Search

This paper presents a world-leading scintillation light yield among inorganic crystals measured from a 0.5 kg pure-CsI detector operated at 77 Kelvin. Scintillation photons were detected by two 2-inch Hamamatsu SiPM arrays equipped with cryogenic front-end electronics. Benefiting the light yield enhancement of pure-CsI at low temperatures and the high photon detection efficiency of SiPM, a light yield of 30.1 photoelectrons per keV energy deposit was obtained for X-rays and γ -rays with energies from 5.9 to 59.6 keV. Instrumental and physical effects in the light yield measurement are carefully analyzed. This is the first stable cryogenic operation of kg-scale pure-CsI crystal readout by SiPM arrays at liquid nitrogen temperatures for several days. The world-leading light yield opens a door for the usage of pure-CsI crystal in several fields, particularly in detecting the coherent elastic neutrino-nucleus scattering of reactor neutrinos. The potential of using pure-CsI crystals in neutrino physics is discussed in the paper. [ABSTRACT FROM AUTHOR]

We present our first set of results for charm physics, using the mixed-action setup introduced in a companion paper [1]. Maximally twisted Wilson valence fermions are used on a sea of non-perturbatively O(a)-improved Wilson fermions, made up by CLS N f = 2 + 1 ensembles. Our charm-sector observables are free from O (a m c) discretisation effects, without need of tuning any improvement coefficient, and show continuum-limit scaling properties consistent with leading cutoff effects of O (a 2) . We consider a subset of CLS ensembles – including four values of the lattice spacing and pion masses down to 200 MeV – allowing to take the continuum limit and extrapolate to the physical pion mass. A number of techniques are incorporated in the analysis in order to estimate the systematic uncertainties of our results for the charm quark mass and the D (s) -meson decay constants. This first study of observables in the charm sector, where the emphasis has been on the control of the methodology, demonstrates the potential of our setup to achieve high-precision results. [ABSTRACT FROM AUTHOR]

The prospects are presented for precise measurements of the branching ratios of the purely leptonic B c + → τ + ν τ and B + → τ + ν τ decays at the Future Circular Collider (FCC). This work is focused on the hadronic τ + → π + π + π - ν ¯ τ decay in both B c + → τ + ν τ and B + → τ + ν τ processes. Events are selected with two Boosted Decision Tree algorithms to optimise the separation between the two signal processes as well as the generic hadronic Z decay backgrounds. The range of the expected precision for both signals are evaluated in different scenarios of non-ideal background modelling. This paper demonstrates, for the first time, that the B + → τ + ν τ decay can be well separated from both B c + → τ + ν τ and generic Z → b b ¯ processes in the FCC-ee collision environment and proposes the corresponding branching ratio measurement as a novel way to determine the CKM matrix element | V ub | . The theoretical impacts of both B + → τ + ν τ and B c + → τ + ν τ measurements on New Physics cases are discussed for interpretations in the generic Two-Higgs-doublet model and leptoquark models. [ABSTRACT FROM AUTHOR]

In this paper we employ a recent proposal of C. Tsallis and formulate the first law of thermodynamics for gravitating systems in terms of the extensive but non-additive entropy. We pay a particular attention to an integrating factor for the heat one-form and show that in contrast to conventional thermodynamics it factorizes into thermal and entropic part. Ensuing two laws of thermodynamics imply Tsallis cosmology, which is then subsequently used to address the observed discrepancy between current bound on the Dark Matter relic abundance and present IceCube data on high-energy neutrinos. To resolve this contradiction we keep the conventional minimal Yukawa-type interaction between standard model and Dark Matter particles but replace the usual Friedmann field equations with Tsallis-cosmology-based modified Friedmann equations. We show that when the Tsallis scaling exponent δ ∼ 1.57 (or equivalently, the holographic scaling exponent α ∼ 3.13 ) the aforementioned discrepancy disappears. [ABSTRACT FROM AUTHOR]

In this paper, using the Bestest Little Higgs Model (BLHM) we calculate at the one-loop level the contributions to the Anomalous Magnetic Dipole Moment (AMDM) and Anomalous Weak Magnetic Dipole Moment (AWMDM) of the tau-lepton. The implications from this model are studied, emphasizing the contributions of the new physics induced by the new scalar and vector bosons of the BLHM: S i = H 0 , A 0 , ϕ 0 , η 0 , σ , H ± , ϕ ± , η ± , and V i = Z ′ , W ′ ± because these quantify the new physics. With these new contributions, we estimated bounds on the real and imaginary parts of the AMDM and AWMDM of the tau-lepton. Our study complements other one-loop-level research performed on models beyond the Standard Model. [ABSTRACT FROM AUTHOR]

This paper is an addendum to Ref. Eur. Phys. J. C79 (2019) no. 8, 714 that supersedes all results (Tables and Figures) in that paper after including the new data on the B → K ∗ μ μ angular distribution released in 2020 by the LHCb collaboration. The new results confirm all the conclusions in Eur. Phys. J. C79 (2019) no. 8, 714, exhibiting an increase in the coherence and significance of the hypotheses and confirming the existence of a puzzle. [ABSTRACT FROM AUTHOR]

The muon g - 2 anomaly was strengthened by recent experimental results at Fermilab, which may be signatures of new physics. A scenario of leptophilic scalar ϕ L accounting for the muon g - 2 anomaly is investigated in this paper. Although a light ϕ L mainly decaying into standard model (SM) particles has been excluded by experiments, a dark leptophilic scalar ϕ L predominantly decaying into invisible fermionic dark matter (DM) χ χ ¯ is still allowed. Considering the decay mode ϕ L → χ χ ¯ opened (here m ϕ L = 3 m χ ), the coupling preferred by the muon g - 2 and the ϕ L - χ coupling are derived. The light/heavy ϕ L (roughly 1 GeV as a benchmark value) can be tested by future experiments via DM/SM decay modes, and the contribution of ϕ L to the anomalous magnetic moment of the tau lepton could be investigated at lepton colliders. The search for χ via χ -electron scattering in direct detection of DM is not sensitive due to a tiny ϕ L -electron coupling, especially for m χ ≳ m μ . [ABSTRACT FROM AUTHOR]

In this paper we describe the implementation of the charged current decays of the type t→bl+νl(γ) in the framework of the SANC system. All calculations are done taking into account the one-loop electroweak correction in the standard model. The emphasis of this paper is on the presentation of numerical results. Various distributions are produced by means of a Monte Carlo integrator and event generator. Comparison with the results of the CompHEP and PYTHIA packages are presented for the Born and hard photon contributions. The validity of the cascade approximation at one-loop level is also studied. [ABSTRACT FROM AUTHOR]

In this paper, we present the physics performance of the ESSnuSB experiment in the standard three flavor scenario using the updated neutrino flux calculated specifically for the ESSnuSB configuration and updated migration matrices for the far detector. Taking conservative systematic uncertainties corresponding to a normalization error of 5 % for signal and 10 % for background, we find that there is 10 σ (13 σ) CP violation discovery sensitivity for the baseline option of 540 km (360 km) at δ CP = ± 90 ∘ . The corresponding fraction of δ CP for which CP violation can be discovered at more than 5 σ is 70 % . Regarding CP precision measurements, the 1 σ error associated with δ CP = 0 ∘ is around 5 ∘ and with δ CP = - 90 ∘ is around 14 ∘ (7 ∘) for the baseline option of 540 km (360 km). For hierarchy sensitivity, one can have 3 σ sensitivity for 540 km baseline except δ CP = ± 90 ∘ and 5 σ sensitivity for 360 km baseline for all values of δ CP . The octant of θ 23 can be determined at 3 σ for the values of: θ 23 > 51 ∘ ( θ 23 < 42 ∘ and θ 23 > 49 ∘ ) for baseline of 540 km (360 km). Regarding measurement precision of the atmospheric mixing parameters, the allowed values at 3 σ are: 40 ∘ < θ 23 < 52 ∘ ( 42 ∘ < θ 23 < 51. 5 ∘ ) and 2.485 × 10 - 3 eV 2 < Δ m 31 2 < 2.545 × 10 - 3 eV 2 ( 2.49 × 10 - 3 eV 2 < Δ m 31 2 < 2.54 × 10 - 3 eV 2 ) for the baseline of 540 km (360 km). [ABSTRACT FROM AUTHOR]

Long-lived particles have become a new frontier in the exploration of physics beyond the Standard Model. In this paper, we present the implementation of four types of long-lived particle searches, viz. displaced leptons, disappearing track, displaced vertex with either muons or with missing transverse energy, and heavy charged tracks. These four categories cover the signatures of a large range of physics models. We illustrate their potential for exclusion and discuss their mutual overlaps in mass-lifetime space for two simple phenomenological models involving either a U(1)-charged or a coloured scalar. [ABSTRACT FROM AUTHOR]

Higgs-portal effective field theories are widely used as benchmarks in order to interpret collider and astroparticle searches for dark matter (DM) particles. To assess the validity of these effective models, it is important to confront them to concrete realizations that are complete in the ultraviolet regime. In this paper, we compare effective Higgs-portal models with scalar, fermionic and vector DM with a series of increasingly complex realistic models, taking into account all existing constraints from collider and astroparticle physics. These complete realizations include the inert doublet with scalar DM, the singlet-doublet model for fermionic DM and models based on spontaneously broken dark SU(2) and SU(3) gauge symmetries for vector boson DM. We also discuss the simpler scenarios in which a new scalar singlet field that mixes with the standard Higgs field is introduced with minimal couplings to isosinglet spin- 0 , 1 2 and 1 DM states. We show that in large regions of the parameter space of these models, the effective Higgs-portal approach provides a consistent limit and thus, can be safely adopted, in particular for the interpretation of searches for invisible Higgs boson decays at the LHC. The phenomenological implications of assuming or not that the DM states generate the correct cosmological relic density are also discussed. [ABSTRACT FROM AUTHOR]

Searching for the new particles beyond the standard model (SM) is an important way to probe new physics beyond the SM. In one class of new particles there are nonchiral color singlet fermions that couple to the SM leptons, that is vector-like leptons (VLLs), which have been widely concerned in experiment and theory. The existing literature shows that the singlet VLLs suffer from a big difficult challenge for discovery at future proton-proton colliders. In this paper, we study the prospects of searching for the singlet VLLs in pure leptonic and fully hadronic channels at e + e - colliders. We find that there is an opportunity for excluding the region m τ ′ ± ∈ [180 GeV, 240 GeV] with L ∈ [ 3.0 fb - 1 , 14.9 fb - 1 ] ([ 0.1 fb - 1 , 0.3 fb - 1 ]) at ILC of s = 500 GeV , the region m τ ′ ± ∈ [240 GeV, 450 GeV] with L ∈ [ 9.9 fb - 1 , 23.1 fb - 1 ] ([ 0.2 fb - 1 , 0.3 fb - 1 ]) at ILC of s = 1000 GeV and the region m τ ′ ± ∈ [450 GeV, 700 GeV] with L ∈ [ 52.1 fb - 1 , 197.9 fb - 1 ] ([ 2.21 fb - 1 , 4.5 fb - 1 ]) at CLIC of s = 1500 GeV in the pure leptonic (fully hadronic) channel. It is more optimistic for excluding and discovering the singlet VLL through the fully hadronic channel at future high energy e + e - colliders. [ABSTRACT FROM AUTHOR]

A general analysis of possible violation of CP in processes like τ → K π ν , for unpolarized τ is presented. In this paper, we derive the new contributions to the effective Hamiltonian governs | Δ S | = 1 semileptonic tau decays in the framework of two Higgs doublet model with generic Yukawa structure and Leptoquarks models. Within these models, we list all operators, in the effective Hamiltonian and provide analytical expression for their corresponding Wilson coefficients. Moreover, we analyze the role of the different contributions, originating from the scalar, vecor and tensor hadronic currents, in generating direct CP asymmetry in the decay rate of τ - → K - π 0 ν τ . We show that non vanishing direct CP asymmetry in the decay rate of τ - → K - π 0 ν τ can be generated due to the presence of both, the weak phase in the Wilson coefficient corresponding to the tensor operator and the strong phase difference resulting from the interference between the form factors expressing the matrix elements of the vector and tensor hadronic currents. After taking into account all relevant constraints, we find that the generated direct CP asymmetry is of order 10 - 8 which is several orders of magnitude larger than the standard model prediction. We show also that, in two Higgs doublet model with generic Yukawa structure , direct local or non integrated CP violation can be as large as 0.3 % not far from experimental possibilities. This kind of asymmetry can be generated due to the interference between vector and scalar contributions with different weak phases which is not the case in the SM. [ABSTRACT FROM AUTHOR]

The Deep Underground Neutrino Experiment (DUNE) will be a powerful tool for a variety of physics topics. The high-intensity proton beams provide a large neutrino flux, sampled by a near detector system consisting of a combination of capable precision detectors, and by the massive far detector system located deep underground. This configuration sets up DUNE as a machine for discovery, as it enables opportunities not only to perform precision neutrino measurements that may uncover deviations from the present three-flavor mixing paradigm, but also to discover new particles and unveil new interactions and symmetries beyond those predicted in the Standard Model (SM). Of the many potential beyond the Standard Model (BSM) topics DUNE will probe, this paper presents a selection of studies quantifying DUNE's sensitivities to sterile neutrino mixing, heavy neutral leptons, non-standard interactions, CPT symmetry violation, Lorentz invariance violation, neutrino trident production, dark matter from both beam induced and cosmogenic sources, baryon number violation, and other new physics topics that complement those at high-energy colliders and significantly extend the present reach. [ABSTRACT FROM AUTHOR]

A search in an all-jet final state for new massive resonances decaying to W W , W Z , or Z Z boson pairs using a novel analysis method is presented. The analysis is performed on data corresponding to an integrated luminosity of 77.3 fb - 1 recorded with the CMS experiment at the LHC at a centre-of-mass energy of 13 Te . The search is focussed on potential narrow-width resonances with masses above 1.2 Te , where the decay products of each W or Z boson are expected to be collimated into a single, large-radius jet. The signal is extracted using a three-dimensional maximum likelihood fit of the two jet masses and the dijet invariant mass, yielding an improvement in sensitivity of up to 30% relative to previous search methods. No excess is observed above the estimated standard model background. In a heavy vector triplet model, spin-1 Z ′ and W ′ resonances with masses below 3.5 and 3.8 Te , respectively, are excluded at 95% confidence level. In a bulk graviton model, upper limits on cross sections are set between 27 and 0.2 fb for resonance masses between 1.2 and 5.2 Te , respectively. The limits presented in this paper are the best to date in the dijet final state. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the existence and time evolution of the cosmological and event horizons in a McVittie universe whose expansion is driven by the Redlich–Kwong, (Modified) Berthelot, Dieterici, and Peng–Robinson fluids, respectively. The equations of state of these fluids are rich enough to account for both exotic and regular, as well as ideal and non-ideal matter contents of the universe. We show that the cosmological horizon is expanding, while the event horizon is shrinking along the cosmic time evolution. The former achieves larger size for regular types of matter, contrary to the latter. The strength of interactions within the cosmic fluid are shown to play a more important role in affecting the evolution of the event horizon, rather than of the cosmological horizon in the case of a singularity-free universe. While the cosmological horizon always exists during the time evolution, the event horizon can exist only when a certain relationship between the Hawking–Hayward quasi-local mass and the Hubble function is fulfilled. In this manner, we can study the role played by the large-scale physics (cosmic evolution) on the local scale physics (evolution of a black hole). [ABSTRACT FROM AUTHOR]

A Correction to this paper has been published: 10.1140/epjc/s10052-021-09420-1 [ABSTRACT FROM AUTHOR]

A Correction to this paper has been published: https://doi.org/10.1140/epjc/s10052-020-7621-7. [ABSTRACT FROM AUTHOR]

The Bayes factor surface is a new way to present results from experimental searches for new physics. Searches are regularly expressed in terms of phenomenological parameters – such as the mass and cross-section of a weakly interacting massive particle. Bayes factor surfaces indicate the strength of evidence for or against models relative to the background only model in terms of the phenomenological parameters that they predict. They provide a clear and direct measure of evidence, may be easily reinterpreted, but do not depend on choices of prior or parameterization. We demonstrate the Bayes factor surface with examples from dark matter, cosmology, and collider physics. [ABSTRACT FROM AUTHOR]

In this work, we will study the late-time dynamic evolution of the F(R) gravity dark energy model of an interaction between dark radiation and dark matter. We explore the possibility of the apparent extra dark radiation being linked directly to the physics of cold dark matter (CDM). In particular, we consider a generic scenario where dark radiation, as a result of an interaction, is produced directly by a fraction of the dark matter density effectively decaying into dark radiation. The decay process is controlled by its rate Q = α H ρ dm , where α is the (constant) dimensionless parameter quantifying the strength of the decay mechanism, for the weak coupling between dark matter and dark radiation α ≪ 1 . We will solve the field equations numerically by using the statefinder function y H to appropriately represent the field equation. The F(R) gravity model we consider is described by a nearly R 2 -model at early epochs and at late-time the model mimic the Λ -Cold-Dark-Matter model ( Λ C D M ), and we fine tune the parameters to achieve viability and compatibility with the latest Planck constraints at late-time. Furthermore, we consider the behavior of several well-known statefinder quantities, we find that statefinder diagnostic and Om diagnostic can not only break the degeneracy of different parameter values in the F(R) gravity dark energy model, but also effectively distinguish the difference between the F(R) gravity model and the Λ C D M model. At last, we compared the theoretical results with the SNIa data. [ABSTRACT FROM AUTHOR]

In this paper we propose a strategy for measuring the inclusive W boson production processes at LHC. This strategy exploits simultaneously the unique flexibility of the LHC collider in running variable beam particle species at variable beam energies, and the configuration flexibility of the LHC detectors. We propose their concrete settings for a precision measurement of the standard model parameters. These dedicated settings optimise the use of the Z boson and Drell–Yan-pair production processes as “the standard reference candles”. The presented strategy allows one to factorise and to directly measure those of the QCD effects that affect differently the W and Z production processes. It reduces to a level of $\mathcal{O}(10^{-4})$ the impact of uncertainties in the partonic distribution functions (PDFs) and in the transverse momentum of the quarks on the measurement precision. Last but not the least, it reduces by a factor of 10 the impact of systematic measurement errors, such as the energy scale and the measurement resolution, on the W boson production observables. [ABSTRACT FROM AUTHOR]

In this paper we study dynamical CPT-violation in the neutrino sector as induced by the dark energy of the universe. Specifically we consider a dark energy model where the dark energy scalar derivatively interacts with the right-handed neutrinos. This type of derivative coupling leads to cosmological CPT-violation during the evolution of the background field of the dark energy. We calculate the induced CPT-violation of left-handed neutrinos and find that the CPT-violation produced in this way is consistent with the present experimental limit and sensitive to future neutrino oscillation experiments such as the neutrino factory. [ABSTRACT FROM AUTHOR]

Charged particle multiplicities in A+A and p(p̄)+p collisions as a function of pseudorapidity, centrality and energy are studied in both the nucleon and the constituent quark frameworks. In the present work, the calculation using the nuclear overlap model takes into account the fact that for the peripheral A+A and p+p collisions the number of nucleon and constituent quark participants cannot be smaller than two. A striking agreement is seen between the particle density in A+A and p(p̄)+p collisions, both at mid-rapidity and in the fragmentation regions, when normalized to the number of participating constituent quarks. The observations presented in this paper imply that the number of constituent quark pairs participating in the collision controls the particle production. [ABSTRACT FROM AUTHOR]

In this paper we discuss the survival probability for exclusive central diffractive production of a colorless small size system at the LHC. This process has the clear signature of two large rapidity gaps. Using the eikonal approach for the description of soft interactions, we predict the value of the survival probability to be about 5∼6% for single channel models, while for a two channel model the survival probability is about 3%. The dependence of the survival probability factor (damping factor) on the transverse momenta of the recoiled protons is discussed, and we suggest that it be measured at the Tevatron so as to minimize the possible ambiguity in the calculation of the survival probability at the LHC. [ABSTRACT FROM AUTHOR]

We determine the nilpotent BRST and anti-BRST transformations for the Cho-Faddeev-Niemi variables for the $SU\!(2)$ Yang-Mills theory based on the new interpretation given in a previous paper of the Cho-Faddeev-Niemi decomposition. This gives a firm ground for performing the BRST quantization of the Yang-Mills theory written in terms of the Cho-Faddeev-Niemi variables. We propose also a modified version of the new maximal Abelian gauge which could play an important role in the reduction to the original Yang-Mills theory. [ABSTRACT FROM AUTHOR]

We present a full treatment of the microcanonical ensemble of the ideal hadron-resonance gas starting from a quantum-mechanical formulation which is appropriate for the statistical model of hadronization. By using a suitable transition operator for hadronization we are able to recover the results of the statistical theory, particularly the expressions of the rates of different channels. Explicit formulae are obtained for the phase space volume or density of states of the ideal relativistic gas in quantum statistics as a cluster decomposition, generalizing previous ones in the literature. The problem of the computation of averages in the hadron gas microcanonical ensemble and the comparison with canonical ones will be the main subject of a forthcoming second paper. [ABSTRACT FROM AUTHOR]

Compact abelian gauge theories in d=2+1 dimensions arise often as an effective field-theoretic description of models of quantum insulators. In this paper we review some recent results about the compact abelian Higgs model in d=2+1 in that context. PACS: 11.15.Ha Lattice gauge theory – 11.10.Kk Field theories in dimensions other than four [ABSTRACT FROM AUTHOR]

In recent years, theoretical and phenomenological studies with effective field theories have become a trending and prolific line of research in the field of high-energy physics. In order to discuss present and future prospects concerning automated tools in this field, the SMEFT-Tools 2022 workshop was held at the University of Zurich from 14th–16th September 2022. The current document collects and summarizes the content of this workshop. [ABSTRACT FROM AUTHOR]

In this work we present PRyMordial: A package dedicated to efficient computations of observables in the Early Universe with the focus on the cosmological era of Big Bang Nucleosynthesis (BBN). The code offers fast and precise evaluation of BBN light-element abundances together with the effective number of relativistic degrees of freedom, including non-instantaneous decoupling effects. PRyMordial is suitable for state-of-the-art analyses in the Standard Model as well as for general investigations into New Physics active during BBN. After reviewing the physics implemented in PRyMordial, we provide a short guide on how to use the code for applications in the Standard Model and beyond. The package is written in Python, but more advanced users can optionally take advantage of the open-source community for Julia. PRyMordial is publicly available on GitHub. [ABSTRACT FROM AUTHOR]

This paper presents a measurement of the inclusive 3-jet production differential cross section at a proton-proton centre-of-mass energy of 7 TeV using data corresponding to an integrated luminosity of 5 $$\,\mathrm{fb}^{-1}$$ collected with the CMS detector. The analysis is based on the three jets with the highest transverse momenta. The cross section is measured as a function of the invariant mass of the three jets in a range of 445-3270 GeV and in two bins of the maximum rapidity of the jets up to a value of 2. A comparison between the measurement and the prediction from perturbative QCD at next-to-leading order is performed. Within uncertainties, data and theory are in agreement. The sensitivity of the observable to the strong coupling constant $$\alpha _\mathrm {S}$$ is studied. A fit to all data points with 3-jet masses larger than 664 GeV gives a value of the strong coupling constant of $$\alpha _S(M_\mathrm{Z}) = 0.1171 \pm 0.0013\,\text {(exp)} \,^{+0.0073}_{-0.0047}\,\text {(theo)} $$ . [ABSTRACT FROM AUTHOR]

Belle II recently reported the first measurement of B + → K + + inv , which is 2.8 σ above the Standard Model prediction. We explore the available parameter space of new physics within Standard Model effective field theory extended by sterile neutrinos (ν SMEFT) and provide predictions for the other B → K (⋆) + inv decay modes and invisible B s decays. We also briefly comment on charged current decays B → D (⋆) ℓ ν ¯ and possible ultraviolet completions of the relevant ν SMEFT operators. [ABSTRACT FROM AUTHOR]

The yield of muon pairs in the invariant mass region 1< M<2.5 GeV/ c2 produced in heavy-ion collisions significantly exceeds the sum of the two expected contributions, Drell-Yan dimuons and muon pairs from the decays of D meson pairs. These sources properly account for the dimuons produced in proton-nucleus collisions. In this paper, we show that dimuons are also produced in excess in 158 A GeV In-In collisions. We furthermore observe, by tagging the dimuon vertices, that this excess is not due to enhanced D meson production, but made of prompt muon pairs, as expected from a source of thermal dimuons specific to high-energy nucleus-nucleus collisions. The yield of this excess increases significantly from peripheral to central collisions, both with respect to the Drell-Yan yield and to the number of nucleons participating in the collisions. Furthermore, the transverse mass distributions of the excess dimuons are well described by an exponential function, with inverse slope values around 190 MeV. The values are independent of mass and significantly lower than those found at masses below 1 GeV/ c2, rising there up to 250 MeV due to radial flow. This suggests the emission source of thermal dimuons above 1 GeV/ c2 to be of largely partonic origin, when radial flow has not yet built up. [ABSTRACT FROM AUTHOR]

In this paper, we use a formalism including supersymmetry to calculate the Green function for the spinning relativistic particle in the presence of the step potential. This is an example of one of simple but fundamental inhomogeneous fields. We obtain an explicit expression of the Polyakov spin factor and the presence of the step gives rise to a correction of a delta potential in the spin–field coupling. The calculation is done using the perturbation technique. The corresponding positive- and negative-energy states are obtained. This Green function is used to evaluate a pair-creation probability in this potential. [ABSTRACT FROM AUTHOR]

In this paper we review the properties of the 1/Nf expansion in multi-dimensional theories. Contrary to the usual perturbative expansion it is renormalizable and contains only logarithmic divergencies. The price for it is the presence of ghost states, which, however, in certain cases do not contribute to physical amplitudes. In this case the theory is unitary and one can calculate the cross-sections. As an example we consider the differential cross-section of elastic eq→eq scattering in a D=7,11,...-dimensional world. We look also for the unification of the gauge couplings in the multi-dimensional standard model and its SUSY extension, which occurs at energies lower than in 4 dimensions. [ABSTRACT FROM AUTHOR]

This paper describes a topological search for an invisibly decaying Higgs boson, H, produced via the Bjorken process (e+e-→HZ). The analysis is based on data recorded using the OPAL detector at LEP at centre-of-mass energies from 183 to 209 GeV corresponding to a total integrated luminosity of 629 pb-1. In the analysis only hadronic decays of the Z boson are considered. A scan over Higgs boson masses from 1 to 120 GeV and decay widths from 1 to 3000 GeV revealed no indication for a signal in the data. From a likelihood ratio of expected signal and standard model background we determine upper limits on cross-section times branching ratio to an invisible final state. For moderate Higgs boson decay widths, these range from about 0.07 pb (MH=60 GeV) to 0.57 pb (MH=114 GeV). For decay widths above 200 GeV the upper limits are of the order of 0.15 pb. The results can be interpreted in general scenarios predicting a large invisible decay width of the Higgs boson. As an example we interpret the results in the so-called stealthy Higgs scenario. The limits from this analysis exclude a large part of the parameter range of this scenario experimentally accessible at LEP 2. [ABSTRACT FROM AUTHOR]

There is a remarkable connection between the number of quantum states of conformal theories and the sequence of dimensions of Lie algebras. In this paper, we explore this connection by computing the asymptotic expansion of the elliptic genus and the microscopic entropy of black holes associated with (supersymmetric) sigma models. The new features of these results are the appearance of correct prefactors in the state density expansion and in the coefficient of the logarithmic correction to the entropy. [ABSTRACT FROM AUTHOR]

In this paper, the principles of the general relativity are used to formulate quantum wave equations for spin-0 and spin-1/2 particles. More specifically, the equations are worked in a Schwarzschild like metric. As a test, the hydrogen atom spectrum is calculated. A comparison of the calculated spectrum with the numerical data of the deuterium energy levels shows a significant improvement of the accord, and the deviations are almost five times smaller then the ones obtained with the Dirac theory. The implications of the theory considering the strong interactions are also discussed. [ABSTRACT FROM AUTHOR]

We complete here our work on isospin violation in thesystem. We first calculateto the same order as we didin papers I and II of this series. This adds the effects of orderG27p2 (mu-md) andG27p2e2 to earlier work. We calculate also the lowest order bremsstrahlung contributions,. With these and our earlier results we perform a full fit to all availableCP-conserving data in thesystem including isospin violation effects. We perform these fits under various input assumptions as well as test the factorization and the vector dominance model for the weak NLO low energy constants. [ABSTRACT FROM AUTHOR]

Even if dark matter particles were unambiguously discovered in experiments, there is no clear reason to expect that this would resolve the dark matter problem. It is very easy to provide examples of dark matter scenarios (e.g. in supersymmetric models) in which nearly identical detector signals correspond to extremely different relic densities. The density of the discovered particles, therefore, must be determined before their cosmological relevance can be established. In this paper, I present a general method that utilizes both dark matter and hadron collider experimental data (once they become available) to estimate the local density of dark matter particles. These results were obtained in collaboration with Gordon Kane at the University of Michigan. [ABSTRACT FROM AUTHOR]

This paper introduces the Solenoidal Tracker experiment at the Relativistic Heavy Ion Collider. The corrected p T spectra and the yields of the $\Sigma (1385)^{\pm}$ and their antiparticles in the most central Au + Au and elementary p + p collisions are presented. Comparison of the $\Sigma (1385)$ $\langle p_{T} \rangle$ measurement with the other particles corroborates the fact that the $\langle p_{T} \rangle$ behavior for hyperons (mass> 1.2 GeV) is similar in p + p and Au + Au collisions. The $\Sigma (1385)/\Lambda$ ratio, along with other resonance-to-stable-particle ratios, suggests that a regeneration mechanism recovers the signal loss due to re-scattering in the final state in Au + Au collisions. [ABSTRACT FROM AUTHOR]

In this paper the revised Kajantie-Byckling approach and improved phase space sampling techniques for the massive multi-particle final states are presented. The application of the developed procedures to the processes representative for LHC physics indicates the possibility of a substantial simplification of multi-particle phase space sampling while retaining a respectable weight variance reduction and unweighing efficiencies in the event generation process. [ABSTRACT FROM AUTHOR]

We examine the soft supersymmetry breaking parameters in supersymmetric theories on a slice of AdS5 which generate the hierarchical Yukawa couplings by dynamically quasi-localizing the bulk matter fields in an extra dimension. Such models can be regarded as the AdS dual of the recently studied 4-dimensional models which contain a supersymmetric CFT to generate the hierarchical Yukawa couplings. In such models, if supersymmetry breaking is mediated by the bulk radion superfield and/or some brane chiral superfields, potentially dangerous flavor-violating soft parameters are suppressed with an appropriate correlation with the Yukawa coupling suppression, thereby avoiding the SUSY flavor problem in a natural manner. We present some models of radion-dominated supersymmetry breaking which yield a highly predictive form of soft parameters in this framework, and discuss the constraints from flavor-changing rare processes. Most of the discussions in this paper can be applied also to models with a flat extra dimension in which the Yukawa hierarchy is generated by quasi-localizing the bulk matter fields in the extra dimension. [ABSTRACT FROM AUTHOR]

Approximately 438 pb-1 of e+e- data from the OPAL detector, taken with the LEP collider running at centre-of-mass energies of 192-209 GeV, are analyzed to search for evidence of chargino pair production, e+e- → &χmacr;1+&χmacr;1-, or neutralino associated production, e+e- → &χmacr;20&χmacr;10. Limits are set at the 95% confidence level on the product of the cross-section for the process e+e- → &χmacr;1+&χmacr;1- and its branching ratios to topologies containing jets and missing energy, or jets with a lepton and missing energy, and on the product of the cross-section for e+e- → &χmacr;20&χmacr;10 and its branching ratio to jets. R-parity conservation is assumed throughout this paper. When these results are interpreted in the context of the Constrained Minimal Supersymmetric Standard Model, limits are also set on the masses of the &χmacr;1±, &χmacr;10 and &χmacr;20, and regions of the parameter space of the model are ruled out. Nearly model-independent limits are also set at the 95% confidence level on a(e+e- → &χmacr;1+ &χmacr;1-) with the assumption that each chargino decays via a W boson, and on σ(e+e- → &χmacr;20&χmacr;10 with the &χmacr;20 assumed to decay via a Z0. [ABSTRACT FROM AUTHOR]

Oscillations in the Bs0-&Bs0macr; system were studied in events selected from about 4.3 million hadronic Z0 decays registered by DELPHI between 1992 and 2000. This paper presents updates of two published analyses ([11,12]). The first analysis, which utilizes leptons emitted with large momentum transverse to a jet, was improved by means of a better algorithm for the vertex reconstruction and a new algorithm for flavour-tagging at production time. The second analysis, which utilizes Ds-lepton events, was improved by optimizing the treatment of proper time resolution. No signal of Bs0 oscillations was observed and limits on the mass difference between the physical Bs0 states were obtained to be: Δms > 8.0 ps-1 at the 95% C.L. with a sensitivity of Δms = 9.1 ps-1 in the high pt lepton analysis and Δms > 4.9 ps-1 at the 95% C.L. with a sensitivity of Δms = 8.6 ps-1 in the Ds-lepton analysis. Previously published results on these analyses are superseded. The combination of these results with those obtained in other independent analyses previously performed in DELPHI (Ds-hadron, exclusive Bs0, inclusive vertex) gives: Δms > 8.5 ps-1 at the 95% C.L. with a sensitivity of Δms = 12.0 ps-1. [ABSTRACT FROM AUTHOR]

The CMS experiment will take data at the CERN LHC starting from 2007. The CMS muon system has been designed to identify, reconstruct and measure muons with high efficiency and accuracy. In this paper the layout of the system and the key features of the detectors are presented. The reconstruction algorithms, in the context of the High Level Trigger, and their performance in terms of resolution, rate reduction and trigger efficiency are also discussed. PACS: 25.70.Ef – 21.60.Gx – 27.30.+t [ABSTRACT FROM AUTHOR]

TOTEM will measure the total pp cross-section at LHC by using a luminosity independent method based on simultaneous evaluation of the total elastic and inelastic rates. For an extended coverage of the inelastic and diffractive events, two forward tracking telescope are employed. The elastically or diffractively scattered protons are measured by a set of special detectors, which can be moved close to the circulating protons beams. The paper describes the physics reach of the experiment and the detectors which are being considered. PACS: 25.70.Ef – 21.60.Gx – 27.30.+t [ABSTRACT FROM AUTHOR]

The CMS trigger system must reduce an input data rate from the LHC bunch-crossing frequency of 40 MHz to a rate which will be written to permanent storage. A detailed study has recently been made of the performance of this system. This paper presents key elements of the results obtained and gives details of a draft “trigger table” for the Level-1 Trigger and the High-Level Trigger selection at a “start-up” luminosity of 2× 1033 cm – 2s – 1. High efficiencies for most physics objects are attainable with a selection that remains inclusive and avoids detailed topological or other requirements on the event. [ABSTRACT FROM AUTHOR]

The standard method used for tagging b-hadrons in the DELPHI experiment at the CERN LEP Collider is discussed in detail. The main ingredient of b-tagging is the impact parameters of tracks, which relies mostly on the vertex detector. Additional information, such as the mass of particles associated to a secondary vertex, significantly improves the selection efficiency and the background suppression. The paper describes various discriminating variables used for the tagging and the procedure of their combination. In addition, applications of b-tagging to some physics analyses, which depend crucially on the performance and reliability of b-tagging, are described briefly. [ABSTRACT FROM AUTHOR]

This paper summazises the search for the Standard Model Higgs boson in e+e- collisions at centre-of-mass energies up to 209 GeV performed by the OPAL Collaboration at LEP. The consistency of the data with the background hypothesis and various Higgs boson mass hypotheses is examined. No indication of a signal is found in the data and a lower bound of 112.7 GeV/c² is obtained on the mass of the Standard Model Higgs boson at the 95% CL. [ABSTRACT FROM AUTHOR]

Several new physics scenarios that address anomalies in B-physics predict an enhancement of b → s τ τ with respect to its Standard Model prediction. Such scenarios necessarily imply modifications of the lifetime ratio τ B s / τ B d and the lifetime difference Δ Γ s . In this work, we explore indirect bounds provided by these observables over new physics scenarios. We also estimate future projections, showing that future experimental and theoretical improvements on both τ B s / τ B d and Δ Γ s have the potential to provide bounds competitive with those directly extracted from b → s τ τ transitions. After performing a model-independent analysis, we apply our results to the particular case of leptoquark mediators proposed to address the R D (∗) anomalies. [ABSTRACT FROM AUTHOR]