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Shmuel Nussinov

Publications and source records attributed to Shmuel Nussinov.

At least 19 recordsLinked to original sources
arXiv2025

A Mini Review of some Dark Matter/BSM Physics and a Bit More

There is a vast literature on Dark Matter (DM) with many reviews of specific topics only a small fraction of which will be mentioned. I start with a very brief review of cosmology which underlies much of DM research and some relevant General Relativity (GR). I next discuss Self Interacting Dark Matter (SIDM) models and upper bounds on the mass M(X) of point-like, symmetric DM. This is followed up by some general aspects of DM detection and directional and temporal variations. I discuss DM models tied with BSM physics scenarios including Primordial Black Holes, new physics in the neutrino sector, ultra-light DM and axions.

hep-ph↗
arXiv2025

Searching for hadronic scale baryonic and dark forces at $(g-2)_μ$'s lattice-vs-dispersion front

The anomalous magnetic moment of the muon ($\,a_μ\,$) provides a stringent test of the quantum nature of the Standard Model (SM) and its extensions. To probe beyond the SM physics, one needs to be able to subtract the SM contributions, which consists of a non-perturbative part, namely, the hadronic vacuum polarization (HVP) of the photon. The state of the art is to predominantly use two different methods to extract this HVP: lattice computation, and dispersion relation-based, data-driven method. Thus one can construct different forms of the ``$a_μ$ test" which compares the precise measurement of $a_μ$ to its theory prediction. Additionally, this opens the possibility for another subtle test, where these two ``theory" predictions themselves are compared against each other, which is denoted as the ``HVP-test". This test is particularly sensitive to hadronic scale new physics. Therefore, in this work, we consider a SM extension consisting of a generic, light $\sim(100~{\rm MeV}-1~{\rm GeV})$ vector boson and study its impact on both tests. We develop a comprehensive formalism for this purpose. We find that in the case of data-driven HVP being used in the $a_μ$ test, the new physics contributions effectively cancels for a flavor-universal vector boson. As an illustration of these general results, we consider two benchmark models: i)~the dark photon ($\,A'\,$) and ii)~a gauge boson coupled to baryon-number ($\,B\,$). Using a combination of these tests, we are able to constrain the parameter space of $B$ and $A'$, complementarily to the existing limits. As a spin-off, our preliminary analysis of the spectrum of invariant mass of $3π$ in events with ISR at the $B-$ factories (BaBar, Belle) manifests the value of such a study in searching for $B\to 3π$ decay, thus motivating a dedicated search by experimental collaborations.

hep-ph↗
arXiv2024

Effects of Neutron-Antineutron Transitions in Neutron Stars

We analyze effects of neutron-antineutron transitions in neutron stars, specifically on (i) cooling, (ii) rotation rate, and (iii) for binary pulsars, the increase in the orbital period. We show that these effects are negligibly small.

hep-ph↗
arXiv2022

Constraints on Neutron-Mirror-Neutron Oscillation from Neutron Star Cooling

We address a method of limiting neutron-mirror neutron mixing ($ε_{nn'}$) by analyzing its effect on neutron star (NS) heating. This method employs observational bounds on the surface temperature of NSs to constrain $ε_{nn'}$. It has been suggested that the bound obtained this way is so stringent that it would exclude any discovery of $n-n'$ oscillation in the currently planned terrestrial experiments at various laboratories. This conclusion motivated us to critically analyze this suggestion in more detail. In this note, we point out a very interesting new effect present in nearly exact mirror models, which can significantly affect this bound. The new element is that in nearly exact mirror models there is the mirror analog of $β$ decay, i.e. $n' \to p' + e' + \barν'_e$, which creates a cloud of mirror particles $n'$, $p'$, $e'$, $D'$ and He$'$ inside the NS. The resulting $e'$ can "rob" the energy generated by the $n \to n'$ transition from the NS, via $e-e'$ scattering enabled by the presence of a (minute) millicharge in mirror particles. Such a tiny millicharge on mirror particles is highly likely in these models. This results in energy being emitted as unobserved mirror photons via fast mirror bremsstrahlung, whose effect is to relax the stringent bounds on $ε_{nn'}$.

hep-ph↗
arXiv2022

Neutron-Mirror-Neutron Oscillation and Neutron Star Cooling

It was pointed out in a recent paper that the observed cooling rate of old, cold neutron stars (NS) can provide an upper limit on the transition rate of neutron to mirror neutron ($n-n'$). This limit is so stringent that it would preclude any discovery of $n \to n'$ oscillation in the current round of terrestrial searches for the process. Motivated by this crucially important conclusion, we critically analyze this suggestion and note an interesting new effect present in nearly exact mirror models for $n \to n'$ oscillation, which significantly affect this bound. The new element is the $β$ decay $n' \to p'+ e' +\barν'_{e}$, which creates a cloud of mirror particles $n'$, $p'$, $e'$ and $D'$ inside the NS core. The $e'$ can "rob" the energy generated by the $n \to n'$ transition via $e-e'$ scattering enabled by the presence of a (minute) milli-charge in mirror particles. This energy is emitted as unobserved mirror photons via fast mirror bremsstrahlung leading to a relaxation of this upper limit.

hep-ph↗
arXiv2021

Quantum Induced Broadening- A Challenge For Cosmic Neutrino Background Discovery

A recent preprint by Cheipesh {\it et al.} pointed out that the zero-point motion of Tritium atoms bound to Graphene may blur the measured energies of $β$ electrons. Smearing due to zero point motion is well known. Such an effect features in studies of the $β$ spectrum expected in experiments like KATRIN using diatomic Tritium. The recent preprint may, however, challenge new planned experiments seeking to discover the Cosmic Neutrino Background (CNB) neutrinos (and/or other neutrinos of masses smaller than $0.1$ eV) which plan to use Tritium adsorbed onto Graphene or other materials. Our paper clarifies these issues and examines the more general problem of smearing induced by quantum uncertainty. We find that the effect of Cheipesh {\it et al.} is reduced considerably. The importance of the chemical evolution of the $^{3}$H atom hosting the Tritium nucleus into a tightly bound neutral $^{3}$He atom is emphasized. We estimate the excess blurring caused by the dense spectrum near the lowest state of the Graphene or other hosts of the Tritium atom, generated by the electronic response to the "sudden" escape of the $β$ electron. Our analysis suggests yet larger effects and difficulties facing many experiments searching for small mass neutrinos. We speculate on a possible experimental setup which could minimize quantum broadening.

hep-ph↗
arXiv2020

Dark Matter Clusters and Time Correlations in Direct Detection Experiments

Assuming that dark matter (DM) efficiently clusters on various scales we analyse the possible impact on direct DM searches. For certain sizes and densities of DM clusters, mutual detector-cluster encounters may occur only once a year or every several years leading to the apparent failure of individual experiments searching for DM to discover it. If, however, encounters with Earth size and up to $10^4$ times bigger clusters occur about once a year, then finding time correlations between events in different underground detectors can lead to DM discovery.

hep-ph↗
arXiv2019

Solar luminosity bounds on mirror matter

We present bounds on mirror dark matter scenario derived by using the effect of mirror matter on the luminosity of the Sun. In the perturbative regime where the mirror matter concentration is small relative to the ordinary matter we estimate the heat transfer from ordinary matter to the mirror sector by simple analytic consideration. That amount of heat transfer is radiated via mirror photons and increases the required energy production in order to maintain the observed luminosity. We then present more detailed numerical calculations of the total amount of this energy transfer.

astro-ph.HE↗
arXiv2019

Bounds on Neutron- Mirror Neutron Mixing from Pulsar Timings and Gravitational Wave Detections

The mass loss in putative neutron star to mixed neutron - mirror neutron star transition implies a significant change of orbital period. The precise constancy of the latter can restrict scenarios recently suggested where neutron to mirror neutron mixing occurring in neutron stars, transforms them into mixed stars helping explain the narrow mass distribution observed for pulsars in binary systems. The observation of a very old millisecond pulsar with a mass of 2 solar masses is an additional strong constraint on the above transition.We also note that the observed gravitational waves signals from neutron-neutron stars merger constrain the neutron to mirror neutron transitions inside neutron stars. These considerations exclude a large region in the $ε'$, $δm'$ plane of the neutron-mirror neutron mixing and mass

hep-ph↗
arXiv2017

Constraints on Mirror Models of Dark Matter from Observable Neutron-Mirror Neutron Oscillation

The process of neutron-mirror neutron oscillation, motivated by symmetric mirror dark matter models, is governed by two parameters: $n-n'$ mixing parameter $δ$ and $n-n'$ mass splitting $Δ$. For neutron mirror neutron oscillation to be observable, the splitting between their masses $Δ$ must be small and current experiments lead to $δ\leq 2\times 10^{-27}$ GeV and$Δ\leq 10^{-24}$ GeV. We show that in mirror universe models where this process is observable, this small mass splitting constrains the way that one must implement asymmetric inflation to satisfy the limits of Big Bang Nucleosynthesis on the number of effective light degrees of freedom. In particular we find that if asymmetric inflation is implemented by inflaton decay to color or electroweak charged particles, the oscillation is unobservable. Also if one uses SM singlet fields for this purpose, they must be weakly coupled to the SM fields.

hep-ph↗
arXiv2017

$Q Q \bar Q \bar Q$ states: masses, production, and decays

The question of whether there exist bound states of two heavy quarks $Q=(c,b)$ and antiquarks $\bar Q = (\bar c, \bar b)$, distinct from a pair of quark-antiquark mesons, has been debated for more than forty years. We suggest some means of producing and observing $Q_1 Q_2 \bar Q_3 \bar Q_4$ resonant states, concentrating on the $c c \bar c \bar c$ channel which is most easily produced and the $b b \bar b \bar b$ channel which has a better chance of being relatively narrow. We obtain $M_{(cc)(\bar c \bar c)} = 6,192 \pm 25$ MeV and $M_{(bb)(\bar b \bar b)} = 18,826 \pm 25$ MeV, for the charmed and bottom tetraquarks, respectively. Experimental search for these states in the relevant mass region is highly desirable.

hep-ph↗
arXiv2016

Semitauonic B Decay Anomaly

The anomalously large experimentally measured ratios of the semitauonic decay $B\rightarrow D^{(*)} +τ+ν$ and the corresponding semileptonic $B\rightarrow D^{*} +ł+\barν_l$ disagree with the predictions of the standard E.W + QCD model(S.M). We briefly comment on this disagreement and on possible new physics explanations which are rather constrained and difficult to implement.

hep-ph↗
arXiv2014

Supernova Bounds on the Dark Photon Using its Electromagnetic Decay

The hypothetical massive dark photon ($γ'$) which has kinetic mixing with the SM photon can decay electromagnetically to $e^+e^-$ pairs if its mass $m$ exceeds $2m_e$ and otherwise into three SM photons. These decays yield cosmological and supernovae associated signatures. We briefly discuss these signatures, particularly in connection with the supernova SN1987A and delineate the extra constraints that may then arise on the mass and mixing parameter of the dark photon. In particular, we find that for dark photon mass $m_{γ'}$ in the 5-20 MeV range, arguments based on supernova 1987A observations lead to a bound on $ε$ which is about 300 times stronger than the presently existing bounds based on energy loss arguments.

hep-ph↗
arXiv2014

Quirks and strings attached as the ultimate communication and acceleration devices

We point out that if a certain variant of "Quirks", particles that carry ordinary color and some other color' exist, then we can have a completely novel and efficient mode of long distance communications and of acceleration to very high energies. For very low scale $Λ'$ the scale of the new gauge group in the theory, and associated string tension of the new color' the Quirks can be captured in ordinary materials. Having then the Quirk Q' and anti-Quirk $\bar{Q}'$ in two separate piezoelectric crystals at arbitrarily far out points A and B allows Alice and Bob at these locations to communicate by generating transverse waves along the connecting color' string. Also releasing the Quirks allows them to collide at extremely high energies.

hep-ph↗
arXiv2014

Constraining the Higgs-Dilaton with LHC and Dark Matter Searches

We study a scenario in which the dilaton, a pseudo-Goldstone boson of the spontaneous breaking of conformal symmetry, provides a portal between dark matter and the visible sector. We consider the low-energy description of the theory in which the dilaton mixes with the Standard Model Higgs boson, thereby predicting a second scalar at or above the weak scale. We derive the collider and dark matter constraints on the corresponding parameter space and find that existing experimental data point towards the decoupling limit in which the CFT scale is well above the electroweak scale. Moreover, the thermal production of dark matter implies its mass is likely above the TeV scale. Upcoming direct detection experiments may allow for the discovery of the dilaton-mediated thermal dark matter while future collider studies will also be sensitive to the available parameter space.

hep-ph↗
arXiv2014

Collapses and Avoiding Wave Function Spreading

We address the impossibility of achieving exact time reversal in a system with many degrees of freedom. This is a particular example of the difficult task of "aiming" an initial classical state so as to become a specific final state. We also comment on the classical-to-quantum transition in any non-separable closed system of $n \geq 2$ degrees of freedom. Even if the system is initially in a well defined WKB, semi-classical state, quantum evolution and, in particular, multiple reflections at classical turning points make it completely quantum mechanical with each particle smeared almost uniformly over all the configuration space. The argument, which is presented in the context of $n$ hard discs, is quite general. Finally, we briefly address more complex quantum systems with many degrees of freedom and ask when can they provide an appropriate environment to the above simpler systems so that quantum spreading is avoided by continuously leaving "imprints" in the environment. We also discuss the possible connections with the pointer systems that are needed in the quantum-to-classical "collapse" transitions.

quant-ph↗
arXiv2014

Early inflation induced gravity waves can restrict Astro-Particle physics

In this paper, we discuss limits on various astro-particle scenarios if the scale \textit{and} the reheat temperature of the last relevant inflation were very high. While the observed "B" like pattern of polarizations of the CMB suggest a very high ($\ge 10^{16}\ GeV$) scale of a primordial (which motivated this work initially) and may reflect effects of dust, we believe that addressing these issues is nonetheless very useful. We recall the potential difficulties with various topological defects - monopoles, strings and domain walls generated at the SSB (spontaneous symmetry breaking) of various gauge symmetries. The main part of the paper is devoted to discussing difficulties with long-lived heavy particles, which could be dark matter but cannot efficiently annihilate to the required residual density because of basic S-Matrix unitarity/analyticity limits. We indicate in simple terms yet in some detail how the WIMP miracle occurs at $M(X)\sim{TeV}$ and how the axiomatic upper bound presently updated to $M(X) \le{110 TeV}$ was originally derived by Greist and Kamionokowski. We also argue that generically we expect the stronger $M(X)\le{20\ GeV}$ bound to hold. We then elaborate on the pure particle physics approaches aiming to enhance the annihilation and evade the bounds. We find that the only and in fact very satisfactory way of doing this requires endowing the particles with gauge interactions with a confinement scale lower than $M(X)$. We also comment on models with light $O(KeV)$ dark matter, which was supposed to be frozen in via out-of equilibrium processes so as to have the right relic densities pointing out that in many such cases \textit{very} low reheat temperatures are indeed required and speculate on the large desert scenario of particle physics. Most of what we discuss is not new but was not presented in a coherent fashion.

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