrated luminosity of 2.3 inverse femtobarns at sqrt(s) = 13 TeV, recorded by the CMS experiment at the LHC. The search focuses on processes leading to high jet multiplicities, such as gluino pair production with gluinos to t t-bar neutralino[1]. The quantity M[J], defined as the sum of the masses of the large-r…
A search has been performed for pair-produced resonances decaying into three jets. The proton-proton collision data used for this analysis were collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 35.9 fb$^{-1}$. The mass range from 200 to 2000 GeV is explored in four separate mass regions. The observations show agreement with standard model expectations. The results are interpreted within the framework of $R$-parity violating SUSY, where pair-produced gluinos decay to a six quark final state. Gluino masses below 1500 GeV ar…
A search for new physics is performed based on all-hadronic events with large missing transverse momentum produced in proton-proton collisions at sqrt(s) = 13 TeV. The data sample, corresponding to an integrated luminosity of 2.3 inverse femtobarns, was collected with the CMS detector at the CERN LHC in 2015. The data are examined in search regions of jet multiplicity, tagged bottom quark jet multiplicity, missing transverse momentum, and the scalar sum of jet transverse momenta. The observed numbers of events in all search regions are found to be consistent with the expectations from standard…
A search is presented for supersymmetry in all-hadronic events with missing transverse momentum and tagged top quarks. The data sample was collected by the CMS detector at the LHC and corresponds to an integrated luminosity of 2.3 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 13 TeV. Search regions are defined using the properties of reconstructed jets, the multiplicity of bottom and top quark candidates, and an imbalance in transverse momentum. With no statistically significant excess of events observed beyond the expected contributions from the standard model, …
Results are reported for a search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ collected at a center-of-mass energy of 13 TeV using the CMS detector. The results are interpreted in the context of models of gauge-mediated supersymmetry breaking. Production cross section limits are set on gluino and squark pair production in this framework. Gluino masses below 1.86 TeV and squark masses below 1.59 TeV are excluded at 95% confidence level.
Searches for new physics by the CMS collaboration are interpreted in the framework of the phenomenological minimal supersymmetric standard model (pMSSM). The data samples used in this study were collected at sqrt(s) = 7 and 8 TeV and have integrated luminosities of 5.0 and 19.5 inverse-femtobarns, respectively. A global Bayesian analysis is performed, incorporating results from a broad range of CMS supersymmetry searches, as well as constraints from other experiments. Because the pMSSM incorporates several well-motivated assumptions that reduce the 120 parameters of the MSSM to just 19 paramet…
Results are reported from a search for R-parity violating supersymmetry in proton-proton collision events collected by the CMS experiment at a center-of-mass energy of sqrt(s) = 8 TeV. The data sample corresponds to an integrated luminosity of 17.6 inverse femtobarns. This search assumes a minimal flavor violating model in which the lightest supersymmetric particle is a long-lived neutralino or gluino, leading to a signal with jets emanating from displaced vertices. In a sample of events with two displaced vertices, no excess yield above the expectation from standard model processes is observe…
An inclusive search is presented for long-lived particles using displaced jets. The search uses a data sample collected with the CMS detector at the CERN LHC in 2017 and 2018, from proton-proton collisions at a center-of-mass energy of 13 TeV. The results of this search are combined with those of a previous search using a data sample collected with the CMS detector in 2016, yielding a total integrated luminosity of 132 fb$^{-1}$. The analysis searches for the distinctive topology of displaced tracks and displaced vertices associated with a dijet system. For a simplified model, where pair-produ…
