Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userImpact of a light stabilized radion in supernovae cooling
88
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
In the Randall-Sundrum model where the Standard Model fields are confined to the TeV brane located at the orbifold point $theta = pi$ and the gravity peaks at the Planck brane located at $theta = 0$, the stabilized modulus (radion) field is required to stabilize the size of the fifth spatial dimension. It can be produced copiously inside the supernova core due to nucleon-nucleon bremstrahlung, electron-positron and plasmon-plasmon annihilations, which then subsequently decays to neutrino-antineutrino pair and take away the energy released in SN1987A explosion. Assuming that the supernovae cooling rate $dot{varepsilon} le 7.288times 10^{-27} rm{GeV}$, we find the lower bound on the radion vev $vphi sim 9.0$ TeV, 2.2 TeV and 0.9 TeV corresponding to the radion mass $m_phi = 5$ GeV, 20 GeV and 50 GeV, respectively.
rate research
Read More
We address again the old problem of calculating the radion effective potential in Randall-Sundrum scenarios, with the Goldberger-Wise stabilization mechanism. Various prescriptions have been used in the literature, most of them based on heuristic derivations and then applied in some approximations. We define rigorously a light radion 4D effective action by using the interpolating field method. For a given choice of the interpolating field, defined as a functional of 5D fields, the radion effective action is uniquely defined by the procedure of integrating out the other fields, with the constrained 5D equations of motion always satisfied with help of the Lagrange multipliers. Thus, for a given choice of the interpolating fields we obtain a precise prescription for calculating the effective potential. Different choices of the interpolating fields give different prescriptions but in most cases very similar effective potentials. We confirm the correctness of one prescription used so far on a more heuristic basis and also find several new, much more economical, ways of calculating the radion effective potential. Our general considerations are illustrated by several numerical examples. It is shown that in some cases the old methods, especially in models with strong back-reaction, give results which are off even by orders of magnitude. Thus, our results are important e.g. for estimation of critical temperature in phase transitions.
Recently H. Georgi suggested that a scale invariant unparticle ${mathcal{U}}$ sector with an infrared fixed point at high energy can couple with the SM matter via a higher-dimensional operator suppressed by a high cut-off scale. Intense phenomenological search of this unparticle sector in the collider and flavour physics context has already been made. Here we explore its impact in cosmology, particularly its possible role in the supernovae cooling. We found that the energy-loss rate (and thus the cooling) is strongly dependent on the effective scale LdaU and the anomalous dimension dU of this unparticle theory.
Heavy axion-like particles (ALPs), with masses $m_a gtrsim 100$ keV, coupled with photons, would be copiously produced in a supernova (SN) core via Primakoff process and photon coalescence. Using a state-of-the-art SN model, we revisit the energy-loss SN 1987A bounds on axion-photon coupling. Moreover, we point out that heavy ALPs with masses $m_a gtrsim 100$ MeV and axion-photon coupling $g_{agamma} gtrsim 4 times 10^{-9}$ GeV$^{-1}$ would decay into photons behind the shock-wave producing a possible enhancement in the energy deposition that would boost the SN shock revival.
With the data collected by LHC at 13 TeV, the CMS collaboration has searched for low mass resonances decaying into two photons. This has resulted in the observation of 3 sd excess around 95 GeV, reminiscent of an indication obtained at LEP2 by combining the Higgs boson searches of the four LEP experiments. These observations, marginally significant, motivate the present study which shows how HL-LHC and ILC250 could search for a radion, the lightest new particle predicted within the Randall Sundrum (RS) model. ILC operating at a centre of mass energy of 250 GeV and with an integrated luminosity surpassing LEP2 by three orders of magnitude, could become the ideal machine to study a light radion and to observe, with very high accuracy, how it mixes with the Higgs boson and modifies the various couplings.
A radion in a scenario with a warped extra dimension can be lighter than the Higgs boson, even if the Kaluza-Klein excitation modes of the graviton turn out to be in the multi-TeV region. The discovery of such a light radion would be gateway to new physics. We show how the two-photon mode of decay can enable us to probe a radion in the mass range 60 - 110 GeV. We take into account the diphoton background, including fragmentation effects, and include cuts designed to suppress the background to the maximum possible extent. Our conclusion is that, with an integrated luminosity of 3000 $rm fb^{-1}$ or less, the next run of the Large Hadron Collider should be able to detect a radion in this mass range, with a significance of 5 standard deviations or more.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
