Einstein Telescope (ET) is the European project for a gravitational-wave (GW) observatory of third-generation. In this paper we present a comprehensive discussion of its science objectives, providing state-of-the-art predictions for the capabilities of ET in both geometries currently under consideration, a single-site triangular configuration or two L-shaped detectors. We discuss the impact that ET will have on domains as broad and diverse as fundamental physics, cosmology, early Universe, astrophysics of compact objects, physics of matter in extreme conditions, and dynamics of stellar collapse. We discuss how the study of extreme astrophysical events will be enhanced by multi-messenger observations. We highlight the ET synergies with ground-based and space-borne GW observatories, including multi-band investigations of the same sources, improved parameter estimation, and complementary information on astrophysical or cosmological mechanisms obtained combining observations from different frequency bands. We present advancements in waveform modeling dedicated to third-generation observatories, along with open tools developed within the ET Collaboration for assessing the scientific potentials of different detector configurations. We finally discuss the data analysis challenges posed by third-generation observatories, which will enable access to large populations of sources and provide unprecedented precision.

Using the data samples of 102 million $\Upsilon(1S)$ and 158 million $\Upsilon(2S)$ events collected by the Belle detector, we search for a pentaquark state in the $pJ/\psi$ final state from $\Upsilon(1,2S)$ inclusive decays. Here, the charge-conjugate $\bar{p}J/\psi$ is included. We observe clear $pJ/\psi$ production in $\Upsilon(1,2S)$ decays and measure the branching fractions to be $\mathcal{B}[\Upsilon(1S) \to pJ/\psi + anything] = [4.27 \pm 0.16(stat.) \pm 0.20(syst.)] \times 10^{-5}$ and $\mathcal{B}[\Upsilon(2S) \to pJ/\psi + anything] = [3.59 \pm 0.14(stat.) \pm 0.16(syst.)] \times 10^{-5}$. We also measure the cross section of inclusive $pJ/\psi$ production in $e^+e^-$ annihilation to be $\sigma(e^+e^- \to pJ/\psi + anything) = [57.5 \pm 2.1 (stat.) \pm 2.5(syst.)]$~fb at $\sqrt{s} = 10.52~\hbox{GeV}$ using an 89.5~fb$^{-1}$ continuum data sample. There is no significant $P_c(4312)^+$, $P_c(4440)^+$ or $P_c(4457)^+$ signal found in the $pJ/\psi$ final states in $\Upsilon(1,2S)$ inclusive decays. We determine the upper limits of $\mathcal{B}[\Upsilon(1,2S)\to P_c^{+} + anything] \cdot \mathcal{B}(P_c^{+}\to pJ/\psi)$ to be at the $10^{-6}$ level.

We present a measurement of the ratio of partial branching fractions of the semileptonic inclusive decays, B-* Xul nu to B-* Xcl nu, where l 1/4 (e; mu), using the full Belle sample of 772 x 106 BB pairs collected at the Y(4S) resonance. The identification of inclusive B-* Xul nu decays is difficult due to the abundance of Cabibbo-Kobayashi-Maskawa-favored B-* Xcl nu events, which share a similar event topology. To minimize dependence on the modeling of these channels, a data-driven description of B-* Xcl nu is employed. The ratio is measured via a two-dimensional fit to the squared four-momentum transfer to the lepton pair, and the charged lepton energy in the B meson rest frame, where the latter must be larger than 1 GeV, covering approximately 86% and 78% of the B-* Xul nu and B-* Xcl nu phase space, respectively. We find oB(B-* Xul nu)/oB(B-* Xcl nu) 1/4 (1.99 +/- 0.17stat +/- 0.16syst) x 10-2, where the uncertainties are statistical and systematic, respectively. We extract jVubj/jVcbj using two theoretical calculations for the partial decay rate of B-* Xul nu, finding (jVubj/jVcbj)BLNP 1/4 (9.81 +/- 0.42stat +/- 0.38syst +/- 0.51or(B-*Xul nu) +/- 0.20or(B-*Xcl nu)) x 10-2 and (jVubj/jVcbj)GGOU 1/4 (10.06 +/- 0.43stat +/- 0.39syst +/- 0.23or(B-*Xul nu) +/- 0.20or(B-*Xcl nu)) x 10-2, where the third and fourth uncertainties are from the partial decay rates of B-* Xul nu and B-* Xcl nu, respectively. In addition, we report the partial branching fractions separately for charged and neutral B meson decays, and for electron and muon decay channels. We place a limit on isospin breaking in B-* Xul nu decays, and find no indication of lepton flavor universality violation in either the charmed or charmless mode. Furthermore, we unfold the B-* Xul nu and B-* Xcl nu yields and report the differential ratio in lepton energy and four-momentum transfer squared.

A series of data samples was collected with the Belle II detector at the SuperKEKB collider from March 2019 to June 2022. We determine the integrated luminosities of these data samples using three distinct methodologies involving Bhabha (e(+) e(-) -> e(+) e(-)(n gamma)), digamma (e(+) e(-) -> gamma gamma(n gamma)), and dimuon (e(+) e(-) -> mu(+) mu(-)(n gamma)) events. The total integrated luminosity obtained with Bhabha, digamma, and dimuon events is (426.88 +/- 0.03 +/- 2.61) fb(-1), (429.28 +/- 0.03 +/- 2.62) fb(-1), and (423.99 +/- 0.04 +/- 3.83) fb(-1), where the first uncertainties are statistical and the second are systematic. The resulting total integrated luminosity obtained from the combination of the three methods is (427.87 +/- 2.01) fb(-1).

We present measurements of the branching fractions of eight B^0→ D^(*)+ K^- K^(*)0_(S), B^-→ D^(*)0 K^- K^(*)0_(S) decay channels. The results are based on data from SuperKEKB electron-positron collisions at the Υ(4S) resonance collected with the Belle II detector, corresponding to an integrated luminosity of 362 fb^-1. The event yields are extracted from fits to the distributions of the difference between expected and observed B meson energy, and are efficiency-corrected as a function of m(K^-K^(*)0_(S)) and m(D^(*)K^(*)0_(S)) in order to avoid dependence on the decay model. These results include the first observation of B^0→ D^+K^-K_S^0, B^-→ D^*0K^-K_S^0, and B^0→ D^*+K^-K_S^0 decays and a significant improvement in the precision of the other channels compared to previous measurements. The helicity-angle distributions and the invariant mass distributions of the K^- K^(*)0_(S) systems are compatible with quasi-two-body decays via a resonant transition with spin-parity J^P=1^- for the K^-K_S^0 systems and J^P= 1^+ for the K^-K^*0 systems. We also present measurements of the branching fractions of four B^0→ D^(*)+ D_s^-, B^-→ D^(*)0 D_s^- decay channels with a precision compatible to the current world averages.

The full data set of the Daya Bay reactor neutrino experiment is used to probe the effect of the charged current non-standard interactions (CC-NSI) on neutrino oscillation experiments. Two different approaches are applied and constraints on the corresponding CC-NSI parameters are obtained with the neutrino flux taken from the Huber-Mueller model with a $5\%$ uncertainty. For the quantum mechanics-based approach (QM-NSI), the constraints on the CC-NSI parameters $\epsilon_{e\alpha}$ and $\epsilon_{e\alpha}^{s}$ are extracted with and without the assumption that the effects of the new physics are the same in the production and detection processes, respectively. The approach based on the weak effective field theory (WEFT-NSI) deals with four types of CC-NSI represented by the parameters $[\varepsilon_{X}]_{e\alpha}$. For both approaches, the results for the CC-NSI parameters are shown for cases with various fixed values of the CC-NSI and the Dirac CP-violating phases, and when they are allowed to vary freely. We find that constraints on the QM-NSI parameters $\epsilon_{e\alpha}$ and $\epsilon_{e\alpha}^{s}$ from the Daya Bay experiment alone can reach the order $\mathcal{O}(0.01)$ for the former and $\mathcal{O}(0.1)$ for the latter, while for WEFT-NSI parameters $[\varepsilon_{X}]_{e\alpha}$, we obtain $\mathcal{O}(0.1)$ for both cases.

Abstract The azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ s NN = 5.02 TeV down to transverse momentum (pT) of 0.5 GeV/c and 2 GeV/c, respectively, with ALICE. The results obtained in p-Pb collisions are based on a novel three-particle correlation technique. The azimuthal anisotropy coefficient v2 in high-multiplicity p-Pb collisions is positive, with a significance reaching 6.8σ at low pT, and its magnitude is smaller than in semicentral Pb-Pb collisions. In contrast to the measurements in Pb-Pb collisions, the v2 coefficient is also found independent of pT within uncertainties. Comparisons with the inclusive charged-particle v2 and with AMPT calculations are discussed. The predictions suggest that parton interactions play an important role in generating a non-zero jet-particle v2 in p-Pb collisions, even though they overestimate the reported measurement. These observations shed new insights on the understanding of the origin of the collective behaviour of jet particles in small systems such as p-Pb collisions, and provide significant stringent new constraints to models.

We report the first evidence for the h_b(2P) →Υ(1S)η transition with a significance of 3.5 standard deviations. The decay branching fraction is measured to be ℬ[h_b(2P) →Υ(1S)η]=(7.1  ^+3.7 _-3.2± 0.8)×10^-3, which is noticeably smaller than expected. We also set upper limits on π^0 transitions of ℬ[h_b(2P) →Υ(1S)π^0] < 1.8×10^-3, and ℬ[h_b(1P)→Υ(1S)π^0] < 1.8×10^-3, at the 90% confidence level. These results are obtained with a 131.4 fb^-1 data sample collected near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider.

We report measurements of the e+e− → BB , BB^∗ , and B^∗B^∗ cross sections at four energies, 10653, 10701, 10746 and 10805 MeV, using data collected by the Belle II experiment. We reconstruct one B meson in a large number of hadronic final states and use its momentum to identify the production process. In the first 2 – 5 MeV above B^∗B^∗ threshold, the e+e− → B^∗B^∗ cross section increases rapidly. This may indicate the presence of a pole close to the threshold.

Using the full data sample of 980 fb−1 collected with the Belle detector at the KEKB asymmetric energy electron-positron collider, we report the results of the first search for the rare semileptonic decays Ξc0→Ξ0ℓ+ℓ− (ℓ=e or μ). No significant signals are observed in the Ξ0ℓ+ℓ− invariant-mass distributions. Taking the decay Ξc0→Ξ−π+ as the normalization mode, we report 90% credibility upper limits on the branching fraction ratios B(Ξc0→Ξ0e+e−)/B(Ξc0→Ξ−π+)<6.7×10−3 and B(Ξc0→Ξ0μ+μ−)/B(Ξc0→Ξ−π+)<4.3×10−3 based on the phase-space assumption for signal decays. The 90% credibility upper limits on the absolute branching fractions of B(Ξc0→Ξ0e+e−) and B(Ξc0→Ξ0μ+μ−) are found to be 9.9×10−5 and 6.5×10−5, respectively. Published by the American Physical Society 2024

A Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a major upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to continuous readout, the complete overhaul of core detectors, as well as a new online event processing farm with a redesigned online-offline software framework. These improvements will allow to record Pb-Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature.

We have analyzed 121.4 fb-1 of data collected at the Gamma(5S) resonance by the Belle experiment using the KEKB asymmetric-energy e(+)e(-) collider to search for the decay B-s(0) -> J/psi pi(0). We observe no signal and report an upper limit on the branching fraction B(B-s(0) -> J/psi pi(0)) of 1.21 x 10(-5) at 90% confidence level. This result is the most stringent, improving the previous bound by 2 orders of magnitude.

We report a search for a heavy neutral lepton (HNL) that mixes predominantly with $\nu_\tau$. The search utilizes data collected with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. The data sample was collected at and just below the center-of-mass energies of the $\Upsilon(4S)$ and $\Upsilon(5S)$ resonances and has an integrated luminosity of $915~\textrm{fb}^{-1}$, corresponding to $(836\pm 12)\times 10^6$ $e^+e^\to\tau^+\tau^-$ events. We search for production of the HNL (denoted $N$) in the decay $\tau^-\to \pi^- N$ followed by its decay via $N \to \mu^+\mu^- \nu_\tau$. The search focuses on the parameter-space region in which the HNL is long lived, so that the $\mu^+\mu^-$ originate from a common vertex that is significantly displaced from the collision point of the KEKB beams. Consistent with the expected background yield, one event is observed in the data sample after application of all the event-selection criteria. We report limits on the mixing parameter of the HNL with the $\tau$ neutrino as a function of the HNL mass.

Abstract We report a search for the charged-lepton flavor violation in Υ(2S) → ℓ∓τ± (ℓ = e, μ) decays using a 25 fb−1 Υ(2S) sample collected by the Belle detector at the KEKB e+e− asymmetric-energy collider. We find no evidence for a signal and set upper limits on the branching fractions ($$ \mathcal{B} $$ B ) at 90% confidence level. We obtain the most stringent upper limits: $$ \mathcal{B} $$ B (Υ(2S) → μ∓τ±) < 0.23 × 10−6 and $$ \mathcal{B} $$ B (Υ(2S) → e∓τ±) < 1.12 × 10−6.

We search for excited charmed baryons in the Λ_c^+η system using a data sample corresponding to an integrated luminosity of 980 fb^-1. The data were collected by the Belle detector at the KEKB e^+e^- asymmetric-energy collider. No significant signals are found in the Λ_c^+η mass spectrum, including the known Λ_c(2880)^+ and Λ_c(2940)^+. Clear Λ_c(2880)^+ and Λ_c(2940)^+ signals are observed in the pD^0 mass spectrum. We set upper limits at 90% credibility level on ratios of branching fractions of Λ_c(2880)^+ and Λ_c(2940)^+ decaying to Λ_c^+η relative to Σ_c(2455)π of <0.13 for the Λ_c(2880)^+ and <1.11 for the Λ_c(2940)^+. We measure ratios of branching fractions of Λ_c(2880)^+ and Λ_c(2940)^+ decaying to pD^0 relative to Σ_c(2455)π of 0.75 ± 0.03(stat.) ± 0.07(syst.) for the Λ_c(2880)^+ and 3.59 ± 0.21(stat.) ± 0.56(syst.) for the Λ_c(2940)^+.

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λc+ baryons, z∥ch, in hadronic collisions. The results are obtained in proton-proton (pp) collisions at s=13 TeV at the LHC, with Λc+ baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of 3≤pTΛc+<15 GeV/c and 7≤pTjet ch<15 GeV/c, respectively. The z∥ch distribution is compared to a measurement of D0-tagged charged jets in pp collisions as well as to 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as predicted by hadronization models which include color correlations beyond leading-color in the string formation. © 2024 CERN, for the ALICE Collaboration 2024 CERN

Collective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the CERN Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle multiplicities comparable to peripheral Pb-Pb collisions. One of the possible signatures of collective behavior is the decrease of femtoscopic radii extracted from pion and kaon pairs emitted from highmultiplicity collisions with increasing pair transverse momentum. This decrease can be described in terms of an approximate transverse mass scaling. In the present work, femtoscopic analyses are carried out by the ALICE Collaboration on charged pion and kaon pairs produced in pp collisions at root s = 13 TeV from the LHC to study possible collectivity in pp collisions. The event-shape analysis method based on transverse sphericity is used to select for spherical versus jetlike events, and the effects of this selection on the femtoscopic radii for both charged pion and kaon pairs are studied. This is the first time this selection method has been applied to charged kaon pairs. An approximate transverse-mass scaling of the radii is found in all multiplicity ranges studied when the difference in the Lorentz boost for pions and kaons is taken into account. This observation does not support the hypothesis of collective expansion of hot and dense matter that should only occur in high-multiplicity events. A possible alternate explanation of the present results is based on a scenario of common emission conditions for pions and kaons in pp collisions for the multiplicity ranges studied.

We report the results of the first search for B^- decays to the Ξ̅_c^0Λ̅_c^- final state using 711 fb^-1 of data collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider. The results are interpreted in terms of both direct baryon-number-violating B^- decay and Ξ_c^0-Ξ̅_c^0 oscillations which follow the Standard Model decay B^- →Ξ_c^0Λ̅_c^-. We observe no evidence for baryon number violation and set the 95% confidence-level upper limits on the ratio of baryon-number-violating and Standard Model branching fractions ℬ(B^- →Ξ̅_c^0Λ̅_c^-)/ℬ(B^- →Ξ_c^0Λ̅_c^-) to be < 2.7% and on the Ξ_c^0 - Ξ̅_c^0 oscillation angular frequency ω to be < 0.76ps^-1 (equivalent to τ_ mix > 1.3 ps).

We present a study of Ξ_c^0→Ξ^0π^0 , Ξ_c^0→Ξ^0η , and Ξ_c^0→Ξ^0η^' decays using the Belle and Belle II data samples, which have integrated luminosities of 980 fb−1 and 426 fb−1, respectively. We measure the following relative branching fractions [ ℬ(Ξ_c^0→Ξ^0π^0)/ℬ(Ξ_c^0→Ξ^-π^+)=0.48± 0.02(stat)± 0.03(syst),; ℬ(Ξ_c^0→Ξ^0η)/ℬ(Ξ_c^0→Ξ^-π^+)=0.11± 0.01(stat)± 0.01(syst),; ℬ(Ξ_c^0→Ξ^0η^')/ℬ(Ξ_c^0→Ξ^-π^+)=0.08± 0.02(stat)± 0.01(syst) ] for the first time, where the uncertainties are statistical (stat) and systematic (syst). By multiplying by the branching fraction of the normalization mode, ℬ(Ξ_c^0→Ξ^-π^+) , we obtain the following absolute branching fraction results [ ℬ(Ξ_c^0→Ξ^0π^0)=(6.9± 0.3(stat)± 0.5(syst)± 1.3(norm))×10^-3,; ℬ(Ξ_c^0→Ξ^0η)=(1.6± 0.2(stat)± 0.2(syst)± 0.3(norm))×10^-3,; ℬ(_c^0→Ξ^0η^')=(1.2± 0.3(stat)± 0.1(syst)± 0.2(norm))×10^-3, ] where the third uncertainties are from ℬ(Ξ_c^0→Ξ^-π^+) . The asymmetry parameter for Ξ_c^0→Ξ^0π^0 is measured to be α(Ξ_c^0→Ξ^0π^0)=-0.90± 0.15(stat)± 0.23(syst) .

Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at √(s) = 13 TeV and p–Pb collisions at √(s_NN) = 5.02 TeV. The correlation functions are measured as a function of relative azimuthal angle ∆φ and pseudorapidity separation ∆η for pairs of primary charged particles within the pseudorapidity interval |η| < 0.9 and the transverse-momentum interval 1 < pT < 4 GeV/c. Flow coefficients are extracted for the long-range correlations (1.6 < |∆η| < 1.8) in various high-multiplicity event classes using the low-multiplicity template fit method. The method is used to subtract the enhanced yield of away-side jet fragments in high-multiplicity events. These results show decreasing flow signals toward lower multiplicity events. Furthermore, the flow coefficients for events with hard probes, such as jets or leading particles, do not exhibit any significant changes compared to those obtained from high-multiplicity events without any specific event selection criteria. The results are compared with hydrodynamic-model calculations, and it is found that a better understanding of the initial conditions is necessary to describe the results, particularly for low-multiplicity events.