scholarly journals Azimuthal separation in nearly back-to-back jet topologies in inclusive 2- and 3-jet events in $${\text {p}} {\text {p}} $$ collisions at $$\sqrt{s}=13\,\text {Te}\text {V} $$

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Proton Collision ◽  
Leading Order ◽  
Proton Proton ◽  
Perturbative Quantum Chromodynamics ◽  
Center Of Mass Energy ◽  
Theoretical Predictions ◽  
Proton Proton Collision ◽  
Perturbative Quantum ◽  
Two Jets

Abstract A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, $$\varDelta \phi _{12}$$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 $$13\,\text {Te}\text {V} $$13Te and corresponding to an integrated luminosity of $$35.9{\,\text {fb}^{-1}} $$35.9fb-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 $$177^\circ< \varDelta \phi _{12} < 180^\circ $$177∘<Δϕ12<180∘. The 2- and 3-jet measurements are not simultaneously described by any of models.

scholarly journals Searches for low-mass dimuon resonances

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Cross Sections ◽  
Center Of Mass ◽  
Mass Range ◽  
Higgs Doublet ◽  
Proton Collision ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Lhcb Detector ◽  
Low Mass ◽  
Proton Proton Collision

Abstract Searches are performed for a low-mass dimuon resonance, X, produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using a data sample corresponding to an integrated luminosity of 5.1 fb−1 and collected with the LHCb detector. The X bosons can either decay promptly or displaced from the proton-proton collision, where in both cases the requirements placed on the event and the assumptions made about the production mechanisms are kept as minimal as possible. The searches for promptly decaying X bosons explore the mass range from near the dimuon threshold up to 60 GeV, with nonnegligible X widths considered above 20 GeV. The searches for displaced X → μ+μ− decays consider masses up to 3 GeV. None of the searches finds evidence for a signal and 90% confidence-level exclusion limits are placed on the X → μ+μ− cross sections, each with minimal model dependence. In addition, these results are used to place world-leading constraints on GeV-scale bosons in the two-Higgs-doublet and hidden-valley scenarios.

scholarly journals ELECTROWEAK CORRECTIONS TO THE NEUTRALINO PAIR PRODUCTION AT CERN LHC

2013 ◽  
Vol 28 (17) ◽  
pp. 1350077 ◽  
Author(s):  
A. I. AHMADOV ◽  
M. DEMIRCI
Keyword(s):  
Pair Production ◽  
Cross Sections ◽  
Center Of Mass ◽  
Percent Level ◽  
Proton Collision ◽  
Mass Energy ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Energy Formula ◽  
Proton Proton Collision

We apply the leading and subleading electroweak (EW) corrections to the Drell–Yan process of the neutralino pair production at proton–proton collision, in order to calculate the effects of these corrections on the neutralino pair production at the LHC. We provide an analysis of the dependence of the Born cross-sections for [Formula: see text] and the EW corrections to this process, on the center-of-mass energy [Formula: see text], on the M2–μ mass plane and on the squark mass for the three different scenarios. The numerical results show that the relative correction can be reached to the few tens of percent level as the increment of the center-of-mass energy, and the evaluation of EW corrections is a crucial task for all accurate measurements of the neutralino pair production processes.

scholarly journals Search for type-III seesaw heavy leptons in dilepton final states in pp collisions at $$ \sqrt{s} = 13\,{\text {TeV}} $$ with the ATLAS detector

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Hadron Collider ◽  
Atlas Detector ◽  
Proton Collision ◽  
Final State ◽  
Proton Proton ◽  
Type Iii ◽  
Missing Transverse Momentum ◽  
Proton Proton Collision ◽  
Heavy Leptons ◽  
Two Jets

AbstractA search for the pair production of heavy leptons as predicted by the type-III seesaw mechanism is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV, corresponding to $$ 139\,{\text {fb}}^{-1} $$ 139 fb - 1 of integrated luminosity recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis focuses on the final state with two light leptons (electrons or muons) of different flavour and charge combinations, with at least two jets and large missing transverse momentum. No significant excess over the Standard Model expectation is observed. The results are translated into exclusion limits on heavy-lepton masses, and the observed lower limit on the mass of the type-III seesaw heavy leptons is 790 GeV at 95% confidence level.

scholarly journals Measurements of $${\mathrm{p}} {\mathrm{p}} \rightarrow {\mathrm{Z}} {\mathrm{Z}} $$ production cross sections and constraints on anomalous triple gauge couplings at $$\sqrt{s} = 13\,\text {TeV} $$

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Invariant Mass Distribution ◽  
Production Cross ◽  
Center Of Mass ◽  
Mass Region ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Triple Gauge Couplings ◽  
Theoretical Predictions ◽  
Anomalous Triple Gauge Couplings

AbstractThe production of Z boson pairs in proton–proton ($${\mathrm{p}} {\mathrm{p}} $$ p p ) collisions, $${{\mathrm{p}} {\mathrm{p}} \rightarrow ({\mathrm{Z}}/\gamma ^*)({\mathrm{Z}}/\gamma ^*) \rightarrow 2\ell 2\ell '}$$ p p → ( Z / γ ∗ ) ( Z / γ ∗ ) → 2 ℓ 2 ℓ ′ , where $${\ell ,\ell ' = {\mathrm{e}}}$$ ℓ , ℓ ′ = e or $${{\upmu }}$$ μ , is studied at a center-of-mass energy of 13$$\,\text {TeV}$$ TeV with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137$$\,\text {fb}^{-1}$$ fb - 1 , collected during 2016–2018. The $${\mathrm{Z}} {\mathrm{Z}} $$ Z Z production cross section, $$\sigma _{\text {tot}} ({\mathrm{p}} {\mathrm{p}} \rightarrow {\mathrm{Z}} {\mathrm{Z}} ) = 17.4 \pm 0.3 \,\text {(stat)} \pm 0.5 \,\text {(syst)} \pm 0.4 \,\text {(theo)} \pm 0.3 \,\text {(lumi)} \text { pb} $$ σ tot ( p p → Z Z ) = 17.4 ± 0.3 (stat) ± 0.5 (syst) ± 0.4 (theo) ± 0.3 (lumi) pb , measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region $${60< m_{\ell ^+\ell ^-} < 120\,\text {GeV}}$$ 60 < m ℓ + ℓ - < 120 GeV is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous $${\mathrm{Z}} {\mathrm{Z}} {\mathrm{Z}} $$ Z Z Z and $${{\mathrm{Z}} {\mathrm{Z}} \gamma }$$ Z Z γ couplings.

Recent Mid-Rapidity ALLπ0 Measurements in Longitudinally Polarized Proton-Proton Collision at s = 510 GeV with PHENIX Experiment

2016 ◽  
Vol 40 ◽  
pp. 1660022
Author(s):  
Inseok Yoon
Keyword(s):  
Center Of Mass ◽  
Heavy Ion ◽  
Proton Collision ◽  
Relativistic Heavy Ion Collider ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Helicity Distribution ◽  
Statistical Precision ◽  
Polarized Proton ◽  
Energy Formula

It is one of the important purposes of relativistic heavy ion collider (RHIC) longitudinally polarized proton program to constrain the gluon helicity distribution ([Formula: see text]) to the proton by measuring the double helicity asymmetries ([Formula: see text]) via various probes such as [Formula: see text] ([Formula: see text]). The measurement at center of mass energy, [Formula: see text] GeV has been successfully finished and published. To explore lower x region, where dominant uncertainty remains, new measurements were carried out at an increased [Formula: see text] GeV. At this increased energy central [Formula: see text] measurements can reach a lower x range of [Formula: see text], while the previous can reach x range, [Formula: see text]. Also the statistical precision at the same transverse momentum ([Formula: see text]) is substantially improved due to accumulating about 10 times as much luminosity. Preliminary results of [Formula: see text] are presented. Larger asymmetry is observed at [Formula: see text] GeV than at [Formula: see text] GeV at the same [Formula: see text] which is expected due to evolution.

scholarly journals Measurement of the Higgs Boson Mass in the H → ZZ∗→ 4ℓ and H → γγ Channels with s = 13TeV pp Collisions Using the ATLAS Detector

2018 ◽  
Vol 46 ◽  
pp. 1860052
Author(s):  
N. Bruscino
Keyword(s):  
Higgs Boson ◽  
Hadron Collider ◽  
Center Of Mass ◽  
Atlas Detector ◽  
Boson Mass ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Channels ◽  
Mass Distributions ◽  
Center Of Mass Energy

The mass of the Higgs boson is measured in the [Formula: see text] and in the [Formula: see text] decay channels with [Formula: see text]fb[Formula: see text] of proton-proton collision data from the Large Hadron Collider at a center-of-mass energy of [Formula: see text] TeV recorded by the ATLAS detector in 2015 and 2016. The measured value in the [Formula: see text] channel is [Formula: see text]GeV, while the measured value in the [Formula: see text] channel is [Formula: see text]GeV. The two results have a compatibility of [Formula: see text]. The combined measurement from a simultaneous fit to the invariant mass distributions in the two channels is [Formula: see text]GeV.

scholarly journals Measurements of the differential cross sections of the production of Z + jets and γ + jets and of Z boson emission collinear with a jet in pp collisions at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Differential Cross ◽  
Z Boson ◽  
Center Of Mass ◽  
Z Bosons ◽  
Differential Cross Sections ◽  
Pp Collisions ◽  
Center Of Mass Energy ◽  
Cms Experiment ◽  
Theoretical Predictions

Abstract Measurements of the differential cross sections of Z + jets and γ + jets production, and their ratio, are presented as a function of the boson transverse momentum. Measurements are also presented of the angular distribution between the Z boson and the closest jet. The analysis is based on pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb−1 recorded by the CMS experiment at the LHC. The results, corrected for detector effects, are compared with various theoretical predictions. In general, the predictions at higher orders in perturbation theory show better agreement with the measurements. This work provides the first measurement of the ratio of the differential cross sections of Z + jets and γ + jets production at 13 TeV, as well as the first direct measurement of Z bosons emitted collinearly with a jet.

scholarly journals Dual subtractions

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Renato Maria Prisco ◽  
Francesco Tramontano
Keyword(s):  
Field Theory ◽  
Quantum Field ◽  
Matrix Elements ◽  
Leading Order ◽  
Initial State ◽  
Final State ◽  
Dual Representation ◽  
Subtraction Scheme ◽  
Theoretical Predictions ◽  
Perturbative Quantum

Abstract We propose a novel local subtraction scheme for the computation of Next-to-Leading Order contributions to theoretical predictions for scattering processes in perturbative Quantum Field Theory. With respect to well known schemes proposed since many years that build upon the analysis of the real radiation matrix elements, our construction starts from the loop diagrams and exploits their dual representation. Our scheme implements exact phase space factorization, handles final state as well as initial state singularities and is suitable for both massless and massive particles.

scholarly journals Measuring the quartic Higgs self-coupling at a multi-TeV muon collider

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
M. Chiesa ◽  
F. Maltoni ◽  
L. Mantani ◽  
B. Mele ◽  
F. Piccinini ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Center Of Mass ◽  
Mass Energy ◽  
Simple Analysis ◽  
Proton Proton ◽  
Coupling Interaction ◽  
Center Of Mass Energy ◽  
Muon Collider ◽  
Better Than

Abstract Measuring the shape of the Higgs boson potential is of paramount importance, and will be a challenging task at current as well as future colliders. While the expectations for the measurement of the trilinear Higgs self-coupling are rather promising, an accurate measurement of the quartic self-coupling interaction is presently considered extremely challenging even at a future 100 TeV proton-proton collider. In this work we explore the sensitivity that a muon collider with a center of mass energy in the multi-TeV range and luminosities of the order of 1035cm−2s−1, as presently under discussion, might provide, thanks to a rather large three Higgs-boson production and to a limited background. By performing a first and simple analysis, we find a clear indication that a muon collider could provide a determination of the quartic Higgs self-coupling that is significantly better than what is currently considered attainable at other future colliders.

scholarly journals Measurement of the shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ differential decay rate

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Decay Rate ◽  
Form Factors ◽  
Proton Collision ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Lhcb Detector ◽  
Proton Proton Collision ◽  
Integrated Luminosity

Abstract The shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ differential decay rate is obtained as a function of the hadron recoil parameter using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb−1 collected by the LHCb detector. The $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ decay is reconstructed through the decays $$ {D}_s^{\ast -}\to {D}_s^{-}\gamma $$ D s ∗ − → D s − γ and $$ {D}_s^{-}\to {K}^{-}{K}^{+}{\pi}^{-} $$ D s − → K − K + π − . The differential decay rate is fitted with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) parametrisations of the form factors, and the relevant quantities for both are extracted.

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