We study non-Abelian fields in the context of very special relativity (VSR). For this, we define the covariant derivative and the gauge field gauge transformations, both of them involving a fixed null vector $n_{\mu }$, related to the VSR breaking of the Lorentz group to the Hom(2) or Sim(2) subgroups. As in the Abelian case, the gauge field becomes massive. Moreover, we show that the VSR gauge transformations form a closed algebra. We then write actions coupling the gauge field to various matter fields (bosonic and fermionic). We mention how we can use the spontaneous symmetry-breaking mechanism to give a flavor-dependent VSR mass to the gauge bosons. Finally, we quantize the model using the Becchi-Rouet-Stora-Tyutin formalism to fix the gauge. The model is renormalizable and unitary and for non-Abelian groups, asymptotically free.

We present an analytical study of continuum $4d$ $SU(2)$ gauge-Higgs models with a single Higgs field with fixed length in either the fundamental or adjoint representation. We aim at analytically probing the renowned predictions of Fradkin and Shenker on the phase diagram in terms of confinement versus Higgs behavior, obtained for the lattice version of the model. We work in the Landau version of the ’t Hooft $R_{\xi }$ gauges in which case we can access potential nonperturbative physics related to the existence of the Gribov copies. In the fundamental case, we clearly show that in the perturbative regime of small gauge coupling constant $g$ and large Higgs vacuum expectation value (vev) $\nu$, there is a Higgs phase with Yukawa gauge boson propagators without Gribov effects. For a small value of the Higgs vev $\nu$ and/or large $g$, we enter a region with Gribov-type propagators that have no physical particle interpretation: the gauge bosons are as such confined. The transition between both behaviors is found to be continuous. In the adjoint case, we find evidence of a more drastic transition between the different behaviors for the propagator of the off-diagonal gauge bosons, whereas the “photon,” i.e. the diagonal component of the gauge field, displays a propagator of the Gribov-type. In the limit of infinite Higgs condensate, we show that a massless photon is recovered. We compare our findings with those of Fradkin and Shenker as well as with more recent numerical lattice simulations of the fundamental Higgs model. We also carefully discuss in which region of the parameter space $(\nu ,g)$ our approximations are trustworthy.

We revisit the problem of computing the self-force on a scalar charge moving along an eccentric geodesic orbit around a Schwarzschild black hole. This work extends previous scalar self-force calculations for circular orbits, which were based on a regular “effective” point-particle source and a full 3D evolution code. We find good agreement between our results and previous calculations based on a ($1+1$) time-domain code. Finally, our data visualization is unconventional: we plot the self-force through full radial cycles to create “self-force loops,” which reveal many interesting features that are less apparent in standard presentations of eccentric-orbit self-force data.

Analytic formulas reproducing the warm dark matter (WDM) cosmological spectra are obtained for WDM particles decoupling in and out of thermal equilibrium; these formulas provide the initial data for WDM nonlinear structure formation. We compute and analyze the corresponding WDM overdensities and compare them to the cold dark matter (CDM) case. We consider the ratio of the WDM to CDM spectrum and the ratio of the WDM to CDM overdensities: They turn out to be self-similar functions of $k/k_{1/2}$ and $R/R_{1/2}$, respectively, with $k_{1/2}$ and $R_{1/2}$ being the wavenumber and length where the WDM spectrum and overdensity are one-half of the respective CDM magnitudes. Both $k_{1/2}$ and $R_{1/2}$ show scaling as powers of the WDM particle mass $m$, while the self-similar functions are independent of $m$. The WDM spectrum sharply decreases around $k_{1/2}$ with respect to the CDM spectrum, while the WDM overdensity slowly decreases around $R_{1/2}$ for decreasing scales with respect to the CDM one. The nonlinear regions where WDM structure formation takes place are shown and compared to those in CDM: The WDM nonlinear structures start to form later than in CDM, and as a general trend, decreasing the DM particle mass delays the onset of the nonlinear regime. The nonlinear regime starts earlier for smaller objects than for larger ones; smaller objects can form earlier both in WDM and CDM. We compute and analyze the differential mass function $dN/dM$ for WDM at redshift $z$ in the Press-Schechter approach. The WDM suppression effect of small scale structure increases with the redshift $z$. Our results for $dN/dM$ are useful to be contrasted with observations, in particular, for $4\lesssim z\lesssim 12$. We perform all of these studies for the most popular WDM particle physics models. Contrasting them to observations should give the value of the WDM particle mass within the keV scale.

We perform an unbiased search of the origin of the recently observed 28 events above $\sim 30\mathrm{TeV}$ in the IceCube neutrino observatory, assuming that these are (apart from the atmospheric background) of astrophysical origin produced by photohadronic interactions. Instead of relying on the normalization of the neutrino flux, we demonstrate that spectral shape and flavor composition can be used to constrain or identify the source class. In order to quantify our observations, we use a model where the target photons are produced by the synchrotron emission of coaccelerated electrons, and we include magnetic field effects on the secondary muons, pions, and kaons. We find that the lack of observed events with energies much larger than PeV points towards sources with strong magnetic fields, which do not exhibit a direct correlation between highest cosmic ray and neutrino energies. While the simplest active galactic nuclei models with efficient proton acceleration plausibly describe the current data at about the $3\sigma$ confidence level, we show that IceCube can rule out that the observed neutrinos stem from the sources of the ultrahigh-energy cosmic rays with a factor of 10 increased statistics at more than $5\sigma$ if the current observations are confirmed. A possible caveat are sources with strong magnetic fields and high Lorentz factors, such as magnetic energy dominated gamma-ray bursts.

Mergers of binary neutron stars create conditions of supranuclear density $n\gtrsim n_{\mathrm{nuc}}\simeq 0.17{\mathrm{fm}}^{-3}$ and moderate temperature $50\lesssim T\lesssim 90\mathrm{MeV}$. These events thus probe a sensitive region of the density-temperature phase diagram of QCD matter. We study photon production by the QCD conformal anomaly for a signal of a possible transition to quark degrees of freedom during the merger. We discuss energy loss due to photon radiation as a cooling mechanism that is sensitive to the bulk viscosity and thermal conductivity of the quark matter.

We discuss the appearance of quark matter in neutron star cores, focusing on the possibility that the recent observation of a very heavy neutron star could constrain free parameters of quark matter models. For that, we use the equation of state derived with the field correlator method, extended to the zero temperature limit, whereas for the hadronic phase we use the equation of state obtained within both the nonrelativistic and the relativistic Brueckner-Hartree-Fock many-body theory. We find a strong dependence of the maximum mass both on the value of the $q\overline{q}$ interaction $V_1$ and on the gluon condensate $G_2$, for which we introduce a dependence on the baryon chemical potential ${\mu }_B$. We find that the maximum masses are consistent with the observational limit for not too small values of $V_1$.

The next generation of large-scale weakly interacting massive particle direct detection experiments have the potential to go beyond the discovery phase and reveal detailed information about both the particle physics and astrophysics of dark matter. We report here on early results arising from the development of a detailed numerical code modeling the proposed DARWIN detector, involving both liquid argon and xenon targets. We incorporate realistic detector physics, particle physics, and astrophysical uncertainties and demonstrate to what extent two targets with similar sensitivities can remove various degeneracies and allow a determination of dark matter cross sections and masses while also probing rough aspects of the dark matter phase-space distribution. We find that, even assuming dominance of spin-independent scattering, multiton-scale experiments still have degeneracies that depend sensitively on the dark matter mass, and on the possibility of isospin violation and inelasticity in interactions. We find that these experiments are best able to discriminate dark matter properties for dark matter masses less than around 200 GeV. In addition, and somewhat surprisingly, the use of two targets gives only a small improvement (aside from the advantage of different systematics associated with any claimed signal) in the ability to pin down dark matter parameters when compared with one target of larger exposure.

The most recent LHC data have provided a considerable improvement in the precision with which various Higgs production and decay channels have been measured. Using all available public results from ATLAS, CMS and the Tevatron, we derive for each final state the combined confidence level contours for the signal strengths in the ($\mathrm{\text{gluon fusion}}+\mathrm{\text{top-quark}}$ pair associated production) versus ($\mathrm{\text{vector boson fusion}}+$ associated production with vector bosons) space. These “combined signal strength ellipses” can be used in a simple, generic way to constrain a very wide class of new physics models in which the couplings of the Higgs boson deviate from the Standard Model prediction. Here, we use them to constrain the reduced couplings of the Higgs boson to up-quarks, down-quarks/leptons and vector boson pairs. We also consider new physics contributions to the loop-induced gluon-gluon and photon-photon couplings of the Higgs, as well as invisible/unseen decays. Finally, we apply our fits to some simple models with an extended Higgs sector, in particular to two-Higgs-doublet models of Type I and Type II, the inert doublet model, and the Georgi-Machacek triplet Higgs model.

We comparatively analyze the flavor-changing neutral current process of ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$ in the standard model as well as the topcolor-assisted technicolor model using the form factors calculated via light cone QCD sum rules in full theory. In particular, we calculate the decay width, branching ratio and lepton forward-backward asymmetry related to this decay channel. We compare the results of the topcolor-assisted technicolor model with those of the standard model and debate how the results of the topcolor-assisted technicolor model depart from the standard model predictions. We also compare our results on the branching ratio and differential branching ratio with recent experimental data provided by CDF and LHCb Collaborations.

We calculate the effective Polyakov line action corresponding to SU(2) lattice gauge theory on a ${16}^3\times 4$ lattice via the “relative weights” method. We consider a variety of lattice couplings, ranging from $\beta =1.2$ in the strong-coupling domain to $\beta =2.3$ at the deconfinement transition, in order to study how the effective action evolves with $\beta$. Comparison of Polyakov line correlators computed in the effective theory and the underlying gauge theory is used to test the validity of the effective action for $\beta >1.4$, while for $\beta =1.2$, 1.4 we can compare our effective action to the one obtained from a low-order strong-coupling expansion. Very good agreement is found at all couplings. We find that the effective action is given by a simple expression bilinear in the Polyakov lines. The range of the bilinear term, away from strong coupling, grows rapidly in lattice units as $\beta$ increases.

We calculate the Polyakov loop susceptibilities in the SU(3) lattice gauge theory using the Symanzik improved gauge action on different-sized lattices. The longitudinal and transverse fluctuations of the Polyakov loop, as well as that of its absolute value, are considered. We analyze their properties in relation to the confinement-deconfinement phase transition. We also present results based on simulations of ($2+1$)-flavor QCD on ${32}^3\times 8$ lattice using highly improved staggered quark action by the HotQCD collaboration. The influences of fermions on the Polyakov loop fluctuations are discussed. We show that ratios of different susceptibilities of the Polyakov loop are sensitive probes for critical behavior. We formulate an effective model for the Polyakov loop potential and constrain its parameters from existing quenched lattice data including fluctuations. We emphasize the role of fluctuations to fully explore the thermodynamics of pure gauge theory within an effective approach.

The impact-parameter dependent color glass condensate (b-CGC) dipole model is based on the Balitsky-Kovchegov nonlinear evolution equation and improves the Iancu-Itakura-Munier dipole model by incorporating the impact-parameter dependence of the saturation scale. Here we confront the model to the recently released high precision combined Hadron Electron Ring Accelerator (HERA) data and obtain its parameters. The b-CGC results are then compared to data at small $x$ for the structure function, the longitudinal structure function, the charm structure function, exclusive vector meson ($J/\psi$, $\varphi$, and $\rho$) production and deeply virtual Compton scattering. We also compare our results with the impact-parameter dependent saturation (IP-Sat) model. We show that most features of inclusive deep inelastic scattering and exclusive diffractive data, including the $Q^2$, $W$, $|t|$, and $x$ dependence, are correctly reproduced in both models. Nevertheless, the b-CGC and the impact-parameter dependent saturation (IP-Sat) models give different predictions beyond the current HERA kinematics, namely for the structure functions at very low $x$ and high virtualities $Q^2$, and for the exclusive diffractive vector meson and deeply virtual Compton scattering production at high $t$. This can be traced back to the different power-law behavior of the saturation scale in $x$ and to a different impact-parameter $b$ dependence of the saturation scale in these models. Nevertheless, both models give approximately similar saturation scales $Q_S<1\mathrm{GeV}$ for the proton in HERA kinematics, and also both models lead to the same conclusion that the typical impact parameter probed in the total ${\gamma }^{*}p$ cross section is about $b\approx 2–3{\mathrm{GeV}}^{-1}$. Our results provide a benchmark for further investigation of QCD at small $x$ in heavy ion collisions at RHIC and the LHC and also at future experiments such as an electron-ion collider and the LHeC.

One- and two-jet observables of dimension-7 Higgs-gluon coupling operators are studied as probes of possible deviations from the top-loop induced gluon-Higgs coupling. We discuss the case of both a scalar as well as a pseudoscalar Higgs boson and show that higher order operators can give visible deviations from Standard Model distribution shapes.

We present a novel scheme where Dirac neutrinos are realized even if lepton number violating Majorana mass terms are present. The setup is the Randall-Sundrum framework with bulk right-handed neutrinos. Bulk mass terms of both Majorana and Dirac type are considered. It is shown that massless zero mode solutions exist when the bulk Dirac mass term is set to zero. In this limit, it is found that the effective 4D small neutrino mass is primarily of Dirac nature, with the Majorana-type contributions being negligible. Interestingly, this scenario is very similar to the one known with flat extra dimensions. Neutrino phenomenology is discussed by fitting both charged lepton masses and neutrino masses simultaneously. A single Higgs localized on the IR brane is highly constrained, as unnaturally large Yukawa couplings are required to fit charged lepton masses. A simple extension with two Higgs doublets is presented, which facilitates a proper fit for the lepton masses.

The flavor evolution of neutrinos emitted by a supernova (SN) core is strongly affected by the refractive effects associated with the neutrino-neutrino interactions in the deepest stellar regions. Till now, all numerical studies have assumed the axial symmetry for the “multi-angle effects” associated with the neutrino-neutrino interactions. Recently, it has been pointed out in Raffelt, Sarikas, and Seixas [Phys. Rev. Lett. 111, 091101 (2013)] that if this assumption is removed, a new multi-azimuthal-angle (MAA) instability emerges in the flavor evolution of the dense SN neutrino gas, in addition to the one caused by multi-zenith-angle effects. Inspired by this result, for the first time we numerically solve the nonlinear neutrino propagation equations in SN, introducing the azimuthal angle as an angular variable in addition to the usual zenith angle. We consider simple energy spectra with an excess of ${\nu }_e$ over ${\overline{\nu }}_e$. We find that even starting with a complete axial symmetric neutrino emission, the MAA effects would lead to significant flavor conversions in normal mass hierarchy, in cases otherwise stable under the only multi-zenith-angle effects. The final outcome of the flavor conversions, triggered by the MAA instability, depends on the initial asymmetry between ${\nu }_e$ and ${\overline{\nu }}_e$ spectra. If it is sufficiently large, final spectra would show an ordered behavior with spectral swaps and splits. Conversely, for small flavor asymmetries flavor decoherence among angular modes develops, also affecting the flavor evolution in the inverted mass hierarchy.

In the CERN NA63 Collaboration we address the question of the potential inadequacy of the commonly used Migdal formulation of the Landau-Pomeranchuk-Migdal (LPM) effect by measuring the photon emission by 20 and 178 GeV electrons in the range of 100 MeV–4 GeV, in targets of low-density polyethylene, C, Al, Ti, Fe, Cu, Mo, and, as a reference target, Ta. For each target and energy, a comparison between simulated values based on the LPM suppression of incoherent bremsstrahlung is shown, taking multiphoton effects into account. For these targets and energies, we find that Migdal’s theoretical formulation is adequate to a precision of better than about 5%, irrespective of the target substance.

We report a measurement of the branching fraction of the exclusive charmless semileptonic decay $B^{+}\to \omega {\ell }^{+}\nu$, where $\ell$ is either an electron or a muon. We use samples of $B^{+}$ mesons tagged by a reconstructed charmed semileptonic decay of the other $B$ meson in the event. The measurement is based on a data set of $426.1{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collisions at a center-of-mass energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ storage rings. We measure a branching fraction of $\mathcal{B}(B^{+}\to \omega {\ell }^{+}\nu )=(1.35\pm 0.21\pm 0.11)\times {10}^{-4}$, where the uncertainties are statistical and systematic, respectively. We also present measurements of the partial branching fractions in three bins of $q^2$, the invariant-mass squared of the lepton-neutrino system, and we compare them to theoretical predictions of the form factors.

A new test of Lorentz invariance in the weak interactions has been made by searching for variations in the decay rate of spin-polarized ${}^{20}\mathrm{Na}$ nuclei. This test is unique to Gamow-Teller transitions, as was shown in the framework of a recently developed theory that assumes a Lorentz symmetry breaking background field of tensor nature. The nuclear spins were polarized in the up and down direction, putting a limit on the amplitude of sidereal variations of the form $|({\Gamma }_{\mathrm{up}}-{\Gamma }_{\mathrm{down}})|/({\Gamma }_{\mathrm{up}}+{\Gamma }_{\mathrm{down}})<3\times {10}^{-3}$. This measurement shows a possible route toward a more detailed testing of Lorentz symmetry in weak interactions.