Browsing by Subject "PP"

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  • The ALICE collaboration; Acharya, S.; Brücken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Parkkila, J. E.; Rak, J.; Räsänen, S. S.; Saarinen, S.; Slupecki, M.; Snellman, T. W.; Trzaska, W. H.; Vargyas, M.; Viinikainen, J. (2019)
    Charged-particle spectra at midrapidity are measured in Pb-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair root s(NN) = 5.02 TeV and presented in centrality classes ranging from most central (0-5%) to most peripheral (95-100%) collisions. Possible medium effects are quantified using the nuclear modification factor (R-AA) by comparing the measured spectra with those from proton-proton collisions, scaled by the number of independent nucleon-nucleon collisions obtained from a Glauber model. At large transverse momenta (8 < p(T) < 20 GeV/c), the average R-AA is found to increase from about 0.15 in 0-5% central to a maximum value of about 0.8 in 75-85% peripheral collisions, beyond which it falls off strongly to below 0.2 for the most peripheral collisions. Furthermore, R-AA initially exhibits a positive slope as a function of p(T) in the 8-20 GeV/c interval, while for collisions beyond the 80% class the slope is negative. To reduce uncertainties related to event selection and normalization, we also provide the ratio of R-AA in adjacent centrality intervals. Our results in peripheral collisions are consistent with a PYTHIA-based model without nuclear modification, demonstrating that biases caused by the event selection and collision geometry can lead to the apparent suppression in peripheral collisions. This explains the unintuitive observation that R-AA is below unity in peripheral Pb-Pb, but equal to unity in minimum-bias p-Pb collisions despite similar charged-particle multiplicities. (C) 2019 Conseil Europeen pour la Recherche Nucleaire. Published by Elsevier B.V.
  • The CMS collaboration; Sirunyan, A. M.; Eerola, P.; Kirschenmann, H.; Pekkanen, J.; Voutilainen, M.; Havukainen, J.; Heikkilä, J. K.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampen, T.; Lassila-Perini, K.; Laurila, S.; Lehti, S.; Linden, T.; Luukka, P.; Mäenpää, T.; Siikonen, H.; Tuominen, E.; Tuominiemi, J.; Tuuva, T. (2020)
    Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at s = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at s = 7 TeV, as well as with theoretical predictions.
  • The ALICE collaboration; Acharya, S.; Brücken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Parkkila, J. E.; Rak, J.; Räsänen, S. S.; Saarinen, S.; Slupecki, M.; Snellman, T. W.; Trzaska, W. H.; Vargyas, M.; Viinikainen, J. (2019)
    In this Letter, the ALICE Collaboration presents the first measurements of the charged-particle multiplicity density, dN(ch)/d eta, and total charged-particle multiplicity, N-ch(tot), in Xe-Xe collisions at a centre-of-mass energy per nucleon-nucleon pair of root s(NN) = 5.44 TeV. The measurements are performed as a function of collision centrality over a wide pseudorapidity range of -3.5 < eta < 5. The values of dN(ch)/d eta at mid-rapidity and N-ch(tot) for central collisions, normalised to the number of nucleons participating in the collision (N-part) as a function of root s(NN) follow the trends established in previous heavy-ion measurements. The same quantities are also found to increase as a function of N-part, and up to the 5% most central collisions the trends are the same as the ones observed in Pb-Pb at a similar energy. For more central collisions, the Xe-Xe scaled multiplicities exceed those in Pb-Pb for a similar N-part. The results are compared to phenomenological models and theoretical calculations based on different mechanisms for particle production in nuclear collisions. All considered models describe the data reasonably well within 15%. (C) 2018 Published by Elsevier B.V.
  • Adam, J.; Brucken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Kral, J.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; The ALICE collaboration (2015)
    The nuclear modification factor, R-AA, of the prompt charmed mesons D-0, D+ and D*+, and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at a centre-of-mass energy root s(NN) = 2 : 76 TeV in two transverse momentum intervals, 5 <p(T) <8 GeV/c and 8 <p(T) <16 GeV/c, and in six collision centrality classes. The R-AA shows a maximum suppression of a factor of 5{6 in the 10% most central collisions. The suppression and its centrality dependence are compatible within uncertainties with those of charged pions. A comparison with the R-AA of non-prompt J/psi from B meson decays, measured by the CMS Collaboration, hints at a larger suppression of D mesons in the most central collisions.
  • Adam, J.; Brucken, E. J.; Chang, B.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; Viinikainen, J.; The ALICE collaboration (2017)
    We present the charged-particle pseudorapidity density in Pb-Pb collisions at root s(NN) = 5.02 TeV in centrality classes measured by ALICE. The measurement covers a wide pseudorapidity range from -3.5 to 5, which is sufficient for reliable estimates of the total number of charged particles produced in the collisions. For the most central (0-5%) collisions we find 21 400 +/- 1 300, while for the most peripheral (80-90%) we find 230 +/- 38. This corresponds to an increase of (27 +/- 4)% over the results at root s(NN) = 2.76 TeV previously reported by ALICE. The energy dependence of the total number of charged particles produced in heavy-ion collisions is found to obey a modified power-law like behaviour. The charged-particle pseudorapidity density of the most central collisions is compared to model calculations-none of which fully describes the measured distribution. We also present an estimate of the rapidity density of charged particles. The width of that distribution is found to exhibit a remarkable proportionality to the beam rapidity, independent of the collision energy from the top SPS to LHC energies. (C) 2017 The Author(s). Published by Elsevier B.V.
  • The ALICE collaboration; Acharya, S.; Brücken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Parkkila, J. E.; Rak, J.; Räsänen, S. S.; Saarinen, S.; Slupecki, M.; Snellman, T. W.; Trzaska, W. H.; Vargyas, M.; Viinikainen, J. (2019)
    Measurements of inclusive and direct photon production at midrapidity in pp collisions at root s = 2.76 and 8 TeV are presented by the ALICE experiment at the LHC. The results are reported in transverse momentum ranges of 0.4 < p(T) < 10 GeV/c and 0.3 < p(T) < 16 GeV/c, respectively. Photons are detected with the electromagnetic calorimeter (EMCal) and via reconstruction of e(+) e(-) pairs from conversions in the ALICE detector material using the central tracking system. For the final measurement of the inclusive photon spectra the results are combined in the overlapping p(T), interval of both methods. Direct photon spectra, or their upper limits at 90% C.L. are extracted using the direct photon excess ratio R-gamma, which quantifies the ratio of inclusive photons over decay photons generated with a decay-photon simulation. An additional hybrid method, combining photons reconstructed from conversions with those identified in the EMCal, is used for the combination of the direct photon excess ratio R-gamma, as well as the extraction of direct photon spectra or their upper limits. While no significant signal of direct photons is seen over the full p(T), range, R-gamma, for p(T), > 7 GeV/c is at least one sigma above unity and consistent with expectations from next-to-leading order pQCD calculations.
  • Adam, J.; Brucken, E. J.; Chang, B.; Kim, D. J.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; Viinikainen, J.; The ALICE collaboration (2017)
    In two-particle angular correlation measurements, jets give rise to a near-side peak, formed by particles associated to a higher-p(T) trigger particle. Measurements of these correlations as a function of pseudorapidity (Delta eta) and azimuthal (Delta phi) differences are used to extract the centrality and p(T) dependence of the shape of the near-side peak in the p(T) range 1 <p(T) <8 GeV/c in Pb-Pb and pp collisions at root s(NN) = 2.76 TeV. A combined fit of the near-side peak and long-range correlations is applied to the data and the peak shape is quantified by the variance of the distributions. While the width of the peak in the Delta phi direction is almost independent of centrality, a significant broadening in the Delta eta direction is found from peripheral to central collisions. This feature is prominent for the low-p(T) region and vanishes above 4 GeV/c. The widths measured in peripheral collisions are equal to those in pp collisions in the Delta phi direction and above 3 GeV/c in the Delta eta direction. Furthermore, for the 10% most central collisions and 1 <p(T, assoc) <2 GeV/c, 1 <p(T,trig) <3 GeV/c, a departure from a Gaussian shape is found: a depletion develops around the center of the peak. The results are compared to A Multi-Phase Transport (AMPT) model simulation as well as other theoretical calculations indicating that the broadening and the development of the depletion are connected to the strength of radial and longitudinal flow.
  • Adam, J.; Brucken, E. J.; Chang, B.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; Viinikainen, J.; The ALICE collaboration (2017)
    We present the first measurement of the two-particle transverse momentum differential correlation function, P-2 = / <p(T)>(2), in Pb-Pb collisions at root s(NN) = 2.76 TeV. Results for P-2 are reported as a function of the relative pseudorapidity (Delta eta) and azimuthal angle (Delta phi) between two particles for different collision centralities. The Delta phi dependence is found to be largely independent of Delta eta for broken vertical bar Delta eta broken vertical bar >= 0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around Delta phi=pi (i. e., on the away side), which is not observed in number correlations in the same centrality range, and thus provides an indication of the dominance of triangular flow in this collision centrality. Fourier decompositions of P-2, studied as a function of the collision centrality, show that correlations at broken vertical bar Delta eta broken vertical bar >= 0.9 can be well reproduced by a flow ansatz based on the notion that measured transverse momentum correlations are strictly determined by the collective motion of the system.
  • Acharya, S.; Brucken, E. J.; Chang, B.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; Viinikainen, J.; The ALICE collaboration (2017)
    We present the results of three-dimensional femtoscopic analyses for charged and neutral kaons recorded by ALICE in Pb-Pb collisions at root s(NN) = 2.76 TeV. Femtoscopy is used to measure the space-time characteristics of particle production from the effects of quantum statistics and final-state interactions in two-particle correlations. Kaon femtoscopy is an important supplement to that of pions because it allows one to distinguish between different model scenarios working equally well for pions. In particular, we compare the measured three-dimensional kaon radii with a purely hydrodynamical calculation and a model where the hydrodynamic phase is followed by a hadronic rescattering stage. The former predicts an approximate transverse mass (m(T)) scaling of source radii obtained from pion and kaon correlations. This m(T) scaling appears to be broken in our data, which indicates the importance of the hadronic rescattering phase at LHC energies. A k(T) scaling of pion and kaon source radii is observed instead. The time of maximal emission of the system is estimated by using the three-dimensional femtoscopic analysis for kaons. The measured emission time is larger than that of pions. Our observation is well supported by the hydrokinetic model predictions.
  • Suutari, Pasi (Helsingin yliopisto, 2020)
    Pro gradu- tutkielmassani käsittelen Espanjan kahden enemmistöpuoleen: Espanjan työväen puolueen (esp. Partido Socialista Obrero español lyh. PSOE) sekä Espanjan kansan puolueen (esp. Partido Popular lyh. PP) maahanmuuttopolitiikkaan liittyvän julkisuuskuvan rakentumista. Maahanmuutto ei ole vain sosiaalinen ilmiö, vaan polisoitunutkin ilmiö, joka aktivoituu maailmassa vallitsevan poliittisen ja taloudellisen tilanteen mukaan. Tutkielmassani pyrin selvittämään, millaisen julkisuuskuvan sekä PSOE- puolue että PP-puolue antavat ja miten ne rakentavat sitä kielen keinoin käsitellessään maahanmuuttoa. Tutkimuksessani hyödynnän kahta teoreettista viitekehystä. Näkemys kielenkäytöstä pohjautuu kriittiseen diskurssianalyysiin (CDA). Näkemys kielestä seuraa M.A.K. Hallidayn kehittelemää systeemis-funktionaalista kielioppia (SFL). Tutkimusmateriaalin analysoimiseen seká ilmausten merkitysten avamiseen lukijalle käytän lingvistisinä työvälineinä myös mm. modaalisuus,- nominaalisuus,- nimeämis-ja persoonattomuuskäsitteitä sekä rekisterianalyysia, joka on osa systeemis-funktionaalista kielioppia. Systeemis-funktionaalisen kieliopin mukaan kielessä on kolme pääfunktiota: ideationaalinen funktio, interpersoonainen funktio ja tekstuaalinen funktio. Tutkimuksessa käytän kahta ensimmäistä funktiota. Tutkin ideationaalista funktiota analysoimalla mm. sanaston, verbien prosessityyppien, nominaalisuus- ja persoonattomuukäsitteiden avulla PSOE- puolueen sekä PP- puolueen rooleja ja toimintaa. Interpersoonaista funktiota tarkastelen vallan ja sitoutuneisuuden näkökulmasta.Vallan ja sitoutuneisuuden tutkimiseen käytän mm. modaalisuus,- nimeämis- ja nominaalisuuskäsitteitä. Aineistoni koostuu sekä PSOE- puolueen että PP- puolueen kevään 2019 parlamenttivaaliohjelmista, joissa ne esittelevät oman maahanmuuttopoliikkansa ja poliittikkavaihtoehtonsa lukijalle. Puolueiden julkisuuskuvat muodostuvat melko samanlaisten kielellisten keinojen seurauksena sekä suhteet muihin rakentuvat melko etäisiksi huolimatta siitä,että puolueet yrittävät rakentaa läheisempää kuvaa itsestänsä. PSOE- puolue rakentaa julkisuuskuvaa hallituspuolueena, vaaliehdokkaana ja asiantuntijana, kun PP-puolue esiintyy vaaliehdokkaana ja poliittisen pääävastustajansa kritisoijana. Molempien puoluieden puheenaiheiden painotukset heijastelevat niiden poliittisia rooleja. Ne takaavat sekä Espanjan kansalaisten turvallisuuden että maahanmuuttajien turvallisuuden ja poliittisten oikeuksien toteutumisen. Vaaliohjelmat eivät kuitenkaan toimi aidon vuorovaikutuksen välineenä.Vaaliohjelmissaan puolueet rakentavat todellisuutta, jossa niillä on aktiivinen rooli ja ääoikeutetuilla, muilla kansalaisilla sekä maahanmuuttajilla on passiivinen rooli. Vaaliohjelmissa äänestäjät, muut kansalaiset ja maahanmuuttajat pikemminkin näyttäyvät massoina vailla mahdollisuuksia kommentoida vaaliohjelmia ja vaikuttaa tilanteeseensa.
  • The ALICE collaboration; Acharya, S.; Brücken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Parkkila, J. E.; Rak, J.; Räsänen, S. S.; Saarinen, S.; Slupecki, M.; Snellman, T. W.; Trzaska, W. H.; Vargyas, M.; Viinikainen, J. (2019)
    The first measurement of dielectron (e(+)e(-)) production in central (0-10%) Pb-Pb collisions at root S-NN = 2.76 TeV at the LHC is presented. The dielectron invariant-mass spectrum is compared to the expected contributions from hadron decays in the invariant-mass range 0 < m(ee) < 3.5 GeV/c(2). The ratio of data and the cocktail of hadronic contributions without vacuum rho(0) is measured in the invariant-mass range 0.15 < m(ee) < 0.7 GeV/c(2), where an excess of dielectrons is observed in other experiments, and its value is 1.40 +/- 0.28 (stat.) +/- 0.08 (syst.) +/- 0.27 (cocktail). The dielectron spectrum measured in the invariant mass range 0 < m(ee) < 1 GeV/c(2) is consistent with the predictions from two theoretical model calculations that include thermal dielectron production from both partonic and hadronic phases with in-medium broadened rho(0) meson. The fraction of direct virtual photons over inclusive virtual photons is extracted for dielectron pairs with invariant mass 0.1 < m(ee) < 0.3 GeV/c(2) and in the transverse-momentum intervals 1 <( )p(T,ee) < 2 GeV/c and 2 < p(T,ee) < 4 GeV/c. The measured fraction of virtual direct photons is consistent with the measurement of real direct photons by ALICE and with the expectations from previous dielectron measurements at RHIC within the experimental uncertainties.
  • The CMS collaboration; Sirunyan, A. M.; Eerola, P.; Kirschenmann, H.; Pekkanen, J.; Voutilainen, M.; Havukainen, J.; Heikkilä, J. K.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Laurila, S.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Siikonen, H.; Tuominen, E.; Tuominiemi, J.; Tuuva, T. (2019)
    This Letter reports measurements of differential cross sections for the production of two Z bosons in association with jets in proton-proton collisions at root s = 8 and 13 TeV. The analysis is based on data samples collected at the LHC with the CMS detector, corresponding to integrated luminosities of 19.7 and 35.9 fb(-1) at 8 and 13 TeV, respectively. The measurements are performed in the leptonic decay modes ZZ -> l(+)l(-)l'(+)l'(-), where, l, l' = e, mu The differential cross sections as a function of the jet multiplicity, the transverse momentum p(T), and pseudorapidity of the P-T-leading and subleading jets are presented. In addition, the differential cross sections as a function of variables sensitive to the vector boson scattering, such as the invariant mass of the two P-T-leading jets and their pseudorapidity separation, are reported. The results are compared to theoretical predictions and found in good agreement within the theoretical and experimental uncertainties. (C) 2018 The Author(s). Published by Elsevier B.V.
  • Acharya, S.; Brucken, E. J.; Chang, B.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; Viinikainen, J.; The ALICE collaboration (2017)
    We present the first ever measurements of femtoscopic correlations between the K-S(0) and K-+/- particles. The analysis was performed on the data from Pb-Pb collisions at root S-NN = 2.76 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding via the a(0)(980) resonance. The extracted kaon source radius and correlation strength parameters for (KSK-)-K-0 are found to be equal within the experimental uncertainties to those for (KSK+)-K-0. Comparing the results of the present study with those from published identical-kaon femtoscopic studies by ALICE, mass and coupling parameters for the a(0) resonance are tested. Our results are also compatible with the interpretation of the a(0) having a tetraquark structure instead of that of a diquark. (c) 2017 The Author. Published by Elsevier B.V.
  • Adam, J.; Brucken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Kral, J.; Mieskolainen, M. M.; Rak, J.; Rasanen, S. S.; Snellman, T. W.; Trzaska, W. H.; The ALICE collaboration (2015)
    The size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of pi(+/-) pi(+/-), K-+/- K-+/-, K-S(0) K-S(0), pp, and (pp) over bar correlations from Pb-Pb collisions at root s(NN) = 2.76 TeV by the ALICE experiment at the LHC. One-dimensional radii of the system are extracted from correlation functions in terms of the invariant momentum difference of the pair. The comparison of the measured radii with the predictions from a hydrokinetic model is discussed. The pion and kaon source radii display a monotonic decrease with increasing average pair transverse mass m(T) which is consistent with hydrodynamic model predictions for central collisions. The kaon and proton source sizes can be reasonably described by approximate m(T) scaling.
  • The ALICE collaboration; Acharya, S.; Brucken, E. J.; Chang, B.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Saarinen, S.; Slupecki, M.; Snellman, T. W.; Trzaska, W. H.; Vargyas, M.; Viinikainen, J. (2018)
    An invariant differential cross section measurement of inclusive pi(0) and eta meson production atmid-rapidity in pp collisions at root s = 8 TeV was carried out by the ALICE experiment at the LHC. The spectra of pi(0) and eta mesons were measured in transverse momentum ranges of 0.3 <p(T) <35 GeV/c and 0.5 <p(T) <35 GeV/c, respectively. Next-to-leading order perturbative QCD calculations using fragmentation functions DSS14 for the pi(0) and AESSS for the. overestimate the cross sections of both neutral mesons, although such calculations agree with the measured eta/pi(0) ratio within uncertainties. The results were also compared with PYTHIA 8.2 predictions for which the Monash 2013 tune yields the best agreement with the measured neutral meson spectra. The measurements confirm a universal behavior of the eta/pi(0) ratio seen forNA27, PHENIX and ALICE data for pp collisions from root s = 27.5 GeV to root s = 8 TeV within experimental uncertainties. A relation between the pi(0) and eta production cross sections for pp collisions at root s = 8 TeV is given by m(T) scaling for p(T) > 3.5 GeV/c. However, a deviation from this empirical scaling rule is observed for transverse momenta below p(T) <3.5 GeV/c in the eta/pi(0) ratio with a significance of 6.2 sigma.
  • Adam, J.; Brucken, E. J.; Chang, B.; Kim, D. J.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; The ALICE collaboration (2016)
    The pseudorapidity (eta) and transverse-momentum (p(T)) distributions of charged particles produced in proton-proton collisions are measured at the centre-of-mass energy root s = 13 TeV. The pseudorapidity distribution in vertical bar eta vertical bar <1.8 is reported for inelastic events and for events with at least one charged particle in vertical bar eta vertical bar <1. The pseudorapidity density of charged particles produced in the pseudorapidity region vertical bar eta vertical bar <0.5 is 5.31 +/- 0.18 and 6.46 +/- 0.19 for the two event classes, respectively. The transverse-momentum distribution of charged particles is measured in the range 0.15 <p(T) <20 GeV/c and vertical bar eta vertical bar <0.8 for events with at least one charged particle in vertical bar eta vertical bar <1. The evolution of the transverse momentum spectra of charged particles is also investigated as a function of event multiplicity. The results are compared with calculations from PYTHIA and EPOS Monte Carlo generators. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
  • The CMS collaboration; Sirunyan, A. M.; Eerola, P.; Kirschenmann, H.; Pekkanen, J.; Voutilainen, M.; Havukainen, J.; Heikkilä, J. K.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Laurila, S.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Siikonen, H.; Tuominen, E.; Tuominiemi, J.; Tuuva, T. (2018)
    Searches for resonances decaying into pairs of jets are performed using proton-proton collision data collected at root s = 13 TeV corresponding to an integrated luminosity of up to 36 fb(-1). A low-mass search, for resonances with masses between 0.6 and 1.6 TeV, is performed based on events with dijets reconstructed at the trigger level from calorimeter information. A high-mass search, for resonances with masses above 1.6 TeV, is performed using dijets reconstructed offline with a particle-flow algorithm. The dijet mass spectrum is well described by a smooth parameterization and no evidence for the production of new particles is observed. Upper limits at 95% confidence level are reported on the production cross section for narrow resonances with masses above 0.6 TeV. In the context of specific models, the limits exclude string resonances with masses below 7.7 TeV, scalar diquarks below 7.2 TeV, axigluons and colorons below 6.1 TeV, excited quarks below 6.0 TeV, color-octet scalars below 3.4 TeV, W' bosons below 3.3 TeV, Z' bosons below 2.7 TeV, Randall-Sundrum gravitons below 1.8 TeV and in the range 1.9 to 2.5 TeV, and dark matter mediators below 2.6 TeV. The limits on both vector and axial-vector mediators, in a simplified model of interactions between quarks and dark matter particles, are presented as functions of dark matter particle mass and coupling to quarks. Searches are also presented for broad resonances, including for the first time spin-1 resonances with intrinsic widths as large as 30% of the resonance mass. The broad resonance search improves and extends the exclusions of a dark matter mediator to larger values of its mass and coupling to quarks.