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P. Adlarson

Publications and source records attributed to P. Adlarson.

At least 19 recordsLinked to original sources
arXiv2026

Measurement of Born Cross Sections for $e^+e^- \to K^+Ξ^0\barΣ^-$ at $\sqrt{s} = 3.51-4.95$ GeV and Observation of $ψ(3770) \to K^+Ξ^0\barΣ^-$

Using 44.55 fb$^{-1}$ of $e^+e^-$ collision data collected by the BESIII detector at the BEPCII collider, we report the first measurement of the Born cross sections for the $e^+e^- \to K^+Ξ^0\barΣ^-$ reaction at fifty-six center-of-mass energies between 3.51 and 4.95~GeV. A fit to the dressed cross sections reveals the first observation of the $ψ(3770) \to K^+Ξ^0\barΣ^-$ process, with a statistical significance of 6.0$σ$ including systematic uncertainties. This result represents the first observation of charmless three-body baryonic decay of a vector charmonium state above the open-charm threshold. No significant signals for other charmonium(-like) states i.e., $ψ(4040)$, $ψ(4160)$, $Y(4230)$, $Y(4360)$, $ψ(4415)$, $Y(4500)$, $Y(4660)$ or $Y(4710)$ are observed, and the upper limits for the product of the branching fraction and the electronic partial width at the 90% confidence level for each assumed charmonium(-like) state are provided. Additionally, the ratios of Born cross sections between this work and the previous measurements of $e^+e^- \to K^{0}_{S}\barΞ^{-}Σ^-$ and $K^-\barΞ^+\barΣ^0$ are provided, which can be used to validate theoretical predictions related to isospin symmetry.

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arXiv2026

Amplitude analysis of the charmed baryon decay Lambda_c+ to p K_S^0 pi0

Using $e^+e^-$ annihilation data corresponding to an integrated luminosity of 4.5 fb$^{-1}$ collected with the BESIII detector at center-of-mass energies between 4.600 and 4.699 GeV, the first amplitude analysis of the charmed baryon decay $Λ_c^+ \to p K_S^0 π^0$ is performed. The processes $Λ_c^+ \to p \bar{K}^{*}(892)^0$, $Λ_c^+ \to Δ(1600)^+ K_S^0$, and $Λ_c^+ \to N(1710)^+ K_S^0$ are identified with statistical significances of $12.8σ$, $14.5σ$, and $6.2σ$, respectively. The mass and width of $Δ(1600)^+$ are measured to be $(1520.4 \pm 8.8 \pm 37.7)~\text{MeV}$ and $(199.4 \pm 26.4 \pm 39.9)~\text{MeV}$, respectively. The mass and width of $N(1710)^+$ are measured to be $(1719.7 \pm 9.4 \pm 9.1)~\text{MeV}$ and $(72.0 \pm 18.0 \pm 15.0)~\text{MeV}$, respectively. The branching fractions of these processes are determined to be $\mathcal{B}[Λ_c^+ \rightarrow Δ(1600)^+ (\rightarrow p π^0) K_S^0] = (8.10 \pm 0.80 \pm 5.57) \times 10^{-3}$, $\mathcal{B}[Λ_c^+ \rightarrow N(1710)^+ (\rightarrow p π^0) K_S^0] = (1.58 \pm 0.48 \pm 0.77) \times 10^{-3}$, and $\mathcal{B}[Λ_c^+ \rightarrow p \bar{K}^{*}(892)^0 (\rightarrow K_S^0 π^0)] = (2.63 \pm 0.47 \pm 0.29) \times 10^{-3}$, where the first uncertainties are statistical and the second systematic.

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arXiv2026

Study of $ϕ\to K\bar{K}$ in the amplitude analysis of $D^{+}\to K_{S}^{0}K_{L}^{0}π^{+}$

We present the first amplitude analysis and branching fraction measurement of $D^{+} \rightarrow K_{S}^{0}K_{L}^{0}π^{+}$ decay. The analysis uses a dataset corresponding to an integrated luminosity of 20.3~$\rm fb^{-1}$, which was recorded at a center-of-mass energy 3.773~GeV by the BESIII detector. The measured branching fraction is $\mathcal{B}(D^{+} \rightarrow K_{S}^{0}K_{L}^{0}π^{+})=(5.780\pm0.085\pm 0.052)\times10^{-3}$, where the first uncertainty is statistical and the second is systematic. Using the known value of ${\cal B}(D^+ \to ϕπ^+,\,ϕ\to K^+K^-)$, we determine the relative branching fraction between $ϕ\to K_{S}^0K_{L}^0$ and $ϕ\to K^+K^-$ to be $\mathcal{B}(D^{+} \to ϕπ^{+}, ϕ\to K_{S}^0K_{L}^0)/\mathcal{B}(D^{+} \to ϕπ^{+}, ϕ\to K^+K^-)= 0.628\pm0.022\pm 0.015\pm0.017$, where the third uncertainty is related to $\mathcal{B}(D^{+} \to ϕπ^{+}, ϕ\to K^+K^-)$. This result is significantly lower than the previous world average and is consistent with the isospin expectation for the $ϕ$ meson's coupling to charged and neutral kaon pairs.

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arXiv2026

Precise Measurement of the Inclusive Cross Sections of Open-Charm Mesons at Energies from 3.80 to 4.95 GeV

Using $e^+e^-$ collision data collected by the BESIII detector at center-of-mass energies from $3.80$ to $4.95~\text{GeV}$, the inclusive production cross sections of open-charm mesons, $σ(e^{+}e^{-}\to D^{0}/D^{+}/D_{s}^{+}+X)$, are measured by tagging a $D^0$, $D^+$, or $D_s^+$ meson, where $X$ denotes any accompanying particles. Open-charm production dominates the total hadronic yield above threshold. Therefore these measurements provide a vital reference for understanding hadron production and for validating global $R$ value results. The results offer crucial inputs for investigating heavier charmonia and exotic states coupled to open-charm final states, while serving as a benchmark for comparison with the sum of measured exclusive channels. This comparison directly evaluates the completeness of current exclusive datasets and clarifies the underlying hadronization mechanisms in the open-charm region.

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arXiv2026

Search for $e^{+}e^{-} \to π^0 K^+K^-J/ψ$ at $\sqrt{s}= 4.26 \sim$ 4.95 GeV

Using $e^+e^-$ collision data collected with the BESIII detector at 27 center-of-mass energies between 4.26 and 4.95 GeV corresponding to a total integrated luminosity of $13.0~\text{fb}^{-1}$, we report the first search for the process $e^{+}e^{-} \to π^0 K^+K^-J/ψ$. We additionally probe the cross section spectra for potential charmonium-like vector states and invariant mass distributions for intermediate $Z_c/Z_{cs}$ state signals, and find no resonant structures consistent with these exotic candidates. Given the absence of observed resonant signals, upper limits at the 90\% confidence level are determined for the Born cross sections, along with their best-fit values, as well as for the production of the intermediate states.

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arXiv2026

Improved measurement of $ψ(3686)\to π^+π^- η$

Using a sample of $(2712.4 \pm 14.3) \times 10^6$ $ψ(3686)$ events collected with the BESIII detector, we perform a partial wave analysis of the decay $ψ(3686)\toπ^{+}π^{-}η$ with the $π^{+}π^{-}$ invariant mass in the $ρ(770)^0$ mass region, [0.3, 2.2] $\mathrm{GeV}/c^2$. The cross section line-shape around the $ψ(3686)$ resonance is measured using energy-scan data sets, enabling the estimation of continuum contribution and its interference with the $ψ(3686)$ resonance. The branching fraction of $ψ(3686)\toρ(770)^0η$ is determined to be $(1.34 \pm 0.03\pm0.13) \times 10^{-5}$. The $ψ(3686)\to a_{2}(1320)^{\pm}π^{\mp}$ decay is observed for the first time with a significance of $35.7σ$, and its partial branching fraction is measured to be $(2.13 \pm 0.05\pm0.32) \times 10^{-5}$. The $η$-$η^{\prime}$ pseudoscalar mixing angle $θ_P$ is then found to be $(-11.2 \pm 1.6\pm3.6)^\circ$ or $(-19.4\pm 3.1\pm5.7)^\circ$, where the first uncertainty is statistical and the second systematic.

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arXiv2026

Precision measurement of the $J/ψ\toμ^+μ^-μ^+μ^-$ branching fraction and search for a new gauge boson $Z^{\prime}$ at BESIII

We present a precision measurement of the branching fraction of the rare decay $J/ψ\toμ^+μ^-μ^+μ^-$, and a search for a new gauge boson $Z^{\prime}$ that couples only to the second and third lepton generations, using a data sample of $(8998 \pm 39) \times 10^6$ $J/ψ$ events collected by the BESIII detector. The branching fraction of the $J/ψ\toμ^+μ^-μ^+μ^-$ decay is measured to be $B(J/ψ\toμ^+μ^-μ^+μ^-)=[0.91\pm0.04~{\rm (stat.)}\pm0.07~{\rm (syst.)}]\times 10^{-6}$, representing the most precise measurement to date and consistent with the theoretical prediction within one standard deviation. Additionally, we search for $CP$ asymmetry in the $J/ψ\toμ^+μ^-μ^+μ^-$ decay and determine the T-odd observable to be $A_T = [0.05\pm 0.04~{\rm (stat.)}\pm0.01~{\rm (syst.)}]$, which is consistent with $CP$ conservation. In the search for $J/ψ\to Z^{\prime}μ^+μ^-$ via $Z^{\prime}\toμ^+μ^-$, no significant $Z^{\prime}$ signal is observed in the $μ^+μ^-$ invariant mass region of $(0.212,~2.6)$~GeV$/c^2$, and we set upper limits on the ${\rm U}(1)_{L_μ-L_τ}$ model coupling constant $g^{\prime}$ ranging from 0.001 to 0.294 at the 90\% confidence level, which is comparable to the upper limits set by Belle II for $Z^{\prime}$ masses below $0.7$~GeV$/c^2$.

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arXiv2026

Observation of $χ_{c1,2}\to p K^- K^- \bar Ξ^{+} +c.c.$ and search for $χ_{c0}\to p K^- K^- \bar Ξ^{+} +c.c.$

By analyzing $(2.712\pm0.014)\times10^9$ $ψ(3686)$ events collected by the BESIII detector, we report the first experimental study of the decays $χ_{cJ}\to p K^- K^- \bar Ξ^{+}+c.c.~(J=0,1,2)$. The decays $χ_{c1}\to p K^- K^- \bar Ξ^{+}+c.c.$ and $χ_{c2}\to p K^- K^- \bar Ξ^{+}+c.c.$ are observed for the first time with significances of $9.0σ$ each, and their branching fractions are determined to be $\mathcal{B}_{χ_{c1}\to p K^- K^- \bar Ξ^{+}+c.c.} =(9.6^{+2.2}_{-2.0}\pm0.8)\times10^{-6}$, and $\mathcal{B}_{χ_{c2}\to p K^- K^- \bar Ξ^{+}+c.c.} =(7.5^{+1.8}_{-1.5}\pm0.5)\times10^{-6}$, where the first and second uncertainties are statistical and systematic, respectively. No significant signal is observed for $χ_{c0}\to p K^- K^- \bar Ξ^{+}+c.c.$, and an upper limit on its branching fraction of $12.7\times10^{-6}$ is established at the 90\% confidence level.

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arXiv2026

First measurement of $ψ(3686)\to\bar{p} K^{+} Σ^{*}(1385)^{0} + c.c.$ and $ψ(3686)\to\bar{p} K^{*}(892)^{0} Σ^{+} + c.c.$

Based on a sample of $(2712.4 \pm 14.3) \times 10^6$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, we report the first observation of the decays $ψ(3686)\to\bar{p} K^{+} Σ^{*}(1385)^{0}+c.c.$ and $ψ(3686)\to\bar{p} K^{*}(892)^{0} Σ^{+} + c.c.$. The corresponding branching fractions are determined to be $\mathcal{B}(ψ(3686)\to\bar{p}K^+Σ^{*}(1385)^{0}+c.c.)=(3.94\pm0.15_{\text{stat.}}\pm0.24_{\text{syst.}})\times10^{-5}$ and $\mathcal{B}(ψ(3686)\to\bar{p}K^{*}(892)^{0}Σ^++c.c.)=(4.93\pm0.14_{\text{stat.}}\pm0.30_{\text{syst.}})\times10^{-5}$. Furthermore, we search for the hidden-strange pentaquark candidates $N_{x}(1875)$ and $N_{x}(2100)$ in the invariant mass spectra of $K^{+} Σ^{*}(1385)^{0}$ and $K^{*}(892)^{0} Σ^{+}$, respectively. No significant signals are observed and the upper limits on the branching fractions at the 90% confidence level are $\mathcal{B}(ψ(3686)\to\bar{p}N_{x}(1875)\to\bar{p}K^+Σ^{*}(1385)^{0})<1.58\times10^{-6}$ and $\mathcal{B}(ψ(3686)\to\bar{p}N_{x}(2100)\to\bar{p}K^{*}(892)^{0}Σ^+)<3.09\times10^{-7}$.

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arXiv2026

Observation of the $T_{c\bar{c}1}(4430)^-$ state in $B^0\to D^{*-}D^0K^+$ decays

A study of resonant structures in $B^0 \to D^{*-}D^0K^+$ decays is presented. The analysis uses proton-proton collision data collected by the LHCb experiment at center-of-mass energies of $\sqrt{s} = 7$, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb$^{-1}$. The analysis demonstrates that the existing known excited $D_s^+$ resonances in the $D^0K^+$ spectrum are insufficient to describe the data. The inclusion of the tetraquark state $T_{c\bar{c}1}(4430)^-$ improves the description of the data with a statistical significance exceeding $5σ$. This corresponds to the first observation of the $T_{c\bar{c}1}(4430)^- \to D^{*-} D^0$ decay. The measured properties of the $T_{c\bar{c}1}(4430)^-$ state are consistent with those previously measured in its decay to the $ψ(2S)π^-$ final state.

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arXiv2026

Stringent limits on $C\!PT$- and Lorentz-invariance violation from $B_s^0$ meson decays

Tests of fundamental symmetries, such as $C\!PT$ and Lorentz invariance, provide sensitive probes of physics beyond the standard quantum-field-theory framework. Possible violations of these symmetries are investigated through interference effects in decays of $B_s^0$ mesons to $D_s^-π^{+}$ states. The analysis uses proton-proton collision data collected with the LHCb detector in 2015-2018 at a centre-of-mass energy of $13~\mathrm{TeV}$, corresponding to an integrated luminosity of $6~\mathrm{fb}^{-1}$. The results are interpreted within the Standard Model Extension framework, yielding sensitivities to the Lorentz-violating parameter $Δa_μ$ at the ${\cal O}(10^{-14})\,\mathrm{GeV}$ level. Without assuming Lorentz-invariance violation, the $C\!PT$-violating parameter $z$ in the $B_s^0$ system is measured to be $\mathcal{R}e(z) = 0.018 \pm 0.016 \pm 0.003$ and $\mathcal{I}m(z) = 0.003 \pm 0.004 \pm 0.002$, where the first uncertainties are statistical and the second systematic. These results represent the most precise constraints on $C\!PT$ violation in the $B_s^0$ system.

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arXiv2026

Search for the rare decay $η^{\prime}\to 3γ$

Using a data sample of $(10087 \pm 44) \times 10^{6} J/ψ$ events collected with the BESIII detector, we search for the rare decay $η^{\prime}\to 3γ$ via the process $J/ψ\toγη^{\prime}$. No significant signal is observed and an upper limit on the branching fraction of $η^{\prime}\to 3γ$ is set at $\mathcal{B}(η^{\prime}\to 3γ) < 2.25\times 10^{-5}$ at the 90\% confidence level. This result improves the previous upper limit by more than a factor of four.

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arXiv2026

Measurement of Born Cross Sections for $e^+e^-\toΣ^-\barΣ^+$ at $\sqrt{s}=3.51-4.95$ GeV and Observation of $ψ(3770)\toΣ^-\barΣ^+$

Using $e^+e^-$ collision data corresponding to an integrated luminosity of 44 fb$^{-1}$ collected with the BESIII detector at the BEPCII collider, we report the first measurement of Born cross sections and effective form factors for $e^+e^-\toΣ^-\barΣ^+$ at centre-of-mass energies between 3.51 and 4.95 GeV. With a fit to the $\sqrt{s}$-dependent dressed cross sections, the decay $ψ(3770)\toΣ^-\barΣ^+$ is observed for the first time with a significance of 5.5$σ$, including systematic uncertainties. Upper limits at the 90\% confidence level on the product of the branching fraction and the electronic partial width are provided for other possible charmonium(-like) states. The ratios of Born cross sections for the $Σ$ isospin-triplet states are determined and can be used to test the vector-meson-dominance model.

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arXiv2026

First determination of the full spin density matrix in $ψ(3686)\toΛ\barΛ$

Using $(448.1\pm2.9)\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector, we present the first complete determination of the spin density matrix in $ψ(3686)\toΛ\barΛ$. This provides a unified framework to study both the production dynamics and the quantum correlations of the $Λ\barΛ$ system. From a five-dimensional joint angular analysis, we determine $α_ψ=0.82\pm0.02_{\mathrm{stat.}}\pm0.01_{\mathrm{syst.}}$ and $ΔΦ=(20.6\pm3.6_{\mathrm{stat.}}\pm0.6_{\mathrm{syst.}})^{\circ}$. The non-zero phase implies a transverse polarization of $Λ$, with a maximum value of $P_{y} = 0.074 \pm 0.013_{\mathrm{stat.}} \pm 0.003_{\mathrm{syst.}}$ and a significance of 6.3$σ$. The same framework also gives access to the spin correlations of the baryon pair and enables tests of quantum nonclassicality. The average of the Bell nonlocality measure is determined to be $\bar{m}_{12} = 1.266 \pm 0.078_{\mathrm{stat.}} \pm 0.049_{\mathrm{syst.}}$, yielding a violation of the Clauser-Horne-Shimony-Holt inequality with a significance of 3.7$σ$. These results establish $ψ(3686)\toΛ\barΛ$ as a unique laboratory for unified studies of hadron production dynamics and quantum entanglement in a system of massive baryons.

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arXiv2026

Measurement of the relative phase between the strong and electromagnetic amplitudes in $\boldsymbol{J/ψ\to Σ^{+} \barΣ^{-}}$

Using 284 pb$^{-1}$ of $e^{+}e^{-}$ collision data collected with the BESIII detector at center-of-mass energies between 3.00 and 3.12 GeV, the relative phase between the strong and electromagnetic interaction amplitudes in the process $J/ψ\to Σ^+ \barΣ^-$ is determined. The relative phase is measured to be $(107.9 \pm 24.9)^{\circ}$ or $(-107.6 \pm 24.3)^{\circ}$, where the uncertainty includes both statistical and systematic sources. This is the first experimental determination of the strong-electromagnetic phase difference in $J/ψ$ decays to a hyperon-antihyperon pair. The branching fraction $\mathcal{B}_{J/ψ\to Σ^+ \barΣ^-}$ is measured to be $(1.14 \pm 0.04)\times 10^{-3}$ for the positive phase solution or $(1.19 \pm 0.04) \times 10^{-3}$ for the negative phase solution. These results provide important input for testing perturbative QCD predictions and studies of SU(3) flavor symmetry.

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arXiv2026

Observation of an Altered $a_{0}(980)$ Line shape in $D^{+} \rightarrow π^{+}ηη$

Using $20.3~{\rm fb}^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector at $\sqrt{s}=3.773~{\rm GeV}$, we perform the first amplitude analysis of the decay $D^+\toπ^+ηη$. The intermediate process $D^+\to a_0(980)^+η$, $a_0(980)^+\toπ^+η$, is observed as the only significant component in the amplitude analysis, and its branching fraction is measured to be $(3.67\pm0.12_{\rm stat}\pm0.06_{\rm syst})\times10^{-3}$. The $π^+η$ mass spectrum associated with $a_0(980)^+η$ production exhibits a line shape that differs substantially from those observed in $D_{(s)}\to a_0(980)π$ and $D^0\to a_0(980)^-e^+ν_e$ decays. We examine several conventional descriptions of the $a_0(980)$ amplitude, including Flatté, dispersively modified Flatté, $T$-matrix, and $K$-matrix parameterizations. With reference $a_0(980)$ parameters, neither these models nor their extensions including additional small resonant or non-resonant amplitudes reproduce the observed line shape satisfactorily. When the $a_0(980)$ parameters are allowed to float, satisfactory fits can be obtained, but the pole mass is driven well above the $K\bar K$ threshold, inconsistent with the near-threshold character of the $a_0(980)$. The results reveal a tension between fit quality and the physical pole position in conventional direct-production amplitude models.

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arXiv2026

First Observation of the Radiative Decay $D^0 \to γω$

We report the first observation of the radiative charm decay $D^0 \to γω$ with a significance of $6.0σ$. The analysis uses 20.3\,$\rm{fb}^{-1}$ of $e^+e^-$ collision data collected by the BESIII detector at a center-of-mass energy of 3.773\,GeV, and employs a deep learning strategy based on the Particle Transformer architecture. The absolute branching fraction of $\mathcal{B}(D^0\toγω)=(2.12\pm 0.40_{\rm stat}\pm 0.25_{\rm syst})\times 10^{-5}$ confirms the dominance of long-distance hadronic dynamics in radiative charm decays and provides a valuable benchmark for testing non-perturbative QCD calculations of $D \to γV$ transitions.

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arXiv2026

Observation of the ${Ξ_b^-\to Ξ^-μ^+μ^-}$ and study of the ${Ξ_b^-\toΞ^-ψ(2S)}$ decays

The rare decay ${Ξ_b^-\toΞ^-μ^+μ^-}$ is observed for the first time using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of $7$, $8$ and~$13~\text{TeV}$, corresponding to integrated luminosities of $1$, $2$ and $6~\text{fb}^{-1}$, respectively. Its branching fraction is reported in intervals of the dimuon invariant mass squared. The integrated value of ${\cal{B}}(Ξ_b^-\toΞ^-μ^+μ^-)$ is measured to be ${ (118 \pm 24 \pm 7 \pm 38 ) \times 10^{-8}}$, where the first uncertainty is statistical, the second is systematic and the third uncertainty arises from the normalisation branching fraction ${\cal{B}}(Ξ_b^-\toΞ^-J/ψ)$, whose uncertainty is dominated by SU(3)-breaking effects. In addition, the ratio of the branching fractions of the ${Ξ_b^-\toΞ^-ψ(2S)}$ and the ${Ξ_b^-\toΞ^-J/ψ}$ decays is measured to be ${ 0.491 \pm 0.041 \pm 0.019 }$.

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