PeV scale Supersymmetry breaking and the IceCube neutrino flux

The observation of very high energy neutrino events at IceCube has grasped a lot of attention in the fields of both astrophysics and particle physics. It has been speculated that these high energy neutrinos might originate either from purely conventional astrophysical sources or from the late decay of a super heavy (PeV scale) dark matter (DM) particle. In order for decaying DM to be a dominant source of the IceCube high-energy neutrinos, it would require an unusually suppressed value of the coupling of DM to neutrinos. We attempt to explain this small coupling in the context of an $R$-parity conserving minimal supergravity model which has right-handed neutrino superfields. With the main assumptions of super-partner masses at the PeV scale and also a reheating temperature not much larger than the PeV scale, we find in our model several natural order-of-magnitude "miracles", (i) the gravitino is produced via freeze-in as a DM candidate with the correct relic density (ii) the right-handed (RH) sneutrino makes up only a tiny fraction ($10^{-6})$, of the present day energy density of the universe, yet its decay lifetime to the gravitino and neutrinos is such that it naturally predicts the right order-of-magnitude for the IceCube neutrino flux. The long lifetime of the RH sneutrino is explained by the existence of a global $R$-symmetry which is only broken due to supersymmetry breaking effects. Our model also predicts a flux of 100 TeV gamma rays from the decaying RH sneutrino which are within the current observational constraints.Comment: v2: 34 pages, 6 figures, Journal version (published in JHEP

Transport Coefficients of Black MQGP M3-Branes

The SYZ mirror, in the `delocalized limit' of [1], of (M)N (fractional)D3-branes, and wrapped N_f flavor D7-branes in the presence of a black-hole resulting in a non-Kaehler resolved warped deformed conifold (NKRWDC) in [2], was carried out in [3] and resulted in black M3-branes. The uplift, if valid globally(like [4] for fractional D3 branes in conifolds), asymptotes to M5-branes wrapping a two-cycle (homologously an (large) integer sum of two-spheres) in AdS_5xM_6. Interestingly, in the MQGP limit, assuming the deformation > resolution, by estimating the five SU(3) structure torsion (\tau) classes W_{1,2,3,4,5} we show that \tau\in W_4+W_5: 2/3 Re(W^3bar_5)=W^3bar_4 in the UV, implying the NKRWDC locally preserves SUSY. Further, the local T^3 of [3] in the large-r limit and the `MQGP' limit of [3], satisfies the same conditions as the maximal T^2-invariant special Lagrangian three-cycle of T^*(S^3) of [6], partly justifying use of local SYZ mirror symmetry in [3]. Using the Ouyang embedding in the DBI action of a D7-brane or by dimensionally reducing the 11-dimensional EH action to five (R^{1,3},r) dimensions, we then calculate a variety of gauge and metric-perturbation-modes' two-point functions using the prescription of [5], and show: (i) diffusion constant D~1/T, (ii) the electrical conductivity \sigma~T, (iii) the charge susceptibility \chi~ T^2, (iv) [using (i) - (iii)] the Einstein's relation \sigma/\chi=D, is indeed satisfied, (v) the R-charge diffusion constant D_R~1/T, and (vi) the possibility of generating \eta/s=1/4pi from solutions to the vector and tensor mode metric perturbations' EOMs, separately. All results are also valid in the limit of [2].Comment: v4:1+50 pages, correction in torsion classes: type IIB, locally, has SUSY in the U

Towards MQGP

For the Ouyang embedding we calculate the chemical potential mu_C due to a U(1) gauge field on the w.v. of N_f D7-branes wrapped around a 4-cycle in a resolved warped deformed conifold with (M)N (fractional)D3-branes of [1], and show the possible thermodynamical stability up to linear order in the embedding parameter. In the spirit of [2] we obtain the local type IIA mirror using SYZ mirror symmetry near (theta_{1,2},psi)=(,{0,2pi,,4pi}) and then oxidize the same to M theory. We take two limits of this uplift:(i)g_s,g_sN_f,g_sM^2/N,g_s^2M N_f>1 similar to [1] effected by M eps^{-3d/2}, N eps^{-19d},g_s epsn^d,d>0 and eps<=O(0.01);(ii)the `MQGP limit' g_sM^2/N>1 for finite g_s,M, effected by: g_s eps, M eps^{-3d/2},N eps^{-39d},d>0, eps<~1). The second limit is more suited for the study of QGP (See [3]) and can only be addressed in M theory. The uplift gives a black M3-brane solution whose near-horizon geometry near theta_{1,2}=0,pi-branches, preserves 1/8 SUSY. We obtain eta/s=1/4pi for the uplift and the diffusion constant for types IIB/IIA backgrounds comes out to be ~1/T, for both limits. The D=11 SUGRA action up to O(R^4,|G_4|^2) is expected to receive dominant contributions near =0,pi due to poles. Introducing a small-angle cut-off c and using the =c,(pi-c)-local uplift the specific heat from the IR-finite part of the action (c-independent) turns out to be positive indicative of the thermodynamical stability of the uplift. An ALD-gravity-type interpretation can be given to the counter-terms for(i). Its verified that the black M3-brane entropy S r_h^3 from M-theoretic thermodynamical methods and the horizon areas of types IIB/IIA/M3-brane solutions.Comment: 1+58 pages, LaTeX; v4 some minor corrections, results unchange

Extranatural Inflation Redux

The success of a given inflationary model crucially depends upon two features: its predictions for observables such as those of the Cosmic Microwave background (CMB) and its insensitivity to the unknown ultraviolet (UV) physics such as quantum gravitational effects. Extranatural inflation is a well motivated scenario which is insensitive to UV physics by construction. In this five dimensional model, the fifth dimension is compactified on a circle and the zero mode of the fifth component of a bulk $U(1)$ gauge field acts as the inflaton. In this work, we study simple variations of the minimal extranatural inflation model in order to improve its CMB predictions while retaining its numerous merits. We find that it is possible to obtain CMB predictions identical to those of e.g. ${\cal R} + {\cal R}^2$ Starobinsky model of inflation and show that this can be done in the most minimal way by having two additional extra light fermionic species in the bulk, with the same $U(1)$ charges. We then find the constraints that CMB observations impose on the parameters of the model.Comment: Journal version (to appear in Phy. Rev. D

Synergy Between Hubble Tension Motivated Self-Interacting Neutrino and KeV-Sterile Neutrino Dark Matter

The discrepancy between the value of Hubble constant measured by CMB observations and local low-redshift based observations has proposed many solutions which require the existence of Physics beyond Standard Model (SM). One of the interesting solutions is based on considering the strong self-interaction between Standard Model (SM) neutrinos through an additional scalar/vector mediator. Interestingly, the strong self-interaction between SM neutrinos also play an important role in obtaining KeV-sterile neutrino as a viable Dark Matter (DM) candidate through the famous Dodelson-Widrow mechanism. In this work, we have tried to find the synergy between the parameter space of active-sterile neutrino mixing vs mass of sterile neutrino allowed by Hubble tension solution and the requirement of getting KeV-sterile neutrino as DM candidate. Interestingly, we get a large amount of parameter space that is consistent with both the requirements and also free from X-Ray constraints. Finally, we have embedded this scenario in a consistent supersymmetric model of particle physics. In this framework, we have shown that the value of sterile neutrino mass, SM neutrino mass and the required mixing angle can be naturally obtained by considering the supersymmetry breaking scale to be around O(10) TeV. Thus, it would give an interesting testing ground for supersymmetry as well as signatures of Warm Dark Matter (WDM).Comment: v2: 13 pages, 6 figures, 1 Table; Typos fixed and references adde

Explaining the CMS eejjeejj and e missing pT jje\ \rm{missing}\ p_T \ jj excess and leptogenesis in superstring inspired E6E_6 models

We show that superstring inspired $E_6$ models can explain both the recently detected excess $eejj$ and $e\ \rm{missing}\ p_T \ jj$ signals at CMS, and also allow for leptogenesis. Working in a R-parity conserving low energy supersymmetric effective model, we show that the excess CMS events can be produced via the decay of exotic sleptons in Alternative Left-Right Symmetric Model of $E_6$, which can also accommodate leptogenesis at a high scale. On the other hand, either the $eejj$ excess or the $e\ \rm{missing}\ p_T \ jj$ excess can be produced via the decays of right handed gauge bosons, but some of these scenarios may not accommodate letptogenesis as there will be strong $B-L$ violation at low energy, which, along with the anomalous fast electroweak $B+L$ violation, will wash out all baryon asymmetry. Baryogenesis below the electroweak scale may then need to be implemented in these models.Comment: v3: 9 pages, 9 figures, matches published versio