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L. Clavelli

Publications and source records attributed to L. Clavelli.

At least 37 records · Page 2Linked to original sources
arXiv2006

Neighboring Valley in the String Landscape

The observation in the universe of a small but positive vacuum energy strongly suggests, in the string landscape picture, that there will ultimately be a phase transition to an exactly supersymmetric universe. This ground state or "true vacuum" of the universe could be similar to the minimal supersymmetric standard model with all the susy breaking parameters set to zero. Alternatively, it might be similar to the prominent superstring theories with nine flat space dimensions or to the supersymmetric anti-deSitter model that seems to be equivalent to a conformal field theory. We propose that the dominant phenomenological feature of these potential future universes is the weakening of the Pauli principle due to Fermi-Bose degeneracy. Providing the phase transition occurs in the cosmologically near future, an exact supersymmetry could extend the life expectancy of intelligent civilizations far beyond what would be possible in the broken susy universe.

hep-ph↗
arXiv2006

Gravitational collapse of a susy star

The evidence for a positive vacuum energy in our universe suggests that we might be living in a false vacuum destined to ultimately decay to a true vacuum free of dark energy. At present the simplest example of such a universe is one that is exactly supersymmetric (susy). It is expected that the nucleation rate of critically sized susy bubbles will be enhanced in regions of high density such as in degenerate stars. The consequent release of energy stored in Pauli towers provides a possible model for gamma ray bursts. Whether or not all or any of the currently observed bursts are due to this mechanism, it is important to define the signatures of this susy phase transition. After such a burst, due to the lifting of degeneracy pressure, the star would be expected to collapse into a black hole even though its mass is below the Chandrasekhar limit. Previous studies have treated the star as fully releasing its stored energy before the collapse. In this article we make an initial investigation of the effects of the collapse during the gamma ray emission.

hep-ph↗
arXiv2005

Properties of a future susy universe

In the string landscape picture, the effective potential is characterized by an enormous number of local minima of which only a minuscule fraction are suitable for the evolution of life. In this "multiverse", random transitions are continually made between the various minima with the most likely transitions being to minima of lower vacuum energy. The inflationary era in the very early universe ended with such a transition to our current phase which is described by a broken supersymmetry and a small, positive vacuum energy. However, it is likely that an exactly supersymmetric (susy) phase of zero vacuum energy as in the original superstring theory also exists and that, at some time in the future, there will be a transition to this susy world. In this article we make some preliminary estimates of the consequences of such a transition.

hep-th↗
arXiv2005

A supersymmetric model of gamma ray bursts

We propose a model for gamma ray bursts in which a star subject to a high level of fermion degeneracy undergoes a phase transition to a supersymmetric state. The burst is initiated by the transition of fermion pairs to sfermion pairs which, uninhibited by the Pauli exclusion principle, can drop to the ground state of minimum momentum through photon emission. The jet structure is attributed to the Bose statistics of sfermions whereby subsequent sfermion pairs are preferentially emitted into the same state (sfermion amplification by stimulated emission). Bremsstrahlung gamma rays tend to preserve the directional information of the sfermion momenta and are themselves enhanced by stimulated emission.

hep-ph↗
arXiv2005

Growth of a susy bubble: inhomogeneity effects

In a dense star, the Pauli exclusion principle functions as an enormous energy storage mechanism. Supersymmetry could provide a way to recapture this energy. If there is a transition to an exactly supersymmetric (susy) phase, the trapped energy can be released with consequences similar to gamma ray burst observations. Previous zeroth order calculations have been based on the behavior in a prototypical white dwarf of solar mass and earth radius (such as Sirius B) and have neglected density inhomogeneity. In this article we show that the effects of density inhomogeneity and of variations in masses and radii are substantial enough to encourage further exploration of the susy star model. In addition, the effects discussed here have possible applications to the growth of bubbles in other phase transition models in dense matter.

hep-ph↗
arXiv2005

Electron to selectron pair conversion in a SUSY bubble

In the standard model, energy release in dense stars is severely restricted by the Pauli exclusion principle. However, if, in regions of space of high fermion degeneracy, there is a phase transition to a state of exact supersymmetry (SUSY), fermion to sfermion pair conversion followed by radiative transitions to the Bose ground state could lead to a highly collimated gamma ray burst. We calculate the cross section for electron to selectron pair conversion in a SUSY bubble and construct a monte carlo for the resulting sfermion amplification by stimulated emission.

hep-ph↗
arXiv2005

A Susy Phase Transition as Central Engine

For several decades the energy source powering supernovae and gamma ray bursts has been a troubling mystery. Many articles on these phenomena have been content to model the consequences of an unknown "central engine" depositing a large amount of energy in a small region. In the case of supernovae this is somewhat unsettling since the type 1a supernovae are assumed to be "standardizable candles" from which important information concerning the dark energy can be derived. It should be expected that a more detailed understanding of supernovae dynamics could lead to a reduction of the errors in this relationship. Similarly, the current state of the standard model theory of gamma ray bursts, which in some cases have been associated with supernovae, has conceptual gaps not only in the central engine but also in the mechanism for jet collimation and the lack of baryon loading. We discuss here the Supersymmetric (susy) phase transition model for the central engine.

hep-ph↗
arXiv2004

R Parity Violating Decays of the Gluino

Assuming the lightest supersymmetric particle is the gluino, we treat the decays gluino->quark-antiquark-neutrino and gluino->gluon-neutrino. Such couplings can be induced by the R parity violating quark-squark-lepton interaction which can also be responsible for neutrino masses and mixings. These R parity violating gluino decays have the same final state structure (jets plus missing energy) as previously considered decays into quark-antiquark-photino and gluon-gravitino but with significantly different gluino lifetimes.

hep-ph↗
arXiv2004

A supersymmetric origin of gamma ray bursts

Bright bursts of gamma rays from outer space have been puzzling Astronomers for more than thirty years and there is still no conceptually complete model for the phenomenon within the standard model of particle physics. Is it time to consider a supersymmetric (SUSY) origin for these bursts to add to the astronomical indications of supersymmetry from dark matter?

hep-ph↗
arXiv2002

Beyond the Zero-Binding Approximation in Quarkonium

The hadronic decays of quarkonium and the B meson inclusive decay into J/Psi + X, if treated in the zero-binding approximation, suggest a value of the strong coupling constant much smaller than the value implied in the standard model by running from measurements at the Z. Thus, assuming the standard model is correct in the low energy region, there must be very substantial relativistic binding corrections to these processes. We discuss the wave function factor appearing in covariant treatments of quarkonium production and decay processes with special attention to the way in which the spin of the quarks carries over into the spin of the bound state. We find that Lorentz covariance requires that the bound state be a superposition of free quark and antiquark spinors notably different from the usual ones. We resolve a superficial apparent paradox suggesting that the relative momentum of the quarks should lie in a plane perpendicular to the spin quantization axis and we calculate the J/Psi binding corrections to lepton pair decay and to the inclusive B decay.

hep-ph↗
arXiv2001

Parity and Time Reversal in J/Psi Decay

With the prospect of large numbers of $J/Ψ$ decay events becoming available in the near future, it is interesting to search for symmetry violating effects as probes of new physics and tests of the standard model. $J/Ψ$ decay events could provide the first observation of weak effects in otherwise strongly decaying particles. We calculate a T odd asymmetry in the $J/Ψ$ decay into photon plus lepton pair due to Z boson exchange. Extensions to hadronic final states are also discussed.

hep-ph↗
arXiv2001

Upsilon Decay to a Pair of Bottom Squarks

We calculate the rate for $Υ$ decay into a pair of bottom squarks as a function of the masses of the bottom squark and the gluino. Data from decays of the $Υ$ states could provide significant new bounds on the existence and masses of these supersymmetric particles.

hep-ph↗
arXiv2000

New Possibilities for a Light Gluino

Despite many positive indirect indications of light gluinos direct searches for the expected signatures of gluino containing hadrons have so far turned up negative severely restricting the allowable windows in gluino mass. After briefly reviewing the status, we discuss a possible new decay scenario that could have allowed light gluinos to evade direct detection with possible consequences for other measurements.

hep-ph↗
arXiv2000

Gaugino Mass Dependence of Electron and Neutron Electric Dipole Moments

Unless squarks and sleptons are in the multi-TeV region or above, CP violating induced electric dipole moments of elementary particles can pose significant puzzles for supersymmetric (SUSY) models. We study the dipole-moment-inducing one-loop amplitudes as a function of the fundamental SUSY parameters and show that these puzzles are removed if there is a sufficiently large hierarchy between the gaugino masses and the scalar mass. We comment on the experimental status of the low gaugino mass scenario.

hep-ph↗
arXiv2000

Report of the Beyond the MSSM Subgroup for the Tevatron Run II SUSY/Higgs Workshop

There are many low-energy models of supersymmetry breaking parameters which are motivated by theoretical and experimental considerations. Here, we discuss some of the lesser-known theories of low-energy supersymmetry, and outline their phenomenological consequences. In some cases, these theories have more gauge symmetry or particle content than the Minimal Supersymmetric Standard Model. In other cases, the parameters of the Lagrangian are unusual compared to commonly accepted norms (e.g., Wino LSP, heavy gluino LSP, light gluino, etc.). The phenomenology of supersymmetry varies greatly between the different models. Correspondingly, particular aspects of the detectors assume greater or lesser importance. Detection of supersymmetry and the determination of all parameters may well depend upon having the widest possible view of supersymmetry phenomenology.

hep-ph↗
arXiv1998

Light Gluino Predictions for Jet Cross Sections in Tevatron Run II

The CDF inclusive jet transverse energy cross section at 1.8 TeV suggests anomalous behavior at both low and high transverse energies. In addition the scaled ratio of the 0.63 TeV to 1.8 TeV data lies significantly below the standard model prediction and suggests structure not attributable to standard model processes. These anomalies are in line with what would be expected in the light gluino scenario. We perform a unified fit and extrapolate to two TeV to predict the results at run II.

hep-ph↗
arXiv1998

Neutrino Masses in R Parity Violating Supersymmetry

We discuss a model for neutrino masses and mixings based on R parity violating Yukawa couplings. The model requires no right-handed neutrinos. It accommodates the SuperKamiokande data on atmospheric neutrinos and successfully relates this data to the mass difference for solar neutrinos in the small-angle MSW solution. We obtain an unexpected testable pattern for the three neutrino flavors.

hep-ph↗