The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.
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Journal of Physics G: Nuclear and Particle Physics publishes theoretical, experimental and computational research in nuclear and particle physics including all interface areas between these fields. The journal also publishes articles on nuclear and particle astrophysics.
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J Aalbers et al 2023 J. Phys. G: Nucl. Part. Phys. 50 013001
Juliette Alimena et al 2020 J. Phys. G: Nucl. Part. Phys. 47 090501
Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton–proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments—as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER—to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the high-luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity 'dark showers', highlighting opportunities for expanding the LHC reach for these signals.
Anne M Green and Bradley J Kavanagh 2021 J. Phys. G: Nucl. Part. Phys. 48 043001
The detection of gravitational waves from mergers of tens of Solar mass black hole binaries has led to a surge in interest in primordial black holes (PBHs) as a dark matter candidate. We aim to provide a (relatively) concise overview of the status of PBHs as a dark matter candidate, circa Summer 2020. First we review the formation of PBHs in the early Universe, focussing mainly on PBHs formed via the collapse of large density perturbations generated by inflation. Then we review the various current and future constraints on the present day abundance of PBHs. We conclude with a discussion of the key open questions in this field.
Jonathan L Feng et al 2023 J. Phys. G: Nucl. Part. Phys. 50 030501
High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.
S Adrián-Martínez et al 2016 J. Phys. G: Nucl. Part. Phys. 43 084001
The main objectives of the KM3NeT Collaboration are (i) the discovery and subsequent observation of high-energy neutrino sources in the Universe and (ii) the determination of the mass hierarchy of neutrinos. These objectives are strongly motivated by two recent important discoveries, namely: (1) the high-energy astrophysical neutrino signal reported by IceCube and (2) the sizable contribution of electron neutrinos to the third neutrino mass eigenstate as reported by Daya Bay, Reno and others. To meet these objectives, the KM3NeT Collaboration plans to build a new Research Infrastructure consisting of a network of deep-sea neutrino telescopes in the Mediterranean Sea. A phased and distributed implementation is pursued which maximises the access to regional funds, the availability of human resources and the synergistic opportunities for the Earth and sea sciences community. Three suitable deep-sea sites are selected, namely off-shore Toulon (France), Capo Passero (Sicily, Italy) and Pylos (Peloponnese, Greece). The infrastructure will consist of three so-called building blocks. A building block comprises 115 strings, each string comprises 18 optical modules and each optical module comprises 31 photo-multiplier tubes. Each building block thus constitutes a three-dimensional array of photo sensors that can be used to detect the Cherenkov light produced by relativistic particles emerging from neutrino interactions. Two building blocks will be sparsely configured to fully explore the IceCube signal with similar instrumented volume, different methodology, improved resolution and complementary field of view, including the galactic plane. One building block will be densely configured to precisely measure atmospheric neutrino oscillations.
(W-M Yao et al) 2006 J. Phys. G: Nucl. Part. Phys. 33 1
This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2633 new measurements from 689 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 110 reviews are many that are new or heavily revised including those on CKM quark-mixing matrix, Vud & Vus, Vcb & Vub, top quark, muon anomalous magnetic moment, extra dimensions, particle detectors, cosmic background radiation, dark matter, cosmological parameters, and big bang cosmology. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.
P Agostini et al 2021 J. Phys. G: Nucl. Part. Phys. 48 110501
The Large Hadron–Electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy-recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High-Luminosity Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electron–proton and proton–proton operations. This report represents an update to the LHeC's conceptual design report (CDR), published in 2012. It comprises new results on the parton structure of the proton and heavier nuclei, QCD dynamics, and electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics by extending the accessible kinematic range of lepton–nucleus scattering by several orders of magnitude. Due to its enhanced luminosity and large energy and the cleanliness of the final hadronic states, the LHeC has a strong Higgs physics programme and its own discovery potential for new physics. Building on the 2012 CDR, this report contains a detailed updated design for the energy-recovery electron linac (ERL), including a new lattice, magnet and superconducting radio-frequency technology, and further components. Challenges of energy recovery are described, and the lower-energy, high-current, three-turn ERL facility, PERLE at Orsay, is presented, which uses the LHeC characteristics serving as a development facility for the design and operation of the LHeC. An updated detector design is presented corresponding to the acceptance, resolution, and calibration goals that arise from the Higgs and parton-density-function physics programmes. This paper also presents novel results for the Future Circular Collider in electron–hadron (FCC-eh) mode, which utilises the same ERL technology to further extend the reach of DIS to even higher centre-of-mass energies.
K Nakamura and (Particle Data Group) 2010 J. Phys. G: Nucl. Part. Phys. 37 075021
This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2158 new measurements from 551 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on neutrino mass, mixing, and oscillations, QCD, top quark, CKM quark-mixing matrix, Vud & Vus, Vcb & Vub, fragmentation functions, particle detectors for accelerator and non-accelerator physics, magnetic monopoles, cosmological parameters, and big bang cosmology.
A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: pdg.lbl.gov.
H Schatz et al 2022 J. Phys. G: Nucl. Part. Phys. 49 110502
Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.
R Sahu et al 2024 J. Phys. G: Nucl. Part. Phys. 51 065104
Coherent elastic neutrino–nucleus scattering (CEνNS) is a neutral-current low-energy electro-weak reaction-channel detected recently by the COHERENT experiment at the Oak Ridge National Laboratory (ORNL), USA, in the Spallation Neutron Source facility. The extremely weak signal on the CsI detector of the first experiment and on the liquid Ar of the repeated COHERENT experiment is the energy-recoil due to the neutrino–nucleus interaction, where the nucleus is elastically scattered as a whole while simultaneously the neutrino goes out. Today, several promising nuclear detectors are on the way to be employed in designed and ongoing experiments. In our present work, we provide predictions for incoherent scattering cross sections of low-energy neutrinos on 98,100Mo isotopes obtained with the deformed shell model employed previously for similar predictions in other electroweak processes. We mention that, Mo detector medium has been used previously in the MOON and NEMO double beta decay experiments.
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Karim Ghorbani 2024 J. Phys. G: Nucl. Part. Phys. 51 065204
We consider a dark matter (DM) model with a singlet scalar, χ, as our DM candidate, which is secluded from the standard model (SM) and annihilates to the singlet scalar, ϕ, via a contact interaction. The singlet scalar, ϕ, has a leptophilic interaction with the SM leptons and may decay leptonically at tree level, and decays into a pair of photons at loop level. The focus of this work is to consider DM masses below 10 GeV. A viable secluded region is found in the parameter space after imposing the observed relic density. There is a one-loop interaction between scalar DM and the atomic electron in this model. We then apply the available direct detection bounds from Xenon10, Xenon1T and DarkSide on the DM-electron elastic scattering cross section. While the model can explain the muon anomalous magnetic moment, we apply bounds from current and future lepton collider experiments.
Vu Dong Tran et al 2024 J. Phys. G: Nucl. Part. Phys. 51 065105
Semi-empirical thermodynamic quantities (TQs) of 78 nuclei ranging from 43Sc to 243Pu have been systematically investigated in the temperature region below 1 MeV using the thermodynamic canonical ensemble. The latter is carried out by taking into account the experimental nuclear level density (NLD) data measured using the Oslo method for the low-excitation region below the neutron binding energy Bn combining with the back-shifted Fermi gas NLD model for the excitation energy from Bn to about 250 MeV. In particular, the uncertainty of the TQs propagating from the fluctuation of the experimental NLD data has been, for the first time, calculated. The results obtained indicate that the uncertainty of TQs due to the experimental NLD is incomparable with the changes caused by the nuclear structure effects. The free energy of even–even nuclei behaves differently from that of odd-A ones. The total energy in the low-temperature region below TE ≃ 0.4 − 0.6 MeV for medium-mass nuclei and TE ≃ 0.2 − 0.4 MeV for heavy-mass ones slowly varies. When temperature is from TE to 1 MeV, the total energy increases extremely faster than the increase of temperature, exhibiting the constant-temperature behavior. The entropy exhibits an abrupt change in their slope at TS ≃ 0.2 − 0.4 MeV in medium-mass nuclei and TS ≃ 0.5 − 0.6 MeV in heavy-mass ones. The existence of TE and TS has been interpreted due to the breaking of the first Cooper pair. Finally, the heat capacity shows a strongly pronounced S-shape in nuclei belonging to the rare-earth region. The temperatures defined at the center of the S − shaped heat capacities, which are known to closely relate to the critical temperature of the pairing phase transition TC, are quite close to those theoretically predicted, namely TC ≈ 0.5Δ − 0.6Δ with Δ = 12A−1/2 being the empirical pairing gap at zero temperature. The semi-empirical TQs obtained in the present work can be, therefore, a reliable data source to test and/or validate many nuclear thermodynamical models and to examine some nuclear structure properties such as pairing and deformation.
Dipali Basak et al 2024 J. Phys. G: Nucl. Part. Phys. 51 065107
The α-optical potential is one of the key input parameters used to measure the reaction rate of the (γ, α)-process using the Hauser-Feshbach statistical model and the principle of detailed balance. α-elastic scattering experiment on 113In p-nucleus was carried out in the energy range Elab = 26−32 MeV. The vacuum evaporation technique was used to prepare the 113In target (∼86 μg cm−2). An energy-dependent local optical potential parameters set was obtained by analysing the experimental elastic scattering angular distribution data. The local potential parameters are extrapolated for lower energies and are used to calculate the 113In(α, γ) reaction cross-section.
S Spor 2024 J. Phys. G: Nucl. Part. Phys. 51 065003
In a model-independent way, we explore the potential of photon-induced interactions with the process γ*γ* → ZZ to investigate CP-conserving and CP-violating dimension-six operators of Higgs-gauge boson couplings using the standard model effective field theory. The existence of anomalous Hγγ and HZZ couplings is discussed at 3 TeV compact linear collider (CLIC) and 10 TeV muon collider (MuC) with integrated luminosities of 5 and 10 ab−1, respectively. All signal and relevant background events are generated in MadGraph and passed through PYTHIA for parton showering and hadronization. The detector effects are evaluated using CLIC and MuC detector cards tuned in Delphes. We report the 95% confidence level limits on the Wilson coefficients , , , , , and and compare them with the experimental and phenomenological limits.
Murad Badshah et al 2024 J. Phys. G: Nucl. Part. Phys. 51 065109
In this study, we systematically investigate the dynamics of various hadrons namely π+, π−, K+, K−, p, , Λ, , Ξ− and produced in central Au–Au collisions. We analyze data of AGS and RHIC, which span a broad range of collision energies, ranging from = 1.9 to 200 GeV. To analyze the transverse momentum (pT) and transverse mass (mT) distributions, we employ a two-component standard distribution function, achieving a very good representation of the experimental data across these energy regimes. We extract key thermodynamic parameters, including the effective temperature T, the mean transverse momentum 〈pT〉, and the initial temperature Ti, and analyze their dependence on the values of collision energy and particle mass. Our findings reveal a distinct transition behaviour around . Below , the values of T, 〈pT〉, and Ti increase monotonically for all hadrons due to higher energy transfer into the system. Above this energy threshold, these extracted parameters plateau, suggesting that the additional energy is utilized as latent heat for phase transition rather than increasing the system's temperature. These observations delineate two distinct regions: a hadron-dominated region at lower energies and a parton-dominated region at higher energies, each potentially indicative of different phases of matter, with the latter possibly signalling the onset of a quark–gluon plasma. The study thus provides critical insights into the complex interplay of thermodynamics, phase transitions, and particle interactions in high-energy Au–Au collisions.
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P S B Dev et al 2024 J. Phys. G: Nucl. Part. Phys. 51 033001
Baryon number conservation is not guaranteed by any fundamental symmetry within the standard model, and therefore has been a subject of experimental and theoretical scrutiny for decades. So far, no evidence for baryon number violation has been observed. Large underground detectors have long been used for both neutrino detection and searches for baryon number violating processes. The next generation of large neutrino detectors will seek to improve upon the limits set by past and current experiments and will cover a range of lifetimes predicted by several Grand Unified Theories. In this White Paper, we summarize theoretical motivations and experimental aspects of searches for baryon number violation in neutrino experiments.
Elisabetta Bossio and Matteo Agostini 2024 J. Phys. G: Nucl. Part. Phys. 51 023001
Nuclear double-beta decays are a unique probe to search for new physics beyond the standard model. Hypothesized particles, non-standard interactions, or the violation of fundamental symmetries would affect the decay kinematics, creating detectable and characteristic experimental signatures. In particular, the energy distribution of the electrons emitted in the decay gives an insight into the decay mechanism and has been studied in several isotopes and experiments. No deviations from the prediction of the standard model have been reported yet. However, several new experiments are underway or in preparation and will soon increase the sensitivity of these beyond-the-standard-model physics searches, exploring uncharted parts of the parameter space. This review brings together phenomenological and experimental aspects related to new-physics searches in double-beta decay experiments, focusing on the testable models, the most-sensitive detection techniques, and the discovery opportunities of this field.
Hannah Elfner and Berndt Müller 2023 J. Phys. G: Nucl. Part. Phys. 50 103001
This article summarizes our present knowledge about nuclear matter at the highest energy densities and its formation in relativistic heavy ion collisions. We review what is known about the structure and properties of the quark-gluon plasma and survey the observables that are used to glean information about it from experimental data.
Sreelakshmi M and Akhilesh Ranjan 2023 J. Phys. G: Nucl. Part. Phys. 50 073001
In the past twenty years, hadron spectroscopy has made immense progress. Experimental facilities have observed different multiquark states during these years. There are different models and phenomenological potentials to study the nature of interquark interaction. In this work, we have reviewed different quark potentials and models used in hadron spectroscopy.
Alexander Huss et al 2023 J. Phys. G: Nucl. Part. Phys. 50 043001
Les Houches activities in 2021 were truncated due to the lack of an in-person component. However, given the rapid progress in the field and the restart of the LHC, we wanted to continue the bi-yearly tradition of updating the standard model precision wishlist. In this work we therefore review recent progress (since Les Houches 2019) in fixed-order computations for LHC applications. In addition, necessary ingredients for such calculations such as parton distribution functions, amplitudes, and subtraction methods are discussed. Finally, we indicate processes and missing higher-order corrections that are required to reach the theoretical accuracy that matches the anticipated experimental precision.
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Gao et al
A Bayesian neural network (BNN) is developed to predict the 1st excitation energy of odd-odd nuclei. Aside from the proton number and neutron number, we introduce two empirical physical quantities into the input layer. δ = [(-1)^N + (-1)^Z]/2 is introduced to distinguish even-even, odd-odd and odd-A nuclei; and the so-called Casten factor P =(v_p*v_n)/(v_p + v_n) is introduced to stand for collectivity. The BNN is trained with an experimental dataset of the 1st excitation energy for 434 odd-odd, 649 even-even and 1050 odd-A nuclei. After training, the BNN predicts the 1st excitation energy of odd-odd nuclei with a rms of $0.21$ MeV. Examples of Dy, Gd, Eu and Cs isotopes are also shown. The BNN results show moderate predictive ability, in comparison with results from the Projected Hartree-Fock method.
Kumar et al
In the present work, we investigate the bulk properties of nuclear matter
and neutron stars with the newly proposed relativistic interaction NL-RS which
provides an opportunity to readjust the coupling constants keeping in view the
properties of finite nuclei, nuclear matter, PREX-II results for neutron skin thickness in
208
Pb and astrophysical observations. The NL-RS model interaction has been proposed
by fitting the ground state properties (binding energies and charge radii) of finite
nuclei, bulk nuclear matter properties, and PREX-II results for neutron skin thickness
of 208 Pb. The relativistic interaction has been generated by including non-linear self-
interactions of σ and ωµ -mesons and mixed interactions of ωµ , and ρµ -meson up to
the quartic order. The proposed interaction harmonizes with the finite nuclei, bulk
nuclear matter, and neutron star properties. A covariance analysis is performed to
assess the statistical uncertainties on the model parameters and nuclear observables of
interest along with correlations amongst them. The equation of state (EoS) composed
of nucleons and leptons in β - β-equilibrium is computed with the proposed parameter
set and used to study the neutron star structure. The maximum mass of the neutron
star by employing the EoS computed with the NL-RS parameter set is 2.04±0.03
M⊙ and the radius of a canonical mass neutron star (R1.4 ) comes out to be equal to
13.06±0.16 Km. The value of dimensionless tidal deformability, for canonical mass, is
602.23±33.13 which satisfies the
Orce et al
New equations for the electric dipole polarizability αE1 of low-lying excited states in atomic nuclei — and the related (–2) moment of the total photo-absorption cross section, σ–2 — are inferred in terms of electric dipole and quadrupole matrix elements. These equations are valid for arbitrary angular momenta of the initial/ground and final/excited states and have been exploited in fully converged 1ω shell-model calculations of selected p- and sd-shell
nuclei that consider configuration mixing; advancing previous knowledge from 17O to 36Ar, where thousands of electric dipole matrix elements are computed from isovector excitations which include the giant dipole resonance region. Our results are in reasonable agreement with previous shell-model calculations and follow — except for 6,7 Li and 17,18 O — Migdal's global trend provided by the combination of the hydrodynamic model and second-order non-degenerate perturbation theory. Discrepancies in 6,7Li and 17O arise as a result of the presence of α-cluster configurations in odd-mass nuclei, whereas the disagreement in 18O comes from the mixing of intruder states, which is lacking in the shell-model interactions. More advanced ab initio calculations of the dipole polarizability for low-lying excited states covering all the isovector states within the giant dipole resonance region are missing and could be very valuable to benchmark the results presented here and shed further light on how atomic nuclei polarize away from the ground state
Palit et al
In this paper, a collider signature of a heavy Higgs boson at 14 TeV HL-LHC is studied, where
the heavy Higgs boson decays into a pair of standard model Higgs boson, which further decays to
bbZZ state and subsequently to bbℓ+ℓ−νℓνℓ final state. To study this, we consider singlet scalar
extension of the standard model and select the parameter space and mass of the heavy Higgs such
that it prefers a strong first order electroweak phase transition. The study is done following the
bbZZ analysis of CMS Collaboration and further using parameterized machine learning for final
discrimination which simplifies the training process along with an improved discrimination between
signal and background over the range of benchmark points. Despite the lower branching fraction,
this channel can be a potential probe of the electroweak phase transition with the data sets collected
by the CMS and ATLAS experiments at the 14 TeV HL-LHC with 3 ab−1 of integrated luminosity
and a production of resonant di-Higgs signal can be potentially discovered.
Loizos et al
We revisit the Standard Model fit to electroweak precision observables using the latest data and the Particle Data Group value of the mass of the W boson. This analysis is repeated for the value reported by CDF. The constraints on the parameter space for dark photons arising from these electroweak precision observables are then evaluated for both values of the W boson mass. We also extend previous work by placing the first electroweak precision observable constraints on the coupling of dark photons to the fermionic dark matter sector.
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Nico Orce and Cebo Ngwetsheni 2024 J. Phys. G: Nucl. Part. Phys.
New equations for the electric dipole polarizability αE1 of low-lying excited states in atomic nuclei — and the related (–2) moment of the total photo-absorption cross section, σ–2 — are inferred in terms of electric dipole and quadrupole matrix elements. These equations are valid for arbitrary angular momenta of the initial/ground and final/excited states and have been exploited in fully converged 1ω shell-model calculations of selected p- and sd-shell
nuclei that consider configuration mixing; advancing previous knowledge from 17O to 36Ar, where thousands of electric dipole matrix elements are computed from isovector excitations which include the giant dipole resonance region. Our results are in reasonable agreement with previous shell-model calculations and follow — except for 6,7 Li and 17,18 O — Migdal's global trend provided by the combination of the hydrodynamic model and second-order non-degenerate perturbation theory. Discrepancies in 6,7Li and 17O arise as a result of the presence of α-cluster configurations in odd-mass nuclei, whereas the disagreement in 18O comes from the mixing of intruder states, which is lacking in the shell-model interactions. More advanced ab initio calculations of the dipole polarizability for low-lying excited states covering all the isovector states within the giant dipole resonance region are missing and could be very valuable to benchmark the results presented here and shed further light on how atomic nuclei polarize away from the ground state
Bill Michael Loizos et al 2024 J. Phys. G: Nucl. Part. Phys.
We revisit the Standard Model fit to electroweak precision observables using the latest data and the Particle Data Group value of the mass of the W boson. This analysis is repeated for the value reported by CDF. The constraints on the parameter space for dark photons arising from these electroweak precision observables are then evaluated for both values of the W boson mass. We also extend previous work by placing the first electroweak precision observable constraints on the coupling of dark photons to the fermionic dark matter sector.
Daniel Siegmann et al 2024 J. Phys. G: Nucl. Part. Phys.
Sterile neutrinos in the keV mass range present a viable candidate for dark matter. They can be detected through single β decay, where they cause small spectral distortions. The Karlsruhe Tritium Neutrino (KATRIN) experiment aims to search for keV-scale sterile neutrinos with high sensitivity. To achieve this, the KATRIN beamline will be equipped with a novel multi-pixel silicon drift detector focal plane array named TRISTAN. In this study, we present the performance of a TRISTAN detector module, a component of the eventual 9-module system. Our investigation encompasses spectroscopic aspects such as noise performance, energy resolution, linearity, and stability.
Liam Hockley et al 2024 J. Phys. G: Nucl. Part. Phys. 51 065106
We present a lattice QCD analysis of the Δ-baryon spectrum, with the goal of finding the position of the 2s radial excitation of the Δ(1232) ground state. Using smeared three-quark operators in a correlation matrix analysis, we report masses for the ground, first and second excited states of the JP = 3/2+ spectrum across a broad range of . We identify the lowest lying state as being a 1s state, consistent with the well known Δ(1232). The first excitation is identified as a 2s state, but is found to have a mass of approximately 2.15 GeV on our ∼3 fm lattice, which does not appear to be associated with the Δ(1600) resonance in a significant manner. We also report on the spin-1/2 and odd-parity states accessible via our methods. The large excitation energies of the radial excitations provide a potential resolution to the long-standing missing baryon resonances problem.
R Sahu et al 2024 J. Phys. G: Nucl. Part. Phys. 51 065104
Coherent elastic neutrino–nucleus scattering (CEνNS) is a neutral-current low-energy electro-weak reaction-channel detected recently by the COHERENT experiment at the Oak Ridge National Laboratory (ORNL), USA, in the Spallation Neutron Source facility. The extremely weak signal on the CsI detector of the first experiment and on the liquid Ar of the repeated COHERENT experiment is the energy-recoil due to the neutrino–nucleus interaction, where the nucleus is elastically scattered as a whole while simultaneously the neutrino goes out. Today, several promising nuclear detectors are on the way to be employed in designed and ongoing experiments. In our present work, we provide predictions for incoherent scattering cross sections of low-energy neutrinos on 98,100Mo isotopes obtained with the deformed shell model employed previously for similar predictions in other electroweak processes. We mention that, Mo detector medium has been used previously in the MOON and NEMO double beta decay experiments.
Jack Holligan and Huey-Wen Lin 2024 J. Phys. G: Nucl. Part. Phys. 51 065101
We present a state-of-the-art calculation of the unpolarized pion valence-quark distribution in the framework of large-momentum effective theory (LaMET) with improved handling of systematic errors as well as two-loop perturbative matching. We use lattice ensembles generated by the MILC collaboration at lattice spacing a ≈ 0.09 fm, lattice volume 643 × 96, Nf = 2 + 1 + 1 flavors of highly-improved staggered quarks and a physical pion mass. The LaMET matrix elements are calculated with pions boosted to momentum Pz ≈ 1.72 GeV with high-statistics of O(106) measurements. We study the pion PDF in both hybrid-ratio and hybrid-regularization-independent momentum subtraction (hybrid-RI/MOM) schemes and also compare the systematic errors with and without the addition of leading-renormalon resummation (LRR) and renormalization-group resummation (RGR) in both the renormalization and lightcone matching. The final lightcone PDF results are presented in the modified minimal-subtraction scheme at renormalization scale μ = 2.0 GeV. We show that the x-dependent PDFs are compatible between the hybrid-ratio and hybrid-RI/MOM renormalization with the same improvements. We also show that systematics are greatly reduced by the simultaneous inclusion of RGR and LRR and that these methods are necessary if improved precision is to be reached with higher-order terms in renormalization and matching.
F Sgaramella et al 2024 J. Phys. G: Nucl. Part. Phys. 51 055103
In this paper we present the results of a new kaonic helium-4 measurement with a 1.37 g l−1 gaseous target by the SIDDHARTA-2 experiment at the DAΦNE collider. We measured, for the first time, the energies and yields of three transitions belonging to the M-series. Moreover, we improved by a factor about three, the statistical precision of the 2p level energy shift and width induced by the strong interaction, obtaining the most precise measurement for gaseous kaonic helium, and measured the yield of the Lα transition at the employed density, providing a new experimental input to investigate the density dependence of kaonic atoms transitions yield.
David d'Enterria and Dung Van Le 2024 J. Phys. G: Nucl. Part. Phys.
We perform an extensive survey of rare and exclusive few-body decays ---defined as those with branching fractions $\mathcal{B} \lesssim 10^{-5}$ and two or three final particles--- of the Higgs, Z, W bosons, and the top quark. Such rare decays can probe physics beyond the Standard Model (BSM), constitute a background for exotic decays into new BSM particles, and provide precise information on quantum chromodynamics factorization with small nonperturbative corrections. We tabulate the theoretical $\mathcal{B}$ values for almost 200 rare decay channels of the four heaviest elementary particles, indicating the current experimental limits in their observation. Among those, we have computed for the first time ultrarare Higgs boson decays into photons and/or neutrinos, H and Z radiative decays into leptonium states, radiative H and Z quark-flavour-changing decays, and semiexclusive top-quark decays into a quark plus a meson, while updating predictions for a few other rare H, Z, and top quark partial widths. The feasibility of measuring each of these unobserved decays is estimated for p-p collisions at the high-luminosity Large Hadron Collider (HL-LHC), and for $e^+e^-$ and p-p collisions at the future circular collider (FCC).
M Bashkanov et al 2024 J. Phys. G: Nucl. Part. Phys. 51 045106
In recent years, there has been tremendous progress in the investigation of bound systems of quarks with multiplicities beyond the more usual two- and three-quark systems. Experimental and theoretical progress has been made in the four-, five- and even six-quark sectors. In this paper, we review the possible lightest six-quark states using a simple ansatz based on SU(3) symmetry and evaluate the most promising decay branches. The work will be useful to help focus future experimental searches in this six-quark sector.
Ruben Gargiulo et al 2024 J. Phys. G: Nucl. Part. Phys. 51 045004
True muonium (TM) (μ+μ−) is the heaviest and smallest bound state not containing hadrons, after TM (τ+τ−) and mu-tauonium (μ±τ∓). One of the proposed methods to observe the spin 1 fundamental state of TM, which has the smallest lifetime among TM spin 1 states, was to build an e+e− collider with a large crossing angle (θ ∼ 30°) in order to provide TM with a large boost and detect its decay vertex in e+e−. The following paper will instead show that TM excited states can be observed in relatively large quantities ((10)/month) at a e+e− collider with standard crossing angle, after setting their center-of-mass energy to the TM mass (∼2mμ = 211.4 MeV).