Indirect Constraints Research Articles

Large-scale basement mobilization endows the giant Carlin-type gold mineralization in the Youjiang Basin, South China: Insights from mercury isotopes

The metal source and genesis of hydrothermal mercury-rich gold metallogenic systems occurring far away from active continental margins remain puzzling. The Youjiang Basin of South China, where exists numerous Carlin-type gold deposits and some synmineralization hidden intrusions, is a natural laboratory to address this issue due to it was up to 1000 km inward from the active continental margins of South China when mineralization. Here, we use mass-independent fractionation of mercury isotope ratios (reported as ∆199Hg), which is predominantly generated during Hg photochemical reactions on Earth’s surface and has superiority of isotopic inheritance during hydrothermal processes, to address the metal source of the Youjiang Carlin-type gold deposits. Ore-associated sulfides from seven representative deposits display negative to near-zero ∆199Hg values (−0.29‰ to 0.04‰), which fall in between that of the regional Precambrian basement rocks (−0.21‰ to 0.06‰) and deep magmatic-hydrothermal systems (∼0‰), suggesting a binary mixing of Hg from these two sources. An isotope mixing model and mass balance calculations demonstrate that ∼1000 km3 of the basement rocks, which contributed to 86% of Hg budget, were leached and remobilized by magmatic-hydrothermal fluids and deep-circulating crustal fluids to endow the gold reserves of these deposits. Given that traditional S, Pb, C, and O isotopic data yielded indirect and ambiguous constraints on metal source due to their complex evolution processes and isotope fractionation during the fluids ascended. Our results, therefore, highlight the great advantage of using Hg isotope as a new tracer to understand metal sources of hydrothermal deposits.

Indirect constraints on lepton-flavor-violating quarkonium decays

Within an effective-field-theory framework, we present a model-independent analysis of the potential of discovering new physics by searching for lepton flavor violation in heavy quarkonium decays and, more in general, we study the phenomenology of lepton-flavor-violating (LFV) 2 quark-2 lepton ($2q2\ensuremath{\ell}$) operators with two charm or bottom fields. We compute the constraints from LFV muon and tau decays on the new-physics operators that can induce LFV processes involving $c\overline{c}$ and $b\overline{b}$ systems, thus providing a comprehensive list of indirect upper limits on processes such as $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\ell}{\ensuremath{\ell}}^{\ensuremath{'}}$, $\mathrm{\ensuremath{\Upsilon}}(nS)\ensuremath{\rightarrow}\ensuremath{\ell}{\ensuremath{\ell}}^{\ensuremath{'}}$, $\mathrm{\ensuremath{\Upsilon}}(nS)\ensuremath{\rightarrow}\ensuremath{\ell}{\ensuremath{\ell}}^{\ensuremath{'}}\ensuremath{\gamma}$ etc., which can be sought at BESIII, Belle II, and the proposed super tau-charm factory. We show that such indirect constraints are so stringent that they prevent the detection of quarkonium decays into $e\ensuremath{\mu}$. In the case of decays of quarkonia into $\ensuremath{\ell}\ensuremath{\tau}$ ($\ensuremath{\ell}=e$, $\ensuremath{\mu}$), we find that an improvement by 2-3 orders of magnitude on the current sensitivities is in general required in order to discover or further constrain new physics. However, we show that cancellations among different contributions to the LFV tau decay rates are possible, such that $\mathrm{\ensuremath{\Upsilon}}(nS)\ensuremath{\rightarrow}\ensuremath{\ell}\ensuremath{\tau}$ can saturate the present experimental bounds. We also find that, interestingly, searches for LFV $Z$ decays, $Z\ensuremath{\rightarrow}\ensuremath{\ell}\ensuremath{\tau}$, at future ${e}^{+}{e}^{\ensuremath{-}}$ colliders are complementary probes of $2q2\ensuremath{\ell}$ operators with third generation quarks.

Resonant production of light sterile neutrinos in compact binary merger remnants

The existence of eV-mass sterile neutrinos is not ruled out because of persistent experimental anomalies. Upcoming multi-messenger detections of neutron-star merger remnants could provide indirect constraints on the existence of these particles. We explore the active-sterile flavor conversion phenomenology in a two-flavor scenario (1 active + 1 sterile species) as a function of the sterile neutrino mixing parameters, neutrino emission angle from the accretion torus, and temporal evolution of the merger remnant. The torus geometry and the neutron richness of the remnant are responsible for the occurrence of multiple resonant active-sterile conversions. The number of resonances strongly depends on the neutrino emission direction above or inside the remnant torus and leads to large production of sterile neutrinos (and no antineutrinos) in the proximity of the polar axis as well as more sterile antineutrinos than neutrinos in the equatorial region. As the black hole torus evolves in time, the shallower baryon density is responsible for more adiabatic flavor conversion, leading to larger regions of the mass-mixing parameter space being affected by flavor mixing. Our findings imply that the production of sterile states could have indirect implications on the disk cooling rate, its outflows, and related electromagnetic observables which remain to be assessed.

Higgs-boson visible and invisible constraints on hidden sectors

We investigate the impact of interactions between hidden sectors and the discovered Higgs boson h_{125}, allowing for additional invisible decay channels of h_{125}. We perform chi ^2-fits to the measurements of the Higgs-boson cross sections as a function of the invisible branching ratio and different combinations of coupling modifiers, where the latter quantify modifications of the couplings of h_{125} compared to the predictions of the Standard Model. We present generic results in terms of exclusion limits on the coupling modifiers and the invisible branching ratio of h_{125}. Additionally, we apply our results to a variety of concrete model realizations containing a hidden sector: dark matter within Higgs- and singlet-portal scenarios, models featuring (pseudo) Nambu–Goldstone bosons and two Higgs doublet extensions. One of the main conclusions of our work is that in a wide class of models the indirect constraints resulting from the measurements of the cross sections of h_{125} provide substantially stronger constraints on the invisible Higgs-boson branching ratio compared to the direct limits obtained from searches for the invisible decay of h_{125}. However, we demonstrate that the presence of an invisible decay mode of h_{125} can also open up parameter space regions which otherwise would be excluded as a result of the indirect constraints. As a byproduct of our analysis, we show that in light of the new results from the LZ collaboration a fermionic DM candidate within the simplest Higgs-portal scenario is ruled out under standard assumptions.

Resolving muon g-2 anomaly with partial compositeness

We consider the scenario of composite Higgs with partial compositeness to address the muon g-2 anomaly. We show that this anomaly is resolved by one-loop correction due to composite muon partners with mass scale of order TeVs and large Yukawa coupling to composite Higgs, which is different from interpretations of vectorlike lepton models. We present parameter space by imposing indirect constraints from precise measurements on Higgs, Z and oblique electroweak parameters. We analyze direct constraints in light of both Drell–Yan and Higgs-associated productions of the composite muon partners at high-luminosity LHC. It turns out that the parameter regions with the lighter composite muon mass below sim 325 GeV can be excluded at 2sigma order by the Drell–Yan processes.

Anti-weaponization of Outer Space for Maintaining Long-term Sustainability of Outer Space Activities

Space weaponization should be prevented because of its detrimental effects on the long-term sustainability of outer space activities (LTSOSA). International law that currently governs weaponization in outer space should be implemented, and international rules that pertain to the LTSOSA should impose direct and indirect soft-law constraints on space weaponization. Nevertheless, the direct and indirect roles of international law in inhibiting space weaponization are limited, and a legal lacuna still exists in the governance of conventional weapons in the Earth's orbit. Independent and more focused discussions on specific issues related to space security are recommended given that the disagreement on related issues has prevented real progress from being made during multilateral discussions addressing the space technologies that could be used in a hostile manner. The integration of some norms of responsible space activity into the new LTSOSA Guidelines discussed under the auspices of the United Nations Committee on the Peaceful Uses of Outer Space is also recommended, along with an ongoing strong political constraint on the deployment and testing of dedicated space weapons in outer space through the adoption of the United Nations General Assembly resolutions and international condemnation. The latter is a good alternative under the current circumstances to preserve the LTSOSA by working against the weaponization of outer space.

Hematite geochronology reveals a tectonic trigger for iron ore mineralization during Nuna breakup

Abstract Hematite and goethite deposits hosted in banded iron formations (BIFs) in the Pilbara craton (Western Australia) represent one of Earth's most significant Fe reserves; however, the timing and tectonic triggers underpinning deposit genesis remain contentious. Uncertainty in ore genesis stems from a lack of direct age measurements, which could aid in correlating periods of BIF mineralization with tectono-thermal events observed elsewhere. Archean–Paleoproterozoic BIFs in the Hamersley Province host extensive martite–microplaty hematite orebodies that formed at 2.2–2.0 Ga, based on indirect constraints. In contrast, combined hematite in situ U-Pb geochronology and (U-Th)/He thermochronology demonstrate that martite–microplaty hematite ores in the Chichester Range crystallized ca. 1.26–1.22 Ga and underwent cratonic denudation between ca. 0.57 and 0.38 Ga. Nanoscale imaging of dated hematite indicates that U-Th-Pb is lattice bound and not hosted in inclusions. New U-Pb hematite ages overlap with other mineral ages reported at the margins of the Pilbara and Yilgarn cratons (1.3–1.1 Ga), where mineral formation was driven by plate reorganization following breakup of the Nuna supercontinent. This age correlation suggests that a combination of increased orogenic (+diagenetic) and heat (+fluid) generative processes resulting from supercontinent reconfiguration was a key trigger for iron ore formation in the Pilbara craton.

First Indirect Detection Constraints on Axions in the Solar Basin.

Axions with masses of order keV can be produced in great abundance within the Solar core. The majority of Sun-produced axions escape to infinity, but a small fraction of the flux is produced with speeds below the escape velocity. Over time, this process populates a basin of slow-moving axions trapped on bound orbits. These axions can decay to two photons, yielding an observable signature. We place the first limits on this solar basin of axions using recent quiescent solar observations made by the NuSTAR x-ray telescope. We compare three different methodologies for setting constraints, and obtain world-leading limits for axions with masses between 5 and 30keV, in some cases improving on stellar cooling bounds by more than an order of magnitude in coupling.

Minimal Realization of Light Thermal Dark Matter.

We propose a minimal UV-complete model for kinematically forbidden dark matter (DM) leading to a sub-GeV thermal relic. Our crucial realization is that the two-Higgs-doublet model can provide a light mediator through which the DM can annihilate into standard model leptons, avoiding indirect detection constraints. The DM mass is predicted to be very close to the mass of the leptons, which can potentially be identified from DM annihilation into gamma rays. Because of the sizable couplings to muons required to reproduce the DM relic abundance, this framework naturally favors a resolution to the (g-2)_{μ} anomaly. Furthermore, by embedding this setup to the Zee model, we show that the phenomenon of neutrino oscillations is inherently connected to the observed relic abundance of DM. All new physics involved in our framework lies at or below the electroweak scale, making it testable at upcoming colliders, beam-dump experiments, and future sub-GeV gamma-ray telescopes.

Can local environmental constraints improve enterprise's green innovation quality? Evidence from Chinese-listed firms.

The target responsibility system of environmental protection is one of the vital channels to achieve a win-win situation for both economic development and environmental protection. Comprehensively investigating how local environmental target constraints drive enterprises to improve their green innovation quality is of enormous theoretical and practical significance for optimizing the implementation effect of environmental target constraints policies and boosting enterprises' green and high-quality development. We empirically examine the mechanism of the impact of the intensity of different types of local environmental target constraints on the quality of corporate green innovation and the nonlinear relationship between them through innovatively constructing indicators of local environmental target constraint intensity and utilizing the knowledge width of green patents of listed companies as a proxy variable for enterprise green innovation quality. First, the strength of indirect environmental target constraints has a significant positive effect on the quality of green innovation, but further nonlinear characteristics reveal a significant inverse U-shaped relationship between them. Second, indirect environmental target constraint intensity has an inverted U-shaped trend in increasing the intensity of environmental regulation and influencing the digitalization of enterprises, which in turn forms an inverted U-shaped relationship with the quality of green innovation. Third, indirect environmental target constraint intensity works better in areas with policies prioritizing city over province, with mayors less than 57years old, and for enterprises in technology-intensive industries.

Measuring single-top-associated Higgs production at the HL-LHC

Precision measurements of top-associated Higgs production are an important ingredient to unravel the CP nature of the Higgs boson. In this work, we constraint the CP nature of the top-Yukawa coupling taking into account all relevant inclusive and differential Higgs boson measurements. Based upon this fit, we show that it is crucial to disentangle single- and di-top-associated Higgs production for tightening indirect constraints on a CP-odd top-Yukawa coupling in the future. In this context, we propose an analysis strategy for measuring tH production at the HL-LHC without relying on assumptions about the Higgs CP character.

Correlating gravitational wave and gamma-ray signals from primordial black holes

Asteroid-mass primordial black holes (PBH) can explain the observed dark matter abundance while being consistent with the current indirect detection constraints. These PBH can produce gamma-ray signals from Hawking radiation that are within the sensitivity of future measurements by the AMEGO and e-ASTROGAM experiments. PBH which give rise to such observable gamma-ray signals have a cosmic origin from large primordial curvature fluctuations. There must then be a companion, stochastic gravitational wave (GW) background produced by the same curvature fluctuations. We demonstrate that the resulting GW signals will be well within the sensitivity of future detectors such as LISA, DECIGO, BBO, and the Einstein Telescope. The multi-messenger signal from the observed gamma-rays and GW will allow a precise measurement of the primordial curvature perturbation that produces the PBH. Indeed, we argue that the resulting correlation between the two types of observations can provide a smoking-gun signal of PBH.

Signals for vector-like leptons in an S_3-symmetric 2HDM at ILC

In this work, we explore the signals of an S_3-symmetric two Higgs doublet model with two generations of vector-like leptons (VLLs) at the proposed International Linear Collider (ILC). The lightest neutral component of the VLL in this model provides a viable dark matter (DM) candidate satisfying the current relic density data as well as circumventing all direct and indirect DM search constraints. Some representative benchmark points have been selected with low, medium and high DM masses, satisfying all theoretical and experimental constraints of the model and constraints coming from the DM sector. The VLLs (both neutral and charged) will be produced in pair leading to multi-lepton and multi-jet final states. We show that the ILC will prove to be a much more efficient and useful machine to hunt for such signals compared to LHC. Using traditional cut-based analysis as well as sophisticated multivariate analysis, we perform a detailed analysis of some promising channels containing mono-lepton plus di-jet, di-lepton, four-lepton and four jets along with missing transverse energy in the final state at 1 TeV ILC.

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo’s third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours–months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets.

SRG/ART-XC, Swift, NICER, and NuSTAR study of different states of the transient X-ray pulsar MAXI J0903–531

The results of the broadband spectral and timing study of the recently discovered transient X-ray pulsar MAXI J0903–531 in a wide range of luminosities that differ by a factor of ~30 are reported. The observed X-ray spectrum in both states can be described as a classical pulsar-like spectrum consisting of a power law with a high-energy cutoff. We argue that the absence of the spectrum transformation to the two-hump structure that is expected at low fluxes indicates that the magnetic field of the neutron star is relatively weak below (2–3) × 1012 G. This estimate is consistent with other indirect constraints and non-detection of any absorption features that might be interpreted as a cyclotron absorption line. The timing analysis of the NuSTAR data revealed only slight variations of a single-peaked pulse profile of the source as a function of the energy band and mass accretion rate. In both intensity states, the pulsed fraction increases from 40% to roughly 80% with the energy. Finally, we were also able to obtain the orbital solution for the binary system using data from the Fermi/GBM, NICER, and NuSTAR instruments.

Improved Indirect Limits on Muon Electric Dipole Moment.

Given current discrepancy in muon g-2 and future dedicated efforts to measure muon electric dipole moment (EDM) d_{μ}, we assess the indirect constraints imposed on d_{μ} by the EDM measurements performed with heavy atoms and molecules. We notice that the dominant muon EDM effect arises via the muon-loop induced "light-by-light" CP-odd amplitude ∝BE^{3}, and in the vicinity of a large nucleus the corresponding parameter of expansion can be significant, eE_{nucl}/m_{μ}^{2}∼0.04. We compute the d_{μ}-induced Schiff moment of the ^{199}Hg nucleus, and the linear combination of d_{e} and semileptonic C_{S} operator (dominant in this case) that determine the CP-odd effects in the ThO molecule. The results, d_{μ}(^{199}Hg)<6×10^{-20} e cm and d_{μ}(ThO)<2×10^{-20} e cm, constitute approximately threefold and ninefold improvements over the limits on d_{μ} extracted from the Brookhaven National Laboratory muon beam experiment.

Bound-state effects on dark matter coannihilation: Pushing the boundaries of conversion-driven freeze-out

Bound-state formation can have a large impact on the dynamics of dark matter freeze-out in the early Universe, in particular for colored coannihilators. We present a general formalism to include an arbitrary number of excited bound states in terms of an effective annihilation cross section, taking bound-state formation, decay and transitions into account, and derive analytic approximations in the limiting cases of no or efficient transitions. Furthermore, we provide explicit expressions for radiative bound-state formation rates for states with arbitrary principal and angular quantum numbers $n,\ell$ for a mediator in the fundamental representation of $SU(3)_c$, as well as electromagnetic transition rates among them in the Coulomb approximation. We then assess the impact of bound states within a model with Majorana dark matter and a colored scalar $t$-channel mediator. We consider the regime of coannihilation as well as conversion-driven freeze-out (or coscattering), where the relic abundance is set by the freeze-out of conversion processes. We find that the region in parameter space where the latter occurs is considerably enhanced into the multi-TeV regime. For conversion-driven freeze-out, dark matter is very weakly coupled, evading direct and indirect detection constraints but leading to prominent signatures of long-lived particles that provide great prospects to be probed by dedicated searches at the upcoming LHC runs.

Magma Mixing During Conduit Flow is Reflected in Melt‐Inclusion Data From Persistently Degassing Volcanoes

AbstractPersistent volcanic activity is thought to be linked to degassing, but volatile transport at depth cannot be observed directly. Instead, we rely on indirect constraints, such as CO2‐H2O concentrations in melt inclusions trapped at different depth, but this data is rarely straight‐forward to interpret. In this study, we integrate a multiscale conduit‐flow model for non‐eruptive conditions and a volatile‐concentration model to compute synthetic profiles of volatile concentrations for different flow conditions and CO2 fluxing. We find that actively segregating bubbles in the flow enhance the mixing of volatile‐poor and volatile‐rich magma in vertical conduit segments, even if the radius of these bubbles is several orders of magnitude smaller than the width of the conduit. This finding suggests that magma mixing is common in volcanic systems when magma viscosities are low enough to allow for bubble segregation as born out by our comparison with melt‐inclusion data: Our simulations show that even a small degree of mixing leads to volatile concentration profiles that are much more comparable to observations than either open‐ or closed‐system degassing trends for both Stromboli and Mount Erebus. Our results also show that two of the main processes affecting observed volatile concentrations, magma mixing and CO2 fluxing, leave distinct observational signatures, suggesting that tracking them jointly could help better constrain changes in conduit flow. We argue that disaggregating melt‐inclusion data based on the eruptive behavior at the time could advance our understanding of how conduit flow changes with eruptive regimes.

Light Sterile Neutrinos

We review the status of light sterile neutrino searches, motivated by the original Short BaseLine (SBL) anomalies. Here, we discuss how sterile neutrino properties can be constrained by different types of neutrino oscillation experiments (considering appearance or disappearance probes in different oscillation channels) and non-oscillation measurements. These latter include experiments aiming at obtaining a value for the absolute scale of neutrino masses (β decay probes) and the indirect constraints that we could obtain from cosmological observations.

Z lepton flavour violation as a probe for new physics at future e^+e^- colliders

In this work we assess the potential of discovering new physics by searching for lepton-flavour-violating (LFV) decays of the Z boson, Zrightarrow ell _i ell _j, at the proposed circular e^+e^- colliders CEPC and FCC-ee. Both projects plan to run at the Z-pole as a “Tera Z factory”, i.e., collecting {mathcal {O}}left( 10^{12} right) Z decays. In order to discuss the discovery potential in a model-independent way, we revisit the LFV Z decays in the context of the Standard Model effective field theory and study the indirect constraints from LFV mu and tau decays on the operators that can induce Zrightarrow ell _i ell _j. We find that, while the Zrightarrow mu e rates are beyond the expected sensitivities, a Tera Z factory is promising for Zrightarrow tau ell decays, probing New Physics at the same level of future low-energy LFV observables.