We discuss the physics of restricted Weyl invariance, a symmetry of dimensionless actions in four-dimensional curved space time. When we study a scalar field nonminimally coupled to gravity with Weyl(conformal) weight of $-1$ (i.e. scalar field with the usual two-derivative kinetic term), we find that dimensionless terms are either fully Weyl invariant or are Weyl invariant if the conformal factor $\mathrm{\Omega }(x)$ obeys the condition $g^{\mu \nu }{\nabla }_{\mu }{\nabla }_{\nu }\mathrm{\Omega }=0$. We refer to the latter as restricted Weyl invariance. We show that all the dimensionless geometric terms such as $R^2$, $R_{\mu \nu }{R}^{\mu \nu }$ and $R_{\mu \nu \sigma \tau }{R}^{\mu \nu \sigma \tau }$ are restricted Weyl invariant. Restricted Weyl transformations possesses nice mathematical properties such as the existence of a composition and an inverse in four-dimensional space-time. We exemplify the distinction among rigid Weyl invariance, restricted Weyl invariance and the full Weyl invariance in dimensionless actions constructed out of scalar fields and vector fields with Weyl weight zero.

We determine the strength $G_{\mathrm{v}}$ of the vector-type four-quark interaction in the entanglement Polyakov-loop extended Nambu–Jona-Lasinio (EPNJL) model from the results of recent lattice QCD simulations with two-flavor Wilson fermion. The quark number density is normalized by the Stefan-Boltzmann limit. The strength determined from the normalized quark number density at small baryon chemical potential $\mu$ and temperature $T$ (which is higher than the pseudocritical temperature $T_c$ of the deconfinement transition) is $G_{\mathrm{v}}=0.33G_{\mathrm{s}}$, where $G_{\mathrm{s}}$ is the strength of the scalar-type four-quark interaction. We explore the hadron-quark phase transition in the $\mu$-$T$ plane by using the two-phase model in which the quantum hadrodynamics model is used for the hadron phase and the EPNJL model is used for the quark phase. When $G_{\mathrm{v}}=0.33G_{\mathrm{s}}$, the critical baryon chemical potential of the transition at zero $T$ is ${\mu }_c\sim 1.6\mathrm{GeV}$, which accounts for two-solar-mass measurements of neutron stars in the framework of the hadron-quark hybrid star model.

We revisit our previous model proposed by Okada and Yagyu [Phys. Rev. D 89, 053008 (2014)], in which lepton masses, except the tauon mass, are generated at the one-loop level in TeV-scale physics. Although in the previous work, rather large Yukawa coupling constants, i.e., greater than about 3, are required to reproduce the muon mass, we do not need to introduce such large $\mathcal{O}(1)$ couplings. In our model, masses for neutrinos (charged leptons) are generated by higher-dimensional operators with two isospin triplet (singlet and doublet) scalar fields, which are introduced at the one-loop level. Thus, the mass hierarchy between neutrinos and charged leptons can be naturally described by the difference in the number of vacuum expectation values of the triplet fields which must be much smaller than the vacuum expectation values of the doublet field due to the constraint from the electroweak rho parameter. Furthermore, the discrepancy in the measured muon anomalous magnetic moment ($g-2$) from the prediction in the standard model is explained by new particle contributions at the one-loop level. The collider phenomenology is discussed, especially focusing on a signature from doubly charged scalar bosons at the LHC.

In this paper, we investigate the $\gamma p$ photoproduction of jet plus missing energy signal to set limits on the couplings of the fermionic dark matter to the quarks at the LHC via the main reaction $pp\to p\gamma p\to p\chi \chi j$. We assume typical LHC multipurpose forward detectors and work in a model independent effective field theory framework. Typically, when we do the background analysis, we also include their corresponding single diffractive productions. Our result shows that by requiring a $5\sigma$ ($S/\sqrt{B}\ge 5$) signal deviation, with an integrated luminosity of $\mathcal{L}=200{\mathrm{fb}}^{-1}$, the lower bounds of the weakly interacting massive particle masses scale can be detected up to $\mathrm{\Lambda }$ equal to 665.5, 808.9, and 564.0 GeV for the forward detector acceptances ${\xi }_1$, ${\xi }_2$, and ${\xi }_3$, respectively, where $0.0015<{\xi }_1<0.5$, $0.1<{\xi }_2<0.5$ and $0.0015<{\xi }_3<0.15$.

The Higgs boson is produced at the LHC through gluon fusion at roughly the Standard Model rate. New colored fermions, which can contribute to $gg\to h$, must have vectorlike interactions in order not to be in conflict with the experimentally measured rate. We examine the size of the corrections to single and double Higgs production from heavy vectorlike fermions in $SU(2{)}_L$ singlets and doublets and search for regions of parameter space where double Higgs production is enhanced relative to the Standard Model prediction. We compare production rates and distributions for double Higgs production from gluon fusion using an exact calculation, the low energy theorem (LET), where the top quark and the heavy vectorlike fermions are taken to be infinitely massive, and an effective theory (EFT) where top mass effects are included exactly and the effects of the heavy fermions are included to $\mathcal{O}(\frac{1}{M_X^2})$. Unlike the LET, the EFT gives an extremely accurate description of the kinematic distributions for double Higgs production.

We study the pure-gauge sector of an $SU(N)$ gauge theory, equivariantly gauge fixed to $SU(N-1)\times U(1)$, which is an asymptotically free nonlinear sigma model in four dimensions. We show that dimensional transmutation takes place in the large-$N$ limit and elaborate on the relevance of this result for a speculative scenario in which the strong longitudinal dynamics gives rise to a novel Higgs-Coulomb phase.

We develop strategies for enhancing the signal/noise ratio for stochastically sampled correlation functions. The techniques are general and offer a wide range of applicability. We demonstrate the potential of the approach with a generic two-state system and then explore the practical applicability of the method for single hadron correlators in lattice quantum chromodynamics. In the latter case, we determine the ground state energies of the pion, proton, and delta baryon, as well as the ground and first excited state energy of the rho meson using matrices of correlators computed on an exemplary ensemble of anisotropic gauge configurations. In the majority of cases, we find a modest reduction in the statistical uncertainties on extracted energies compared to conventional variational techniques. However, in the case of the delta baryon, we achieve a factor of 3 reduction in statistical uncertainties. The variety of outcomes achieved for single hadron correlators illustrates an inherent dependence of the method on the properties of the system under consideration and the operator basis from which the correlators are constructed.

Inclusive radiative decays $B_c\to \gamma u\overline{d}$ are considered. It is shown that photon emission allows one to bypass the chiral suppression and leads the increase of the branching fraction by about 4 orders of magnitude. The estimates of exclusive decay branching fractions of $B_c$ meson into different sets of $\pi$ mesons are also given.

We study the transverse single spin asymmetry in direct photon production in $pA$ collisions with incoming protons being transversely polarized. To facilitate the calculation, we formulate a hybrid approach in which the nucleus is treated in the color glass condensate framework, while the collinear twist-3 formalism is applied on the proton side. It has been found that an additional term that arises from color entanglement shows up in the spin-dependent differential cross section. The fact that this additional term is perturbatively calculable allows us to quantitatively study color entanglement effects.

We find that, when the dilaton is implemented as a (pseudo-)Nambu-Goldstone boson using a conformal compensator or “conformon” in a hidden gauge symmetric Lagrangian written to $O(p^4)$ from which baryons arise as solitons, namely, skyrmions, the vector manifestation and chiral symmetry restoration at high density predicted in hidden local symmetry theory—which is consistent with Brown-Rho scaling—are lost or sent to infinite density. It is shown that they can be restored if in medium the behavior of the $\omega$ field is taken to deviate from that of the $\rho$ meson in such a way that the flavor $U(2)$ symmetry is strongly broken at increasing density. The hitherto unexposed crucial role of the $\omega$ meson in the structure of elementary baryon and multibaryon systems is uncovered in this work. In the state of half-skyrmions to which the skyrmions transform at a density $n_{1/2}\gtrsim n_0$ (where $n_0$ is the normal nuclear matter density), characterized by the vanishing (space averaged) quark condensate but nonzero pion decay constant, the nucleon mass remains more or less constant at a value $\gtrsim 60\%$ of the vacuum value, indicating a large component of the nucleon mass that is not associated with the spontaneous breaking of chiral symmetry. We discuss its connection to the chiral-invariant mass $m_0$ that figures in the parity-doublet baryon model.

In the framework of QCD factorization we study the direct $CP$ violation in $B\to {\rho }^0(\omega )V\to {\pi }^{+}{\pi }^{-}V$ ($V$ is a vector meson) via the $\rho -\omega$ mixing mechanism. We find that the $CP$ violation can be enhanced by $\rho -\omega$ mixing when the masses of the ${\pi }^{+}{\pi }^{-}$ pairs are in the vicinity of the $\omega$ resonance. For the decay channel of $B^{-}\to {\rho }^0(\omega ){\rho }^{-}\to {\pi }^{+}{\pi }^{-}{\rho }^{-}$, the maximum $CP$ violation can reach 18%. We also discuss the possibility to observe the $CP$ violation at the LHC.

The saturation of the two Weinberg sum rules is studied at finite temperature, using recent independent QCD sum rule results for the thermal behavior of hadronic parameters in the vector and axial-vector channels. Both sum rules are very well satisfied from $T=0$ up to $T/T_c\simeq 0.7–0.8$. At higher temperatures close to $T_c$ a hadronic, pion-loop contribution in the spacelike region proportional to $T^2$, present at leading order in the vector but not in the axial-vector channel, induces an asymmetry leading to a small deviation. In this region, though, QCD sum rules for the hadronic parameters begin to have no solutions, as the hadronic widths of the $\rho$ and the $a_1$ mesons diverge signaling deconfinement. Close to and at $T=T_c$ there are no pions left in the medium and chiral symmetry is restored, so that the sum rules are trivially satisfied.

In this work, we study the interaction between a nucleon and a $P$-wave charmed meson in the $T$ doublet by exchanging a pion. Our calculations indicate that a nucleon and a $P$-wave charmed meson with $J^P=0^{+}$ or $J^P=1^{+}$ in the $T$ doublet can form bound states. We propose the experimental search for these exotic molecular states near the $D_1(2420)N$ and $D_2^{*}(2460)N$ thresholds, where Belle, LHCb, and the forthcoming Belle II have the discovery potential for them.

Two-particle two-hole contributions to electroweak response functions are computed in a fully relativistic Fermi gas, assuming that the electroweak current matrix elements are independent of the kinematics. We analyze the genuine kinematical and relativistic effects before including a realistic meson-exchange current operator. This allows one to study the mathematical properties of the nontrivial seven-dimensional integrals appearing in the calculation and to design an optimal numerical procedure to reduce the computation time. This is required for practical applications to charged-current neutrino scattering experiments, in which an additional integral over the neutrino flux is performed. Finally, we examine the viability of this model to compute the electroweak two-particle–two-hole response functions.

Quark-hadron duality is a key concept in QCD, allowing for the description of physical hadronic observables in terms of quark-gluon degrees of freedom. The modern theoretical framework for its implementation is Wilson’s operator product expansion (OPE), supplemented by analytic extrapolation from large Euclidean momenta, where the OPE is defined, to the Minkowski axis, where observable quantities are defined. Recently, the importance of additional terms in the expansion of QCD correlators near the Minkowski axis, responsible for quark-hadron duality violations (DVs), was emphasized. In this paper we introduce a mathematical tool that might be useful for the study of DVs in QCD. It is based on finding the minimal distance, measured in the $L^{\infty }$ norm along a contour in the complex momentum plane, between a class of admissible functions containing the physical amplitude and the asymptotic expansion predicted by the OPE. This minimal distance is given by the norm of a Hankel matrix that can be calculated exactly, using as input the experimental spectral function on a finite interval of the timelike axis. We also comment on the relation between the new functional tool and the more commonly used ${\chi }^2$-based analysis. The approach is illustrated on a toy model for the QCD polarization function recently proposed in the literature.

The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of $10.7{\mathrm{fb}}^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale.

We present an analytic solution of a Vaidya-charged black hole with a hyperscaling violating factor in an Einstein-Maxwell-dilaton model, where the scalar potential plays a key role in the existence of the solution. By making use of this result, we study the process of thermalization after a global quench in a theory which its gravitational description is provided by the resultant solution in the case of zero charge. In particular, we probe the system by entanglement entropy and show that it exhibits certain scaling behaviors during the process.

We consider a class of gauge-invariant models on the noncommutative space ${\mathbb{R}}_{\lambda }^3$, a deformation of the algebra of functions on ${\mathbb{R}}^3$. Focusing on massless models with no linear $A_i$ dependence, we obtain noncommutative gauge models for which the computation of the propagator can be done in a convenient gauge. We find that the infrared singularity of the massless propagator disappears in the computation of the correlation functions. We show that massless gauge-invariant models on ${\mathbb{R}}_{\lambda }^3$ have quantum instabilities of the vacuum, signaled by the occurrence of nonvanishing one-point functions for some but not all of the components of the gauge potential. The tadpole contribution to the effective action cannot be interpreted as a standard $\sigma$ term. Its global symmetry does not fit with the one of the classical action, reminiscent of an explicit global symmetry breaking term.

I present a method of quantization using cohomology groups extended via coefficient groups of different types. This is possible according to the universal coefficient theorem. I also show that by using this method new features of quantum field theory not visible in the previous treatments emerge. The main argument is that several constructions considered as absolute until now may appear as relative, depending on individual choices of group structures needed to probe a topology. The universal coefficient theorem also gives information about how these structures, as measured by different choices of groups, relate to one another. This may result in the formulation of new dualities and a deeper understanding of the relation between quantum field theories and gravity.

We study the spectrum and perturbative stability of Freund-Rubin compactifications on $M_p\times M_{Nq}$, where $M_{Nq}$ is itself a product of $N$ $q$-dimensional Einstein manifolds. The higher-dimensional action has a cosmological term $\mathrm{\Lambda }$ and a $q$-form flux, which individually wraps each element of the product; the extended dimensions $M_p$ can be anti-de Sitter, Minkowski, or de Sitter. We find the masses of every excitation around this background, as well as the conditions under which these solutions are stable. This generalizes previous work on Freund-Rubin vacua, which focused on the $N=1$ case, in which a $q$-form flux wraps a single $q$-dimensional Einstein manifold. The $N=1$ case can have a classical instability when the $q$-dimensional internal manifold is a product—one of the members of the product wants to shrink while the rest of the manifold expands. Here, we will see that individually wrapping each element of the product with a lower-form flux cures this cycle-collapse instability. The $N=1$ case can also have an instability when $\mathrm{\Lambda }>0$ and $q\ge 4$ to shape-mode perturbations; we find the same instability in compactifications with general $N$, and show that it even extends to cases where $\mathrm{\Lambda }\le 0$. On the other hand, when $q=2$ or 3, the shape modes are always stable and there is a broad class of AdS and de Sitter vacua that are perturbatively stable to all fluctuations.