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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Direct Photons As Probes Of Low Mass Strings At The Lhc, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Tomasz Taylor
Direct Photons As Probes Of Low Mass Strings At The Lhc, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Tomasz Taylor
Haim Goldberg
The LHC program will include the identification of events with single prompt high-k_\perp photons as probes of new physics. We show that this channel is uniquely suited to search for experimental evidence of TeV-scale open string theory. At the parton level, we analyze single photon production in gluon fusion, gg \to \gamma g, with open string states propagating in intermediate channels. If the photon mixes with the gauge boson of the baryon number, which is a common feature of D-brane quivers, the amplitude appears already at the string disk level. It is completely determined by the mixing parameter (which is …
Clustering In Highest Energy Cosmic Rays: Physics Or Statistics?, Haim Goldberg, Thomas J. Weiler
Clustering In Highest Energy Cosmic Rays: Physics Or Statistics?, Haim Goldberg, Thomas J. Weiler
Haim Goldberg
Directional clustering can be expected in cosmic ray observations due to purely statistical fluctuations for sources distributed randomly in the sky. We develop an analytic approach to estimate the probability of random cluster configurations, and use these results to study the strong potential of the HiRes, Auger, Telescope Array and EUSO/OWL/AirWatch facilities for deciding whether any observed clustering is most likely due to non-random sources.
Dijet Signals For Low Mass Strings At The Lhc, Luis A. Anchordoqui, Haim Goldberg, Dieter Lüst, Satoshi Nawata, Stephan Stieberger, Tomasz T. Taylor
Dijet Signals For Low Mass Strings At The Lhc, Luis A. Anchordoqui, Haim Goldberg, Dieter Lüst, Satoshi Nawata, Stephan Stieberger, Tomasz T. Taylor
Haim Goldberg
We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we discuss possible signals of string physics at the Large Hadron Collider (LHC). In such D-brane constructions, the dominant contributions to full-fledged string amplitudes for all the common QCD parton subprocesses leading to dijets are completely independent of the details of compactification, and can be evaluated in …
Black Hole Chromosphere At The Cern Lhc, Luis Anchordoqui, Haim Goldberg
Black Hole Chromosphere At The Cern Lhc, Luis Anchordoqui, Haim Goldberg
Haim Goldberg
If the scale of quantum gravity is near a TeV, black holes will be copiously produced at the LHC. In this work we study the main properties of the light descendants of these black holes. We show that the emitted partons are closely spaced outside the horizon, and hence they do not fragment into hadrons in vacuum but more likely into a kind of quark-gluon plasma. Consequently, the thermal emission occurs far from the horizon, at a temperature characteristic of the QCD scale. We analyze the energy spectrum of the particles emerging from the "chromosphere", and find that the hard …
Constraints On Unparticle Physics From Solar And Kamland Neutrinos, Luis Anchordoqui, Haim Goldberg
Constraints On Unparticle Physics From Solar And Kamland Neutrinos, Luis Anchordoqui, Haim Goldberg
Haim Goldberg
Interest has been directed recently towards low energy implications of a non-trivial conformal sector of an effective field theory with an IR fixed point (ΛU), manifest in terms of "unparticles" with bizarre properties. We re-examine the implications of the limits on decay lifetimes of solar neutrinos for unparticle interactions. We study in detail the fundamental parameter space (ΛU,M) and derive bounds on the energy scale M characterizing the new physics. We work strictly within the framework where conformal invariance holds down to low energies. We first assume that couplings of the unparticle sector to the Higgs field are suppressed and …
Can Hidden Gauginos Form Condensates?, Haim Goldberg
Can Hidden Gauginos Form Condensates?, Haim Goldberg
Haim Goldberg
Supersymmetry breaking may be linked to the formation of gaugino condensates in a hidden sector. In this work, the process of formation of the condensate is examined in a cosmological context, using an effective field theory of the gaugino bilinear which provides a reasonable interpolation between the high- and low-temperature phases. The implementation of anomaly requirements generates a large potential barrier between the zero-condensate configuration and that of the true (SUSY-breaking) vacuum. As a consequence, the transition to bubbles of true vacuum may be subject to an enormous exponential suppression. This leads to the same difficulties with inhomogeneity of the …
Auger Test Of The Cen A Model Of Highest Energy Cosmic Rays, Luis A. Anchordoqui, Haim Goldberg, Thomas J. Weiler
Auger Test Of The Cen A Model Of Highest Energy Cosmic Rays, Luis A. Anchordoqui, Haim Goldberg, Thomas J. Weiler
Haim Goldberg
If, as recently proposed by Farrar and Piran, Cen A is the source of cosmic rays detected above the Greisen-Zatsepin-Kuz’min cutoff, neutrons are ≈ 140 more probable than protons to be observed along its line of sight. This is because the proton flux is rendered nearly isotropic by O(μG) intergalactic magnetic fields. With the anticipated aperture of the Southern Auger Observatory, one may expect on the order of 2 neutron events/year above 1020 eV in the line of sight of Cen A.
Cosmology From String Theory, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Carlos Nuñez
Cosmology From String Theory, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Carlos Nuñez
Haim Goldberg
We explore the cosmological content of Salam-Sezgin six dimensional supergravity, and find a solution to the field equations in qualitative agreement with observation of distant supernovae, primordial nucleosynthesis abundances, and recent measurements of the cosmic microwave background. The carrier of the acceleration in the present de Sitter epoch is a quintessence field slowly rolling down its exponential potential. Intrinsic to this model is a second modulus which is automatically stabilized and acts as a source of cold dark matter, with a mass proportional to an exponential function of the quintessence field (hence realizing VAMP models within a String context). However, …
Decay Widths Of Lowest Massive Regge Excitations Of Open Strings, Luis A. Anchordoqui, Haim Goldberg, Tomasz R. Taylor
Decay Widths Of Lowest Massive Regge Excitations Of Open Strings, Luis A. Anchordoqui, Haim Goldberg, Tomasz R. Taylor
Haim Goldberg
With the advent of the LHC there is widespread interest in the discovery potential for physics beyond the standard model. In TeV-scale open string theory, the new physics can be manifest in the excitation and decay of new resonant structures, corresponding to Regge recurrences of standard model particles. An essential input for the prediction of invariant mass spectra of the decay products (which could serve to identify the resonance as a string excitation) are the partial and total widths of the decay products. We present a parameter-free calculation of these widths for the first Regge recurrence of the SU(3) gluon …
Anisotropy At The End Of The Cosmic Ray Spectrum?, Luis A. Anchordoqui, Haim Goldberg, Diego F. Torres
Anisotropy At The End Of The Cosmic Ray Spectrum?, Luis A. Anchordoqui, Haim Goldberg, Diego F. Torres
Haim Goldberg
The starburst galaxies M82 and NGC253 have been proposed as the primary sources of cosmic rays with energies above 1020.3 eV. For energies ≳ 1020.3 eV the model predicts strong anisotropies. We calculate the probabilities that the latter can be due to chance occurrence. For the highest energy cosmic ray events in this energy region, we find that the observed directionality has less than 1% probability of occurring due to random fluctuations. Moreover, during the first 5 years of operation at Auger, the observation of even half the predicted anisotropy has a probability of less than 10−5 to occur by …
Black Holes From Cosmic Rays: Probes Of Extra Dimensions And New Limits On Tev-Scale Gravity, Luis Anchordoqui, Jonathan Feng, Haim Goldberg, Alfred Shapere
Black Holes From Cosmic Rays: Probes Of Extra Dimensions And New Limits On Tev-Scale Gravity, Luis Anchordoqui, Jonathan Feng, Haim Goldberg, Alfred Shapere
Haim Goldberg
If extra spacetime dimensions and low-scale gravity exist, black holes will be produced in observable collisions of elementary particles. For the next several years, ultra-high energy cosmic rays provide the most promising window on this phenomenon. In particular, cosmic neutrinos can produce black holes deep in the Earth’s atmosphere, leading to quasi-horizontal giant air showers. We determine the sensitivity of cosmic ray detectors to black hole production and compare the results to other probes of extra dimensions. With n ≥ 4 extra dimensions, current bounds on deeply penetrating showers from AGASA already provide the most stringent bound on low-scale gravity, …