Phys. Rev. Lett.

Using an 185-kg NaI[Tl] array, COHERENT has measured the inclusive electron-neutrino charged-current cross section on ${}^{127}\mathrm{I}$ with pion decay-at-rest neutrinos produced by the Spallation Neutron Source at Oak Ridge National Laboratory. Iodine is one the heaviest targets for which low-energy ($\le 50\mathrm{MeV}$) inelastic neutrino-nucleus processes have been measured, and this is the first measurement of its inclusive cross section. After a five-year detector exposure, COHERENT reports a flux-averaged cross section for electron neutrinos of ${9.2}_{-1.8}^{+2.1}\times {10}^{-40}{\mathrm{cm}}^2$. This corresponds to a value that is $\sim 41\%$ lower than predicted using the MARLEY event generator with a measured Gamow-Teller strength distribution. In addition, the observed visible spectrum from charged-current scattering on ${}^{127}\mathrm{I}$ has been measured between 10 and 55 MeV, and the exclusive zero-neutron and one-or-more-neutron emission cross sections are measured to be ${5.2}_{-3.1}^{+3.4}\times {10}^{-40}$ and ${2.2}_{-0.5}^{+0.4}\times {10}^{-40}{\mathrm{cm}}^2$, respectively.

Eur. Phys. J. A

Elastic and inelastic scattering angular distributions (ADs) for the $^{6}$Li + $^{144}$Sm system in the 21–45 MeV energy range are analyzed with a Woods-Saxon phenomenological and two microscopic optical potentials, with one derived from the São Paulo formulation and the other from cluster folding of realistic alpha and deuteron potentials. Energy-dependent real, J$_{V}$, and imaginary, J$_{W}$, potential volume integrals are extracted from each potential system. It is shown that their variation in the region of the Coulomb barrier displays the normal threshold anomaly of strong coupling between the real and imaginary potentials. The reduced energy dependence on the extracted reduced reaction cross sections for the $^{6}$Li + $^{144}$Sm system is presented and compared to the calculated one using Wong’s formula. The strength and energy dependence of the inelastic ADs are reasonably described using the adopted potentials within the framework of the coupled channels method.

Eur. Phys. J. C

Searches for long-lived particles (LLPs) are among the most promising avenues for discovering physics beyond the Standard Model at the Large Hadron Collider (LHC). However, displaced signatures are notoriously difficult to identify due to their ability to evade standard object reconstruction strategies. In particular, the ATLAS track reconstruction applies strict pointing requirements which limit sensitivity to charged particles originating far from the primary interaction point. To recover efficiency for LLPs decaying within the tracking detector volume, the ATLAS Collaboration employs a dedicated large-radius tracking (LRT) pass with loosened pointing requirements. During Run 2 of the LHC, the LRT implementation produced many incorrectly reconstructed tracks and was therefore only deployed in small subsets of events. In preparation for LHC Run 3, ATLAS has significantly improved both standard and large-radius track reconstruction performance, allowing for LRT to run in all events. This development greatly expands the potential phase-space of LLP searches and streamlines LLP analysis workflows. This paper will highlight the above achievement and report on the readiness of the ATLAS detector for track-based LLP searches in Run 3.

Pisma Zh. Eksp. Teor. Fiz.

In the interaction of a transversely polarized nuclear beam with a tensor-polarized deuteron target, a nonzero value of the component of the total cross section corresponding to this combination of polarizations is an unambiguous signal of $T$-invariance violation while $P$-parity is preserved. The method developed earlier for calculating this component of the total cross section for $pd$ scattering based on the Glauber theory has been generalized by us to the case of $^{3}$He$d$ scattering, and its energy dependence in the range of beam energies 0.1–1 GeV/nucleon has been calculated. It is found that in $^{3}$He$d$ collisions, in contrast to $pd$ scattering, the contribution of only one type of $T$-violating nucleon-nucleon forces dominates, which is essential for extraction of the unknown constant of this interaction from the corresponding data.

Eur. Phys. J. C

A search for pair-produced scalar or vector leptoquarks decaying into a b-quark and a $\tau$-lepton is presented using the full LHC Run 2 (2015–2018) data sample of 139 fb$^{-1}$ collected with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of $\sqrt{s} =13$ TeV. Events in which at least one $\tau$-lepton decays hadronically are considered, and multivariate discriminants are used to extract the signals. No significant deviations from the Standard Model expectation are observed and 95% confidence-level upper limits on the production cross-section are derived as a function of leptoquark mass and branching ratio $\mathcal {B}$ into a $\tau$-lepton and b-quark. For scalar leptoquarks, masses below 1460 GeV are excluded assuming $\mathcal {B}=100$%, while for vector leptoquarks the corresponding limit is 1650 GeV (1910 GeV) in the minimal-coupling (Yang–Mills) scenario.

Front.Phys.(Beijing)

The super τ-charm facility (STCF) is an electron–positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5 × 10$^{35}$ cm$^{−2}$·s$^{−1}$ or higher. The STCF will produce a data sample about a factor of 100 larger than that of the present τ-charm factory — the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R&D and physics case studies.[graphic not available: see fulltext][graphic not available: see fulltext]

JHEP

A search for the production of pairs of heavy Majorana neutrinos (N$_{ℓ}$) from the decays of Z′ bosons is performed using the CMS detector at the LHC. The data were collected in proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV, with an integrated luminosity of 138 fb$^{−1}$. The signature for the search is an excess in the invariant mass distribution of the final-state objects, two same-flavor leptons (e or μ) and at least two jets. No significant excess of events beyond the expected background is observed. Upper limits at 95% confidence level are set on the product of the Z′ production cross section and its branching fraction to a pair of N$_{ℓ}$, as functions of N$_{ℓ}$ and Z′ boson masses (${m}_{{\textrm{N}}_{\ell }}$ and ${m}_{{\textrm{Z}}^{\prime }}$, respectively) for ${m}_{{\textrm{Z}}^{\prime }}$ from 0.4 to 4.6 TeV and ${m}_{{\textrm{N}}_{\ell }}$ from 0.1 TeV to ${m}_{{\textrm{Z}}^{\prime }}$/2. In the theoretical framework of a left-right symmetric model, exclusion bounds in the ${m}_{{\textrm{N}}_{\ell }}$-${m}_{{\textrm{Z}}^{\prime }}$ plane are presented in both the electron and muon channels. The observed upper limit on ${m}_{{\textrm{Z}}^{\prime }}$ reaches up to 4.42 TeV. These are the most restrictive limits to date on the mass of N$_{ℓ}$ as a function of the Z′ boson mass.[graphic not available: see fulltext]

JHEP

A search is presented for single production of a vector-like B quark decaying into a Standard Model b-quark and a Standard Model Higgs boson, which decays into a $b\overline{b}$ pair. The search is carried out in 139 fb$^{−1}$ of $\sqrt{s}$ = 13 TeV proton-proton collision data collected by the ATLAS detector at the LHC between 2015 and 2018. No significant deviation from the Standard Model background prediction is observed, and mass-dependent exclusion limits at the 95% confidence level are set on the resonance production cross-section in several theoretical scenarios determined by the couplings c$_{W}$, c$_{Z}$ and c$_{H}$ between the B quark and the Standard Model W, Z and Higgs bosons, respectively. For a vector-like B occurring as an isospin singlet, the search excludes values of c$_{W}$ greater than 0.45 for a B resonance mass (m$_{B}$) between 1.0 and 1.2 TeV. For 1.2 TeV < m$_{B}$< 2.0 TeV, c$_{W}$ values larger than 0.50–0.65 are excluded. If the B occurs as part of a (B, Y) doublet, the smallest excluded c$_{Z}$ coupling values range between 0.3 and 0.5 across the investigated resonance mass range 1.0 TeV < m$_{B}$< 2.0 TeV.[graphic not available: see fulltext]

JHEP

A search for supersymmetry targeting the direct production of winos and higgsinos is conducted in final states with either two leptons (e or μ) with the same electric charge, or three leptons. The analysis uses 139 fb$^{−1}$ of pp collision data at $\sqrt{s}$ = 13 TeV collected with the ATLAS detector during Run 2 of the Large Hadron Collider. No significant excess over the Standard Model expectation is observed. Simplified and complete models with and without R-parity conservation are considered. In topologies with intermediate states including either Wh or WZ pairs, wino masses up to 525 GeV and 250 GeV are excluded, respectively, for a bino of vanishing mass. Higgsino masses smaller than 440 GeV are excluded in a natural R-parity-violating model with bilinear terms. Upper limits on the production cross section of generic events beyond the Standard Model as low as 40 ab are obtained in signal regions optimised for these models and also for an R-parity-violating scenario with baryon-number-violating higgsino decays into top quarks and jets. The analysis significantly improves sensitivity to supersymmetric models and other processes beyond the Standard Model that may contribute to the considered final states.[graphic not available: see fulltext]

Phys.Rev.Lett.

Using data samples with an integrated luminosity of $5.85{\mathrm{fb}}^{-1}$ collected at center-of-mass energies from 4.61 to 4.95 GeV with the BESIII detector operating at the BEPCII storage ring, we measure the cross section for the process $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$. A new resonance with a mass of $M=4708_{-15}^{+17}\pm 21\mathrm{MeV}/c^2$ and a width of $\mathrm{\Gamma }=126_{-23}^{+27}\pm 30\mathrm{MeV}$ is observed in the energy-dependent line shape of the $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$ cross section with a significance over $5\sigma$. The $K^{+}J/\psi$ system is also investigated to search for charged charmoniumlike states, but no significant $Z_{cs}^{+}$ states are observed. Upper limits on the Born cross sections for $e^{+}{e}^{-}\to K^{-}{Z}_{cs}(3985{)}^{+}/K^{-}{Z}_{cs}(4000{)}^{+}+c.c.$ with $Z_{cs}(3985{)}^{\pm }/Z_{cs}(4000{)}^{\pm }\to K^{\pm }J/\psi$ are reported at 90% confidence levels. The ratio of branching fractions $\{[\mathcal{B}(Z_{cs}(3985{)}^{+}\to K^{+}J/\psi )]/\mathcal{B}[Z_{cs}(3985{)}^{+}\to ({\overline{D}}^0{D}_s^{*+}+{\overline{D}}^{*0}{D}_s^{+})]\}$ is measured to be less than 0.03 at 90% confidence level.

JHEP

Based on 4.5 fb$^{−1}$e$^{+}$e$^{−}$ collision data collected with BESIII detector at seven energy points between 4.600 and 4.699 GeV, the branching fractions for ${\Lambda}_c^{+}\to p\eta$ and ${\Lambda}_c^{+}\to p\omega$ were measured by means of single-tag method. The branching fractions of ${\Lambda}_c^{+}\to p\eta$ and ${\Lambda}_c^{+}\to p\omega$ are determined to be (1.57 ± 0.11$_{stat}$± 0.04$_{syst}$) × 10$^{−3}$ and (1.11 ± 0.20$_{stat}$± 0.07$_{syst}$) × 10$^{−3}$, with a statistical significance of greater than 10σ and 5.7σ, respectively. These results are consistent with the previous measurements by BESIII, LHCb and Belle, and the result of ${\Lambda}_c^{+}\to p\eta$ is the most precise to date.[graphic not available: see fulltext]

JHEP

We present a search for magnetic monopoles and high-electric-charge objects using LHC Run 2 $\sqrt{s}$ = 13 TeV proton-proton collisions recorded by the ATLAS detector. A total integrated luminosity of 138 fb$^{−1}$ was collected by a specialized trigger. No highly ionizing particle candidate was observed. Considering the Drell-Yan and photon-fusion pair production mechanisms as benchmark models, cross-section upper limits are presented for spin-0 and spin-1/2 magnetic monopoles of magnetic charge 1g$_{D}$ and 2g$_{D}$ and for high-electric-charge objects of electric charge 20 ≤ |z| ≤ 100, for masses between 200 GeV and 4000 GeV. The search improves by approximately a factor of three the previous cross-section limits on the Drell-Yan production of magnetic monopoles and high-electric charge objects. Also, the first ATLAS limits on the photon-fusion pair production mechanism of magnetic monopoles and high-electric-charge objects are obtained.[graphic not available: see fulltext]

JINST

A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadron calorimeter during Run 2 (2015–2018) of the LHC. During Run 2, the characteristic bunch-crossing spacing for proton-proton collisions was 25 ns, which resulted in overlapping signals from adjacent crossings. The energy corresponding to a particular bunch crossing of interest is estimated using the known pulse shapes of energy depositions in the calorimeter, which are measured as functions of both energy and time. A variety of algorithms were developed to mitigate the effects of adjacent bunch crossings on local energy reconstruction in the hadron calorimeter in Run 2, and their performance is compared.

Phys.Rev.D

In this paper, we report the first measurement of CNO solar neutrinos by Borexino that uses the correlated integrated directionality (CID) method, exploiting the subdominant Cherenkov light in the liquid scintillator detector. The directional information of the solar origin of the neutrinos is preserved by the early Cherenkov photons from the neutrino scattered electrons and is used to discriminate between signal and background. The directional information is independent from the spectral information on which the previous CNO solar neutrino measurements by Borexino were based, except for the selection of the energy region of interest. While the CNO spectral analysis could only be applied on the Phase-III dataset, the directional analysis can use the complete Borexino data taking period from 2007 to 2021. The absence of CNO neutrinos has been rejected with $>5\sigma$ posterior probability using the Bayesian statistics. The directional CNO measurement is obtained without an external constraint on the ${}^{210}\mathrm{Bi}$ contamination of the liquid scintillator, which was applied in the spectral analysis approach. The final and the most precise CNO measurement of Borexino is then obtained by combining the new CID-based CNO result with an improved spectral fit of the Phase-III dataset. Including the statistical and the systematic errors, the extracted CNO interaction rate is $R(\mathrm{CNO})={6.7}_{-0.8}^{+1.2}\mathrm{cpd}/100\mathrm{tonnes}$. Taking into account the neutrino flavor conversion, the resulting CNO neutrino flux at Earth is ${\mathrm{\Phi }}_{\mathrm{CNO}}={6.7}_{-0.8}^{+1.2}\times {10}^8{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$, which is found to be in agreement with the high metallicity standard solar models. This outcome, combined with the ${}^7\mathrm{Be}$ and ${}^8\mathrm{B}$ fluxes measurements previously obtained by Borexino, can be used to disfavor the low metallicity SSM B16-AGSS09met model at $3.2\sigma$ CL, assuming the SSM B16-GS98 high metallicity model to be true. Also, the sum of C and N abundances in the solar core with respect to the H abundance is evaluated with improved precision, resulting in ${\mathrm{N}}_{\mathrm{CN}}={5.81}_{-0.94}^{+1.22}\times {10}^{-4}$, which is compatible with the high metallicity scenario and exhibits a $2\sigma$ tension with the low metallicity case. The results described in this work reinforce the role of directional Cherenkov light in large-scale liquid scintillator detectors and open up new avenues for the next-generation liquid scintillator or hybrid neutrino experiments. A particular relevance is expected for the latter detectors, which aim to combine the advantages from both Cherenkov-based and scintillation-based detection techniques.

Pisma Zh. Eksp. Teor. Fiz.

The low-$x$ behavior of the linearly polarized gluon density ${{h}_{g}}(x,k_{t}^{2},{{Q}^{2}})$ in nuclei is studied in the rescaling model at small transverse momentum ${{k}_{t}}$.

Eur. Phys. J. C

JEM-EUSO is an international program for the development of space-based Ultra-High Energy Cosmic Ray observatories. The program consists of a series of missions which are either under development or in the data analysis phase. All instruments are based on a wide-field-of-view telescope, which operates in the near-UV range, designed to detect the fluorescence light emitted by extensive air showers in the atmosphere. We describe the simulation software ESAF in the framework of the JEM-EUSO program and explain the physical assumptions used. We present here the implementation of the JEM-EUSO, POEMMA, K-EUSO, TUS, Mini-EUSO, EUSO-SPB1 and EUSO-TA configurations in ESAF. For the first time ESAF simulation outputs are compared with experimental data.

Phys.Lett.B

Semi-visible jets, with a significant contribution to the event's missing transverse momentum, can arise in strongly interacting dark sectors. This results in an event topology where one of the jets can be aligned with the direction of the missing transverse momentum. The first search for semi-visible jets produced via a t-channel mediator exchange is presented. The analysis uses proton-proton collisions with an integrated luminosity of 139 fb⁻¹ and a centre-of-mass energy of 13 TeV, collected with the ATLAS detector during the Run 2 of the LHC. No excess over Standard Model predictions is observed. Assuming a coupling strength of unity between the mediator, a Standard Model quark and a dark quark, mediator masses up to 2.7 TeV are excluded at the 95% confidence level. Upper limits on the coupling strength are also derived.

Phys. Lett. B

The mass of the Higgs boson is measured in the $H\to \gamma \gamma$ decay channel, exploiting the high resolution of the invariant mass of photon pairs reconstructed from the decays of Higgs bosons produced in proton–proton collisions at a centre-of-mass energy $\sqrt{s}=13$ TeV. The dataset was collected between 2015 and 2018 by the ATLAS detector at the Large Hadron Collider, and corresponds to an integrated luminosity of 140 fb⁻¹. The measured value of the Higgs boson mass is $125.17\pm 0.11(\mathrm{stat}.)\pm 0.09(\mathrm{syst}.)$ GeV and is based on an improved energy scale calibration for photons, whose impact on the measurement is about four times smaller than in the previous publication. A combination with the corresponding measurement using 7 and 8 TeV pp collision ATLAS data results in a Higgs boson mass measurement of $125.22\pm 0.11(\mathrm{stat}.)\pm 0.09(\mathrm{syst}.)$ GeV. With an uncertainty of 1.1 per mille, this is currently the most precise measurement of the mass of the Higgs boson from a single decay channel.

JINST

The ATLAS experiment relies on real-time hadronic jetreconstruction and b-tagging to record fully hadronic eventscontaining b-jets. These algorithms require track reconstruction,which is computationally expensive and could overwhelm thehigh-level-trigger farm, even at the reduced event rate that passesthe ATLAS first stage hardware-based trigger. In LHC Run 3, ATLAShas mitigated these computational demands by introducing a fastneural-network-based b-tagger, which acts as a low-precisionfilter using input from hadronic jets and tracks. It runs after ahardware trigger and before the remaining high-level-triggerreconstruction. This design relies on the negligible cost ofneural-network inference as compared to track reconstruction, andthe cost reduction from limiting tracking to specific regions of thedetector. In the case of Standard Model HH → bb̅bb̅, a key signature relying on b-jet triggers, the filter lowers the input rate to the remaininghigh-level trigger by a factor of five at the small cost of reducingthe overall signal efficiency by roughly 2%.

Phys.Lett.B

A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data collected in 2015–2018 at $\sqrt{s}=13$ TeV from pp collisions corresponding to an integrated luminosity of 139 fb⁻¹ are examined. Particles producing anomalously high ionization, consistent with long-lived spin-½ massive particles with electric charges from $|q|=2e$ to $|q|=7e$ are searched for. No statistically significant evidence of such particles is observed, and 95% confidence level cross-section upper limits are calculated and interpreted as the lower mass limits for a Drell–Yan plus photon-fusion production mode. The least stringent limit, 1060 GeV, is obtained for $|q|=2e$ particles, and the most stringent one, 1600 GeV, is for $|q|=6e$ particles.

Phys. Rev. Lett.

We study the process $e^{+}e^{-}\to\Lambda_{c}^{+}\bar{\Lambda}_c^{-}$ at twelve center-of-mass energies from $4.6119$ to $4.9509~\mathrm{GeV}$ using data samples collected by the BESIII detector at the BEPCII collider. The Born cross sections and effective form factors ($|G_{\mathrm{eff}}|$) are determined with unprecedented precision after combining the single and double-tag methods based on the decay process $\Lambda_{c}^{+}\to pK^{-}\pi^{+}$. Flat cross sections around $4.63~\mathrm{GeV}$ are obtained and no indication of the resonant structure $Y(4630)$, as reported by Belle, is found. In addition, no oscillatory behavior is discerned in the $|G_{\mathrm{eff}}|$ energy-dependence of $\Lambda_{c}^{+}$, in contrast to what is seen for the proton and neutron cases. Analyzing the cross section together with the polar-angle distribution of the $\Lambda_{c}^{+}$ baryon at each energy point, the moduli of electric and magnetic form factors ($|G_{E}|$ and $|G_{M}|$) are extracted and separated. For the first time, the energy-dependence of the form factor ratio $|G_{E}/G_{M}|$ is observed, which can be well described by an oscillatory function.

Phys. Rev. Lett.

The quantum entangled J/ψ → Σ+ ¯Σ− pairs from (1.0087 ± 0.0044) × 1010 J/ψ events taken by the BESIII detector are used to study the non-leptonic two-body weak decays Σ+ → nπ+ and ¯Σ− → ¯nπ−. The CP -odd weak decay parameters of the decays Σ+ → nπ+ (α+) and ¯Σ− → ¯nπ− (¯α−) are determined to be −0.0565±0.0047stat ±0.0022syst and 0.0481±0.0031stat ±0.0019syst, respectively. The decay parameter ¯α− is measured for the first time, and the accuracy of α+ is improved by a factor of four compared to the previous results. The simultaneously determined decay parameters allow the first precision CP symmetry test for any hyperon decay with a neutron in the final state with the measurement of ACP = (α+ + ¯α−)/(α+ − ¯α−) = −0.080 ± 0.052stat ± 0.028syst. Assuming CP conservation, the average decay parameter is determined as 〈α+〉 = (α+ − ¯α−)/2 = −0.0506 ± 0.0026stat ± 0.0019syst, while the ratios α+/α0 and ¯α−/¯α0 are −0.0490 ± 0.0032stat ± 0.0021syst and −0.0571±0.0053stat ±0.0032syst, where α0 and ¯α0 are the decay parameters of the decays Σ+ → pπ0 and ¯Σ− → ¯pπ0, respectively.

Phys.Atom.Nucl.

FASER is a new experiment at the CERN LHC which is located on the beam collision axis line-of-sight 480 m from the ATLAS collision point in unused service tunnel, TI12. The quite compact detector is designed to search for light and very weakly interacting new particles produced in the LHC collisions. The additional FASER$\nu$ emulsion sub-detector allows to detect and study neutrinos of all flavors produced at LHC. The detector has been successfully installed and is taking data during the LHC Run 3. Details on physics prospects, detector design, commissioning status and first recorded data will be given in this paper.

Phys.Atom.Nucl.

Recent results from the proton–proton collision data taken by the ATLAS experiment on the $B_{c}^{+}$ meson production and decays are presented. New results on the $B_{c}^{+}$ meson decays to $J/\psi D_{s}$ or $J/\psi D_{s}^{*}$ final states are included. This study is based on $pp$ collision data collected at $\sqrt{s}=13$ TeV during the LHC Run 2, corresponding to an integrated luminosity of 139 fb${}^{-1}$. The measurement of the ratios of the $B_{c}^{+}$ and $B^{+}$ meson differential production cross sections at $\sqrt{s}=8$ TeV with an integrated luminosity of 20.3 fb${}^{-1}$ is also discussed.

JACoW

The current status of the MSC230 superconducting cyclotron designed for biomedical research is presented. MSC230 is an isochronous four-sector compact cyclotron with a magnetic field in the center of 1.7 T. Acceleration is performed at the fourth harmonic mode of the accelerating radio-frequency (RF) system consisting of four cavities located in the cyclotron valleys. The accelerator will use an internal Penning type source with a hot cathode. Particular attention is paid to extraction, as it must have a high extraction efficiency.