A recent preprint by Cheipesh et al. pointed out that the zero-point motion of tritium atoms bound to graphene may blur the measured energies of $\beta$ electrons. Smearing due to zero point motion is well known. Such an effect features in studies of the $\beta$ spectrum expected in experiments like KATRIN using diatomic tritium. The recent preprint may, however, challenge new planned experiments seeking to discover the cosmic neutrino background (CNB) neutrinos (and/or other neutrinos of masses smaller than 0.1 eV), which plan to use tritium adsorbed onto graphene or other materials. Our paper clarifies these issues and examines the more general problem of smearing induced by quantum uncertainty. We find that the effect of Cheipesh et al. is reduced considerably. The importance of the chemical evolution of the ${}^3\mathrm{H}$ atom hosting the tritium nucleus into a tightly bound neutral ${}^3\mathrm{He}$ atom is emphasized. We estimate the excess blurring caused by the dense spectrum near the lowest state of the graphene or other hosts of the tritium atom, generated by the electronic response to the “sudden” escape of the $\beta$ electron. Our analysis suggests yet larger effects and difficulties facing many experiments searching for small mass neutrinos. We speculate on a possible experimental setup, which could minimize quantum broadening.

The accumulated energy density of the excited entropy modes in multiple field inflationary scenarios can play the role of dark matter. In the usual case of a flat field space without any turning trajectory, only light superhorizon entropy modes can be excited through the gravitational instability. In the case of a negatively curved field space, we show that subhorizon entropy modes can be excited as well through the tachyonic instability induced by the negative curvature of the field space. The latter, which is known as the geometrical destabilization mechanism, allows for the production of entropy modes with masses larger than or at the order of the Hubble expansion rate during inflation, leading to a new dark matter scenario. Due to the contribution of subhorizon modes, the corresponding spectral density has a peak at a scale smaller than its counterpart in the models based on a flat field space. This difference makes our model observationally distinguishable.

The cosmic ray flux at the lowest energies, $\lesssim 10\mathrm{GeV}$, is modulated by the solar cycle, inducing a time variation that is expected to carry over into the atmospheric neutrino flux at these energies. Here we estimate this time variation of the atmospheric neutrino flux at five prospective underground locations for multitonne scale dark matter detectors (CJPL, Kamioka, LNGS, SNOlab, and SURF). We find that between solar minimum and solar maximum, the normalization of the flux changes by $\sim 30\%$ at a high-latitude location such as SURF, while it changes by a smaller amount, $\lesssim 10\%$, at LNGS. A dark matter detector that runs for a period extending through solar cycles will be most effective at identifying this time variation. This opens the possibility to distinguish such neutrino-induced nuclear recoils from dark matter-induced nuclear recoils, thus allowing for the possibility of using timing information to break through the “neutrino floor.”

The existence of light sterile neutrinos, as predicted in several models, can help to explain a number of observations starting from dark mater to recent anomalies in short baseline experiments. In this paper, we consider two models—left-right symmetric Zee model and extended seesaw model—that can naturally accommodate the presence of light sterile neutrinos in the eV to MeV mass scale. We perform a detailed study on the neutrinoless double beta decay process which receives major contributions from diagrams involving these light sterile neutrinos. Considering a number of theoretical and experimental constraints, including light neutrino masses and mixings, unitarity of the mixing matrix, etc., we compare our predicted values of the half-life of neutrinoless double beta decay with the experimental limits. This can put significant constraints on the neutrino mass, active-sterile neutrino mixing, and several other important parameters in these models.

We present the first calculation of the $x$ dependence of the isovector transversity generalized parton distributions (GPDs) for the proton within lattice QCD. We compute the matrix elements with nonlocal operators containing a Wilson line. The calculation implements the Breit symmetric frame. The proton momenta are chosen as 0.83, 1.25, and 1.67 GeV, and the values of the momentum transfer squared are 0.69 and $1.02{\mathrm{GeV}}^2$. These combinations include cases with zero and nonzero skewness. The calculation is performed using one ensemble of twisted-mass fermions with a clover term: two degenerate-mass light quarks, a strange quark, and a charm quark. The lattice results are renormalized nonperturbatively and finally matched to the light-cone GPDs using one-loop perturbation theory within the framework of large-momentum effective theory. The final GPDs are given in the $\overline{\mathrm{MS}}$ scheme at a scale of 2 GeV. In addition to the individual GPDs, we form the combination of the transversity GPDs that is related to the transverse spin structure of the proton. Finally, we extract the lowest two moments of the GPDs and draw a number of important qualitative conclusions.

We study the correlation between the quark spin and orbital angular momentum inside the pion meson. Similar to the case inside the nucleon, the longitudinal spin-orbit correlation $C_z^{q/\pi }$ in the pion meson can be expressed in terms of the corresponding generalized parton distributions (GPDs) and generalized transverse momentum distributions (GTMDs). This provides new information about the spin structure of the pion. Using the wave functions of the pion in the light-cone quark model and the overlap representation for GPDs and GTMDs, we present the analytical results for the quark longitudinal spin-orbit correlation. We find that the GPD approach and the GTMD approach lead to the same results. The numerical results are also obtained, showing that the correlation in the pion is antialigned. In addition, we compare $C_z^{q/\pi }$ from the GPD approach and the GTMD approach, with $x$ and the transverse momentum $k_T$ unintegrated.

We investigate the screening masses of neutral pions and sigma mesons in hot and magnetized quark matter in the framework of a two-flavor lattice-improved Nambu–Jona-Lasinio (NJL) model with a magnetic-field-dependent coupling constant, which is determined by utilizing the results from lattice QCD simulations. Since such a model can well reproduce inverse magnetic catalysis (IMC), by comparing with the standard NJL model, we systemically analyze the impacts of IMC on the temperature and magnetic field dependences of the longitudinal and transverse screening masses of the chiral partners, i.e., ${\pi }^0$ and $\sigma$ mesons, as well as the screening mass differences between them. Particularly, it is found that the $eB$ dependences of two alternative (pseudo)critical temperatures for the chiral transition defined by $\sigma -{\pi }^0$ meson screening mass differences are consistent with that defined by the quark condensate.

We describe the determination of the longitudinal structure function $F_L$ at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) approximations, using Laplace transform techniques, into the parametrization of $F_2(x,Q^2)$ and its derivative with respect to $\ln Q^2$ at low values of the Bjorken variable $x$. The obtained results are comparable with others by considering the effect of the charm quark mass to the longitudinal structure function, which leads to rescaling the variable for $n_f=4$. Numerical calculations and comparison with H1 data demonstrate that the suggested method provides reliable $F_L(x,Q^2)$ at small $x$ in a wide range of $Q^2$ values and can be applied as well in analyses of ultrahigh energy processes with cosmic neutrinos. The obtained longitudinal structure functions with and without the LHeC simulated uncertainties [CERN-ACC-Note-2020-0002, P. Agostini et al. (LHeC Collaboration and FCC-he Study Group), J. Phys. G 48, 110501 (2021).] are compared with the H1 Collaboration data [V. Andreev et al. (H1 Collaboration), Eur. Phys. J. C 74, 2814 (2014) and F. D. Aaron et al. (H1 Collaboration), Eur. Phys. J. C 71, 1579 (2011)] and with the results from the CT18 [T.-J. Hou et al., Phys. Rev. D 103, 014013 (2021)] parametrization model at NLO and NNLO approximations.

During recent years, the study of exotic hadrons including tetraquarks and pentaquarks has attracted a lot of interest, and more studies are in progress experimentally and theoretically. It is well known that at sufficiently large transverse momentum the dominant production mechanism for standard heavy hadrons (mesons/baryons) is actually the fragmentation so that the same mechanism is also proposed for the production of heavy exotic hadrons. This work is the first attempt to study the direct fragmentation of a heavy quark into ground state heavy tetraquarks in leading order of perturbative QCD. In this regard, we will present an analytical expression for the fragmentation production of neutral hidden flavor tetraquarks $(Qq\overline{Q}\overline{q})$ which includes most of the kinematical and dynamical properties of the process.

Population studies of stellar-mass black hole binaries have become major players in gravitational-wave astronomy. The underlying assumptions are that the targeted source parameters refer to the same quantities for all events in the catalog and are included when modeling selection effects. Both these points have so far been neglected when estimating the orientations of the black hole spins. In particular, the detector-frame gravitational-wave frequency used to define frequency-dependent quantities (e.g., 20 Hz) introduces an inconsistent reference between events at the population level. We solve both issues by modeling binary black hole populations and selection effects at past time infinity, corresponding to the well-defined reference frequency of 0 Hz. We show that, while current gravitational-wave measurement uncertainties obfuscate the influence of reference frequency in population inference, ignoring spins when estimating selection effects leads to an overprediction of spin alignment in the underlying astrophysical distribution of merging black holes.

We classify radial timelike geodesic motion of the exterior nonextremal Kerr spacetime by performing a taxonomy of inequivalent root structures of the first-order radial geodesic equation, using a novel compact notation and by implementing the constraints from polar, time, and azimuthal motion. Four generic root structures with only simple roots give rise to eight nongeneric root structures when either one root becomes coincident with the horizon, one root vanishes, or two roots becomes coincident. We derive the explicit phase space of all such root systems in the basis of energy, angular momentum, and Carter’s constant and classify whether each corresponding radial geodesic motion is allowed or disallowed from the existence of polar, time, and azimuthal motion. The classification of radial motion within the ergoregion for both positive and negative energies leads to six distinguished values of the Kerr angular momentum. The classification of null radial motion and near-horizon extremal Kerr radial motion are obtained as limiting cases and compared with the literature. We explicitly parametrize the separatrix describing root systems with double roots as the union of the following three regions that are described by the same quartic respectively obtained when (1) the pericenter of bound motion becomes a double root, (2) the eccentricity of bound motion becomes zero, and (3) the turning point of unbound motion becomes a double root.

In this paper we develop the formalism for the stochastic approach to inflation at all order in slow-roll parameters. This is done by including the momentum and Hamiltonian constraints into the stochastic equations. We then specialize to the widely used Starobinski approximation where interactions between IR and UV modes are neglected. We show that, whenever this approximation holds, no significant deviations are observed when comparing the two-point correlation functions (power spectrum) calculated with stochastic methods, to the ones calculated with the Quantum Field Theory (QFT) approach to linear theory. As a by-product, we argue that: (i) the approaches based on the Starobinski approximation, generically, do not capture any loop effects of the quantum scalar-gravity system; (ii) correlations functions can only be calculated in the linear theory regimes; thus, no nonperturbative statistics can be extracted within this approximation, as commonly claimed.

It has been known that a nonperfect fluid that accounts for dissipative viscous effects can evade a highly anisotropic chaotic mixmaster approach to a singularity. Viscosity is often simply parametrized in this context, so it remains unclear whether isotropization can really occur in physically motivated contexts. We present a few examples of microphysical manifestations of viscosity in fluids that interact either gravitationally or, for a scalar field for instance, through a self-coupling term in the potential. In each case, we derive the viscosity coefficient and comment on the applicability of the approximations involved when dealing with dissipative nonperfect fluids. Upon embedding the fluids in a cosmological context, we then show the extent to which these models allow for isotropization of the universe in the approach to a singularity. We first do this in the context of expansion anisotropy only, i.e., in the case of a Bianchi type-I universe. We then include anisotropic 3-curvature modeled by the Bianchi type-IX metric. It is found that a self-interacting scalar field at finite temperature allows for efficient isotropization, whether in a Bianchi type-I or type-IX spacetime, although the model is not tractable all the way to a singularity. Mixmaster chaotic behavior, which is well known to arise in anisotropic models including anisotropic 3-curvature, is found to be suppressed in the latter case as well. We find that the only model permitting an isotropic singularity is that of a dense gas of black holes.

Spin-dependent fifth forces are associated with particles beyond the standard model. In particular, light pseudoscalar bosons mediate long-range forces, allowing mass to interact with spins. The search of these interactions can be performed by periodically varying the distance between a source mass and a spin ensemble, in order to modulate the force intensity and detect it with precision magnetometry techniques. In our setup the force arises from room temperature lead masses and is detected in a paramagnetic crystal at 4.2 K, whose magnetization is monitored by a superconducting quantum interference device (SQUID)-based magnetometer with the sensitivity of $53\mathrm{aT}/\sqrt{\mathrm{H}\mathrm{z}}$. Our measurement places the most stringent constraints on spin-mass interactions in the ranges 1 cm to 10 m and 10 to 300 km, with couplings $g_p^e{g}_s^N\le 5.7\times {10}^{-32}$ and $g_p^e{g}_s^e\le 1.6\times {10}^{-31}$ at 95% C.L., improving existing limits up to more than 2 orders of magnitude. We show that this experimental technique may be further leveraged to explore a vast region of the fifth force’s parameter space, with an interaction range longer than a few centimeters.

In B. K. Sahoo, B. P. Das, and H. Spiesberger, Phys. Rev. D 103, L111303 (2021), we had reported an improved calculation of the nuclear spin-independent parity violating electric dipole transition amplitude ($E{1}_{\mathrm{PV}}$) for the $6s{{}^{2}S}_{1/2}-7s{{}^{2}S}_{1/2}$ transition in ${}^{133}\mathrm{Cs}$ by employing a relativistic coupled-cluster theory. In a recent Comment, Roberts and Ginges have raised questions about our calculation of the so-called Core contribution to $E{1}_{\mathrm{PV}}$. Our result for this contribution does not agree with theirs, but is in agreement with results from previous calculations where this contribution is given explicitly. In our Reply, we explain in detail the validity of the evaluation of our core contribution. We emphasize that the Main, Core and Tail contributions have been treated on an equal footing in our work unlike the sum-over-states calculations. We also address their concerns about our approximate treatment of the contributions from the QED corrections, which was not the aim of our work, but was carried out for completeness. Nonetheless, conclusion of our above-mentioned paper is not going to affect if we replace our estimated QED contribution to $E{1}_{\mathrm{PV}}$ by earlier estimation.

In a recent paper, Sahoo, Das, and Spiesberger, Phys. Rev. D 103, L111303 (2021), a calculation of the parity violating $6S-7S$ E1 amplitude in Cs is reported, claiming an uncertainty of just 0.3%. In this Comment, we point out that key contributions have been omitted, and the theoretical uncertainty has been significantly underestimated. In particular, the contribution of missed QED radiative corrections amounts to several times the claimed uncertainty.

We investigate the scalar resonances in the processes $D^0\to {\pi }^0{\pi }^0{\pi }^0,{\pi }^0{\pi }^0\eta ,{\pi }^0\eta \eta$ based on the chiral unitary approach for the final state interaction. We start from singly Cabibbo-suppressed production diagrams which provide a primary quark pair to hadronize two pseudoscalar mesons in the $D^0$ decays. The resonances $f_0(500)$, $f_0(980)$, and $a_0(980)$ are dynamically produced from the final state interactions of the meson pairs. In our results, the experimental data for the ${\pi }^0\eta$ invariant mass spectrum of the $D^0\to {\pi }^0\eta \eta$ decay can be described well. We also make the predictions for the ${\pi }^0{\pi }^0$ invariant mass spectrum of the $D^0\to {\pi }^0{\pi }^0{\pi }^0$ decay, where the $f_0(980)$ can be found, and for the ${\pi }^0{\pi }^0$, ${\pi }^0\eta$ invariant mass spectra of the $D^0\to {\pi }^0{\pi }^0\eta$ decay, where the states $f_0(500)$, $f_0(980)$, and $a_0(980)$ appear. Furthermore, the branching ratios of each decay channel are predicted. We expect more accurate measurements of these decays to better understand the nature of the states $f_0(500)$, $f_0(980)$, and $a_0(980)$.

We extend the theoretical framework used to describe the $T_{cc}$ state as a molecular state of $D^{*}D$ and make predictions for the $D^{*}{D}^{*}$ and $D_s^{*}{D}^{*}$ systems, finding that they lead to bound states only in the $J^P=1^{+}$ channel. Using input needed to describe the $T_{cc}$ state, basically one parameter to regularize the loops of the Bethe-Salpeter equation, we find bound states with bindings of the order of MeV and similar widths for the $D^{*}{D}^{*}$ system, while the $D_s^{*}{D}^{*}$ system develops a strong cusp around the threshold.

We investigate the massive Schwinger model in $d=1+1$ dimensions using bosonization and the nonperturbative functional renormalization group. In agreement with previous studies we find that the phase transition, driven by a change of the ratio $m/e$ between the mass and the charge of the fermions, belongs to the two-dimensional Ising universality class. The temperature and vacuum angle dependence of various physical quantities (chiral density, electric field, entropy density) are also determined and agree with results obtained from density matrix renormalization group studies. Screening of fractional charges and deconfinement occur only at infinite temperature. Our results exemplify the possibility to obtain virtually all physical properties of an interacting system from the functional renormalization group.

We calculate the ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c^{*}(2595)l\nu$ and ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c^{*}(2625)l\nu$ form factors and decay rates for all possible $b\to cl\overline{\nu }$ four-Fermi interactions in and beyond the Standard Model (SM), including nonzero charged lepton masses and terms up to order $\mathcal{O}({\alpha }_s,1/m_{c,b})$ in the heavy quark effective theory (HQET). We point out a subtlety involving the overcompleteness of the representation of the spin-parity $1/2^{+}\to 3/2^{-}$ antisymmetric tensor form factors, relevant also to other higher excited-state transitions, and present a general method for the counting of the physical form factors for any hadronic transition matrix element and their matching onto HQET. We perform a preliminary fit of a simple HQET-based parametrization of the ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c^{*}$ form factors at $\mathcal{O}({\alpha }_s,1/m_{c,b})$ to an existing quark model, providing preliminary predictions for the lepton universality ratios $R({\mathrm{\Lambda }}_c^{*})$ beyond the SM. Finally, we examine the possible incompatibility of recent lattice QCD results with expectations from the heavy quark expansion and available experimental data.