Physics Letters B 761 (2016) 31–52 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb ϒ(nS) polarizations versus particle multiplicity in pp collisions at √ s = 7 TeV .The CMS Collaboration � CERN, Switzerland a r t i c l e i n f o a b s t r a c t Article history: Received 9 March 2016 Received in revised form 5 July 2016 Accepted 26 July 2016 Available online 2 August 2016 Editor: M. Doser Keywords: CMS Physics Quarkonium production Quarkonium polarization QCD medium effects The polarizations of the ϒ(1S), ϒ(2S), and ϒ(3S) mesons are measured as a function of the charged particle multiplicity in proton–proton collisions at √ s = 7 TeV. The measurements are performed with a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb−1. The results are extracted from the dimuon decay angular distributions, in two ranges of ϒ(nS) transverse momentum (10–15 and 15–35 GeV), and in the rapidity interval |y| < 1.2. The results do not show significant changes from low- to high-multiplicity pp collisions, although large uncertainties preclude definite statements in the ϒ(2S) and ϒ(3S) cases. © 2016 The Author(s). 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 SCOAP3. 1. Introduction Studies of heavy-quarkonium production contribute to an im- proved understanding of hadron formation within the context of quantum chromodynamics (QCD) [1]. Quarkonium production is expected to proceed in two steps [2]. First, a heavy quark– antiquark pair, QQ, is produced, with angular momentum L and spin S . Then this “pre-resonance” binds into the measured quarko- nium state through a nonperturbative evolution that may change L and/or S . The short-distance QQ production cross sections are functions of the QQ momentum and are calculated in perturba- tive QCD [3–6], while the probabilities that QQ pairs of differ- ent quantum properties form the observed quarkonium state are parametrized by momentum-independent long-distance matrix el- ements (LDMEs). Since they are expected to scale with powers of the heavy-quark velocity squared, v2, in the nonrelativistic limit (v2 � 1) most LDMEs are negligible and S-wave vector quarkonia should be dominantly formed from QQ pairs produced as colour- singlet, 3 S[1] 1 , or as one of the 1 S[8] 0 , 3 S[8] 1 and 3 P [8] J colour-octet states. While the colour-singlet LDME can be calculated with po- tential models, the others, reflecting the complexity of the evo- lution of a coloured QCD system into a formed hadron, are de- termined through phenomenological analyses of quarkonium pro- duction data [3–7]. Polarization data play a central role in these � E-mail address: cms-publication-committee-chair@cern.ch. analyses [7], which are performed in the zero-momentum frame of the quarkonium state (and, approximately, of the QQ pair) and can directly reveal the quantum properties of the QQ, relying in most cases only on basic angular-momentum analysis. For exam- ple, 1 S[8] 0 QQ states evolve into unpolarized 3 S1 quarkonia, while 3 S[8] 1 states, with quantum numbers identical to those of a gluon, lead to transversely polarized 3 S1 quarkonia. The factorization hypothesis of nonrelativistic QCD implicitly assumes that the LDMEs are universal constants, independent of the short-distance process that created the QQ: the same LDMEs should be extracted from proton–(anti)proton and e+e− data, for example. However, cross section and polarization measurements at high transverse momentum, pT, are currently limited to pp colli- sions, so that the LDME universality hypothesis remains a nontriv- ial assumption requiring direct experimental investigation. Since the nonperturbative quarkonium formation process involves inter- actions with the QCD medium surrounding the QQ state, allowing it to neutralize its net colour through emission or absorption of soft gluons, it is important to verify if the polarizations (directly related to the LDMEs) depend on the complexity of the hadronic environment created by the collision. Probing if the polarizations are affected by an increase in the multiplicity of particles pro- duced in pp collisions, the topic of the present analysis, is a first step in such a study, to be followed by analogous investigations us- ing proton–nucleus and nucleus–nucleus data collected at different collision centralities. Such studies are crucial for a reliable interpre- tation of the quarkonium suppression patterns seen in high-energy http://dx.doi.org/10.1016/j.physletb.2016.07.065 0370-2693/© 2016 The Author(s). 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 SCOAP3. http://dx.doi.org/10.1016/j.physletb.2016.07.065 http://www.ScienceDirect.com/ http://www.elsevier.com/locate/physletb http://creativecommons.org/licenses/by/4.0/ mailto:cms-publication-committee-chair@cern.ch http://dx.doi.org/10.1016/j.physletb.2016.07.065 http://creativecommons.org/licenses/by/4.0/ http://crossmark.crossref.org/dialog/?doi=10.1016/j.physletb.2016.07.065&domain=pdf 32 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 nuclear collisions (see Ref. [8] and references therein) and of their relation to signatures of quark–gluon plasma formation [9–11]. While changes in integrated yields or in pT and rapidity, y, distri- butions can be caused by effects such as modified parton densities in the nucleus or parton energy loss, the observation of changes in quarkonium polarization would be a direct signal of a modification in the bound-state formation mechanism. This Letter reports how the polarizations of the ϒ(1S), ϒ(2S), and ϒ(3S) mesons produced in pp collisions at a centre-of-mass energy of 7 TeV change as a function of charged particle mul- tiplicity, Nch. It complements two observations made for pp and pPb collisions [12]: the ϒ(nS) cross sections, normalised by their Nch-integrated values, increase with Nch; the ϒ(2S) and ϒ(3S) cross sections, normalised by the ϒ(1S) value, decrease with Nch. The measurements are performed using a dimuon data sam- ple collected in 2011 by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 4.9 fb−1, and follow the analysis method used in the Nch-integrated measurement [13]. The dimuon mass distribution is used to separate the ϒ(nS) sig- nals from each other and from muon pairs due to other processes, such as decays of heavy flavour mesons. The ϒ(nS) polarizations are characterized through three parameters, �λ = (λϑ , λϕ, λϑϕ), re- flecting the anisotropy of the angular distribution of the decay muons [14], W (cosϑ,ϕ|�λ) ∝ 1 (3 + λϑ) (1 + λϑ cos2 ϑ + + λϕ sin2 ϑ cos 2ϕ + λϑϕ sin 2ϑ cosϕ), (1) where ϑ and ϕ are the polar and azimuthal angles, respectively, of the μ+ . These �λ parameters, as well as the frame-invariant pa- rameter λ̃ = (λϑ + 3 λϕ)/(1 −λϕ) [15], are measured in the centre- of-mass helicity frame (HX), where the z axis coincides with the direction of the ϒ momentum. The y axis of the polarization frame is reversed between positive and negative rapidity, a defi- nition that avoids the cancellation of λϑϕ when integrating events over a symmetrical range in rapidity. This is explained in Ref. [16], which provides a pedagogical introduction to quarkonium polar- ization physics. As in the previous CMS quarkonium polarization measurements [13,17], the analysis is exclusively based on mea- sured data: the 3-momentum vectors of the two muons (contain- ing the spin alignment information of the decaying ϒ(nS) mesons) and the muon detection efficiencies. 2. CMS detector and data analysis The CMS apparatus is based on a superconducting solenoid of 6 m internal diameter, providing a 3.8 T field. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crys- tal electromagnetic calorimeter, and a brass and scintillator hadron calorimeter. Muons are measured with drift tubes, cathode strip chambers, and resistive-plate chambers. The main detectors used in this analysis are the silicon tracker and the muon system, which enable the measurement of muon momenta over the pseudora- pidity range |η| < 2.4. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the relevant kinematic variables, can be found in Ref. [18]. The events were collected using a two-level trigger system. The first level uses custom hardware processors to select events with two muons. The high-level trigger, adding information from the silicon tracker, selects opposite-sign muon pairs of invariant mass 8.5 < M < 11.5 GeV, |y| < 1.25 and pT > 5 or 7 GeV (depending on the instantaneous luminosity); the dimuon vertex fit χ2 prob- ability must exceed 0.5% and the two muons must have a distance of closest approach smaller than 5 mm. Although the trigger logic Fig. 1. Charged particle multiplicity distribution of the events selected for the anal- ysis. does not reject events on the basis of the pT of the single muons, at mid-rapidity the bending induced by the magnetic field pre- vents muons of pT smaller than ∼3 GeV from reaching the muon stations. The offline analysis selects muon tracks with hits in more than ten tracker layers, at least two of which are in the pixel layers, and matched with segments in the muon system. They must have a good track fit quality, point to the interaction region, and match the muon objects that triggered the event. The selected muons are required to satisfy |η| < 1.6 and to have pT above 4.5, 3.5, and 3 GeV for |η| < 1.2, 1.2 < |η| < 1.4, and 1.4 < |η| < 1.6, re- spectively, to ensure reliable detection and trigger efficiencies. The combinatorial background from uncorrelated muons is suppressed by requiring a dimuon vertex fit χ2 probability larger than 1% and by rejecting events where the distance between the dimuon ver- tex and the primary vertex is larger than twice its resolution. In events with multiple reconstructed primary vertices (pileup), the one nearest to the point of closest approach between the trajectory of the dimuon and the beam line is selected. The Nch variable is computed by counting “high purity” [19] charged tracks, excluding the two muons, of |η| < 2.4, pT > 500 MeV, and pT measured with better than 10% relative accuracy. Acceptance and reconstruction efficiencies are not corrected for. Each track is assigned a weight reflecting the likelihood that it belongs to the primary vertex [19]; tracks consistent with the vertex have a weight close to unity. The migration of events from one Nch bin to the next, caused by in- advertently counting spurious tracks produced in near-by pileup vertices, is kept negligible by rejecting events with more than 16 vertices. Fig. 1 shows the Nch distribution of the events selected in this analysis. The dimuon mass distribution, shown in Fig. 2, is well de- scribed by three Crystal-Ball functions [20], one per ϒ(nS) peak, and a second-order polynomial function representing the under- lying continuum, determined from the mass sidebands, 8.6–8.9 and 10.6–11.4 GeV. The dimuon mass resolution is σ ≈ 80 MeV, slightly dependent on pT. The ϒ(nS) signal mass regions are defined as the ±1 σ windows around the fitted means of the Crystal-Ball functions. The corresponding cross-feed between the three peaks is negligible. The analysis is performed in five Nch bins, 0–10, 10–20, 20–30, 30–40, and 40–60, sufficiently numer- ous and narrow to probe potential variations of the polarizations, and in two ϒ(nS) pT ranges, 10–15 and 15–35 GeV. The dimuons are integrated within |y| < 1.2. The lower pT ϒ(3S) polarization The CMS Collaboration / Physics Letters B 761 (2016) 31–52 33 Fig. 2. Dimuon mass distributions in the ϒ(nS) region for two pT ranges. measurement merges the two highest Nch bins, to reduce the background-related systematic uncertainties. In the lowest Nch bin, the background fractions in the signal mass regions, fBg, are ap- proximately 3%, 7%, and 10% for the ϒ(1S), ϒ(2S), and ϒ(3S), respectively. The corresponding values in the highest Nch bin are ∼4 and ∼2.5 times higher in the 10–15 and 15–35 GeV pT ranges, respectively. All analysis bins have signal yields sufficiently high for a reliable measurement, the worst case being the 2300 ϒ(3S) events in the highest Nch bin at high pT. All signal yields and back- ground fractions are tabulated in the supplemental material. The single-muon detection efficiencies are measured with a “tag-and-probe” technique [21], using event samples collected with triggers specifically designed for this purpose, including a sample enriched in dimuons from J/ψ decays where a muon is combined with another track and the pair is required to have an invariant mass within 2.8–3.4 GeV. The procedure was validated with de- tailed Monte Carlo simulation studies. The measured efficiencies are parametrized as a function of muon pT, in eight |η| bins. Their uncertainties, ∼2–3%, reflecting the statistical precision of the cal- ibration samples and possible imperfections of the parametriza- tion, are independent of Nch and identical for the three ϒ(nS) states. These global uncertainties do not affect the search for poten- tial variations of the polarizations from low- to high-multiplicity events. The trigger and the selection criteria could potentially in- troduce differences between the dimuon detection efficiencies and the product of the efficiencies of the two single muons. Simulation studies reveal that such correlations have a negligible dependence on cosϑ and ϕ , in the phase space of this analysis [13]. The resid- ual angular dependences are accounted for in the evaluation of the global systematic uncertainties. 3. Extraction of the polarization parameters The two-dimensional angular distribution, in cos ϑ and ϕ , of the background corresponding to a given ϒ(nS) state is eval- uated as a weighted average of the distributions measured in the two mass sidebands, the weights reflecting (linearly) the dif- ferences between the ϒ(nS) mass and the median masses of the sidebands. The background component is subtracted on an event-by-event basis using a likelihood-ratio criterion, randomly selecting and removing a fraction fBg of events distributed ac- cording to the (pT, |y|, M, cosϑ, ϕ) distribution of the background model [13]. The posterior probability density (PPD) for the average values of the ϒ(nS) polarization parameters (�λ) inside a particular Fig. 3. Distributions of cos ϑ (top) and ϕ (bottom), for the ϒ(2S) in a representative analysis bin. The curves represent two polarization scenarios (dashed and dotted lines, defined in the legends) and the measured case (solid lines: λϑ = 0.237, λϕ = −0.027, λϑϕ = −0.025). bin is then defined as a product over the remaining (signal-like) events i, P(�λ) = ∏ i E(�p (i) 1 , �p (i) 2 ), (2) where E represents the event probability distribution as a function of the muon momenta �p1,2 in event i. This analysis method does not use model-dependent (cos ϑ, ϕ) acceptance maps; each event is attributed a probability reflecting the full event kinematics (not only cosϑ and ϕ) and the values of the polarization parameters, E(�p1, �p2) = 1 N (�λ) W (cosϑ,ϕ|�λ)ε(�p1, �p2), (3) where ε(�p1, �p2) is the measured detection efficiency. The normal- ization factor N (�λ) is calculated by integrating W · ε over cosϑ and ϕ uniformly, using (pT, |y|, M) distributions determined from the background-subtracted data. To account for the statistical fluc- tuations related to its random nature, the background subtraction procedure is repeated 50 times. Fig. 3 compares the cosϑ and ϕ distributions measured for ϒ(2S) signal events of 15 < pT < 35 GeV and 10 < Nch < 20 with 34 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 curves representing the “best fit”. For illustration, curves reflect- ing extreme polarization scenarios are also shown: fully transverse (λϑ = +1) and fully longitudinal (λϑ = −1) in the cosϑ panel, and λϕ = ±0.5 in the ϕ panel (|λϕ | must be smaller than 0.5 if λϑ = 0 [14]). Each of the systematic uncertainties on the polarization param- eters caused by the analysis framework and the detection efficien- cies is individually evaluated through 50 statistically independent pseudo-experiments. For each effect, the systematic uncertainty is the difference between the injected and resulting parameters. The robustness of the framework to measure the signal polarization is validated for several signal and background polarization scenarios. The impact of residual biases that could be caused by uncertainties on the muon or dimuon efficiencies is evaluated by extracting the polarization parameters after applying corresponding variations to the input efficiencies. The background model uncertainty is evalu- ated by modifying the relative weights of the low- and high-mass sidebands when building the background distributions. A broad range of hypotheses is considered, including the assumption that the background under the ϒ(1S) (ϒ(3S)) peak resembles exclu- sively the low-mass (high-mass) sideband, or assuming that it is reproduced by an equal mixture of the two sideband distributions. Several systematic uncertainties have similar levels, except in the highest Nch bins and the lowest pT range, where the background model uncertainty dominates, especially for the ϒ(2S) and ϒ(3S) states. For the ϒ(1S) state and in the HX frame, the Nch-dependent systematic uncertainties are ∼0.1 for λϑ and ∼0.03–0.05 for λϕ and λϑϕ , slightly increasing with Nch. The corresponding ϒ(2S) and ϒ(3S) values are slightly larger: ∼0.2 for λϑ , ∼0.04 for λϕ , and ∼0.05–0.08 for λϑϕ . The statistical uncertainties are negligi- ble for the ϒ(1S) state and become dominant for the ϒ(2S) and ϒ(3S) states, as Nch increases. 4. Results The final PPD of the polarization parameters is an envelope of the PPDs corresponding to all hypotheses considered in the evaluation of the systematic uncertainties. In each analysis bin, the central values and 68.3% confidence level (CL) uncertainties of each polarization parameter are evaluated from the corresponding one-dimensional marginal posterior, calculated by numerical inte- gration. In the HX frame, the λ parameters are measured with negligible correlations, as illustrated by Fig. 4, which shows the two-dimensional marginals of the PPD in the λϕ vs. λϑ and λϑϕ vs. λϕ planes, for a representative analysis bin. Fig. 5 shows the λϑ , λϕ , λϑϕ , and λ̃ values measured in the HX frame for the three ϒ(nS) states, in both pT ranges. The corre- sponding numerical results are tabulated in the supplemental ma- terial. The λ̃ values have also been measured in the Collins–Soper frame (CS) [22], whose z axis is the average of the two beam direc- tions in the ϒ rest frame, and in the perpendicular helicity frame (PX) [23], orthogonal to the CS frame. The three measurements agree with each other, within systematic uncertainties (similar in all frames), as required in the absence of unaccounted systematic effects [24]. Regarding the ϒ(1S) results, all the λ parameters are close to zero, indicating essentially unpolarized production, as expected if the mesons included in this analysis would be dominantly pro- duced through the unpolarized 1 S[8] 0 pre-resonant octet state. The trend as a function of Nch does not indicate any strong changes in ϒ(1S) production between low- and high-multiplicity pp col- lisions. The measurements are compatible with a non-negligible fraction of ϒ(2S) and ϒ(3S) mesons being produced via the trans- versely polarized 3 S[8] 1 octet term. Given the present uncertainties, Fig. 4. Two-dimensional marginals of the PPD for the HX frame in the λϕ vs. λϑ (top) and λϑϕ vs. λϕ (bottom) planes, for ϒ(2S) with 15 < pT < 35 GeV and 10 < Nch < 20, displaying the 68.3% and 99.7% CL total uncertainties. The shaded areas represent physically forbidden regions of parameter space for the decay of a J = 1 particle [14]. no clear trends can be seen regarding changes of their polariza- tions with Nch. To place these results into context, Fig. 6-top illustrates how the λϑ parameter would change as a function of Nch if quarkonium production would be dominated by two processes, one unpolar- ized (λϑ = 0, as is the case for the 1 S[8] 0 octet) and the other fully transversely polarized in the HX frame (λϑ = +1, as for the 3 S[8] 1 octet, at high enough pT). The four curves represent differ- ent variations with Nch (linearly in the 0 < Nch < 60 range) of the fraction of events, f , produced through the latter process (defined in the legends). These curves were computed knowing that the polarization of a sample of quarkonium states produced through two different processes, of polarizations λ0 and λ1, depends on f as [25] λ( f ) = [ (1 − f )λ0 3 + λ0 + f λ1 3 + λ1 ]/[ 1 − f 3 + λ0 + f 3 + λ1 ] . (4) The CMS Collaboration / Physics Letters B 761 (2016) 31–52 35 Fig. 5. The λϑ , λϕ , λϑϕ , and λ̃ parameters (top to bottom) for the ϒ(1S), ϒ(2S), and ϒ(3S) states (left to right), in the HX frame, as a function of Nch, for both pT ranges. The λ̃ values are also shown for the CS frame; the HX and CS uncertainties are strongly correlated. The vertical bars represent the Nch-dependent total uncertainties (at 68.3% CL), while the boxes at the zero horizontal line represent the global uncertainties. The points are placed at the average Nch of each bin, with a small offset for easier viewing. Changes in the LDMEs, in particular of the dominant 1 S[8] 0 and 3 S[8] 1 octet terms [7], are not the only possible cause of variations in the measured ϒ(nS) λ parameters between low- and high- multiplicity pp collisions; the effects of feed-down decays from heavier quarkonia should also be considered. In fact, the polar- izations reported here correspond to inclusive ϒ(nS) samples, not distinguishing mesons emitted in the decays of S- and P-wave bottomonium states from the directly-produced ones. Assuming that all directly-produced S-wave states have identical polariza- tions, their decays to lighter S-wave states do not induce differ- ences between the measured (inclusive) polarizations and those of the directly-produced mesons. On the contrary, feed-down de- cays from P-wave states can significantly affect the measured val- ues, especially for the ϒ(1S) state, presumably the one affected by the largest feed-down fraction. It is presently not possible to reliably evaluate the influence of the feed-down decays on the measured ϒ(nS) polarizations, for lack of information regarding the χb polarizations and their feed-down fractions. Fig. 6-bottom shows how the measured (inclusive) polarization is expected to change as a function of Nch if the directly-produced component (of polarization λ0) is complemented by a feed-down component (of polarization λ1) that contributes with a fraction f , decreasing linearly with Nch from 50% to 0 in the 0 < Nch < 60 range. The six curves correspond to different assumptions for λ0 and λ1, re- ported in the legends, with λ1 representing an effective average of the χb1 and χb2 polarizations (the χb1 and χb2 λϑ values must verify λϑ > −1/3 and λϑ > −3/5, respectively [25]). In these sce- narios the feed-down fraction is assumed to become negligible at high Nch, where the inclusive λϑ tends to the direct λ0 value. At low Nch, where the feed-down contribution is, hypothetically, the highest, the inclusive λϑ parameter crucially depends on the as- sumed χb polarization. 36 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 Fig. 6. Expected Nch-dependences of the λϑ parameter for the sum of two processes, of polarizations λ0 and λ1, of relative fractions changing linearly with Nch (see text for details). The measured λϑ values are also shown, for the ϒ(3S) (top) and ϒ(1S) (bottom). 5. Summary The polarizations of the ϒ(1S), ϒ(2S), and ϒ(3S) mesons pro- duced in pp collisions at √ s = 7 TeV have been determined as functions of the charged particle multiplicity of the event in two ϒ(nS) pT ranges. The measurements do not show significant vari- ations as a function of Nch, even though the large ϒ(2S) and ϒ(3S) uncertainties preclude definite statements in these cases. This study opens the way for analogous measurements extending to the charmonium family, particularly interesting for the ψ (2S), which is unaffected by feed-down decays and, therefore, provides a more direct probe of LDME universality. Equivalent analyses should also be performed in pPb and PbPb event samples, in view of eval- uating how quark–antiquark bound-state formation is influenced by the surrounding medium, which is an essential input for the interpretation of quarkonium suppression patterns in nuclear col- lisions. Acknowledgements We congratulate our colleagues in the CERN accelerator depart- ments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS in- stitutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construc- tion and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); F.R.S. - FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COL- CIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER, ERC IUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portu- gal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzer- land); MST (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thai- land); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie pro- gramme and the European Research Council and EPLANET (Euro- pean Union); the Leventis Foundation; the Alfred P. Sloan Founda- tion; the Alexander von Humboldt Foundation; the Belgian Fed- eral Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT- Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS programme of the Foundation for Pol- ish Science, cofinanced from European Union, Regional Develop- ment Fund; the OPUS programme of the National Science Cen- ter (Poland); the Compagnia di San Paolo (Torino); MIUR project 20108T4XTM (Italy); the Thalis and Aristeia programmes cofi- nanced by EU-ESF and the Greek NSRF; the National Priorities Re- search Program by Qatar National Research Fund; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn Univer- sity (Thailand); the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); and the Welch Founda- tion, contract C-1845. 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Xu State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China C. Avila, A. Cabrera, L.F. Chaparro Sierra, C. Florez, J.P. Gomez, B. Gomez Moreno, J.C. Sanabria Universidad de Los Andes, Bogota, Colombia N. Godinovic, D. Lelas, I. Puljak, P.M. Ribeiro Cipriano University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia Z. Antunovic, M. Kovac University of Split, Faculty of Science, Split, Croatia V. Brigljevic, K. Kadija, J. Luetic, S. Micanovic, L. Sudic Institute Rudjer Boskovic, Zagreb, Croatia A. Attikis, G. Mavromanolakis, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis, H. Rykaczewski The CMS Collaboration / Physics Letters B 761 (2016) 31–52 39 University of Cyprus, Nicosia, Cyprus M. Bodlak, M. Finger 9, M. Finger Jr. 9 Charles University, Prague, Czech Republic A.A. Abdelalim 10,11, A. Awad, A. Mahrous 10, A. Radi 12,13 Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt B. Calpas, M. Kadastik, M. Murumaa, M. Raidal, A. Tiko, C. Veelken National Institute of Chemical Physics and Biophysics, Tallinn, Estonia P. Eerola, J. Pekkanen, M. Voutilainen Department of Physics, University of Helsinki, Helsinki, Finland J. Härkönen, V. Karimäki, R. Kinnunen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, T. Peltola, J. Tuominiemi, E. Tuovinen, L. Wendland Helsinki Institute of Physics, Helsinki, Finland J. Talvitie, T. Tuuva Lappeenranta University of Technology, Lappeenranta, Finland M. Besancon, F. Couderc, M. Dejardin, D. Denegri, B. Fabbro, J.L. Faure, C. Favaro, F. Ferri, S. Ganjour, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, E. Locci, M. Machet, J. Malcles, J. Rander, A. Rosowsky, M. Titov, A. Zghiche DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France A. Abdulsalam, I. Antropov, S. 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Paktinat Mehdiabadi, F. Rezaei Hosseinabadi, B. Safarzadeh 29, M. Zeinali Institute for Research in Fundamental Sciences (IPM), Tehran, Iran M. Felcini, M. Grunewald University College Dublin, Dublin, Ireland M. Abbrescia a,b, C. Calabria a,b, C. Caputo a,b, A. Colaleo a, D. Creanza a,c, L. Cristella a,b, N. De Filippis a,c, M. De Palma a,b, L. Fiore a, G. Iaselli a,c, G. Maggi a,c, M. Maggi a, G. Miniello a,b, S. My a,c, S. Nuzzo a,b, A. Pompili a,b, G. Pugliese a,c, R. Radogna a,b, A. Ranieri a, G. Selvaggi a,b, L. Silvestris a,2, R. Venditti a,b a INFN Sezione di Bari, Bari, Italy b Università di Bari, Bari, Italy c Politecnico di Bari, Bari, Italy G. Abbiendi a, C. Battilana 2, D. Bonacorsi a,b, S. Braibant-Giacomelli a,b, L. Brigliadori a,b, R. Campanini a,b, P. Capiluppi a,b, A. Castro a,b, F.R. Cavallo a, S.S. Chhibra a,b, G. Codispoti a,b, M. Cuffiani a,b, G.M. Dallavalle a, F. Fabbri a, A. Fanfani a,b, D. Fasanella a,b, P. Giacomelli a, C. Grandi a, L. 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Song Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Republic of Korea S. Cho, S. Choi, Y. Go, D. Gyun, B. Hong, H. Kim, Y. Kim, B. Lee, K. Lee, K.S. Lee, S. Lee, J. Lim, S.K. Park, Y. Roh Korea University, Seoul, Republic of Korea H.D. Yoo Seoul National University, Seoul, Republic of Korea M. Choi, H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park, G. Ryu, M.S. Ryu University of Seoul, Seoul, Republic of Korea Y. Choi, J. Goh, D. Kim, E. Kwon, J. Lee, I. Yu Sungkyunkwan University, Suwon, Republic of Korea V. Dudenas, A. Juodagalvis, J. Vaitkus Vilnius University, Vilnius, Lithuania 44 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 I. Ahmed, Z.A. Ibrahim, J.R. Komaragiri, M.A.B. Md Ali 32, F. Mohamad Idris 33, W.A.T. Wan Abdullah, M.N. Yusli, Z. Zolkapli National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia E. Casimiro Linares, H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-De La Cruz 34, A. Hernandez-Almada, R. Lopez-Fernandez, J. Mejia Guisao, A. Sanchez-Hernandez Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico S. Carrillo Moreno, F. Vazquez Valencia Universidad Iberoamericana, Mexico City, Mexico I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada Benemerita Universidad Autonoma de Puebla, Puebla, Mexico A. Morelos Pineda Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico D. Krofcheck University of Auckland, Auckland, New Zealand P.H. Butler University of Canterbury, Christchurch, New Zealand A. Ahmad, M. Ahmad, Q. Hassan, H.R. Hoorani, W.A. Khan, T. Khurshid, M. Shoaib, M. Waqas National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan H. Bialkowska, M. Bluj, B. Boimska, T. Frueboes, M. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, P. Zalewski National Centre for Nuclear Research, Swierk, Poland G. Brona, K. Bunkowski, A. Byszuk 35, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski, M. Misiura, M. Olszewski, M. Walczak Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland P. Bargassa, C. Beirão Da Cruz E Silva, A. Di Francesco, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, J. Hollar, N. Leonardo, L. Lloret Iglesias, F. Nguyen, J. Rodrigues Antunes, J. Seixas, O. Toldaiev, D. Vadruccio, J. Varela, P. Vischia Laboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal S. Afanasiev, P. Bunin, M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin, A. Lanev, A. Malakhov, V. Matveev 36,37, P. Moisenz, V. Palichik, V. Perelygin, S. Shmatov, S. Shulha, N. Skatchkov, V. Smirnov, A. Zarubin Joint Institute for Nuclear Research, Dubna, Russia V. Golovtsov, Y. Ivanov, V. Kim 38, E. Kuznetsova, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, A. Karneyeu, M. Kirsanov, N. Krasnikov, A. Pashenkov, D. Tlisov, A. Toropin Institute for Nuclear Research, Moscow, Russia The CMS Collaboration / Physics Letters B 761 (2016) 31–52 45 V. Epshteyn, V. Gavrilov, N. Lychkovskaya, V. Popov, I. Pozdnyakov, G. Safronov, A. Spiridonov, E. Vlasov, A. Zhokin Institute for Theoretical and Experimental Physics, Moscow, Russia M. Chadeeva, R. Chistov, M. Danilov, V. Rusinov, E. Tarkovskii National Research Nuclear University ‘Moscow Engineering Physics Institute’ (MEPhI), Moscow, Russia V. Andreev, M. Azarkin 37, I. Dremin 37, M. Kirakosyan, A. Leonidov 37, G. Mesyats, S.V. Rusakov P.N. Lebedev Physical Institute, Moscow, Russia A. Baskakov, A. Belyaev, E. Boos, A. Demiyanov, A. Ershov, A. Gribushin, O. Kodolova, V. Korotkikh, I. Lokhtin, I. Miagkov, S. Obraztsov, S. Petrushanko, V. Savrin, A. Snigirev, I. Vardanyan Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia I. Azhgirey, I. Bayshev, S. Bitioukov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine, V. Petrov, R. Ryutin, A. Sobol, L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia P. Adzic 39, P. Cirkovic, D. Devetak, J. Milosevic, V. Rekovic University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia J. Alcaraz Maestre, E. Calvo, M. Cerrada, M. Chamizo Llatas, N. Colino, B. De La Cruz, A. Delgado Peris, A. Escalante Del Valle, C. Fernandez Bedoya, J.P. Fernández Ramos, J. Flix, M.C. Fouz, P. Garcia-Abia, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, E. Navarro De Martino, A. Pérez-Calero Yzquierdo, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, J. Santaolalla, M.S. Soares Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain C. Albajar, J.F. de Trocóniz, M. Missiroli, D. Moran Universidad Autónoma de Madrid, Madrid, Spain J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, E. Palencia Cortezon, J.M. Vizan Garcia Universidad de Oviedo, Oviedo, Spain I.J. Cabrillo, A. Calderon, J.R. Castiñeiras De Saa, E. Curras, P. De Castro Manzano, M. Fernandez, J. Garcia-Ferrero, G. Gomez, A. Lopez Virto, J. Marco, R. Marco, C. Martinez Rivero, F. Matorras, J. Piedra Gomez, T. Rodrigo, A.Y. Rodríguez-Marrero, A. Ruiz-Jimeno, L. Scodellaro, N. Trevisani, I. Vila, R. Vilar Cortabitarte Instituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain D. Abbaneo, E. Auffray, G. Auzinger, M. Bachtis, P. Baillon, A.H. Ball, D. Barney, A. Benaglia, J. Bendavid, L. Benhabib, G.M. Berruti, P. Bloch, A. Bocci, A. Bonato, C. Botta, H. Breuker, T. Camporesi, R. Castello, G. Cerminara, M. D’Alfonso, D. d’Enterria, A. Dabrowski, V. Daponte, A. David, M. De Gruttola, F. De Guio, A. De Roeck, S. De Visscher, E. Di Marco 40, M. Dobson, M. Dordevic, B. Dorney, T. du Pree, D. Duggan, M. Dünser, N. Dupont, A. Elliott-Peisert, G. Franzoni, J. Fulcher, W. Funk, D. Gigi, K. Gill, D. Giordano, M. Girone, F. Glege, R. Guida, S. Gundacker, M. Guthoff, J. Hammer, P. Harris, J. Hegeman, V. Innocente, P. Janot, H. Kirschenmann, M.J. Kortelainen, K. Kousouris, K. Krajczar, P. Lecoq, C. Lourenço, M.T. Lucchini, N. Magini, L. Malgeri, M. Mannelli, A. Martelli, L. Masetti, F. Meijers, S. Mersi, E. Meschi, F. Moortgat, S. Morovic, M. Mulders, M.V. Nemallapudi, H. Neugebauer, S. Orfanelli 41, L. Orsini, L. Pape, E. Perez, M. Peruzzi, A. Petrilli, G. Petrucciani, A. Pfeiffer, M. Pierini, D. Piparo, A. Racz, T. Reis, G. Rolandi 42, M. Rovere, M. Ruan, H. Sakulin, C. Schäfer, C. Schwick, M. Seidel, A. Sharma, P. Silva, M. Simon, 46 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 P. Sphicas 43, J. Steggemann, B. Stieger, M. Stoye, Y. Takahashi, D. Treille, A. Triossi, A. Tsirou, G.I. Veres 20, N. Wardle, H.K. Wöhri, A. 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Salerno, Y. Yang Universität Zürich, Zurich, Switzerland M. Cardaci, K.H. Chen, T.H. Doan, Sh. Jain, R. Khurana, M. Konyushikhin, C.M. Kuo, W. Lin, Y.J. Lu, A. Pozdnyakov, S.S. Yu National Central University, Chung-Li, Taiwan Arun Kumar, P. Chang, Y.H. Chang, Y.W. Chang, Y. Chao, K.F. Chen, P.H. Chen, C. Dietz, F. Fiori, U. Grundler, W.-S. Hou, Y. Hsiung, Y.F. Liu, R.-S. Lu, M. Miñano Moya, E. Petrakou, J.f. Tsai, Y.M. Tzeng National Taiwan University (NTU), Taipei, Taiwan B. Asavapibhop, K. Kovitanggoon, G. Singh, N. Srimanobhas, N. Suwonjandee Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand A. Adiguzel, S. Cerci 46, S. Damarseckin, Z.S. Demiroglu, C. Dozen, I. Dumanoglu, S. Girgis, G. Gokbulut, Y. Guler, E. Gurpinar, I. Hos, E.E. Kangal 47, A. Kayis Topaksu, G. Onengut 48, K. Ozdemir 49, A. Polatoz, B. Tali 46, H. Topakli 50, C. Zorbilmez Cukurova University, Adana, Turkey B. Bilin, S. Bilmis, B. Isildak 51, G. Karapinar 52, M. Yalvac, M. Zeyrek Middle East Technical University, Physics Department, Ankara, Turkey E. Gülmez, M. Kaya 53, O. Kaya 54, E.A. Yetkin 55, T. Yetkin 56 Bogazici University, Istanbul, Turkey A. Cakir, K. Cankocak, S. Sen 57, F.I. Vardarlı Istanbul Technical University, Istanbul, Turkey B. Grynyov Institute for Scintillation Materials of National Academy of Science of Ukraine, Kharkov, Ukraine L. Levchuk, P. Sorokin National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine The CMS Collaboration / Physics Letters B 761 (2016) 31–52 47 R. Aggleton, F. Ball, L. Beck, J.J. Brooke, E. Clement, D. Cussans, H. Flacher, J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath, J. Jacob, L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold 58, S. Paramesvaran, A. Poll, T. Sakuma, S. Seif El Nasr-storey, S. Senkin, D. Smith, V.J. Smith University of Bristol, Bristol, United Kingdom A. Belyaev 59, C. Brew, R.M. Brown, L. Calligaris, D. Cieri, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, E. Olaiya, D. Petyt, C.H. Shepherd-Themistocleous, A. Thea, I.R. Tomalin, T. Williams, S.D. Worm Rutherford Appleton Laboratory, Didcot, United Kingdom M. Baber, R. Bainbridge, O. Buchmuller, A. Bundock, D. Burton, S. Casasso, M. Citron, D. Colling, L. Corpe, P. Dauncey, G. Davies, A. De Wit, M. Della Negra, P. Dunne, A. Elwood, D. Futyan, G. Hall, G. Iles, R. Lane, R. Lucas 58, L. Lyons, A.-M. Magnan, S. Malik, J. Nash, A. Nikitenko 44, J. Pela, M. Pesaresi, D.M. Raymond, A. Richards, A. Rose, C. Seez, A. Tapper, K. Uchida, M. Vazquez Acosta 60, T. Virdee, S.C. Zenz Imperial College, London, United Kingdom J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, D. Leslie, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner Brunel University, Uxbridge, United Kingdom A. Borzou, K. Call, J. Dittmann, K. Hatakeyama, H. Liu, N. Pastika Baylor University, Waco, USA O. Charaf, S.I. Cooper, C. Henderson, P. Rumerio The University of Alabama, Tuscaloosa, USA D. Arcaro, A. Avetisyan, T. Bose, D. Gastler, D. Rankin, C. Richardson, J. Rohlf, L. Sulak, D. Zou Boston University, Boston, USA J. Alimena, G. Benelli, E. Berry, D. Cutts, A. Ferapontov, A. Garabedian, J. Hakala, U. Heintz, O. Jesus, E. Laird, G. Landsberg, Z. Mao, M. Narain, S. Piperov, S. Sagir, R. Syarif Brown University, Providence, USA R. Breedon, G. Breto, M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher, G. Funk, M. Gardner, W. Ko, R. Lander, C. Mclean, M. Mulhearn, D. Pellett, J. Pilot, F. Ricci-Tam, S. Shalhout, J. Smith, M. Squires, D. Stolp, M. Tripathi, S. Wilbur, R. Yohay University of California, Davis, Davis, USA R. Cousins, P. Everaerts, A. Florent, J. Hauser, M. Ignatenko, D. Saltzberg, E. Takasugi, V. Valuev, M. Weber University of California, Los Angeles, USA K. Burt, R. Clare, J. Ellison, J.W. Gary, G. Hanson, J. Heilman, M. Ivova PANEVA, P. Jandir, E. Kennedy, F. Lacroix, O.R. Long, M. Malberti, M. Olmedo Negrete, A. Shrinivas, H. Wei, S. Wimpenny, B.R. Yates University of California, Riverside, Riverside, USA J.G. Branson, G.B. Cerati, S. Cittolin, R.T. D’Agnolo, M. Derdzinski, A. Holzner, R. Kelley, D. Klein, J. Letts, I. Macneill, D. Olivito, S. Padhi, M. Pieri, M. Sani, V. Sharma, S. Simon, M. Tadel, A. Vartak, S. Wasserbaech 61, C. Welke, F. Würthwein, A. Yagil, G. Zevi Della Porta University of California, San Diego, La Jolla, USA J. Bradmiller-Feld, C. Campagnari, A. Dishaw, V. Dutta, K. Flowers, M. Franco Sevilla, P. Geffert, C. George, F. Golf, L. Gouskos, J. Gran, J. Incandela, N. Mccoll, S.D. Mullin, J. Richman, D. Stuart, I. Suarez, C. West, J. Yoo 48 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 University of California, Santa Barbara, Santa Barbara, USA D. Anderson, A. Apresyan, A. Bornheim, J. Bunn, Y. Chen, J. Duarte, A. Mott, H.B. Newman, C. Pena, M. Spiropulu, J.R. Vlimant, S. Xie, R.Y. Zhu California Institute of Technology, Pasadena, USA M.B. Andrews, V. Azzolini, A. Calamba, B. Carlson, T. Ferguson, M. Paulini, J. Russ, M. Sun, H. Vogel, I. Vorobiev Carnegie Mellon University, Pittsburgh, USA J.P. Cumalat, W.T. Ford, A. Gaz, F. Jensen, A. Johnson, M. Krohn, T. Mulholland, U. Nauenberg, K. Stenson, S.R. Wagner University of Colorado Boulder, Boulder, USA J. Alexander, A. Chatterjee, J. Chaves, J. Chu, S. Dittmer, N. Eggert, N. Mirman, G. Nicolas Kaufman, J.R. Patterson, A. Rinkevicius, A. Ryd, L. Skinnari, L. Soffi, W. Sun, S.M. Tan, W.D. Teo, J. Thom, J. Thompson, J. Tucker, Y. Weng, P. Wittich Cornell University, Ithaca, USA S. Abdullin, M. Albrow, G. Apollinari, S. Banerjee, L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, G. Bolla, K. Burkett, J.N. Butler, H.W.K. Cheung, F. Chlebana, S. Cihangir, V.D. Elvira, I. Fisk, J. Freeman, E. Gottschalk, L. Gray, D. Green, S. Grünendahl, O. Gutsche, J. Hanlon, D. Hare, R.M. Harris, S. Hasegawa, J. Hirschauer, Z. Hu, B. Jayatilaka, S. Jindariani, M. Johnson, U. Joshi, B. Klima, B. Kreis, S. Lammel, J. Lewis, J. Linacre, D. Lincoln, R. Lipton, T. Liu, R. Lopes De Sá, J. Lykken, K. Maeshima, J.M. Marraffino, S. Maruyama, D. Mason, P. McBride, P. Merkel, S. Mrenna, S. Nahn, C. Newman-Holmes †, V. O’Dell, K. Pedro, O. Prokofyev, G. Rakness, E. Sexton-Kennedy, A. Soha, W.J. Spalding, L. Spiegel, S. Stoynev, N. Strobbe, L. Taylor, S. Tkaczyk, N.V. Tran, L. Uplegger, E.W. Vaandering, C. Vernieri, M. Verzocchi, R. Vidal, M. Wang, H.A. Weber, A. Whitbeck Fermi National Accelerator Laboratory, Batavia, USA D. Acosta, P. Avery, P. Bortignon, D. Bourilkov, A. Brinkerhoff, A. Carnes, M. Carver, D. Curry, S. Das, R.D. Field, I.K. Furic, J. Konigsberg, A. Korytov, K. Kotov, P. Ma, K. Matchev, H. Mei, P. Milenovic 62, G. Mitselmakher, D. Rank, R. Rossin, L. Shchutska, M. Snowball, D. Sperka, N. Terentyev, L. Thomas, J. Wang, S. Wang, J. Yelton University of Florida, Gainesville, USA S. Hewamanage, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez Florida International University, Miami, USA A. Ackert, J.R. Adams, T. Adams, A. Askew, S. Bein, J. Bochenek, B. Diamond, J. Haas, S. Hagopian, V. Hagopian, K.F. Johnson, A. Khatiwada, H. Prosper, M. Weinberg Florida State University, Tallahassee, USA M.M. Baarmand, V. Bhopatkar, S. Colafranceschi 63, M. Hohlmann, H. Kalakhety, D. Noonan, T. Roy, F. Yumiceva Florida Institute of Technology, Melbourne, USA M.R. Adams, L. Apanasevich, D. Berry, R.R. Betts, I. Bucinskaite, R. Cavanaugh, O. Evdokimov, L. Gauthier, C.E. Gerber, D.J. Hofman, P. Kurt, C. O’Brien, I.D. Sandoval Gonzalez, P. Turner, N. Varelas, Z. Wu, M. Zakaria, J. Zhang University of Illinois at Chicago (UIC), Chicago, USA The CMS Collaboration / Physics Letters B 761 (2016) 31–52 49 B. Bilki 64, W. Clarida, K. Dilsiz, S. Durgut, R.P. Gandrajula, M. Haytmyradov, V. Khristenko, J.-P. Merlo, H. Mermerkaya 65, A. Mestvirishvili, A. Moeller, J. Nachtman, H. Ogul, Y. Onel, F. Ozok 66, A. Penzo, C. Snyder, E. Tiras, J. Wetzel, K. Yi The University of Iowa, Iowa City, USA I. Anderson, B.A. Barnett, B. Blumenfeld, A. Cocoros, N. Eminizer, D. Fehling, L. Feng, A.V. Gritsan, P. Maksimovic, M. Osherson, J. Roskes, U. Sarica, M. Swartz, M. Xiao, Y. Xin, C. You Johns Hopkins University, Baltimore, USA P. Baringer, A. Bean, C. Bruner, R.P. Kenny III, D. Majumder, M. Malek, W. Mcbrayer, M. Murray, S. Sanders, R. Stringer, Q. Wang The University of Kansas, Lawrence, USA A. Ivanov, K. Kaadze, S. Khalil, M. Makouski, Y. Maravin, A. Mohammadi, L.K. Saini, N. Skhirtladze, S. Toda Kansas State University, Manhattan, USA D. Lange, F. Rebassoo, D. Wright Lawrence Livermore National Laboratory, Livermore, USA C. Anelli, A. Baden, O. Baron, A. Belloni, B. Calvert, S.C. Eno, C. Ferraioli, J.A. Gomez, N.J. Hadley, S. Jabeen, R.G. Kellogg, T. Kolberg, J. Kunkle, Y. Lu, A.C. Mignerey, Y.H. Shin, A. Skuja, M.B. Tonjes, S.C. Tonwar University of Maryland, College Park, USA A. Apyan, R. Barbieri, A. Baty, R. Bi, K. Bierwagen, S. Brandt, W. Busza, I.A. Cali, Z. Demiragli, L. Di Matteo, G. Gomez Ceballos, M. Goncharov, D. Gulhan, Y. Iiyama, G.M. Innocenti, M. Klute, D. Kovalskyi, Y.S. Lai, Y.-J. Lee, A. Levin, P.D. Luckey, A.C. Marini, C. Mcginn, C. Mironov, S. Narayanan, X. Niu, C. Paus, C. Roland, G. Roland, J. Salfeld-Nebgen, G.S.F. Stephans, K. Sumorok, K. Tatar, M. Varma, D. Velicanu, J. Veverka, J. Wang, T.W. Wang, B. Wyslouch, M. Yang, V. Zhukova Massachusetts Institute of Technology, Cambridge, USA A.C. Benvenuti, B. Dahmes, A. Evans, A. Finkel, A. Gude, P. Hansen, S. Kalafut, S.C. Kao, K. Klapoetke, Y. Kubota, Z. Lesko, J. Mans, S. Nourbakhsh, N. Ruckstuhl, R. Rusack, N. Tambe, J. Turkewitz University of Minnesota, Minneapolis, USA J.G. Acosta, S. Oliveros University of Mississippi, Oxford, USA E. Avdeeva, R. Bartek, K. Bloom, S. Bose, D.R. Claes, A. Dominguez, C. Fangmeier, R. Gonzalez Suarez, R. Kamalieddin, D. Knowlton, I. Kravchenko, F. Meier, J. Monroy, F. Ratnikov, J.E. Siado, G.R. Snow University of Nebraska–Lincoln, Lincoln, USA M. Alyari, J. Dolen, J. George, A. Godshalk, C. Harrington, I. Iashvili, J. Kaisen, A. Kharchilava, A. Kumar, S. Rappoccio, B. Roozbahani State University of New York at Buffalo, Buffalo, USA G. Alverson, E. Barberis, D. Baumgartel, M. Chasco, A. Hortiangtham, A. Massironi, D.M. Morse, D. Nash, T. Orimoto, R. Teixeira De Lima, D. Trocino, R.-J. Wang, D. Wood, J. Zhang Northeastern University, Boston, USA 50 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 S. Bhattacharya, K.A. Hahn, A. Kubik, J.F. Low, N. Mucia, N. Odell, B. Pollack, M. Schmitt, K. Sung, M. Trovato, M. Velasco Northwestern University, Evanston, USA N. Dev, M. Hildreth, C. Jessop, D.J. Karmgard, N. Kellams, K. Lannon, N. Marinelli, F. Meng, C. Mueller, Y. Musienko 36, M. Planer, A. Reinsvold, R. Ruchti, G. Smith, S. Taroni, N. Valls, M. Wayne, M. Wolf, A. Woodard University of Notre Dame, Notre Dame, USA L. Antonelli, J. Brinson, B. Bylsma, L.S. Durkin, S. Flowers, A. Hart, C. Hill, R. Hughes, W. Ji, T.Y. Ling, B. Liu, W. Luo, D. Puigh, M. Rodenburg, B.L. Winer, H.W. Wulsin The Ohio State University, Columbus, USA O. Driga, P. Elmer, J. Hardenbrook, P. Hebda, S.A. Koay, P. Lujan, D. Marlow, T. Medvedeva, M. Mooney, J. Olsen, C. Palmer, P. Piroué, D. Stickland, C. Tully, A. Zuranski Princeton University, Princeton, USA S. Malik University of Puerto Rico, Mayaguez, USA A. Barker, V.E. Barnes, D. Benedetti, D. Bortoletto, L. Gutay, M.K. Jha, M. Jones, A.W. Jung, K. Jung, A. Kumar, D.H. Miller, N. Neumeister, B.C. Radburn-Smith, X. Shi, I. Shipsey, D. Silvers, J. Sun, A. Svyatkovskiy, F. Wang, W. Xie, L. Xu Purdue University, West Lafayette, USA N. Parashar, J. Stupak Purdue University Calumet, Hammond, USA A. Adair, B. Akgun, Z. Chen, K.M. Ecklund, F.J.M. Geurts, M. Guilbaud, W. Li, B. Michlin, M. Northup, B.P. Padley, R. Redjimi, J. Roberts, J. Rorie, Z. Tu, J. Zabel Rice University, Houston, USA B. Betchart, A. Bodek, P. de Barbaro, R. Demina, Y. Eshaq, T. Ferbel, M. Galanti, A. Garcia-Bellido, J. Han, O. Hindrichs, A. Khukhunaishvili, K.H. Lo, P. Tan, M. Verzetti University of Rochester, Rochester, USA J.P. Chou, E. Contreras-Campana, D. Ferencek, Y. Gershtein, E. Halkiadakis, M. Heindl, D. Hidas, E. Hughes, S. Kaplan, R. Kunnawalkam Elayavalli, A. Lath, K. Nash, H. Saka, S. Salur, S. Schnetzer, D. Sheffield, S. Somalwar, R. Stone, S. Thomas, P. Thomassen, M. Walker Rutgers, The State University of New Jersey, Piscataway, USA M. Foerster, G. Riley, K. Rose, S. Spanier, K. Thapa University of Tennessee, Knoxville, USA O. Bouhali 67, A. Castaneda Hernandez 67, A. Celik, M. Dalchenko, M. De Mattia, A. Delgado, S. Dildick, R. Eusebi, J. Gilmore, T. Huang, T. Kamon 68, V. Krutelyov, R. Mueller, I. Osipenkov, Y. Pakhotin, R. Patel, A. Perloff, A. Rose, A. Safonov, A. Tatarinov, K.A. Ulmer 2 Texas A&M University, College Station, USA N. Akchurin, C. Cowden, J. Damgov, C. Dragoiu, P.R. Dudero, J. Faulkner, S. Kunori, K. Lamichhane, S.W. Lee, T. Libeiro, S. Undleeb, I. Volobouev The CMS Collaboration / Physics Letters B 761 (2016) 31–52 51 Texas Tech University, Lubbock, USA E. Appelt, A.G. Delannoy, S. Greene, A. Gurrola, R. Janjam, W. Johns, C. Maguire, Y. Mao, A. Melo, H. Ni, P. Sheldon, S. Tuo, J. Velkovska, Q. Xu Vanderbilt University, Nashville, USA M.W. Arenton, B. Cox, B. Francis, J. Goodell, R. Hirosky, A. Ledovskoy, H. Li, C. Lin, C. Neu, T. Sinthuprasith, X. Sun, Y. Wang, E. Wolfe, J. Wood, F. Xia University of Virginia, Charlottesville, USA C. Clarke, R. Harr, P.E. Karchin, C. Kottachchi Kankanamge Don, P. Lamichhane, J. Sturdy Wayne State University, Detroit, USA D.A. Belknap, D. Carlsmith, M. Cepeda, S. Dasu, L. Dodd, S. Duric, B. Gomber, M. Grothe, M. Herndon, A. Hervé, P. Klabbers, A. Lanaro, A. Levine, K. Long, R. Loveless, A. Mohapatra, I. Ojalvo, T. Perry, G.A. Pierro, G. Polese, T. Ruggles, T. Sarangi, A. Savin, A. Sharma, N. Smith, W.H. Smith, D. Taylor, P. Verwilligen, N. Woods University of Wisconsin–Madison, Madison, WI, USA † Deceased. 1 Also at Vienna University of Technology, Vienna, Austria. 2 Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland. 3 Also at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China. 4 Also at Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France. 5 Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia. 6 Also at Universidade Estadual de Campinas, Campinas, Brazil. 7 Also at Centre National de la Recherche Scientifique (CNRS) – IN2P3, Paris, France. 8 Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France. 9 Also at Joint Institute for Nuclear Research, Dubna, Russia. 10 Also at Helwan University, Cairo, Egypt. 11 Now at Zewail City of Science and Technology, Zewail, Egypt. 12 Also at British University in Egypt, Cairo, Egypt. 13 Now at Ain Shams University, Cairo, Egypt. 14 Also at Université de Haute Alsace, Mulhouse, France. 15 Also at Tbilisi State University, Tbilisi, Georgia. 16 Also at RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany. 17 Also at University of Hamburg, Hamburg, Germany. 18 Also at Brandenburg University of Technology, Cottbus, Germany. 19 Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary. 20 Also at Eötvös Loránd University, Budapest, Hungary. 21 Also at University of Debrecen, Debrecen, Hungary. 22 Also at Wigner Research Centre for Physics, Budapest, Hungary. 23 Also at Indian Institute of Science Education and Research, Bhopal, India. 24 Also at University of Visva-Bharati, Santiniketan, India. 25 Now at King Abdulaziz University, Jeddah, Saudi Arabia. 26 Also at University of Ruhuna, Matara, Sri Lanka. 27 Also at Isfahan University of Technology, Isfahan, Iran. 28 Also at University of Tehran, Department of Engineering Science, Tehran, Iran. 29 Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran. 30 Also at Università degli Studi di Siena, Siena, Italy. 31 Also at Purdue University, West Lafayette, USA. 32 Also at International Islamic University of Malaysia, Kuala Lumpur, Malaysia. 33 Also at Malaysian Nuclear Agency, MOSTI, Kajang, Malaysia. 34 Also at Consejo Nacional de Ciencia y Tecnología, Mexico city, Mexico. 35 Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland. 36 Also at Institute for Nuclear Research, Moscow, Russia. 37 Now at National Research Nuclear University ‘Moscow Engineering Physics Institute’ (MEPhI), Moscow, Russia. 38 Also at St. Petersburg State Polytechnical University, St. Petersburg, Russia. 39 Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia. 40 Also at INFN Sezione di Roma; Università di Roma, Roma, Italy. 41 Also at National Technical University of Athens, Athens, Greece. 42 Also at Scuola Normale e Sezione dell’INFN, Pisa, Italy. 43 Also at National and Kapodistrian University of Athens, Athens, Greece. 52 The CMS Collaboration / Physics Letters B 761 (2016) 31–52 44 Also at Institute for Theoretical and Experimental Physics, Moscow, Russia. 45 Also at Albert Einstein Center for Fundamental Physics, Bern, Switzerland. 46 Also at Adiyaman University, Adiyaman, Turkey. 47 Also at Mersin University, Mersin, Turkey. 48 Also at Cag University, Mersin, Turkey. 49 Also at Piri Reis University, Istanbul, Turkey. 50 Also at Gaziosmanpasa University, Tokat, Turkey. 51 Also at Ozyegin University, Istanbul, Turkey. 52 Also at Izmir Institute of Technology, Izmir, Turkey. 53 Also at Marmara University, Istanbul, Turkey. 54 Also at Kafkas University, Kars, Turkey. 55 Also at Istanbul Bilgi University, Istanbul, Turkey. 56 Also at Yildiz Technical University, Istanbul, Turkey. 57 Also at Hacettepe University, Ankara, Turkey. 58 Also at Rutherford Appleton Laboratory, Didcot, United Kingdom. 59 Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom. 60 Also at Instituto de Astrofísica de Canarias, La Laguna, Spain. 61 Also at Utah Valley University, Orem, USA. 62 Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia. 63 Also at Facoltà Ingegneria, Università di Roma, Roma, Italy. 64 Also at Argonne National Laboratory, Argonne, USA. 65 Also at Erzincan University, Erzincan, Turkey. 66 Also at Mimar Sinan University, Istanbul, Istanbul, Turkey. 67 Also at Texas A&M University at Qatar, Doha, Qatar. 68 Also at Kyungpook National University, Daegu, Republic of Korea. Υ(nS) polarizations versus particle multiplicity in pp collisions at √s = 7 TeV 1 Introduction 2 CMS detector and data analysis 3 Extraction of the polarization parameters 4 Results 5 Summary Acknowledgements Appendix A Supplementary material References The CMS Collaboration