Nuclear star clusters, which fragment into metal-poor stars in situ at the centers of protogalaxies, provide ideal environments for the formation of intermediate-mass black holes with masses ${10}^3–{10}^6{M}_{\odot }$. We utilize the semianalytic model implemented in rapster, a public rapid cluster evolution code. We implement simple recipes for stellar collisions and gas accretion/expulsion into the code and identify the regimes where each channel contributes to the dynamical formation of intermediate-mass black holes via repeated mergers of stellar black hole seeds. We find that intermediate-mass black hole formation in gas-rich environments is almost inevitable if the initial mean density of the nuclear cluster is $>{10}^8{M}_{\odot }{\mathrm{pc}}^{-3}$. A million solar mass black hole can form within 100 Myr in the heaviest ($>{10}^7{M}_{\odot }$) and most compact ($<0.5\mathrm{pc}$) nuclear clusters. We demonstrate that by today these resemble the observed range of nuclear clusters in dwarf galaxies and that there are potential gravitational-wave signatures of the massive black hole formation process.

The advent of gravitational wave astronomy has seen a huge influx of new predictions for potential discoveries of beyond the Standard Model fields. The coupling of all fundamental fields to gravity, together with its dominance on large scales, makes gravitational physics a rich laboratory to study fundamental physics. This holds especially true for the search for the elusive dark photon, a promising dark matter candidate. The dark photon is predicted to generate instabilities in a rotating black hole spacetime, birthing a macroscopic Bose-Einstein condensate. These condensates can especially form around super massive black holes, modifying the dynamical inspiralling process. This then opens another window to leverage future space-borne gravitational wave antennas to join the hunt for the elusive dark matter particle. This study builds a preliminary model for the gravitational waveform emitted by such a dressed extreme mass-ratio inspiral. Comparing these waveforms to the vacuum scenario allows projections to the potential constrainability on the dark photon mass by space-borne gravitational wave antennas. The superradiant instability of a massive vector field on a Kerr background is calculated and, under reasonable approximations, the backreaction on the orbit of an inspiralling solar mass-scale compact object due to the secular evolution of the resulting boson cloud is determined. The end result is the projection that the LISA mission should be able to constrain the dark photon mass using extreme mass ratio inspirals in the range $[1.8\times {10}^{-17},4.47\times {10}^{-16}]\mathrm{eV}$.

This work elaborates on an algebraic approach to second-generation time-delay interferometry (TDI). The proposed method is closely related to the algorithm first developed by Dhurandhar et al. and its recent generalizations. While the relevant equation is derived from a geometric TDI perspective, the resulting TDI solutions are primarily generated by a basis consisting of four-tuples. Unlike the original study, the present scheme is not subject to any constraint equation and spans the underlying solution space much further. Moreover, the algorithm does not rely on specific subscript permutations regarding the two elements of the commutator that furnishes the TDI solution. Employing the proposed method, we explicitly show that all the existing second-generation TDI combinations, most established via the geometric TDI approach, can be derived. It is argued that the current approach provides an alternative perspective on the algebraic structure of the second-generation TDI solutions.

In this paper, the semileptonic decays $D_s^{+}\to {\pi }^0{\ell }^{+}{\nu }_{\ell }$ with $\ell =(e,\mu )$ are investigated using the light cone sum rule approach. Firstly, the neutral meson mixing scheme between ${\pi }^0$, $\eta$, ${\eta }^{\prime }$ and pseudoscalar gluonium $G$ is discussed in a unified way, which leads to the direct connection between two different channels for $D_s^{+}\to {\pi }^0{\ell }^{+}{\nu }_{\ell }$ and $D_s^{+}\to \eta {\ell }^{+}{\nu }_{\ell }$ by the ${\pi }^0-\eta$ mixing angle. Then we calculate the $D_s\to {\pi }^0$ transition form factors (TFFs) within the QCD light cone sum rule approach up to next-to-leading order correction. At the large recoil point, we have $f_{+}^{D_s^{+}{\pi }^0}(0)=0.0113_{-0.0019}^{+0.0024}$ and $f_{-}^{D_s^{+}{\pi }^0}(0)=0.0020_{-0.0009}^{+0.0008}$. Furthermore, the TFFs are extrapolated to the whole physical $q^2$-region by using the simplified $z(q^2)$-series expansion. The behaviors of TFFs and related three angular coefficient functions $a_{{\theta }_{\ell }}(q^2)$, $b_{{\theta }_{\ell }}(q^2)$ and $c_{{\theta }_{\ell }}(q^2)$ are given. The differential decay widths for $D_s^{+}\to {\pi }^0{\ell }^{+}{\nu }_{\ell }$ with respect to $q^2$ and $\cos {\theta }_{\ell }$ are presented, and also lead to the branching fractions $\mathcal{B}(D_s^{+}\to {\pi }^0{e}^{+}{\nu }_e)=2.60_{-0.51}^{+0.57}\times {10}^{-5}$ and $\mathcal{B}(D_s^{+}\to {\pi }^0{\mu }^{+}{\nu }_{\mu })=2.58_{-0.51}^{+0.56}\times {10}^{-5}$. These results show good agreement with the recent BESIII measurements and theoretical predictions. Then the differential distributions and integrated predictions for three angular observables, i.e. forward-backward asymmetries, $q^2$-differential flat terms and lepton polarization asymmetries are given separately. Lastly, we estimate the ratio for different decay channels, ${\mathcal{R}}_{{\pi }^0/\eta }^{\ell }=1.108_{-0.071}^{+0.039}\times {10}^{-3}$.

We construct an extension of the Standard Model with a scalar leptoquark $\varphi \sim (3,1,-\frac{1}{3})$ and the discrete flavor symmetry $G_f=D_{17}\times Z_{17}$ to explain anomalies observed in charged-current semileptonic $B$ meson decays and in the muon anomalous magnetic moment, together with the charged fermion masses and quark mixing. The symmetry $Z_{17}^{\mathrm{diag}}$, contained in $G_f$, remains preserved by the leptoquark couplings, at leading order, and efficiently suppresses couplings of the leptoquark to the first generation of quarks and/or electrons, thus avoiding many stringent experimental bounds. The strongest constraints on the parameter space are imposed by the radiative charged lepton flavor violating decays $\tau \to \mu \gamma$ and $\mu \to e\gamma$. A detailed analytical and numerical study demonstrates the feasibility to simultaneously explain the data on the lepton flavor universality ratios $R(D)$ and $R(D^{\star })$ and the muon anomalous magnetic moment, while passing the experimental bounds from all other considered flavor observables.

Neutrinoless double beta decay is a textbook example of lepton number violation, often claimed to be a probe of neutrino Majorana mass. However, it could be triggered by new physics; after all, neutrino Majorana mass requires physics beyond the Standard Model. If at least one electron were right-handed, it would automatically signify new physics rather than neutrino mass. In case both electrons were left-handed, the situation would become rather complicated, and additional effort would be needed to untangle the source for this process. We offer a comprehensive study of this issue from both the effective operator approach and the possible UV completions, including the Pati-Salam quark-lepton unification. While neutrino exchange is natural and physically preferred, our findings show that new physics can still be responsible for the neutrinoless double beta decay. In particular, the Pati-Salam theory can do the job, consistently with all the phenomenological and unification constraints, as long as the unification scale lies above ${10}^{12}\mathrm{GeV}$, albeit at the price of fine-tuning of some scalar masses.

This study explores the generation of the observed baryon asymmetry of the Universe within the complex two-Higgs doublet model (C2HDM) while considering theoretical and current experimental constraints. In our investigation, we analyze critical elements of the Higgs potential to understand the phase-transition pattern. Specifically, we examine the formation of the barrier and the uplifting of the true vacuum state, which play crucial roles in facilitating a strong first-order phase transition. Furthermore, we explore the potential gravitational wave signals associated with this phase transition pattern and investigate the parameter space points that can be probed with LISA. Finally, we compare the impact of different approaches to describing the bubble profile on the calculation of the baryon asymmetry. We contrast the typically used kink profile approximation against the explicit solution of the tunneling profile. We find that a non-negligible range of the C2HDM parameter space results in significant discrepancies in the baryon asymmetry estimation between these two approaches. Through an examination of the parameter space, we identify a benchmark point that satisfies the observed baryon asymmetry.

We discuss a class of theories for Majorana neutrinos where the total lepton number is a local gauge symmetry. These theories predict a dark matter candidate from anomaly cancellation. We discuss the properties of the dark matter candidate and using the cosmological bounds, we obtain the upper bound on the lepton number symmetry breaking scale. The dark matter candidate has unique annihilation channels due to the fact that the theory predicts a light pseudo-Goldstone boson, the Majoron, and one can obtain the correct relic density in a large fraction of the parameter space. In this context, the seesaw scale is below the $\mathcal{O}({10}^2)\mathrm{TeV}$ scale and one can hope to test the origin of neutrino masses at current or future colliders. We discuss the lepton number violating Higgs decays and the possibility to observe lepton number violation at the Large Hadron Collider.

We propose using an optical fiber-based interferometer to search for scalar ultralight dark matter (UDM) with particle mass in the range ${10}^{-17}-{10}^{-13}\mathrm{eV}/c^2$ $({10}^{-3}-10\mathrm{Hz})$. Composed of a solid core and a hollow core fiber, the proposed detector would be sensitive to relative oscillations in the fibers’ refractive indices due to scalar UDM-induced modulations in the fine-structure constant $\alpha$. We predict that, implementing detector arrays or cryogenic cooling, the proposed optical fiber-based scalar UDM search has the potential to reach new regions of the parameter space. Such a search would be particularly well-suited to probe for a solar halo of dark matter with a sensitivity exceeding that of previous dark matter searches over the particle mass range $7\times {10}^{-17}-2\times {10}^{-14}\mathrm{eV}/c^2$.

We perform a lattice study of the ($2+1$)-dimensional Gross-Neveu model in a background magnetic field $B$ and at nonzero chemical potential $\mu$. The complex-action problem arising in our simulations using overlap fermions is under control. For $B=0$, we observe a first-order phase transition in $\mu$ even at nonvanishing temperatures. Our main finding, however, is that the rich phase structure found in the limit of infinite flavor number $N_{\mathrm{f}}$ is washed out by the fluctuations present at $N_{\mathrm{f}}=1$. We find no evidence for inverse magnetic catalysis, i.e., the decrease of the order parameter of chiral symmetry breaking with $B$ for $\mu$ close to the chiral phase transition. Instead, the magnetic field tends to enhance the breakdown of chiral symmetry for all values of $\mu$ below the transition. Moreover, we find no trace of spatial inhomogeneities in the order parameter. We briefly comment on the potential relevance of our results for QCD.

We apply dilaton chiral perturbation theory (dChPT) at next-to-leading order to lattice data from the LatKMI Collaboration for the eight-flavor SU(3) gauge theory. In previous work, we found that leading-order dChPT does not account for these data, but that a model extension of leading-order dChPT with a varying mass anomalous dimension describes these data well. Here we calculate the next-to-leading order corrections for the pion mass and decay constant. We focus on these quantities, as data for the dilaton mass are of poorer quality. The application of next-to-leading order dChPT is difficult because of the large number of new low-energy constants, and the results of our fits turn out to be inconclusive. They suggest—yet cannot firmly establish—that the LatKMI mass range might be outside the scope of dChPT.

In $SU(N)$ gauge theories without dynamical quarks, we discuss how configurations with fractional ${\mathbb{Z}}_N$ magnetic charge also have fractional topological charge, $\sim 1/N$, and dominate topologically nontrivial fluctuations in the confining vacuum. They are not solutions of the classical equations of motion, but arise as quantum solutions of the effective Lagrangian, whose size is essentially fixed, on the order of the confinement scale. We give both a general mathematical analysis and illustrative solutions. We discuss strong evidence for this from numerical simulations on the lattice, and suggest definitive tests. We also speculate how these objects change with the introduction of dynamical quarks, and their effects especially at low temperature and nonzero density.

The processes $e^{+}{e}^{-}\to {\mathrm{\Delta }}^{++}{\overline{\mathrm{\Delta }}}^{--}$ and $e^{+}{e}^{-}\to {\mathrm{\Delta }}^{++}\overline{p}{\pi }^{-}+\mathrm{c}.\mathrm{c}.$ are studied for the first time with $179{\mathrm{pb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected with the BESIII detector at center-of-mass energies from 2.3094 to 2.6464 GeV. No significant signal for the $e^{+}{e}^{-}\to {\mathrm{\Delta }}^{++}{\overline{\mathrm{\Delta }}}^{--}$ process is observed and the upper limit of the Born cross section is estimated at each energy point. For the process $e^{+}{e}^{-}\to {\mathrm{\Delta }}^{++}\overline{p}{\pi }^{-}+\mathrm{c}.\mathrm{c}.$, a significant signal is observed at center-of-mass energies near 2.6454 GeV and the corresponding Born cross section is reported.

The emission of $\gamma$-rays after neutron capture in a cryogenic detector can generate monoenergetic nuclear recoils in the sub-keV regime, which is of direct interest for the calibration of dark matter and coherent elastic neutrino-nucleus scattering experiments. Here we show that accurate predictions of the spectra of total energy deposition induced by neutron captures require taking into account the interplay between the development in time of the deexcitation $\gamma$-ray cascade of the target nucleus and that of the associated atomic collisions in matter. We present detailed simulations coupling the fifrelin code for the description of the $\gamma$-ray cascades and the iradina code for the modeling of the fast atomic movements in matter. Spectra of total energy deposition are predicted, and made available to the community, for concrete cases of ${\text{Al}}_2{\mathrm{O}}_3$, Si, Ge, and ${\mathrm{CaWO}}_4$ crystals exposed to a low intensity beam of thermal neutrons. We find that timing effects cause new calibration peaks to emerge in the recoil spectra and also impact the shape of the continuous recoil distribution. We discuss how they could give access to a rich physics program, spanning the accurate study of the response of cryogenic detectors in the sub-keV range, tests of solid state physics simulations, and nuclear models.

The pseudorapidity density of charged particles with minimum transverse momentum ($p_{\mathrm{T}}$) thresholds of 0.15, 0.5, 1, and $2\mathrm{GeV}/c$ is measured in pp collisions at the center of mass energies of $\sqrt{s}=5.02$ and 13 TeV with the ALICE detector. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity ($\eta$) within $\pm 0.8$ and $p_{\mathrm{T}}$ larger than the corresponding threshold. In addition, measurements without $p_{\mathrm{T}}$-thresholds are performed for inelastic and nonsingle-diffractive events as well as for inelastic events with at least one charged particle having $|\eta |<1$ in pp collisions at $\sqrt{s}=5.02\mathrm{TeV}$ for the first time at the LHC. These measurements are compared to the pythia 6, pythia 8, and epos-lhc models. In general, the models describe the $\eta$ dependence of particle production well. However, discrepancies are observed for the highest transverse momentum threshold ($p_{\mathrm{T}}>2\mathrm{GeV}/c$), highlighting the importance of such measurements for tuning event generators. The new measurements agree within uncertainties with results from the ATLAS and CMS experiments obtained at $\sqrt{s}=13\mathrm{TeV}$.

The vector-boson production cross section for the Higgs boson decay in the $H\to W{W}^{*}\to e\nu \mu \nu$ channel is measured as a function of kinematic observables sensitive to the Higgs boson production and decay properties as well as integrated in a fiducial phase space. The analysis is performed using the proton-proton collision data collected by the ATLAS detector in Run 2 of the LHC at $\sqrt{s}=13\mathrm{TeV}$ center-of-mass energy, corresponding to an integrated luminosity of $139{\mathrm{fb}}^{-1}$. The different flavor final state is studied by selecting an electron and a muon originating from a pair of $W$ bosons and compatible with the Higgs boson decay. The data are corrected for the effects of detector inefficiency and resolution, and the measurements are compared with different state-of-the-art theoretical predictions. The differential cross sections are used to constrain anomalous interactions described by dimension-six operators in an effective field theory.

We introduce a technique relying on the use of auxiliary fields in order to eliminate explicit field-derivatives that plague the high orders renormalization group treatment of shift-symmetric (derivative) theories. This technique simplifies drastically the computation of fluctuations in such theories. This is illustrated by deriving the two-loop renormalization group equations—and the three-loop anomalous dimension—of the ${\mathit{\phi }}^4$ derivative theory in $D=4-\epsilon$, which is also relevant to describe the crumpled-to-flat transition of polymerized membranes. Some features of this transition are provided.

Motivated by recent analogies between the large-$q$ complex Sachdev-Ye-Kitaev (cSYK) model and charged black holes, we aim to find a concrete gravitation theory with a matching partition function. Our main focus is to match the thermodynamics of the ($0+1$)-dimensional cSYK model, with that of a ($1+1$)-dimensional gravitational model. We focus on a model of deformed Jackiw-Teitelboim gravity, characterized by some unknown dilaton potential function and unknown dilaton-to-Maxwell field coupling. By finding the general solutions, we are able to find the Lagrangian which produces the same partition function and equation of state as that of the considered SYK model. We go beyond showing that the thermodynamics overlaps by also showing that the Lyapunov exponents, characterizing the degree of chaos, overlap close to the second-order phase transition. In the low-temperature rescaled regime, there remain open questions about the Lyapunov exponents, given that our analysis ignores the black hole backaction which can be large in this regime.

Dual resonance is one of the great miracles of string theory. At a fundamental level, it implies that the particles exchanged in different channels are subtly equivalent. Furthermore, it is inextricably linked to the property of exceptionally tame high-energy behavior. In this paper, we present explicit, closed-form expressions for a new class of dual resonant amplitudes describing an infinite tower of spins for an arbitrary mass spectrum. In particular, the input of our construction is a user-defined, fully customizable choice of masses. The resulting “bespoke” amplitudes are well behaved in the ultraviolet and analytic except at simple poles whose residues are polynomial in the momentum transfer, in accordance with locality. The absence of branch cuts can be seen using Newton’s identities, but can also be made manifest by expressing the amplitudes as a simple $d\log$ integral of the Veneziano amplitude that remaps the linear Regge trajectories of the string to a tunable spectrum. We identify open regions of parameter space that firmly deviate from string theory but nevertheless comport with partial wave unitarity. Last but not least, we generalize our construction to the scattering of any number of particles in terms of a $d\log$ transform of the Koba-Nielsen worldsheet integral formula.

In this paper, we explore the possibility of building a quantum memory that is robust to thermal noise using large $N$ matrix quantum mechanics models. First, we investigate the gauged $SU(N)$ matrix harmonic oscillator and different ways to encode quantum information in it. By calculating the mutual information between the system and a reference which purifies the encoded information, we identify a transition temperature, $T_c$, below which the encoded quantum information is protected from thermal noise for a memory time scaling as $N^2$. Conversely, for temperatures higher than $T_c$, the information is quickly destroyed by thermal noise. Second, we relax the requirement of gauge invariance and study a matrix harmonic oscillator model with only global symmetry. Finally, we further relax even the symmetry requirement and propose a model that consists of a large number $N^2$ of qubits, with interactions derived from an approximate $SU(N)$ symmetry. In both ungauged models, we find that the effects of gauging can be mimicked using an energy penalty to give a similar result for the memory time. The final qubit model also has the potential to be realized in the laboratory.