Photoproduction of pi+ pi- pairs in a model with tensor-pomeron and vector-odderon exchange

We consider the reaction (gamma p) to (pi+ pi- p) at high energies. Our description includes dipion production via the resonances rho, omega, rho-prime and f2, and via non-resonant mechanisms. The calculation is based on a model of high energy scattering with the exchanges of photon, pomeron, odderon and reggeons. The pomeron and the C=+1 reggeons are described as effective tensor exchanges, the odderon and the C=-1 reggeons as effective vector exchanges. We obtain a gauge-invariant version of the Drell-Soeding mechanism which produces the skewing of the rho-meson shape. Starting from the explicit formulae for the matrix element for dipion production we construct an event generator which comprises all contributions mentioned above and includes all interference terms. We give examples of total and differential cross sections and discuss asymmetries which are due to interference of C=+1 and C=-1 exchange contributions. These asymmetries can be used to search for odderon effects. Our model is intended to provide all necessary theoretical tools for a detailed experimental analysis of elastic dipion production for which data exist from fixed target experiments, from HERA, and are now being collected by LHC experiments.Comment: 49 page

Measurement of Differential ρ0 Photoproduction Cross-Sections at HERA

Exclusive photoproduction of ρ 0 vector mesons is studied with the H1 detector at HERA. A sample of over 900 000 π + π − photoproduction events was collected in the years 2006-2007 using the H1 Fast Track Trigger. It corresponds to an integrated luminosity of 1.3 pb −1 . The dataset is used to study single-, double-, and triple-differential π + π − photoproduction cross-sections as a function of the invariant mass of the pions m ππ , the photon-proton collision energy W γp , and the squared momentum transfer at the proton vertex t. The phasespace is restricted to 0.5 GeV < m ππ < 2.2 GeV, 20 GeV < W γp < 80 GeV, −t < 1.5 GeV 2 , and a photon virtuality Q 2 < 0.1 GeV 2 . Reactions in which the scattered proton stays intact are statistically separated from those where it dissociates to a low-mass hadronic system in the range m p < m Y < 10 GeV. The m ππ distributions are parametrized by a Söding model to extract the ρ 0 contribution to π + π − production. Single- and double-differential ρ 0 cross-sections are measured as a function of W γp and t. The observed kinematic cross-section dependencies are parametrized using őts and are compared to expectations from phenomenological models as well as results from previous measurements. From the double-differential ρ 0 cross-section, the effective intercept and slope of the leading Regge trajectory in the measurement phasespace are extracted: α(t = 0) = 1.0659 ± 0.0033 (stat.) +0.0099/−0.0059 (syst.) α (t = 0) = 0.243 ± 0.050 (stat.) +0.030/−0.042 (syst.) GeV −2

Identification of novel mutations in X-linked retinitis pigmentosa families and implications for diagnostic testing

Contains fulltext : 69886.pdf (publisher's version ) (Open Access)PURPOSE: The goal of this study was to identify mutations in X-chromosomal genes associated with retinitis pigmentosa (RP) in patients from Germany, The Netherlands, Denmark, and Switzerland. METHODS: In addition to all coding exons of RP2, exons 1 through 15, 9a, ORF15, 15a and 15b of RPGR were screened for mutations. PCR products were amplified from genomic DNA extracted from blood samples and analyzed by direct sequencing. In one family with apparently dominant inheritance of RP, linkage analysis identified an interval on the X chromosome containing RPGR, and mutation screening revealed a pathogenic variant in this gene. Patients of this family were examined clinically and by X-inactivation studies. RESULTS: This study included 141 RP families with possible X-chromosomal inheritance. In total, we identified 46 families with pathogenic sequence alterations in RPGR and RP2, of which 17 mutations have not been described previously. Two of the novel mutations represent the most 3'-terminal pathogenic sequence variants in RPGR and RP2 reported to date. In exon ORF15 of RPGR, we found eight novel and 14 known mutations. All lead to a disruption of open reading frame. Of the families with suggested X-chromosomal inheritance, 35% showed mutations in ORF15. In addition, we found five novel mutations in other exons of RPGR and four in RP2. Deletions in ORF15 of RPGR were identified in three families in which female carriers showed variable manifestation of the phenotype. Furthermore, an ORF15 mutation was found in an RP patient who additionally carries a 6.4 kbp deletion downstream of the coding region of exon ORF15. We did not identify mutations in 39 sporadic male cases from Switzerland. CONCLUSIONS: RPGR mutations were confirmed to be the most frequent cause of RP in families with an X-chromosomal inheritance pattern. We propose a screening strategy to provide molecular diagnostics in these families

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Status of the BELLE II Pixel Detector

The Belle II experiment at the super KEK B-factory (SuperKEKB) in Tsukuba, Japan, has been collecting $e^+e^−$ collision data since March 2019. Operating at a record-breaking luminosity of up to $4.7×10^{34} cm^{−2}s^{−1}$, data corresponding to $424 fb^{−1}$ has since been recorded. The Belle II VerteX Detector (VXD) is central to the Belle II detector and its physics program and plays a crucial role in reconstructing precise primary and decay vertices. It consists of the outer 4-layer Silicon Vertex Detector (SVD) using double sided silicon strips and the inner two-layer PiXel Detector (PXD) based on the Depleted P-channel Field Effect Transistor (DePFET) technology. The PXD DePFET structure combines signal generation and amplification within pixels with a minimum pitch of $(50×55) μm^2$. A high gain and a high signal-to-noise ratio allow thinning the pixels to $75 μm$ while retaining a high pixel hit efficiency of about $99$. As a consequence, also the material budget of the full detector is kept low at $≈0.21$$\frac{X}{X_0}$ per layer in the acceptance region. This also includes contributions from the control, Analog-to-Digital Converter (ADC), and data processing Application Specific Integrated Circuits (ASICs) as well as from cooling and support structures. This article will present the experience gained from four years of operating PXD; the first full scale detector employing the DePFET technology in High Energy Physics. Overall, the PXD has met the expectations. Operating in the intense SuperKEKB environment poses many challenges that will also be discussed. The current PXD system remains incomplete with only 20 out of 40 modules having been installed. A full replacement has been constructed and is currently in its final testing stage before it will be installed into Belle II during the ongoing long shutdown that will last throughout 2023

Charge Asymmetries in π+π−\pi{+} \pi^{-} Photoproduction in a Model for Soft High Energy Scattering and Detector Asymmetry Measurements at the H1 Experiment

Charge asymmetries in$\pi{+} \pi^{-}$ photoproduction are studied in a model for soft high energy scattering processes. $\pi{+} \pi^{-}$ photoproduction at high center of mass energies is dominated by the exchange of the pomeron with even charge conjugation quantum number C. It is investigated that already small contributions from exchange particles with odd C-parity result in asymmetries in the angular distributions of the pions. C-odd contributions come from photon, and possibly also from odderon exchange. The odderon is the leading exchange particle in soft high energy scattering with odd C-parity but has not been observed yet. Thus measuring charge asymmetries in $\pi{+} \pi^{-}$ photoproduction can help establish its existence experimentally.As a part of efforts to measure charge asymmetries in $\pi{+} \pi^{-}$ photoproduction at the H1-experiment at the HERA collider, an evaluation of detector effects that may cause charge asymmetries is performed. A focus is put on studying the performance the Fast Track Trigger, which is used to trigger photoproduction events at H1. Several detector effects, most importantly geometric detectorasymmetries that are not considered on the trigger level, are shown to give rise to charge asymmetries in the trigger efficiency. It is verified that all effects are correctly described in the detector simulation and can thus be accounted for in an asymmetry measurement

Measurement of Exclusive ρ0\rho^{0} Meson Photoproduction at HERA

Exclusive photoproduction of ρ(770) vector mesons is studied using the H1 detector at HERA. A sample of about 700000 decays ρ→π+π− was collected in the years 2006-2007, using the H1 fast track trigger. It corresponds to an integrated luminosity of 1.3 pb−1. The sample is used to study cross-sections as a function of the invariant mass mππ of the decay pions, the photon-proton collision energy W and the momentum transfer at the proton vertex t. The phase-space restrictions are 0.5<mππ<1.3 GeV, 20<W<80 GeV and |t|<1.5 GeV2. Reactions where the proton stays intact are statistically separated from those where the proton dissociates to a low-mass hadronic system. The observed cross-section dependencies are parameterized using fits and are compared to expectations from phenomenological models

Measurement of ρ(770)\rho(770) photoproduction at HERA

Exclusive photoproduction of (770) mesons is studied using the H1 detector at HERA. The analysis is based on a sample of about 900000 events that were collected in the years 2006-2007. It is used to measure single- and double-differential cross sections for the reaction →+−. Reactions where the proton stays intact (=) are statistically separated from those where the proton dissociates to a low-mass hadronic system (<<10 GeV). The double differential cross sections are measured as a function of the invariant mass of the decay pions and the squared momentum transfer at the proton vertex . These measurements are repeated in bins of the photon-proton collision energy . The phase-space restrictions are 0.5<<2.2 GeV, ||<1.5 GeV2 and 20<<80 GeV. Cross-section measurements are presented for both elastic and dissociative scattering. The observed kinematic dependencies are described by analytic functions. In particular, a Soding model is used to extract the (770) contribution to the +− cross-sections. From the resulting single-differential (770) cross-section as a function of , measured in bins of , the leading effective Regge trajectory is extracted