The interactions of cosmic rays with the solar atmosphere produce secondary particles which can reach the Earth. In this work, we present a comprehensive calculation of the yields of secondary particles such as gamma-rays, electrons, positrons, neutrons, and neutrinos performed with the fluka code. We also estimate the intensity at the Sun and the fluxes at the Earth of these secondary particles by folding their yields with the intensities of cosmic rays impinging on the solar surface. The results are sensitive to the assumptions on the magnetic field nearby the Sun and to the cosmic-ray transport in the magnetic field in the inner Solar System.

We explore screening effects arising from a relativistic magnetized plasma with applications to big bang nucleosynthesis (BBN). The screening potential which depends on the thermodynamics of charged particles in the plasma is altered by the magnetic field. We focus on the impact of screening on the electron capture interaction. Taking into account the correction in BBN arising from a homogeneous primordial magnetic field (PMF), we constrain the epoch at which the PMF was generated and its strength during BBN. Considering such screening corrections to the electron capture rates and using up-to-date observations of primordial elemental abundances, we also discuss the possibility of solving the problem of underestimation of the deuterium abundance. We find for certain values of the PMF strength predicted D and ${}^4\mathrm{He}$ abundances are both consistent with the observational constraints.

In the literature different approaches have been proposed to compute the anisotropies of the astrophysical gravitational wave background. The different expressions derived, although starting from our work [Cusin, Pitrou, Uzan, Phys. Rev. D 96, 103019 (2017)], seem to differ. This article compares the various theoretical expressions proposed so far and provides a separate derivation based on a Boltzmann approach. We show that all the theoretical formula in the literature are equivalent and boil down to the one of [Phys. Rev. D 96, 103019 (2017)] when a proper matching of terms and integration by parts are performed. The difference between the various predictions presented for anisotropies in a cosmological context can only lie in the astrophysical modeling of sources, and neither in the theory nor in the cosmological description of the large scale structures. Finally we comment on the gauge invariance of expressions.

Effects of the quantum interference in collisions of particles have a twofold nature: they arise because of the autocorrelation of a complex scattering amplitude and due to spatial coherence of the incoming wave packets. Both these effects are neglected in a conventional scattering theory dealing with the delocalized plane waves, although they sometimes must be taken into account in particle and atomic physics. Here, we study the role of a transverse coherence length of the packets, putting special emphasis on the case in which one of the particles is twisted, that is, it carries an orbital angular momentum $\ell \hslash$. In $ee,ep$, and $pp$ collisions the interference results in corrections to the plane-wave cross sections, usually negligible at the energies $\sqrt{s}\gg 1\mathrm{GeV}$ but noticeable for smaller ones, especially if there is a twisted hadron with $|\ell |>{10}^3$ in initial state. Beyond the perturbative QCD, these corrections become only moderately attenuated allowing one to probe a phase of the hadronic amplitude as a function of $s$ and $t$. In this regime, the coherence effects can compete with the loop corrections in QED and facilitate testing the phenomenological models of the strong interaction at intermediate and low energies.

This paper discusses possible phenomenological implications for $\mathrm{p}+\mathrm{A}$ and $\mathrm{A}+\mathrm{A}$ collisions of the results of recent numerical AdS/CFT calculations examining asymmetric collisions of planar shocks. In view of the extreme Lorentz contraction, we model highly relativistic heavy ion collisions as a superposition of collisions between many near-independent transverse “pixels” with differing incident longitudinal momenta. It was found that also for asymmetric collisions the hydrodynamization time is in good approximation a proper time, just like for symmetric collisions, depending on the geometric mean of the longitudinally integrated energy densities of the incident projectiles. For realistic collisions with fluctuations in the initial energy densities, these results imply a substantial increase in the hydrodynamization time for highly asymmetric pixels. However, even in this case the local hydrodynamization time still is significantly smaller than perturbative results for the thermalization time.

We introduce a scenario for $CP$-violating (CPV) dark photon interactions in the context of non-Abelian kinetic mixing. Assuming an effective field theory that extends the Standard Model (SM) field content with an additional $U(1)$ gauge boson ($X$) and a $SU(2{)}_L$ triplet scalar, we show that there exist both $CP$-conserving and CPV dimension five operators involving these new degrees of freedom and the SM $SU(2{)}_L$ gauge bosons. The former yields kinetic mixing between the $X$ and the neutral $SU(2{)}_L$ gauge boson (yielding the dark photon), while the latter induces CPV interactions of the dark photon with the SM particles. We discuss experimental probes of these interactions using searches for permanent electric dipole moments (EDMs) and dijet correlations in high-energy $pp$ collisions. It is found that the experimental limit on the electron EDM currently gives the strongest restriction on the CPV interaction. In principle, high-energy $pp$ collisions provide a complementary probe through azimuthal angular correlations of the two forward tagging jets in vector boson fusion. In practice, observation of the associated CPV asymmetry is likely to be challenging.

We consider local (or perturbative) gauge anomalies in models which extend the rank of the Standard Model (SM) gauge group and the chiral fermion content only by $n$ SM singlets. We give a general solution to the anomaly cancellation conditions (ACCs) of an additional $U(1)$ subgroup for the ACCs that involve only SM fermions and we examine whether a corresponding solution exists for the remaining ACCs. We show that a solution to the remaining ACCs always exists for $n\ge 5$ in the family-nonuniversal case or $n\ge 3$ in the family-universal case. In the special case where only a single family carries nonvanishing charges, we find a general solution to all ACCs, for any value of $n$.

Recently, the KOTO experiment at J-PARC has observed three anomalous events in the flavor-changing rare decay $K_L\to {\pi }^0\nu \overline{\nu }$, which indicates that the corresponding branching ratio is almost 2 orders of magnitude larger than the Standard Model (SM) prediction. Taking this intriguing result at face value, we explore model implications of its viable explanation by a long-lived light SM-singlet scalar ($S$) emission, i.e., $K_L\to {\pi }^{0}S$, with $S$ decaying outside the KOTO detector. We derive constraints on the parameter space of such a light scalar in the context of three simple models: (i) a real singlet scalar extension of the SM; (ii) a $B-L$ extension where neutrino masses arise via type-I seesaw mechanism from $B-L$ breaking; and (iii) a TeV-scale left-right symmetric model. The flavor-changing couplings needed to explain the KOTO excess in models (i) and (ii) originate from tree-level mixing of the scalar with SM Higgs field ($h$), and in model (iii), from the mixing of $S$ and $h$ with the neutral component of the heavy bidoublet Higgs field. After taking into account the stringent constraints from high-precision searches for flavor-changing charged and neutral kaon decays at NA62, E949, KOTO and CHARM experiments, as well as the astrophysical and cosmological constraints on a light scalar, such as those from supernova energy loss, big bang nucleosynthesis and relativistic degrees of freedom, we find that the light scalar interpretation of the KOTO excess is allowed in all these models. Parts of the parameter range can be tested in future NA62 and DUNE experiments.

In this paper we describe in detail the computation of the scattering amplitudes of massive spin-2 Kaluza-Klein excitations in a gravitational theory with a single compact extra dimension, whether flat or warped. These scattering amplitudes are characterized by intricate cancellations between different contributions: although individual contributions may grow as fast as $\mathcal{O}(s^5)$, the full results grow only as $\mathcal{O}(s)$. We demonstrate that the cancellations persist for all incoming and outgoing particle helicities and examine how truncating the computation to only include a finite number of intermediate states impacts the accuracy of the results. We also carefully assess the range of validity of the low-energy effective Kaluza-Klein theory. In particular, for the warped case we demonstrate directly how an emergent low-energy scale controls the size of the scattering amplitude, as conjectured by the AdS/CFT correspondence.

The minimal Starobinsky supergravity with inflaton (scalaron) and goldstino in a massive vector supermultiplet is coupled to the dilaton-axion chiral superfield with the no-scale Kähler potential and a superpotential. The Kachru-Kallosh-Linde-Trivedi-type superpotential with a constant term is used to stabilize dilaton and axion during inflation, but it is shown to lead to an instability. The instability is cured by adding the alternative Fayet-Iliopoulos (FI) term that does not lead to the gauged $R$ symmetry. Other stabilization mechanisms, based on the Wess-Zumino-type superpotential, are also studied in the presence of the FI term. A possible connection to the D3-brane models is briefly discussed too.

Discrepancy between the measured value and the Standard Model prediction of the muon anomalous magnetic moment is a possible hint for new physics. A $Z^{\prime }$ particle with $\mu \tau$ flavor violating couplings can give a large contribution to the muon anomalous magnetic moment due to the $\tau$ mass enhancement at the one-loop level, and is known to explain the above discrepancy. In this paper, we study the potential of the Large Hadron Collider (LHC) for detecting such a $Z^{\prime }$ boson via the $pp\to {\mu }^{-}{\mu }^{-}{\tau }^{+}{\tau }^{+}$ process. Earlier studies in the literature only considered the production channel with quark initial states ($pp\to q\overline{q}\to {\mu }^{-}{\mu }^{-}{\tau }^{+}{\tau }^{+}$). Here, we show that the photon initiated process, $pp\to \gamma \gamma \to {\mu }^{-}{\mu }^{-}{\tau }^{+}{\tau }^{+}$, is in fact the dominant production mode, for a heavy $Z^{\prime }$ boson of mass greater than a few hundred GeV. The potential of the high luminosity (HL) LHC is also considered.

We test the impact of the ATLAS and CMS multilepton searches performed at the LHC with 8 as well as 13 TeV center-of-mass energy (using only the pre-2018 results) on the chargino and neutralino sector of the next-to-minimal supersymmetric Standard Model (NMSSM). Our purpose consists in analyzing the actual reach of these searches for a full model and in emphasizing effects beyond the minimal supersymmetric Standard Model (MSSM) that affect the performance of current (MSSM-inspired) electroweakino searches. To this end, we consider several scenarios characterizing specific features of the NMSSM electroweakino sector. We then perform a detailed collider study, generating Monte Carlo events through pythia and testing against current LHC constraints implemented in the public tool checkmate. We find e.g., that supersymmetric decay chains involving intermediate singlino or Higgs-singlet states can modify the naive MSSM-like picture of the constraints by inducing final states with softer or less easily identifiable SM particles—reversely, a compressed configuration with singlino next-to-lightest supersymmetric particle occasionally induces final states that are rich with photons, which could provide complementary search channels.

The unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix has been well established by both direct and indirect measurements without any evidence of discrepancy. The CKM weak phase $\alpha$ is directly measured using an isospin analysis in $B\to \pi \pi$ and $B\to \rho \rho$ assuming that electroweak penguin contributions are ignorable. However, electroweak penguins are sensitive to NP, hence, it is important to experimentally estimate their effects. We determine the size of both electroweak penguin and isospin amplitudes, directly from $B\to \pi \pi$ and $B\to \rho \rho$ experimental data, using in addition the indirectly measured value of $\alpha$. We find that electroweak penguin contribution are indeed small and agree with SM expectations within $1\sigma$. We also find that there is a mild enhancement of the $\mathrm{\Delta }I=\frac{1}{2}$ transition amplitude.

Starting from the Hamiltonian formulation of supersymmetric Calogero models associated with the classical $A_n$, $B_n$, $C_n$ and $D_n$ series we construct the $\mathcal{N}=2$ and $\mathcal{N}=4$ supersymmetric extensions of their hyperbolic/trigonometric Calogero-Sutherland cousins. The bosonic core of these models are the standard Calogero-Sutherland hyperbolic/trigonometric systems.

We perform the Hamiltonian analysis of unimodular gravity in terms of the connection representation. The unimodular condition is imposed straightforwardly into the action with a Lagrange multiplier. After classifying constraints into first class and second class, the canonical quantization is carried out. We consider the difference of the corresponding physical states between unimodular gravity and general relativity.

The modified XY model is a modification of the XY model by the addition of a half-periodic term. The modified Goldstone model is a regular and continuum version of the modified XY model. The former admits a vortex molecule, that is, two half-quantized vortices connected by a domain wall, as a regular topological soliton solution to the equation of motion, while the latter admits it as a singular configuration. Here, we define the ${\mathbb{Z}}_n$ modified XY and Goldstone models as the $n=2$ case to be the modified XY and Goldstone models, respectively. We exhaust all stable and metastable vortex solutions for $n=2$, 3 and find a vortex confinement transition from an integer vortex to a vortex molecule of $n$ $1/n$-quantized vortices, depending on the ratio between the term of the XY model and the modified term. We find that, for the case of $n=3$, a rod-shaped molecule is the most stable, while a $\mathsf{Y}$-shaped molecule is metastable. We also construct some solutions for the case of $n=4$. The vortex confinement transition can be understood in terms of the $\mathbb{C}/{\mathbb{Z}}_n$ orbifold geometry.

We obtain rotation laws for axially symmetric, self-gravitating and stationary fluids around spinning black holes. They reduce—in the Newtonian limit—to monomial rotation curves. For spinless black holes, one obtains in the first post-Newtonian (1PN) approximation the hitherto known results, that can be interpreted as the geometric dragging and material antidragging. We find new 1PN effects, that are due to spins of black holes.

The dynamical mass of galaxies and the Newtonian acceleration generated from the baryons have been found to be strongly correlated. This correlation is known as “mass discrepancy-acceleration relation.” Further investigations have revealed a tighter relation—“radial acceleration relation” (RAR)—between the observed total acceleration and the (Newtonian) acceleration produced by the baryons. So far, modified gravity theories have remained more successful than $\mathrm{\Lambda }\mathrm{CDM}$ to explain these relations. However, a recent investigation has pointed out that, when RAR is expressed as a difference between the observed acceleration and the expected Newtonian acceleration due to baryons (which has been called the “halo acceleration relation”), it provides a stronger test for modified gravity theories and dark matter hypothesis. Extending our previous work [K. Dutta and T. Islam, Phys. Rev. D 98, 124012 (2018).], we present a case study of modified gravity theories, in particular Weyl conformal gravity and Modified Newtonian Dynamics, using recent inferred acceleration data for the Milky Way. We investigate how well these theories of gravity and the RAR scaling law can explain the current observation.

We present a thorough analysis of the cosmological perturbations in generalized massive gravity. This is an extension of de Rham–Gabadadze–Tolley theory where the translation invariance in the Stückelberg field space is broken. This allows the mass parameters to be promoted to functions of the Stückelberg fields. We consider an exact cosmological background in this theory and study the stability of perturbations. We derive conditions to avoid ghost, gradient and tachyonic instability. The cosmology is an extension of the self-accelerating branch of the constant mass parameter theory, but now all five massive graviton polarizations propagate. For concreteness, we consider a minimal version of the theory where cosmology undergoes an accelerated expansion at late times and show that the perturbative stability is preserved for a range of parameters.