arXiv subjects

F. Halzen

Publications and source records attributed to F. Halzen.

At least 91 records · Page 5Linked to original sources

arXiv2001

The prompt TeV-PeV atmospheric neutrino window

We discuss the possible existence of an observational window, in the TeV-PeV energy range, for the detection of prompt neutrinos from the decay of charmed particles produced in cosmic ray interactions with the atmosphere. We calculate the event rates for muon and tau neutrinos of heavy quark, mostly charm, origin. We argue that their prompt fluxes are observable in a kilometer-scale neutrino telescope, even though the calculations are subjected to large uncertainties, which we quantify. We raise the possibility that a small component of prompt neutrinos may already be present in the observed samples of current experiments. We also discuss the interplay of the predicted fluxes with those produced by the flavor oscillation of conventional atmospheric neutrinos, and by anticipated cosmic sources.

hep-ph↗

arXiv2001

High Energy Neutrino Astronomy: Towards Kilometer-Scale Detectors

Of all high-energy particles, only neutrinos can directly convey astronomical information from the edge of the universe---and from deep inside the most cataclysmic high-energy processes. Copiously produced in high-energy collisions, travelling at the velocity of light, and not deflected by magnetic fields, neutrinos meet the basic requirements for astronomy. Their unique advantage arises from a fundamental property: they are affected only by the weakest of nature's forces (but for gravity) and are therefore essentially unabsorbed as they travel cosmological distances between their origin and us. Many of the outstanding mysteries of astrophysics may be hidden from our sight at all wavelengths of the electromagnetic spectrum because of absorption by matter and radiation between us and the source. For example, the hot dense regions that form the central engines of stars and galaxies are opaque to photons. In other cases, such as supernova remnants, gamma ray bursters, and active galaxies, all of which may involve compact objects or black holes at their cores, the precise origin of the high-energy photons emerging from their surface regions is uncertain. Therefore, data obtained through a variety of observational windows---and especially through direct observations with neutrinos---may be of cardinal importance. In this talk, the scientific goals of high energy neutrino astronomy and the technical aspects of water and ice Cherenkov detectors are examined, and future experimental possibilities, including a kilometer-square deep ice neutrino telescope, are explored.

astro-ph↗

arXiv2001

10^20 eV Cosmic Ray and Particle Physics with IceCube

We show that a kilometer-scale neutrino observatory, though optimized for detecting neutrinos of TeV to PeV energy, can reveal the science associated with the enigmatic super-EeV radiation in the Universe. Speculations regarding its origin include heavy relics from the early Universe, particle interactions associated with the Greisen cutoff, and topological defects which are remnant cosmic structures associated with phase transitions in grand unified gauge theories. We show that it is a misconception that new instruments optimized to EeV energy can exclusively do this important science. Because kilometer-scale neutrino telescopes such as IceCube can reject the atmospheric neutrino background by identifying the very high energy of the signal events, they have sensitivity over the full solid angle, including the horizon where most of the signal is concentrated. This is critical because upgoing neutrino-induced muons, considered in previous calculations, are absorbed by the Earth. Previous calculations have underestimated the event rates of IceCube for EeV signals by over one order of magnitude.

astro-ph↗

arXiv2001

Survival Probability of Large Rapidity Gaps in pbar p, pp, gamma p and gamma gamma Collisions

Using an eikonal analysis, we simultaneously fit a QCD-inspired parameterization of all accelerator data on forward proton-proton and antiproton-proton scattering amplitudes, together with cosmic ray data (using Glauber theory), to predict proton-air and proton-proton cross sections at energies near \sqrt s \approx 30 TeV. The p-air cosmic ray measurements greatly reduce the errors in the high energy proton-proton and proton-air cross section predictions--in turn, greatly reducing the errors in the fit parameters. From this analysis, we can then compute the survival probability of rapidity gaps in high energy pbar p and pp collisions, with high accuracy in a quasi model-free environment. Using an additive quark model and vector meson dominance, we note that that the survival probabilities are identical, at the same energy, for gamma p and gamma gamma collisions, as well as for nucleon-nucleon collisions. Significantly, our analysis finds large values for gap survival probabilities, \approx 30% at \sqrt s = 200 GeV, \approx 21% at \sqrt s = 1.8 TeV and \approx %%13% at \sqrt s = 14 TeV.

hep-ph↗

arXiv2000

10^20 eV Cosmic-Ray and Particle Physics with Kilometer-Scale Neutrino Telelscopes

We show that a kilometer-scale neutrino observatory, though optimized for TeV to PeV energy, is sensitive to the neutrinos associated with super-EeV sources. These include super-heavy relics, neutrinos associated with the Greisen cutoff, and topological defects which are remnant cosmic structures associated with phase transitions in grand unified gauge theories. It is a misconception that new instruments optimized to EeV energy are required to do this important science. Because kilometer-scale neutrino telescopes can reject atmospheric backgrounds by establishing the very high energy of the signal events, they have sensitivity over the full solid angle, including the horizon where most of the signal is concentrated. This is important because up-going neutrino-induced muons, routinely considered in previous calculations, are absorbed by the Earth.

astro-ph↗

arXiv2000

High Energy Neutrinos from Gamma Ray Bursts: Event Rates in Neutrino Telescopes

Following Waxman and Bahcall we calculate the event rate, energy and zenith angle dependence of neutrinos produced in the fireball model of gamma ray bursts (GRB). We emphasize the primary importance of i) burst-to-burst fluctuations and ii) absorption of the neutrinos in the Earth. From the astronomical point of view, we draw attention to the sensitivity of neutrino measurements to the boost Lorentz factor of the fireball $Γ$, which is central to the fireball model, and only indirectly determined by follow-up observations. Fluctuations result in single bursts emitting multiple neutrinos, making it possible to determine the flavor composition of a beam observed after a baseline of thousands of Megaparsecs.

astro-ph↗

arXiv2000

Extending the Frontiers - Reconciling Accelerator and Cosmic Ray p-p Cross Sections

We simultaneously fit a QCD-inspired parameterization of all accelerator data on forward proton-proton and antiproton-proton scattering amplitudes, together with cosmic ray data (using Glauber theory), to predict proton-air and proton-proton cross sections at energies near \sqrt s \approx 30 TeV. The p-air cosmic ray measurements provide a strong constraint on the inclusive particle production cross section, as well as greatly reducing the errors on the fit parameters---in turn, greatly reducing the errors in the high energy proton-proton and proton-air cross section predictions.

hep-ph↗

arXiv2000

Breaking the Barriers - Uniting Accelerator and Cosmic Ray p-p Cross Sections

We make a QCD-inspired parameterization of all accelerator data on forward proton-proton and antiproton-proton scattering amplitudes. Using vector dominance and the additive quark model, we show that the same parameters also fit gamma p and gamma gamma interactions. Using the high energy predictions of our model, along with Glauber theory, we calculate proton-air cross sections at energies near sqrt s approx 30 TeV. The comparisons of p-air cosmic ray measurements with our QCD model predictions provide a strong constraint on the inclusive particle production cross section.

hep-ph↗

arXiv1999

Neutrino Event Rates from Gamma Ray Bursts

We recalculate the diffuse flux of high energy neutrinos produced by Gamma Ray Bursts (GRB) in the relativistic fireball model. Although we confirm that the average single burst produces only ~10^{-2} high energy neutrino events in a detector with 1 km^2 effective area, i.e. about 10 events per year, we show that the observed rate is dominated by burst-to-burst fluctuations which are very large. We find event rates that are expected to be larger by one order of magnitude, likely more, which are dominated by a few very bright bursts. This greatly simplifies their detection.

astro-ph↗

arXiv1999

Predicting Proton-Air Cross Sections at sqrt s ~30 TeV, using Accelerator and Cosmic Ray Data

We use the high energy predictions of a QCD-inspired parameterization of all accelerator data on forward proton-proton and antiproton-proton scattering amplitudes, along with Glauber theory, to predict proton-air cross sections at energies near \sqrt s \approx 30 TeV. The parameterization of the proton-proton cross section incorporates analyticity and unitarity, and demands that the asymptotic proton is a black disk of soft partons. By comparing with the p-air cosmic ray measurements, our analysis results in a constraint on the inclusive particle production cross section.

hep-ph↗

arXiv1999

Color Evaporation Induced Rapidity Gaps

We show that soft color rearrangement of final states can account for the appearance of rapidity gaps between jets. In the color evaporation model the probability to form a gap is simply determined by the color multiplicity of the final state. This model has no free parameters and reproduces all data obtained by the ZEUS, H1, D0, and CDF collaborations.

hep-ph↗

arXiv1999

High Energy Neutrino Astronomy: WIN 99

Although high energy neutrino astronomy is a multidisciplinary science, gamma ray bursts have become the theoretical focus since recent astronomical observations revealed their potential as cosmic particle accelerators. This spotlight is shared with investigations of the potential of high energy telescopes to observe oscillating atmospheric neutrinos. The Superkamiokande results have boosted atmospheric neutrinos from a calibration tool and a background for doing astronomy, to an opportunity to confirm the evidence for neutrino mass. Nevertheless, the highlights are mostly on the experimental front with the completion of the first-generation Baikal and AMANDA detectors. Neutrino signals from the Lake Baikal detector bode well for the flurry of activities in the Mediterranean. The completed AMANDA telescope announced first light, neutrinos actually, at this meeting.

astro-ph↗

arXiv1999

New Worlds in Astroparticle Physics: Summary Talk

Surrounded by stunning Algarve landscapes not far from where Henry the Navigator organized the voyages that mapped the Earth, particle astrophysicists discussed new initiatives to explore the cosmos. While first generation experiments opened new voyages of the mind with evidence for neutrino mass and a cosmological constant, much of the discussion focussed on novel experimental assaults on the secrets of the Universe. While "big-time" particle physics entered space with AMS and high energy neutrino telescopes saw first light, neutrinos actually, at Lake Baikal and South Pole, it is the hope that new and even more ambitious experimental initiatives, ranging from gravitational wave detectors to the MAP and Planck microwave satellite-borne detectors, will boost particle astrophysics into "the" physics and astronomy of the next millennium.

astro-ph↗

arXiv1999

Muon Detection of TeV Gamma Rays from Gamma Ray Bursts

Because of the limited size of the satellite-borne instruments, it has not been possible to observe the flux of gamma ray bursts (GRB) beyond GeV energy. We here show that it is possible to detect the GRB radiation of TeV energy and above, by detecting the muon secondaries produced when the gamma rays shower in the Earth's atmosphere. Observation is made possible by the recent commissioning of underground detectors (AMANDA, the Lake Baikal detector and MILAGRO) which combine a low muon threshold of a few hundred GeV or less, with a large effective area of 10^3 m^2 or more. Observations will not only provide new insights in the origin and characteristics of GRB, they also provide quantitative information on the diffuse infrared background.

astro-ph↗

arXiv1999

On Forward J/ψProduction at Fermilab Tevatron

The D0 Collaboration has recently reported the measurement of J/ψproduction at low angle. We show here that the inclusion of color octet contributions in any framework is able to reproduce this data.

hep-ph↗

arXiv1998

Lectures on Neutrino Astronomy: Theory and Experiment

1. Overview of neutrino astronomy: multidisciplinary science. 2. Cosmic accelerators: the highest energy cosmic rays. 3. Neutrino beam dumps: supermassive black holes and gamma ray bursts. 4. Neutrino telescopes: water and ice. 5. Indirect dark matter detection. 6. Towards kilometer-scale detectors.

astro-ph↗

arXiv1998

The AMANDA Neutrino Telescope

With an effective telescope area of order $10^4$ m$^2$ for TeV neutrinos, a threshold near $\sim$50 GeV and a pointing accuracy of 2.5 degrees per muon track, the AMANDA detector represents the first of a new generation of high energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We describe early results on the calibration of natural deep ice as a particle detector as well as on AMANDA's performance as a neutrino telescope.

hep-ex↗

arXiv1998

Photon-Proton and Photon-Photon Scattering from Nucleon-Nucleon Forward Amplitudes

We show that the data on $γp$ and $γγ$ interactions can be derived from the $pp$ and $\bar p p$ forward scattering amplitudes using vector meson dominance and the additive quark model. The nucleon-nucleon data are parameterized using a model where high energy cross sections rise with energy as a consequence of the increasing numbers of soft partons populating the colliding particles. We present detailed descriptions of the data on the total and elastic cross sections, the ratio of the real to imaginary part of the forward scattering amplitude, and on the slope of the differential cross sections for $pp$, $\bar p p$, $γp$, $γγ$, $γp \to γV$ and $γγ\to V_i V_j$ reactions, where $V= ρ, ω, ϕ$. We make a wide range of predictions for future HERA and LHC experiments and for $γγ$ measurements at LEP.

hep-ph↗