2,066 research outputs found
B decays
No full textWe review the prospects for B decay studies at the LHC. Contributing authors: J. Baines, S.P. Baranov, P. Bartalini, M. Beneke, E. Bouhova, G. Buchalla, I. Caprini, F. Charles, J. Charles, Y. Coadou, P. Colangelo, P. Colrain, J. Damet, F. De Fazio, A. Dighe, H. Dijkstra, P. Eerola, N. Ellis, B. Epp, S. Gadomski, P. Galumian, I. Gavrilenko, S. George, V.M. Ghete, V. Gibson, L. Guy, Y. Hasegawa, P. Iengo, A. Jacholkowska, R. Jones, A. Khodjamirian, E. Kneringer, P. Koppenburg, H. Korsmo, N. Labanca, L. Lellouch, M. Lehto, Y. Lemoigne, J. Libby, J. Matias, S. Mele, M. Misiak, A.M. Nairz, T. Nakada, A. Nikitenko, N. Nikitin, A. Nisati, F. Palla, E. Polycarpo, J. Rademacker, F. Rizatdinova, S. Robins, D. Rousseau, W. Ruckstuhl, M.A. Sanchis, O. Schneider, M. Shapiro, C. Shepherd-Themistocleous, P. Sherwood, L. Smirnova, M. Smizanska, A. Starodumov, N. Stepanov, Z. Xie, N. ZaitsevWe review the prospects for B decay studies at the LHC. Contributing authors: J. Baines, S.P. Baranov, P. Bartalini, M. Beneke, E. Bouhova, G. Buchalla, I. Caprini, F. Charles, J. Charles, Y. Coadou, P. Colangelo, P. Colrain, J. Damet, F. De Fazio, A. Dighe, H. Dijkstra, P. Eerola, N. Ellis, B. Epp, S. Gadomski, P. Galumian, I. Gavrilenko, S. George, V.M. Ghete, V. Gibson, L. Guy, Y. Hasegawa, P. Iengo, A. Jacholkowska, R. Jones, A. Khodjamirian, E. Kneringer, P. Koppenburg, H. Korsmo, N. Labanca, L. Lellouch, M. Lehto, Y. Lemoigne, J. Libby, J. Matias, S. Mele, M. Misiak, A.M. Nairz, T. Nakada, A. Nikitenko, N. Nikitin, A. Nisati, F. Palla, E. Polycarpo, J. Rademacker, F. Rizatdinova, S. Robins, D. Rousseau, W. Ruckstuhl, M.A. Sanchis, O. Schneider, M. Shapiro, C. Shepherd-Themistocleous, P. Sherwood, L. Smirnova, M. Smizanska, A. Starodumov, N. Stepanov, Z. Xie, N. Zaitse
Measurements of the production cross-section for a Z boson in association with b- or c-jets in proton–proton collisions at s=13 TeV with the ATLAS detector
No full textThis paper presents a measurement of the production cross-section of a Z boson in association with b- or c-jets, in proton–proton collisions at s=13 TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 140 fb-1. Inclusive and differential cross-sections are measured for events containing a Z boson decaying into electrons or muons and produced in association with at least one b-jet, at least one c-jet, or at least two b-jets with transverse momentum pT>20 GeV and rapidity |y|<2.5. Predictions from several Monte Carlo generators based on next-to-leading-order matrix elements interfaced with a parton-shower simulation, with different choices of flavour schemes for initial-state partons, are compared with the measured cross-sections. The results are also compared with novel predictions, based on infrared and collinear safe jet flavour dressing algorithms. Selected Z+≥1c-jet observables, optimized for sensitivity to intrinsic-charm, are compared with benchmark models with different intrinsic-charm fractions
Search for a fermiophobic Higgs boson in the diphoton decay channel with the ATLAS detector
No full textA search for a fermiophobic Higgs boson using diphoton events produced in proton-proton collisions at a centre-of-mass energy of s=7 TeV is performed using data corresponding to an integrated luminosity of 4.9 fb−1 collected by the ATLAS experiment at the Large Hadron Collider. A specific benchmark model is considered where all the fermion couplings to the Higgs boson are set to zero and the bosonic couplings are kept at the Standard Model values (fermiophobic Higgs model). The largest excess with respect to the background-only hypothesis is found at 125.5 GeV, with a local significance of 2.9 standard deviations, which reduces to 1.6 standard deviations when taking into account the look-elsewhere effect. The data exclude the fermiophobic Higgs model in the ranges 110.0–118.0 GeV and 119.5–121.0 GeV at 95 % confidence level
Study of the B+c → J/ψD+s and B+c → J/ψD*s+ decays with the ATLAS detector
No full textThe decays B-c(+) -> J/psi D-s(+) and B-c(+) -> J/psi D-s*(+) are studied with the ATLAS detector at the LHC using a dataset corresponding to integrated luminosities of 4.9 and 20.6 fb(-1) of pp collisions collected at centre-of-mass energies root s = 7 TeV and 8 TeV, respectively. Signal candidates are identified through J/psi -> mu(+)mu(-) and D-s(()*()+) -> phi pi(+)(gamma/pi(0)) decays. With a two-dimensional likelihood fit involving the B-c(+) reconstructed invariant mass and an angle between the mu(+) and D-s(+) candidate momenta in the muon pair rest frame, the yields of B-c(+) -> J/psi D-s(+) and B-c(+) -> J/psi D-s*(+), and the transverse polarisation fraction in B-c(+) -> J/psi D-s*(+) decay are measured. The transverse polarisation fraction is determined to be Gamma +/-+/-(B-c(+) -> J/psi D-s*(+))/Gamma(B-c(+) -> J/psi D-s*(+)) = 0.38 +/- 0.23 +/- 0.07, and the derived ratio of the branching fractions of the two modes is B-Bc+ -> J/psi D-s*+/B-Bc+ -> J/psi D-s(+) = 2.8(-0.8)(+1.2) +/- 0.3, where the first error is statistical and the second is systematic. Finally, a sample of B-c(+) -> J/psi pi(+) decays is used to derive the ratios of branching fractions B-Bc+ -> J/psi D-s*+/B-Bc+ -> J/psi pi(+) = 3.8 +/- 1.1 +/- 0.4 +/- 0.2 and B-Bc+ -> J/psi D-s*+/B-Bc+ -> J/psi pi(+) = 10.4 +/- 3.1 +/- 1.5 +/- 0.6, where the third error corresponds to the uncertainty of the branching fraction of D-s(+) -> phi(K+ K-)pi(+) decay. The available theoretical predictions are generally consistent with the measurement.ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-015-3743-8</p
Measurement of the relative B-c(+/-)/B-+/- production cross section with the ATLAS detector at root s=8 TeV
No full textThe total cross section and differential cross sections for the production of
B
±
c
mesons, times their branching fraction to
J
/
ψ
π
±
, are measured relative to those for the production of
B
±
mesons, times their branching fraction to
J
/
ψ
K
±
. The data used for this study correspond to an integrated luminosity of
20.3
fb
−
1
of
p
p
collisions recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a center-of-mass energy of
√
s
=
8
TeV
. The measurement is performed differentially in bins of transverse momentum
p
T
for
13
GeV
<
p
T
(
B
±
c
)
<
22
GeV
and
p
T
(
B
±
c
)
>
22
GeV
and in bins of rapidity
y
for
|
y
|
<
0.75
and
0.75
<
|
y
|
<
2.3
. The relative cross section times branching fraction for the full range
p
T
>
13
GeV
and
|
y
|
<
2.3
is
(
0.34
±
0.0
4
stat
+
0.06
−
0.02
sys
±
0.0
1
lifetime
)
%
. The differential measurements suggest that the production cross section of the
B
±
c
decreases faster with
p
T
than the production cross section of the
B
±
, while no significant dependence on rapidity is observed
Search for heavy diboson resonances in semileptonic final states in pp collisions at s=13 TeV with the ATLAS detector
No full textThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/
Jet energy resolution in proton-proton collisions at root s=7 TeV recorded in 2010 with the ATLAS detector
No full textAtlas Collaboration contributor: Paul Douglas Jackson of SLAC National Accelerator Laboratory, Stanford CA, United States of America. Extent: 27p.The measurement of the jet energy resolution is presented using data recorded with the ATLAS detector in proton-proton collisions at √s=7 TeV . The sample corresponds to an integrated luminosity of 35 pb⁻¹. Jets are reconstructed from energy deposits measured by the calorimeters and calibrated using different jet calibration schemes. The jet energy resolution is measured with two different in situ methods which are found to be in agreement within uncertainties. The total uncertainties on these measurements range from 20 % to 10 % for jets within |y|<2.8 and with transverse momenta increasing from 30 GeV to 500 GeV. Overall, the Monte Carlo simulation of the jet energy resolution agrees with the data within 10 %.The ATLAS Collaboratio
Muon reconstruction performance of the ATLAS detector in proton--proton collision data at s√=13 TeV
No full text29 pages inlcuding cover page plus author list (45 pages total), 12 figures, 3 tables, submitted to Eur. Phys. J. C. See paper for full list of authors.International audienceThis article documents the performance of the ATLAS muon identification and reconstruction using the first LHC dataset recorded at s√ = 13 TeV in 2015. Using a large sample of J/ψ→μμ and Z→μμ decays from 3.2 fb−1 of pp collision data, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. The reconstruction efficiency is measured to be close to 99% over most of the covered phase space (|η|2.2, the pT resolution for muons from Z→μμ decays is 2.9% while the precision of the momentum scale for low-pT muons from J/ψ→μμ decays is about 0.2%
Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
No full textIn the version of this article initially published, the ATLAS Collaboration
author names, affiliations and acknowledgements were omitted and
have now been included in the HTML and PDF versions of the article
Study of B c + → J / ψ D s + and B c + → J / ψ D s ∗ + decays in pp collisions at √s = 13 TeV with the ATLAS detector
No full textA study of B+
c → J/ψD+
s and B+
c → J/ψD∗+
s decays using 139 fb−1 of integrated luminosity collected with the ATLAS detector from √
s = 13 TeV pp collisions
at the LHC is presented. The ratios of the branching fractions of the two decays to the
branching fraction of the B+
c → J/ψπ+ decay are measured: B(B+
c → J/ψD+
s
)/B(B+
c →
J/ψπ+) = 2.76 ± 0.47 and B(B+
c → J/ψD∗+
s
)/B(B+
c → J/ψπ+) = 5.33 ± 0.96. The ratio
of the branching fractions of the two decays is found to be B(B+
c → J/ψD∗+
s
)/B(B+
c →
J/ψD+
s
) = 1.93 ± 0.26. For the B+
c → J/ψD∗+
s decay, the transverse polarization fraction,
Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements
exceeds that in all previous studies of these decays. These results supersede those obtained
in the earlier ATLAS study of the same decays with √s = 7 and 8 TeV pp collision data. A
comparison with available theoretical predictions for the measured quantities is presented
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