JINST

A novel method to reconstruct the energy of hadronic showersin the CMS High Granularity Calorimeter (HGCAL) is presented. TheHGCAL is a sampling calorimeter with very fine transverse andlongitudinal granularity. The active media are silicon sensors andscintillator tiles readout by SiPMs and the absorbers are acombination of lead and Cu/CuW in the electromagnetic section, andsteel in the hadronic section. The shower reconstruction method isbased on graph neural networks and it makes use of a dynamicreduction network architecture. It is shown that the algorithm isable to capture and mitigate the main effects that normally hinderthe reconstruction of hadronic showers using classicalreconstruction methods, by compensating for fluctuations in themultiplicity, energy, and spatial distributions of the shower'sconstituents. The performance of the algorithm is evaluated usingtest beam data collected in 2018 prototype of the CMS HGCALaccompanied by a section of the CALICE AHCAL prototype. Thecapability of the method to mitigate the impact of energy leakagefrom the calorimeter is also demonstrated.

JETP Lett.

The new version of the SANCphot integrator has been developed for fast and stable numerical calculations up to two loops for polarized light-by-light scattering. One-loop modules based on the helicity formalism with massive particles and two-loop modules with massless particles inside the loops are used. The presented study is driven by the potential of polarized photon beams to probe the high energy region. This study is a contribution to the research program of the CEPC project being under development in China.

Phys. Rev. C

This paper describes a measurement of the jet radius dependence of the dijet momentum balance between leading back-to-back jets in $1.72{\mathrm{nb}}^{-1}$ of $\text{Pb}+\text{Pb}$ collisions collected in 2018 and $255{\mathrm{pb}}^{-1}$ of $pp$ collisions collected in 2017 by the ATLAS detector at the LHC. Both datasets were collected at $\sqrt{s_{\text{NN}}}=5.02$ TeV. Jets are reconstructed using the anti-$k_t$ algorithm with jet radius parameters $R=0.2$, 0.3, 0.4, 0.5, and 0.6. The dijet momentum balance distributions are constructed for leading jets with transverse momentum $p_{\text{T}}$ from 100 to 562 GeV for $R=0.2$, 0.3, and 0.4 jets, and from 158 to 562 GeV for $R=0.5$ and 0.6 jets. The absolutely normalized dijet momentum balance distributions are constructed to compare measurements of the dijet yields in $\text{Pb}+\text{Pb}$ collisions directly to the dijet cross sections in $pp$ collisions. For all jet radii considered here, there is a suppression of more balanced dijets in $\text{Pb}+\text{Pb}$ collisions compared with $pp$ collisions, while for more imbalanced dijets there is an enhancement. There is a jet radius dependence to the dijet yields, being stronger for more imbalanced dijets than for more balanced dijets. Additionally, jet pair nuclear modification factors are measured. The subleading jet yields are found to be more suppressed than leading jet yields in dijets. A jet radius dependence of the pair nuclear modification factors is observed, with the suppression decreasing with increasing jet radius. These measurements provide new constraints on jet quenching scenarios in the quark-gluon plasma.

Phys.Rev.Res.

Neutrinoless double beta decay is one of the most sensitive probes for new physics beyond the Standard Model of particle physics. One of the isotopes under investigation is ${}^{136}\mathrm{Xe}$, which would double beta decay into ${}^{136}\mathrm{Ba}$. Detecting the single ${}^{136}\mathrm{Ba}$ daughter provides a sort of ultimate tool in the discrimination against backgrounds. Previous work demonstrated the ability to perform single atom imaging of Ba atoms in a single-vacancy site of a solid xenon matrix. In this paper, the effort to identify signal from individual barium atoms is extended to Ba atoms in a hexa-vacancy site in the matrix and is achieved despite increased photobleaching in this site. Abrupt fluorescence turn-off of a single Ba atom is also observed. Significant recovery of fluorescence signal lost through photobleaching is demonstrated upon annealing of Ba deposits in the Xe ice. Following annealing, it is observed that Ba atoms in the hexa-vacancy site exhibit antibleaching while Ba atoms in the tetra-vacancy site exhibit bleaching. This may be evidence for a matrix site transfer upon laser excitation. Our findings offer a path of continued research toward tagging of Ba daughters in all significant sites in solid xenon.

JHEP

A search is presented for new particles produced in proton-proton collisions at a centre-of-mass energy of 13 TeV that result in final states comprising a massive vector (W or Z) boson that decays hadronically and large missing transverse momentum. The data sample was collected with the ATLAS experiment at the Large Hadron Collider from 2015 to 2018 and corresponds to an integrated luminosity of 140 fb$^{−1}$. No significant excess over the Standard Model expectation is observed. Model-independent 95% confidence-level limits on the visible cross-section that range from 0.3 fb to 79.5 fb are obtained for non-Standard-Model processes. Exclusion limits are also presented for models with axion-like particles, for two-Higgs-doublet models with a pseudo-scalar mediator between the Standard Model and the dark sector, for the invisible decay of the Higgs boson and for pair-produced weakly interacting dark matter candidates.[graphic not available: see fulltext]

Phys.Part.Nucl.Lett.

JINR in collaboration with the St. Petersburg-based Efremov Institute of Electrophysical Apparatus (NIIEFA) is developing a superconducting isochronous cyclotron MSC230, which is intended to conduct research in radiobiology and to develop proton flash radiotherapy techniques. In relation to this, formation of a high-intensity proton beam with the energy selectable in a range of 120–230 MeV, a dose rate of 50–100 Gy/s, and homogeneous in cross section with a diameter of 13–15 cm at the new accelerator is explored. Results of modeling by the Monte Carlo method and measurements of the depth-dose distributions of a proton beam, the energy spectrum of which is modified to obtain an extended homogeneous plateau at the end of the range (spread-out Bragg peak), are presented. This is achieved by using so-called ridge filters. A method for design and manufacturing ridge filters using a 3D printer that can change the length of the plateau in a fairly wide range of values by rotating it relative to the beam axis is presented. The results of the study lend a hope that two sets, each consisting of 5–6 such filters, will be able to span the entire required range of the Bragg peak plateau, and for all values of the selected energy.

Phys.Part.Nucl.Lett.

This paper presents a design of a calibration system for the Light Readout System of the prototype modular Liquid Argon Time-Projection Chamber (LArTPC) of the Near Detector of the Deep Underground Neutrino Experiment (DUNE). The calibration system and its components have been tested at the Joint Institute for Nuclear Research (JINR) and during the prototype LArTPC trials conducted at the University of Bern, Switzerland. The results demonstrate that the system fulfills its intended functionality, allowing for the calibration of the photodetectors in the light-readout system of the LArTPC and the study of its temporal characteristics.

Phys.Rev.C

The background index (BI) is an important quantity to project and calculate the half-life sensitivity of neutrinoless double-$\beta$ decay $\left(0\nu \beta \beta \right)$ experiments. An analysis framework is presented to calculate the BI using the specific activities, masses, and simulated efficiencies of an experiments components as distributions. This Bayesian framework includes a unified approach to combine specific activities from assay. Monte Carlo uncertainty propagation is used to build a BI distribution from the specific activity, mass, and efficiency distributions. This method is applied to the Majorana Demonstrator, which deployed arrays of high-purity Ge detectors enriched in ${}^{76}\mathrm{Ge}$ to search for $0\nu \beta \beta$. The original assay-based projection is requantified in the new framework, using the as-built geometry of the Demonstrator and additional assay information. While 47% higher than the original projection, the resulting BI of $[8.95\pm 0.36]\times {10}^{-4}\text{cts/(keV}\text{kg}\text{yr)}$ from the ${}^{232}\mathrm{Th}$ and ${}^{238}\mathrm{U}$ decay chains does not account for the higher-than-expected BI observed by the Demonstrator. This method enables us to demonstrate the statistical incompatibility between the Demonstrator's observed background and the assay results.

Phys. Part. Nucl. Lett.

One way to increase the sensitivity of the precision laser inclinometer (PLI) is to change over from the photovoltaic mode to the reverse-biased photodiode mode. This allows a broader linear range and an improved signal-to-noise ratio. Additionally, this approach enables the use of lower resolution ADCs (14–16 bit instead of 24 bit), which significantly reduces the cost of the device. A study of the Hamamatsu S12915-1010R/66R, Thorlabs FDS-100, and Hamamatsu S3204-08 photodiodes is conducted to determine their linear range of operation in the photovoltaic and photodiode modes. The noise level of the CPLI readout channels is measured using closed photodiodes, and two modes of operation of the photodiodes in the CPLI on the signal channels are investigated. The research results indicate the possibility of using this mode of operation of photodiodes in the CPLI.

JINST

The CERN LHC provided proton and heavy ion collisions duringits Run 2 operation period from 2015 to 2018. Proton-protoncollisions reached a peak instantaneous luminosity of2.1× 10$^{34}$ cm$^{-2}$s$^{-1}$, twice the initialdesign value, at √(s)=13 TeV. The CMS experimentrecords a subset of the collisions for further processing as part ofits online selection of data for physics analyses, using a two-leveltrigger system: the Level-1 trigger, implemented in custom-designedelectronics, and the high-level trigger, a streamlined version ofthe offline reconstruction software running on a large computerfarm. This paper presents the performance of the CMS high-leveltrigger system during LHC Run 2 for physics objects, such asleptons, jets, and missing transverse momentum, which meet the broadneeds of the CMS physics program and the challenge of the evolvingLHC and detector conditions. Sophisticated algorithms that wereoriginally used in offline reconstruction were deployedonline. Highlights include a machine-learning b tagging algorithmand a reconstruction algorithm for tau leptons that decayhadronically.

JHEP

Using 7.33 fb$^{−1}$ of e$^{+}$e$^{−}$ collision data samples collected with the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, we search for the radiative decay ${D}_s^{+}\to \gamma \rho {(770)}^{+}$ for the first time. A hint of ${D}_s^{+}\to \gamma \rho {(770)}^{+}$ is observed with a statistical significance of 2.5σ. The branching fraction of ${D}_s^{+}\to \gamma \rho {(770)}^{+}$ is measured to be (2.2 ± 0.9$_{stat.}$ ± 0.2$_{syst.}$) × 10$^{−4}$, corresponding to an upper limit of 6.1 × 10$^{−4}$ at the 90% confidence level.

JHEP

The radiative decays χ$_{c1}$(3872) → ψ(2S) γ and χ$_{c1}$(3872) → J/ψγ are used to probe the nature of the χ$_{c1}$(3872) state using proton-proton collision data collected with the LHCb detector, corresponding to an integrated luminosity of 9 fb$^{−1}$. Using the B$^{+}$ → χ$_{c1}$(3872)K$^{+}$ decay, the χ$_{c1}$(3872) → ψ(2S) γ process is observed for the first time and the ratio of its partial width to that of the χ$_{c1}$(3872) → J/ψγ decay is measured to beParseError: KaTeX parse error: Undefined control sequence: \uppsi at position 35: …_{c1}(3872)\to \̲u̲p̲p̲s̲i̲ ̲\left(2\textrm{…where the first uncertainty is statistical, the second systematic and the third is due to the uncertainties on the branching fractions of the ψ(2S) and J/ψ mesons. The measured ratio makes the interpretation of the χ$_{c1}$(3872) state as a pure D$^{0} {\overline{\textrm{D}}}^{\ast 0}$ + ${\overline{\textrm{D}}}^0$ D$^{*0}$ molecule questionable and strongly indicates a sizeable compact charmonium or tetraquark component within the χ$_{c1}$(3872) state.[graphic not available: see fulltext]

Phys.Lett.B

A combination of searches for singly and doubly charged Higgs bosons, $H^{\pm }$ and $H^{\pm \pm }$, produced via vector-boson fusion is performed using 140 fb⁻¹ of proton–proton collisions at a centre-of-mass energy of 13 TeV, collected with the ATLAS detector during Run 2 of the Large Hadron Collider. Searches targeting decays to massive vector bosons in leptonic final states (electrons or muons) are considered. New constraints are reported on the production cross-section times branching fraction for charged Higgs boson masses between 200 GeV and 3000 GeV. The results are interpreted in the context of the Georgi-Machacek model for which the most stringent constraints to date are set for the masses considered in the combination.

Eur. Phys. J. C

The Monument experiment measures ordinary muon capture (OMC) on isotopes relevant for neutrinoless double-beta ($0\nu \beta \beta$) decay and nuclear astrophysics. OMC is a particularly attractive tool for improving the theoretical description of $0\nu \beta \beta$ decay. It involves similar momentum transfers and allows testing the virtual transitions involved in $0\nu \beta \beta$ decay against experimental data. During the 2021 campaign, Monument studied OMC on $^{76}$Se and $^{136}$Ba, the isotopes relevant for next-generation $0\nu \beta \beta$ decay searches, like Legend and nEXO. The experimental setup has been designed to accurately extract the total and partial muon capture rates, which requires precise reconstruction of energies and time-dependent intensities of the OMC-related $\gamma$ rays. The setup also includes a veto counter system to allow selecting a clean sample of OMC events. This work provides a detailed description of the Monument setup operated during the 2021 campaign, its two DAQ systems, calibration and analysis approaches, and summarises the achieved detector performance. Future improvements are also discussed.

JHEP

This paper reports the observation of top-quark pair production in proton-lead collisions in the ATLAS experiment at the Large Hadron Collider. The measurement is performed using 165 nb$^{−1}$ of p+Pb data collected at $\sqrt{s_{\textrm{NN}}}$ = 8.16 TeV in 2016. Events are categorised in two analysis channels, consisting of either events with exactly one lepton (electron or muon) and at least four jets, or events with two opposite-charge leptons and at least two jets. In both channels at least one b-tagged jet is also required. Top-quark pair production is observed with a significance over five standard deviations in each channel. The top-quark pair production cross-section is measured to be ${\sigma}_{t\overline{t}}=58.1\pm 2.0{\left(\textrm{stat}.\right)}_{-4.4}^{+4.8}\left(\textrm{syst}.\right)$ nb, with a total uncertainty of 9%. In addition, the nuclear modification factor is measured to be ${R}_{p\textrm{A}}=1.090\pm 0.039{\left(\textrm{stat}.\right)}_{-0.087}^{+0.094}\left(\textrm{syst}.\right)$. The measurements are found to be in good agreement with theory predictions involving nuclear parton distribution functions.[graphic not available: see fulltext]

JHEP

Measurements of the Higgs boson production times decay rates and differential cross-sections have recently been performed by the ATLAS experiment in several decay channels using up to 139 fb$^{−1}$ of proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded at the Large Hadron Collider. This paper presents multiple interpretations of these Higgs boson measurements. Measurements of production-mode cross-sections, simplified template cross-sections and fiducial differential cross-sections in different decay channels are reparameterised in terms of the impact of Standard Model effective field theory operators, and constraints are reported on the corresponding Wilson coefficients. Production and decay rate measurements are interpreted in UV-complete extensions of the Standard Model, namely the two-Higgs-doublet model (2HDM) near the alignment limit and the Minimal Supersymmetric Standard Model (MSSM) for various MSSM benchmark scenarios. The constraints on the 2HDM parameters (cos(β − α), tanβ) and the MSSM parameters (m$_{A}$, tanβ) are complementary to those obtained from direct searches for additional Higgs bosons.[graphic not available: see fulltext]

Phys. Rev. D

Dark matter may induce an event in an Earth-based detector, and its event rate is predicted to show an annual modulation as a result of the Earth’s orbital motion around the Sun. We searched for this modulation signature using the ionization signal of the DarkSide-50 liquid argon time projection chamber. No significant signature compatible with dark matter is observed in the electron recoil equivalent energy range above $40{\mathrm{eV}}_{\mathrm{ee}}$, the lowest threshold ever achieved in such a search.

Phys. Rev. Lett.

This Letter reports a search for charge-parity ($CP$) symmetry violating nonstandard interactions (NSI) of neutrinos with matter using the NOvA Experiment, and examines their effects on the determination of the standard oscillation parameters. Data from ${\nu }_{\mu }({\overline{\nu }}_{\mu })\to {\nu }_{\mu }({\overline{\nu }}_{\mu })$ and ${\nu }_{\mu }({\overline{\nu }}_{\mu })\to {\nu }_e({\overline{\nu }}_e)$ oscillation channels are used to measure the effect of the NSI parameters ${ϵ}_{e\mu }$ and ${ϵ}_{e\tau }$. With 90% CL the magnitudes of the NSI couplings are constrained to be $|{ϵ}_{e\mu }|\lesssim 0.3$ and $|{ϵ}_{e\tau }|\lesssim 0.4$. A degeneracy at $|{ϵ}_{e\tau }|\approx 1.8$ is reported, and we observe that the presence of NSI limits sensitivity to the standard $CP$ phase ${\delta }_{CP}$.

JINST

The novel SoLAr concept aims to extend sensitivities ofliquid-argon neutrino detectors down to the MeV scale fornext-generation detectors. SoLAr plans to accomplish this with aliquid-argon time projection chamber that employs an anode planewith dual charge and light readout, which enables precision matchingof light and charge signals for data acquisition and reconstructionpurposes. We present the results of a first demonstration of theSoLAr detector concept with a small-scale prototype detectorintegrating a pixel-based charge readout and siliconphotomultipliers on a shared printed circuit board. We discuss thedesign of the prototype, and its operation and performance,highlighting the capability of such a detector design.

Phys. Rev. Lett.

Searches for pair-produced multijet signatures using data corresponding to an integrated luminosity of $128{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ are presented. A data scouting technique is employed to record events with low jet scalar transverse momentum sum values. The electroweak production of particles predicted in $R$-parity violating supersymmetric models is probed for the first time with fully hadronic final states. This is the first search for prompt hadronically decaying mass-degenerate higgsinos, and extends current exclusions on $R$-parity violating top squarks and gluinos.

Nucl. Instrum. Meth. A

The “muon-to-electron conversion” (Mu2e) experiment at Fermilab will search for the Charged Lepton Flavour Violating neutrino-less coherent conversion of a muon into an electron in the field of an aluminum nucleus. The observation of this process would be the unambiguous evidence of physics beyond the Standard Model. The detector has been designed as a state-of-the-art crystal calorimeter and employs 1348 pure Cesium Iodide (CsI) crystals readout by UV-extended silicon photosensors and fast front-end and digitization electronics. A design consisting of two identical annular matrices (named “disks”) positioned at the relative distance of 70 cm, downstream the aluminum target along the muon beamline, satisfies the Mu2e physics requirements. The hostile Mu2e operational conditions, in terms of radiation levels (total ionizing dose of 90 krad and a neutron fluence of $5x10^{12}n/c{m}^2@1MeVeq\left(Si\right)/y$), magnetic field intensity (1 T) and vacuum level ($10^{-4}$ Torr) have posed tight constraints on the design of the detector mechanical structures and materials choice. The support structure of the two 674 crystal matrices employs two aluminum hollow rings and parts made of open-cell vacuum-compatible carbon fiber. The photosensors and service front-end electronics for each crystal are assembled in a unique mechanical unit inserted in a machined copper holder. The 674 units are supported by a machined plate made of vacuum-compatible plastic material. The plate also integrates the cooling system made of a network of copper lines flowing a low temperature radiation-hard fluid and placed in thermal contact with the copper holders. The data acquisition electronics is hosted in aluminum custom crates positioned on the external lateral surface of the two disks. The crates also integrate the electronics cooling system.

JHEP

Using e$^{+}$e$^{−}$ collision data collected by the BESIII detector at BEPCII corresponding to an integrated luminosity of 30 fb$^{−1}$, we measure Born cross sections and effective form factors for the process ${e}^{+}{e}^{-}\to {\Xi}^0{\overline{\Xi}}^0$ at forty-five center-of-mass energies between 3.51 and 4.95 GeV. The dressed cross section is fitted, assuming a power-law function plus a charmonium(-like) state, i.e., ψ(3770), ψ(4040), ψ(4160), ψ(4230), ψ(4360), ψ(4415) or ψ(4660). No significant charmonium(-like) state decaying into ${\Xi}^0{\overline{\Xi}}^0$ is observed. Upper limits at the 90% confidence level on the product of the branching fraction and the electronic partial width are provided for each decay. In addition, ratios of the Born cross sections and the effective form factors for ${e}^{+}{e}^{-}\to {\Xi}^0{\overline{\Xi}}^0$ and ${e}^{+}{e}^{-}\to {\Xi}^{-}{\overline{\Xi}}^{+}$ are also presented to test isospin symmetry and the vector meson dominance model.[graphic not available: see fulltext]

Comput.Softw.Big Sci.

This paper describes the Combine software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run Combine and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of Combine. However, the online documentation referenced within this paper provides an up-to-date and complete user guide.

JHEP

A search for the resonant production of a heavy scalar X decaying into a Higgs boson and a new lighter scalar S, through the process X → S(→$b\overline{b}$)H(→γγ), where the two photons are consistent with the Higgs boson decay, is performed. The search is conducted using an integrated luminosity of 140 fb$^{−1}$ of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The search is performed over the mass range 170 ≤ m$_{X}$ ≤ 1000 GeV and 15 ≤ m$_{S}$ ≤ 500 GeV. Parameterised neural networks are used to enhance the signal purity and to achieve continuous sensitivity in a domain of the (m$_{X}$, m$_{S}$) plane. No significant excess above the expected background is found and 95% CL upper limits are set on the cross section times branching ratio, ranging from 39 fb to 0.09 fb. The largest deviation from the background-only expectation occurs for (m$_{X}$, m$_{S}$) = (575, 200) GeV with a local (global) significance of 3.5 (2.0) standard deviations.

Selecta Math.

In this paper we assign a family of n coupled line ensembles to any $U_q (\widehat{\mathfrak {sl}}_{n+1})$ colored stochastic fused vertex model, which satisfies two properties. First, the joint law of their top curves coincides with that of the colored height functions for the vertex model. Second, the n line ensembles satisfy an explicit Gibbs property prescribing their laws if all but a few of their curves are conditioned upon. We further describe several examples of such families of line ensembles, including the ones for the colored stochastic six-vertex and q-boson models. The appendices (which may be of independent interest) include an explanation of how the $U_q (\widehat{\mathfrak {sl}}_{n+1})$ colored stochastic fused vertex model degenerates to the log-gamma polymer, and an effective rate of convergence of the colored stochastic six-vertex model to the colored ASEP.