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Nicola Cavallo

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Papers by Nicola Cavallo

Measurement of B+/- meson differential production cross sections in pp and PbPb collisions at sqrt(s[NN]) = 5.02 TeV

The differential production cross sections of B ± mesons are measured via the exclusive decay cha... more The differential production cross sections of B ± mesons are measured via the exclusive decay channels B ± → J/ψ K ± → µ + µ − K ± as a function of transverse momentum in pp and PbPb collisions at a center-of-mass energy √ s NN = 5.02 TeV per nucleon pair with the CMS detector at the LHC. The pp (PbPb) dataset used for this analysis corresponds to an integrated luminosity of 28.0 pb −1 (351 µb −1). The measurement is performed in the B ± meson transverse momentum range of 7 to 50 GeV/c, in the rapidity interval |y| < 2.4. In this kinematic range, a strong suppression of the production cross section by about a factor of two is observed in the PbPb system in comparison to the expectation from pp reference data. These results are compared to theoretical calculations incorporating beauty quark diffusion and energy loss in a quark-gluon plasma.

Measurements of the W boson rapidity, helicity, double-differential cross sections, and charge asymmetry in pp collisions at s=13 TeV

Physical Review D, 2020

Table 52 ; Measurements of t t-bar spin correlations and top quark polarization using dilepton final states in pp collisions at sqrt(s) = 8 TeV

$Research paper thumbnail of Measurement of prompt $\mathrm{D}^0$ meson azimuthal anisotropy in PbPb collisions at $ \sqrt{s_{_\mathrm{NN}}} = $ 5.02 TeV$

Measurement of prompt $\mathrm{D}^0$ meson azimuthal anisotropy in PbPb collisions at $ \sqrt{s_{_\mathrm{NN}}} = $ 5.02 TeV

$Research paper thumbnail of Table 58 ; Correlations between jets and charged particles in PbPb and pp collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV$

Table 58 ; Correlations between jets and charged particles in PbPb and pp collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV

$Research paper thumbnail of Measurements of the ${\mathrm{p}}{\mathrm{p}}\to \mathrm{Z}\mathrm{Z}$ production cross section and the $\mathrm{Z} \to 4\ell$ branching fraction, and constraints on anomalous triple gauge couplings at $\sqrt{s} = $ 13 TeV$

Measurements of the ${\mathrm{p}}{\mathrm{p}}\to \mathrm{Z}\mathrm{Z}$ production cross section and the $\mathrm{Z} \to 4\ell$ branching fraction, and constraints on anomalous triple gauge couplings at $\sqrt{s} = $ 13 TeV

Measurements of the pp → ZZ production cross section and the Z → 4 branching fraction, and constr... more

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

Physical Review D, 2019

Search for bottom-type, vectorlike quark pair production in a fully hadronic final state in proton-proton collisions at s=13 TeV

Physical Review D, 2020

$Research paper thumbnail of Bose-Einstein correlations of charged hadrons in proton-proton collisions at s$$ \\sqrt{s} $$ = 13 TeV$

Bose-Einstein correlations of charged hadrons in proton-proton collisions at s$$ \\sqrt{s} $$ = 13 TeV

Journal of High Energy Physics, 2020

Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from ... more 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 $$ \\sqrt{s} $$ 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 $$ \\sqrt{s} $$ s = 7 TeV, as well as with theoretical predictions.

$Research paper thumbnail of Evidence for $$\\text {W}\\text {W}$$WW production from double-parton interactions in proton–proton collisions at $$\\sqrt{s} = 13 \\,\\text {TeV} $$s=13TeV$

Evidence for $$\\text {W}\\text {W}$$WW production from double-parton interactions in proton–proton collisions at $$\\sqrt{s} = 13 \\,\\text {TeV} $$s=13TeV

The European Physical Journal C, 2020

A search for $$\\text {W}\\text {W}$$WW production from double-parton scattering processes using ... more A search for $$\\text {W}\\text {W}$$WW production from double-parton scattering processes using same-charge electron-muon and dimuon events is reported, based on proton-proton collision data collected at a center-of-mass energy of $$13\\,\\text {TeV} $$13TeV. The analyzed data set corresponds to an integrated luminosity of $$77.4{\\,\\text {fb}^{-1}} $$77.4fb-1, collected using the CMS detector at the LHC in 2016 and 2017. Multivariate classifiers are used to discriminate between the signal and the dominant background processes. A maximum likelihood fit is performed to extract the signal cross section. This leads to the first evidence for $$\\text {W}\\text {W}$$WW production via double-parton scattering, with a significance of 3.9 standard deviations. The measured inclusive cross section is $$1.41\\pm 0.28\\,\\text {(stat)} \\pm 0.28\\,\\text {(syst)} \\,\\text {pb} $$1.41±0.28(stat)±0.28(syst)pb.

Search for light pseudoscalar boson pairs produced from decays of the 125 GeV Higgs boson in final states with two muons and two nearby tracks in pp collisions at s=13TeV

Physics Letters B, 2019

A search is presented for pairs of light pseudoscalar bosons, in the mass range from 4 to 15 GeV,... more A search is presented for pairs of light pseudoscalar bosons, in the mass range from 4 to 15 GeV, produced from decays of the 125 GeV Higgs boson. The decay modes considered are final states that arise when one of the pseudoscalars decays to a pair of tau leptons, and the other one either into a pair of tau leptons or muons. The search is based on proton-proton collisions collected by the CMS experiment in 2016 at a center-of-mass energy of 13 TeV that correspond to an integrated luminosity of 35.9 fb −1. The 2μ2τ and 4τ channels are used in combination to constrain the product of the Higgs boson production cross section and the branching fraction into 4τ final state, σ B, exploiting the linear dependence of the fermionic coupling strength of pseudoscalar bosons on the fermion mass. No significant excess is observed beyond the expectation from the standard model. The observed and expected upper limits at 95% confidence level on σ B, relative to the standard model Higgs boson production cross section, are set respectively between 0.022 and 0.23 and between 0.027 and 0.19 in the mass range probed by the analysis.

Search for Higgs boson pair production in the bbττ final state in proton-proton collisions at (s)=8 TeV

Physical Review D, 2017

Results are presented from a search for production of Higgs boson pairs (HH) where one boson deca... more Results are presented from a search for production of Higgs boson pairs (HH) where one boson decays to a pair of b quarks and the other to a τ lepton pair. This work is based on proton-proton collision data collected by the CMS experiment at √ s = 8 TeV, corresponding to an integrated luminosity of 18.3 fb -1 . Resonant and nonresonant modes of HH production have been probed and no significant excess relative to the background-only hypotheses has been found in either mode. Upper limits on cross sections of the two HH production modes have been set. The results have been combined with previously published searches at √ s = 8 TeV, in decay modes to two photons and two b quarks, as well as to four b quarks, which also show no evidence for a signal. Limits from the combination have been set on resonant HH production by an unknown particle X in the mass range m X = 300 GeV to m X = 1000 GeV. For resonant production of spin 0 (spin 2) particles, the observed 95% CL upper limit is 1.13 pb (1.09 pb) at m X = 300 GeV and to 21 fb (18 fb) at m X = 1000 GeV. For nonresonant HH production, a limit of 43 times the rate predicted by the standard model has been set.

Publisher’s Note: Measurements of differential jet cross sections in proton-proton collisions ats=7 TeVwith the CMS detector [Phys. Rev. D87, 112002 (2013)]

Physical Review D, 2013

Measurements of inclusive jet and dijet production cross sections are presented. Data from LHC pr... more Measurements of inclusive jet and dijet production cross sections are presented. Data from LHC protonproton collisions at ffiffi ffi s p ¼ 7 TeV, corresponding to 5:0 fb À1 of integrated luminosity, have been collected with the CMS detector. Jets are reconstructed up to rapidity 2.5, transverse momentum 2 TeV, and dijet invariant mass 5 TeV, using the anti-k T clustering algorithm with distance parameter R ¼ 0:7. The measured cross sections are corrected for detector effects and compared to perturbative QCD predictions at next-to-leading order, using five sets of parton distribution functions.

$Research paper thumbnail of Measurement of the B^{±} Meson Nuclear Modification Factor in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV$

Measurement of the B^{±} Meson Nuclear Modification Factor in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

Physical review letters, Jan 13, 2017

The differential production cross sections of B^{±} mesons are measured via the exclusive decay c... more The differential production cross sections of B^{±} mesons are measured via the exclusive decay channels B^{±}→J/ψK^{±}→μ^{+}μ^{-}K^{±} as a function of transverse momentum in pp and Pb-Pb collisions at a center-of-mass energy sqrt[s_{NN}]=5.02 TeV per nucleon pair with the CMS detector at the LHC. The pp(Pb-Pb) data set used for this analysis corresponds to an integrated luminosity of 28.0 pb^{-1} (351 μb^{-1}). The measurement is performed in the B^{±} meson transverse momentum range of 7 to 50 GeV/c, in the rapidity interval |y|<2.4. In this kinematic range, a strong suppression of the production cross section by about a factor of 2 is observed in the Pb-Pb system in comparison to the expectation from pp reference data. These results are found to be roughly compatible with theoretical calculations incorporating beauty quark diffusion and energy loss in a quark-gluon plasma.

Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at s = 13 TeV

Physics Letters B, 2017

A search for new physics in energetic, high-multiplicity final states has been performed using pr... more A search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a centerof-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 fb −1. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data.

$Research paper thumbnail of Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb−1 of s = 13 $$ \sqrt{s}=13 $$ TeV pp collision data with the ATLAS detector$

Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb−1 of s = 13 $$ \sqrt{s}=13 $$ TeV pp collision data with the ATLAS detector

Journal of High Energy Physics, 2017

A search for strongly produced supersymmetric particles using signatures involving multiple energ... more A search for strongly produced supersymmetric particles using signatures involving multiple energetic jets and either two isolated same-sign leptons (e or μ), or at least three isolated leptons, is presented. The analysis relies on the identification of b-jets and high missing transverse momentum to achieve good sensitivity. A data sample of proton-proton collisions at $$ \sqrt{s}=13 $$ s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to a total integrated luminosity of 36.1 fb−1, is used for the search. No significant excess over the Standard Model prediction is observed. The results are interpreted in several simplified supersymmetric models featuring R-parity conservation or R-parity violation, extending the exclusion limits from previous searches. In models considering gluino pair production, gluino masses are excluded up to 1.87 TeV at 95% confidence level. When bottom squarks are pair-produced and decay to a chargino and ...

Search for exotic decays of a Higgs boson into undetectable particles and one or more photons

Physics Letters B, 2016

A search is presented for exotic decays of a Higgs boson into undetectable particles and one or t... more A search is presented for exotic decays of a Higgs boson into undetectable particles and one or two isolated photons in pp collisions at a center-of-mass energy of 8 TeV. The data correspond to an integrated luminosity of up to 19.4 fb −1 collected with the CMS detector at the LHC. Higgs bosons produced in gluon-gluon fusion and in association with a Z boson are investigated, using models in which the Higgs boson decays into a gravitino and a neutralino or a pair of neutralinos, followed by the decay of the neutralino to a gravitino and a photon. The selected events are consistent with the background-only hypothesis, and limits are placed on the product of cross sections and branching fractions. Assuming a standard model Higgs boson production cross-section, a 95% confidence level upper limit is set on the branching fraction of a 125 GeV Higgs boson decaying into undetectable particles and one or two isolated photons as a function of the neutralino mass. For this class of models and neutralino masses from 1 to 120 GeV an upper limit in the range of 7 to 13% is obtained. Further results are given as a function of the neutralino lifetime, and also for a range of Higgs boson masses.

PSEUDORAPIDITY AND TRANSVERSE MOMENTUM DEPENDENCE OF CHARGE BALANCE IN Au−Au COLLISIONS AT

International Journal of Modern Physics E, 2007

The charge balance function (BF) is studied in Au − Au collisions at [Formula: see text] using th... more The charge balance function (BF) is studied in Au − Au collisions at [Formula: see text] using the STAR detector. It is observed that within the acceptance (−1.3 < η < 1.3) of STAR Time Projection Chamber (TPC), the BF is independent of the position of the windows of same size, showing that BF is boost-invariant in the TPC accepted region. It is found that the BF measured in an observed window η w , B(δη|η w ), divided by [Formula: see text] is independent of the size and position of the observed window η w . These properties of BF hold for different transverse momenta and the width of BF decreases with the increasing of the latter. The result supports the delayed-hadronization scenario in thermal models.

$Research paper thumbnail of Searches for heavy scalar and pseudoscalar Higgs bosons and for flavor-violating decays of the top quark into a Higgs boson in $\\ mathrm {p}\\ mathrm {p} $ collisions at $\\ sqrt {s}= 8~\\ mathrm {TeV} $$

Searches for heavy scalar and pseudoscalar Higgs bosons and for flavor-violating decays of the top quark into a Higgs boson in $\\ mathrm {p}\\ mathrm {p} $ collisions at $\\ sqrt {s}= 8~\\ mathrm {TeV} $

Searches are presented for heavy scalar (H) and pseudoscalar (A) Higgs bosons posited in the two ... more Searches are presented for heavy scalar (H) and pseudoscalar (A) Higgs bosons posited in the two doublet model (2HDM) extensions of the standard model (SM). These searches are based on a data sample of pp collisions collected with the CMS experiment at the LHC at a center-of-mass energy of √ s = 8 TeV and corresponding to an integrated luminosity of 19.5 fb−1. The decays H → hh and A → Zh, where h denotes an SM-like Higgs boson, lead to events with three or more isolated charged leptons or with a photon pair accompanied by one or more isolated leptons. The search results are presented in terms of the H and A production cross sections times branching fractions and are further interpreted in terms of 2HDM parameters. We place 95% CL cross section upper limits of approximately 7 pb on σB for H → hh and 2 pb for A → Zh. Also presented are the results of a search for the rare decay of the top quark that results in a charm quark and an SM Higgs boson, t → ch, the existence of which would indicate a nonzero flavor-changing Yukawa coupling of the top quark to the Higgs boson. We place a 95% CL upper limit of 0.56% on B(t→ ch). Submitted to Physical Review D c © 2014 CERN for the benefit of the CMS Collaboration. CC-BY-3.0 license ∗See Appendix A for the list of collaboration members ar X iv :1 41 0. 27 51 v1 [ he pex ] 1 0 O ct 2 01 4

Progress report of the machine construction and FEL program on LISA at LNF

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1992

Measurement of B+/- meson differential production cross sections in pp and PbPb collisions at sqrt(s[NN]) = 5.02 TeV

The differential production cross sections of B ± mesons are measured via the exclusive decay cha... more The differential production cross sections of B ± mesons are measured via the exclusive decay channels B ± → J/ψ K ± → µ + µ − K ± as a function of transverse momentum in pp and PbPb collisions at a center-of-mass energy √ s NN = 5.02 TeV per nucleon pair with the CMS detector at the LHC. The pp (PbPb) dataset used for this analysis corresponds to an integrated luminosity of 28.0 pb −1 (351 µb −1). The measurement is performed in the B ± meson transverse momentum range of 7 to 50 GeV/c, in the rapidity interval |y| < 2.4. In this kinematic range, a strong suppression of the production cross section by about a factor of two is observed in the PbPb system in comparison to the expectation from pp reference data. These results are compared to theoretical calculations incorporating beauty quark diffusion and energy loss in a quark-gluon plasma.

Measurements of the W boson rapidity, helicity, double-differential cross sections, and charge asymmetry in pp collisions at s=13 TeV

Physical Review D, 2020

Table 52 ; Measurements of t t-bar spin correlations and top quark polarization using dilepton final states in pp collisions at sqrt(s) = 8 TeV

$Research paper thumbnail of Measurement of prompt $\mathrm{D}^0$ meson azimuthal anisotropy in PbPb collisions at $ \sqrt{s_{_\mathrm{NN}}} = $ 5.02 TeV$

Measurement of prompt $\mathrm{D}^0$ meson azimuthal anisotropy in PbPb collisions at $ \sqrt{s_{_\mathrm{NN}}} = $ 5.02 TeV

$Research paper thumbnail of Table 58 ; Correlations between jets and charged particles in PbPb and pp collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV$

Table 58 ; Correlations between jets and charged particles in PbPb and pp collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV

$Research paper thumbnail of Measurements of the ${\mathrm{p}}{\mathrm{p}}\to \mathrm{Z}\mathrm{Z}$ production cross section and the $\mathrm{Z} \to 4\ell$ branching fraction, and constraints on anomalous triple gauge couplings at $\sqrt{s} = $ 13 TeV$

Measurements of the ${\mathrm{p}}{\mathrm{p}}\to \mathrm{Z}\mathrm{Z}$ production cross section and the $\mathrm{Z} \to 4\ell$ branching fraction, and constraints on anomalous triple gauge couplings at $\sqrt{s} = $ 13 TeV

Measurements of the pp → ZZ production cross section and the Z → 4 branching fraction, and constr... more

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

Physical Review D, 2019

Search for bottom-type, vectorlike quark pair production in a fully hadronic final state in proton-proton collisions at s=13 TeV

Physical Review D, 2020

$Research paper thumbnail of Bose-Einstein correlations of charged hadrons in proton-proton collisions at s$$ \\sqrt{s} $$ = 13 TeV$

Bose-Einstein correlations of charged hadrons in proton-proton collisions at s$$ \\sqrt{s} $$ = 13 TeV

Journal of High Energy Physics, 2020

Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from ... more 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 $$ \\sqrt{s} $$ 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 $$ \\sqrt{s} $$ s = 7 TeV, as well as with theoretical predictions.

$Research paper thumbnail of Evidence for $$\\text {W}\\text {W}$$WW production from double-parton interactions in proton–proton collisions at $$\\sqrt{s} = 13 \\,\\text {TeV} $$s=13TeV$

Evidence for $$\\text {W}\\text {W}$$WW production from double-parton interactions in proton–proton collisions at $$\\sqrt{s} = 13 \\,\\text {TeV} $$s=13TeV

The European Physical Journal C, 2020

A search for $$\\text {W}\\text {W}$$WW production from double-parton scattering processes using ... more A search for $$\\text {W}\\text {W}$$WW production from double-parton scattering processes using same-charge electron-muon and dimuon events is reported, based on proton-proton collision data collected at a center-of-mass energy of $$13\\,\\text {TeV} $$13TeV. The analyzed data set corresponds to an integrated luminosity of $$77.4{\\,\\text {fb}^{-1}} $$77.4fb-1, collected using the CMS detector at the LHC in 2016 and 2017. Multivariate classifiers are used to discriminate between the signal and the dominant background processes. A maximum likelihood fit is performed to extract the signal cross section. This leads to the first evidence for $$\\text {W}\\text {W}$$WW production via double-parton scattering, with a significance of 3.9 standard deviations. The measured inclusive cross section is $$1.41\\pm 0.28\\,\\text {(stat)} \\pm 0.28\\,\\text {(syst)} \\,\\text {pb} $$1.41±0.28(stat)±0.28(syst)pb.

Search for light pseudoscalar boson pairs produced from decays of the 125 GeV Higgs boson in final states with two muons and two nearby tracks in pp collisions at s=13TeV

Physics Letters B, 2019

A search is presented for pairs of light pseudoscalar bosons, in the mass range from 4 to 15 GeV,... more A search is presented for pairs of light pseudoscalar bosons, in the mass range from 4 to 15 GeV, produced from decays of the 125 GeV Higgs boson. The decay modes considered are final states that arise when one of the pseudoscalars decays to a pair of tau leptons, and the other one either into a pair of tau leptons or muons. The search is based on proton-proton collisions collected by the CMS experiment in 2016 at a center-of-mass energy of 13 TeV that correspond to an integrated luminosity of 35.9 fb −1. The 2μ2τ and 4τ channels are used in combination to constrain the product of the Higgs boson production cross section and the branching fraction into 4τ final state, σ B, exploiting the linear dependence of the fermionic coupling strength of pseudoscalar bosons on the fermion mass. No significant excess is observed beyond the expectation from the standard model. The observed and expected upper limits at 95% confidence level on σ B, relative to the standard model Higgs boson production cross section, are set respectively between 0.022 and 0.23 and between 0.027 and 0.19 in the mass range probed by the analysis.

Search for Higgs boson pair production in the bbττ final state in proton-proton collisions at (s)=8 TeV

Physical Review D, 2017

Results are presented from a search for production of Higgs boson pairs (HH) where one boson deca... more Results are presented from a search for production of Higgs boson pairs (HH) where one boson decays to a pair of b quarks and the other to a τ lepton pair. This work is based on proton-proton collision data collected by the CMS experiment at √ s = 8 TeV, corresponding to an integrated luminosity of 18.3 fb -1 . Resonant and nonresonant modes of HH production have been probed and no significant excess relative to the background-only hypotheses has been found in either mode. Upper limits on cross sections of the two HH production modes have been set. The results have been combined with previously published searches at √ s = 8 TeV, in decay modes to two photons and two b quarks, as well as to four b quarks, which also show no evidence for a signal. Limits from the combination have been set on resonant HH production by an unknown particle X in the mass range m X = 300 GeV to m X = 1000 GeV. For resonant production of spin 0 (spin 2) particles, the observed 95% CL upper limit is 1.13 pb (1.09 pb) at m X = 300 GeV and to 21 fb (18 fb) at m X = 1000 GeV. For nonresonant HH production, a limit of 43 times the rate predicted by the standard model has been set.

Publisher’s Note: Measurements of differential jet cross sections in proton-proton collisions ats=7 TeVwith the CMS detector [Phys. Rev. D87, 112002 (2013)]

Physical Review D, 2013

Measurements of inclusive jet and dijet production cross sections are presented. Data from LHC pr... more Measurements of inclusive jet and dijet production cross sections are presented. Data from LHC protonproton collisions at ffiffi ffi s p ¼ 7 TeV, corresponding to 5:0 fb À1 of integrated luminosity, have been collected with the CMS detector. Jets are reconstructed up to rapidity 2.5, transverse momentum 2 TeV, and dijet invariant mass 5 TeV, using the anti-k T clustering algorithm with distance parameter R ¼ 0:7. The measured cross sections are corrected for detector effects and compared to perturbative QCD predictions at next-to-leading order, using five sets of parton distribution functions.

$Research paper thumbnail of Measurement of the B^{±} Meson Nuclear Modification Factor in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV$

Measurement of the B^{±} Meson Nuclear Modification Factor in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

Physical review letters, Jan 13, 2017

The differential production cross sections of B^{±} mesons are measured via the exclusive decay c... more The differential production cross sections of B^{±} mesons are measured via the exclusive decay channels B^{±}→J/ψK^{±}→μ^{+}μ^{-}K^{±} as a function of transverse momentum in pp and Pb-Pb collisions at a center-of-mass energy sqrt[s_{NN}]=5.02 TeV per nucleon pair with the CMS detector at the LHC. The pp(Pb-Pb) data set used for this analysis corresponds to an integrated luminosity of 28.0 pb^{-1} (351 μb^{-1}). The measurement is performed in the B^{±} meson transverse momentum range of 7 to 50 GeV/c, in the rapidity interval |y|<2.4. In this kinematic range, a strong suppression of the production cross section by about a factor of 2 is observed in the Pb-Pb system in comparison to the expectation from pp reference data. These results are found to be roughly compatible with theoretical calculations incorporating beauty quark diffusion and energy loss in a quark-gluon plasma.

Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at s = 13 TeV

Physics Letters B, 2017

A search for new physics in energetic, high-multiplicity final states has been performed using pr... more A search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a centerof-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 fb −1. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data.

$Research paper thumbnail of Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb−1 of s = 13 $$ \sqrt{s}=13 $$ TeV pp collision data with the ATLAS detector$

Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb−1 of s = 13 $$ \sqrt{s}=13 $$ TeV pp collision data with the ATLAS detector

Journal of High Energy Physics, 2017

A search for strongly produced supersymmetric particles using signatures involving multiple energ... more A search for strongly produced supersymmetric particles using signatures involving multiple energetic jets and either two isolated same-sign leptons (e or μ), or at least three isolated leptons, is presented. The analysis relies on the identification of b-jets and high missing transverse momentum to achieve good sensitivity. A data sample of proton-proton collisions at $$ \sqrt{s}=13 $$ s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to a total integrated luminosity of 36.1 fb−1, is used for the search. No significant excess over the Standard Model prediction is observed. The results are interpreted in several simplified supersymmetric models featuring R-parity conservation or R-parity violation, extending the exclusion limits from previous searches. In models considering gluino pair production, gluino masses are excluded up to 1.87 TeV at 95% confidence level. When bottom squarks are pair-produced and decay to a chargino and ...

Search for exotic decays of a Higgs boson into undetectable particles and one or more photons

Physics Letters B, 2016

A search is presented for exotic decays of a Higgs boson into undetectable particles and one or t... more A search is presented for exotic decays of a Higgs boson into undetectable particles and one or two isolated photons in pp collisions at a center-of-mass energy of 8 TeV. The data correspond to an integrated luminosity of up to 19.4 fb −1 collected with the CMS detector at the LHC. Higgs bosons produced in gluon-gluon fusion and in association with a Z boson are investigated, using models in which the Higgs boson decays into a gravitino and a neutralino or a pair of neutralinos, followed by the decay of the neutralino to a gravitino and a photon. The selected events are consistent with the background-only hypothesis, and limits are placed on the product of cross sections and branching fractions. Assuming a standard model Higgs boson production cross-section, a 95% confidence level upper limit is set on the branching fraction of a 125 GeV Higgs boson decaying into undetectable particles and one or two isolated photons as a function of the neutralino mass. For this class of models and neutralino masses from 1 to 120 GeV an upper limit in the range of 7 to 13% is obtained. Further results are given as a function of the neutralino lifetime, and also for a range of Higgs boson masses.

PSEUDORAPIDITY AND TRANSVERSE MOMENTUM DEPENDENCE OF CHARGE BALANCE IN Au−Au COLLISIONS AT

International Journal of Modern Physics E, 2007

The charge balance function (BF) is studied in Au − Au collisions at [Formula: see text] using th... more The charge balance function (BF) is studied in Au − Au collisions at [Formula: see text] using the STAR detector. It is observed that within the acceptance (−1.3 < η < 1.3) of STAR Time Projection Chamber (TPC), the BF is independent of the position of the windows of same size, showing that BF is boost-invariant in the TPC accepted region. It is found that the BF measured in an observed window η w , B(δη|η w ), divided by [Formula: see text] is independent of the size and position of the observed window η w . These properties of BF hold for different transverse momenta and the width of BF decreases with the increasing of the latter. The result supports the delayed-hadronization scenario in thermal models.

$Research paper thumbnail of Searches for heavy scalar and pseudoscalar Higgs bosons and for flavor-violating decays of the top quark into a Higgs boson in $\\ mathrm {p}\\ mathrm {p} $ collisions at $\\ sqrt {s}= 8~\\ mathrm {TeV} $$

Searches for heavy scalar and pseudoscalar Higgs bosons and for flavor-violating decays of the top quark into a Higgs boson in $\\ mathrm {p}\\ mathrm {p} $ collisions at $\\ sqrt {s}= 8~\\ mathrm {TeV} $

Searches are presented for heavy scalar (H) and pseudoscalar (A) Higgs bosons posited in the two ... more Searches are presented for heavy scalar (H) and pseudoscalar (A) Higgs bosons posited in the two doublet model (2HDM) extensions of the standard model (SM). These searches are based on a data sample of pp collisions collected with the CMS experiment at the LHC at a center-of-mass energy of √ s = 8 TeV and corresponding to an integrated luminosity of 19.5 fb−1. The decays H → hh and A → Zh, where h denotes an SM-like Higgs boson, lead to events with three or more isolated charged leptons or with a photon pair accompanied by one or more isolated leptons. The search results are presented in terms of the H and A production cross sections times branching fractions and are further interpreted in terms of 2HDM parameters. We place 95% CL cross section upper limits of approximately 7 pb on σB for H → hh and 2 pb for A → Zh. Also presented are the results of a search for the rare decay of the top quark that results in a charm quark and an SM Higgs boson, t → ch, the existence of which would indicate a nonzero flavor-changing Yukawa coupling of the top quark to the Higgs boson. We place a 95% CL upper limit of 0.56% on B(t→ ch). Submitted to Physical Review D c © 2014 CERN for the benefit of the CMS Collaboration. CC-BY-3.0 license ∗See Appendix A for the list of collaboration members ar X iv :1 41 0. 27 51 v1 [ he pex ] 1 0 O ct 2 01 4

Progress report of the machine construction and FEL program on LISA at LNF

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1992