3,763 research outputs found
Search for CP violation in B^0 -> J/psi K^0_S decays with first LHCb data
We report a measurement of the CP violation in B^0 -> J/\psi K^0_S decays. We
perform a time-dependent analysis of the decays reconstructed in 35/pb of LHCb
data that was taken in 2010. We measure the CP asymmetry parameterComment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011),
Paris, France, November 14-18 2011, 3 pages, 3 figure
Study of coherent charmonium production in ultra-peripheral lead-lead collisions
The cross-sections of coherent and production in
ultra-peripheral PbPb collisions at a nucleon-nucleon centre-of-mass energy of
are measured using a data sample corresponding to an
integrated luminosity of , collected by the LHCb
experiment in 2018. The differential cross-sections are measured separately as
a function of transverse momentum and rapidity in the nucleus-nucleus
centre-of-mass frame for and mesons. The
integrated cross-sections are measured to be and
, where the first listed uncertainty is statistical, the
second systematic and the third due to the luminosity determination. The
cross-section ratio is measured to be
, where the first uncertainty is statistical and the second
is systematic. These results are compatible with theoretical predictions.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-012.html (LHCb
public pages
A study of violation in the decays () and
The first study of violation in the decay mode
, with , is presented, exploiting
a data sample of proton-proton collisions collected by the LHCb experiment that
corresponds to an integrated luminosity of fb. The analysis is
performed in bins of phase space, which are optimised for sensitivity to local
asymmetries. -violating observables that are sensitive to the
angle of the Unitarity Triangle are determined. The analysis requires
external information on charm-decay parameters, which are currently taken from
an amplitude analysis of LHCb data, but can be updated in the future when
direct measurements become available. Measurements are also performed of
phase-space integrated observables for and
decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-037.html (LHCb
public pages
LHCb: Beam Pipe
The proton beams circulate in the accelerator in Ultra High Vacuum to make them interact only with each other when colliding at the interaction point. A special beam pipe "holds" the vacuum where they pass through the LHCb detector:it has to be mechanically very strong to stand the difference in pressure between the vacuum inside it and the air in the cavern but also be as transparent as possible for the particles originating in the proton−proton collisions
Search for rare decays of mesons into two muons
A search for the very rare decay is performed using data
collected by the LHCb experiment in proton-proton collisions at ,
8 and , corresponding to an integrated luminosity of
. The search is optimised for mesons from decays but is also sensitive to mesons from other sources. No
evidence for an excess of events over the expected background is observed. An
upper limit on the branching fraction of this decay is set at at a CL. This represents the
world's most stringent limit, constraining models of physics beyond the
Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-029.html (LHCb
public pages
Search for direct violation in charged charmless decays
Measurements of asymmetry in charmless decays are presented,
where and denote a pseudoscalar and a vector meson, respectively. Five
different decays from four final states, , , and are analyzed. The measurements are based on a method that does
not require full amplitude analyses, and are performed using proton-proton
collision data at a center-of-mass energy of 13 TeV collected by LHCb between
2015 and 2018, corresponding to an integrated luminosity of 5.9 fb. In
the -wave, in the region dominated by the decay, a asymmetry of \mbox{A_{CP}\pm\pm 0.011} is measured, where the first uncertainty is statistical and
the second is systematic. This is the first observation of violation in
this process. For the other four decay channels, in regions dominated by the
, ,
and
decays, asymmetries in the -wave compatible with zero are
measured.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-050.htm
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
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