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Novel signature for long-lived particles at the LHC
No full textIn contrast to the decay products ensuing from a fast moving particle which are collimated along the original direction of the parent, those from a slow moving particle are distributed over a wide region. In the context of searches for heavy long-lived particles (LLP) at the Large Hadron Collider (LHC), we quantitatively demonstrate, using a few benchmark models, that objects which emerge from a secondary vertex due to the decay of a LLP at the TeV scale can be at large angular separations with respect to the direction of the parent LLP. A fraction of the decay products, the backward moving objects (BMOs), can even go in the backward direction. These give rise to striking signatures in the detectors at the LHC as these particles traverse different layers of the detector outside-in towards the direction of the beam pipe. Based on a simple geometrical modeling of the detector, we give examples of how this effect translates into the fraction of energy deposited in the tracker, from particles coming as far as from the hadron calorimeter, as well as those that could be entering from outside the detector into the muon chamber. The largest effect is from LLP candidates that come to rest inside the detector, such as the stopped R-hadrons. But the results are promising even in the case of not so heavy LLPs and/or when some of the available energy is carried by a massive invisible daughter. This urges us to look more in detail at these unusual signatures, taking into account the particularities of each layer that constitutes the detector. From the BMO perspective, we review how each layer of the detector could be exploited and what improvements can be made to enhance the shower shapes and the timing information, for instance. We also argue that the cosmic ray events, the most important background, can be easily dealt with
Energy Efficient Secure Communication in Wireless Sensor Networks
No full textA Wireless Sensor Network (WSN) consists of sensor nodes which communicate with each other using wireless only, and it is usually deployed over inaccessible regions to collect information from the environment. Today WSNs have many applications, but sensor nodes of WSNs are resource constraint devices, in particular, energy constraint devices. Hence, it is required to minimize the energy consumption of sensor nodes as far as possible. Security in WSNs is also an important requirement since WSNs cannot meet their objectives without having security. Besides, solutions to security problems in WSNs have to meet not only the security goals of WSNs but also consume as minimum energy as possible. Both symmetric key cryptography and public key cryptography have been used to provide solutions to security problems in WSNs. Public key cryptography consumes more energy compared to symmetric key cryptography, but public key cryptography can provide unique identity to each sensor node besides fulfilling other security requirements. In contrast, symmetric key cryptography like encryption and MAC computation is vulnerable to cryptanalysis, and therefore, keys need to be renewed frequently. In this paper, we propose a scheme for energy efficient secure communication between pairs of sensor nodes essentially using symmetric key cryptography ensuring authenticity and integrity of messages. We have used ECC-based public key cryptography only to identify each node uniquely, and to establish initial symmetric keys between pairs of sensor nodes. In the proposed scheme, we make use of a key generation technique to reduce the frequency of key renewals and symmetric key-based Diffie-Hellman key renewal scheme to reduce the energy consumed during key renewals. The proposed scheme has been compared with basic secure communication scheme which uses ECC-based public key cryptography for key renewal. We have carried out the simulation study of the proposed scheme using Cooja simulator for Contiki 3.x operating system, and the simulation results show that the proposed scheme consumes less energy than the basic secure communication scheme
Measurements of the differential jet cross section as a function of the jet mass in dijet events from proton -proton collisions at=13 TeV
No full textMeasurements of the differential jet cross section are presented as a function of the jet mass in dijet events, in bins of jet transverse momentum, with and without a jet grooming algorithm. The data have been recorded by the CMS Collaboration in proton-proton collisions at the LHC at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 2.3 fb(-1). The absolute cross sections show slightly different jet transverse momentum spectra in data and Monte Carlo event generators for the settings used. Removing this transverse momentum dependence, the normalized cross section for ungroomed jets is consistent with the prediction from Monte Carlo event generators for masses below 30% of the transverse momentum. The normalized cross section for groomed jets is measured with higher precision than the ungroomed cross section. Semi-analytical calculations of the jet mass beyond leading logarithmic accuracy are compared to data, as well as predictions at leading order and next-to-leading order, which include parton showering and hadronization. Overall, in the normalized cross section, the theoretical predictions agree with the measured cross sections within the uncertainties for masses from 10 to 30% of the jet transverse momentum
Search for the decay of a Higgs boson in the ℓℓγ channel in proton-proton collisions at s√=13 TeV
No full textA search for a Higgs boson decaying into a pair of electrons or muons and a photon is described. Higgs boson decays to a Z boson and a photon (H Z , = e or ), or to two photons, one of which has an internal conversion into a muon pair (H (*) ) were considered. The analysis is performed using a data set recorded by the CMS experiment at the LHC from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). No significant excess above the background prediction has been found. Limits are set on the cross section for a standard model Higgs boson decaying to opposite-sign electron or muon pairs and a photon. The observed limits on cross section times the corresponding branching fractions vary between 1.4 and 4.0 (6.1 and 11.4) times the standard model cross section for H (*) (H Z ) in the 120-130 GeV mass range of the system. The H (*) and H Z analyses are combined for m(H) =125GeV, obtaining an observed (expected) 95% confidence level upper limit of 3.9 (2.0) times the standard model cross section
Search for a massive resonance decaying to a pair of Higgs bosons in the four b quark final state in proton-proton collisions at root s=13 TeV
No full textA search for a massive resonance decaying into a pair of standard model Higgs bosons, in a final state consisting of two b quark-antiquark pairs, is performed. A data sample of proton-proton collisions at a centre-of-mass energy of 13 TeV is used, collected by the CMS experiment at the CERN LHC in 2016, and corresponding to an integrated luminosity of 35.9 fb(-1). The Higgs bosons are highly Lorentz-boosted and are each reconstructed as a single large-area jet. The signal is characterized by a peak in the dijet invariant mass distribution, above a background from the standard model multijet production. The observations are consistent with the background expectations, and are interpreted as upper limits on the products of the s-channel production cross sections and branching fractions of narrow bulk gravitons and radions in warped extra-dimensional models. The limits range from 126 to 1.4 fb at 95% confidence level for resonances with masses between 750 and 3000 GeV, and are the most stringent to date, over the explored mass range. (C) 2018 The Author(s). Published by Elsevier B.V
Neuromorphic Object Tracking Architecture, Based on Compound Eyes, and Implementation on FPGA
No full textRecent findings in neuroscience, show that rapid changes in flight direction of a housefly/blowfly (mainly to track objects) are attributable to neural circuits distributed behind its photo-receptors. While tracking objects, using its compound eye structure, a fly is able to detect changes in the motion of the object quickly and changes its own motion accordingly. The working of these neural circuits may be modelled as a set of leaky integrate and fire neurons connected in a special manner to form a competitive feedback control. Based on this knowledge, we present a neuromorphic competitive control circuit utilizing an inference neuron model to control N actuators and analyze their outputs for tracking an object. This model was simulated in software first and then implemented on a Xilinx Artix-7 XC7A35T- ICPG236C FPGA board using Verilog. The results show an observable decoherence phenomenon between the neurons and support the working principle of the model
A unified decision making framework for supply and demand management in microgrid networks
No full textThis paper considers two important problems- on the supply-side and demand-side respectively and studies both in a unified framework. On the supply side, we study the problem of energy sharing among microgrids with the goal of maximizing profit obtained from selling power while at the same time not deviating much from the customer demand. On the other hand, under shortage of power, this problem becomes one of deciding the amount of power to be bought with dynamically varying prices. On the demand side, we consider the problem of optimally scheduling the time-adjustable demand - i.e., of loads with flexible time windows in which they can be scheduled. While previous works have treated these two problems in isolation, we combine these problems together and provide a unified Markov decision process (MDP) framework for these problems. We then apply the Q-learning algorithm, a popular model-free reinforcement learning technique, to obtain the optimal policy. Through simulations, we show that the policy obtained by solving our MDP model provides more profit to the microgrids
A Rate-Optimal Construction of Codes with Sequential Recovery with Low Block Length
No full textAn erasure code is said to be a code with sequential recovery with parameters r and t, if for any s <= t erased code symbols, there is an s-step recovery process in which at each step we recover exactly one erased code symbol by contacting at most r other code symbols. In this paper, we give a construction of binary codes with sequential recovery that are rate-optimal for any value of t and any value r >= 3. Our construction is based on construction of certain kind of tree-like graphs with girth t + 1. We construct these graphs and hence the codes recursively
Infrared Spectral Assignment of Pyrimidine and Pyrazine in the C-H Stretching Region by an Effective Spectroscopic Hamiltonian (vol 99, pg 196, 2018)
No full textMid-Infrared spectra of pyrimidine (PM) and pyrazine (PZ) were recorded in the gas phase using a multi-pass long path gas cell. The IR band structure of these compounds above and below 3000 cm−1 is very broad and contains many humps and shoulders. These humps and shoulders are due to various higher quantum excitation of low-frequency vibrational modes, which participate in Fermi resonance with the nearby CH stretch fundamentals and appears in this region. We constructed an Effective Spectroscopic Hamiltonian (ESH) in a mixed local mode (LM) normal mode (NM) basis to assign the various overtone and combination bands in the CH stretching region of these compounds. The CH stretching vibrations of both PZ and PM were treated as symmetrized anharmonic Morse oscillators in local coordinates and the in-plane deformations down to 1000 cm−1 were treated as normal coordinates. The ESHs were diagonalized and the resulting eigenvalues were subsequently fitted in a given parameter space with the experimentally observed bands. The eigenvalues of the converged Hamiltonian are the anharmonic frequencies and the transition intensities were obtained by summing the squared eigenvector components. The overtone and combination transitions near 3000 cm−1 of both PM and PZ were identified and assigned from the eigenvector coefficients of the ESH matrix. The wavefunctions of a pure CH stretch, overtone of the HCC in-plane bend and due to Type 1 Fermi coupling (resonance between a fundamental with an overtones of a low frequency mode, in this case resonance between the CH strech and the overtone of HCC in-plane bending modes) has been demonstrated pictorially
