Grand unified theories (GUTs) are a very well motivated extensions of the Standard Model (SM), but the landscape of models and possibilities is overwhelming, and different patterns can lead to rather distinct phenomenologies. In this work we present a way to automatize the model building process, by considering a top to bottom approach that constructs viable and sensible theories from a small and controllable set of inputs at the high scale. By providing a GUT scale symmetry group and the field content, possible symmetry breaking paths are generated and checked for consistency, ensuring anomaly cancellation, SM embedding and gauge coupling unification. We emphasize the usefulness of this approach for the particular case of a nonsupersymmetric SO(10) model with an intermediate left-right symmetry, and we analyze how low-energy observables such as proton decay and lepton flavor violation might affect the generated model landscape.

We sketch a novel method to search for light di-leptonic resonances by exploiting precision measurements of Drell-Yan production. Motivated by the recent hints of lepton flavor universality violation in $B\to K^{*}{\ell }^{+}{\ell }^{-}$, we illustrate our proposal by studying the case of spin-1 resonances that couple to muons and have masses in the range of a few GeV. We show that the existing LHC data on $pp\to Z/{\gamma }^{*}\to {\mu }^{+}{\mu }^{-}$ put nontrivial constraints on light di-muon resonance interpretations of $B$ decay anomalies in a model-independent fashion. The impact of our proposal on the long-standing discrepancy in the anomalous magnetic moment of the muon is also briefly discussed.

We investigate the ability of the short baseline neutrino (SBN) experimental program at Fermilab to test the globally-allowed ($3+N$) sterile neutrino oscillation parameter space. We explicitly consider the globally-allowed parameter space for the ($3+1$), ($3+2$), and ($3+3$) sterile neutrino oscillation scenarios. We find that SBN can probe with $5\sigma$ sensitivity more than 85%, 95% and 55% of the parameter space currently allowed at 99% confidence level for the ($3+1$), ($3+2$) and ($3+3$) scenarios, respectively, with the ($3+N$) allowed space used in these studies closely resembling that of previous studies [J. M. Conrad, C. M. Ignarra, G. Karagiorgi, M. H. Shaevitz, and J. Spitz, Adv. High Energy Phys. 2013, 1 (2013).], calculated using the same methodology. In the case of the ($3+2$) and ($3+3$) scenarios, $CP$-violating phases appear in the oscillation probability terms, leading to observable differences in the appearance probabilities of neutrinos and antineutrinos. We explore SBN’s sensitivity to those phases for the ($3+2$) scenario through the currently planned neutrino beam running, and investigate potential improvements through additional antineutrino beam running. We show that, if antineutrino exposure is considered, for maximal values of the ($3+2$) $CP$-violating phase ${\varphi }_{54}$, SBN could be the first experiment to directly observe $\sim 2\sigma$ hints of $CP$ violation associated with an extended lepton sector.

We give an accurate determination of the vector (electromagnetic) form factor, $F(Q^2)$, for a light pseudoscalar meson up to squared momentum transfer $Q^2$ values of $6{\mathrm{GeV}}^2$ for the first time from full lattice QCD, including $u$, $d$, $s$ and $c$ quarks in the sea at multiple values of the lattice spacing. Our results show good control of lattice discretization and sea quark mass effects. We study a pseudoscalar meson made of valence $s$ quarks but the qualitative picture obtained applies also to the $\pi$ meson, relevant to upcoming experiments at Jefferson Lab. We find that $Q^{2}F(Q^2)$ becomes flat in the region between $Q^2$ of $2{\mathrm{GeV}}^2$ and $6{\mathrm{GeV}}^2$, with a value well above that of the asymptotic perturbative QCD expectation, but well below that of the vector-meson dominance pole form appropriate to low $Q^2$ values. Our calculations show that we can reach higher $Q^2$ values in future to shed further light on where the perturbative QCD result emerges.

We have investigated the effects of spin-$7/2$ and -$9/2$ nucleon resonances in the kaon photoproduction process $\gamma p\to K^{+}\mathrm{\Lambda }$. To this end, the corresponding propagators were derived from the generalized spin projection operators. To remove the lower spin backgrounds in the scattering amplitude, we used the vertex factors obtained from the consistent interaction Lagrangians inspired by Pascalutsa and Vrancx et al. The scattering amplitude was included in our previous isobar model, and the effects of four nucleon resonances with spins $7/2$ and $9/2$ listed by the Particle Data Group were investigated by making use of all available kaon photoproduction data. A significant improvement to our previous model has been observed in all observables, especially in the beam-recoil double-polarization observables $C_x$, $C_z$, $O_{x^{\prime }}$, and $O_{z^{\prime }}$.

We study the (anti)kaon nucleon interaction in the Skyrme model. The kaon field is introduced as a fluctuation around the rotating Skyrmion for the nucleon. As an extension of our previous work, we study scattering states and examine phase shifts in various kaon-nucleon channels. Then we study the interaction, where we find that it consists of central and spin-orbit components for isospin channels, $I=0$, 1, with an energy dependence and a nonlocality. The interaction is then fitted to a Shrödinger equivalent local potential for s and p waves.

The exclusive photoproduction of $\mathrm{\Upsilon }(nS)$ states was calculated in ultraperipheral collisions for coherent and incoherent process in PbPb at $\sqrt{s_{NN}}=5.5\mathrm{TeV}$. Different dipole models were compared in the theoretical framework of light-cone color dipole formalism. Moreover, we calculated the differential cross section for the Upsilon states and their total cross section for two intervals of rapidity: $|y|\le 4$ 4 and $2\le \mathrm{y}\le 4.5$. A systematic study is done on the theoretical uncertainties associated to the production, and predictions are presented for the first time for the incoherent cross section of the radially excited states.

We report a measurement of cross section $\sigma ({\nu }_{\mu }+\text{nucleus}\to {\mu }^{-}+X)$ and the first measurements of the cross section $\sigma ({\overline{\nu }}_{\mu }+\text{nucleus}\to {\mu }^{+}+X)$ and their ratio $R(\frac{\sigma (\overline{\nu })}{\sigma (\nu )})$ at (anti) neutrino energies below 1.5 GeV. We determine the single momentum bin cross section measurements, averaged over the T2K $\overline{\nu }/\nu$-flux, for the detector target material (mainly carbon, oxygen, hydrogen and copper) with phase space restricted laboratory frame kinematics of ${\theta }_{\mu }<32°$ and $p_{\mu }>500\mathrm{MeV}/c$. The results are $\sigma (\overline{\nu })=(0.900\pm 0.029(\mathrm{stat})\pm 0.088(\mathrm{syst}))\times {10}^{-39}$ and $\sigma (\nu )=(2.41\pm 0.022(\mathrm{stat})\pm 0.231(\mathrm{syst}))\times {10}^{-39}$ in units of ${\mathrm{cm}}^2/\mathrm{nucleon}$ and $R(\frac{\sigma (\overline{\nu })}{\sigma (\nu )})=0.373\pm 0.012(\mathrm{stat})\pm 0.015(\mathrm{syst})$.

We provide a formalism to calculate the cubic interaction vertices of the stable string bit model, in which string bits have $s$ spin degrees of freedom but no space to move. With the vertices, we obtain a formula for one-loop self-energy, i.e., the $\mathcal{O}(1/N^2)$ correction to the energy spectrum. A rough analysis shows that, when the bit number $M$ is large, the ground state one-loop self-energy $\mathrm{\Delta }{E}_G$ scale as $M^{5-s/4}$ for even $s$ and $M^{4-s/4}$ for odd $s$. Particularly, in $s=24$, we have $\mathrm{\Delta }{E}_G\sim 1/M$, which resembles the Poincaré invariant relation of $1+1$ dimension $P^{-}\sim 1/P^{+}$. We calculate analytically the one-loop correction for the ground energies with $M=3$ and $s=1$, 2. We then numerically confirm that the large $M$ behavior holds for $s\le 4$ cases.

In this article, we define and quantize a truncated form of the nonassociative and noncommutative Snyder ${\varphi }^4$ field theory using the functional method in momentum space. More precisely, the action is approximated by expanding up to the linear order in the Snyder deformation parameter $\beta$, producing an effective model on commutative spacetime for the computation of the two-, four- and six-point functions. The two- and four-point functions at one loop have the same structure as at the tree level, with UV divergences faster than in the commutative theory. The same behavior appears in the six-point function, with a logarithmic UV divergence and renders the theory unrenormalizable at ${\beta }^1$ order except for the special choice of free parameters $s_1=-s_2$. We expect effects from nonassociativity on the correlation functions at ${\beta }^1$ order, but these are cancelled due to the average over permutations.

It is known that a quasinormal mode (QNM) of a remnant black hole dominates a ringdown gravitational wave (GW) in a binary black hole (BBH) merger. To study properties of the QNMs, it is important to determine the time when the QNMs appear in a GW signal as well as to calculate its frequency and amplitude. In this paper, we propose a new method of estimating the starting time of the QNM and calculating the QNM frequency and amplitude of BBH GWs. We apply it to simulated merger waveforms by numerical relativity and the observed data of GW150914. The results show that the obtained QNM frequencies and time evolutions of amplitudes are consistent with the theoretical values within 1% accuracy for pure waveforms free from detector noise. In addition, it is revealed that there is a correlation between the starting time of the QNM and the spin of the remnant black hole. In the analysis of GW150914, we show that the parameters of the remnant black hole estimated through our method are consistent with those given by LIGO, and a reasonable starting time of the QNM is determined.

We consider a universe with an arbitrary number of extra dimensions, $N$. We present a new method for constructing the cosmological equations of motion and find analytic solutions with an explicit dependence on $N$. When we take the $N\to \infty$ limit, we find novel emergent behavior which distinguishes it from normal Kaluza-Klein universes.

The large-scale matter distribution in the late-time Universe exhibits gravity-induced non-Gaussianity, and the bispectrum, three-point cumulant is expected to contain significant cosmological information. In particular, the measurement of the bispectrum helps to tighten the constraints on dark energy and modified gravity through the redshift-space distortions. In this paper, extending the work by Taruya, Nishimichi, and Saito [Phys. Rev. D 82, 063522 (2010)], we present a perturbation theory (PT) based model of redshift-space matter bispectrum that can keep the nonperturbative damping effect under control. Characterizing this nonperturbative damping by a univariate function with a single free parameter, the PT model of the redshift-space bispectrum is tested against a large set of cosmological $N$-body simulations, finding that the predicted monopole and quadrupole moments are in good agreement with simulations at the scales of baryon acoustic oscillations (well beyond the range of agreement of standard PT). The validity of the univariate ansatz of the damping effect is also examined, and with the PT calculation at next-to-leading order, the fitted values of the free parameter is shown to consistently match those obtained from the PT model of power spectrum by Taruya, Nishimichi, and Saito.

The diffuse Galactic synchrotron emission should exhibit a low level of diffuse circular polarization ($CP$) due to the circular motions of the emitting relativistic electrons. This probes the Galactic magnetic field in a similar way as the product of total Galactic synchrotron intensity times Faraday depth. We use this to construct an all sky prediction of the so far unexplored Galactic $CP$ from existing measurements. This map can be used to search for this $CP$ signal in low frequency radio data even prior to imaging. If detected as predicted, it would confirm the expectation that relativistic electrons, and not positrons, are responsible for the Galactic radio emission. Furthermore, the strength of real to predicted circular polarization would provide statistical information on magnetic structures along the line-of-sights.

There has recently been interest in multisolar mass primordial black holes (PBHs) as a dark matter candidate. There are various microlensing, dynamical and accretion constraints on the abundance of PBHs in this mass range. Taken at face value, these constraints exclude multisolar mass PBHs making up all of the DM for both the delta-function and extended mass functions. However, the stellar microlensing event rate depends on the density and velocity distribution of the compact objects along the line of sight to the Magellanic Clouds. We study the dependence of the constraints on the local dark matter density and circular speed and also consider models where the velocity distribution varies with radius. We find that the largest mass constrained by stellar microlensing can vary by an order of magnitude. In particular, the constraints are significantly weakened if the velocity dispersion of the compact objects is reduced. The change is not sufficiently large to remove the tension between the stellar microlensing and dynamical constraints. However, this demonstrates that it is crucial to take into account astrophysical uncertainties when calculating and comparing constraints. We also confirm the recent finding that the tension between the constraints is in fact increased for realistic, finite width mass functions.

We report on weakly interacting massive particles (WIMPs) search results in the XENON100 detector using a nonrelativistic effective field theory approach. The data from science run II ($34\mathrm{kg}\times 224.6$ live days) were reanalyzed, with an increased recoil energy interval compared to previous analyses, ranging from $(6.6–240){\mathrm{keV}}_{\mathrm{nr}}$. The data are found to be compatible with the background-only hypothesis. We present 90% confidence level exclusion limits on the coupling constants of WIMP-nucleon effective operators using a binned profile likelihood method. We also consider the case of inelastic WIMP scattering, where incident WIMPs may up-scatter to a higher mass state, and set exclusion limits on this model as well.

With the introduction of a spectral representation, the Schwinger-Dyson equation (SDE) for the fermion propagator is formulated in Minkowski space in QED. After imposing the on-shell renormalization conditions, analytic solutions for the fermion propagator spectral functions are obtained in four dimensions with a renormalizable version of the Gauge Technique anzatz for the fermion-photon vertex in the quenched approximation in the Landau gauge. Despite the limitations of this model, having an explicit solution provides a guiding example of the fermion propagator with the correct analytic structure. The Padé approximation for the spectral functions is also investigated.

We investigate the quarkonium production mechanisms in jets at the LHC, using the fragmenting jet functions (FJF) approach. Specifically, we discuss the jet energy dependence of the $J/\psi$ production cross section at the LHC. By comparing the cross sections for the different NRQCD production channels (${{}^{1}S}_0^{[8]}$, ${{}^{3}S}_1^{[8]}$, ${{}^{3}P}_J^{[8]}$, and ${{}^{3}S}_1^{[1]}$), we find that at fixed values of energy fraction $z$ carried by the $J/\psi$, if the normalized cross section is a decreasing function of the jet energy, in particular for $z>0.5$, then the depolarizing ${{}^{1}S}_0^{[8]}$ must be the dominant channel. This makes the prediction made in [Baumgart et al., J. High Energy Phys. 11 (2014) 003] for the FJF’s also true for the cross section. We also make comparisons between the long distance matrix elements extracted by various groups. This analysis could potentially shed light on the polarization properties of the $J/\psi$ production in high $p_T$ region.

We study $\rho$ meson unpolarized generalized parton distributions based on a light-front constituent quark model where the quark-antiquark-meson vertex is constructed under the symmetric loop momentum convention. The form factors and some other low-energy observables of the $\rho$ meson are calculated. Moreover, the contributions to the form factors and generalized parton distributions from the valence and nonvalence regimes are discussed and analyzed in detail. In the forward limit, the usual structure functions are estimated as well. In addition, by evolving the moments of the obtained structure functions to the scale of the lattice calculation, we give the factorization scale of our quark model. It is found that the present phenomenological model is reasonable to describe the general properties of $\rho$ meson.