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S. Nussinov

Publications and source records attributed to S. Nussinov.

At least 37 records · Page 2Linked to original sources
arXiv2003

Large Extra Dimensions and Decaying KK Recurrences

We suggest the possibility that in ADD type brane-world scenarios, the higher KK excitations of the graviton may decay to lower ones owing to a breakdown of the conservation of extra dimensional ``momenta'' and study its implications for astrophysics and cosmology. We give an explicit realization of this idea with a bulk scalar field $Φ$, whose nonzero KK modes acquire vacuum expectation values. This scenario helps to avoid constraints on large extra dimensions that come from gamma ray flux bounds in the direction of nearby supernovae as well as those coming from diffuse cosmological gamma ray background. It also relaxes the very stringent limits on reheat temperature of the universe in ADD models.

hep-ph↗
arXiv2003

Some Comments on the Putative $Θ^ +$ (1543) Exotic State

We point out that existing $K^+d$ scattering data available in the PDG (Particle Data Group compilation) suggest some fluctuations in those momentum bins where the (Fermi motion broadened) $Θ^+$[1543] resonance recently indicated in many gamma nuclear reactions and predicted six years ago by Diakonv Petrov and Polyakov might have shown up. The I=0, $J^P={1/2}^+$ P-wave channel should have a universal peak cross section of $\sim 37$ mb at resonance. The smallness of the effect seen in $K^+d$ with the $δσ$ fluctuations being less than 4 mb imply an indirect bound $Γ_{Θ^+} < 6$ MeV, far stronger than the direct gamma-d measurements. This renders the theoretical interpretation of the new state very difficult.

hep-ph↗
arXiv2003

QCD Inequalities and the $D_s(2320)$

We discuss the new state $D_{sJ}(2317)$ discovered by BaBar and demonstrate using QCD inequalities that if indeed the $f_0(980)$ and the new $D_{sJ}(2317)$ ($0^+$) are primarilly made of four quarks that a new I=0 ``$\bar DD$ bound state'' at a mass smaller than 3660 MeV must exist. Observation of such a state will constitute definitive evidence for four-quark states.

hep-ph↗
arXiv2001

Mirror Matter as Self Interacting Dark Matter

It has been argued that the observed core density profile of galaxies is inconsistent with having a dark matter particle that is collisionless and alternative dark matter candidates which are self interacting may explain observations better. One new class of self interacting dark matter that has been proposed in the context mirror universe models of particle physics is the mirror hydrogen atom whose stability is guaranteed by the conservation of mirror baryon number. We show that the effective transport cross section for mirror hydrogen atoms, has the right order of magnitude for solving the ``cuspy'' halo problem. Furthermore, the suppression of dissipation effects for mirror atoms due to higher mirror mass scale prevents the mirror halo matter from collapsing into a disk strengthening the argument for mirror matter as galactic dark matter.

hep-ph↗
arXiv2001

On the $D^0$ -- $D_s$ lifetime difference and $τ\to 7π+ ν_τ$ decays

In this paper we discuss some aspects of inclusive decays of charmed mesons and also decays of the $τ$ lepton into $ν_τ+ 7π$. We find that phase space effects are likely to explain the observed lifetime ratio $τ(D_s^+) / τ(D^0)$ = 1.17. In particular one need not appeal to a large annihilation contribution in the inclusive $D^0$ decay which, being absent in $D_s^+$ decays could also contribute to the enhanced $D^0$ decay rate relative to that of the $D_s^+$. Examining a separate problem, we find that the rate for $τ\to ν_τ+ 7π$ is almost completely dominated by the tiny phase space for the final eight particle state. Using an effective chiral Lagrangian to estimate the matrix element yields a branching ratio into the channel of interest far smaller than the present upper bound.

hep-ph↗
arXiv2001

Effects of Gauge Interactions on Fermion Masses in Models with Fermion Wavefunctions Separated in Higher Dimensions

We consider models that generate hierarchies via the separation of fermion wavefunctions in higher-dimensional spaces. We calculate the effects of gauge interactions between fermions and show that these are important and could help to explain (i) why the heaviest known fermion is a charge 2/3 quark, rather than a charge -1/3 quark or a lepton, (ii) why this fermion has a mass $m_t$ comparable to the electroweak symmetry breaking scale $M_{ew}$, (iii) the patterns $m_t >> m_b > m_τ$ and $m_c >> m_s > m_μ$, and (iv) the smallness of neutrino masses.

hep-ph↗
arXiv2001

Weak and Electromagnetic Nuclear Decay Signatures for Neutrino Reactions in SuperKamiokande

We suggest the study of events in the SuperKamiokande neutrino data due to charged- and neutral-current neutrino reactions followed by weak and/or electromagnetic decays of struck nuclei and fragments thereof. This study could improve the prospects of obtaining evidence for $τ$ production from $ν_μ\to ν_τ$ oscillations and could augment the data sample used to disfavor $ν_μ\to ν_{sterile}$ oscillations.

hep-ph↗
arXiv2000

QCD Inequalities, Large $N_C$ and $ππ$ Scattering Lengths

In this short note we show that (I) in a QCD-like theory with four (rather than two) degenerate flavors $ud u'd'$, the $ππ'$ scattering length is positive (attractive); and (II) in QCD with only two (u,d) degenerate flavors the I=2 (say, $π^+π^+$ hadronic) scattering length is, in the large $N_C$ limit, repulsive. $π(π')$ are the lowest physical states coupling to $J^p = \bar{u}(x)γ_5d(x)$ and $J^{p'} = \bar{u}'(x)γ_5d'(x),$ respectively.

hep-th↗
arXiv2000

On Some Positivity Properties of the Interquark Potential in QCD

We prove that the Fourier transform of the exponential $e^{-\b V(R)}$ of the {\bf static} interquark potential in QCD is positive. It has been shown by Eliott Lieb some time ago that this property allows in the same limit of static spin independent potential proving certain mass relation between baryons with different quark flavors.

hep-th↗
arXiv2000

Correlated Scattering and Cluster Planes

We suggest a new correlation in diffractive production of 2 ``clusters'' $A+B\to A^\ast B^\ast$ with large intrinsic angular momenta for each $A^\ast$ and $B^\ast$ cluster. These correlations are expected in the context of the ``color dipole picture'' for high energy collision and reflect the approximate conservation of dipole direction during the collision. This conservation is in particular manifest when the two dipoles, $\vec d_A$, $\vec d_B$ and the impact vector $\undtilb$ are all parallel. The predicted positive triple correlation is between the momentum transfer $\undtildel$ and the planes of the $A^\ast$ and $B^\ast$ clusters.

hep-ph↗
arXiv2000

SN1987A - a Testing Ground for the KARMEN Anomaly

We show, that SN1987A can serve as an astrophysical laboratory for testing the viability of the assertion that a new massive neutral fermion is implied by the KARMEN data. We show that a wide range of the parameters characterizing the proposed particle is ruled out by the above constraints making this interpretation very unlikely.

hep-ph↗
arXiv1999

TeV Scale Quantum Gravity and Mirror Supernovae as Sources of Gamma Ray Bursts

Mirror matter models have been suggested recently as an explanation of neutrino puzzles and microlensing anomalies. We show that mirror supernovae can be a copious source of energetic gamma rays if one assumes that the quantum gravity scale is in the TeV range. We show that under certain assumptions plausible in the mirror models, the gamma energies could be degraded to the 10 MeV range (and perhaps even further) so as to provide an explanation of observed gamma ray bursts. This mechanism for the origin of the gamma ray bursts has the advantage that it neatly avoids the ``baryon load problem''.

astro-ph↗
arXiv1999

A Decommissioned LHC Model Magnet as an Axion Telescope

The 8.4 Tesla, 10 m long transverse magnetic field of a twin aperture LHC bending magnet can be utilized as a macroscopic coherent solar axion-to-photon converter. Numerical calculations show that the integrated time of alignment with the Sun would be 33 days per year with the magnet on a tracking table capable of $\pm 5^o$ in the vertical direction and $\pm 40^o$ in the horizontal direction. The existing lower bound on the axion-to-photon coupling constant can be improved by a factor between 50 and 100 in 3 years, i.e., $g_{aγγ} \lesssim 9\cdot 10^{-11} GeV^{-1}$ for axion masses $\lesssim$ 1 eV. This value falls within the existing open axion mass window. The same set-up can simultaneously search for low- and high-energy celestial axions, or axion-like particles, scanning the sky as the Earth rotates and orbits the Sun.

astro-ph↗
arXiv1998

Bimaximal Neutrino Mixing and Neutrino Mass Matrix

We show that the bimaximal neutrino mixing pattern suggested by the solar and atmospheric neutrino data can be derived from the maximal, symmetric, four neutrino mixing in the limit that one of the neutrinos is made heavy. Imposing the constraints of no neutrinoless double beta decay and a 20% hot dark matter component of the universe leads to a three neutrino mass matrix recently suggested by Georgi and Glashow. Our result can be useful in constructing theoretical models for the bimaximal pattern. We illustrate this by a simple example.

hep-ph↗
arXiv1998

Gauge Model for Maximal Neutrino Mixing

The recently announced Super-Kamiokande data on atmospheric neutrino oscillation seems to require a maximal mixing between the $ν_μ$ and $ν_τ$ within the conventional three neutrino picture. It is then tempting to suggest as has been done in literature, that the solar neutrino deficit be also understood as resulting from a maximal mixing between $ν_e$ and $ν_μ$. In this letter, we propose a left-right symmetric extension of the standard model where permutation symmetry leads to one of the maximal mixing patterns in a technically natural manner. The double seesaw mechanism gives small Majorana masses for neutrinos needed to understand the atmospheric as well as the solar neutrino puzzles.

hep-ph↗