Related papers: Hydrogen 21 cm Constraints on the Photon's Spin Sc…
In this article, we study the rare decay process in which a Higgs boson decays into a $Z$ boson and a photon. In the first part of the paper, we analyze the Standard Model (SM) contributions to the corresponding decay width, including the…
Rovibrational transitions in the hydrogen and antihydrogen molecular ions $H_2^+$ and $\overline{H}_2^-$ offer the possibility of testing Lorentz and CPT symmetry to extremely high precision, in principle attaining $O(10^{-17})$. In this…
Imaging the Universe during the first hundreds of millions of years remains one of the exciting challenges facing modern cosmology. Observations of the redshifted 21 cm line of atomic hydrogen offer the potential of opening a new window…
Nuclear-spin conversion in molecular hydrogen is governed by strict symmetry rules that typically require magnetic fields or catalytic surfaces to break. Here we demonstrate that the intrinsic tensor composition of a non-magnetic molecular…
Spin effects in exclusive and inclusive reactions provide an essential new dimension for testing QCD and unraveling hadron structure. Remarkable new experiments from SLAC, HERMES (DESY), and the Jefferson Laboratory present many challenges…
We analyze the collider signals of composite scalars that emerge in certain little Higgs models and models of vectorlike confinement. Similar to the decay of the pion into photon pairs, these scalars mainly decay through anomaly-induced…
Measured and calculated cross sections for spin-exchange between alkali atoms and noble gases (specifically sodium and helium) are used to constrain anomalous spin-dependent forces between nuclei at the atomic scale ($\sim 10^{-8}~{\rm…
In this paper we assume the Higgs is an elementary scalar, and study how new physics could affect its couplings to electroweak gauge bosons. Adding LHC data to LEP data provides new, more stringent limits, particularly when the Higgs to two…
Measurements of the post-reionization 21-cm bispectrum $B_{{\rm HI}}(\mathbf{k_1},\mathbf{k_2},\mathbf{k_3})$ using various upcoming intensity mapping experiments hold the potential for determining the cosmological parameters at a high…
One of the most important parameters in characterizing the Epoch of Reionization, the escape fraction of ionizing photons, $f_\mathrm{esc}$, remains unconstrained both observationally and theoretically. With recent work highlighting the…
We present new analytic calculations of the coupling between ultraviolet resonance photons and the population of the hyperfine states in the light elements (H, D, He3+) which include several previously neglected physical processes. Among…
The measurement of the large scale distribution of neutral hydrogen in the late Universe, obtained with radio telescopes through the hydrogen 21cm line emission, has the potential to become a key cosmological probe in the upcoming years. We…
Lorentz invariance is the fundamental symmetry of Einstein's theory of special relativity, and has been tested to great level of detail. However, theories of quantum gravity at the Planck scale indicate that Lorentz symmetry may be broken…
A significant fraction of pp collisions at the LHC will involve (quasi-real) photon interactions occurring at energies well beyond the electroweak energy scale. Hence, the LHC can to some extend be considered as a high-energy photon-photon…
A rather high Higgs mass, m_h = 126 GeV, suggests that at least a part of the supersymmetric spectrum of the MSSM may live beyond O(1TeV) and hence inaccessible to the LHC. However, there are theoretical and phenomenological reasons…
We demonstrate a weak continuous measurement of the pseudo-spin associated with the clock transition in a sample of Cs atoms. Our scheme uses an optical probe tuned near the D1 transition to measure the sample birefringence, which depends…
Rovibronic molecular hydrogen (H$_2$) transitions at redshift $z_{\rm abs} \simeq 2.659$ towards the background quasar B0642$-$5038 are examined for a possible cosmological variation in the proton-to-electron mass ratio, $\mu$. We utilise…
The possible existence of short-range forces between unpolarized and polarized spin-1/2 particles has attracted the attention of physicists for decades. These forces are predicted in various theories and provide a possible new source for…
By means of the optical metric, we investigate the propagation of a polarized light in an inhomogeneous medium in this paper. We find that the evolution of photons is affected by the spin-spin interaction of photons, besides the spin-orbit…
We obtain new stringent constraints on a light spinless particle phi coupled only to photons at low energies, considering its effects on the extragalactic photon background, the blackbody spectrum of the CMBR and the cosmological abundance…