High Energy Physics - Phenomenology

Ipp, Andreas;Leuthner, Markus;Müller, David I.;Schlichting, Soeren;Singh, Pragya

doi: 10.48550/arXiv.2212.09363pmid: N/A

Abstract: We extend the weak field approximation for the Glasma beyond the boost-invariant approximation, which allows us to compute rapidity-dependent observables in the early stages of heavy-ion collisions. We show that in the limit of small fields, the weak field approximation agrees quantitatively with non-perturbative lattice simulations. Furthermore, we demonstrate that the rapidity profile of the transverse pressure is determined by longitudinal color correlations within the colliding nuclei.

Bruggisser, Sebastian;van Dyk, Danny;Westhoff, Susanne

doi: 10.48550/arXiv.2212.02532pmid: N/A

Abstract: We constrain the flavor structure of Wilson coefficients in the Standard Model Effective Field Theory (SMEFT) from data. In the SMEFT, new physics effects in couplings of up-type and down-type quarks are related through the Cabibbo-Kobayashi-Maskawa mixing matrix. We exploit this relation to pin down potential new sources of flavor symmetry breaking in a global analysis of high- and low-energy data from the LHC, LEP, and $b$ factory experiments. We demonstrate the power of such an analysis by performing a combined fit of effective four-quark and two-quark couplings contributing to a large set of flavor, top-quark, electroweak, and dijet observables. All four sectors are needed to fully resolve the flavor structure of the four-quark couplings without leaving blind directions in the parameter space. Although we work in the framework of minimal flavor violation, our strategy applies as well to other flavor patterns, like $U(2)$ flavor symmetry or leptoquark scenarios.

Lyubovitskij, Valery E.;Schmidt, Ivan

doi: 10.48550/arXiv.2212.04340pmid: N/A

Abstract: Quantum chromodynamics (QCD) rigorously predicts the existence of both nonperturbative intrinsic and perturbative extrinsic heavy quark contents of nucleons. In this article we discuss the heavy quark electroproduction on protons induced by the Fock states $|uud+g\rangle$ of three valence quarks in the proton and a nonperturbative gluon, and the $|uud+Q\bar Q\rangle$ non-perturbative state of three valence quarks and a heavy quark-antiquark pair. The first one gives the perturbative contribution when the gluon produces a heavy quark pair, while the second is the intrinsic part, and they produce amplitude interference. We use nonperturbative light-front wavefunctions for these Fock states, which are computed using the color-confining light-front holographic QCD theory. Due to interference of the amplitudes corresponding to the intrinsic and extrinsic heavy quark contribution to the proton a novel $Q$ vs. $\bar Q$ asymmetry emerges in the differential cross section of the electroproduction off a proton $d^2\sigma_{e^-p}/(dx dQ^2)$. Our analysis provides new insights into the physics of intrinsic heavy quark phenomena in QCD at the amplitude level.

Salvio, Alberto

doi: 10.48550/arXiv.2212.09755pmid: N/A

Abstract: A dark photon is predicted by several well-motivated Standard Model extensions and UV completions. Here the most general effective field theory up to dimension-six operators describing the interactions of a massless dark photon with all Standard Model particles is considered. This captures the predictions of a generic model featuring this type of vector boson at sufficiently low energies. In such framework the thermal production rate of dark photons is computed at leading order, including the contributions of all SM particles. The corresponding cosmological yield of the dark photon and its contribution to the effective number of neutrinos are also calculated. These predictions satisfy the current observational bounds and will be tested by future measurements.

Ghosh, Rituparna;Mukhopadhyaya, Biswarup

doi: 10.48550/arXiv.2212.11688pmid: N/A

Abstract: The Georgi-Machacek model, introducing a complex and a real scalar triplet as additional components of the electroweak symmetry breaking sector, enables substantial triplet contributions to the weak gauge boson masses, subject to the equality of the complex and the real triplet vacuum expectation values (vev) via a custodial SU(2) symmetry. We present an updated set of constraints on this scenario, from collider data (including those from 137/139~fb$^{-1}$ of luminosity at the Large Hadron Collider), available data on the 125-GeV scalar, indirect limits and also theoretical restrictions from vacuum stability and unitarity. It is found that some bounds get relaxed, and the phenomenological potential of the scenario is more diverse, if the doubly charged scalar in the spectrum can decay not only into two like-sign $W$'s but also into one or two singly charged scalars. Other interesting features are noticed in a general approach, such as substantial $\gamma\gamma$ and $Z\gamma$ branching ratios of the additional custodial singlet scalar, and appreciable strength of the trilinear interaction of a charged scalar, the $W$ and the $Z$. Finally,, we take into account the possibility of custodial SU(2) breaking, resulting in inequality of the real and the complex scalar vevs which too in principle may allow large triplet contribution to weak boson masses. Illustrative numerical results on the modified limits and predictions are presented, once more taking into account all the constraints mentioned above.

Zhao, Shuai

doi: 10.48550/arXiv.2212.00825pmid: N/A

Abstract: We outline an approach to calculate the transverse-momentum-dependent distribution of linearly polarized gluons inside an unpolarized hadron on the lattice with the help of large momentum effective theory. To achieve this purpose, we propose calculating a Euclidean version of the degree of polarization for a fast-moving hadron on the lattice, which is ultraviolet finite, and no soft function subtraction is needed. It indicates a practical way to explore the distribution of the linearly polarized gluons in a proton and the linearly polarized gluon effects in hadron collisions on the lattice.

Poncelet, Rene

doi: 10.48550/arXiv.2212.06019pmid: N/A

Abstract: NNLO QCD corrections to the production and decay of top-quark pairs allow performing precision phenomenology in inclusive and fiducial phase spaces. State-of-the-art predictions for top-quark pair production and their comparison to recent collider data are discussed.

Matute, Ernesto A.

doi: 10.1142/S0217732322501966pmid: N/A

Abstract: Neutrino flavor mixing is explained within the recently proposed low-scale minimal linear seesaw model of neutrino mass generation, a variant of the standard linear seesaw led by a Dirac pair of extra sterile neutrinos which is odd under a discrete $Z_2$ symmetry and has a mass at or below the GeV scale. The tri-bimaximal mixing and its deviations are derived straightforwardly on the basis of the symmetry between $\mu$ and $\tau$ flavors, without introducing non-abelian discrete flavor symmetries in the first place.

Kar, Arpan;Kumar, Tanmoy;Roy, Sourov;Zupan, Jure

doi: 10.48550/arXiv.2212.04647pmid: N/A

Abstract: Relativistic axions produced in decays of ${\mathcal O}(10^{-7}-10^{-2}$ $\text{eV})$ dark matter (DM) partially convert to photons after traversing the galactic magnetic field, giving rise to a signal observable by the Square Kilometer Array (SKA) radio telescope. We show that for axions lighter than a few $\times$ $10^{-13}$ eV a 100\,h SKA observation of the local dwarf galaxy Seg I would probe parameter space not constrained by stellar cooling and cosmological observations, with sensitivity several orders of magnitude better than the planned dedicated axion dark matter search experiments. We quantify the uncertainties in the SKA sensitivity projections due to two effects that enhance the photon flux: the presence of turbulent magnetic fields inside the galaxy, and the Bose enhancement of the DM decays to axions, where the latter, in particular, warrants further study.

Richardson, Thomas R.;Schindler, Matthias R.;Springer, Roxanne P.

doi: 10.48550/arXiv.2212.13049pmid: N/A

Abstract: We present a method for ordering two-nucleon interactions based upon their scaling with the number of QCD colors, $N_c$, in the limit that $N_c$ becomes large. Available data in the two-nucleon sector shows general agreement with this ordering, indicating that the method may be useful in other contexts where data is less readily available. However, several caveats and potential pitfalls can make the large-$N_c$ ordering fragile and/or vulnerable to misinterpretation. We discuss the application of the large-$N_c$ analysis to two- and three-nucleon interactions, including those originating from weak and beyond-the-standard-model interactions, as well as two-nucleon external currents. Finally, we discuss some open questions in the field.