Search for supersymmetry in events with soft leptons, low jet multiplicity, and missing transverse energy in proton–proton collisions at √ s = TeV

Results are presented from a search for supersymmetric particles in scenarios with small mass splittings. The data sample corresponds to 19 . 7 fb − 1 of proton–proton collisions recorded by the CMS experiment at √ s = 8 TeV. The search targets top squark ( (cid:2) t) pair production in scenarios with mass differences (cid:3) m = m ( (cid:2) t ) − m ( (cid:2) χ 01 ) below the W-boson mass and with top-squark decays in the four-body mode ( (cid:2) t → b (cid:5) ν (cid:2) χ 01 ), where the neutralino ( (cid:2) χ 01 ) is assumed to be the lightest supersymmetric particle (LSP). The signature includes a high transverse momentum ( p T ) jet associated with initial-state radiation, one or two low- p T leptons, and significant missing transverse energy. The event yields observed in data are consistent with the expected background contributions from standard model processes. Limits are set on the cross section for top squark pair production as a function of the (cid:2) t and LSP masses. Assuming a 100% branching fraction for the four-body decay mode, top-squark masses below 316 GeV are excluded for (cid:3) m = 25 GeV at 95% CL. The dilepton data are also interpreted under the assumption of chargino– neutralino production, with subsequent decays to sleptons or sneutrinos. Assuming a difference between the common (cid:2) χ + 1 / (cid:2) χ 02 mass and the LSP mass of 20 GeV and a τ -enriched decay scenario, masses in the range m ( (cid:2) χ + 1 ) < 307 GeV are excluded at 95% CL. © 2016 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP 3 .

[1]  Lisa Randall,et al.  What Is Dark Matter? , 2018, Nature.

[2]  M. P. Casado,et al.  Search for the direct production of charginos and neutralinos in final states with tau leptons in $$\sqrt{s} = 13\,\mathrm{TeV}$$s=13TeVpp collisions with the ATLAS detector , 2018, The European physical journal. C, Particles and fields.

[3]  N. Dhingra.  Search for Supersymmetry in the Vector Boson Fusion topology in proton-proton collisions at $\sqrt{s}=8$ TeV , 2017 .

[4]  J. T. Childers,et al.  ATLAS Run 1 searches for direct pair production of third-generation squarks at the Large Hadron Collider , 2015, The European Physical Journal. C, Particles and Fields.

[5]  S. M. Etesami,et al.  Searches for third-generation squark production in fully hadronic final states in proton-proton collisions at s=8$$ \sqrt{s}=8 $$ TeV , 2015 .

[6]  C. Collaboration,et al.  Searches for third-generation squark production in fully hadronic final states in proton-proton collisions at sqrt(s) = 8 TeV , 2015, 1503.08037.

[7]  C. Collaboration,et al.  Performance of electron reconstruction and selection with the CMS detector in proton-proton collisions at √s = 8 TeV , 2015, 1502.02701.

[8]  Atlas Collaboration.  Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in pp Collisions at √s = 8 TeV Using the ATLAS Detector , 2014, 1412.4742.

[9]  Khachatryan,et al.  Performance of the CMS missing transverse momentum reconstruction in pp data at √s = 8 TeV , 2014, 1411.0511.

[10]  J. T. Childers,et al.  Search for top squark pair production in final states with one isolated lepton, jets, and missing transverse momentum in s\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} , 2014, Journal of High Energy Physics.

[11]  M. Mühlleitner,et al.  Light stop decays: implications for LHC searches , 2014, The European Physical Journal C.

[12]  Scoap.  Measurement of WZ and ZZ production in pp collisions at s=8TeV in final states with b-tagged jets , 2014 .

[13]  S. M. Etesami,et al.  Searches for electroweak production of charginos, neutralinos, and sleptons decaying to leptons and W, Z, and Higgs bosons in pp collisions at 8 TeV , 2014, The European physical journal. C, Particles and fields.

[14]  V. M. Ghete,et al.  Measurement of the properties of a Higgs boson in the four-lepton final state , 2014 .

[15]  P. Catastini,et al.  Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} , 2014, Journal of High Energy Physics.

[16]  C. Collaboration,et al.  Measurement of inclusive W and Z boson production cross sections in pp collisions at sqrt(s) = 8 TeV , 2014, 1402.0923.

[17]  Zhenyu Han,et al.  Hunting quasidegenerate Higgsinos , 2014, 1401.1235.

[18]  J. Zurita,et al.  Compressed electroweakino spectra at the LHC , 2013, 1312.7350.

[19]  Andrea Benaglia,et al.  Measurement of the prompt J/ψ and ψ(2S) polarizations in pp collisions at s=7 TeV , 2013 .

[20]  B. Fuks,et al.  Revisiting slepton pair production at the Large Hadron Collider , 2013, 1310.2621.

[21]  B. Fuks,et al.  Precision predictions for electroweak superpartner production at hadron colliders with Resummino , 2013, The European Physical Journal C.

[22]  M. Pierini,et al.  The light stop window , 2012, 1212.6847.

[23]  C. Collaboration,et al.  Identification of b-quark jets with the CMS experiment , 2012, 1211.4462.

[24]  P. D. Luckey,et al.  Performance of CMS muon reconstruction in pp collision events at √s = 7 TeV , 2012 .

[25]  B. Fuks,et al.  Gaugino production in proton-proton collisions at a center-of-mass energy of 8 TeV , 2012, 1207.2159.

[26]  S. Forte,et al.  Parton distributions with LHC data , 2012, 1207.1303.

[27]  V. M. Ghete,et al.  Measurement of the polarization of W bosons with large transverse momenta in W + jets events at the LHC. , 2011, Physical review letters.

[28]  F. Maltoni,et al.  MadGraph 5: going beyond , 2011, 1106.0522.

[29]  M. Kramer,et al.  SQUARK AND GLUINO HADROPRODUCTION , 2011, 1105.1110.

[30]  T. Gleisberg,et al.  Left-handed W bosons at the LHC , 2011, 1103.5445.

[31]  J. Huston,et al.  New parton distributions for collider physics , 2010, 1007.2241.

[32]  T. Han,et al.  Nearly Degenerate Gauginos and Dark Matter at the LHC , 2010, 1004.4902.

[33]  M. Kramer,et al.  Soft-gluon resummation for squark and gluino hadroproduction , 2009, 0909.4418.

[34]  A. Kulesza,et al.  Soft gluon resummation for the production of gluino-gluino and squark-antisquark pairs at the LHC , 2009, 0905.4749.

[35]  Alexander Schmidt,et al.  Fast simulation of the CMS detector at the LHC , 2008, 2008 IEEE Nuclear Science Symposium Conference Record.

[36]  João Paulo Teixeira,et al.  The CMS experiment at the CERN LHC , 2008 .

[37]  A. Kulesza,et al.  Threshold resummation for squark-antisquark and gluino-pair production at the LHC. , 2008, Physical review letters.

[38]  M. Cacciari,et al.  The anti-$k_t$ jet clustering algorithm , 2008, 0802.1189.

[39]  P. Nason,et al.  Matching NLO QCD computations with Parton Shower simulations: the POWHEG method , 2007, 0709.2092.

[40]  R. S. Thorne,et al.  Parton distributions for the LHC , 2007, 0901.0002.

[41]  T. Junk,et al.  Confidence Level Computation for Combining Searches with Small Statistics , 1999, hep-ex/9902006.

[42]  P. Zerwas,et al.  Squark and gluino production at hadron colliders , 1996, hep-ph/9610490.

[43]  J. Casas,et al.  One-loop analysis of the electroweak breaking in supersymmetric models and the fine-tuning problem , 1993, hep-ph/9303291.

[44]  U. Amaldi,et al.  Supersymmetry , 1991, Science.

[45]  R. Barbieri,et al.  Upper Bounds on Supersymmetric Particle Masses , 1988 .

[46]  Dawson,et al.  Search for supersymmetric particles in hadron-hadron collisions. , 1985, Physical review. D, Particles and fields.

[47]  S. Ferrara,et al.  Gauge models with spontaneously broken local supersymmetry , 1982 .

[48]  Romesh K. Kaul,et al.  Cancellation of quadratically divergent mass corrections in globally supersymmetric spontaneously broken gauge theories , 1982 .

[49]  Savas Dimopoulos,et al.  Softly Broken Supersymmetry and SU(5) , 1981 .

[50]  P. Fayet,et al.  Phenomenology of the production, decay, and detection of new hadronic states associated with supersymmetry , 1978 .

[51]  B. Zumino,et al.  Supergauge Transformations in Four-Dimensions , 1974 .

[52]  Andrea Benaglia,et al.  Search for top-squark pair production in the single-lepton final state in pp collisions at s√=8 TeV , 2018 .

[53]  Bruce Yabsley,et al.  Search for the electroweak production of supersymmetric particles in √ s = 8 TeV pp collisions with the ATLAS detector , 2016 .

[54]  E. E. Kangal,et al.  Measurement of the W + W − cross section in pp collisions at √ s = 8 TeV and limits on anomalous gauge couplings The CMS Collaboration , 2022 .

[55]  Bruce Yabsley,et al.  Search for pair-produced third-generation squarks decaying via charm quarks or in compressed supersymmetric scenarios in pp collisions at √s = 8 TeV with the ATLAS detector , 2014 .

[56]  J. T. Childers,et al.  Measurement of the W+W- production in pp collisions at √s = 7 TeV with the ATLAS detector and limits on anomalous WWZ and WWγ couplings , 2013 .

[57]  CMS Collaboration.  Performance of τ-lepton reconstruction and identification in CMS , 2012 .

[58]  Procedure for the LHC Higgs boson search combination in Summer 2011 , 2011 .

[59]  M. Carena,et al.  4 ANL-HEP-PR-0427 EFI-04-08 FERMILAB-PUB-04 / 034-T Dark Matter , Light Stops and Electroweak Baryogenesis , 2008 .

[60]  A. Nelson.  Dynamical Breaking of Supersymmetry , 2008 .

[61]  Howard E. Haber,et al.  The Search for Supersymmetry: Probing Physics Beyond the Standard Model , 1985 .

[62]  Particle – Flow Event Reconstruction in CMS and Performance for Jets , Taus , 2022 .