Search

Measurements of the differential production cross-sections of prompt and non-prompt J / ψ and ψ (2 S) mesons with transverse momenta between 8 and 360 GeV and rapidity in the range | y | < 2 are reported. Furthermore, measurements of the non-prompt fractions of J / ψ and ψ (2 S) , and the prompt and non-prompt ψ (2 S) -to- J / ψ production ratios, are presented. The analysis is performed using 140 fb - 1 of s = 13 TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018. [ABSTRACT FROM AUTHOR]

The elliptic flow (v 2) of D 0 mesons from beauty-hadron decays (non-prompt D 0) was measured in midcentral (30–50%) Pb–Pb collisions at a centre-of-mass energy per nucleon pair s NN = 5.02 TeV with the ALICE detector at the LHC. The D 0 mesons were reconstructed at midrapidity (| y | < 0.8) from their hadronic decay D 0 → K - π + , in the transverse momentum interval 2 < p T < 12 GeV/c. The result indicates a positive v 2 for non-prompt D 0 mesons with a significance of 2.7 σ . The non-prompt D 0 -meson v 2 is lower than that of prompt non-strange D mesons with 3.2 σ significance in 2 < p T < 8 GeV / c , and compatible with the v 2 of beauty-decay electrons. Theoretical calculations of beauty-quark transport in a hydrodynamically expanding medium describe the measurement within uncertainties. [ABSTRACT FROM AUTHOR]

The very rare D ∗ (2007) 0 → μ + μ - decay is searched for by analysing B - → π - μ + μ - decays. The analysis uses a sample of beauty mesons produced in proton–proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 \,fb - 1 . The signal signature corresponds to simultaneous peaks in the μ + μ - and π - μ + μ - invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at B (D ∗ (2007) 0 → μ + μ -) < 2.6 × 10 - 8 at 90 % confidence level. This is the first limit on the branching fraction of D ∗ (2007) 0 → μ + μ - decays and the most stringent limit on D ∗ (2007) 0 decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays. [ABSTRACT FROM AUTHOR]

We report on the results of the first search for the production of axion-like particles (ALPs) via Primakoff production on nuclear targets, γ A → a A , in the "SRC-CT" experiment using the GlueX detector at Jefferson Lab. This search uses an integrated luminosity of 100 pb ⋅ − 1 nucleon on a 12C target with a real photon beam of energies 6 < E γ < 10.8 GeV, and explores the mass region of 200 < m a < 450 MeV via the decay a → γ γ. This mass range is between the π 0 and η meson masses, which enables the use of the measured η meson production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the effective photon coupling scale of O (1 TeV − 1). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant background the in GlueX spectrometer, which we treat by using data on 4He to estimate and subtract it. We comment on how this search can be improved in a future higher-statistics dedicated measurement. [ABSTRACT FROM AUTHOR]

We present a search for the charged lepton-flavor-violating decays ϒ(1S) →ℓ±ℓ′∓ and radiative charged lepton-flavour-violating decays ϒ(1S) → γℓ±ℓ′∓ [ℓ,ℓ′ = e, μ, τ] using the 158 million ϒ(2S) sample collected by the Belle detector at the KEKB collider. This search uses ϒ(1S) mesons produced in ϒ(2S) → π+π− ϒ(1S) transitions. We do not find any significant signal, so we provide upper limits on the branching fractions at the 90% confidence level. [ABSTRACT FROM AUTHOR]

Arrays of superconducting transition-edge sensor (TES) microcalorimeters are attractive for some X-ray experiments where the combination of higher collection efficiency than crystal spectrometers and much better energy resolution than semiconductor detectors is enabling. For hard X-ray (>2 keV) applications, a TES is often integrated with an extra absorber to extend its dynamic range, quantum efficiency and collecting area. For >100 keV applications, millimeter size absorbers have been manually attached to TES pixels after fabrication. At lower energies, the absorber size needs to be much smaller, because a large heat capacity degrades energy resolution. In that case, the absorber is directly electroplated or evaporated on the TES during the fabrication process. In this work, we present TES microcalorimeters optimized for the intermediate hard X-ray energy region (20 keV ∼ 100 keV) that have thick absorbers directly deposited during the TES fabrication process. This microcalorimeter is designed to measure high-resolution muonic atom transition X-ray spectra as a method to study quantum electrodynamics (QED) effects. The absorber is comprised of evaporated gold and electroplated bismuth layers and is designed to optimize dynamic range, collecting efficiency, and energy resolution in the 20 keV to 45 keV energy range. A prototype with pure gold absorbers has been fabricated and characterized, in order to obtain a first experimental reference in the detector development process. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the spectra of the prospective hidden-bottom and -charm hexaquark states with quantum numbers J PC = 0 + + , 0 - + , 1 + + and 1 - - in the framework of QCD sum rules. By constructing appropriate interpreting currents, the QCD sum rules analyses are performed up to dimension 12 of the condensates. Results indicate that there exist two possible baryonium states in b-quark sector with masses 11.84 ± 0.22 GeV and 11.72 ± 0.26 GeV for 0 + + and 1 - - , respectively. The corresponding hidden-charm partners are found lying respectively at 5.19 ± 0.24 GeV and 4.78 ± 0.23 GeV. Note that these baryonium states are all above the dibaryon thresholds, which enables their dominant decay modes could be measured at BESIII, BELLEII, and LHCb detectors. [ABSTRACT FROM AUTHOR]

We plan to conduct an experimental search for η'-mesic nuclei in order to investigate in-medium properties of the η' meson. A 2.5 GeV proton beam is employed to produce η'-mesic 11C nuclei with the 12C(p,d)η' 11C reaction. Simultaneous measurements of the forward ejected deuterons and decay protons from η'-mesic nuclei will allow us to achieve high experimental sensitivity. The experiment will be performed at GSI by making full use of the fragment separator FRS and the WASA detector system. The plan of this proposed experiment is described. [ABSTRACT FROM AUTHOR]

The iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) will be used to measure neutrino mass hierarchy. The magnet in the ICAL detector will be used to distinguish the \mu ^- and \mu ^+ events induced by \nu \mu and anti- \nu \mu , respectively. Due to the importance of the magnet in ICAL, an electromagnetic simulation has been carried out to study the $B$ -field distribution in iron using various designs. The simulation shows better uniformity in the portion of the iron layer between the coils, which is bounded by regions that have lesser field strength as we move to the periphery of the iron layer. The ICAL magnet was configured to have a tiling structure that gave the minimum reluctance path, while keeping a reasonably uniform field pattern. This translates into less ampere-turns needed for generation of the required magnetic field. At low ampere-turns, a larger fractional area with $|B|\ge 1$ T can be obtained using a soft magnetic material. A study of the effect of the magnetic field on muon trajectories has been carried out using GEANT4. For muons up to 20 GeV, the energy resolution improves as the magnetic field increases from 1.1 to 1.8 T. The charge identification efficiency for muons was found to be >90% except for large zenith angles. [ABSTRACT FROM PUBLISHER]

The Mu2e experiment at Fermilab is designed to explore charged lepton flavor violation by searching for muon-to-electron conversion. The magnetic field generated by a system of solenoids is a crucial component of Mu2e and requires accurate characterization to detect any potential flaws and to produce a detailed field map. In order to design and build a precise field mapping system consisting of Hall and NMR probes, tolerances and precision for such a system need to be evaluated. To generate a final magnetic field map of the Mu2e solenoids, a continuous field has to be extracted from a discrete set of measurement points. A design for the Mu2e field mapping hardware, and results from simulations to specify parameters for Hall and NMR probes are presented. A fitting procedure for the analytical treatment of our expected magnetic measurements is introduced. [ABSTRACT FROM PUBLISHER]

The Mu2e experiment at Fermilab has been approved by the Department of Energy to proceed with the development of the preliminary design. Integral to the success of Mu2e is the superconducting solenoid system. One of the three major solenoids is the detector solenoid that houses the stopping target and the detectors. The goal of the detector solenoid team is to produce detailed design specifications that are sufficient for vendors to produce the final design drawings, tooling and fabrication procedures and proceed to production. In this paper we summarize the reference design of the detector solenoid. [ABSTRACT FROM PUBLISHER]

The heavy-ion program at the Large Hadron Collider has been commenced in November 2010 by three experiments including ATLAS, a multipurpose detector. It was originally constructed to study high-energy proton-proton collisions but now it also proves to be an excellent tool for studying nuclear interactions. In these proceedings results from the lead- lead run at √sNN = 2:76 TeV based on the minimum-bias data sample are reviewed. In particular, an observation of the centrality-dependent dijet asymmetry is reported. Also a centrality-dependent suppression in the yield of J/ψ mesons decaying to μ+μ- pairs is discussed along with an observation of the Z boson production. These evidences may bring new insight to the dynamics of heavy-ion collisions. [ABSTRACT FROM AUTHOR]

An intense muon beam is mandatory for next-generation experiments to search for lepton flavor violating processes in the muon sector. The COMET experiment, J-PARC E21, aims to search for muon to electron conversion with an unprecedented sensitivity. All the components of the experiment, such as the pion production target, the muon stopping target and the tracker are embedded in superconducting solenoids, resulting in a total length longer than 30 m. The pions are captured in a 5 T solenoid magnet with a diameter of 1.3 m, and decay to muons in the subsequent 3 T toroidal magnets over a length of 10 m. The pion capture solenoid is designed to be as small as possible, however, thick shielding is necessary within the solenoid to avoid severe radiation from the target. Aluminum-stabilized NbTi superconducting wire is employed to reduce the cold mass and energy deposited in it. The damage of the conductor of the coils should be estimated carefully, since the expected neutron fluence reaches 10^22\ neutrons/m^2. This paper describes the design of the solenoid magnets and R&D programs. [ABSTRACT FROM AUTHOR]

A measurement is presented of inelastic photo- and electroproduction of J/ ψ mesons in ep scattering at HERA. The data were recorded with the H1 detector in the period from 2004 to 2007. Single and double differential cross sections are determined and the helicity distributions of the J/ ψ mesons are analysed. The results are compared to theoretical predictions in the colour singlet model and in the framework of non-relativistic QCD. Calculations in the colour singlet model using a k factorisation ansatz are able to give a good description of the data, while colour singlet model calculations to next-to-leading order in collinear factorisation underestimate the data. [ABSTRACT FROM AUTHOR]

We search for ψ(3770)→ π+ π− η, K+ K− η, $p\bar{p}\eta$ , ρ0 π+ π− η, K+ K− π+ π− η, $p\bar{p}\pi^{+}\pi^{-}\eta$ , $p\bar{p}K^{+}K^{-}\eta$ and $p\bar{p}K^{+}K^{-}\pi^{0}$ using data samples of 17.3 and 6.5 pb−1 integrated luminosities recorded at the center-of-mass energies of 3.773 and 3.65 GeV, respectively, by the BES-II detector operating at the BEPC collider. We obtain cross section measurements at both energies and upper limits on ψ(3770) decay branching fractions to the final states studied. [ABSTRACT FROM AUTHOR]

We discuss the ICARUS T600 detector capabilities in electromagnetic shower reconstruction through the analysis of a sample of 212 events, coming from the 2001 Pavia surface test run, of hadronic interactions leading to the production of π0 mesons. Methods of shower energy and shower direction measurements were developed and the invariant mass of the photon pairs was reconstructed. The (γ,γ) invariant mass was found to be consistent with the value of the π0 mass. The resolution of the reconstructed π0 mass was found to be equal to 27.3%. An improved analysis, carried out in order to clean the full event sample from the events measured in the crowded environment, mostly due to the trigger conditions, gave a π0 mass resolution of 16.1%, significantly better than the one evaluated for the full event sample. The trigger requirement of the coincidence of at least four photo-multiplier signals favored the selection of events with a strong pile up of cosmic ray tracks and interactions. Hence a number of candidate π0 events were heavily contaminated by other tracks and had to be rejected. Monte Carlo simulations of events with π0 production in hadronic and neutrino interactions confirmed the validity of the shower energy and shower direction reconstruction methods applied to the real data. [ABSTRACT FROM AUTHOR]

We report a search for narrow resonances, produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0 GeV/ c2. The data, collected with the CDF II detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630 pb−1. We use the dimuon invariant mass distribution to set 90% upper credible limits of about 1% to the ratio of the production cross section times muonic branching fraction of possible narrow resonances to that of the ϒ(1S) meson. [ABSTRACT FROM AUTHOR]

Using the data of about 33 pb-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied the exclusive semileptonic decays D+→K-π+e+νe, D0→K̄0π-e+νe, D+→K̄*0e+νe and D0→K*-e+νe. The absolute branching fractions for the decays are measured to be BF(D+→K-π+e+νe)=(3.50±0.75±0.27)%, BF(D0→K̄0π-e+νe)=(2.61±1.04±0.28)%, BF(D+→K̄*0e+νe)=(5.06±1.21±0.40)% and BF(D0→K*-e+νe)=(2.87±1.48±0.39)%. The ratio of the vector to pseudoscalar semileptonic decay rates Γ(D+→K̄*0e+νe)/Γ(D+→K̄0e+νe) is determined to be 0.57±0.17±0.02. [ABSTRACT FROM AUTHOR]

Using a data sample of integrated luminosity of about 33 pb-1 collected around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic decays D+→φe+νe, D+→φμ+νμ and the hadronic decay D+→φπ+ are studied. The upper limits of the branching fractions are set to be BF(D+→φe+νe)<2.01% and BF(D+→φμ+νμ)<2.04% at the 90% confidence level. The ratio of the branching fractions for D+→φπ+ relative to D+→K-π+π+ is measured to be 0.057±0.011±0.003. In addition, the branching fraction for D+→φπ+ is obtained to be (5.2±1.0±0.4)×10-3. [ABSTRACT FROM AUTHOR]

Using a data sample of integrated luminosity of about 33 pb-1 collected around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic decays D+→φe+νe, D+→φμ+νμ and the hadronic decay D+→φπ+ are studied. The upper limits of the branching fractions are set to be BF(D+→φe+νe)<2.01% and BF(D+→φμ+νμ)<2.04% at the 90% confidence level. The ratio of the branching fractions for D+→φπ+ relative to D+→K-π+π+ is measured to be 0.057±0.011±0.003. In addition, the branching fraction for D+→φπ+ is obtained to be (5.2±1.0±0.4)×10-3. [ABSTRACT FROM AUTHOR]

Using the data of about 33 pb-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied the exclusive semileptonic decays D+→K-π+e+νe, D0→K̄0π-e+νe, D+→K̄*0e+νe and D0→K*-e+νe. The absolute branching fractions for the decays are measured to be BF(D+→K-π+e+νe)=(3.50±0.75±0.27)%, BF(D0→K̄0π-e+νe)=(2.61±1.04±0.28)%, BF(D+→K̄*0e+νe)=(5.06±1.21±0.40)% and BF(D0→K*-e+νe)=(2.87±1.48±0.39)%. The ratio of the vector to pseudoscalar semileptonic decay rates Γ(D+→K̄*0e+νe)/Γ(D+→K̄0e+νe) is determined to be 0.57±0.17±0.02. [ABSTRACT FROM AUTHOR]

LHCb is a dedicated experiment to study CP violation and other rare processes in the B meson system at LHC. It is designed to exploit the large sample of Bd and Bs mesons available at LHC by having a trigger system efficient for both leptonic and hadronic final states, particle identification capability over large momentum range and excellent decay time resolution. Recently, the detector has been reoptimized in order to reduce the material budget and to improve the trigger performance. Construction of various detector components is well advancing and the experiment is expected to be ready for data taking from the beginning of the LHC operation. PACS: 25.70.Ef – 21.60.Gx – 27.30.+t [ABSTRACT FROM AUTHOR]

At the design luminosity of 1034 cm-2 s-1, about 106 b&bmacr; pairs are expected to be produced every second at the Large Hadron Collider. With such huge statistics and the precise tracking of the CMS detector B mesons can be investigated for CP violation, Bs0-&Bmacr;s0 mixing and rare decays. The trigger, however, cannot retain all b&bmacr; events for a later selection of exclusive B decays. A dedicated trigger strategy, which uses tracking immediately after the first trigger stage, is presented and results on few important benchmark channels are given. [ABSTRACT FROM AUTHOR]

The electronic width of the J/ψ meson and its product by the branching fractions of J/ψ meson decay to hadrons and electrons measured with the KEDR detector at the VEPP-4M e+e− collider have been reported in ref. [1]. [ABSTRACT FROM AUTHOR]

Based on a sample of 300 million K S mesons produced in ϕ → K L K S decays recorded by the KLOE experiment at the DAΦNE e + e − collider we have measured the branching fraction for the decay K S → π μ ν. The K S mesons are identified by the interaction of K L mesons in the detector. The K S → π μ ν decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of K L → π μ ν decays. A fit to the reconstructed muon mass distribution finds 7223 ± 180 signal events. Normalising to the K S → π + π − decay events the result for the branching fraction is B (K S → π μ ν) = (4.56 ± 0.11 stat ± 0.17 syst) × 10 − 4. It is the first measurement of this decay mode and the result allows an independent determination of | V u s | and a test of the lepton-flavour universality. [ABSTRACT FROM AUTHOR]

The four decay modes D 0 → ϕ π 0 , D 0 → ϕ η , D + → ϕ π + , and D + → ϕ K + are studied by using a data sample taken at the centre-of-mass energy s = 3.773 GeV with the BESIII detector, corresponding to an integrated luminosity of 2.93 fb−1. The branching fractions of the first three decay modes are measured to be B (D 0 → ϕ π 0) = (1.168 ± 0.028 ± 0.028) × 10 − 3 , B (D 0 → ϕ η) = (1.81 ± 0.46 ± 0.06) × 10 − 4 , and B (D + → ϕ π +) = (5.70 ± 0.05 ± 0.13) × 10 − 3 , respectively, where the first uncertainties are statistical and the second are systematic. In addition, the upper limit of the branching fraction for D + → ϕ K + is given to be 2.1 × 10 − 5 at the 90% confidence level. The ratio of B (D 0 → ϕ π 0) to B (D + → ϕ π +) is calculated to be (20.49 ± 0.50 ± 0.45) % , which is consistent with the theoretical prediction based on isospin symmetry between these two decay modes. [ABSTRACT FROM AUTHOR]

Decays of B s 0 and B ‾ 0 s mesons into J / ψ π + π − final states are studied in a data sample corresponding to 1.9 fb−1 of integrated luminosity collected with the LHCb detector in 13 TeV pp collisions. A time-dependent amplitude analysis is used to determine the final-state resonance contributions, the CP -violating phase ϕ s = − 0.057 ± 0.060 ± 0.011 rad, the decay-width difference between the heavier mass B s 0 eigenstate and the B 0 meson of − 0.050 ± 0.004 ± 0.004 ps−1, and the CP -violating parameter | λ | = 1.01 − 0.06 + 0.08 ± 0.03 , where the first uncertainty is statistical and the second systematic. These results are combined with previous LHCb measurements in the same decay channel using 7 TeV and 8 TeV pp collisions obtaining ϕ s = 0.002 ± 0.044 ± 0.012 rad, and | λ | = 0.949 ± 0.036 ± 0.019. [ABSTRACT FROM AUTHOR]

A model for exclusive diffractive resonance production in proton-proton collisions at high energies is presented. This model is able to predict double differential distributions with respect to the mass and the transverse momentum of the produced resonance in the mass region M2≲ 5 GeV. The model is based on convoluting the Pomeron distribution in the proton with the Pomeron-Pomeron-meson total cross section. The Pomeron-Pomeron-meson cross section is saturated by direct-channel contributions from the Pomeron as well as from two different f trajectories, accompanied by the isolated f0(500) resonance dominating the M2≲1 GeV region. A slowly varying background is taken into account. [ABSTRACT FROM AUTHOR]