130 research outputs found
Reliability of heart rate variability threshold and parasympathetic reactivation after a submaximal exercise test
Observation of Two New Excited Ξb0 States Decaying to Λb0 K-π+
Two narrow resonant states are observed in the Λb0K-π+ mass spectrum using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 6 fb-1. The minimal quark content of the Λb0K-π+ system indicates that these are excited Ξb0 baryons. The masses of the Ξb(6327)0 and Ξb(6333)0 states are m[Ξb(6327)0]=6327.28-0.21+0.23±0.12±0.24 and m[Ξb(6333)0]=6332.69-0.18+0.17±0.03±0.22 MeV, respectively, with a mass splitting of Δm=5.41-0.27+0.26±0.12 MeV, where the uncertainties are statistical, systematic, and due to the Λb0 mass measurement. The measured natural widths of these states are consistent with zero, with upper limits of Γ[Ξb(6327)0]<2.20(2.56) and Γ[Ξb(6333)0]<1.60(1.92) MeV at a 90% (95%) credibility level. The significance of the two-peak hypothesis is larger than nine (five) Gaussian standard deviations compared to the no-peak (one-peak) hypothesis. The masses, widths, and resonant structure of the new states are in good agreement with the expectations for a doublet of 1D Ξb0 resonances
Precision measurement of violation in the penguin-mediated decay
A flavor-tagged time-dependent angular analysis of the decay
is performed using collision data collected
by the LHCb experiment at % at TeV, the center-of-mass energy of
13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}. The
-violating phase and direct -violation parameter are measured
to be rad and
, respectively, assuming the same values
for all polarization states of the system. In these results, the
first uncertainties are statistical and the second systematic. These parameters
are also determined separately for each polarization state, showing no evidence
for polarization dependence. The results are combined with previous LHCb
measurements using collisions at center-of-mass energies of 7 and 8 TeV,
yielding rad and . This is the most precise study of time-dependent violation
in a penguin-dominated meson decay. The results are consistent with
symmetry and with the Standard Model 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-2023-001.html (LHCb
public pages
Measurement of the differential branching fraction
The branching fraction of the rare decay is measured for the first time, in the squared dimuon mass
intervals, , excluding the and regions. The data
sample analyzed was collected by the LHCb experiment at center-of-mass energies
of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of $9\
\mathrm{fb}^{-1}q^{2}q^{2} >15.0\
\mathrm{GeV}^2/c^4$, where theoretical predictions have the smallest model
dependence, agrees with the 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-2022-050.html (LHCb
public pages
Search for beautiful tetraquarks in the <i>ϒ</i>(1<i>S</i>)μ<sup>+</sup>μ<sup>−</sup> invariant-mass spectrum
International audienceThe ϒ(1S)μμ invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two quarks, . The analysis is based on a data sample of pp collisions recorded with the LHCb detector at centre-of-mass energies , 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb. No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range [2.0, 5.0], and the state has rapidity in the range [2.0, 4.5] and transverse momentum less than 15 GeV/c
Measurement of the CKM angle γ using<i> B</i><sup>±</sup> → <i>DK</i><sup>±</sup> with D → K <sub>S</sub> <sup>0</sup> π<sup>+</sup>π<sup>−</sup>, K <sub>S</sub> <sup>0</sup> K<sup>+</sup>K<sup>−</sup> decays
A binned Dalitz plot analysis of decays, with and , is used to perform a
measurement of the CP-violating observables and , which are
sensitive to the Cabibbo-Kobayashi-Maskawa angle . The analysis is
performed without assuming any decay model, through the use of information
on the strong-phase variation over the Dalitz plot from the CLEO collaboration.
Using a sample of proton-proton collision data collected with the LHCb
experiment in 2015 and 2016, and corresponding to an integrated luminosity of
2.0, the values of the CP violation parameters are found to
be , , , and . The first
uncertainty is statistical, the second is systematic, and the third is due to
the uncertainty on the strong-phase measurements. These values are used to
obtain \gamma = \left(87\,^{+11}_{-12}\right)^\circ, , and , where is the ratio
between the suppressed and favoured -decay amplitudes and is the
corresponding strong-interaction phase difference. This measurement is combined
with the result obtained using 2011 and 2012 data collected with the \lhcb
experiment, to give \gamma = \left(80\,^{+10}_{\,-9}\right)^\circ, , and .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2018-017.html.
Version 2 includes minor changes made during journal revie
Autonomic nervous system and hypothalamic–pituitary–adrenal axis response to experimentally induced cold pain in adolescent non-suicidal self-injury – study protocol
Precise determination of the B-s(0)-B-s(-0) oscillation frequency
Mesons comprising a beauty quark and a strange quark can oscillate between
particle (B0s) and antiparticle (B0s) flavour eigenstates, with a frequency
given by the mass difference between heavy and light mass eigenstates, deltams.
Here we present ameasurement of deltams using B0s2DsPi decays produced in
proton-proton collisions collected with the LHCb detector at the Large Hadron
Collider. The oscillation frequency is found to be deltams = 17.7683 +- 0.0051
+- 0.0032 ps-1, where the first uncertainty is statistical and the second
systematic. This measurement improves upon the current deltams precision by a
factor of two. We combine this result with previous LHCb measurements to
determine deltams = 17.7656 +- 0.0057 ps-1, which is the legacy measurement of
the original LHCb detector.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-005.html (LHCb
public pages
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Study of the and states in decays
The decays are studied using a data
set corresponding to an integrated luminosity of 9fb collected with the
LHCb detector in proton-proton collisions between 2011 and 2018. Precise
measurements of the ratios of branching fractions with the intermediate
, and states are reported. The decay
of with is observed for the first time with a significance of 5.1
standard deviations. The mass differences between the ,
and states are measured to be resulting in the
most precise determination of the mass. The width of the
state is found to be below 5.2MeV at 90\% confidence level. The
Breit-Wigner width of the state is measured to be which is inconsistent with zero by 5.5 standard deviations
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