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At least 361 records · Page 20

Debris/ice/TPS assessment and integrated photographic analysis for Shuttle Mission STS-62

A pre-launch debris inspection of the pad and Shuttle vehicle was conducted on 2 March 1994. The detailed walkdown of Launch Pad 39B and MLP-1 also included the primary flight elements OV-102 Columbia (16th flight), ET-62 (LWT 55), and BI-064 SRB's. There were no significant facility or vehicle anomalies. After the launch on March 4th, a debris inspection of Pad 39B was performed. Damage to the pad overall was minimal. On-orbit photographs taken by the flight crew and two films from the ET/ORB umbilical cameras of the External Tank after separation from the Orbiter revealed no major damage or lost flight hardware that would have been a safety of flight concern. Orbiter performance on final approach appeared normal. Infrared imagery of landing gear deployment showed the loss of thermal barrier from the nose gear wheel well. The missing thermal barrier material was not recovered. The Solid Rocket Boosters were inspected at Hanger AF after retrieval. Both frustums had a combined total of 44 MSA-2 debonds over fasteners. Significant amounts of BTA had been applied to closeouts on the RH frustum, forward skirt, and aft skirt. Hypalon paint was blistered/missing over the areas were the BTA had been applied. The underlying BTA was not sooted (IFA STS-62-B-1). Investigation of this condition has concluded there was insufficient heat rates to cause blistering of the Hypalon until late in the ascent phase. A post landing inspection of OV-102 was conducted after the landing at KSC. The Orbiter TPS sustained a total of 97 hits, of which 16 had a major dimension of 1 inch or larger. The Orbiter lower surface had a total of 36 hits, of which 7 had a major dimension of 1 inch or larger. Based on these numbers and comparison to statistics from previous missions of similar configuration, both the total number of debris hits and the number of hits 1 inch or larger was less than average. Six thermal barriers, total size approximately 36 in. x 3 in. x 1.5 in., and one corner tile piece 4 in. x 4 in., were missing from the nose landing gear doors. Runway infrared cameras recorded these objects falling from the Orbiter when the nose landing gear doors were opened on final approach. A search of the area under the flight path failed to recover the missing thermal batteries, which may be submerged in the large body of water south of the runway. The cause for the loss of the material was attributed to the way the substrate was prepared for bonding at the vendor. Orbiter post landing microchemical sample results revealed a variety of residuals in the Orbiter window samples. These were attributed to SRB BSM exhaust, Orbiter TPS, window protective covers and processing, natural landing site products, and paints/primers from various sources. The residual sampling data do not indicate a single source of damaging debris and all of these materials have been documented previously in analyses for post landing sample reports. Data from residual sampling also showed no trends when compared to previous mission data. A total of ten Post Launch Anomalies, including one IFA, were observed during the STS-62 mission assessment.

Katnik, Gregory N.↗

Search for a dark vector gauge boson decaying to π + π - using η → π + π - γ decays

In this report, we search for a dark vector gauge boson U ' that couples to quarks in the decay chain D * + → D 0 π + , D 0 → K S 0 η , η → U ' γ , U ' → π + π - . No signal is discovered and we set a mass-dependent limit on the baryonic fine structure constant of 10 - 3 - 10 - 2 in the U ' mass range of 290 to 520 MeV / c 2 . This analysis is based on a data sample of 976 fb - 1 collected by the Belle experiment at the KEKB asymmetric-energy e + e - collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Search for B + → K + τ + τ - at the BaBar Experiment

We search for the rare flavor-changing neutral current process B + → K + τ + τ - using data from the BABAR experiment. The data sample, collected at the center-of-mass energy of the Υ ( 4 S ) resonance, corresponds to a total integrated luminosity of 424 fb - 1 and to 471 × 1 0 6 B$\bar{B}$ pairs. We reconstruct one B meson, produced in the Υ ( 4 S ) → B + B - decay, in one of many hadronic decay modes and search for activity compatible with a B + → K + τ + τ - decay in the rest of the event. Each τ lepton is required to decay leptonically into an electron or muon and neutrinos. Comparing the expected number of background events with the data sample after applying the selection criteria, we do not find evidence for a signal. The resulting upper limit, at the 90% confidence level, is B ( B + → K + τ + τ - ) < 2.25 × 10 - 3 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Observation of D 0 - D ¯ 0 Mixing in e + e - Collisions

In this work, we observe D 0 - D ¯ 0 mixing in the decay D 0 → K + π - using a data sample of integrated luminosity 976 fb - 1 collected with the Belle detector at the KEKB e + e - asymmetric-energy collider. We measure the mixing parameters x ' 2 = ( 0.09 ± 0.22 ) × 1 0 - 3 and y ' = ( 4.6 ± 3.4 ) × 1 0 - 3 and the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates R D = ( 3.53 ± 0.13 ) × 1 0 - 3 , where the uncertainties are statistical and systematic combined. Our measurement excludes the no-mixing hypothesis at the 5.1 standard deviation level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Measurement of the Branching Fraction B ( Λ c + → p K - π + )

In this work, we present the first model-independent measurement of the absolute branching fraction of the Λ c + → p K - π + decay using a data sample of 978 fb - 1 collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. The number of Λ c + baryons is determined by reconstructing the recoiling D ( * ) - p ¯ π + system in events of the type e + e - → D ( * ) - p ¯ π + Λ c + . Lastly, the branching fraction is measured to be B ( Λ c + → p K - π + ) = ( 6.84 ± 0.24 - 0.27 + 0.21 ) % , where the first and second uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

End-to-End Jet Classification of Boosted Top Quarks with CMS Open Data

We describe a novel application of the end-to-end deep learning technique to the task of discriminating top quark-initiated jets from those originating from the hadronization of a light quark or a gluon. The end-to-end deep learning technique combines deep learning algorithms and low-level detector representation of the high-energy collision event. In this study, we use lowlevel detector information from the simulated CMS Open Data samples to construct the top jet classifiers. To optimize classifier performance we progressively add low-level information from the CMS tracking detector, including pixel detector reconstructed hits and impact parameters, and demonstrate the value of additional tracking information even when no new spatial structures are added. Relying only on calorimeter energy deposits and reconstructed pixel detector hits, the end-to-end classifier achieves a ROC-AUC score of 0.975±0.002 for the task of classifying boosted top quark jets. After adding derived track quantities, the classifier ROC-AUC score increases to 0.9824±0.0013, serving as the first performance benchmark for these CMS Open Data samples.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Measurement of the branching fraction of B + → τ + ν τ decays with the semileptonic tagging method

This report is a measurement of the branching fraction of B + → τ + ν τ decays using a data sample of 772 × 10 6 B B ¯ pairs, collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. We reconstruct the accompanying B meson in a semileptonic decay and detect the recoiling B candidate in the decay channel B + → τ + ν τ . We obtain a branching fraction of B ( B + → τ + ν τ ) = [ 1.25 ± 0.28 ( stat . ) ± 0.27 ( syst . ) ] × 10 - 4 . This result is in good agreement with previous measurements and the expectation from the calculation based on the Standard Model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

End-to-end jet classification of boosted top quarks with the CMS open data

Here we describe a novel application of the end-to-end deep learning technique to the task of discriminating top quark-initiated jets from those originating from the hadronization of a light quark or a gluon. The end-to-end deep learning technique uses low-level detector representation of high-energy collision event as inputs to deep learning algorithms. In this study, we use low-level detector information from the simulated Compact Muon Solenoid (CMS) open data samples to construct the top jet classifiers. To optimize classifier performance we progressively add low-level information from the CMS tracking detector, including pixel detector reconstructed hits and impact parameters, and demonstrate the value of additional tracking information even when no new spatial structures are added. Relying only on calorimeter energy deposits and reconstructed pixel detector hits, the end-to-end classifier achieves an area under the receiver operator curve (AUC) score of 0.975 ± 0.002 for the task of classifying boosted top quark jets. After adding derived track quantities, the classifier AUC score increases to 0.9824 ± 0.0013, serving as the first performance benchmark for these CMS open data samples.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Model-Independent Evidence for J / ψ p Contributions to Λ b 0 → J / ψ p K – Decays

The data sample of Λ 0 b → J/ψpK - decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb -1 , is inspected for the presence of J/ψp or J/ψK - contributions with minimal assumptions about K - p contributions. It is demonstrated at more than nine standard deviations that Λ 0 b → J/ψpK - decays cannot be described with K - p contributions alone, and that J/ψp contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P + c → J/ψp charmonium-pentaquark states in the same data sample.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Search for B + → e + ν e and B + → μ + ν μ decays using hadronic tagging

We present a search for the rare leptonic decays B + → e + ν e and B + → μ + ν μ , using the full Υ(4S) data sample of 772 × 10 6 BB¯ pairs collected with the Belle detector at the KEKB asymmetric-energy e + e – collider. One of the B mesons from the Υ(4S) → BB¯ decay is fully reconstructed in a hadronic mode, while the recoiling side is analyzed for the signal decay. Here, we find no evidence of a signal in any of the decay modes. Upper limits of the corresponding branching fractions are determined as B(B + → e + ν e ) < 3.5 × 10 –6 and B(B + → μ + ν μ ) < 2.7 × 10 –6 at 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Search for a heavy neutral lepton that mixes predominantly with the tau neutrino

We report a search for a heavy neutral lepton (HNL) that mixes predominantly with ν τ . The search utilizes data collected with the Belle detector at the KEKB asymmetric energy e + e − collider. The data sample was collected at and just below the center-of-mass energies of the ϒ ( 4 S ) and ϒ ( 5 S ) resonances and has an integrated luminosity of 915 fb − 1 , corresponding to ( 836 ± 12 ) × 10 6 e + e − → τ + τ − events. We search for production of the HNL (denoted N ) in the decay τ − → π − N followed by its decay via N → μ + μ − ν τ . The search focuses on the parameter-space region in which the HNL is long-lived, so that the μ + μ − originate from a common vertex that is significantly displaced from the collision point of the KEKB beams. Consistent with the expected background yield, one event is observed in the data sample after application of all the event-selection criteria. We report limits on the mixing parameter of the HNL with the τ neutrino as a function of the HNL mass. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

Measurement of the branching fraction and C P asymmetry in B 0 → π 0 π 0 decays, and an improved constraint on φ 2

Here, we measure the branching fraction and C P violation asymmetry in the decay B 0 → π 0 π 0 , using a data sample of 752 × 10 6 B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB e + e - collider. The obtained branching fraction and direct C P asymmetry are B ( B → π 0 π 0 ) = [ 1.31 ± 0.19 ( stat ) ± 0.19 ( syst ) ] × 10 - 6 and A C P = + 0.14 ± 0.36 ( stat ) ± 0.10 ( syst ) , respectively. The signal significance, including the systematic uncertainty, is 6.4 standard deviations. Furthemore, we combine these results with Belle’s earlier measurements of B 0 → π + π - and B ± → π ± π 0 to exclude the C P -violating parameter φ 2 from the range 15.5 ° < φ 2 < 75.0 ° at 95% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Recombination of NO/+/ in the mid-latitude trough and the polar ionization hole

The dissociative recombination of NO(+) with electrons is further examined using a sample of Atmosphere Explorer data from the midlatitude ionization trough. The electron temperature for this data sample covered a range of 2500 K, thus allowing an accurate determination of the temperature dependence of the rate coefficient. The results confirm earlier determinations which were made from a large data base, and the rate coefficient alpha is found to be inversely proportional to the electron temperature. The possibility of a neglected process in the NO(+) chemistry is investigated which, if it were included, might result in a smaller temperature dependence of alpha. Such a source would require a direct dependence on electron temperature. A possible candidate is associative recombination of energetic N(D-2) with O. The results confirm recent measurements which find that this process cannot be significant. The NO(+) chemistry is a very sensitive indicator of chemical equilibrium conditions. By using measurements of the relevant parameters made in the polar ionization hole it is found that horizontal drifts do not appear to be significant in this region.

Torr, M. R.↗

Observation of X ( 3872 ) in B → X ( 3872 ) K π decays

We report the first observation of B 0 →X(3872)(K + π – ) and evidence for B + → X(3872)(K 0 π + ). We measure the product of branching fractions for the former to be B(B 0 → X(3872)(K + π – )) × B(X(3872) → J/ψπ + π – ) = (7.9 ± 1.3(stat) ± 0.4(syst)) × 10 –6 and find that B 0 → X(3872)K*(892) 0 does not dominate the B 0 → X(3872)K + π – decay mode. We also measure B(B + → X(3872)(K 0 π + )) × B(X(3872) → J/ψπ + π – ) = (10.6 ± 3.0(stat) ± 0.9(syst)) × 10 –6 . Furthermore, this study is based on the full data sample of 711 fb –1 (772 × 10 6 BB¯ pairs) collected at the Υ(4S) resonance with the Belle detector at the KEKB collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Evidence for semileptonic B - → p p ¯ ℓ - ν ¯ ℓ decays

Evidence for the semileptonic baryonic decay B - → p p ¯ ℓ - ν ¯ ℓ ( ℓ = e , μ ), based on a data sample of 772 million B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy electron-positron collider is collected. A neural-network based hadronic B -meson tagging method is used in this study. The branching fraction of B - → p p ¯ ℓ - ν ¯ ℓ is measured to be ( 5. 8 - 2.1 + 2.4 (stat) ± 0.9 (syst) ) × 10 - 6 with a significance of 3.2 σ , where lepton universality is assumed. We also estimate the corresponding upper limit: B ( B - → p p ¯ ℓ - ν ¯ ℓ ) < 9.6 × 10 - 6 at the 90% confidence level. This measurement helps constrain the baryonic transition form factor in B decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Observation of B 0 → p Λ ¯ D ( * ) -

We report the first observation of the decays B 0 →p$\bar{Λ}$D(*)-. The data sample of 711 fb -1 used in this analysis corresponds to 772 million $B$$\bar{B}$ pairs, collected at the Υ(4S) resonance by the Belle detector at the KEKB asymmetric-energy e + e - collider. We observe 19.8σ and 10.8σ excesses of events for the two decay modes and measure the branching fractions of B 0 →p$\bar{Λ}$D- and B 0 →p$\bar{Λ}$D(*)- to be (25.1±2.6±3.5)×10 -6 and (33.6±6.3±4.4)×10 -6 , respectively, where the first uncertainties are statistical and the second are systematic. These results are not compatible with the predictions based on the generalized factorization approach. In addition, a threshold enhancement in the di-baryon (p$\bar{Λ}$) system is observed, consistent with that observed in similar B decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Search for the 0 - - glueball in Υ ( 1 S ) and Υ ( 2 S ) decays

Here, we report the first search for the J P C = 0 - - glueball in Υ ( 1 S ) and Υ ( 2 S ) decays with data samples of ( 102 ± 2 ) × 1 0 6 and ( 158 ± 4 ) × 1 0 6 events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90% credibility level upper limits on their branching fractions in Υ ( 1 S ) and Υ ( 2 S ) decays are gained. The inclusive branching fractions of the Υ ( 1 S ) and Υ ( 2 S ) decays into final states with a χ c 1 are measured to be B ( Υ ( 1 S ) → χ c 1 + anything ) = ( 1.90 ± 0.43 ( stat ) ± 0.14 ( syst ) ) × 10 - 4 with an improved precision over prior measurements and B ( Υ ( 2 S ) → χ c 1 + anything ) = ( 2.24 ± 0.44 ( stat ) ± 0.20 ( syst ) ) × 10 - 4 for the first time.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗