Showing papers by "Prateek Agrawal published in 2022"

Some open questions in axion theory

Abstract: Prateek Agrawal, Kim V. Berghaus, JiJi Fan, 4 Anson Hook, Gustavo Marques-Tavares, and Tom Rudelius Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom C.N. Yang Institute for Theoretical Physics, Stony Brook University, NY 11794, USA Department of Physics, Brown University, Providence, RI, 02912, USA Brown Theoretical Physics Center, Brown University, Providence, RI, 02912, U.S.A Maryland Center for Fundamental Physics, University of Maryland, College Park, MD 20742, USA Department of Physics, University of California, Berkeley

Warped Compactifications in Particle Physics, Cosmology and Quantum Gravity

Abstract: Particle physics has evolved in the past decade through evaluating the consequences of experimental measurements as well as exploiting theoretical tools that permit exploration of new model building and cosmological possibilities. Particularly due to insights from the AdS/CFT correspondence, higher-dimensional warped compactifications, in particular, have played a big role in recent developments by allowing a study of regimes of parameters that would otherwise be intractable. Similarly, theoretical developments in quantum gravity benefit from the bigger range of possibilities that can be explored using warped geometry, allowing for constructions of string vacua with positive cosmological constant and for the exploration of entanglement and information transfer in arbitrary dimensions. Puzzles remain in both more phenomenologically oriented and more theoretically oriented contexts which form the basis for a rich research program in the future as well. ar X iv :2 20 3. 07 53 3v 1 [ he pth ] 1 4 M ar 2 02 2

Searching for axion forces with precision precession in storage rings

Abstract: We consider different types of storage rings as precision probes of axion-mediated monopole-dipole forces. We show that current and planned experiments aiming to measure magnetic and electric dipole moments of protons, muons and electrons very precisely may explore new parts of the parameter space beyond existing laboratory bounds and, in some cases, beyond astrophysical constraints. Remarkably, a light axion coupled to muons may explain the FNAL/BNL $(g-2)_\mu$ anomaly as an environmental effect -- the coherent axion field generated by the earth nucleons induces an extra contribution to the anomalous precession frequency of the muon explaining the discrepancy with respect to the SM prediction.

Axion couplings in grand unified theories

Abstract: A bstract We show that the couplings of axions to gauge bosons are highly restricted in Grand Unified Theories where the standard model is embedded in a simple 4D gauge group. The topological nature of these couplings allows them to be matched from the UV to the IR, and the ratio of the anomaly with photons and gluons for any axion is fixed by unification. This implies that there is a single axion, the QCD axion, with an anomalous coupling to photons. Other light axion-like particles can couple to photons by mixing through the QCD axion portal and lie to the right of the QCD line in the mass-coupling plane. Axions which break the unification relation between gluon and photon couplings are necessarily charged under the GUT gauge group and become heavy from perturbative mass contributions. A discovery of an axion to the left of the QCD line can rule out simple Grand Unified models. Axion searches are therefore tabletop and astrophysical probes of Grand Unification.

The Boring Monopole

Abstract: We study false vacuum decays catalysed by metastable magnetic monopoles which act as tunnelling sites with exponentially enhanced decay rates. Metastable monopoles are configurations where the monopole core is in the true vacuum of the scalar potential. The field profiles describing the decay do not have the typically assumed O(3)/O(4)O(3)/O(4) symmetry, thus requiring an extension of the usual decay rate calculation. To numerically determine the saddle point solutions which describe the tunnelling process we use a new algorithm based on the mountain pass theorem. This method can be applied more widely to phase transitions with reduced symmetry, such as decays away from the zero and infinite temperature limits. In our setup monopole-catalysed tunnelling can dominate over the homogeneous false vacuum decay for a wide range of parameters, significantly modify the gravitational wave signal or trigger phase transitions which would otherwise never complete. A single boring monopole in our Hubble patch may determine the lifetime of our current vacuum.

Flavoured $(g-2)_\mu$ with Dark Lepton Seasoning

Abstract: As a joint explanation for the dark matter (DM) problem and the muon $(g-2)$ anomaly, we propose a simplified model of lepton-flavoured complex scalar DM with couplings to both the left- and right-handed leptons of the Standard Model (SM). Both interactions are governed by the same new flavour-violating coupling matrix $\lambda$, however we allow for a relative scaling of the coupling strength. The SM is further extended by two fermion representations, transforming as an $SU(2)_L$ doublet and singlet, respectively, and mediating these interactions. The fermions additionally couple to the SM Higgs doublet via a new Yukawa coupling. To study the model's phenomenology we first investigate constraints from collider searches, flavour experiments, precision tests of the SM, the DM relic density, and direct as well as indirect detection experiments individually. We then perform a combined analysis by demanding that all mentioned constraints are satisfied simultaneously. We use the results of this combined analysis and examine if the model is capable of accommodating the $(g-2)_\mu$ anomaly within its viable parameter space without introducing fine-tuned lepton masses. For all benchmark scenarios we consider, we find that the central value of $\Delta a_\mu^\text{exp}$ can be reached without generating too large corrections to the lepton masses. We hence conclude that this model qualifies as a viable and attractive lepton-flavoured DM model that at the same time solves the $(g-2)_\mu$ anomaly.

TF08 Snowmass Report: BSM Model Building

Abstract: We summarize the state of Beyond the Standard Model (BSM) model building in particle physics for Snowmass 2021, focusing mainly on several whitepaper contributions to BSM model building (TF08) and closely related areas.

Flavoured ( g − 2 ) μ with Dark Lepton Seasoning

Abstract: As a joint explanation for the dark matter (DM) problem and the muon (g − 2) anomaly, we propose a simplified model of lepton-flavoured complex scalar DM with couplings to both the leftand right-handed leptons of the Standard Model (SM). Both interactions are governed by the same new flavour-violating coupling matrix λ, however we allow for a relative scaling of the coupling strength. The SM is further extended by two fermion representations, transforming as an SU(2)L doublet and singlet, respectively, and mediating these interactions. The fermions additionally couple to the SM Higgs doublet via a new Yukawa coupling. To study the model’s phenomenology we first investigate constraints from collider searches, flavour experiments, precision tests of the SM, the DM relic density, and direct as well as indirect detection experiments individually. We then perform a combined analysis by demanding that all mentioned constraints are satisfied simultaneously. We use the results of this combined analysis and examine if the model is capable of accommodating the (g − 2)μ anomaly within its viable parameter space without introducing fine-tuned lepton masses. For all benchmark scenarios we consider, we find that the central value of ∆a μ can be reached without generating too large corrections to the lepton masses. We hence conclude that this model qualifies as a viable and attractive lepton-flavoured DM model that at the same-time solves the (g − 2)μ anomaly. ar X iv :2 21 2. 08 14 2v 1 [ he pph ] 1 5 D ec 2 02 2