We evaluate the contribution of inelastic intermediate states (such as $p\to N^{*}$ excitations) to the phase between the one-photon-exchange and the “nuclear” high energy $pp$ scattering amplitudes as $t\to 0$, caused by multiphoton diagrams. It turns out to be rather small—much smaller than to have any influence on the experimental accuracy of the measurements of $\rho$, defined to be the ratio of the real to imaginary parts of the forward nuclear amplitude.

The Georgi-Machacek model allows for a large triplet vacuum expectation value (vev) with a custodial symmetric scalar potential. This manifestly leads to large charged Higgs coupling to SM fermions thus enhancing the detection probability of the model at the Large Hadron Collider. We show that the latest bound from LHC searches on singly charged Higgs scalar decaying to top and bottom quark restricts the triplet vev from above. We demonstrate that the combined limit from theoretical constraints and the latest Higgs data together with this charged Higgs bound can already curb the model parameter space significantly. Further, we propose the charged Higgs decaying to $W^{\pm }$ boson and a SM-like Higgs as a prospective channel to probe the yet unbounded model parameter space at the future run of the LHC. A simple cut-based analysis for this channel has been made showing the parameter region that can be probed with $5\sigma$ significance at the high luminosity LHC run.

We present the first example of a grand unified theory (GUT) with a modular symmetry interpreted as a family symmetry. The theory is based on supersymmetric $SU(5)$ in 6d, where the two extra dimensions are compactified on a $T_2/{\mathbb{Z}}_2$ orbifold. We have shown that, if there is a finite modular symmetry, then it can only be $A_4$ with an (infinite) discrete choice of moduli, where we focus on $\tau =\omega =e^{i2\pi /3}$, the unique solution with $|\tau |=1$. The fields on the branes respect a generalized $CP$ and flavor symmetry $A_4⋉{\mathbb{Z}}_2$ which is isomorphic to $S_4$ which leads to an effective $\mu -\tau$ reflection symmetry at low energies, implying maximal atmospheric mixing and maximal leptonic $CP$ violation. We construct an explicit model along these lines with two triplet flavons in the bulk, whose vacuum alignments are determined by orbifold boundary conditions, analogous to those used for $SU(5)$ breaking with doublet-triplet splitting. There are two right-handed neutrinos on the branes whose Yukawa couplings are determined by modular weights. The charged lepton and down-type quarks have diagonal and hierarchical Yukawa matrices, with quark mixing due to a hierarchical up-quark Yukawa matrix.

When a neutral meson ($P^0$ or ${\overline{P}}^0$) decays to two vector particles, a large number of observables can be constructed from the differential decay rate based on the polarization of the final state. But, theoretically, all of them are not independent to each other and hence, some relations among observables emerge. These relations have been well studied in the scenario with no $T$ and $CPT$ violations in neutral meson mixing and no direct $CP$ violation as well. In this paper, we have studied the relations among observables in the presence of $T$, $CP$, and $CPT$ violating effects in mixing only. We find that except for four of them, all the other old relations get violated and new relations appear if $T$ and $CPT$ violations in mixing are present. The invalidity of these relation will signify the presence of direct violation of $T$, $CP$, and $CPT$ (i.e., a violation in the decay itself).

The LHC copiously produces muons via different processes, and the muon sample will be large at the high-luminosity LHC (HL-LHC). In this work we propose to leverage this large muon sample and utilize the HL-LHC as a muon fixed-target experiment, with the ATLAS calorimeter as the target. We consider a novel analysis for the ATLAS detector, which takes advantage of the two independent muon momentum measurements by the inner detector and the muon system. We show that a comparison of the two measurements, before and after the calorimeters, can probe new force carriers that are coupled to muons and escape detection. The proposed analysis, based on muon samples from $W$ and $Z$ decays only, has a comparable reach to other proposals. In particular, it can explore the part of parameter space that could explain the muon $g-2$ anomaly.

Using holographic subregion complexity, we study the confinement-deconfinement phase transition of a QCD-like gauge theory, holographically. In the model we consider here, we observe a connection between the potential energy of a probe meson and the behavior of its complexity. Moreover, near the critical point, at which the phase transition takes place, our numerical calculations indicate that we need less information to specify a meson in the nonconformal vacuum than in the conformal one, despite the fact that the nonconformal vacuum has larger energy.

We propose a new diagnostic for quantum chaos. We show that the time evolution of complexity for a particular type of target state can provide equivalent information about the classical Lyapunov exponent and scrambling time as out-of-time-order correlators. Moreover, for systems that can be switched from a regular to unstable (chaotic) regime by a tuning of the coupling constant of the interaction Hamiltonian, we find that the complexity defines a new time scale. We interpret this time scale as recording when the system makes the transition from regular to chaotic behavior.

We study the $O(N{)}^3$ supersymmetric quantum field theory of a scalar superfield ${\mathrm{\Phi }}_{abc}$ with a tetrahedral interaction. In the large $N$ limit, the theory is dominated by the melonic diagrams. We solve the corresponding Dyson-Schwinger equations in continuous dimensions below 3. For sufficiently large $N$, we find an IR stable fixed point and computed the $3-\epsilon$ expansion up to the second order of perturbation theory, which is in agreement with the solution of DS equations. We also describe the $1+\epsilon$ expansion of the model and discuss the possibility of adding the Chern-Simons action to gauge the supersymmetric model.

In this article we study the motion of charged particles in the spacetime of a charged rotating scalarized black hole, namely the rotating dyonic black hole in Kaluza-Klein theory found by Rasheed. We derive the equations of motion in the extremal case and present their analytical solutions in terns of elliptic and hyperelliptic functions. Furthermore, we analyze the particle motion with the help of parametric diagrams and effective potentials.

Normally one thinks of the observed cosmological constant as being so small that it can be utterly neglected on typical astrophysical scales, only affecting extremely large-scale cosmology at gigaparsec scales. Indeed, in those situations where the cosmological constant only has a quantitative influence on the physics, a separation of scales argument guarantees the effect is indeed negligible. The exception to this argument arises when the presence of a cosmological constant qualitatively changes the physics. One example of this phenomenon is the existence of outermost stable circular orbits (OSCOs) in the presence of a positive cosmological constant. Remarkably the size of these OSCOs is of a magnitude to be astrophysically interesting. For instance, for galactic masses the OSCOs are of order the intergalactic spacing; for galaxy cluster masses the OSCOs are of order the size of the cluster.

Cosmic strings produce charged particles which, by emitting electromagnetic radiation, partially ionize neutral hydrogen during the dark ages. Corrections to the ionization fraction of neutral hydrogen induced by cosmic strings lead to new constraints on the string tension around $G\mu \sim {10}^{-16}–{10}^{-20}$ for values of the primordial magnetic field greater than $B_0\sim {10}^{-11}\mathrm{G}$.

We discuss the potential of detecting thermal neutrinos from matter-rich binary mergers, via a decades-long multimessenger campaign involving a Mt-scale water Cherenkov neutrino detector and one or more next generation gravitational wave detectors, capable of observing mergers up to redshift $z\sim 2$. The search of neutrinos in time-coincidence with gravitational wave detections will allow to identify single neutrinos from individual mergers above the background, and to study their distributions in energy, redshift and type (double neutron-star or neutron-star-black hole merger) of the candidate sources. We find that, for merger rates consistent with current LIGO-Virgo constraints, and for a $100\mathrm{Mt}·\mathrm{yr}$ exposure, between $\mathcal{O}({10}^{-1})$ and $\mathcal{O}(10)$ neutrino events are expected. For extreme cases of mergers with more than ${10}^{52}\mathrm{ergs}$ emitted in ${\overline{\nu }}_e$, the number of events can be as large as $\sim 100$, with sensitivity to mergers up to redshift $z\sim 0.5$ or so. Such scenarios can already be tested with a $10\mathrm{Mt}·\mathrm{yr}$ exposure, resulting in constraints on the post-merger evolution of the systems being considered.

The deconfinement and chiral phase transitions are studied in the context of the electrized quark matter at finite temperature in the two-flavor Polyakov–Nambu–Jona-Lasinio model. Using the mean field approximation and an electric field independent regularization we show that the effect of temperature and/or electric fields is to partially restore the chiral symmetry. The deconfinement phase transition is slightly affected by the magnitude of the electric field. To this end we show how the effective quark masses and the expectation value of the Polyakov loop are affected by the electric fields at finite temperatures. As a very interesting result, the pseudocritical temperatures for chiral symmetry restoration and deconfinement decrease as we increase the magnitude of the electric fields; however, both start to increase after some critical value of the electric field.

We propose a chiral Pati-Salam theory based on the gauge group $SU(4{)}_C\times SU(2{)}_L\times SU(2{)}_R$. The left-handed quarks and leptons are unified into a fundamental representation of $SU(4{)}_C$, while right-handed quarks and leptons have a separate treatment. The deviations measured in the rare semileptonic decays $B\to D^{(*)}\tau \overline{\nu }$ are explained by a scalar leptoquark which couples to right-handed fields and is contained in the $SU(4{)}_C\times SU(2{)}_R$-breaking scalar multiplet. The measured deviation of lepton flavor universality in the rare decays $\overline{B}\to {\overline{K}}^{(*)}{\ell }^{+}{\ell }^{-}$, $\ell =\mu$, $e$ is explained via the $SU(4{)}_C$ leptoquark gauge boson. The model predicts a new sub-GeV scale sterile neutrino which participates in the anomaly and can be searched for in upcoming neutrino experiments. The theory satisfies the current most sensitive experimental constraints and its allowable parameter regions will be probed as more precise measurements from the LHCb and Belle II experiments become available.

Following updates in the compilation of $e^{+}{e}^{-}\to \text{hadrons}$ data, this work presents reevaluations of the hadronic vacuum polarization contributions to the anomalous magnetic moments of the electron ($a_e$), muon ($a_{\mu }$) and tau lepton ($a_{\tau }$), to the ground-state hyperfine splitting of muonium and also updates the hadronic contributions to the running of the QED coupling at the mass scale of the $Z$ boson, $\alpha (M_Z^2)$. Combining the results for the hadronic vacuum polarization contributions with recent updates for the hadronic light-by-light corrections, the electromagnetic and the weak contributions, the deviation between the measured value of $a_{\mu }$ and its Standard Model prediction amounts to $\mathrm{\Delta }{a}_{\mu }=(28.02\pm 7.37)\times {10}^{-10}$, corresponding to a muon $g-2$ discrepancy of $3.8\sigma$.

We study the phase diagram of strongly interacting matter with light quarks using a recently proposed, small parameter approach to infrared QCD in the Landau gauge. This is based on an expansion with respect to both the inverse number of colors and the pure Yang-Mills coupling in the presence of a Curci-Ferrari mass term. At leading order, this leads to the well-known rainbow equation for the quark propagator with a massive gluon propagator and a tree-level quark-gluon vertex. We solve the latter at nonzero temperature and chemical potential using a simple semianalytic approximation known to capture the essence of chiral symmetry breaking in the vacuum. In the chiral limit, we find a tricritical point which becomes a critical end point in the presence of a nonzero bare quark mass, in agreement with the results of nonperturbative functional methods and model calculations.

We analyze the theoretical description of radiative decays in charmonium. We use an elementary emission decay model to build the most general electromagnetic transition operator. We show that accurate results for the widths can be obtained from a simple quark potential model reasonably fitting the spectroscopy if the complete form of the operator is used instead of its standard $p/m$ approximation and the experimental masses are properly implemented in the calculation.

We investigate the effect of strange-quark degrees of freedom on the formation of inhomogeneous chiral condensates in a three-flavor Nambu–Jona-Lasinio model in mean-field approximation. A Ginzburg-Landau study complemented by a stability analysis allows us to determine in a general way the location of the critical and Lifshitz points, together with the phase boundary where the (partially) chirally restored phase becomes unstable against developing inhomogeneities, without resorting to specific assumptions on the shape of the chiral condensate. We discuss the resulting phase structure and study the influence of the bare strange-quark mass $m_s$ and the axial anomaly on the size and location of the inhomogeneous phase compared to the first-order transition associated with homogeneous matter. We find that, as a consequence of the axial anomaly, the critical and the Lifshitz point split. For realistic strange-quark masses, the effect is, however, very small and becomes sizeable only for small values of $m_s$.

We use heavy baryon chiral perturbation theory to evaluate the two-photon exchange corrections to the low-energy elastic lepton-proton scattering at next-to-leading order accuracy, i.e., $\mathcal{O}(\alpha ,M^{-1})$, including a nonzero lepton mass. We consider the elastic proton intermediate state in the two-photon exchange invoking soft photon approximation. The infrared singular contributions are projected out using dimensional regularization. The resulting infrared singularity-free two-photon exchange contribution is in good numerical agreement with existing predictions based on standard diagrammatic soft photon approximation evaluations.

We perform the potential analysis in the holographic Schwinger effect in a deformed anti–de Sitter (AdS) background with backreaction due to the gluon condensate. We determine the potential by analyzing the classical string action attaching on a probe D3-brane sitting at an intermediate position in the bulk AdS space. It is found that the inclusion of the gluon condensate reduces the production rate, reverse to the effect of the temperature. Also, we evaluate the critical electric field by the Dirac-Born-Infeld (DBI) action.