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N. De Filippis

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Papers by N. De Filippis

Inclusive Search for a Highly Boosted Higgs Boson Decaying to a Bottom Quark-Antiquark Pair

Physical Review Letters, 2018

An inclusive search for the standard model Higgs boson (H) produced with large transverse momentu... more An inclusive search for the standard model Higgs boson (H) produced with large transverse momentum (p_{T}) and decaying to a bottom quark-antiquark pair (bb[over ¯]) is performed using a data set of pp collisions at sqrt[s]=13 TeV collected with the CMS experiment at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb^{-1}. A highly Lorentz-boosted Higgs boson decaying to bb[over ¯] is reconstructed as a single, large radius jet, and it is identified using jet substructure and dedicated b tagging techniques. The method is validated with Z→bb[over ¯] decays. The Z→bb[over ¯] process is observed for the first time in the single-jet topology with a local significance of 5.1 standard deviations (5.8 expected). For a Higgs boson mass of 125 GeV, an excess of events above the expected background is observed (expected) with a local significance of 1.5 (0.7) standard deviations. The measured cross section times branching fraction for production via gluon fusion of H→...

$Research paper thumbnail of Search for direct production of GeV-scale resonances decaying to a pair of muons in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV$

Search for direct production of GeV-scale resonances decaying to a pair of muons in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

Journal of High Energy Physics, 2023

A bstract A search for direct production of low-mass dimuon resonances is performed using $$ \sqr... more A bstract A search for direct production of low-mass dimuon resonances is performed using $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV proton-proton collision data collected by the CMS experiment during the 2017–2018 operation of the CERN LHC with an integrated luminosity of 96 . 6 fb − 1 . The search exploits a dedicated high-rate trigger stream that records events with two muons with transverse momenta as low as 3 GeV but does not include the full event information. The search is performed by looking for narrow peaks in the dimuon mass spectrum in the ranges of 1.1–2.6 GeV and 4.2–7.9 GeV. No significant excess of events above the expectation from the standard model background is observed. Model-independent limits on production rates of dimuon resonances within the experimental fiducial acceptance are set. Competitive or world’s best limits are set at 90% confidence level for a minimal dar...

$Research paper thumbnail of Searches for additional Higgs bosons and for vector leptoquarks in ττ final states in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV$

Searches for additional Higgs bosons and for vector leptoquarks in ττ final states in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

Journal of High Energy Physics, 2023

A bstract Three searches are presented for signatures of physics beyond the standard model (SM) i... more A bstract Three searches are presented for signatures of physics beyond the standard model (SM) in ττ final states in proton-proton collisions at the LHC, using a data sample collected with the CMS detector at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV, corresponding to an integrated luminosity of 138 fb − 1 . Upper limits at 95% confidence level (CL) are set on the products of the branching fraction for the decay into τ leptons and the cross sections for the production of a new boson ϕ , in addition to the H(125) boson, via gluon fusion (gg ϕ ) or in association with b quarks, ranging from $$ \mathcal{O} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>O</mml:mi> </mml:math> (10 pb) for a mass of 60 GeV to 0.3 fb for a mass of 3.5 TeV each. The data reveal two excesses for gg ϕ production with local p -values equivalent to about three standard deviations at m ϕ = 0 . 1...

$Research paper thumbnail of Search for heavy Majorana neutrinos in same-sign dilepton channels in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV$

Search for heavy Majorana neutrinos in same-sign dilepton channels in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

Journal of High Energy Physics, 2018

A bstract A search is performed for a heavy Majorana neutrino (N), produced in leptonic decay of ... more A bstract A search is performed for a heavy Majorana neutrino (N), produced in leptonic decay of a W boson propagator and decaying into a W boson and a lepton, with the CMS detector at the LHC. The signature used in this search consists of two same-sign leptons, in any flavor combination of electrons and muons, and at least one jet. The data were collected during 2016 in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb −1 . The results are found to be consistent with the expected standard model background. Upper limits are set in the mass range between 20 and 1600 GeV in the context of a Type-I seesaw mechanism, on | V eN | 2 , | V μ N | 2 , and | V eN V μN * | 2 /(| V eN | 2 + | V μ N | 2 ), where V ℓN is the matrix element describing the mixing of N with the standard model neutrino of flavor ℓ = e , μ . For N masses between 20 and 1600 GeV, the upper limits on | V ℓN | 2 range between 2 . 3 × 10 −5 and unity. These...

Search for lepton-flavor violating decays of the Higgs boson in the μτ and eτ final states in proton-proton collisions at s<…

Physical review, 2021

A search is presented for lepton-flavor violating decays of the Higgs boson to $\mu\tau$ and e$\t... more A search is presented for lepton-flavor violating decays of the Higgs boson to $\mu\tau$ and e$\tau$. The data set corresponds to an integrated luminosity of 137 fb$^{-1}$ collected at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. No significant excess has been found, and the results are interpreted in terms of upper limits on lepton-flavor violating branching fractions of the Higgs boson. The observed (expected) upper limits on the branching fractions are, respectively, $\mathcal{B}($H $\to\mu\tau)$ $\lt$ 0.15 (0.15)% and $\mathcal{B}($H$\to$e$\tau)$ $\lt$ 0.22 (0.16)% at 95% confidence level.

$Research paper thumbnail of Search for resonant and nonresonant Higgs boson pair production in the b b ¯ ℓνℓν $$ \mathrm{b}\overline{\mathrm{b}}\mathit{\ell \nu \ell \nu } $$ final state in proton-proton collisions at s = 13 $$ \sqrt{s}=13 $$ TeV$

Search for resonant and nonresonant Higgs boson pair production in the b b ¯ ℓνℓν $$ \mathrm{b}\overline{\mathrm{b}}\mathit{\ell \nu \ell \nu } $$ final state in proton-proton collisions at s = 13 $$ \sqrt{s}=13 $$ TeV

Journal of High Energy Physics, 2017

Searches for resonant and nonresonant pair-produced Higgs bosons (HH) decaying respectively into ... more Searches for resonant and nonresonant pair-produced Higgs bosons (HH) decaying respectively into ll nu nu, through either W or Z bosons, and bbbar are presented. The analyses are based on a sample of proton-proton collisions at sqrt(s) = 13 TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 inverse femtobarns. Data and predictions from the standard model are in agreement within uncertainties. For the standard model HH hypothesis, the data exclude at 95% confidence level a product of the production cross section and branching fraction larger than 72 fb, corresponding to 79 times the prediction, consistent with expectations. Constraints are placed on different scenarios considering anomalous couplings, which could affect the rate and kinematics of HH production. Upper limits at 95% confidence level are set on the production cross section of narrow-width spin-0 and spin-2 particles decaying to Higgs boson pairs, the latter produced with m...

Search for a massive resonance decaying to a pair of Higgs bosons in the four b quark final state in proton–proton collisions at s=13TeV

Physics Letters B, 2018

A search for a massive resonance decaying into a pair of standard model Higgs bosons, in a final ... more A search for a massive resonance decaying into a pair of standard model Higgs bosons, in a final state consisting of two b quark–antiquark pairs, is performed. A data sample of proton–proton collisions at a centre-of-mass energy of 13 TeV is used, collected by the CMS experiment at the CERN LHC in 2016, and corresponding to an integrated luminosity of 35.9fb−1. The Higgs bosons are highly Lorentz-boosted and are each reconstructed as a single large-area jet. The signal is characterized by a peak in the dijet invariant mass distribution, above a background from the standard model multijet production. The observations are consistent with the background expectations, and are interpreted as upper limits on the products of the s-channel production cross sections and branching fractions of narrow bulk gravitons and radions in warped extra-dimensional models. The limits range from 126 to 1.4 fb at 95% confidence level for resonances with masses between 750 and 3000 GeV, and are the most st...

Search for pair production of vector-like quarks in the bWb‾W channel from proton–proton collisions at

Physics Letters B, 2018

A search is presented for the production of vector-like quark pairs, or , with electric charge of... more A search is presented for the production of vector-like quark pairs, or , with electric charge of 2/3 (T) or (Y), in proton–proton collisions at . The data were collected by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of . The T and Y quarks are assumed to decay exclusively to a W boson and a b quark. The search is based on events with a single isolated electron or muon, large missing transverse momentum, and at least four jets with large transverse momenta. In the search, a kinematic reconstruction of the final state observables is performed, which would permit a signal to be detected as a narrow mass peak (≈7% resolution). The observed number of events is consistent with the standard model prediction. Assuming strong pair production of the vector-like quarks and a 100% branching fraction to , a lower limit of 1295 GeV at 95% confidence level is set on the T and Y quark masses.

Search for the Higgs Boson Decaying to Two Muons in Proton-Proton Collisions at s=13 TeV

Physical Review Letters, 2019

A search for the Higgs boson decaying to two oppositely charged muons is presented using data rec... more A search for the Higgs boson decaying to two oppositely charged muons is presented using data recorded by the CMS experiment at the CERN LHC in 2016 at a center-of-mass energy sqrt[s]=13 TeV, corresponding to an integrated luminosity of 35.9 fb^{-1}. Data are found to be compatible with the predicted background. For a Higgs boson with a mass of 125.09 GeV, the 95% confidence level observed (background-only expected) upper limit on the production cross section times the branching fraction to a pair of muons is found to be 3.0 (2.5) times the standard model expectation. In combination with data recorded at center-of-mass energies sqrt[s]=7 and 8 TeV, the background-only expected upper limit improves to 2.2 times the standard model value with a standard model expected significance of 1.0 standard deviation. The corresponding observed upper limit is 2.9 with an observed significance of 0.9 standard deviation. This corresponds to an observed upper limit on the standard model Higgs boson ...

$Research paper thumbnail of Search for disappearing tracks as a signature of new long-lived particles in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV$

Search for disappearing tracks as a signature of new long-lived particles in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

Journal of High Energy Physics, 2018

A bstract A search is presented for long-lived charged particles that decay within the CMS detect... more A bstract A search is presented for long-lived charged particles that decay within the CMS detector and produce the signature of a disappearing track. A disappearing track is an isolated track with missing hits in the outer layers of the silicon tracker, little or no energy in associated calorimeter deposits, and no associated hits in the muon detectors. This search uses data collected with the CMS detector in 2015 and 2016 from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to an integrated luminosity of 38.4 fb −1 . The results of the search are interpreted in the context of the anomaly-mediated supersymmetry breaking model. The data are consistent with the background-only hypothesis. Limits are set on the product of the cross section for direct production of charginos and their branching fraction to a neutralino and a pion, as a function of the chargino mass and lifetime. At 95% confidence level, charginos with masses below 715 (695) GeV a...

$Research paper thumbnail of Measurement of the cross section for top quark pair production in association with a W or Z boson in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV$

Measurement of the cross section for top quark pair production in association with a W or Z boson in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

Journal of High Energy Physics, 2018

A bstract A measurement is performed of the cross section of top quark pair production in associa... more A bstract A measurement is performed of the cross section of top quark pair production in association with a W or Z boson using proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb −1 , collected by the CMS experiment in 2016. The measurement is performed in the same-sign dilepton, three- and four-lepton final states. The production cross sections are measured to be $$ \sigma \left(\mathrm{t}\overline{\mathrm{t}}\mathrm{W}\right)={0.77}_{-0.11}^{+0.12}{\left(\mathrm{stat}\right)}_{-0.12}^{+0.13}\left(\mathrm{syst}\right)\mathrm{p}\mathrm{b} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>σ</mml:mi> <mml:mfenced> <mml:mrow> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>W</mml:mi> </mml:mrow> </mml:mfenced> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mn>0.77</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.11</mml:mn> </mml:mrow> <mml:mrow>...

Search for Leptoquarks Coupled to Third-Generation Quarks in Proton-Proton Collisions at s=13 TeV

Physical Review Letters, 2018

Three of the most significant measured deviations from standard model predictions, the enhanced d... more Three of the most significant measured deviations from standard model predictions, the enhanced decay rate for B $\to$ D$^{(*)}\tau\nu$, hints of lepton universality violation in B $\to$ K$^{(*)}\ell\ell$ decays, and the anomalous magnetic moment of the muon, can be explained by the existence of leptoquarks (LQs) with large couplings to third-generation quarks and masses at the TeV scale. The existence of these states can be probed at the LHC in high energy proton-proton collisions. A novel search is presented for pair production of LQs coupled to a top quark and a muon using data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$, recorded by the CMS experiment. No deviation from the standard model prediction has been observed and scalar LQs decaying exclusively into t$\mu$ are excluded up to masses of 1420 GeV. The results of this search are combined with those from previous searches for LQ decays into t$\tau$ and b$\nu$, which exclud...

Measurement of the properties of a Higgs boson in the four-lepton final state

Physical review, 2014

The properties of a Higgs boson candidate are measured in the H to ZZ to 4l decay channel, with l... more The properties of a Higgs boson candidate are measured in the H to ZZ to 4l decay channel, with l = e, mu, using data from pp collisions corresponding to an integrated luminosity of 5.1 inverse femtobarns at the center-of-mass energy of sqrt(s) = 7 TeV and 19.7 inverse femtobarns at sqrt(s) = 8 TeV, recorded with the CMS detector at the LHC. The new boson is observed as a narrow resonance with a local significance of 6.8 standard deviations, a measured mass of 125.6 +- 0.4 (stat) +- 0.2 (syst) GeV, and a total width less than 3.4 GeV at the 95% confidence level. The production cross section of the new boson times its branching fraction to four leptons is measured to be 0.93 +0.26 -0.23 (stat) +0.13 -0.09 (syst) times that predicted by the standard model. Its spin-parity properties are found to be consistent with the expectations for the standard model Higgs boson. The hypotheses of a pseudoscalar and all tested spin-one boson hypotheses are excluded at the 99% confidence level or hi...

Combined Measurement of the Higgs Boson Mass inppCollisions ats=7and 8 TeV with the ATLAS and CMS Experiments

Physical Review Letters, 2015

A measurement of the Higgs boson mass is presented based on the combined data samples of the ATLA... more A measurement of the Higgs boson mass is presented based on the combined data samples of the ATLAS and CMS experiments at the CERN LHC in the $H \rightarrow \gamma\gamma$ and $H \rightarrow ZZ\rightarrow 4\ell$ decay channels. The results are obtained from a simultaneous fit to the reconstructed invariant mass peaks in the two channels and for the two experiments. The measured masses from the individual channels and the two experiments are found to be consistent among themselves. The combined measured mass of the Higgs boson is $m_{H} = 125.09\pm0.21\,\mathrm{(stat.)}\pm0.11\,\mathrm{(syst.)}~\mathrm{GeV}$.

Performance of the local reconstruction algorithms for the CMS hadron calorimeter with Run 2 data

Journal of Instrumentation, Oct 31, 2023

A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadr... more A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadron calorimeter during Run 2 (2015–2018) of the LHC. During Run 2, the characteristic bunch-crossing spacing for proton-proton collisions was 25 ns, which resulted in overlapping signals from adjacent crossings. The energy corresponding to a particular bunch crossing of interest is estimated using the known pulse shapes of energy depositions in the calorimeter, which are measured as functions of both energy and time. A variety of algorithms were developed to mitigate the effects of adjacent bunch crossings on local energy reconstruction in the hadron calorimeter in Run 2, and their performance is compared.

$Research paper thumbnail of Observation of new structure in the J/$\psi$J/$\psi$ mass spectrum in proton-proton collisions at $\sqrt{s}$ = 13 TeV$

Observation of new structure in the J/$\psi$J/$\psi$ mass spectrum in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search is reported for near-threshold structures in the J/ψJ/ψ invariant mass spectrum produced... more A search is reported for near-threshold structures in the J/ψJ/ψ invariant mass spectrum produced in proton-proton collisions at √ s = 13 TeV from data collected by the CMS experiment, corresponding to an integrated luminosity of 135 fb -1 . A new structure is observed with a significance above 5 standard deviations at a mass of 6552 ± 10 (stat) ± 12 (syst) MeV. Another structure with even higher significance is found at a mass of 6927 ± 9 (stat) ± 4 (syst) MeV, which is consistent with the X(6900) resonance reported by the LHCb experiment and confirmed by the ATLAS experiment. Evidence for another new structure, with a local significance of 4.1 standard deviations, is found at a mass of 7287 +20 -18 (stat) ± 5 (syst) MeV. The masses and significances are obtained in a model without considering possible quantum mechanical interference between the resonances. Incorporating this interference provides a better description of the mass spectrum between the resonances and shifts the measured masses by up to 150 MeV.

Multiplicity and transverse momentum dependence of charge-balance functions in pPb and PbPb collisions at LHC energies

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Oct 11, 2023

Measurements of the charge-dependent two-particle angular correlation function in proton-lead (pP... more Measurements of the charge-dependent two-particle angular correlation function in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of √ s NN = 8.16 TeV and lead-lead (PbPb) collisions at √ s NN = 5.02 TeV are reported. The pPb and PbPb datasets correspond to integrated luminosities of 186 nb -1 and 0.607 nb -1 , respectively, and were collected using the CMS detector at the CERN LHC. The chargedependent correlations are characterized by balance functions of same-and oppositesign particle pairs. The balance functions, which contain information about the creation time of charged particle pairs and the development of collectivity, are studied as functions of relative pseudorapidity (∆η) and relative azimuthal angle (∆ϕ), for various multiplicity and transverse momentum (p T ) intervals. A multiplicity dependence of the balance function is observed in ∆η and ∆ϕ for both systems. The width of the balance functions decreases towards high-multiplicity collisions in the momentum region <2 GeV, for pPb and PbPb results. No multiplicity dependence is observed at higher transverse momentum. The data are compared with HYDJET, HIJING and AMPT generator predictions, none of which capture completely the multiplicity dependence seen in the data.

$Research paper thumbnail of Search for inelastic dark matter in events with two displaced muons and missing transverse momentum in proton-proton collisions at $\sqrt{s}$ = 13 TeV$

Search for inelastic dark matter in events with two displaced muons and missing transverse momentum in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search for dark matter in events with a displaced nonresonant muon pair and missing transverse ... more A search for dark matter in events with a displaced nonresonant muon pair and missing transverse momentum is presented. The analysis is performed using an integrated luminosity of 138 fb -1 of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV produced by the LHC in 2016-2018. No significant excess over the predicted backgrounds is observed. Upper limits are set on the product of the inelastic dark matter production cross section σ(pp → A ′ → χ 1 χ 2 ) and the decay branching fraction B(χ 2 → χ 1 µ + µ -), where A ′ is a dark photon and χ 1 and χ 2 are states in the dark sector with near mass degeneracy. This is the first dedicated collider search for inelastic dark matter.

$Research paper thumbnail of Search for resonances in events with photon and jet final states in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV$

Search for resonances in events with photon and jet final states in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

Journal of High Energy Physics, Dec 27, 2023

A bstract A search for resonances in events with the γ +jet final state has been performed using ... more A bstract A search for resonances in events with the γ +jet final state has been performed using proton-proton collision data collected at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV by the CMS experiment at the LHC. The total data analyzed correspond to an integrated luminosity of 138 fb − 1 . Models of excited quarks and quantum black holes are considered. Using a wide-jet reconstruction for the candidate jet, the γ +jet invariant mass spectrum measured in data is examined for the presence of resonances over the standard model continuum background. The background is estimated by fitting this mass distribution with a functional form. The data exhibit no statistically significant deviations from the expected standard model background. Exclusion limits at 95% confidence level on the resonance mass and other parameters are set. Excited light-flavor quarks (excited bottom quarks) are excluded ...

CMS iRPC FEB development and validation

Nuclear instruments and methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment/Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, Apr 1, 2024