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A search for pair production of new light bosons decaying into muons in proton-proton collisions at 13 ?TeV

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
A search for new light bosons decaying into muon pairs is presented using a data sample corresponding to an integrated luminosity of 35.9 fb−1 of proton-proton collisions at a center-of-mass energy √s =13 TeV, collected with the CMS detector at the CERN LHC. The search is model independent, only requiring the pair production of a new light boson and its subsequent decay to a pair of muons. No significant deviation from the predicted background is observed. A model independent limit is set on the product of the production cross section times branching fraction to dimuons squared times acceptance as a function of new light boson mass. This limit varies between 0.15 and 0.39 fb over a range of new light boson masses from 0.25 to 8.5 GeV. It is then interpreted in the context of the next-to-minimal supersymmetric standard model and a dark supersymmetry model that allows for nonnegligible light boson lifetimes. In both cases, there is significant improvement over previously published limits.
Proyecto:


Azimuthal separation in nearly back-to-back jet topologies in inclusive 2- and 3-jet events in pp collisions at √s = 13 TeV

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, Δφ12, is presented. The measurement considers events where the two leading jets are nearly collinear (“back-to-back”) in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 35.9 fb−1 are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region 177º < Δφ12 < 180º. The 2- and 3-jet measurements are not simultaneously described by any of models.
Proyecto:


Centrality and pseudorapidity dependence of the transverse energy density in pPb collisions at √sNN = 5.02 TeV

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
The almost hermetic coverage of the CMS detector is used to measure the distribution of transverse energy,ET, over 13.2 units of pseudorapidity, η, for pPb collisions at a center-of-mass energy per nucleon pair of √sNN =5.02 TeV. The huge angular acceptance exploits the fact that the CASTOR calorimeter at −6.6 <η< −5.2 is effectively present on both sides of the colliding system because of a switch in the proton-going and lead-going beam directions. This wide acceptance enables the study of correlations between well-separated angular regions and makes the measurement a particularly powerful test of event generators. For minimum bias pPb collisions the maximum value of dET/dη is 22 GeV, which implies an ET per participant nucleon pair comparable to that of peripheral PbPb collisions at √sNN = 2.76 TeV. The increase of dET/dη with centrality is much stronger for the lead-going side than for the proton-going side. The η dependence of dET/dη is sensitive to the η range in which the centrality variable is defined. Several modern generators are compared to these results but none is able to capture all aspects of the η and centrality dependence of the data and the correlations observed between different η regions.
Proyecto:


Charged-particle angular correlations in XeXe collisions at √sNN = 5.44 TeV

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
Azimuthal correlations of charged particles in xenon-xenon collisions at a center-of-mass energy per nucleon pair of √sNN = 5.44 TeV are studied. The data were collected by the CMS experiment at the LHC with a total integrated luminosity of 3.42 μb−1. The collective motion of the system formed in the collision is parametrized by a Fourier expansion of the azimuthal particle density distribution. The azimuthal anisotropy coefficients v2, v3, and v4 are obtained by the scalar-product, two-particle correlation, and multiparticle correlation methods. Within a hydrodynamic picture, these methods have different sensitivities to noncollective and fluctuation effects. The dependence of the Fourier coefficients on the size of the colliding system is explored by comparing the xenonxenon results with equivalent lead-lead data. Model calculations that include initial-state fluctuation effects are also compared to the experimental results. The observed angular correlations provide new constraints on the hydrodynamic description of heavy ion collisions.
Proyecto:


Combination of CMS searches for heavy resonances decaying to pairs of bosons or leptons

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • Gómez Gramuglio, Gervasio
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vizán García, Jesús Manuel
A statistical combination of searches for heavy resonances decaying to pairs of bosons or leptons is presented. The data correspond to an integrated luminosity of 35.9 fb−1 collected during 2016 by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data are found to be consistent with expectations from the standard model background. Exclusion limits are set in the context of models of spin-1 heavy vector triplets and of spin-2 bulk gravitons. For massdegenerate W´ and Z´ resonances that predominantly couple to the standard model gauge bosons, the mass exclusion at 95% confidence level of heavy vector bosons is extended to 4.5 TeV as compared to 3.8 TeV determined from the best individual channel. This excluded mass increases to 5.0 TeV if the resonances couple predominantly to fermions.
Proyecto:


Combination of Searches for Higgs Boson Pair Production in Proton-Proton Collisions at √s=13 TeV

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
This Letter describes a search for Higgs boson pair production using the combined results from four final states: bbγγ, bbττ, bbbb, and bbVV, where V represents a W or Z boson. The search is performed using data collected in 2016 by the CMS experiment from LHC proton-proton collisions at √s =13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. Limits are set on the Higgs boson pair production cross section. A 95% confidence level observed (expected) upper limit on the nonresonant production cross section is set at 22.2 (12.8) times the standard model value. A search for narrow resonances decaying to Higgs boson pairs is also performed in the mass range 250–3000 GeV. No evidence for a signal is observed, and upper limits are set on the resonance production cross section.
Proyecto:


Combined measurements of Higgs boson couplings in proton–proton collisions at √s =13 TeV

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
CCombined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton–proton collision data set recorded with the CMS detector in 2016 at √s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quarkantiquark pair) and the following decay modes: H → γ γ , ZZ, WW, ꚍ ꚍ , bb, and μμ. Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be μ = 1.17 ± 0.10, assuming a Higgs boson mass of 125.09 GeV. Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.
Proyecto:


Combinations of single-top-quark production cross-section measurements and |fLVVtb| determinations at √s = 7 and 8 TeV with the ATLAS and CMS experiments

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
This paper presents the combinations of single-top-quark production cross-section measurements by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at √s = 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb−1 at √s = 7 TeV and 12.2 to 20.3 fb−1 at √s = 8 TeV. These combinations are performed per centre-of-mass energy and for each production mode: t-channel, tW, and s-channel. The combined t-channel cross-sections are 67.5 ± 5.7 pb and 87.7 ± 5.8 pb at √s = 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 ± 4.1 pb and 23.1 ± 3.6 pb at √s = 7 and 8 TeV respectively. For the s-channel cross-section, the combination yields 4.9 ± 1.4 pb at √s = 8 TeV. The square of the magnitude of the CKM matrix element Vtb multiplied by a form factor fLV is determined for each production mode and centre-of-mass energy, using the ratio of the measured cross-section to its theoretical prediction. It is assumed that the top-quark-related CKM matrix elements obey the relation |Vtd|, |Vts| ≪ |Vtb|. All the |fLVVtb|2 determinations, extracted from individual ratios at √s = 7 and 8 TeV, are combined, resulting in |fLVVtb| = 1.02 ± 0.04 (meas.) ± 0.02 (theo.). All combined measurements are consistent with their corresponding Standard Model predictions.
Proyecto:


An embedding technique to determine ꚍꚍ backgrounds in proton-proton collision data

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
An embedding technique is presented to estimate standard model ττ backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed μμ events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at √s=13 TeV corresponding to an integrated luminosity of 41.5 fb−1.
Proyecto:


Constraints on anomalous HVV couplings from the production of Higgs bosons decaying to τ lepton pairs

  • Sirunyan, A. M.
  • Cabrillo Bartolomé, José Iban
  • Calderón Tazón, Alicia
  • Chazin Quero, Bárbara
  • Duarte Campderros, Jorge
  • Fernández García, Marcos
  • Fernández Manteca, Pedro José
  • García Alonso, Andrea
  • García Ferrero, Juan
  • Gómez Gramuglio, Gervasio
  • López Virto, María Amparo
  • Marco de Lucas, Jesús
  • Martínez Rivero, Celso
  • Martínez Ruiz de Árbol, Pablo
  • Matorras Weinig, Francisco
  • Piedra Gómez, Jonatan
  • Prieels, Cedric Gerald
  • Rodrigo Anoro, Teresa
  • Ruiz Jimeno, Alberto
  • Scodellaro, Luca
  • Trevisani, Nicolo
  • Vila Álvarez, Ivan
  • Vilar Cortabitarte, Rocío
A study is presented of anomalous HVV interactions of the Higgs boson, including its CP properties. The study uses Higgs boson candidates produced mainly in vector boson fusion and gluon fusion that subsequently decay to a pair of τ leptons. The data were recorded by the CMS experiment at the LHC in 2016 at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 35.9  fb−1 . A matrix element technique is employed for the analysis of anomalous interactions. The results are combined with those from the H→4ℓ decay channel presented earlier, yielding the most stringent constraints on anomalous Higgs boson couplings to electroweak vector bosons expressed as effective cross section fractions and phases: the CP -violating parameter fa3cos(ϕa3)=(0.00±0.27)×10−3 and the CP -conserving parameters fa2cos(ϕa2)=(0.08+1.04−0.21)×10−3 , fΛ1cos(ϕΛ1)=(0.00+0.53−0.09)×10−3 , and fZγΛ1cos(ϕZγΛ1)=(0.0+1.1−1.3)×10−3 . The current dataset does not allow for precise constraints on CP properties in the gluon fusion process. The results are consistent with standard model expectations.
Proyecto:


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