We derive the full set of beta functions for the marginal essential couplings of projectable Hořava gravity in ($3+1$)-dimensional spacetime. To this end we compute the divergent part of the one-loop effective action in static background with an arbitrary spatial metric. The computation is done in several steps: reduction of the problem to three dimensions, extraction of an operator square root from the spatial part of the fluctuation operator, and evaluation of its trace using the method of universal functional traces. This provides us with the renormalization of couplings in the potential part of the action which we combine with the results for the kinetic part obtained previously. The calculation uses symbolic computer algebra and is performed in four different gauges yielding identical results for the essential beta functions. We additionally check the calculation by evaluating the effective action on a special background with spherical spatial slices using an alternative method of spectral summation. We conclude with a preliminary discussion of the properties of the beta functions and the resulting renormalization group flow, identifying several candidate asymptotically free fixed points.

Massive stellar origin black hole binaries (SBHBs), originating from stars above the pair-instability mass gap, are primary candidates for multiband gravitational wave (GW) observations. Here we study the possibility to use them as effective dark standard sirens to constrain cosmological parameters. The long lasting inspiral signal emitted by these systems is accessible by the future Laser Interferometer Space Antenna (LISA), while the late inspiral and merger are eventually detected by third generation ground-based telescopes such as the Einstein Telescope (ET). The direct measurement of the luminosity distance and the sky position to the source, together with the inhomogeneous redshift distribution of possible host galaxies, allow us to infer cosmological parameters by probabilistic means. The efficiency of this statistical method relies in high parameter estimation performances. We show that this multiband approach allows a precise determination of the Hubble constant ${\mathrm{H}}_0$ with just $\mathcal{O}(10)$ detected sources. For selected SBHB population models, assuming 4 (10) years of LISA observations, we find that ${\mathrm{H}}_0$ is typically determined at $\sim 2\%$ ($\sim 1.5\%$), whereas ${\mathrm{\Omega }}_m$ is only mildly constrained with a typical precision of 30% (20%). We discuss the origin of some outliers in our final estimates and we comment on ways to reduce their presence.

Current measurements of Standard Model parameters suggest that the electroweak vacuum is metastable. This metastability has important cosmological implications, because large fluctuations in the Higgs field could trigger vacuum decay in the early Universe. For the false vacuum to survive, interactions which stabilize the Higgs during inflation—e.g., inflaton-Higgs interactions or nonminimal couplings to gravity—are typically necessary. However, the postinflationary preheating dynamics of these same interactions could also trigger vacuum decay, thereby recreating the problem we sought to avoid. This dynamics is often assumed catastrophic for models exhibiting scale invariance, since these generically allow for unimpeded growth of fluctuations. In this paper, we examine the dynamics of such “massless preheating” scenarios and show that the competing threats to metastability can nonetheless be balanced to ensure viability. We find that fully accounting for both the backreaction from particle production and the effects of perturbative decays reveals a large number of disjoint “islands of (meta)stability” over the parameter space of couplings. Ultimately, the interplay among Higgs-stabilizing interactions plays a significant role, leading to a sequence of dynamical phases that effectively extend the metastable regions to large Higgs-curvature couplings.

We study in detail the sensitivity of the Antarctic Impulsive Transient Antenna (ANITA) to possible ${\nu }_{\tau }$ point source fluxes detected via $\tau$-lepton-induced air showers. This investigation is framed around the observation of four upward-going extensive air shower events very close to the horizon seen in ANITA-IV. We find that these four upgoing events are not observationally inconsistent with $\tau$-induced EASs from Earth-skimming ${\nu }_{\tau }$ both in their spectral properties as well as in their observed locations on the sky. These four events as well as the overall diffuse and point source exposure to Earth-skimming ${\nu }_{\tau }$ are also compared against published ultrahigh-energy neutrino limits from the Pierre Auger Observatory. While none of these four events occurred at sky locations simultaneously visible by Auger, the implied fluence necessary for ANITA to observe these events is in strong tension with limits set by Auger across a wide range of energies and is additionally in tension with ANITA’s Askaryan in-ice neutrino channel above ${10}^{19}\mathrm{eV}$. We conclude by discussing some of the technical challenges with simulating and analyzing these near horizon events and the potential for future observatories to observe similar events.

The covariant quantization of QED and QCD requires the introduction of subsidiary gauge-fixing and ghost fields and it is crucial to understand the role of these in the energy-momentum tensor, and in the momentum and angular momentum operators. These issues were discussed by E. Leader [Phys. Rev. D 83, 096012 (2011)], and certain key results from this study, namely that the subsidiary and ghost fields do not contribute to the physical matrix elements of the canonical or Bellinfante momentum and angular momentum, were utilized in the major review of angular momentum by E. Leader and C. Lorce [Phys. Rep., 541, 163 (2014)]. B. Damski [Phys. Rev. D 104, 085003 (2021)] has rightly criticized as incorrect the derivation of these results for the QED case by Leader (2011) and has given explicit expressions for the contribution of the subsidiary fields to the physical matrix elements of the QED momentum and angular momentum. We show, however, that the key results of Leader (2011), mentioned above, which are utilized by Leader and Lorce (2014), are unaffected by Damski’s criticism and that his expressions for the contribution from the subsidiary fields, in fact, vanish.

We study the emergence of color superconductivity in the theory of the strong interaction at supranuclear densities. To this end, we follow the renormalization group (RG) flow of dense strong-interaction matter with two massless quark flavors from the fundamental quark and gluon degrees of freedom at high energies down to the nonperturbative low-energy regime which is found to be governed by the dynamical formation of diquark states. With the strong coupling at the initial RG scale as the only input parameter, we compute the (chirally symmetric) scalar diquark condensate and analyze its scaling behavior over a wide range of the quark chemical potential. Approximations entering our computations are critically assessed. Since our approach naturally allows us to study the scale dependence of couplings, we also monitor the strength of couplings appearing in low-energy models of dense strong-interaction matter. The observed dependence of these couplings on the quark chemical potential may help to amend model studies in the future. Finally, we estimate the speed of sound of dense QCD matter. Our results indicate that the speed of sound exceeds the value of the noninteracting quark gas at high densities and even increases as the density is decreased, across a wide range, suggesting the existence of a maximum at supranuclear densities.

We study properties of the thermal transition in QCD, using anisotropic, fixed-scale lattice simulations with $N_f=2+1$ flavors of Wilson fermion. Observables are compared for two values of the pion mass, focusing on chiral properties. Results are presented for the Polyakov loop, various susceptibilities, the chiral condensate and its susceptibility, and the onset of parity doubling in the light and strange baryonic sector.

The Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ is extracted from exclusive semileptonic $B\to D^{(*)}$ decays adopting a novel unitarity-based approach which allows one to determine in a full nonperturbative way the relevant hadronic form factors (FFs) in the whole kinematical range. By using existing lattice computations of the $B\to D^{(*)}$ FFs at small recoil from FNAL/MILC and JLQCD Collaborations, we show that it is possible to extrapolate their behavior also at large recoil without assuming any specific momentum dependence and without constraining their shape using experimental data. Thus, we address the extraction of $|V_{cb}|$ from the experimental data on the semileptonic $B\to D^{(*)}\ell {\nu }_{\ell }$ decays, obtaining $|V_{cb}|=(41.0\pm 1.2)\times {10}^{-3}$ from $B\to D$ using as input the final FNAL/MILC lattice data for the FFs and $|V_{cb}|=(40.4\pm 1.8)\times {10}^{-3}$ from $B\to D^{*}$ using the preliminary JLQCD lattice data. Our result from $B\to D$ is consistent within $\sim 1$ standard deviation with the most recent inclusive determination $|V_{cb}{|}_{\mathrm{incl}}=(42.00\pm 0.65)\times {10}^{-3}$. The resulting uncertainty is comparable with those obtained in literature using experimental data to constrain the shape of the FFs. Our result from $B\to D^{*}$, though consistent with $|V_{cb}{|}_{\mathrm{incl}}$, is still based on preliminary lattice data for the FFs and its uncertainty, is greater than the ones obtained in literature using experimental data to constrain the shape of the FFs. We investigate also the issue of lepton flavor universality thanks to new theoretical estimates of the ratios $R(D^{(*)})$, namely $R(D)=0.296(8)$ using final FNAL/MILC lattice results, and $R(D^{*})=0.261(20)$ using preliminary JLQCD and FNAL/MILC lattice data. Our findings differ by $\sim 1.4\sigma$ from the latest experimental determinations.

We investigate constraints on the dark photon arising from an analysis of deep inelastic scattering data. We perform extractions of parton distribution functions with and without a dark photon being present and allow the dark photon mixing parameter and mass to vary. We also include the effects of vector-meson dominance to ensure the correct photoproduction limit. By considering the variation of the total ${\chi }^2$ arising from such extractions, we infer exclusion limits on the kinetic mixing parameter of the dark photon for dark photon mass up to 80 GeV.

We study a holographic renormalization group (RG) flow triggered by a classically marginal operator. When a marginal operator deforms a conformal field theory, it does not yield a nontrivial RG flow at the classical level. At the quantum level, however, quantum corrections modify a marginal operator into one of the truly marginal, marginally relevant, and marginally irrelevant operators. This quantum correction may generate a nontrivial RG flow. We investigate how we can describe such an RG flow holographically with quantum corrections. Applying the holographic technique, we look into the change of physical quantities, like a coupling constant and vacuum expectation value, along the RG flow. We also study the holographic description of the trace anomaly caused by the gluon condensation.

The Blandford-Znajek process, which uses a magnetized plasma to extract energy from a rotating black hole, is one of the leading candidates for powering relativistic jets. In this work, we investigate the Blandford-Znajek process in two well-motivated quadratic gravity theories: scalar Gauss-Bonnet and dynamical Chern-Simons gravity. We solve analytically for a split-monopole magnetosphere to first order in the small-coupling approximation and second relative order in the slow-rotation approximation. The extracted power at fixed spin and magnetic flux is enhanced in scalar Gauss-Bonnet and reduced in dynamical Chern-Simons gravity, compared to general relativity. We find that there is a degeneracy between spin and the coupling constants of the theories at leading order in the slow rotation approximation that is broken at higher orders.

We explore a model of two-field inflation with a power-law potential in which two identical matter sectors decoupled from each other may reheat to different temperatures while preserving the symmetry of the Lagrangian. This scenario is motivated by mirror dark matter models in which the temperature of the mirror sector is constrained to be $T^{\prime }\lesssim 0.5\mathrm{T}$ by big bang nucleosynthesis and the cosmic microwave background. For powers $p<2$, we find that the symmetric field trajectory $X=Y$ is a repeller solution, such that any randomly occurring asymmetry in the initial conditions is amplified by many orders of magnitude during inflation, especially in a given class of models with nonminimal kinetic terms. Isocurvature fluctuations are strongly suppressed in this model, but a $\mathcal{O}(0.03–0.07)$ tensor-to-scalar ratio could be observed in the near future. The range of potential parameters compatible with Planck constraints is shown to be much larger than in corresponding single-field models. This occurs because the curved field trajectory at horizon crossing leads to a lower spectral index.

A polarization analysis is performed for the recent observation of $Z_{cs}$ exotic state in the $e^{+}{e}^{-}$ annihilation experiment with motivation for measuring its spin quantum number in the future. Starting with the unpolarized electron and positron beam, the polarization transfer to the $Z_{cs}$ state and its decay angular distribution patterns are investigated. Some observables are suggested for determination of the spin parity quantum numbers. An ensemble of Monte-Carlo events is used to show some moment distributions special for manifestation of the different $Z_{cs}$ spin scenarios.

We calculate the masses of the $qq\overline{q}\overline{q}$ tetraquark ground state and first radial excited state in a constituent quark model where the Cornell-like potential and one-gluon exchange spin-spin coupling are employed. The three coupling parameters for the Cornell-like potential and one-gluon exchange spin-spin coupling are proposed mass-dependent in accordance with lattice QCD data, and all model parameters are predetermined by studying light, charmed, and bottom mesons. The theoretical predictions for light tetraquarks are compared with the observed exotic meson states in the light-unflavored meson sector, and tentative assignments are suggested. The work suggests that $f_0(1500)$ and $f_0(1710)$ might be ground light tetraquark states with $J=0$.

We study an Abelian gauge extension of the standard model with fermion families having nonuniversal gauge charges. The gauge charges and scalar content are chosen in such an anomaly-free way that only the third generation fermions receive Dirac masses via renormalizable couplings with the Higgs boson. Incorporating additional vectorlike fermions and scalars with appropriate $U(1)$ charges can lead to radiative Dirac masses of first two generations with neutral fermions going in the loop being dark matter candidates. Focusing on radiative muon mass, we constrain the model from the requirement of satisfying muon mass, recently measured muon anomalous magnetic moment by the E989 experiment at Fermilab, along with other experimental bounds including the large hadron collider (LHC) limits. The anomalous Higgs coupling to muon is constrained from the LHC measurements of Higgs to dimuon decay. The singlet fermion dark matter phenomenology is discussed showing the importance of both annihilation and coannihilation effects. Incorporating all bounds lead to a constrained parameter space which can be probed at different experiments.

We investigate the efficiency of a gauge invariant input to a neural network for the path optimization method. While the path optimization with a completely gauge-fixed link-variable input has successfully tamed the sign problem in a simple gauge theory, the optimization does not work well when the gauge degrees of freedom remain. We propose to employ a gauge invariant input, such as a plaquette, to overcome this problem. The efficiency of the gauge invariant input to the neural network is evaluated for the two-dimensional $U(1)$ gauge theory with a complex coupling. The average phase factor is significantly enhanced by the path optimization with the plaquette input, indicating good control of the sign problem. It opens a possibility that the path optimization is available to complicated gauge theories, including quantum chromodynamics, in a realistic setup.

Locally ${\mathrm{AdS}}_{d-1}\times \mathbb{R}$ uniform black strings (UBS) in the presence of a massless scalar field are believed to avoid the onset of the Gregory-Laflamme (GL) instability in $d\ge 4$ as no tachyonic modes exist in the spectrum of the Laplace-Beltrami operator. We present analytic and numerical evidence of GL modes in the Lichnerowicz spectrum indicating that ${\mathrm{AdS}}_{d-1}$ UBSs are classically and thermodynamically unstable at the linear level in $d>4$. In $d=4$, we confirm that uniform ${\mathrm{BTZ}}_3$ strings are indeed stable as previously suggested. This supports that linear instabilities of black strings are triggered only if tachyonic modes exist in the Lichnerowicz spectrum. At the end state of the instability, ${\mathrm{AdS}}_{d-1}$ UBSs of finite length may tunnel to a ${\text{SAdS}}_d$ black hole or converge onto a novel nonuniform ${\mathrm{AdS}}_d$ black string. We conjecture that weak cosmic censorship is violated if the nonuniform solution is an exact ${\mathrm{AdS}}_d$ black funnel and compute entropy estimates in $d>4$ as evidence.

We show that the final-state interaction perfectly explains the recent experimental data of the BESIII Collaboration on the near-threshold invariant-mass spectrum of $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ in the process $e^{+}{e}^{-}\to \varphi \mathrm{\Lambda }\overline{\mathrm{\Lambda }}$. The position of the peak in the invariant-mass spectrum is above the threshold, though the interaction of $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ is due to an attractive potential. This potential has a simple form and depends only on two parameters. We show that the invariant-mass spectrum is consistent with the quantum numbers $J^{PC}=1^{++}$ and $2^{++}$ of $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ pair but the quantum numbers $J^{PC}=2^{-+}$ are less likely.

In high energy exclusive processes involving leptons, QED corrections can be sensitive to infrared scales like the lepton mass and the soft photon energy cut, resulting in large logarithms that need to be resummed to all order in $\alpha$. When considering the ratio of the exclusive processes between two different lepton flavors, the ratio $R$ can be expressed in terms of factorized functions in the decoupled leptonic sectors. While some of the functional terms cancel, there remain the large logarithms due to the lepton mass difference and the energy cut. This factorization process can be universally applied to the exclusive processes such as $Z\to l^{+}{l}^{-}$ and $B^{-}\to l^{-}{\overline{\nu }}_l$, where the resummed result in the ratio gives significant deviations from the naive expectation from lepton universality.

In this work we show that the introduction of an appropriate cutoff in the spectra of the Laplacian of an spherically symmetric and static black hole reveals an equivalence between shape and holographic degrees of freedom. Even more, the aforementioned cutoff introduces a correction to the Bekenstein-Hawking entropy which resembles the corresponding holographic loop quantum gravity, generalized uncertainty principle and entanglement entropy corrections. The difficulty of extending our results to nonspherically symmetric black holes is pointed out.