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 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 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.

scholarly journals Search for heavy neutral leptons in $$W^+\rightarrow \mu ^{+}\mu ^{\pm }\, \text {jet}$$ decays

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Mass Range ◽  
Lepton Number ◽  
Heavy Neutrino ◽  
Proton Collision ◽  
Final State ◽  
Data Set ◽  
Proton Proton ◽  
Upper Limits ◽  
The Standard Model ◽  
Proton Proton Collision

AbstractA search is performed for heavy neutrinos in the decay of a W boson into two muons and a jet. The data set corresponds to an integrated luminosity of approximately $$3.0\, \text {fb} ^{-1} $$ 3.0 fb - 1 of proton–proton collision data at centre-of-mass energies of 7 and $$8\, \text {TeV} $$ 8 TeV collected with the LHCb experiment. Both same-sign and opposite-sign muons in the final state are considered. Data are found to be consistent with the expected background. Upper limits on the coupling of a heavy neutrino with the Standard Model neutrino are set at $$95\%$$ 95 % confidence level in the heavy-neutrino mass range from 5 to $$50\, \text {GeV/}c^2 $$ 50 GeV/ c 2 . These are of the order of $$10^{-3}$$ 10 - 3 for lepton-number-conserving decays and of the order of $$10^{-4}$$ 10 - 4 for lepton-number-violating heavy-neutrino decays.

scholarly journals Measurements of inclusive and differential cross-sections of combined $$ t\overline{t}\gamma $$ and tWγ production in the eμ channel at 13 TeV with the ATLAS detector

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Cross Sections ◽  
Differential Cross ◽  
Theoretical Calculations ◽  
Top Quarks ◽  
Atlas Detector ◽  
Proton Collision ◽  
Differential Cross Sections ◽  
Proton Proton ◽  
Fiducial Volume ◽  
Proton Proton Collision

Abstract Inclusive and differential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb−1. The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13 TeV. The measurements are performed in a fiducial volume defined at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b-tagged, are selected. The fiducial cross-section is measured to be $$ {39.6}_{-2.3}^{+2.7} $$ 39.6 − 2.3 + 2.7 fb. Differential cross-sections as functions of several observables are compared with state-of-the-art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and angular separations between the two leptons in the event. All measurements are in agreement with the predictions from the Standard Model.

scholarly journals Measurement of cross sections and couplings of the Higgs boson in fermionic decay modes with the ATLAS detector

2018 ◽  
Vol 182 ◽  
pp. 02119
Author(s):  
Liaoshan Shi
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Cross Sections ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Proton Proton Collision ◽  
The Cross

In this report, we present the latest ATLAS results on the measurement of the cross sections and couplings of the Higgs boson in the fermionic decay modes, H → μ+μ-, H → τ+τ- and H → bb. The searches are performed with proton-proton collision data delivered by the Large Hadron Collider during Run 1 and the first two years of Run 2 at √s = 7, 8 and 13 TeV.

scholarly journals Search for the doubly charmed baryon $$\Xi_{cc}^+$$

2019 ◽  
Vol 63 (2) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Production Cross ◽  
Branching Fraction ◽  
Mass Range ◽  
Proton Collision ◽  
Final State ◽  
Momentum Range ◽  
Proton Proton ◽  
Charmed Baryon ◽  
Upper Limits ◽  
Lhcb Detector

AbstractA search for the doubly charmed baryon $$\Xi_{cc}^+$$Ξcc+ is performed through its decay to the $$\Lambda_c^ + {K^ -}{\pi ^ +}$$Λc+K−π+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb−1. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the $$\Xi_{cc}^+$$Ξcc+ production cross-section times the branching fraction to that of $$\Lambda_c^ + $$Λc+ and $$\Xi_{cc}^{+ +}$$Ξcc++ baryons. The limits are determined as functions of the $$\Xi_{cc}^+$$Ξcc+ mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.

scholarly journals JET RESULTS AND JET RECONSTRUCTION TECHNIQUES IN p+p AND THEIR PROSPECTS IN HEAVY-ION COLLISIONS IN ATLAS

2011 ◽  
Vol 20 (07) ◽  
pp. 1545-1550
Author(s):  
◽  
MARTIN SPOUSTA
Keyword(s):  
Cross Sections ◽  
Heavy Ion Collisions ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Ion Collisions ◽  
Expected Performance ◽  
Jet Shapes ◽  
Jet Cross Sections

We present the measurement of jet production performed with the ATLAS detector in proton-proton collisions at center-of-mass energy of 7 TeV, using an integrated luminosity of 17 nb−1. We show the inclusive jet cross sections and jet shapes. The expected performance and strategy for the jet reconstruction in heavy ion collisions is also discussed.

scholarly journals Observation and measurements of vector-boson scattering with the ATLAS detector

2020 ◽  
Vol 35 (34n35) ◽  
pp. 2044002
Author(s):  
Ondřej Penc
Keyword(s):  
Cross Sections ◽  
Vector Boson ◽  
Center Of Mass ◽  
New Physics ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Number Of Generators ◽  
Text Production ◽  
Vector Boson Scattering ◽  
Electroweak Boson

The scattering of electroweak bosons tests the gauge structure of the Standard Model and is sensitive to anomalous quartic gauge couplings. In this paper, we present recent results on vector-boson scattering from the ATLAS experiment using proton–proton collisions with a center-of-mass energy of 13 TeV at the LHC. This includes the observation of [Formula: see text], [Formula: see text], and same-sign [Formula: see text] production via vector-boson scattering along with a measurement of [Formula: see text] production ([Formula: see text] denotes [Formula: see text] or [Formula: see text] boson) in semileptonic final states. The results can be used to constrain new physics that manifests as anomalous electroweak-boson self-interactions. Finally, predicted cross-sections for the electroweak scattering of two same-sign [Formula: see text] bosons in association with two jets are compared for a number of generators.

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