Considering the 3D Ising universality class of the QCD critical endpoint, we use a universal effective action for the description of the baryon-number density fluctuations around the critical region. Calculating the baryon-number multiplicity moments and determining their scaling with system’s size, we show that the critical region is very narrow in the direction of the baryon chemical potential $\mu$ and wider in the temperature ($T$) direction. In this context, published experimental results on local proton density-fluctuation measurements, obtained by intermittency analysis in transverse momentum space in NA49 central $A+A$ collisions at $\sqrt{s_{NN}}=17.2\mathrm{GeV}$ ($A=\mathrm{C},\mathrm{Si},\mathrm{Pb}$), restrict significantly the location $({\mu }_c,T_c)$ of the QCD critical endpoint. The main constraint is provided by the freeze-out chemical potential of the $\mathrm{Si}+\mathrm{Si}$ system, which shows nonconventional baryon density fluctuations. An indicative solution, ignoring experimental uncertainties, is $119\mathrm{MeV}\le T_c\le 162\mathrm{MeV}$, $252\mathrm{MeV}\le {\mu }_c\le 258\mathrm{MeV}$.

We use the superspace formulation of (massive) IIA supergravity to obtain the explicit form of the dilatino terms, and we find that the quartic-dilatino term is positive. The theory admits a ten-dimensional de Sitter solution, obtained by assuming a nonvanishing quartic-dilatino condensate which generates a positive cosmological constant. Moreover, in the presence of dilatino condensates, the theory admits formal four-dimensional de Sitter solutions of the form $d{S}_4\times M_6$, where $M_6$ is a six-dimensional Kähler-Einstein manifold of positive scalar curvature.

We derive consistency conditions for the CFT data, which systems with exact but spontaneously broken conformal invariance must satisfy.

Once we put a quantum field theory on a curved manifold, it is natural to further assume that coupling constants are position-dependent. The position-dependent coupling constants then provide an extra contribution to the Weyl anomaly so that we may attempt to cancel the entire Weyl anomaly on the curved manifold. We show that such a cancellation is possible for constant Weyl transformation or infinitesimal but generic Weyl transformation in two- and four-dimensional conformal field theories with exactly marginal deformations. When the Weyl scaling factor is annihilated by conformal powers of Laplacian (e.g., by the Fradkin-Tseytlin-Riegert-Paneitz operator in four dimensions), the cancellation persists even at the finite order thanks to a nice mathematical property of the $Q$ curvature under the Weyl transformation.

By generalizing the formalism proposed by Dalibard, Dupont-Roc and Cohen Tannoudji, we study the resonance interatomic energy of two identical atoms coupled to quantum massless scalar fields in a symmetric/antisymmetric entangled state in the Minkowski and cosmic string spacetimes. We find that in both spacetimes, the resonance interatomic energy has nothing to do with the field fluctuations but is attributed to the radiation reaction of the atoms only. We then concretely calculate the resonance interatomic energy of two static atoms near a perfectly reflecting boundary in the Minkowski spacetime and near an infinite and straight cosmic string, respectively. We show that the resonance interatomic energy in both cases can be enhanced or suppressed and even nullified as compared with that in an unbounded Minkowski spacetime, because of the presence of the boundary in the Minkowski spacetime or the nontrivial spacetime topological structure of the cosmic string. Besides, we also discover that the resonance interatomic energy in the cosmic string spacetime exhibits some peculiar properties, making it in principle possible to sense different cosmic string spacetimes via the resonance interatomic energy.

We investigate a model of a supposedly ideal clock based on the decay rate of a charged particle in circular motion in a constant magnetic field. We show that the time measured by an ideal clock depends on the acceleration. However, the effect becomes visible at an order of magnitude of $10^{28}\mathrm{g}$, therefore confirming the validity of the ideal clock hypothesis for realistic accelerations.

Continuous-wave (CW) gravitational waves (GWs) call for computationally-intensive methods. Low signal-to-noise ratio signals need templated searches with long coherent integration times and thus fine parameter-space resolution. Longer integration increases sensitivity. Low-mass x-ray binaries (LMXBs) such as Scorpius X-1 (Sco X-1) may emit accretion-driven CWs at strains reachable by current ground-based observatories. Binary orbital parameters induce phase modulation. This paper describes how resampling corrects binary and detector motion, yielding source-frame time series used for cross-correlation. Compared to the previous, detector-frame, templated cross-correlation method, used for Sco X-1 on data from the first Advanced LIGO observing run (O1), resampling is about $20\times$ faster in the costliest, most-sensitive frequency bands. Speed-up factors depend on integration time and search setup. The speed could be reinvested into longer integration with a forecast sensitivity gain, 20 to 125 Hz median, of approximately 51%, or from 20 to 250 Hz, 11%, given the same per-band cost and setup. This paper’s timing model enables future setup optimization. Resampling scales well with longer integration, and at $10\times$ unoptimized cost could reach respectively $2.83\times$ and $2.75\times$ median sensitivities, limited by spin-wandering. Then an O1 search could yield a marginalized-polarization upper limit reaching torque-balance at 100 Hz. Frequencies from 40 to 140 Hz might be probed in equal observing time with $2\times$ improved detectors.

In this paper we prove the universal nature of the Unruh effect in a general class of weakly nonlocal field theories. At the same time we solve the tension between two conflicting claims published in literature. Our universality statement is based on two independent computations based on the canonical formulation as well as path integral formulation of the quantum theory.

In Hořava-Lifshitz gravity a scaling isotropic in space but anisotropic in spacetime, often called “anisotropic scaling,” with the dynamical critical exponent $z=3$, lies at the base of its renormalizability. This scaling also leads to a novel mechanism of generating scale-invariant cosmological perturbations, solving the horizon problem without inflation. In this paper we propose a possible solution to the flatness problem, in which we assume that the initial condition of the Universe is set by a small instanton respecting the same scaling. We argue that the mechanism may be more general than the concrete model presented here. We rely simply on the deformed dispersion relations of the theory, and on equipartition of the various forms of energy at the starting point.

Gravitational leptogenesis refers to a class of baryogenesis models in which the matter-antimatter asymmetry of the Universe arises through the standard model lepton-number gravitational anomaly. In these models chiral gravitational waves source a lepton asymmetry in standard model neutrinos during the inflationary epoch. We point out that gravitational leptogenesis can be successful in either the Dirac or Majorana neutrino mass scenario. In the Dirac mass scenario, gravitational leptogenesis predicts a relic abundance of sterile neutrinos that remain out of equilibrium, and the lepton asymmetry carried by the standard model sector is unchanged. In the Majorana mass scenario, the neutrinos participate in lepton-number-violating interactions that threaten to wash out the lepton asymmetry during postinflationary reheating. However, we show that a complete (exponential) washout of the lepton asymmetry is prevented if the lepton-number-violating interactions go out of equilibrium before all of the standard model Yukawa interactions come into equilibrium. The baryon and lepton asymmetries carried by right-chiral quarks and leptons are sequestered from the lepton-number violation, and the washout processes only suppress the predicted baryon asymmetry by a factor of ${ϵ}_{\mathrm{w}.\mathrm{o}.}=\pm O(0.1)$. The sign of ${ϵ}_{\mathrm{w}.\mathrm{o}.}$ depends on the model parameters in such a way that a future measurement of the primordial gravitational wave chirality would constrain the scale of lepton-number violation (heavy Majorana neutrino mass).

We discuss quantum gravitational loop effects to observable quantities such as curvature power spectrum and primordial non-Gaussianity of cosmic microwave background (CMB) radiation. We first review the previously shown case where one gets a time dependence for zeta-zeta correlator due to loop corrections. Then we investigate the effect of loop corrections to primordial non-Gaussianity of CMB. We conclude that, even with a single scalar inflaton, one might get a huge value for non-Gaussianity which would exceed the observed value by at least 30 orders of magnitude. Finally we discuss the consequences of this result for scalar driven inflationary models.

We propose an innovative test of Lorentz symmetry by observing pairs of simultaneous parallel extensive air showers produced by the fragments of ultrahigh-energy cosmic ray nuclei which disintegrated in collisions with solar photons. We show that the search for a cross-correlation of showers in arrival time and direction becomes background free for an angular scale $\lesssim 3°$ and a time window $\mathcal{O}(10\mathrm{s})$. We also show that if the solar photo-disintegration probability of helium is $\mathcal{O}({10}^{-5.5})$ then the hunt for spatiotemporal coincident showers could be within range of existing cosmic ray facilities, such as the Pierre Auger Observatory. We demonstrate that the actual observation of a few events can be used to constrain Lorentz violating dispersion relations of the nucleon.

Magnetic reconnection in curved spacetime is studied by adopting a general-relativistic magnetohydrodynamic model that retains collisionless effects for both electron-ion and pair plasmas. A simple generalization of the standard Sweet-Parker model allows us to obtain the first-order effects of the gravitational field of a rotating black hole. It is shown that the black hole rotation acts to increase the length of azimuthal reconnection layers, thus leading to a decrease of the reconnection rate. However, when coupled to collisionless thermal-inertial effects, the net reconnection rate is enhanced with respect to what would happen in a purely collisional plasma due to a broadening of the reconnection layer. These findings identify an underlying interaction between gravity and collisionless magnetic reconnection in the vicinity of compact objects.

We employ perturbative renormalization group and $\epsilon$-expansion to study multicritical single-scalar field theories with higher derivative kinetic terms of the form $\varphi (-\square {)}^k\varphi$. We focus on those with a ${\mathbb{Z}}_2$-symmetric critical point which are characterized by an upper critical dimension $d_c=2nk/(n-1)$ accumulating at even integers. We distinguish two types of theories depending on whether or not the numbers $k$ and $n-1$ are relatively prime. When they are, the critical theory involves a marginal powerlike interaction ${\varphi }^{2n}$ and the deformations admit a derivative expansion that at leading order involves only the potential. In this case we present the beta functional of the potential and use this to calculate some anomalous dimensions and operator product expansion coefficients. These confirm some conformal field theory data obtained using conformal-block techniques, while giving new results. In the second case where $k$ and $n-1$ have a common divisor, the theories show a much richer structure induced by the presence of marginal derivative operators at criticality. We study the case $k=2$ with odd values of $n$, which fall in the second class, and calculate the functional flows and spectrum. These theories have a phase diagram characterized at leading order in $\epsilon$ by four fixed points which apart from the Gaussian UV fixed point include an IR fixed point with a purely derivative interaction.

We present a corrected calculation of the decay widths of the putative exotic heavy ${\mathrm{\Omega }}_c^0$ states to the ground state ${\mathrm{SU}(3)}_{\text{flavor}}$ sextets of heavy baryons. In the article we have used formulas summed over the final spin $1/2$ and $3/2$ sextets. These states, however, are degenerate only in the strict $m_Q\to \infty$ limit, and therefore for phenomenological applications one has to use formulas for fixed final state spin. The correct numerical values of the decay widths are only marginally affected and all conclusions remain unchanged.

We study the mean-field thermodynamics and the characteristics of the net-baryon number fluctuations at the phase boundaries for the chiral and deconfinement transitions in the hybrid quark-meson-nucleon model. The chiral dynamics is described in the linear sigma model, whereas the quark confinement is manipulated by a medium-dependent modification of the particle distribution functions, where an additional scalar field is introduced. At low temperature and finite baryon density, the model predicts a first-, second-order chiral phase transition, or a crossover, depending on the expectation value of the scalar field, and a first-order deconfinement phase transition. We focus on the influence of the confinement over higher-order cumulants of the net-baryon number density. We find that the cumulants show a substantial enhancement around the chiral phase transition; they are not as sensitive to the deconfinement transition.

We present studies that show how multi-parton interaction and color reconnection affect the hadro-chemistry in proton-proton (pp) collisions with special focus on the production of resonances using the pythia8 event generator. We find that color reconnection suppresses the relative production of meson resonances such as ${\rho }_0$ and ${\mathrm{K}}^{*}$, providing an alternative explanation for the ${\mathrm{K}}^{*}/\mathrm{K}$ decrease observed in proton-proton collisions as a function of multiplicity by the ALICE collaboration. Detailed studies of the underlying mechanism causing meson resonance suppression indicate that color reconnection leads to shorter, less energetic strings whose fragmentation is less likely to produce more massive hadrons for a given quark content, therefore reducing ratios such as ${\mathrm{K}}^{*}/\mathrm{K}$ and ${\rho }_0/\pi$ in high-multiplicity pp collisions. In addition, we have also studied the effects of allowing string junctions to form and found that these may also contribute to resonance suppression.

We examine how the breaking of shift symmetry affects the formation of caustics for the standard canonical kinetic theory as well as for the DBI theory. We show, in this case, that the standard canonical kinetic theory is caustic free but the same does not always apply for the DBI model. We make similar arguments about the conformal Galileons. Finally, it is shown that the simple wave condition is not invariant under field redefinitions and the meaning of simple waves after symmetry breaking is discussed.

The relativistic version of finite-range regularization is proposed. The covariant regulator is generated from the nonlocal Lagrangian. This nonlocal interaction is gauge invariant and is applied to study the nucleon electromagnetic form factors at momentum transfer up to $2{\mathrm{GeV}}^2$. Both octet and decuplet intermediate states are included in the one-loop calculation. Using a dipole regulator with $\mathrm{\Lambda }$ around 0.85 GeV, the obtained form factors, electromagnetic radii, as well as the ratios of the form factors are all comparable with the experimental data. This successful application of chiral effective Lagrangian to relatively large momentum transfer makes it possible to further investigation of hadron quantities at high $Q^2$.