Standard Model Matter Research Articles

Ultraviolet finite resummation of perturbative quantum gravity

Abstract If the metric is chosen to depend exponentially on the conformal factor, and if one works in a gauge where the conformal factor has the wrong sign propagator, perturbative quantum gravity corrections can be partially resummed into a series of terms each of which is ultraviolet finite. These new terms however are not perturbative in some small parameter, and are not individually BRST invariant, or background diffeomorphism invariant. With appropriate parametrisation, the finiteness property holds true also for a full phenomenologically relevant theory of quantum gravity coupled to (beyond the standard model) matter fields, provided massive tadpole corrections are set to zero by a trivial renormalisation.

Dark branes for dark matter

We propose a setup for the origin of dark matter based on spacetime with a warped extra dimension and three branes: the Planck brane, the TeV brane, at a (few) TeV scale ρT, and a dark brane, at a (sub-)GeV scale ρ1≲100 GeV≪ρT. The Standard Model (SM) is localized in the TeV brane, thus solving the Higgs hierarchy problem, while the dark matter χ, a Dirac fermion with mass mχ<ρ1, is localized in the dark brane. The radion, with mass mr<mχ, interacts strongly [∼mχ/ρ1∼O(1)] with dark matter and very weakly (∼mfρ1/ρT2≪1) with the Standard Model matter f. The generic conflict between the bounds on its detection signatures and its proper relic abundance is avoided as dark matter annihilation is p-wave suppressed. The former is determined by its very weak interactions with the SM and the latter by its much stronger annihilation into radions. Therefore, there is a vast range in the dark matter’s parameter space where the correct relic abundance is achieved consistently with the existing bounds. Moreover, for the dark brane with ρ1≲3 GeV, a confinement/deconfinement first order phase transition, where the radion condensates, produces a stochastic gravitational wave background at the nanohertz frequencies, which can be identified with the signal detected by the Pulsar Timing Array (PTA) experiments. In the PTA window, for 0.15≲mχ≲2 GeV the relic abundance is reproduced and all constraints are satisfied. Published by the American Physical Society 2024

Towards natural and realistic E7 GUTs in F-theory

We consider phenomenological aspects of a natural class of Standard Model-like supersymmetric F-theory vacua realized through flux breaking of rigid E7 gauge factors. Three generations of Standard Model matter are realized in many of these vacua. We further find that many other Standard Model-like features are naturally compatible with these constructions. For example, dimension-4 and 5 terms associated with proton decay are ubiquitously suppressed. Many of these features are due to the group theoretical structure of E7 and associated F-theory geometry. In particular, a set of approximate global symmetries descends from the E7 group, leading to exponential suppression of undesired couplings.

Single phonon detection for dark matter via quantum evaporation and sensing of He3

Dark matter is five times more abundant than ordinary visible matter in our Universe. While laboratory searches hunting for dark matter have traditionally focused on the electroweak scale, theories of low mass hidden sectors motivate new detection techniques. Extending these searches to lower mass ranges, well below 1 GeV/c2, poses new challenges as rare interactions with standard model matter transfer progressively less energy to electrons and nuclei in detectors. Here, we propose an approach based on phonon-assisted quantum evaporation combined with quantum sensors for detection of desorption events via tracking of spin coherence. The intent of our proposed dark matter sensors is to extend the parameter space to energy transfers in rare interactions to as low as a few meV for detection of dark matter particles in the keV/c2 mass range. Published by the American Physical Society 2024

Dark matter from an effective couplings approach

In this work we briefly review dark matter evidence, in the Weakly Interacting Massive Particles (WIMP) paradigm we study the cases of scalar and fermion dark matter candidates. Our study introduces effective couplings between dark matter and Standard Model matter, it is intended as an exercise for academic purposes setting up the required tools for a further analysis. Under the last assumption, we calculate the relic density in order to constrain the model parameter space.

A beyond-the-Standard-Model model without Higgs

In this talk we describe the construction of a putative beyond-the-Standard-Model model where, as a viable alternative to the Higgs scenario, elementary particle masses emerge in a non-perturbative way as a consequence of a sort of “interference” between residual UV chiral breaking effects left behind in the Nambu–Goldstone phase of the theory at a critical value of the Yukawa coupling where chiral symmetry is recovered, and IR features triggered by the phenomenon of spontaneous breaking of (the recovered) chiral symmetry which standardly takes place in a strongly interacting theory. Elementary particle masses are all proportional to the RGI scale of the theory. Thus to get the top quark and the electro-weak boson masses at the desired value one must have ΛRGI≫ΛQCD. This in turn implies that there must exist a new superstrongly interacting sector of fermions (we call them Tera-fermions) gauge invariantly coupled to Standard Model matter with ΛRGI≡ΛT of the order of a few TeVs. We give the expression of the full Lagrangian of a model encompassing quarks, Tera-quarks and W, as well as leptons, Tera-leptons and B gauge bosons when besides strong, Tera-strong and weak interactions, also hypercharge is included. The interest of considering elementary particle physics models with this kind of non-perturbative mass generation mechanism is twofold. First of all, unlike the Standard Model in this scenario elementary particle masses are not free parameters but are determined by the dynamics of the theory. Secondly, some of the conceptual problems of today's formulation of the Standard Model, namely origin of the electroweak scale and naturalness, find a possible solution.

Pulsar timing residual induced by ultralight tensor dark matter

Ultralight boson fields, with a mass around 10-23 eV, are promising candidates for the elusive cosmological dark matter. These fields induce a periodic oscillation of the spacetime metric in the nanohertz frequency band, which is detectable by pulsar timing arrays. In this paper, we investigate the gravitational effect of ultralight tensor dark matter on the arrival time of radio pulses from pulsars. We find that the pulsar timing signal caused by tensor dark matter exhibits a different angular dependence than that by scalar and vector dark matter, making it possible to distinguish the ultralight dark matter signal with different spins. Combining the gravitational effect and the coupling effect of ultralight tensor dark matter with standard model matter provides a complementary way to constrain the coupling parameter α. We estimate α ≲ 10-6 ∼ 10-5 in the mass range m < 5 × 10-23 eV with current pulsar timing array.

Dark matter or regular matter in neutron stars? How to tell the difference from the coalescence of compact objects

The mirror twin Higgs model is a candidate for (strongly-interacting) complex dark matter, which mirrors SM interactions with heavier quark masses. A consequence of this model are mirror neutron stars---exotic stars made entirely of mirror matter, which are significantly smaller than neutron stars and electromagnetically dark. This makes mergers of two mirror neutron stars detectable and distinguishable in gravitational wave observations, but can we observationally distinguish between regular neutron stars and those that may contain some mirror matter? This is the question we study in this paper, focusing on two possible realizations of mirror matter coupled to standard model matter within a compact object: (i) mirror matter captured by a neutron star and (ii) mirror neutron star-neutron star coalescences. Regarding (i), we find that (nonrotating) mirror-matter-admixed neutron stars no longer have a single mass-radius sequence, but rather exist in a two-dimensional mass-radius plane. Regarding (ii), we find that binary systems with mirror neutron stars would span a much wider range of chirp masses and completely different binary Love relations, allowing merger remnants to be very light black holes. The implications of this are that gravitational wave observations with advanced LIGO and Virgo, and x-ray observations with NICER, could detect or constrain the existence of mirror matter through searches with wider model and parameter priors.

Sculpting the Standard Model from low-scale gauge-Higgs-matter E8 grand unification in ten dimensions

The construction and general implications of a model with complete supersymmetric unification of the Standard Model matter content, interactions and families' replication into a single E8 gauge superfield in ten dimensions is presented. The gauge and extended Poincaré symmetries are broken through compactification of the T6/(Z3×Z3) orbifold with Wilson lines, which reduces the original symmetry and matter content into those of the Standard Model plus additional heavier states. Proton decay can be suppressed automatically while the compactification scale may be as low as 109GeV, so that the corresponding GUT-scale physics may be potentially accessible and testable by future collider measurements.

Impact of ATLAS constraints on effective dark matter-standard model interactions with spin-one mediators

We complement a previous work [Fabiola Fortuna et al., Effective field theory analysis of dark matter-standard model interactions with spin one mediators, J. High Energy Phys. 02 (2021) 223.] using an effective field theory framework of dark matter and standard model interactions, with spin-one mediators, exploring a wider dark matter mass range, up to 6.4 TeV. We again use bounds from different experiments: relic density, direct detection experiments, and indirect detection limits from the search of gamma-ray emissions and positron fluxes. Additionally, in this paper we add collider constraints by the ATLAS Collaboration in the monojet analysis. Moreover, here we tested our previous results in the light of the aforementioned ATLAS data, which turns out to be the most restrictive for light dark matter masses (as expected), ${m}_{\mathrm{DM}}&lt;{M}_{Z}/2$. We obtain a larger range of solutions for the operators of dimension 5, OP1 and OP4, where masses above 43 GeV and 30 GeV [except for the $Z$-resonance region, $\ensuremath{\sim}({M}_{Z}\ifmmode\pm\else\textpm\fi{}{\mathrm{\ensuremath{\Gamma}}}_{Z})/2$], respectively, are allowed. In contrast, the operator of dimension 6, OP3, has viable solutions for masses $\ensuremath{\gtrsim}190\text{ }\text{ }\mathrm{GeV}$. For the combination of OP1 and OP3 we obtain solutions (for masses larger than 140 GeV or 325 GeV) that depend on the relative sign between the operators.

Ultraviolet freeze-in dark matter through the dilaton portal

We study a class of models in which the Standard Model (SM) and dark matter (DM) belong to a conformal/scale-invariant theory at high energies. Scale invariance is spontaneously broken at scale $f$, giving rise to a dilaton as the corresponding Goldstone boson. In the low-energy theory, we assume that DM interacts with the SM solely through the dilaton portal, which is suppressed by the conformal breaking scale $f$. For $f\ensuremath{\gg}\mathrm{TeV}$, the portal interactions are extremely weak, resulting in DM not being in thermal equilibrium with the SM. Thus, ultraviolet freeze-in production of DM occurs through the dilaton portal, being most effective at the maximum temperature of the SM bath. The temperature evolution is greatly impacted by the reheating dynamics, which we parametrize using a general equation of state $w$ and temperature at the end of reheating ${T}_{\mathrm{rh}}$. We analyze the implications of the reheating dynamics for DM production in this framework and identify regions of parameter space that result in the observed DM relic abundance for a wide range of DM masses and reheating temperatures for scalar, vector, or fermion DM.

Dark SU(2) Stueckelberg portal

We study the non-abelian $SU(2)_D$ extension of the $U(1)_D$ Stueckelberg portal, which plays a role of the mediator between the Standard Model (SM) and Dark Sector (DS). This portal is specified by the Stueckelberg mechanism for generation of dark gauge boson masses. Proposed $U(1)_D\times SU(2)_D$ Stueckelberg portal has a connection with SM matter fields in analogy with Familon Model. We derive bounds on the couplings of dark portal bosons and SM particles, which govern diagonal and non-diagonal flavor transitions of quarks and leptons.

Gauge Couplings Evolution from the Standard Model, through Pati–Salam Theory, into E8 Unification of Families and Forces

We explore the potential of ultimate unification of the Standard Model matter and gauge sectors into a single E8 superfield in ten dimensions via an intermediate Pati–Salam gauge theory. Through a consistent realisation of a T6/(Z6×Z2×Z2) orbifolding procedure and renormalisation group evolution of gauge couplings, we establish several novel benchmark scenarios for New Physics that are worth further phenomenological exploration.

Masses of Compact (Neutron) Stars with Distinguished Cores

In this paper, the impact of core mass on the compact/neutron-star mass-radius relation is studied. Besides the mass, the core is parameterized by its radius and surface pressure, which supports the outside one-component Standard Model (SM) matter. The core may accommodate SM matter with unspecified (or poorly known) equation-of-state or several components, e.g., consisting of admixtures of Dark Matter and/or Mirror World matter etc. beyond the SM. Thus, the admissible range of masses and radii of compact stars can be considerably extended.

Semidark Higgs boson decays: Sweeping the Higgs neutrino floor

We study exotic Higgs decays $h \to Z X$, with $X$ an invisible beyond the Standard Model (SM) particle, resulting in a semi-dark final state. Such exotic Higgs decays may occur in theories of axion-like-particles (ALPs), dark photons or pseudoscalar mediators between the SM and dark matter. The SM process $h\to Z\nu\bar{\nu}$ represents an irreducible "neutrino floor" background to these new physics searches, providing also a target experimental sensitivity for them. We analyze $h \to Z + \text{invisible}$ searches at the LHC and a future ILC, showing that these exotic Higgs decays can yield sensitivity to unexplored regions of parameter space for ALPs and dark matter models.

Freeze-out forbidden dark matter in the hidden sector in the mass range from sub-GeV to TeV

Kinematically forbidden channels can set the freeze-out dark matter (DM) relic abundance. These channels are described by DM annihilations into heavier states, which vanish at zero temperature limit, but occur at finite temperatures in the early Universe. For the case that the final state of the forbidden channel is scalar mediators that couple to Standard Model (SM) matter through mixing with the SM Higgs, the signals from DM-nucleon interactions and from mediator-related missing energy or displaced vertices could be detected by direct detections and particle physics experiments, respectively. We thus present a study on the simplest secluded vector dark matter model that can exhibit this scenario in the mass range from sub-GeV to TeV. The dark matter resides in the hidden sector, which is in thermal equilibrium with the SM before freeze-out. During freeze-out, the depletion of its density results from its annihilation into two heavier but metastable scalars, where the coupling can be determined by having the correct relic density and constrained by the perturbative unitarity bound. However, much of the allowed parameter space is insensitive to the mixing angle between the hidden scalar and SM Higgs. We find that a more significant mass splitting between DM and the mediator can be allowed only in the sub-GeV region. Moreover, the mass splitting in the TeV region is required to be within the percent level. This model of the forbidden DM interacting with SM particles through the scalar portal is testable in experiments.

Quantum field simulator for dynamics in curved spacetime.

In most cosmological models, rapid expansion of space marks the first moments of the Universe and leads to the amplification of quantum fluctuations1. The description of subsequent dynamics and related questions in cosmology requires an understanding of the quantum fields of the standard model and dark matter in curved spacetime. Even the reduced problem of a scalar quantum field in an explicitly time-dependent spacetime metric is a theoretical challenge2-5, and thus a quantum field simulator can lead to insights. Here we demonstrate such a quantum field simulator in a two-dimensional Bose-Einstein condensate with a configurable trap6,7 and adjustable interaction strength to implement this model system. We explicitly show the realization of spacetimes with positive and negative spatial curvature by wave-packet propagation and observe particle-pair production in controlled power-law expansion of space, using Sakharov oscillations to extract amplitude and phase information of the produced state. We find quantitative agreement with analytical predictions for different curvatures in time and space. This benchmarks and thereby establishes a quantum field simulatorof a new class. In the future, straightforward upgrades offer the possibility to enter unexplored regimes that give further insight into relativistic quantum field dynamics.

Implication of the dark axion portal for the EDM of fermions and dark matter probing with NA64e , NA64μ , LDMX, M3 , and BaBar

The link between ordinary Standard Model (SM) photons and both dark photons and axion-like particles (ALPs) can be introduced through the dark axion portal coupling. Given the dark axion portal setup, in the present paper we refer to the dark photon as the mediator between SM and dark matter (DM) particles, implying that it decays predominantly into a pair of DM fermions. Furthermore, we discuss in detail the implication of the dark axion portal scenario for the lepton (electron and muon) fixed-target experiments. In particular, for the specific fixed-target facility we study the missing-energy signatures of the dark photon production followed by its invisible decay into stable DM particles. We investigate the potential to probe dark axion portal vertices with regarding signatures and derive the expected sensitivities of $\mathrm{NA}64e$, $\mathrm{NA}64\ensuremath{\mu}$, LDMX and ${\mathrm{M}}^{3}$. Moreover, we estimate the expected reach of $\mathrm{NA}64e$ from the projected statistics of the $J/\ensuremath{\psi}$ vector meson invisible decays. We also recast the BABAR monophoton bounds for the specific dark axion portal scenario. In addition, we modify the dark axion portal setup by including in the model both the hadron- and lepton-specific ALP couplings. As a result, we obtain the bounds on the combination of fermion-specific couplings of ALP from the fixed-target experiments. We discuss the implication of the modified dark axion portal scenario for the electric dipole moments (EDMs) of SM fermions. In addition, we derive novel constraints on the combination of the $CP$-violating neutron-specific ALP couplings from the existing bounds on neutron EDMs by taking into account the neutron anomalous magnetic moment.

Quasi-sterile neutrinos from dark sectors. Part I. BSM matter effects in neutrino oscillations and the short-baseline anomalies.

Quasi-sterile neutrinos are a natural consequence of dark sectors interacting with the Standard Model (SM) sector via neutrino- and vector-portals. Essentially, quasi-sterile neutrinos are light dark sector fermions with two generic properties: (i) they mix with the active neutrinos of the SM, and (ii) they are charged under a vector mediator that couples feebly to SM matter. Various interesting phenomenological consequences result from this class of particles. In this article, we investigate one such consequence: new, beyond the SM matter effects that can alter in-medium neutrino oscillations. In particular, for special windows of energy and matter densities, active neutrinos can resonantly oscillate into sterile neutrinos. We take advantage of this feature to build a quasi-sterile neutrino model that can explain the MiniBooNE and LSND anomalies, while remaining compatible with observations from long-baseline reactor- and accelerator-based neutrino experiments. This model is also likely compatible with the recent results reported by the MicroBooNE collaboration (albeit we cannot precisely quantify this claim due to a lack of information in MicroBooNE’s public data releases to date). Implications for solar neutrinos and νe disappearance searches are also briefly discussed.

More on fake GUT

It is remarkable that the matter fields in the Standard Model (SM) are apparently unified into the SU(5) representations. A straightforward explanation of this fact is to embed all the SM gauge groups into a simple group containing SU(5), i.e., the grand unified theory (GUT). Recently, however, a new framework “fake GUT” has been proposed. In this new framework, the apparent matter unification can be explained by a chiral gauge group G, G ⊃ SU(5). We emphasize that the SM matter fields are not necessarily embed- ded into the chiral representations to explain the apparent unification. In this paper, we discuss details of concrete realizations of the fake GUT model. We first study the model based on SU(5) × U(2)H, where SU(3)c in the SM is from SU(5) while SU(2)L× U(1)Y are from the diagonal subgroups of SU(5) × U(2)H. We also extend this model to the one based on a semi-simple group, SU(5) × SU(3)H, so that U(2)H is embedded in SU(3)H. We also show that this framework predicts rather different decay patterns of the proton, compared to the conventional GUT.