Sep 12th, 2024
CMS-TOP-23-008
The first measurement of the inclusive and normalised differential cross sections of single top quark production in association with a W boson in proton-proton collisions at a centre-of-mass energy of 13.6 TeV is presented. The data were recorded with the CMS detector at the LHC in 2022, and correspond to an integrated luminosity of 34.7 fb−1. The analysed events contain one muon and one electron in the final state. For the inclusive measurement, multivariate discriminants exploiting the kinematic properties of the events are used to separate the signal from the dominant top quark-antiquark production background. A cross section of 82.3 ± 2.1 (stat) +9.9−9.7 (syst) ± 3.3 (lumi) pb is obtained, consistent with the predictions of the standard model. A fiducial region is defined according to the detector acceptance to perform the differential measurements. The resulting differential distributions are unfolded to particle level and show good agreement with the predictions at next-to-leading order in perturbative quantum chromodynamics.
CMS-TOP-23-008
Signal
Background
CMS-TOP-23-008
CMS-TOP-23-008
S. Prasad et al.
In relativistic heavy-ion collisions, the formation of a deconfined and thermalized state of partons, known as quark-gluon plasma, leads to enhanced production of strange hadrons in contrast to proton-proton (pp) collisions, which are taken as baseline. This observation is known as strangeness enhancement in heavy-ion collisions and is considered one of the important signatures that can signify the formation of QGP. However, in addition to strangeness enhancement, recent measurements hint at observing several heavy-ion-like features in high-multiplicity pp collisions at the LHC energies. Alternatively, event shape observables, such as charged particle multiplicity, transverse spherocity, transverse sphericity, charged particle flattenicity, and relative transverse activity classifiers, can fundamentally separate hard interaction-dominated jetty events from soft isotropic events. These features of event shape observables can probe the observed heavy-ion-like features in pp collisions with significantly reduced selection bias and can bring all collision systems on equal footing. In this article, we present an extensive summary of the strange particle ratios to pions as a function of different event classifiers using the PYTHIA~8 model with color reconnection and rope hadronization mechanisms to understand the microscopic origin of strangeness enhancement in pp collisions and also prescribe the applicability of these event classifiers in the context of strangeness enhancement. Charged-particle flattenicity is found to be most suited for the study of strangeness enhancement, and it shows a similar quantitative enhancement as seen for the analysis based on the number of multi-parton interactions.
O. Gould, I. Ostrovskiy, A. Upreti
Magnetic monopoles (MMs) are well-motivated hypothetical particles whose discovery would symmetrize Maxwell equations, explain quantization of electric charge, and probe the gauge structure of the unified theory. Recent models predict MMs with low masses, reinvigorating searches at colliders. However, most theories predict composite MMs, whose production in parton-parton collisions is expected to be suppressed. The Schwinger process, whereby MM pairs tunnel through the vacuum barrier in the presence of a strong magnetic field, is not subject to this limitation. Additionally, the Schwinger cross section can be calculated nonperturbatively. Together, these make it a golden channel for low-mass MM searches. We investigate the Schwinger production of MMs in heavy-ion collisions at future colliders, in collisions of cosmic rays with the atmosphere, and in decay of magnetic fields of cosmic origin. We find that a next-generation collider would provide the best sensitivity. At the same time, exploiting the infrastructure of industrial ore extraction and Antarctic ice drilling could advance the field at a faster timescale and with only a modest investment. We also propose deploying dedicated MM detectors in conjunction with cosmic ray observatories to directly investigate if the unexplained, highest energy cosmic rays are MMs. Together, the proposed efforts would define the field of MM searches in the next decades.
D.W.P. Amaral et al
We perform the first search for ultralight dark matter using a magnetically levitated particle. A sub-millimeter permanent magnet is levitated in a superconducting trap with a measured force sensitivity of 0.2 fN/√Hz. We find no evidence of a signal and derive limits on dark matter coupled to the difference between baryon and lepton number, B−L, in the mass range (1.10360 - 1.10485) × 10−13 eV/c2. Our most stringent limit on the coupling strength is gB−L ≲ 2.98 × 10−21.
We propose the POLONAISE (Probing Oscillations using Levitated Objects for Novel Accelerometry in Searches of Exotic physics) experiment, featuring short-, medium-, and long-term upgrades that will give us leading sensitivity in a wide mass range and demonstrating the promise of this novel quantum sensing technology in the hunt for dark matter.
T. Maity, C. Boehm
Current ton-scale direct detection experiments have started observing solar neutrinos. In this paper, we probe the weak mixing angle using the latest direct detection data. Utilizing the recent measurement of 8B solar neutrinos through coherent neutrino-nucleus scattering by PandaX-4T, we demonstrate that it can probe the weak mixing angle in a complementary region with an error bar comparable to that of dedicated neutrino experiments. Additionally, we show that the current XENONnT electron recoil data can probe the weak mixing angle through neutrino-electron scattering. This occurs in a momentum transfer region that is more than an order of magnitude smaller than the region probed by atomic parity violation experiments. Our findings show huge scope of probing a Standard Model parameter in an entirely new energy regime through the observation of neutrinos in future direct detection experiments.
REF: XENONnT paper