High Energy Physics Phenomenology

In a recent paper by N. Santowsky et al. [Phys. Rev. D 102, 056014 (2020)], covariant coupled equations were derived to describe a tetraquark in terms of a mix of four-quark states2q2q¯and two-quark statesqq¯. These equations were expressed in terms of vertices describing the disintegration of a tetraquark into identical two-meson states, into a diquark-antidiquark pair, and into a quark-antiquark pair. We show that these equations are inconsistent as they imply aqq¯Bethe-Salpeter kernel that isqq¯-reducible.

Without excluding the contributions of factorizable Feynman diagrams in the color space to the QCD sum rules by hand, we cannot obtain the conclusion that the factorizable parts of the operator product expansion series cannot have any relationship to the possible tetraquark bound states. The tetraquark couplingsfTare of the orderO(Nc)rather than of the orderO(N0c)in the largeNclimit, the conclusion "a possible exotic tetraquark state may appear only inNc-subleading contributions to the QCD Green functions" is a paradox.

New solutions of the Bargmann-Wigner equations are obtained: free fermion-antifermion pairs, each satisfying Dirac's equation, with parallel momenta and momenta on a plane, produce vectors satisfying Proca's equations. These equations are consistent with Dirac's and Maxwell's equations, as zero-order conditions within a Lagrangian expansion for the U(1)-symmetry quantum field theory. Such vector solutions' demand that they satisfy Maxwell's equations and quantization fix the charge. The current equates the vector field, reproducing the superconductivity London equations, thus, binding and screening conditions. The derived vertex connects to QCD superconductivity and constrains four-fermion interaction composite models.

The strong suppression of high-pTjets in heavy ion collisions is a result of elastic and inelastic energy loss suffered by the jet multi-prong collection of color charges that are resolved by medium interactions. Hence, quenching effects depend on the fluctuations of the jet substructure that are probed by the cone size dependence of the spectrum. In this letter, we present the first complete, analytic calculation of the inclusiveR-dependent jet spectrum in PbPb collisions at LHC energies, including resummation of energy loss effects from hard, vacuum-like emissions occurring in the medium and modeling of soft energy flow and recovery at the jet cone. Both the geometry of the collision and the local medium properties, such as the temperature and fluid velocity, are given by a hydrodynamic evolution of the medium, leaving only the coupling constant in the medium as a free parameter. The calculation yields a good description of the centrality andpTdependence of jet suppression forR=0.4together with a mild cone size dependence, which is in agreement with recent experimental results. Gauging the theoretical uncertainties, we find that the largest sensitivity resides in the leading logarithmic approximation of the phase space of resolved splittings, which can be improved systematically, while non-perturbative modeling of the soft-gluon sector is of relatively minor importance up to large cone sizes.

We present a consistent implementation of weak decays involving an axion or axion-like particle in the context of an effective chiral Lagrangian. We argue that previous treatments of such processes have used an incorrect representation of the flavor-changing quark currents in the chiral theory. As an application, we derive model-independent results for the decaysK???????aand?????e??ν¯eaat leading order in the chiral expansion and for arbitrary axion couplings and mass. In particular, we find that theK???????abranching ratio is almost 40 times larger than previously estimated.

We constrainCP-violating charged and neutral anomalous triple gauge couplings using LHC measurements and projections of diboson and VBFVjjproduction, both with subsequent leptonic decays. For triple gauge couplings involvingWbosons we analyse asymmetries and interpret our results in the SMEFT at dimension-six. For neutral triple gauge couplings, which are dominantly constrained by high transverse-momentum bins, we present the resulting bounds in terms of a general anomalous couplings framework.

Axion-like particles (ALPs), a class of pseudoscalars common to many extensions of the Standard Model, have the capacity to drain energy from the interiors of stars. Consequently, stellar evolution can be used to derive many constraints on ALPs. We study the influence that keV-MeV scale ALPs which interact exclusively with photons can exert on the helium-burning shells of asymptotic giant branch stars, the late-life evolutionary phase of stars with initial masses less than8M??. We establish the sensitivity of the final stellar mass to such energy-loss for ALPs with masses currently permitted by stellar evolution bounds. A semi-empirical constraint on the white dwarf initial-final mass relation (IFMR) derived from observation of double white dwarf binaries is then used to exclude part of a currently unconstrained region of ALP parameter space, the cosmological triangle. The derived constraint relaxes when the ALP decay length becomes shorter than the width of the helium-burning shell. Other potential sources for stellar constraints on ALPs are also discussed.

We consider dark matter which have non-zero electromagnetic form factors like electric/magnetic dipole moments and anapole moment for fermionic dark matter and Rayleigh form factor for scalar dark matter. We consider dark matter massm?>O(MeV)and put constraints on their mass and electromagnetic couplings from CMB and LSS observations. Fermionic dark matter with non-zero electromagnetic form factors can annihilate toe+e??and scalar dark matter can annihilate to2γat the time of recombination and distort the CMB. We analyze dark matter with multipole moments with Planck and BAO observations. We find upper bounds on anapole momentgA<7.163?103GeV??, electric dipole momentD<7.978?10??e-cm, magnetic dipole momentμ<2.959?10??μB, and the bound on Rayleigh form factor of dark matter isg4/?24<1.085?10??GeV??with95%C.L.

The couplings between the neutrinos and exotic fermion can be probed in both neutrino scattering experiments and dark matter direct detection experiments. We present a detailed analysis of the general neutrino interactions with an exotic fermion and electrons at neutrino-electron scattering experiments. We obtain the constraints on the coupling coefficients of the scalar, pseudoscalar, vector, axialvector, tensor and electromagnetic dipole interactions from the CHARM-II, TEXONO and Borexino experiments. For the flavor-universal interactions, we find that the Borexino experiment sets the strongest bounds in the low mass region for the electromagnetic dipole interactions, and the CHARM-II experiment dominates the bounds for other scenarios. If the interactions are flavor dependent, the bounds from the CHARM-II or TEXONO experiment can be avoided, and there are correlations between the flavored coupling coefficients for the Borexino experiment. We also discuss the detection of sub-MeV DM absorbed by bound electron targets and illustrate that the vector coefficients preferred by XENON1T data is allowed by the neutrino experiments.

Dark matter may self-interact through a continuum of low-mass states. This happens if dark matter couples to a strongly-coupled nearly-conformal hidden sector. This type of theory is holographically described by brane-localized dark matter interacting with bulk fields in a slice of 5D anti-de Sitter space. The long-range potential in this scenario depends on a non-integer power of the spatial separation, in contrast to the Yukawa potential generated by the exchange of a single 4D mediator. The resulting self-interaction cross section scales like a non-integer power of velocity. We identify the Born, classical and resonant regimes and investigate them using state-of-the-art numerical methods. We demonstrate the viability of our continuum-mediated framework to address the astrophysical small-scale structure anomalies. Investigating the continuum-mediated Sommerfeld enhancement, we demonstrate that a pattern of resonances can occur depending on the non-integer power. We conclude that continuum mediators introduce novel power-law scalings which open new possibilities for dark matter self-interaction phenomenology.