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Showing papers by "Timothy Evans published in 2023"


Peer Review
07 Feb 2023
TL;DR: The Gravitational Wave Open Science Center (Gwosc) as mentioned in this paper has released the O3GK dataset, consisting of the gravitational-wave strain time series that contains the astrophysical signals, together with supporting data useful for their analysis and documentation, tutorials, and analysis software packages.
Abstract: The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in April of 2019 and lasting six months, O3b starting in November of 2019 and lasting five months, and O3GK starting in April of 2020 and lasting 2 weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main dataset, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages.

10 citations


17 Apr 2023
TL;DR: In this article , the authors extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network, and used the nondetection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects.
Abstract: Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects.

6 citations



TL;DR: In this paper , the first study of CP violation in the decay mode B ± → [ K + K − π + π − ] D h ± , with h = K, π , is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9 fb − 1 .
Abstract: The first study of CP violation in the decay mode B ± → [ K + K − π + π − ] D h ± , with h = K, π , is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9 fb − 1 . The analysis is performed in bins of phase space, which are optimised for sensitivity to local CP asymmetries. CP -violating observables that are sensitive to the angle γ 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 B ± → [ K + K − π + π − ] D h ± and B ± → [ π + π − π + π − ] D h ± decays.

1 citations





Journal ArticleDOI
TL;DR: In this article , a measurement of the production ratio of the LHCb detector in the forward rapidity region 2 andlt; y < 4.5 TeV was reported.
Abstract: A bstract We report on a measurement of the $$ {\Lambda}_c^{+} $$ Λ c + to D 0 production ratio in peripheral PbPb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV with the LHCb detector in the forward rapidity region 2 < y < 4 . 5. The $$ {\Lambda}_c^{+} $$ Λ c + ( D 0 ) hadrons are reconstructed via the decay channel $$ {\Lambda}_c^{+} $$ Λ c + → pK − π + ( D 0 → K − π + ) for 2 < p T < 8 GeV/ c and in the centrality range of about 65–90%. The results show no significant dependence on p T , y or the mean number of participating nucleons. They are also consistent with similar measurements obtained by the LHCb collaboration in pPb and Pbp collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV. The data agree well with predictions from PYTHIA in pp collisions at $$ \sqrt{s} $$ s = 5 TeV but are in tension with predictions of the Statistical Hadronization model.



Journal ArticleDOI
TL;DR: In this article , the authors measured the ratio of antiprotons originating from antihyperon decays to prompt production for antiproton momenta between 12 and 12 and found that the anti-hyperon contribution to antipron production is significantly larger than predictions of commonly used hadronic production models.
Abstract: Abstract The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5 $$\,\text {Te\hspace{-1.00006pt}V}$$ Te V incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and $$110\,\text {Ge\hspace{-1.00006pt}V\!/}c $$ 110 Ge V\!/ c . The dominant antihyperon contribution, namely $${\overline{\varLambda }} \rightarrow {\overline{{p}}} {{\pi } ^+} $$ Λ ¯ p ¯ π + decays from promptly produced $$\overline{\varLambda }$$ Λ ¯ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models.

Journal ArticleDOI
TL;DR: In this article , the authors present a method to detect CP violation in the decays of the LHCb experiment using pp collision data corresponding to 6 fb − 1 of the integrated luminosity collected by the LCb experiment.
Abstract: A bstract Searches for CP violation in the decays $$ {D}_{(s)}^{+}\to \eta {\pi}^{+} $$ D s + η π + and $$ {D}_{(s)}^{+}\to {\eta}^{\prime }{\pi}^{+} $$ D s + η π + are performed using pp collision data corresponding to 6 fb − 1 of integrated luminosity collected by the LHCb experiment. The calibration channels $$ {D}_{(s)}^{+}\to \phi {\pi}^{+} $$ D s + ϕ π + are used to remove production and detection asymmetries. The resulting CP -violating asymmetries are $$ {\displaystyle \begin{array}{l}{\mathcal{A}}^{CP}=\left({D}^{+}\to \eta {\pi}^{+}\right)=\left(0.34\pm 0.66\pm 0.16\pm 0.05\right)\%,\\ {}{\mathcal{A}}^{CP}=\left({D}_s^{+}\to \eta {\pi}^{+}\right)=\left(0.32\pm 0.51\pm 0.12\right)\%,\\ {}\begin{array}{l}{\mathcal{A}}^{CP}=\left({D}^{+}\to {\eta}^{\prime }{\pi}^{+}\right)=\left(0.49\pm 0.18\pm 0.06\pm 0.05\right)\%,\\ {}{\mathcal{A}}^{CP}=\left({D}_s^{+}\to {\eta}^{\prime }{\pi}^{+}\right)=\left(0.01\pm 0.12\pm 0.08\right)\%,\end{array}\end{array}} $$ A CP = D + η π + = 0.34 ± 0.66 ± 0.16 ± 0.05 % , A CP = D s + η π + = 0.32 ± 0.51 ± 0.12 % , A CP = D + η π + = 0.49 ± 0.18 ± 0.06 ± 0.05 % , A CP = D s + η π + = 0.01 ± 0.12 ± 0.08 % , where the first uncertainty is statistical, the second is systematic and the third, relevant for the D + channels, is due to the uncertainty on $$ {\mathcal{A}}^{CP}=\left({D}^{+}\to \phi {\pi}^{+}\right) $$ A CP = D + ϕ π + . These measurements, currently the most precise for three of the four channels considered, are consistent with the absence of CP violation. A combination of these results with previous LHCb measurements is presented.


24 May 2023
TL;DR: In this article , the LHCb data was used for the first observation of the associated production of $J/\psi$ and $\mathit{\Upsilon}(1S) mesons in proton-proton collisions.
Abstract: The associated production of prompt $J/\psi$ and $\mathit{\mathit{\Upsilon}}$ mesons in $pp$ collisions at a centre-of-mass energy of $\sqrt{s}=13\,\mathrm{TeV}$ is studied using LHCb data, corresponding to an integrated luminosity of $4\,\mathrm{fb}^{-1}$. The measurement is performed for $J/\psi$ ($\mathit{\Upsilon}$) mesons with a transverse momentum $p_{\mathrm{T}}<10\,(30)\,\mathrm{GeV}/c$ in the rapidity range $2.0

16 Jun 2023
TL;DR: In this paper , the authors measured the $CP$ asymmetries of seven $B^-$ decays to two charm mesons using data corresponding to an integrated luminosity of $9\text{ fb}^{-1}$ of proton-proton collisions collected by the LHCb experiment.
Abstract: The $CP$ asymmetries of seven $B^-$ decays to two charm mesons are measured using data corresponding to an integrated luminosity of $9\text{ fb}^{-1}$ of proton-proton collisions collected by the LHCb experiment. Decays involving a $D^{*0}$ or $D^{*-}_s$ meson are analysed by reconstructing only the $D^0$ or $D^-_s$ decay products. This paper presents the first measurement of $\mathcal{A}^{CP}(B^- \rightarrow D^{*-}_s D^0)$ and $\mathcal{A}^{CP}(B^- \rightarrow D^{-}_s D^{*0})$, and the most precise measurement of the other five $CP$ asymmetries. There is no evidence of $CP$ violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.

24 May 2023
TL;DR: In this paper , the mass difference between the two baryons was measured using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of $9 \, \text{fb}^{-1} , and was found to be
Abstract: The mass difference between the $\Omega^-_b$ and $\Xi^-_b$ baryons is measured using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of $9 \, \text{fb}^{-1}$, and is found to be \begin{equation} m(\Omega^-_b)- m(\Xi^-_b) = 248.54 \pm 0.51 \text{(stat)} \pm 0.38 \text{(syst)} \, \text{MeV}/c^2. \end{equation} The mass of the $\Omega^-_b$ baryon is measured to be \begin{equation} m(\Omega^-_b)= 6045.9 \pm 0.5 \text{(stat)} \pm 0.6 \text{(syst)} \, \text{MeV}/c^2. \end{equation} This is the most precise determination of the $\Omega^-_b$ mass to date. In addition, the production rate of $\Omega^-_b$ baryons relative to that of $\Xi^-_b$ baryons is measured for the first time in $pp$ collisions, using an LHCb dataset collected at a center-of-mass energy of $13 \, \text{TeV}$ and corresponding to an integrated luminosity of $6\,\text{fb}^{-1}$. Reconstructing beauty baryons in the kinematic region $2<\eta<6$ and $p_T<20\,\text{GeV}/c$ with their decays to a $J/\psi$ meson and a hyperon, the ratio \begin{equation} \frac{f_{\Omega^-_b}}{f_{\Xi^-_b}}\times\frac{\mathcal{B}(\Omega^-_b \to J/\psi \Omega^-)}{\mathcal{B}(\Xi^-_b \to J/\psi \Xi^-)} = 0.120 \pm 0.008 \text{(stat)} \pm 0.008 \text{(syst)}, \end{equation} is obtained, where $f_{\Omega^-_b}$ and $f_{\Xi^-_b}$ are the fragmentation fractions of $b$ quarks into $\Omega^-_b$ and $\Xi^-_b$ baryons, respectively, and $\mathcal{B}$ represents the branching fractions of their respective decays.

Journal ArticleDOI
TL;DR: In this paper , the meson production by the LHCb experiment in its fixed-target configuration is presented, where mesons are studied with a beam of 2.5 GHz.
Abstract: Abstract A measurement of $${{D}} ^0$$ D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of $${{D}} ^0$$ D 0 mesons is studied with a beam of 2.5 $$\,\text {Te\hspace{-1.00006pt}V}$$ Te V protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of $$\sqrt{s_{\scriptscriptstyle \text {NN}}} = 68.5\,\,\text {Ge\hspace{-1.00006pt}V} $$ s NN = 68.5 Ge V . The sum of the $${{D}} ^0$$ D 0 and $${\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0$$ D ¯ 0 production cross-section in $$p\text {Ne}$$ p Ne collisions in the centre-of-mass rapidity range $$y^{\star }\in [-2.29, 0]$$ y [ - 2.29 , 0 ] is found to be $$\sigma _{D^{0}}^{y^\star \in [-2.29, 0]} = 48.2 \pm 0.3 \pm 4.5 \,\upmu \text {b}/\text {nucleon}$$ σ D 0 y [ - 2.29 , 0 ] = 48.2 ± 0.3 ± 4.5 μ b / nucleon where the first uncertainty is statistical and the second is systematic. The $${{{D}} ^0}-{{\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0} $$ D 0 - D ¯ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative $$y^{\star }$$ y . The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1 $$\%$$ % intrinsic charm and 10 $$\%$$ % recombination contributions better describe the data than the other models considered.

Journal ArticleDOI
TL;DR: In this paper , the production cross-sections of Υ mesons, namely Υ(1 S ), Υ (2 S ), and Φ(3 S ), in pp collisions at 5 TeV were measured with a data sample corresponding to an integrated luminosity of 9 . 13 ± 0 . 18 pb − 1 collected by the LHCb detector.
Abstract: A bstract The production cross-sections of Υ mesons, namely Υ(1 S ), Υ(2 S ) and Υ(3 S ), in pp collisions at $$ \sqrt{s} $$ s = 5 TeV are measured with a data sample corresponding to an integrated luminosity of 9 . 13 ± 0 . 18 pb − 1 collected by the LHCb detector. The Υ mesons are reconstructed in the decay mode Υ → μ + μ − . Double differential cross-sections times branching fractions, as functions of the transverse momentum p T and the rapidity y of the Υ mesons, are measured in the range p T < 20 GeV/ c and 2 . 0 < y < 4 . 5. The results integrated over these p T and y ranges are $$ \sigma \left(\textrm{Y}(1S)\right)\times \mathcal{B}\left(\textrm{Y}(1S)\to {\mu}^{+}{\mu}^{-}\right)=2101\pm 33\pm 83\ \textrm{pb}, $$$$ \sigma \left(\textrm{Y}(2S)\right)\times \mathcal{B}\left(\textrm{Y}(2S)\to {\mu}^{+}{\mu}^{-}\right)=526\pm 20\pm 21\ \textrm{pb}, $$$$ \sigma \left(\textrm{Y}(3S)\right)\times \mathcal{B}\left(\textrm{Y}(3S)\to {\mu}^{+}{\mu}^{-}\right)=242\pm 16\pm 10\ \textrm{pb}, $$ σ Υ 1 S × B Υ 1 S μ + μ = 2101 ± 33 ± 83 pb , σ Υ 2 S × B Υ 2 S μ + μ = 526 ± 20 ± 21 pb , σ Υ 3 S × B Υ 3 S μ + μ = 242 ± 16 ± 10 pb , where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different Υ states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of Υ(1 S ) at $$ \sqrt{s} $$ s = 5 TeV is updated as well using the directly measured cross-section results from this analysis.


28 Apr 2023
TL;DR: In this paper , the authors performed a study of the branching fraction measurements of the $B^+\to K^0_SK \pi$ invariant mass spectra from both decay modes and showed a rich content of charmonium resonances.
Abstract: A study of the $B^+\to K^0_SK^+K^-\pi^+$ and $B^+\to K^0_SK^+K^+\pi^-$ decays is performed using proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV at the LHCb experiment. The $K^0_SK \pi$ invariant mass spectra from both decay modes reveal a rich content of charmonium resonances. New precise measurements of the $\eta_c$ and $\eta_c(2S)$ resonance parameters are performed and branching fraction measurements are obtained for $B^+$ decays to $\eta_c$, $J/\psi$, $\eta_c(2S)$ and $\chi_{c1}$ resonances. In particular, the first observation and branching fraction measurement of $B^+ \to \chi_{c0} K^0 \pi^+$ is reported as well as first measurements of the $B^+\to K^0K^+K^-\pi^+$ and $B^+\to K^0K^+K^+\pi^-$ branching fractions. Dalitz plot analyses of $\eta_c \to K^0_SK\pi$ and $\eta_c(2S) \to K^0_SK\pi$ decays are performed. A new measurement of the amplitude and phase of the $K \pi$ $S$-wave as functions of the $K \pi$ mass is performed, together with measurements of the $K^*_0(1430)$, $K^*_0(1950)$ and $a_0(1700)$ parameters. Finally, the branching fractions of $\chi_{c1}$ decays to $K^*$ resonances are also measured.

Journal ArticleDOI
TL;DR: In this article , the meson production by the LHCb experiment in its fixed-target configuration is presented, where mesons are studied with a beam of 2.5 GHz.
Abstract: Abstract A measurement of $${{D}} ^0$$ D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of $${{D}} ^0$$ D 0 mesons is studied with a beam of 2.5 $$\,\text {Te\hspace{-1.00006pt}V}$$ Te V protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of $$\sqrt{s_{\scriptscriptstyle \text {NN}}} = 68.5\,\,\text {Ge\hspace{-1.00006pt}V} $$ s NN = 68.5 Ge V . The sum of the $${{D}} ^0$$ D 0 and $${\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0$$ D ¯ 0 production cross-section in $$p\text {Ne}$$ p Ne collisions in the centre-of-mass rapidity range $$y^{\star }\in [-2.29, 0]$$ y [ - 2.29 , 0 ] is found to be $$\sigma _{D^{0}}^{y^\star \in [-2.29, 0]} = 48.2 \pm 0.3 \pm 4.5 \,\upmu \text {b}/\text {nucleon}$$ σ D 0 y [ - 2.29 , 0 ] = 48.2 ± 0.3 ± 4.5 μ b / nucleon where the first uncertainty is statistical and the second is systematic. The $${{{D}} ^0}-{{\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0} $$ D 0 - D ¯ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative $$y^{\star }$$ y . The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1 $$\%$$ % intrinsic charm and 10 $$\%$$ % recombination contributions better describe the data than the other models considered.




13 Apr 2023
TL;DR: In this paper , a flavor-tagged time-dependent angular analysis of the decay of the meson was performed using collision data collected by the LHCb experiment at the center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}.
Abstract: A flavor-tagged time-dependent angular analysis of the decay $B_s^{0}\rightarrow\phi\phi$ is performed using $pp$ collision data collected by the LHCb experiment at $\sqrt{s}=13$ TeV, the center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}. The $\it{CP}$-violating phase and direct $\it{CP}$-violation parameter are measured to be $\phi_{s\bar{s}s} = -0.042 \pm 0.075 \pm 0.009 $ rad and $|\lambda|=1.004\pm 0.030 \pm 0.009 $, respectively, assuming the same values for all polarization states of the $\phi\phi$ 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 $pp$ collisions at center-of-mass energies of 7 and 8 TeV, yielding $\phi_{s\bar{s}s} = -0.074 \pm 0.069 $ rad and $|\lambda|=1.009 \pm 0.030$. This is the most precise study of time-dependent $\it{CP} $ violation in a penguin-dominated $B$ meson decay. The results are consistent with $\it{CP} $ symmetry and with the Standard Model predictions.



02 May 2023
TL;DR: In this article , the branching fraction of the LHCb collision data was measured relative to that of the normalisation mode, and the result was consistent with the Standard Model prediction and with previous measurements.
Abstract: The branching fraction $\mathcal{B}(B^0 \to D^{*-}\tau^+ u_{\tau})$ is measured relative to that of the normalisation mode $B^0 \to D^{*-}\pi^+\pi^-\pi^+$ using hadronic $\tau^+ \to \pi^+\pi^-\pi^+(\pi^0)\bar{ u}_{\tau}$ decays in proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb$^{-1}$. The measured ratio is $\mathcal{B}(B^0 \to D^{*-}\tau^+ u_{\tau})/\mathcal{B}(B^0 \to D^{*-}\pi^+\pi^-\pi^+)= 1.70 \pm 0.10^{+0.11}_{-0.10}$, where the first uncertainty is statistical and the second is related to systematic effects. Using established branching fractions for the $B^0 \to D^{*-}\pi^+\pi^-\pi^+$ and $B^0 \to D^{*-} \mu^+ u_\mu$ modes, the lepton universality test, $\mathcal{R}(D^{*-}) \equiv \mathcal{B}(B^0 \to D^{*-}\tau^+ u_{\tau})/\mathcal{B}(B^0 \to D^{*-} \mu^+ u_\mu)$ is calculated, $$ \mathcal{R}(D^{*-}) = 0.247 \pm 0.015 \pm 0.015 \pm 0.012\, , $$ where the third uncertainty is due to the uncertainties on the external branching fractions. This result is consistent with the Standard Model prediction and with previous measurements.


11 May 2023
TL;DR: In this article , a study of prompt production in proton-lead collisions is performed with the LHCb experiment at a center-of-mass energy per nucleon pair of 8.16 TeV in 2016 in $p$Pb and Pb$p$ collisions with an estimated integrated luminosity of approximately 12.5 and 17.4 nb$-nb$^{-1} , respectively.
Abstract: A study of prompt $\Xi_{c}^{+}$ production in proton-lead collisions is performed with the LHCb experiment at a centre-of-mass energy per nucleon pair of 8.16 TeV in 2016 in $p$Pb and Pb$p$ collisions with an estimated integrated luminosity of approximately 12.5 and 17.4 nb$^{-1}$, respectively. The $\Xi_{c}^{+}$ production cross-section, as well as the $\Xi_{c}^{+}$ to $\Lambda_{c}^{+}$ production cross-section ratio, are measured as a function of the transverse momentum and rapidity and compared to latest theory predictions. The forward-backward asymmetry is also measured as a function of the $\Xi_{c}^{+}$ transverse momentum.