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S. Nussinov

Publications and source records attributed to S. Nussinov.

At least 19 recordsLinked to original sources
arXiv2022

Searches for Baryon Number Violation in Neutrino Experiments: A White Paper

Baryon number conservation is not guaranteed by any fundamental symmetry within the Standard Model, and therefore has been a subject of experimental and theoretical scrutiny for decades. So far, no evidence for baryon number violation has been observed. Large underground detectors have long been used for both neutrino detection and searches for baryon number violating processes. The next generation of large neutrino detectors will seek to improve upon the limits set by past and current experiments and will cover a range of lifetimes predicted by several Grand Unified Theories. In this White Paper, we summarize theoretical motivations and experimental aspects of searches for baryon number violation in neutrino experiments.

hep-ex↗
arXiv2016

A new approach to ultrasensitive gravitational wave detection

We suggest here a method to detect gravitational waves (GW) different from the interferometric approach. It is based on two critical steps: conversion of the GW action into rotational motion and subsequent conversion into electric current. The ability to detect extremely tiny currents empowers this suggested approach in which the gravitational wave moves charges around closed loops. This new method may allow detection of gravitational waves with strain sensitivities beyond the reach of the interferometric approaches.

gr-qc↗
arXiv2015

Superconducting Antenna Concept for Gravitational Wave Radiation

We present an idea for detecting gravitational waves (GWs) by measuring the current induced in a superconducting loop by the rotation of a frame to which it is attached. The frame experiences a torque caused by a GW propagating perpendicular to it because it is made of materials of different density in adjacent quadrants. Superconducting Cooper pair system responds symmetrically to the wave and stays at rest, while the ions of the superconductor are being accelerated by the moving frame. This generates an electric current in the loop which can be measured precisely by sensitive electronics. For that task the antenna consists of two superconducting loops parallel to each other. One of them, the primary loop, rotationally oscillates because of the described reasons, while the second stays at rest. In the oscillating loop the current creates an oscillating magnetic flux. This flux should be compensated due to fluxoid quantization, by the oppositely directed current in the non-moving, secondary loop, in which the ions are at rest, and the Cooper pairs move. We estimate the resulting signal/noise ratio and discuss the signal detectability. Several designs are envisioned, both for terrestrial and for orbital arrangements of the antenna.

cond-mat.supr-con↗
arXiv2014

Some comments on a new type of superconducting gravity wave detector

We have recently suggested a new approach and design of an ultra-sensitive gravity wave detector antenna based on superconductivity. The idea was described in a short paper [1]: http://iopscience.iop.org/1742-6596/507/4/042013, in entries on the arXiv [2]: arXiv:1111.2655, and at various conferences. Here we would like to explain in a more detailed manner the motivation for and the advantages of our approach.

astro-ph.IM↗
arXiv2014

Decoherence due to thermal effects in two quintessential quantum systems

Decoherence effects at finite temperature (T) are examined for two manifestly quantum systems: (i) Casimir forces between parallel plates that conduct along different directions, and (ii) a topological Aharonov-Bohm (AB) type force between fluxons in a superconductor. As we illustrate, standard path integral calculations suggest that thermal effects may remove the angular dependence of the Casimir force in case (i) with a decoherence time set by h/(k_{B} T) where h is Plank's constant and k_{B} is the Boltzmann constant. This prediction may be tested. The effect in case (ii) is due a phase shift picked by unpaired electrons upon encircling an odd number of fluxons. In principle, this effect may lead to small modifications in Abrikosov lattices. While the AB forces exist at extremely low temperatures, we find that thermal decoherence may strongly suppress the topological force at experimentally pertinent finite temperatures. It is suggested that both cases (i) and (ii) (as well as other examples briefly sketched) are related to a quantum version of the fluctuation-dissipation theorem.

quant-ph↗
arXiv2013

Possible Implications of Asymmetric Fermionic Dark Matter for Neutron Stars

We consider the implications of fermionic asymmetric dark matter for a "mixed neutron star" composed of ordinary baryons and dark fermions. We find examples, where for a certain range of dark fermion mass -- when it is less than that of ordinary baryons -- such systems can reach higher masses than the maximal values allowed for ordinary ("pure") neutron stars. This is shown both within a simplified, heuristic Newtonian analytic framework with non-interacting particles and via a general relativistic numerical calculation, under certain assumptions for the dark matter equation of state. Our work applies to various dark fermion models such as mirror matter models and to other models where the dark fermions have self interactions.

astro-ph.CO↗
arXiv2012

Testing Violations of Lorentz Invariance with Cosmic Rays

Cosmic rays are the highest energy particles available for our study and as such serve as excellent probes of the effects of Lorentz Invariance Violations, which are expected to increase with energy. This general paradigm is investigated in this paper by studying the effects of such violations within the Coleman-Glashow model in which each particle species may have its own maximum attainable velocity, even exceeding that of light \textit{in vacuo}. The particular focus here is that the muon neutrino may have the maximum speed exceeding that of light. We show that such an assumption leads to the elongation of the decay lifetime of the pion that increases with energy over and above the time dilation effects. We provide a transparent analytical derivation of the spectral intensities of muon neutrinos and muons generated in the Earth's atmosphere by cosmic rays. In this derivation we not only account for elongation of the pion lifetime, but also for the loss of energy by the neutrinos by radiation of the electron-positron pairs through the Cohen-Glashow process, during their propagation. We then compare the theoretical spectra with observations of neutrinos and muons from large instruments like IceCube and BUST to set a limit of $\sim10^{-13}$ on the fractional excess speed of neutrinos over that of light. We also show that the ratio of the spectral intensities of downward and upward moving neutrinos at various angles constitute a diagnostic exclusively for the Cohen-Glashow process, which may be searched for in the IceCube data set. We conclude the paper with several comments, including those related to improvements of these tests when definite signals of GZK neutrinos will be observed.

hep-ph↗
arXiv2011

Superluminal Neutrinos at OPERA Confront Pion Decay Kinematics

Violation of Lorentz invariance (VLI) has been suggested as an explanation of the superluminal velocities of muon neutrinos reported by OPERA. In this note we show that the amount of VLI required to explain this result poses severe difficulties with the kinematics of the pion decay, extending its lifetime and reducing the momentum carried away by the neutrinos. We show that the OPERA experiment limits $α= (v_ν- c)/c < 4 \times 10^{-6}$. We then take recourse to cosmic ray data on the spectrum of muons and neutrinos generated in the earth's atmosphere to provide a stronger bound on VLI: $(v-c)/c < 10^{-12}$.

hep-ph↗
arXiv2011

Dynamical features of interference phenomena in the presence of entanglement

A "strongly" interacting, and entangling, heavy, non recoiling, external particle effects a significant change of the environment. Described locally, the corresponding entanglement event is a generalized electric Aharonov Bohm effect, that differs from the original one in a crucial way. We propose a gedanken interference experiment. The predicted shift of the interference pattern is due to a self induced or "private" potential difference experienced while the particle is in vacuum. We show that all non trivial Born Oppenheimer potentials are "private" potentials. We apply the Born Oppenheimer approximation to interference states. Using our approach we calculate the relative phase of the external heavy particle as well as its uncertainty throughout an interference experiment /entanglement event. We thus complement the Born Oppenheimer approximation for interference states.

quant-ph↗
arXiv2010

The experimental challenge of detecting solar axion-like particles to test cosmological ALP-photon oscillation hypothesis

We consider possible experimental tests of recent hypotheses suggesting that TeV photons survive the pair production interaction with extragalactic background light over cosmological distances by converting to axion-like particles (ALPs) in galactic magnetic fields. We show that proposed giant ultra-low background scintillation detectors will even have a difficult time reaching the present CAST sensitivity, which is one to two orders of magnitude less sensitive than necessary for a meaningful test of the ALP-photon oscillation hypothesis. Potential alternative tests are briefly discussed.

astro-ph.CO↗
arXiv2009

Can large scintillators be used for solar-axion searches to test the cosmological axion-photon oscillation proposal?

Solar-axion interaction rates in NaI, CsI and Xe scintillators via the axio-electric effect were calculated. A table is presented with photoelectric and axioelectric cross sections, solar-axion fluxes, and the interaction rates from 2.0 to 10.0 keV. The results imply that annual-modulation data of large NaI and CsI arrays, and large Xe scintillation chambers, might be made sensitive enough to probe coupling to photons at levels required to explain axion-photon oscillation phenomena proposed to explain the survival of high-energy photons traveling cosmological distances. The DAMAA/LIBRA data are used to demonstrate the power of the model-independent annual modulation due to the seasonal variation in the earth sun distance.

astro-ph.HE↗
arXiv2008

Density Gradient and Absorption Effects in Gas-Filled Magnetic Axion Helioscopes

The effects of absorption in the gas, and of density variations on the sensitivity of gas-filled solar-axion helioscopes are theoretically investigated. It is concluded that the 10-meter long CAST helioscope, the most sensitive experiment to date is near the limit of sensitivity in axion mass. Increasing the length, gas density, or tilt angle all have negative influences, and will not improve the sensitivity.

astro-ph↗
arXiv2006

An AB effect without closing a loop

We discuss the consequences of the Aharonov-Bohm effect in setups involving several charged particles, wherein none of the charged particles encloses a closed loop around the magnetic flux. We show that in such setups, the AB phase is encoded either in the relative phase of a bi-partite or multi-partite entangled photons states, or alternatively, gives rise to an overall AB phase that can be measured relative to another reference system. These setups involve processes of annihilation or creation of electron/hole pairs. We discuss the relevance of such effects in "vacuum Birefringence" in QED, and comment on their connection to other known effects.

quant-ph↗
arXiv2005

Some Implications of Neutron Mirror Neutron Oscillation

We comment on a recently discussed possibility of oscillations between neutrons and degenerate mirror neutrons in the context of mirror models for particles and forces. It has been noted by Bento and Berezhiani that if these oscillations occurred at a rate of $τ^{-1}_{NN'}\sim sec^{-1}$, it would help explain putative super GKZ cosmic ray events provided the temperature of the mirror radiation is $\sim 0.3-0.4$ times that of familiar cosmic microwave background radiation. We discuss how such oscillation time scales can be realized in mirror models and find that the simplest nonsupersymmetric model for this idea requires the existence of a low mass (30-3000 GeV) color triplet scalar or vector boson. A supersymmetric model, where this constraint can be avoided is severely constrained by the requirement of maintaining a cooler mirror sector. We also find that the reheat temperature after inflation in generic models that give fast $n-n'$ oscillation be less than about 300 GeV in order to maintain the required relative coolness of the mirror sector.

hep-ph↗
arXiv2004

Now You See It, Now You Don't--The Pattern of Production of Certain Resonances

We try to motivate from QCD a pattern of production in various reactions of (non)exotic resonances. A higher penalty for extra q\bar{q} production in e^+ e^- collisions than in collisions with a nucleon target may explain the absence of exotic multi-quark states in e^+ e^- . We also briefly address the doubly-charmed baryons and the utilization of QCD inequalities in connection with possible new hadronic states.

hep-ph↗
arXiv2003

Are there non-strange low-lying penta-quarks and can we understand their width

We argue that the lightest isospin 1/2 partners of the Z^+(1530) s(bar)uudd penta-quark predicted by Diakonov, Petrov and Polyakov are not the N(1710) mixed anti-decuplet states, but the pure non-strange u(bar)(ud)(ud) and d(bar)(ud)(ud) penta-quark states which may lie as low as 1200 MeV. The expected low width of a few MeV of such a putative state may explain why it was missed in phase shift analyzes of pion-nucleon scattering.

hep-ph↗