arXiv subjects

P. Adlarson

Publications and source records attributed to P. Adlarson.

At least 487 records · Page 27Linked to original sources

arXiv2024

Search for $X(1870)$ via the decay $J/ψ\to ωK^+ K^-η$

Using a sample of $(10087\pm 44)\times10^{6}$ $J/ψ$ events collected by the BESIII detector at the BEPCII collider, we search for the decay $X(1870)\to K^+ K^-η$ via the $J/ψ\to ωK^+ K^- η$ process for the first time. No significant $X(1870)$ signal is observed. The upper limit on the branching fraction of the decay $ J/ψ\to ωX(1870) \toωK^+ K^- η$ is determined to be $9.55\times 10^{-7}$ at the $90\%$ confidence level. In addition, the branching faction $B(J/ψ\toωK^+ K^- η)$ is measured to be $(3.33\pm0.02(\rm{stat.})\pm 0.12(\rm{syst.}))\times 10^{-4}$.

hep-ex↗

arXiv2024

Observation of $η_{c}$(1S, 2S) and $χ_{cJ}$ decays to 2$(π^{+}π^{-})η$ via $ψ$(3686) radiative transitions

Based on $2.7 \times 10^9~ψ(3686)$ decays collected with the BESIII detector, the radiative decay $ψ(3686)\to\gamma2(π^{+}π^{-})η$ is investigated to measure properties of S- and P-wave charmonium states. The branching fraction of the decay $η_{c}(1S) \to 2(π^{+}π^{-})η$, which is found to have a strong dependence on the interference pattern between $η_c(1S)$ and non-$η_c(1S)$ processes, is measured in both destructive and constructive interference scenarios for the first time. The mass and width of the $η_{c}(1S)$ are measured to be $M=(2984.14 \pm 0.13 \pm 0.38)$ MeV/$c^{2}$ and $Γ=(28.82 \pm 0.11 \pm 0.82)$ MeV, respectively. Clear signals for the decays of the $χ_{cJ}(J=0,1,2)$ and the $η_{c}(2S)$ to $2(π^{+}π^{-})η$ are also observed for the first time, and the corresponding branching fractions are measured. The ratio of the branching fractions between the $η_{c}(2S)$ and $η_{c}(1S)$ decays is significantly lower than the theoretical prediction, which might suggest different dynamics in their decays.

hep-ex↗

arXiv2024

Observation of $Λ_{b}^{0} \to Λ_{c}^{+} \bar{D}^{()0} K^{-}$ and $Λ_{b}^{0} \to Λ_{c}^{+} D_{s}^{-}$ decays

The decays $Λ_b^0 \to Λ_c^+\bar{D}^{(*)0}K^-$ and $Λ_b^0 \to Λ_c^+ D_s^{*-}$ are observed for the first time, in proton-proton collision data at $\sqrt{s}=13$TeV corresponding to an integrated luminosity of 5.4 fb${}^{-1}$ collected with the LHCb detector. Their ratios of branching fractions with respect to the $Λ_b^0\!\toΛ_c^+\mathrm{D}_s^-$ mode are measured to be \begin{align*} \begin{split} \frac{\mathcal{B}(Λ_b^0 \to Λ_c^+\bar{D}^0 K^-)}{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^-)} & = 0.1908 {}_{-0.0034}^{+0.0036} {}_{-0.0018}^{+0.0016} \pm 0.0038 \frac{\mathcal{B}(Λ_b^0 \to Λ_c^+\bar{D}^{*0} K^-)}{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^-)} & = 0.589 {}_{-0.017}^{+0.018} {}_{-0.018}^{+0.017} \pm 0.012 \frac{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^{*-})}{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^-)} & = 1.668 \pm 0.022 {}_{-0.055}^{+0.061}\ , \end{split} \end{align*} where the first uncertainties are statistical, the second systematic, and the third, for the $Λ_b^0 \to Λ_c^+ \bar{D}^{(*)0} K^-$ decays, are due to the uncertainties on the branching fractions of the $D_s^- \to K^- K^+ π^-$ and $\bar{D}^0 \to K^+π^-$ decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in $Λ_b^0 \to Λ_c^+ \bar{D}^{(*)0}K^-$ decay channels.

hep-ex↗

arXiv2024

Measurements of the branching fractions of the $P$-wave charmonium spin-singlet state $h_c(^1P_1) \to h^+ h^-π^0/η$

Based on $(2712.4\pm 14.3)\times10^{6}$ $ψ(3686)$ events, we investigate four hadronic decay modes of the $P$-wave charmonium spin-singlet state $h_c(^1P_1) \to h^+ h^- π^0/η$ ($h=π$ or $K$) via the process $ψ(3686) \to π^{0}h_c$ at BESIII. The $h_c \to π^+ π^- π^0$ decay is observed with a significance of 9.6$σ$ after taking into account systematic uncertainties. Evidences for $h_c \to K^+ K^- π^0$ and $h_c \to K^+ K^- η$ are found with significances of $3.5σ$ and $3.3σ$, respectively, after considering the systematic uncertainties. The branching fractions of these decays are measured to be $\mathcal{B}(h_c \to π^+ π^- π^0)=(1.36\pm0.16\pm0.14)\times10^{-3}$, $\mathcal{B}(h_c \to K^+ K^- π^0)=(3.26\pm0.84\pm0.36)\times10^{-4}$, and $\mathcal{B}(h_c \to K^+ K^- η)=(3.13\pm1.08\pm0.38)\times10^{-4}$, where the first uncertainties are statistical and the second are systematic. No significant signal of $h_c\toπ^+π^-η$ is found, and the upper limit of its decay branching fraction is determined to be $\mathcal{B}(h_c\toπ^+π^-η) < 4.0 \times 10^{-4}$ at 90% confidence level.

hep-ex↗

arXiv2024

Multiplicity dependence of $σ_{ψ(2S)}/σ_{J/ψ}$ in $pp$ collisions at $\sqrt{s}=13$ TeV

The ratio of production cross-sections of $ψ(2S)$ over $J/ψ$ mesons as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy $\sqrt{s}=13$ TeV is measured with a data sample collected by the LHCb detector, corresponding to an integrated luminosity of 658 pb$^{-1}$. The ratio is measured for both prompt and non-prompt $ψ(2S)$ and $J/ψ$ mesons. When there is an overlap between the rapidity ranges over which multiplicity and charmonia production are measured, a multiplicity-dependent modification of the ratio is observed for prompt mesons. No significant multiplicity dependence is found when the ranges do not overlap. For non-prompt production, the $ψ(2S)-to-J/ψ$ production ratio is roughly independent of multiplicity irrespective of the rapidity range over which the multiplicity is measured. The results are compared to predictions of the co-mover model and agree well except in the low multiplicity region. The ratio of production cross-sections of $ψ(2S)$ over $J/ψ$ mesons are cross-checked with other measurements in di-lepton channels and found to be compatible.

hep-ex↗

arXiv2024

Evidence of the Singly Cabibbo Suppressed decay $Λ_c^+\to pπ^0$

Evidence for the singly Cabibbo suppressed decay $Λ_c^+\to pπ^0$ is reported for the first time with a statistical significance of $3.7σ$ based on 6.0 $\mathrm{fb}^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider. The absolute branching fraction of $Λ_c^+\to pπ^0$ is measured to be $(1.56^{+0.72}_{-0.58}\pm0.20)\times 10^{-4}$. Combining with the branching fraction of $Λ_c^+\to nπ^+$, $(6.6\pm1.3)\times10^{-4}$, the ratio of the branching fractions of $Λ_c^+\to nπ^+$ and $Λ_c^+\to pπ^0$ is calculated to be $3.2^{+2.2}_{-1.2}$. As an important input for the theoretical models describing the decay mechanisms of charmed baryons, our result indicates that the non-factorizable contributions play an essential role and their interference with the factorizable contributions should not be significant. In addition, the absolute branching fraction of $Λ_c^+\to pη$ is measured to be $(1.63\pm0.31_{\rm stat}\pm0.11_{\rm syst}) \times10^{-3}$.

hep-ex↗

arXiv2024

Study of the decays $χ_{cJ} \rightarrow Λ\barΛϕ$

Based on $(2712.4 \pm 14.3) \times 10^{6}$ $ e^{+}e^{-}\toψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, we report the first evidence of $χ_{c0}\to Λ\bar Λϕ$ decays and the first observation of $χ_{c1,2}\to Λ\bar Λϕ$ decays, with significances of $4.5σ$, $11.3σ$ and $13.0σ$, respectively. The decay branching fractions of $χ_{c0,1,2}\to Λ\bar Λϕ$ are measured to be $( 2.99\pm1.24\pm0.19) \times 10^{-5}$, $(6.01\pm0.90\pm0.40 )\times 10^{-5}$, and $(7.13\pm0.81\pm0.36) \times 10^{-5}$, where the first uncertainties are statistical and the second systematic. No obvious enhancement near the $Λ\barΛ$ production threshold or excited $Λ$ state is found in the $Λϕ$ (or $\barΛϕ$) system.

hep-ex↗

arXiv2024

Measurement of absolute branching fractions of $D_s^+$ hadronic decays

Using $e^+ e^-$ collision data collected at the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of $7.33~{\rm fb}^{-1}$, we determine the absolute branching fractions of fifteen hadronic $D_s^{+}$ decays with a double-tag technique. In particular, we make precise measurements of the branching fractions $\mathcal{B}(D_s^+ \to K^+ K^- π^+)=(5.49 \pm 0.04 \pm 0.07)\%$, $\mathcal{B}(D_s^+ \to K_S^0 K^+)=(1.50 \pm 0.01 \pm 0.01)\%$ and $\mathcal{B}(D_s^+ \to K^+ K^- π^+ π^0)=(5.50 \pm 0.05 \pm 0.11)\%$, where the first uncertainties are statistical and the second ones are systematic. The \emph{CP} asymmetries in these decays are also measured and all are found to be compatible with zero.

hep-ex↗

arXiv2024

Measurement of associated $J/ψ$-$ψ(2S)$ production cross-section in $pp$ collisions at $\sqrt{s}=13$ TeV

The cross-section of associated $J/ψ$-$ψ(2S)$ production in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb$^{-1}$, collected by the LHCb experiment. The measurement is performed for both $J/ψ$ and $ψ(2S)$ mesons having transverse momentum $p_{\text{T}}<14$ GeV/$c$ and rapidity $2.0<y<4.5$, assuming negligible polarisation of the $J/ψ$ and $ψ(2S)$ mesons. The production cross-section is measured to be $4.5\pm0.7\pm0.3$ nb, where the first uncertainty is statistical and the second systematic. The differential cross-sections are measured as functions of several kinematic variables of the $J/ψ$-$ψ(2S)$ candidates. The results are combined with a measurement of $J/ψ$-$J/ψ$ production, giving a cross-section ratio between $J/ψ$-$ψ(2S)$ and $J/ψ$-$J/ψ$ production of $0.274\pm0.044\pm0.008$, where the first uncertainty is statistical and the second systematic.

hep-ex↗

arXiv2024

Determination of the number of $ψ(3686)$ events taken at BESIII

The number of $ψ(3686)$ events collected by the BESIII detector during the 2021 run period is determined to be $(2259.3\pm 11.1)\times 10^6$ by counting inclusive $ψ(3686)$ hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of $ψ(3686)$ events collected during the 2009 and 2012 run periods are updated to be $(107.7\pm0.6)\times 10^6$ and $(345.4\pm 2.6)\times 10^6$, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of $ψ(3686)$ events in the three data samples is $(2712.4\pm14.3)\times10^6$.

hep-ex↗

arXiv2024

Measurement of the Branching Fraction of $B^{0} \rightarrow J/ψπ^{0}$ Decays

The ratio of branching fractions between $B^{0} \rightarrow J/ψπ^{0}$ and $B^{+} \rightarrow J/ψK^{*+}$ decays is measured with proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb$^{-1}$. The measured value is $\frac{\mathcal{B}_{B^{0} \rightarrow J/ψπ^{0}}}{\mathcal{B}_{B^{+} \rightarrow J/ψK^{*+}}} = (1.153 \pm 0.053 \pm 0.048 ) \times 10^{-2}$, where the first uncertainty is statistical and the second is systematic. The branching fraction for $B^{0} \rightarrow J/ψπ^{0}$ decays is determined using the branching fraction of the normalisation channel, resulting in $\mathcal{B}_{B^{0} \rightarrow J/ψπ^{0}} = (1.670 \pm 0.077 \pm 0.069 \pm 0.095) \times 10^{-5}$, where the last uncertainty corresponds to that of the external input. This result is consistent with the current world average value and competitive with the most precise single measurement to date.

hep-ex↗

arXiv2024

Study of the decays $χ_{cJ}\toΛ\barΛω$

Using $(27.12\pm 0.14)\times10^{8}$ $ψ(3686)$ events collected with the BESIII detector, we present the first observation of the decays $χ_{cJ}\toΛ\barΛω$, where $J=0, 1, 2$, with statistical significances of $11.7 σ, 11.2 σ$, and $11.8 σ$. The branching fractions of these decays are determined to be $\mathcal{B}(χ_{c0}\toΛ\barΛω)=({2.37 \pm 0.22 \pm 0.23}) \times 10^{-4}$, $\mathcal{B}(χ_{c1}\toΛ\barΛω)=({1.01 \pm 0.10 \pm 0.11}) \times 10^{-4}$, and $\mathcal{B}(χ_{c2}\toΛ\barΛω)=({1.40 \pm 0.13 \pm 0.17}) \times 10^{-4}$, where the first uncertainties are statistical and the second are systematic. We observe no clear intermediate structures.

hep-ex↗

arXiv2024

Search for $B_c^+\toπ^+μ^+μ^-$ decays and measurement of the branching fraction ratio ${\cal B}(B_c^+\toψ(2S)π^+)/{\cal B}(B_c^+\to J/ψπ^+)$

The first search for nonresonant $B_c^+\toπ^+μ^+μ^-$ decays is reported. The analysis uses proton-proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio ${\cal B}(B_c^+\toπ^+μ^+μ^-)/{\cal B}(B_c^+\to J/ψπ^+) < 2.1\times 10^{-4}$ at $90\%$ confidence level. Additionally, an updated measurement of the ratio of the $B_c^+\toψ(2S)π^+$ and $B_c^+\to J/ψπ^+$ branching fractions is reported. The ratio ${\cal B}(B_c^+\toψ(2S)π^+)/{\cal B}(B_c^+\to J/ψπ^+)$ is measured to be $0.254\pm 0.018 \pm 0.003 \pm 0.005$, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the leptonic $J/ψ$ and $ψ(2S)$ decays. This measurement is the most precise to date and is consistent with previous LHCb results.

hep-ex↗

arXiv2024

Precision measurement of the branching fraction of \boldmath $J/ψ\rightarrow K^+K^-$ via $ψ(2S)\rightarrow π^+π^-J/ψ$

Using a sample of $448.1 \times 10^6$ $ψ(2S)$ events collected with the BESIII detector, we perform a study of the decay $J/ψ\rightarrow K^+K^-$ via $ψ(2S)\rightarrow π^+π^-J/ψ$. The branching fraction of $J/ψ\rightarrow K^+K^-$ is determined to be $\mathcal{B}_{K^+K^-}=(3.072\pm 0.023({\rm stat.})\pm 0.050({\rm syst.}))\times 10^{-4}$, which is consistent with previous measurements but with significantly improved precision.

hep-ex↗

arXiv2024

First study of antihyperon-nucleon scattering $\barΛp\rightarrow\barΛp$ and measurement of $Λp\rightarrowΛp$ cross section

Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the processes $Λp\rightarrowΛp$ and $\barΛp\rightarrow\barΛp$ are studied, where the $Λ/\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in $-0.9\leq\rm{cos}θ_{Λ/\barΛ}\leq0.9$ are measured to be $σ(Λp\rightarrowΛp)=(12.2\pm1.6_{\rm{stat}}\pm1.1_{\rm{sys}})$ mb and $σ(\barΛ p\rightarrow\barΛ p)=(17.5\pm2.1_{\rm{stat}}\pm1.6_{\rm{sys}})$ mb at the $Λ/\barΛ$ momentum of $1.074$ GeV/$c$ within a range of $\pm0.017$ GeV/$c$, where the $θ_{Λ/\barΛ}$ are the scattering angles of the $Λ/\barΛ$ in the $Λp/\barΛp$ rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for $Λp\rightarrowΛp$, and a strong forward peak for $\barΛp\rightarrow\barΛp$. We present an approach to extract the total elastic cross sections by extrapolation. The study of $\barΛp\rightarrow\barΛp$ represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction.

hep-ex↗

arXiv2024

Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at $\sqrt{s_{NN}}=5.02$ TeV with the LHCb detector

Flow harmonic coefficients, $v_n$, which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of $5.02$ TeV. The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features.

nucl-ex↗

arXiv2024

Observation of the $B_c^+ \to J/ψπ^+ π^0$ decay

The first observation of the $B_c^+ \to J/ψπ^+ π^0$ decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio of its branching fraction relative to the $B_c^+ \to J/ψπ^+$ channel is measured to be $$ \frac{ {\cal{B}}( B_c^+ \to J/ψπ^+π^0 ) } { {\cal{B}}( B_c^+ \to J/ψπ^+ ) } = 2.80 \pm 0.15 \pm 0.11 \pm 0.16 \,, $$ where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for $B^+ \to J/ψK^{*+}$ and $B^+ \to J/ψK^+$ decays, which are used to determine the $π^0$ detection efficiency. The $π^+π^0$ mass spectrum is found to be consistent with the dominance of an intermediate $ρ^+$ contribution in accordance with a model based on QCD factorisation.

hep-ex↗

arXiv2024

Search for the leptonic decays $D^{+}\to e^+ν_e$ and $D^{+}\to μ^+ν_μ$

We present the first search for the leptonic decays $D^{*+}\to e^+ν_e$ and $D^{*+}\to μ^+ν_μ$ by analyzing a data sample of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, corresponding to an integrated luminosity of 6.32~fb$^{-1}$. No significant signal is observed. The upper limits on the branching fractions for $D^{*+}\to e^+ν_e$ and $D^{*+}\to μ^+ν_μ$ are set to be $1.1 \times 10^{-5}$ and $4.3 \times 10^{-6}$ at 90\% confidence level, respectively.

hep-ex↗