Rm RH Research Articles

Discrete R -symmetry, various energy scales, and gravitational waves

We present a supersymmetric model where energy scales of a discrete $R$-symmetry breaking ($Z_{6R}$) and cosmic inflation are commonly attributed to the confinement scale of a hidden $Sp(2)$ strong dynamics. Apart from these, SUSY-breaking scale, the Higgsino mass and the right-handed neutrino masses are all shown to stem from $Z_{6R}$ breaking scale inferred from CMB observables. We will show that the model is characterized by the SUSY-breaking soft mass $m_{\rm soft}\simeq100-1000{\rm TeV}$ and the reheating temperature $T_{\rm rh}\simeq10^{9}{\rm GeV}$. Then we discuss how these predictions of the model can be tested with the help of the spectrum of the gravitational wave induced by the short-lived cosmic string present during the reheating era.

Baryogenesis via relativistic bubble expansion

We present a novel baryogenesis mechanism in which the asymmetry is sourced from heavy particles which either gain their mass or are created during bubble expansion in a strong first order phase transition. These particles then decay in a CP and baryon number violating way inside the bubble. The particles are inherently out-of-equilibrium and sufficiently dilute after wall crossing so the third Sakharov condition is easily met. Washout is avoided provided the reheat temperature is sufficiently below the scale of the heavy particles. The mechanism relies on moderate supercooling and relativistic walls which -- in contrast to electroweak baryogenesis -- generically leads to a sizable gravitational wave signal, although in the simplest realisations at frequencies beyond upcoming detectors. We present a simple example model and discuss the restrictions on the parameter space for the mechanism to be successful. We find that high reheat temperatures $T_{\rm RH} \gtrsim 10^{10}$ GeV are generally preferred, whereas stronger supercooling allows for temperatures as low as $T_{\rm RH} \sim 10^{6}$ GeV, provided the vacuum energy density is sufficiently suppressed. We briefly comment on using resonantly enhanced CP violation to achieve even lower scales.

Gravitational production of dark matter during reheating

We consider the direct $s$-channel gravitational production of dark matter during the reheating process. Independent of the identity of the dark matter candidate or its non-gravitational interactions, the gravitational process is always present and provides a minimal production mechanism. During reheating, a thermal bath is quickly generated with a maximum temperature $T_{\rm max}$, and the temperature decreases as the inflaton continues to decay until the energy densities of radiation and inflaton oscillations are equal, at $T_{\rm RH}$. During these oscillations, $s$-channel gravitational production of dark matter occurs. We show that the abundance of dark matter (fermionic or scalar) depends primarily on the combination $T_{\rm max}^4/T_{\rm RH} M_P^3$. We find that a sufficient density of dark matter can be produced over a wide range of dark matter masses: from a GeV to a ZeV.

Implications of the NANOGrav results for inflation

ABSTRACT The NANOGrav pulsar timing array experiment reported evidence for a stochastic common-spectrum process affecting pulsar timing residuals in its 12.5-yr data set, which might be interpreted as the first detection of a stochastic gravitational wave background (SGWB). I examine whether the NANOGrav signal might be explained by an inflationary SGWB, focusing on the implications for the tensor spectral index nT and the tensor-to-scalar ratio r. Explaining NANOGrav while complying with upper limits on r from BICEP2/Keck Array and Planck requires $r \gtrsim {\cal O}(10^{-6})$ in conjunction with an extremely blue tensor spectrum, 0.7 ≲ nT ≲ 1.3. After discussing models, which can realize such a blue spectrum, I show that this region of parameter space can be brought in agreement with big bang nucleosynthesis constraints for a sufficiently low reheating scale, $T_{\rm rh} \lesssim 100\, {\rm GeV} \!-\! 1\, {\rm TeV}$. With the important caveat of having assumed a power-law parametrization for the primordial tensor spectrum, an inflationary interpretation of the NANOGrav signal is therefore not excluded.

Case for decaying spin- 3/2 dark matter

We couple a sterile neutrino sector to a spin-3/2 particle and show that with a Planck reduced coupling, we can obtain a sufficiently long lifetime making the spin-3/2 particle a good dark matter candidate. We show that this dark matter candidate can be produced during inflationary reheating through the scattering of Standard Model particles. The relic abundance as determined by Planck and other experimental measurements is attained for reasonable values of the reheating temperature $T_{\rm RH} \gtrsim 10^{8}$ GeV. We consider two possible gauge invariant couplings to the extended Standard Model. We find a large range of masses are possible which respect the experimental limits on its decay rate. We expect smoking-gun signals in the form of a monochromatic photon with a possible monochromatic neutrino, which can be probed in the near future in IceCube and other indirect detection experiments.

Primordial mass segregation of star clusters: The role of binary stars

Observational results of young star-forming regions suggest that star clusters are completely mass segregated at birth. As a star cluster evolves dynamically, these initial conditions are gradually lost. For star clusters with single stars only and a canonical IMF, it has been suggested that traces of these initial conditions vanish at $\tau_{\rm v}$ between 3 and 3.5 half-mass relaxation times. By the means of numerical models, here we investigate the role of the primordial binary population on the loss of primordial mass segregation. We found that $\tau_{\rm v}$ does not seem to depend on the binary star distribution, yielding $3 < \tau_{\rm v} / t_{\rm rh} < 3.5$. We also conclude that the completely mass segregated clusters, even with binaries, are more compatible with the present-day ONC than the non-segregated ones.

Reheating from F-term inflation on brane and gravitino abundance

The braneworld Randall Sundrum II (RSII) model has been introduced to solve the problem related to the inflation standard scenario. The RSII model is based on a modification in the Friedmann equation by addition of the fifth dimension, which corresponds to energy, called the brane tension $\lambda$. After the inflation end, and when the universe enters in the reheating epoch, the effect of this energy $\lambda$ continues. In this context, we use the F-term model due to a simple superpotential with different forms of the Kahler potential to investigate the brane tension influence on the reheating temperature value $ T_{\rm rh}$. Consequently, we found a large value of $ T_{\rm rh}$, which varies in the range $(1-17) \times 10^{14}$ GeV. Also, we have shown that the variation of temperature value $ T_{{\rm rh}}$ depends on the brane tension and on the inflationary potential. Moreover in the F-term with the linear Kahler potential, the inflaton has a nonzero vacuum expectation value. At the end of inflation, this leads to an overproduction of gravitino which causes the destruction of the successful predictions of nucleosynthesis. In this context, we have shown that the increase in temperature is accompanied by the decrease in gravitino abundance. Therefore the solution of the gravitino overproduction.

The Standard Model Higgs as the origin of the hot Big Bang

If the Standard Model (SM) Higgs is weakly coupled to the inflationary sector, the Higgs is expected to be universally in the form of a condensate towards the end of inflation. The Higgs decays rapidly after inflation - via non-perturbative effects - into an out-of-equilibrium distribution of SM species, which thermalize soon afterwards. If the post-inflationary equation of state of the universe is stiff, $w \simeq +1$, the SM species eventually dominate the total energy budget. This provides a natural origin for the relativistic thermal plasma of SM species, required for the onset of the `hot Big Bang' era. The viability of this scenario requires the inflationary Hubble scale $H_*$ to be lower than the instability scale for Higgs vacuum decay, the Higgs not to generate too large curvature perturbations at cosmological scales, and the SM dominance to occur before Big Bang Nucleosynthesis. We show that successful reheating into the SM can only be obtained in the presence of a non-minimal coupling to gravity $\xi \gtrsim 1$, with a reheating temperature of $T_{\rm RH} \gtrsim \mathcal{O}(10^{10})\xi^{3/2}(H_*/10^{14}{\rm GeV})^2~{\rm GeV}$.

Bounds on very low reheating scenarios after Planck

We consider the case of very low reheating scenarios ($T_{\rm RH}\sim\mathcal{O}({\rm MeV})$) with a better calculation of the production of the relic neutrino background (with three-flavor oscillations). At 95% confidence level, a lower bound on the reheating temperature $T_{\rm RH}>4.1$ MeV is obtained from Big Bang Nucleosynthesis, while $T_{\rm RH}>4.3$ MeV from Planck data for very light ($\sum m_i = 0.06$ eV) neutrinos. If neutrino masses are allowed to vary, Planck data yield $T_{\rm RH}>4.7$ MeV, the most stringent bound on the reheating temperature to date. Neutrino masses as large as 1 eV are possible for very low reheating temperatures.

Implications of theB-mode polarization measurement for direct detection of inflationary gravitational waves

The prospects for direct measurements of inflationary gravitational waves by next generation interferometric detectors inferred from the possible detection of B-mode polarization of the cosmic microwave background are studied. We compute the spectra of the gravitational wave background and the signal-to-noise ratios by two interferometric detectors (DECIGO and BBO) for large-field inflationary models in which the tensor-to-scalar ratio is greater than the order of 0.01. If the reheating temperature $T_{\rm RH}$ of chaotic inflation with the quadratic potential is high ($T_{\rm RH}>7.9\times10^6$ GeV for upgraded DECIGO and $T_{\rm RH}> 1.8\times 10^{6}$ GeV for BBO), it will be possible to reach the sensitivity of the gravitational background in future experiments at $3\sigma$ confidence level. The direct detection is also possible for natural inflation with the potential $V(\phi)=\Lambda^4 [1-\cos(\phi/f)]$, provided that $f>4.2 M_{\rm pl}$ (upgraded DECIGO) and $f>3.6 M_{\rm pl}$ (BBO) with $T_{\rm RH}$ higher than $10^8$ GeV. The quartic potential $V(\phi)=\lambda \phi^4/4$ with a non-minimal coupling $\xi$ between the inflaton field $\phi$ and the Ricci scalar $R$ gives rise to a detectable level of gravitational waves for $|\xi|$ smaller than the order of 0.01, irrespective of the reheating temperature.

Galactic PeV neutrinos from dark matter annihilation

The IceCube Neutrino Observatory has observed highly energetic neutrinos in excess of the expected atmospheric neutrino background. It is intriguing to consider the possibility that such events are probing physics beyond the standard model. In this context, $\mathcal{O}$(PeV) dark matter particles decaying to neutrinos have been considered while dark matter annihilation has been dismissed invoking the unitarity bound as a limiting factor. However, the latter claim was done ignoring the contribution from dark matter substructure, which for PeV Cold Dark Matter would extend down to a free streaming mass of $\mathcal{O}$($10^{-18}$M$_\odot$). Since the unitarity bound is less stringent at low velocities, ($\sigma_{\rm ann}$v)$\leq4\pi/m_\chi^2v$, then, it is possible that these cold and dense subhalos would contribute dominantly to a dark-matter-induced neutrino flux and easily account for the events observed by IceCube. A Sommerfeld-enhanced dark matter model can naturally support such scenario. Interestingly, the spatial distribution of the events shows features that would be expected in a dark matter interpretation. Although not conclusive, 9 of the 37 events appear to be clustered around a region near the Galactic Center while 6 others spatially coincide, within the reported angular errors, with 5 of 26 Milky Way satellites. However, a simple estimate of the probability of the latter occurring by chance is $\sim35\%$. More events are needed to statistically test this hypothesis. PeV dark matter particles are massive enough that their abundance as standard thermal relics would overclose the Universe. This issue can be solved in alternative scenarios, for instance if the decay of new massive unstable particles generates significant entropy reheating the Universe to a slightly lower temperature than the freeze-out temperature, $T_{\rm RH} \lesssim T_{\rm f}\sim4\times10^4$~GeV.

Systems biology of the mitochondrion

The promise of the current era of biological research is to understand the integrated function of biological systems in order to predict and rationally manipulate their behavior, with the ultimate aim of improving human health. In a nutshell, “systems biology” attempts to realize this promise by

Change of variable results for 𝐴_{𝑝}- and reverse Hölder 𝑅𝐻ᵣ-classes

We study conditions under which the map \[ T h , γ w ( x ) = w ( h ( x ) ) | h ′ ( x ) | γ {T_{h,\gamma }}w(x)= w(h(x))|h’(x){|^\gamma } \] maps the Muckenhoupt class A p {A_p} into A q {A_q} and the reverse Hölder class R H r 1 R{H_{{r_1}}} into R H r 2 R{H_{{r_2}}} .

Energy Transfer from the Cyclohexane Singlet – A Pulse Radiolysis Study

AbstractAfter irradiation of liquid cyclohexane with 0.5 ns electron pulses time resolved emission from the cyclohexane singlet state (RH(S1)) was observed. From the decrease of the cyclohexane fluorescence lifetime by adding solutes (S) as alkanes, alkenes and aromatics rate constants of the energy transfer reaction \documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} {{\rm RH}({\rm S}^1) + {\rm S} \to {\rm S}({\rm S}^1) + {\rm RH}} &amp; {(1)} \\ \end{array} $\end{document} were determined. The rate constants of reaction (1) showed a pronounced dependence on the zero‐zero singlet energy difference ΔE of the donor acceptor pair. This k1 vs. ΔE dependence is explained in terms of changes in the Franck‐Condon vibrational overlap factors as well as by a classical model according to Rehm and Weller [1].

Staphylococcal pyomyositis in South Texas

7. Tallett S, MacKenzie C, Middleton P, Kerzner B, and Hamilton R: Clinical, luborutory and epidemiologic features of II viral gnstroenterltis in infants and children, Pediatrics 60:217, 1977. 8. Davidson OP, Bishop RF', Townley RRW, Holmes IH, and Ruck OJ: Importance of a new virus in acute sporadic enteritis in children, Lancet 1:242, 1975. 9. Rodriguez WJ, Kim HW, Arrobio JO, Brandt ED, Chanock RM, Zapikian AZ, Wyatt RO, and Parrott RH: Clinical features of acute gastroenteritis associated with human reovirus-like agent in infants and young children, JPEDIATR 91:188, 1977. 10. Berthiaume L, Alain R, McLaughlin B, and Chagnon A: Use of human gamma-globulin as a first step screening reagent for routine viral infection diagnosis, Proc Microscopic Soc Canada 4:64, 1977.

Product Yield vs Chain Length in γ-Radiolysis of Normal Saturated Fatty Acids

G-Yields of hydrocarbons resulting from60 Co γ-irradiation of normal saturated ${\rm C}_{12}, {\rm C}_{14}, {\rm C}_{16}, {\rm C}_{18}, {\rm C}_{20}$, and ${\rm C}_{30}$ fatty (carboxylic) acids in the crystalline state (and of the C16 and C18 acids in the liquid state) have been determined. ${\rm G}_{{\rm RH}}$ values obtained are in substantial agreement with ${\rm G}_{{\rm CO}_{2}}$ values recently reported for the same substances (excepting the ${\rm C}_{30}$ homolog) by Jones (1-3), and his observation that ${\rm G}_{{\rm CO}_{2}}$ (and hence ${\rm G}_{{\rm RH}}$) is, in general, inversely related to chain length is confirmed. Contrary to earlier claim (4), melissic acid (triacontanoic acid, the ${\rm C}_{30}$ homolog) behaves normally in this regard. Departures from the inverse chain-length relationship are compatible with and may be rationalized by consideration of an additional inverse effect of the density of the irradiated material.

Contributions à l'étude des effets des extrémités dans un générateur à électrodes finies

AbstractThe paper studies the motion of an electro-conductive non-viscous incompressible fluid in a generator of rectangular section having finite electrodes and the rest of its walls being insulating. It is assumed that in the electrodes region a homogeneous magnetic field is applied, whose orientation is normal to the plane of the motion. If the induced magnetic field is neglected, the current function ψ(x, y) and the electrical potential ϕ(x, y) satisfy a system of equations with partial derivatives of the second order, with distributions. Since the system depends upon the parameter λ = RM RH a method of successive approximations is developed, which permits one to obtain the exact solution of the problem. In the last paragraph the results are extended to the case of a generator with N pairs of symmetrical electrodes.

The reaction mechanism of the acid‐catalysed autoxidation of xanthene to xanthylium ion

AbstractThis paper describes an investigation into the kinetics of the autoxidation of xanthene to xanthylium ion and hydrogen peroxide in a perchloric acid/acetic acid mixture at 20°. Apart from acid catalysis, the reaction also shows the characteristics of a free‐radical chain autoxidation. In the mechanism devised to account for the results the key feature is hydrogen abstraction by a protonated peroxy radical with simultaneous production of the stable xanthylium ion: \documentclass{article}\pagestyle{empty}\begin{document}\[{\rm RH + RO}_{\rm 2}{\rm H}\cdot^\oplus\to{\rm R}^\oplus+{\rm H}_{\rm 2}{\rm O}_{\rm 2}+{\rm R}\]\end{document}