We test a technique adopted in the lattice simulations framework, to reconstruct the chiral-phase boundary at real chemical potential, $\mu$, via extrapolation from imaginary $\mu$. We use a low-energy effective model, the quark-meson model, both in the mean-field approximation and within the functional renormalization group, the latter in the local potential approximation. The model provides results both for real and imaginary values of $\mu$; thus a direct comparison can be performed between the prediction of the model for real values of $\mu$ and the ones obtained via extrapolation from the results at imaginary $\mu$. We compute an effective convergence radius for the reconstruction technique, ${\mu }_{\mathrm{conv}}$, and find ${\mu }_{\mathrm{conv}}\approx 263\mathrm{MeV}$. This value sustains the validity of the reconstruction technique also for finite and moderate values of the chemical potential. On the other hand, within our model, ${\mu }_{\mathrm{conv}}$ is smaller then the value of $\mu$ where we find the actual critical endpoint. Near this point of the phase diagram, we find a discrepancy between the actual phase boundary and the one obtained via extrapolation of $\approx 100\%$. Therefore, our results show that the location of the critical endpoint obtained via reconstruction from imaginary $\mu$ might be considered with due caution.

We examine a simple dark sector extension where the observed dark matter (DM) abundance arises from a freeze-in process through the decay of heavy vectorlike quarks into a scalar dark matter candidate. The detection prospects of such DM are challenging due to the feeble nature of the interactions, but these vectorlike quarks can be produced copiously at the LHC, where they decay to standard model quarks along with DM. Depending on the decay rate, this scenario is typically probed through long-lived particle or displaced vertex signatures, assuming a radiation-dominated cosmological background. An alternative hypothesis suggests that the Universe may have experienced a rapid expansion phase instead of the standard radiation-dominated one during freeze-in. This would significantly alter the dark matter phenomenology, requiring a substantial increase in the interaction rate to match the observed relic density, resulting in the rapid decay of the parent particle. As a result, much of the parameter space for this scenario is beyond the reach of traditional long-lived particle and displaced vertex searches. Due to this nonstandard cosmic evolution, existing constraints do not cover the expanded dark matter parameter space. We propose a complementary search strategy to explore this scenario, offering additional limits alongside searches for long-lived particles and displaced vertices. In our search, we investigate the feebly interacting massive particle (FIMP) dark matter model at the LHC using boosted fatjets and significant missing transverse momentum. To improve precision, we include one-loop QCD corrections for LHC production processes and employ a boosted decision tree multivariate analysis, leveraging jet substructure variables to explore a vast parameter space for this minimally extended FIMP dark matter model at the 14 TeV LHC.

We study the possibility of light Dirac neutrino portal dark matter (DM) in an effective field theory setup. Dirac nature of light neutrino automatically includes its right chiral part ${\nu }_R$ which, in our setup, also acts like a portal between DM and the standard model (SM) particles. Considering a Dirac fermion singlet DM stabilized by an unbroken $Z_2$ symmetry, we write down all possible dimension-6 effective operators involving DM-${\nu }_R$ as well as ${\nu }_R$-SM which conserve $Z_2$, global lepton number and SM gauge symmetries. DM thermalization also ensures the thermalization of ${\nu }_R$, leading to enhanced effective relativistic degrees of freedom $N_{\mathrm{eff}}$, within reach of future cosmic microwave background (CMB) experiments. We study the complementarity among DM and CMB related observations for different Lorentz structures of effective operators. We also propose a UV complete gauged B-L symmetric model with Dirac neutrino portal dark matter.

We present a global neutrino oscillation analysis of models with a single large extra dimension in which right-handed neutrinos possess bulk Dirac masses. Two scenarios are considered: large extra dimensions with bulk masses and the dark dimension framework, both predicting a tower of sterile Kaluza-Klein states that mix with active neutrinos. Using data from MINOS/MINOS+, KamLAND, and Daya Bay, we perform a joint likelihood analysis. No signatures of these theories were found. Therefore, we constrain the compactification radius under different bulk mass and Yukawa coupling assumptions. Large positive bulk masses or sizable Yukawas lead to strong bounds, while small couplings or negative bulk masses remain less constrained.

We study the initial state radiation (ISR) process, $e^{-}{e}^{+}{\to }^{*}\gamma \to \gamma +J/\psi$ observed at high luminosity $e^{-}{e}^{+}$ colliders such as $B$ factories, with the ISR photon being emitted through the initial electron or positron, prior to their annihilation. The emitted $J/\mathrm{\Psi }$ is produced through the photon fragmentation process, with the produced $J/\psi$ in turn decaying into a pair of leptons, ${\mu }^{-}+{\mu }^{+}$ through the leptonic decay process, $J/\mathrm{\Psi }\to {\gamma }^{*}\to \gamma {\mu }^{-}{\mu }^{+}$. The cross section for the $J/\mathrm{\Psi }$ production, and the branching ratio for the leptonic decay of $J/\mathrm{\Psi }\to {\mu }^{-}{\mu }^{+}$, both calculated in the framework of Bethe-Salpeter equation are used to work out the cross section for the complete process, $e^{-}{e}^{+}\to \gamma +J/\psi \to \gamma +{\mu }^{-}+{\mu }^{+}$. Our results are compared with the BABAR data, and other models. This study is then extended to production and decays of $\mathrm{\Upsilon }(1S)$ through the ISR process.

In this paper, we analyze the inclusive hadroproduction of heavy charmonia-bottomonia pairs in the color glass condensate framework in the dilute-dense approximation. The production mechanisms can be classified by the number of gluons emitted from projectiles as single- and double-parton scattering. We analyzed separately both types of contributions and evaluated the corresponding impact factors in the leading order in strong coupling ${\alpha }_s$. For the double-parton scattering, the impact factors factorize into a product of impact factors of single charmonia and bottomonia production cross sections, and the cross section in the large-$N_c$ limit reduces to the well-known pocket formula. For the single-parton scattering, we found that the cross section of the process is sensitive to dipole, quadrupole, sextupole, and octupole scattering amplitudes (correlators of Wilson lines), thus opening possibility to study phenomenologically these novel objects. We also made phenomenological estimates of the cross sections in the dilute approximation and found that the provided approach provides a fair qualitative description of the LHCb data for $J/\psi +\mathrm{\Upsilon }(1S)$ production.

We investigate the transition between weak and strong coupling in thermal $\mathcal{N}=4$ supersymmetric Yang-Mills theory as a function of ’t Hooft coupling $\lambda$ for several quantities of phenomenological interest for which next-to-leading order calculations are available in both regimes. We use Padé approximants to interpolate between the weak and strong coupling expansions and determine the location and width of the transition between the asymptotic regimes.

We report the first observation of the two-body baryonic decays $B^{+}\to {\mathrm{\Sigma }}_c(2455{)}^{++}{\overline{\mathrm{\Xi }}}_c^{-}$ and $B^0\to {\mathrm{\Sigma }}_c(2455{)}^0{\overline{\mathrm{\Xi }}}_c^0$ with significances of $7.3\sigma$ and $6.2\sigma$, respectively, including statistical and systematic uncertainties. The branching fractions are measured to be $\mathcal{B}(B^{+}\to {\mathrm{\Sigma }}_c(2455{)}^{++}{\overline{\mathrm{\Xi }}}_c^{-})=(5.74\pm 1.11\pm 0.42_{-1.53}^{+2.47})\times {10}^{-4}$ and $\mathcal{B}(B^0\to {\mathrm{\Sigma }}_c(2455{)}^0{\overline{\mathrm{\Xi }}}_c^0)=(4.83\pm 1.12\pm 0.37_{-0.60}^{+0.72})\times {10}^{-4}$. The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the absolute branching fractions of ${\overline{\mathrm{\Xi }}}_c^{-}$ or ${\overline{\mathrm{\Xi }}}_c^0$ decays. The data samples used for this analysis have integrated luminosities of $711{\mathrm{fb}}^{-1}$ and $365{\mathrm{fb}}^{-1}$, and were collected at the $\mathrm{\Upsilon }(4S)$ resonance by the Belle and Belle II detectors operating at the KEKB and SuperKEKB asymmetric-energy $e^{+}{e}^{-}$ colliders, respectively.

The worldline of an extended body in curved spacetime can be described by the Mathisson-Papapetrou-Dixon equations when its centroid, i.e., its center of mass, is fixed by a spin supplementary condition (SSC). Different SSC choices result in distinct worldlines. To examine the properties of these choices, we investigate the frequency of circular equatorial orbits of extended bodies within the pole-dipole-(spin-induced-)quadrupole approximation moving around a Kerr black hole for the Tulzcyjew-Dixon (TD) and Mathisson-Pirani (MP) SSCs. First, we examine similarities and discrepancies in the prograde and retrograde orbital frequencies by expanding these frequencies in power series of the spin without taking into account the fact that both the position of the centroid and the spin measure change under the transition from one SSC to another. Then, by taking into account the centroid transition laws, we examine the orbital frequencies’ convergence between the nonhelical MP frame and the TD frame. In particular, we demonstrate that, in analogy to the pole-dipole approximation, the transition from one circular orbit to another within the pole-dipole-(spin-induced-)quadrupole approximation under a change in the SSC, results in convergence between the SSCs only up to certain terms in the spin expansion and does not extend to the entire power series. Finally, we discuss the innermost stable circular orbits in the pole-dipole-(spin-induced-)quadrupole approximation under TD and MP SSCs.

In the present work, we analyze the gravitational deflection for a light beam in the weak and strong field regimes for the gravitational analog geometry of an acoustic black hole and acoustic black bounce. Motivationally, the first spacetime arises as an exact solution of the field equations for gravitational black holes in Einstein-scalar-Gauss-Bonnet theory [P. Cañate, J. Sultana, and D. Kazanas, Classical Quantum Gravity 38, 125002 (2021)]. In contrast, the second model arises from the combination of phantom scalar field and nonlinear electrodynamics in general relativity [P. Cañate, [Phys. Rev. D 106, 024031 (2022)]. We construct analytical expressions for the angular deflection of light in both limits and, from them, analyze the construction of the observables, which allow us to relate theoretical models to observational data. We compare these observables and show how much they differ from those obtained in the Schwarzschild solution.

The difference (“mismatch”) between two gravitational-wave signals is often used to estimate the signal-to-noise ratio (SNR) at which they will be distinguishable in a measurement or, alternatively, when the errors in a signal model will lead to biased measurements. It is well known that the standard approach to calculate this “indistinguishability SNR” is too conservative: a model may fail the criterion at a given SNR, but not necessarily incur a biased measurement of any individual parameters. This problem can be solved by taking into account errors orthogonal to the model space (which, therefore, do not induce a bias), and calculating indistinguishability SNRs for individual parameters, rather than the full $N$-dimensional parameter space. We illustrate this approach with the simple example of aligned-spin binary black hole signals, and calculate accurate estimates of the SNR at which each parameter measurement will be biased. In general, biases occur at much higher SNRs than predicted from the standard mismatch calculation. Which parameters are most easily biased depends sensitively on the details of a given waveform model, and the location in parameter space, and in some cases the bias SNR is as high as the conservative estimate. We also illustrate how the parameter bias SNR can be used to robustly specify waveform accuracy requirements for future detectors.

In this paper, we study the spectrum of the Regge poles (RPs), which are the counterparts of quasinormal modes, in a draining bathtub vortex within a two-component Bose-Einstein condensate (BEC) system. We study the gapped excitations of the condensate with the spatially dependent energy gap term using a spatially tunable Rabi coupling, which will be treated as a perturbation. This model serves as an analog of a rotating black hole surrounded by an environmental mass shell. We first compute the semiclassical scattering amplitude with the spatially independent mass effect due to the orbital interference. In the case of the mass-shell, bifurcation of the spectrum is observed, resulting in the destabilization of the RPs. We also study the migration of RPs by shifting the bump position. Our results show that the RPs of the corotating modes exhibit greater stability than those of the counterrotating modes. Large migration and overtaking jumps of the overtone (fundamental RP) leave an imprint on the scattering amplitude at small (large) scattering angles. This can be observed in the scattering interference pattern in experiments.

Gravitational waves (GWs) are lensed by matter, offering a unique probe of both the large-scale structure of the Universe and the fundamental properties of GW propagation. GWs can also be affected by wave optics effects when their wavelength is comparable to the size of the lens. While this regime has been well studied in the Newtonian approximation, the role of strong gravitational fields remains largely unexplored. This is particularly relevant for lensing by intermediate and supermassive black holes (BHs), which can occur near active galactic nuclei or in compact triple systems. In this work, we analyze the lensing of GWs by a non-rotating BH and compare our results to the Newtonian point-mass approximation. We construct frequency-dependent amplification factors that incorporate strong-field effects, revealing explicit polarization mixing and absorption by the event horizon. Using a fiducial GW event, we explore key phenomenological signatures of BH lensing, highlighting new observational opportunities to probe strong gravitational fields through GW lensing.

With the advent of next-generation surveys, constraints on cosmological parameters are anticipated to become more stringent, particularly for the total neutrino mass. This study forecasts such constraints utilizing galaxy clusters from the Chinese Space Station Survey Telescope (CSST). Employing Fisher matrix techniques, we derive the constraint $\sigma (M_{\nu })$ from cluster number counts, cluster power spectrum, and their combination. The investigation covers both the standard cosmological model with massive neutrinos $\nu \mathrm{\Lambda }\mathrm{CDM}$ and the inclusion of dynamical dark energy in the $\nu w_0{w}_a\mathrm{CDM}$ model, revealing a minor impact of dark energy on neutrino mass constraints. We examine the largest source of systematic arising from the mass-observable relation uncertainties and find that, with perfect knowledge of the scaling relation parameters, CSST clusters have the potential to enhance precision, tightening constraints to $\sim 0.03\mathrm{eV}$. We also study the effects of the maximum redshift $z_{\max }$ and other uncertainties, including those in redshift, halo mass function, and bias. Furthermore, we emphasize the significance of accounting for the growth-induced scale-dependent bias effect, which we find can tighten the final constraint by a factor of 1.2–2.2.

We study cosmic magnification beyond lensing in a late-time universe dominated by quintessence and cold dark matter. The cosmic magnification angular power spectrum, especially going beyond the well-known lensing effect, provides an independent avenue for investigating the properties of quintessence, and hence, dark energy. By analyzing the magnification power spectrum at different redshifts, it is possible to extract new information about the large-scale imprint of dark energy, including whether we are able to disentangle different models from one another. Using three well-known quintessence models, we analyze the cosmic magnification angular power spectrum while taking relativistic corrections into account. We found that it will be difficult to distinguish between quintessence models, and quintessence from the cosmological constant, in lensing magnification angular power spectrum on large scales, at redshifts $z\le 1$; whereas, when relativistic corrections are incorporated, the total magnification angular power spectrum holds the potential to distinguish between the models, at the given $z$. At $z\ge 3$, the lensing magnification angular power spectrum can be a reasonable approximation of the total magnification angular power spectrum. We also found that both the total relativistic and the Doppler magnification signals, respectively, surpass cosmic variance at $z\le 0.5$; hence, the effect may be detectable at the given $z$. On the other hand, the ISW and the time-delay magnification signals, respectively, are surpassed by cosmic variance on all scales, at epochs up to $z=4.5$, with the gravitational-potential magnification signal being zero.

The swampland conjectures (SCs) propose constraints on effective field theories that can arise from a consistent theory of quantum gravity. Two prominent SCs suggest that the scalar field excursion and the gradient of the potential should be at most $\mathcal{O}(1)$ in Planck units. Using the first data release from the Dark Energy Spectroscopic Instrument (DESI) survey and model-independent reconstructions of the SC-related quantities at late times, via a machine learning approach known as genetic algorithms, we evaluate the consistency of these reconstructions with the SC expectations. Our results indicate that the reconstructed second SC is several $\sigma$’s away from zero, suggesting a steep potential, in contrast to recent model-specific analyses assuming exponential potentials. The novelty of our approach lies in using solely model-independent reconstructions of cosmological observables from DESI, such as the angular diameter distance and the Hubble expansion history. This makes our method readily applicable to forthcoming data from stage IV surveys, providing a framework for further assessing consistency with SCs.

We propose a novel method to study the ultralight bosons, where compact rotating objects undergo the phenomenon of quenched superradiance to create gravitational waves and neutrino flux signals. The neutrino flux results from appropriate coupling between the ultralight bosons and the neutrinos. We consider a heavy sterile neutrino generation from ultralight scalar, which later results in active neutrino flux through neutrino oscillations, whereas we consider active neutrino generation directly from the vector bosons. We study the intertwining of gravitational waves and neutrino flux signals produced from a single source and elaborate if and when the signals can be detected in existing and upcoming experiments in a direct manner.

An axionlike particle $a$ (ALP) can explain the excess of $B\to K+\text{invisible}$ events at Belle II. However, many analyses of ALP scenarios are oversimplified. We revisit the $B\to Ka$ transition rate in a popular minimal and UV complete model with two Higgs doublets (2HDM) and a complex singlet [Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model]. To this end we compare our results with previous studies which derived the $\overline{b}sa$ vertex from the $\overline{b}sA$ vertex, where $A$ is the heavy pseudoscalar of the 2HDM, in terms of an $a-A$ mixing angle. We find this approach to work only at the leading one-loop order, while it fails at the two-loop level. Furthermore, while an approximate $Z_2$ symmetry suppresses the leading-order amplitude by a factor of $1/\tan \beta$, which is the ratio of the two vacuum expectation values of the Higgs doublets, we find the two-loop contribution unsuppressed and phenomenologically relevant for $\tan \beta \gtrsim 5$. We determine the allowed parameter space and underline the importance of better searches for $\mathrm{\Upsilon }\to \gamma +\mathrm{invisible}$ and for a possible excess in $B\to K{\mu }^{+}{\mu }^{-}$. We further study the low-energy axion effective theory which leads to a divergent and basis-dependent amplitude. As a conceptual result, we clarify the ambiguities and identify which low-energy framework is consistent with the DFSZ model.

Many experiments have notably reported anomalies in radioactive decay rates with periodic variations and challenged the traditional belief of time-independent decays. This periodicity could potentially be explained by the presence of a periodic dark matter (DM) candidate. In this work, we investigate the impact of time-dependent nuclear decay rates on the ultralight scalar DM in the Nelson-Barr solution to the strong $CP$ problem. The light scalar DM field in this framework induces periodic modulations of both Cabibbo-Kobayashi-Maskawa matrix elements and quark mass parameters. These modulations generate corresponding periodic perturbations in the neutron-proton mass difference and nuclear binding energies. Consequently, nuclear decay rates receive oscillating residuals. By analyzing the tritium decay rate, we derive new exclusion bounds on the Nelson-Barr DM parameters.

We study the forward-backward azimuthal angular correlations of hadrons in association with multiparticle production in the central rapidity region in proton-proton collisions at the LHC. We apply the nucleon energy-energy correlator framework, where the spinning gluon distribution introduces a nontrivial $\cos (2\varphi )$ asymmetries. We will demonstrate that the fundamental helicity structure of quantym chromodynamics (QCD) amplitudes predicts a unique power counting rule: $\cos (2\varphi )$ asymmetry starts at $\mathcal{O}({\alpha }_s^2)$ order for dijet, $\mathcal{O}({\alpha }_s)$ for three jet and $\mathcal{O}(1)$ for four (and more) jet productions. Our results will help us to understand the longstanding puzzle of nearside ridge behavior observed in high multiplicity events of $pp$ collisions at the LHC.