Phys. Rev. Lett.

We report a search for neutrino oscillations to sterile neutrinos under a model with three active and one sterile neutrinos ($3+1$ model). This analysis uses the NOvA detectors exposed to the NuMI beam, running in neutrino mode. The data exposure, $13.6\times {10}^{20}$ protons on target, doubles that previously analyzed by NOvA, and the analysis is the first to use ${\nu }_{\mu }$ charged-current interactions in conjunction with neutral-current interactions. Neutrino samples in the near and far detectors are fitted simultaneously, enabling the search to be carried out over a $\mathrm{\Delta }{m}_{41}^2$ range extending 2 (3) orders of magnitude above (below) $1{\mathrm{eV}}^2$. NOvA finds no evidence for active-to-sterile neutrino oscillations under the $3+1$ model at 90% confidence level. New limits are reported in multiple regions of parameter space, excluding some regions currently allowed by IceCube at 90% confidence level. We additionally set the most stringent limits for anomalous ${\nu }_{\tau }$ appearance for $\mathrm{\Delta }{m}_{41}^2\le 3{\mathrm{eV}}^2$.

JINST

This paper introduces a novel track-length extension fittingalgorithm for measuring the kinetic energies of inelasticallyinteracting particles in liquid argon time projection chambers(LArTPCs). The algorithm finds the most probable offset in tracklength for a track-like object by comparing the measured ionizationdensity as a function of position with a theoretical prediction ofthe energy loss as a function of the energy, including models ofelectron recombination and detector response. The algorithm can beused to measure the energies of particles that interact before theystop, such as charged pions that are absorbed by argon nuclei. Thealgorithm's energy measurement resolutions and fractional biases arepresented as functions of particle kinetic energy and number oftrack hits using samples of stopping secondary charged pions in datacollected by the ProtoDUNE-SP detector, and also in a detailedsimulation. Additional studies describe the impact of the dE/dx model on energy measurement performance. The methoddescribed in this paper to characterize the energy measurementperformance can be repeated in any LArTPC experiment using stoppingsecondary charged pions.

arXiv

The nuGeN experiment searches for coherent elastic neutrino-nucleus scattering (CEvNS) at the Kalinin Nuclear Power Plant. A 1.41-kg high-purity low-threshold germanium detector surrounded by active and passive shielding is deployed at the minimal distance of 11.1 m allowed by the lifting mechanism from the center of reactor core, utilizing one of the highest antineutrino fluxes among the competing experiments. The direct comparison of the count rates obtained during reactor-ON and reactor-OFF periods with the energy threshold of 0.29~keV$_{ee}$ shows no statistically significant difference. New upper limits on the number of CEvNS events are evaluated on the basis of the residual ON$-$OFF count rate spectrum.

Moscow Univ.Phys.Bull.

Neutrino is considered as a superior astronomical messenger thanks to not being deflected or absorbed by interstellar medium. Detection of neutrinos from distant high-energy cosmic accelerators has been a long-standing problem emerged in the last quarter of 20th century. Only in 2013 was the diffuse cosmic neutrino flux discovered by the 1 km${}^{3}$—scale IceCube neutrino telescope at the South Pole. Nevertheless evidence for sources of cosmic neutrino remain weak up to the present day. The Baikal-GVD neutrino telescope being built in Lake Baikal is the largest detector of this kind in the Northern Hemisphere. Presently an instrumented volume of the detector is about 0.5 km${}^{3}$ which allows the telescope to start contributing to the cosmic neutrino origin quest. In this report we discuss the motivation present the status and main results of the Baikal-GVD experiment.

Moscow Univ. Phys. Bull.

FASER is a new experiment at CERN LHC located on the beam line-of-sight 480 m from the ATLAS collision point in the service tunnel TI12. A compact detector is designed to search for light and very weakly-interacting new particles which can be produced in LHC collisions. The additional FASER$\nu$ emulsion sub-detector allows detecting neutrinos of all flavours produced at LHC. The detector started taking data in 2022. The first physics results from one year of data-taking are presented. A search for dark photons decaying to an electron–positron pair found no events, yielding new constraints. A search for muon–neutrino charged-current interactions in a tungsten target at the front of the FASER experiment found 153 neutrino candidates with a negligible background. The reconstructed muons charge and momentum distribution imply the observation for the first time of both neutrinos and antineutrinos from LHC with energy above 200 GeV.

Moscow Univ. Phys. Bull.

The physics of neutrino oscillations has developed rapidly over the past few decades. Although there are still unmeasured parameters that determine this process. Measuring these parameters is the main goal of current and future projects in this area of particle physics. This review will discuss current neutrino accelerator experiments measuring three flavor neutrino oscillations (NOvA and T2K), and also briefly describe the prospects for future experiments (DUNE and Hyper-Kamiokande) and possible projects currently being considered.

JINST

The high-luminosity phase of LHC operations (HL-LHC), willfeature a large increase in simultaneous proton-proton interactionsper bunch crossing up to 200, compared with a typical levelingtarget of 64 in Run 3. Such an increase will create a verychallenging environment in which to perform charged particletrajectory reconstruction, a task crucial for the success of theATLAS physics program, and will exceed the capabilities of thecurrent ATLAS Inner Detector (ID). A new all-silicon Inner Tracker(ITk) will replace the current ID in time for the start of theHL-LHC. To ensure successful use of the ITk capabilities in Run 4and beyond, the ATLAS tracking software has been successfullyadapted to achieve state-of-the-art track reconstruction inchallenging high-luminosity conditions with the ITk detector. Thispaper presents the expected tracking performance of the ATLAS ITkbased on the latest available developments since the ITk technicaldesign reports.

JINST

DarkSide-20k (DS-20k) is a dark matter detection experimentunder construction at the Laboratori Nazionali del Gran Sasso (LNGS)in Italy. It utilises ∼ 100 t of low radioactivity argon from anunderground source (UAr) in its inner detector, with half serving astarget in a dual-phase time projection chamber (TPC). The UArcryogenics system must maintain stable thermodynamic conditionsthroughout the experiment's lifetime of over10 years. Continuous removal ofimpurities and radon from the UAr is essential for maximising signalyield and mitigating background. We are developing an efficient andpowerful cryogenics system with a gas purification loop with atarget circulation rate of1000 slpm. Central to itsdesign is a condenser operated with liquid nitrogen which is pairedwith a gas heat exchanger cascade, delivering a combined coolingpower of more than 8 kW. Here wepresent the design choices in view of the DS-20k requirements, inparticular the condenser's working principle and the coolingcontrol, and we show test results obtained with a dedicatedbenchmarking platform at CERN and LNGS. We find that the thermalefficiency of the recirculation loop, defined in terms of nitrogenconsumption per argon flow rate, is95 % and the pressure in the testcryostat can be maintained within±(0.1–0.2) mbar. Wefurther detail a 5-day cool-down procedure of the test cryostat,maintaining a cooling rate typically within-2 K/h, as required for theDS-20k inner detector. Additionally, we assess the circuit's flowresistance, and the heat transfer capabilities of two heat exchangergeometries for argon phase change, used to provide gas forrecirculation. We conclude by discussing how our findings influencethe finalisation of the system design, including necessarymodifications to meet requirements and ongoing testing activities.

Phys. Rev. Lett.

This Letter presents a search for highly ionizing magnetic monopoles in $262\mathrm{\mu }{\mathrm{b}}^{-1}$ of ultraperipheral $\mathrm{Pb}+\mathrm{Pb}$ collision data at $\sqrt{s_{\mathrm{NN}}}=5.36\mathrm{TeV}$ collected by the ATLAS detector at the LHC. A new methodology that exploits the properties of clusters of hits reconstructed in the innermost silicon detector layers is introduced to study highly ionizing particles in heavy-ion data. No significant excess above the background, which is estimated using a data-driven technique, is observed. Using a nonperturbative semiclassical model, upper limits at 95% confidence level are set on the cross section for pair production of monopoles with a single Dirac magnetic charge in the mass range of 20–150 GeV. Depending on the model, monopoles with a single Dirac magnetic charge and mass below 80–120 GeV are excluded.

JHEP

A search for the production of a Higgs boson and one or more charm quarks, in which the Higgs boson decays into a photon pair, is presented. This search uses proton-proton collision data with a centre-of-mass energy of $\sqrt{s}$ = 13 TeV and an integrated luminosity of 140 fb$^{−1}$ recorded by the ATLAS detector at the Large Hadron Collider. The analysis relies on the identification of charm-quark-containing jets, and adopts an approach based on Gaussian process regression to model the non-resonant di-photon background. The observed (expected, assuming the Standard Model signal) upper limit at the 95% confidence level on the cross-section for producing a Higgs boson and at least one charm-quark-containing jet that passes a fiducial selection is found to be 10.6 pb (8.8 pb). The observed (expected) measured cross-section for this process is 5.3 ± 3.2 pb (2.9 ± 3.1 pb).[graphic not available: see fulltext]

Phys.Rev.Lett.

The branching fraction ratios of ${\overline{B}}^0\to D^{+}{\tau }^{-}{\overline{\nu }}_{\tau }$ and ${\overline{B}}^0\to D^{*+}{\tau }^{-}{\overline{\nu }}_{\tau }$ decays are measured with respect to their muonic counterparts, using a data sample corresponding to an integrated luminosity of $2.0{\mathrm{fb}}^{-1}$ collected by the LHCb experiment in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$. The reconstructed final states are formed by combining $D^{+}$ mesons with ${\tau }^{-}\to {\mu }^{-}{\overline{\nu }}_{\mu }{\nu }_{\tau }$ candidates, where the $D^{+}$ is reconstructed via the $D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}$ decay. The results are $R(D^{+})=0.249\pm 0.043\pm 0.047$, $R(D^{*+})=0.402\pm 0.081\pm 0.085$, where the first uncertainties are statistical and the second systematic. The two measurements have a correlation coefficient of $-0.39$ and are compatible with the standard model.

Phys. Rev. C

In this study experiments were performed at bremsstrahlung end-point energies of 10–23 MeV with the beam from the MT-25 microtron (Joint Institute for Nuclear Research, Dubna) using the γ-activation technique. The experimental values of relative yields, cross sections per equivalent quantum and flux-averaged cross sections were compared with theoretical results obtained on the basis of TALYS-2.0 code with the standard parameters and the combined model of photonucleon reactions. Including isospin splitting in the combined model of photonucleon reactions allows describing experimental data on reactions with proton escape in the energy range from 15 to 23 MeV. Therefore, taking into account isospin splitting is necessary for a correct description of the decay of the giant dipole resonance.

JHEP

A search is presented for the resonant production of a pair of standard model-like Higgs bosons using data from proton-proton collisions at a centre-of-mass energy of 13 TeV, collected by the CMS experiment at the CERN LHC in 2016–2018, corresponding to an integrated luminosity of 138 fb$^{−1}$. The final state consists of two b quark-antiquark pairs. The search is conducted in the region of phase space where at least one of the pairs is highly Lorentz-boosted and is reconstructed as a single large-area jet. The other pair may be either similarly merged or resolved, the latter reconstructed using two b-tagged jets. The data are found to be consistent with standard model processes and are interpreted as 95% confidence level upper limits on the product of the cross sections and the branching fractions of the spin-0 radion and the spin-2 bulk graviton that arise in warped extradimensional models. The limits set are in the range 9.74–0.29 fb and 4.94–0.19 fb for a narrow radion and a graviton, respectively, with masses between 1 and 3 TeV. For a radion and for a bulk graviton with widths 10% of their masses, the limits are in the range 12.5–0.35 fb and 8.23–0.23 fb, respectively, for the same masses. These limits result in the exclusion of a narrow-width graviton with a mass below 1.2 TeV, and of narrow and 10%-width radions with masses below 2.6, and 2.9 TeV, respectively.[graphic not available: see fulltext]

Eur. Phys. J. C

A search for a light charged Higgs boson produced in decays of the top quark, $t \rightarrow H^{\pm } b$ with $H^{\pm } \rightarrow cs$, is presented. This search targets the production of top-quark pairs $t\bar{t} \rightarrow Wb H^{\pm } b$, with $W \rightarrow \ell \nu$ ($\ell = e, \mu$), resulting in a lepton-plus-jets final state characterised by an isolated electron or muon and at least four jets. The search exploits b-quark and c-quark identification techniques as well as multivariate methods to suppress the dominant $t\bar{t}$ background. The data analysed correspond to $140\hbox { fb}^{-1}$ of $pp$ collisions at $\sqrt{s} = 13\hbox { TeV}$ recorded with the ATLAS detector at the LHC between 2015 and 2018. Observed (expected) 95% confidence-level upper limits on the branching fraction $\mathscr {B}(t\rightarrow H^{\pm } b)$, assuming $\mathscr {B}(t\rightarrow Wb) + \mathscr {B}(t \rightarrow H^{\pm } (\rightarrow cs)b)=1.0$, are set between 0.066% (0.077\) and 3.6% (2.3\) for a charged Higgs boson with a mass between 60 and 168 GeV.

JHEP

A search for long-lived heavy neutral leptons (HNLs) using proton-proton collision data corresponding to an integrated luminosity of 138 fb$^{−1}$ collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC is presented. Events are selected with a charged lepton originating from the primary vertex associated with the proton-proton interaction, as well as a second charged lepton and a hadronic jet associated with a secondary vertex that corresponds to the semileptonic decay of a long-lived HNL. No excess of events above the standard model expectation is observed. Exclusion limits at 95% confidence level are evaluated for HNLs that mix with electron and/or muon neutrinos. Limits are presented in the mass range of 1–16.5 GeV, with excluded square mixing parameter values reaching as low as 2 × 10$^{−7}$. For masses above 11 GeV, the presented limits exceed all previous results in the semileptonic decay channel, and for some of the considered scenarios are the strongest to date.[graphic not available: see fulltext]

JINST

Measuring observables to constrain models using maximum-likelihood estimation is fundamental to many physics experiments.Wilks' theorem provides a simple way to construct confidence intervals on model parameters, but it only applies under certain conditions. These conditions, such as nested hypotheses and unbounded parameters, are often violated in neutrino oscillation measurements and other experimental scenarios. Monte Carlo methods can address these issues, albeit at increased computational cost. In the presence of nuisance parameters, however, the best way to implement a Monte Carlo method is ambiguous.This paper documents the method selected by the NOvA experiment, the profile construction. It presents the toy studies that informed the choice of method, details of its implementation, and tests performed to validate it. It also includes some practical considerations which may be of use to others choosing to use the profile construction.

Instrum. Exp. Tech.

The Baikal-GVD deep-sea Cherenkov detector, whose deployment in Lake Baikal has been ongoing since 2016, currently represents the largest neutrino telescope in the Northern Hemisphere. The principle of the telescope’s operation is based on the registration of Cherenkov radiation produced by the products of neutrino interaction in the aquatic environment using the spatial structure of photodetectors. Laser light sources specially designed for the Baikal project are used to calibrate and measure the characteristics of the telescope’s detecting system. The article describes the design and features of the functioning of calibration laser sources, presents the results of their operation as part of the telescope, and discusses issues of further development of the laser-calibration system.

Rept. Prog. Phys.

A search for light long-lived particles (LLPs) decaying to displaced jets is presented, using a data sample of proton–proton collisions at a center-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 34.7 fb$^{−1}$, collected with the CMS detector at the CERN LHC in 2022. Novel trigger, reconstruction, and machine-learning techniques were developed for and employed in this search. After all selections, the observations are consistent with the background predictions. Limits are presented on the branching fraction of the Higgs boson to LLPs that subsequently decay to quark pairs or tau lepton pairs. An improvement by up to a factor of 10 is achieved over previous limits for models with LLP masses smaller than 60 GeV and proper decay lengths smaller than 1 m. The first constraints are placed on the fraternal twin Higgs (FTH) and folded supersymmetry (FSUSY) models, where the lower bounds on the top quark partner mass reach up to 350 GeV for the FTH model and 250 GeV for the FSUSY model.

Bull. Lebedev Phys. Inst.

The νGeN experimental setup, with a low-threshold germanium spectrometer as its basic element, is deployed at Unit 3 of the Kalinin Nuclear Power Plant, at a distance of 11 m from the centre of the reactor core. The experiment aims to observe coherent elastic scattering of neutrinos off germanium nuclei, as well as to search for antineutrino electromagnetic properties. This paper presents an estimate of νGeN sensitivity to the antineutrino magnetic moment based on the 98 kg day reactor-OFF dataset. The expected limit is 5.3 × 10$^{−11}$ μ$_{B}$ at the 90% confidence level for the exposition of 198 kg day with the reactor ON and 98 kg day with the reactor OFF. The projected sensitivity for the 1100 kg day reactor-ON dataset is 2.6 × 10$^{−11}$ μ$_{B}$.

Eur. Phys. J. C

This paper reports the measurement of Higgs boson production in association with a $t\bar{t}$ pair in the $H\rightarrow b\bar{b}$ decay channel. The analysis uses 140 fb$^{-1}$ of 13 TeV proton$-$proton collision data collected with the ATLAS detector at the Large Hadron Collider. The final states with one or two electrons or muons are employed. An excess of events over the expected background is found with an observed (expected) significance of 4.6 (5.4) standard deviations. The $t\bar{t}H$ cross-section is $\sigma_{t\bar{t}H} = 411^{+101}_{-92}$ fb $= 411 \pm 54( \text{stat.}) ^{+85}_{-75}( \text{syst.})$ fb for a Higgs boson mass of 125.09 GeV, consistent with the prediction of the Standard Model of $507^{+35}_{-50}$ fb. The cross-section is also measured differentially in bins of the Higgs boson transverse momentum within the simplified template cross-section framework.

JHEP

A search for $T$ and $Y$ vector-like quarks produced in proton-proton collisions at a centre-of-mass energy of $13\,\text{TeV}$ and decaying into $Wb$ in the fully hadronic final state is presented. The search uses 139 fb$^{-1}$ of data collected by the ATLAS detector at the LHC from 2015 to 2018. The final state is characterised by a hadronically decaying $W$ boson with large Lorentz boost and a $b$-tagged jet, which are used to reconstruct the invariant mass of the vector-like quark candidate. The main background is QCD multijet production, which is estimated using a data-driven method. Upon finding no significant excess in data, mass limits at 95% confidence level are obtained as a function of the global coupling parameter, $\kappa$. The observed lower limits on the masses of $Y$ quarks with $\kappa = 0.5$ and $\kappa = 0.7$ are 2.0 TeV and 2.4 TeV, respectively. For $T$ quarks, the observed mass limits are 1.4 TeV for $\kappa = 0.5$ and 1.9 TeV for $\kappa = 0.7$.

Phys. Rev. D

A search for the production of three Higgs bosons ($HHH$) in the $b\overline{b}b\overline{b}b\overline{b}$ final state is presented. The search uses $126{\mathrm{fb}}^{-1}$ of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$ collected with the ATLAS detector at the Large Hadron Collider. The analysis targets both nonresonant and resonant production of $HHH$. The resonant interpretations primarily consider a cascade decay topology of $X\to SH\to HHH$ with masses of the new scalars $X$ and $S$ up to 1.5 and 1 TeV, respectively. In addition to scenarios where $S$ is off-shell, the nonresonant interpretation includes a search for Standard Model $HHH$ production, with limits on the trilinear and quartic Higgs self-coupling set. No evidence for $HHH$ production is observed. An upper limit of 59 fb is set, at the 95% confidence level, on the cross section for Standard Model $HHH$ production.

Phys. Rev. D

Using $(2712\pm 14)\times {10}^6$ $\psi (2S)$ events collected with the BESIII detector at the BEPCII collider, we search for the decays ${\eta }_c(2S)\to \omega \omega$ and ${\eta }_c(2S)\to \omega \varphi$ via the process $\psi (2S)\to \gamma {\eta }_c(2S)$. No statistically significant signals are observed. The upper limits of their product branching fractions at the 90% confidence level are determined to be $\mathcal{B}(\psi (2S)\to \gamma {\eta }_c(2S),{\eta }_c(2S)\to \omega \omega )<1.04\times {10}^{-6}$ and $\mathcal{B}(\psi (2S)\to \gamma {\eta }_c(2S),{\eta }_c(2S)\to \omega \varphi )<1.85\times {10}^{-7}$, respectively. We also update the branching fractions of ${\chi }_{cJ}\to \omega \omega$ and ${\chi }_{cJ}\to \omega \varphi$ via the $\psi (2S)\to \gamma {\chi }_{cJ}$ transition. Their branching fractions are determined to be $\mathcal{B}({\chi }_{c0}\to \omega \omega )=(10.66\pm 0.11\pm 0.57)\times {10}^{-4}$, $\mathcal{B}({\chi }_{c1}\to \omega \omega )=(6.43\pm 0.07\pm 0.31)\times {10}^{-4}$, $\mathcal{B}({\chi }_{c2}\to \omega \omega )=(8.75\pm 0.08\pm 0.42)\times {10}^{-4}$, $\mathcal{B}({\chi }_{c0}\to \omega \varphi )=(1.18\pm 0.03\pm 0.07)\times {10}^{-4}$, $\mathcal{B}({\chi }_{c1}\to \omega \varphi )=(2.04\pm 0.15\pm 0.11)\times {10}^{-5}$, and $\mathcal{B}({\chi }_{c2}\to \omega \varphi )=(9.58\pm 1.07\pm 0.76)\times {10}^{-6}$, where the first uncertainties are statistical and the second are systematic.

Phys. Rev. D

Using $(2712.4\pm 14.3)\times {10}^6\psi (3686)$ events collected by the BESIII detector operating at the BEPCII collider, we present the first observations of the decays ${\chi }_{cJ}(J=0,1,2)\to p\overline{p}\eta {\pi }^0$. Their decay branching fractions are determined to be $\mathcal{B}({\chi }_{c0}\to p\overline{p}\eta {\pi }^0)=(2.42\pm 0.07\pm 0.19)\times {10}^{-4}$, $\mathcal{B}({\chi }_{c1}\to p\overline{p}\eta {\pi }^0)=(1.95\pm 0.05\pm 0.12)\times {10}^{-4}$, and $\mathcal{B}({\chi }_{c2}\to p\overline{p}\eta {\pi }^0)=(1.33\pm 0.05\pm 0.08)\times {10}^{-4}$, where the first uncertainties are statistical and the second systematic.

Phys. Rev. D

Using a sample of $(2712\pm 14)\times {10}^6\psi (3686)$ events collected with the BESIII detector, we perform partial wave analyses of the decays $\psi (3686)\to p\overline{p}{\pi }^0$ and $\psi (3686)\to p\overline{p}\eta$. The branching fractions of $\psi (3686)\to p\overline{p}{\pi }^0$ and $\psi (3686)\to p\overline{p}\eta$ are determined to be $(133.9\pm 11.2\pm 2.3)\times {10}^{-6}$ or $(183.7\pm 13.7\pm 3.2)\times {10}^{-6}$ and $(61.5\pm 6.5\pm 1.1)\times {10}^{-6}$ or $(84.4\pm 6.9\pm 1.4)\times {10}^{-6}$, respectively, where the two solutions are caused by an ambiguous phase angle between resonant and continuum processes. Several well-established $N^{*}$ states are observed in the $p{\pi }^0$ and $p\eta$ systems, and the corresponding branching fractions are measured. The ratio of decay widths ${\mathrm{\Gamma }}_{N(1535)\to N\eta }/{\mathrm{\Gamma }}_{N(1535)\to N\pi }$ is determined to be $0.99\pm 0.05\pm 0.19$.