David M. Schmidt

Astrophysics with MILAGRO

This paper describes how data from a new type of air shower detector, MILAGRO, can shed light on a variety of interesting problems in astrophysics. MILAGRO has the capability to make observations of VHE/UHE emission from the recently discovered TeV gamma‐ray source Markarian 421, an Active Galactic Nucleus (AGN). An observation of the attenuation of this signal in the range of 1–20 TeV can be used to make the first measurement of the intergalactic infrared radiation. We will also describe how MILAGRO can improve the existing limits on the density of Primordial Black Holes (PBH) by three orders of magnitude. In addition, MILAGRO will have a large aperture and continuous operation which gives it the capability to search for VHE gamma ray bursts.

Study of the decays D r arrow K 3. pi

We report measurements of the decays {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup 0}, and {ital D}{sup 0}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup {minus}}{pi}{sup 0} from Fermilab photoproduction experiment E691. A complete resonant substructure analysis is used to determine the relative fractions and phases of amplitudes contributing to the decays {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, and {ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup 0}.

Measurement of the decaysD0→π−π+andD0→K−K+

Using data from Fermilab photoproduction experiment E691, we measure the ratio of branching fractions between the Cabibbo-suppressed modes {ital B}({ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+})/{ital B}({ital D}{sup 0}{r arrow}{pi}{sup {minus}}{pi}{sup +}) to be 1.95{plus minus}0.34{plus minus}0.22. We also report branching fractions for the modes {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} and {ital D}{sup 0}{r arrow}{pi}{sup {minus}}{pi}{sup +} relative to the Cabibbo-allowed decay {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}. Furthermore, we place an upper limit of 0.45 at the 90% C.L. on the {ital CP}-violating asymmetry in {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} vs {ital {bar D}} {sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} decays.

Measurement of the decays D sup 0 r arrow. pi. sup minus. pi. sup + and D sup 0 r arrow K sup minus K+

Using data from Fermilab photoproduction experiment E691, we measure the ratio of branching fractions between the Cabibbo-suppressed modes {ital B}({ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+})/{ital B}({ital D}{sup 0}{r arrow}{pi}{sup {minus}}{pi}{sup +}) to be 1.95{plus minus}0.34{plus minus}0.22. We also report branching fractions for the modes {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} and {ital D}{sup 0}{r arrow}{pi}{sup {minus}}{pi}{sup +} relative to the Cabibbo-allowed decay {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}. Furthermore, we place an upper limit of 0.45 at the 90% C.L. on the {ital CP}-violating asymmetry in {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} vs {ital {bar D}} {sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} decays.

Measurement of the decays D0--> pi - pi + and D0-->K-K+

Using data from Fermilab photoproduction experiment E691, we measure the ratio of branching fractions between the Cabibbo-suppressed modes {ital B}({ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+})/{ital B}({ital D}{sup 0}{r arrow}{pi}{sup {minus}}{pi}{sup +}) to be 1.95{plus minus}0.34{plus minus}0.22. We also report branching fractions for the modes {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} and {ital D}{sup 0}{r arrow}{pi}{sup {minus}}{pi}{sup +} relative to the Cabibbo-allowed decay {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}. Furthermore, we place an upper limit of 0.45 at the 90% C.L. on the {ital CP}-violating asymmetry in {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} vs {ital {bar D}} {sup 0}{r arrow}{ital K}{sup {minus}}{ital K+} decays.

Measurement of the form factors in the decay D+-->K-bar*0e+ nu e.

We have measured the three form factors governing the decay {ital D}{sup +}{r arrow}{ital {bar K}} {sup *0}{ital e}{sup +}{nu}{sub {ital e}}, observed in Fermilab photoproduction experiment E691, using the complete decay distribution of the data. The results are {ital A}{sub 1}(0)=0.46{plus minus}0.05{plus minus}0.05, {ital A}{sub 2}(0)=0.0{plus minus}0.2{plus minus}0.1, and {ital V}(0)=0.9{plus minus}0.3{plus minus}0.1 for the two axial-vector and the vector form factors, respectively. The {ital {bar K}} {sup *0} mesons have a ratio of longitudinal to transverse polarization of 1.8{sub {minus}0.4}{sup +0.6}{plus minus}0.3. These results are significantly different from values predicted by a number of different models.

Measurement of the form factors in the decay D sup + r arrow K sup *0 e sup +. nu. sub e

We have measured the three form factors governing the decay {ital D}{sup +}{r arrow}{ital {bar K}} {sup *0}{ital e}{sup +}{nu}{sub {ital e}}, observed in Fermilab photoproduction experiment E691, using the complete decay distribution of the data. The results are {ital A}{sub 1}(0)=0.46{plus minus}0.05{plus minus}0.05, {ital A}{sub 2}(0)=0.0{plus minus}0.2{plus minus}0.1, and {ital V}(0)=0.9{plus minus}0.3{plus minus}0.1 for the two axial-vector and the vector form factors, respectively. The {ital {bar K}} {sup *0} mesons have a ratio of longitudinal to transverse polarization of 1.8{sub {minus}0.4}{sup +0.6}{plus minus}0.3. These results are significantly different from values predicted by a number of different models.

Measurement of the form factors in the decayD+→K¯*0e+νe

We have measured the three form factors governing the decay {ital D}{sup +}{r arrow}{ital {bar K}} {sup *0}{ital e}{sup +}{nu}{sub {ital e}}, observed in Fermilab photoproduction experiment E691, using the complete decay distribution of the data. The results are {ital A}{sub 1}(0)=0.46{plus minus}0.05{plus minus}0.05, {ital A}{sub 2}(0)=0.0{plus minus}0.2{plus minus}0.1, and {ital V}(0)=0.9{plus minus}0.3{plus minus}0.1 for the two axial-vector and the vector form factors, respectively. The {ital {bar K}} {sup *0} mesons have a ratio of longitudinal to transverse polarization of 1.8{sub {minus}0.4}{sup +0.6}{plus minus}0.3. These results are significantly different from values predicted by a number of different models.