Lepton flavour violating decay of 125 GeV Higgs boson to μτ\mu\tau channel and excess in ttˉHt\bar t H

A recent search for the lepton flavor violating (LFV) decays of the Higgs boson, performed by CMS collaboration, reports an interesting deviation from the standard model (SM). The search conducted in the channel $H\rightarrow \mu\tau_e$ and $H\rightarrow \mu\tau_{\textrm{had}}$ shows an excess of $2.4\sigma$ signal events with 19.7 fb$^{-1}$ data at a center-of-mass energy $\sqrt s=8$ TeV. On the other hand, a search performed by CMS collaboration for the SM Higgs boson produced in association with a top quark pair ($t\bar t H$) also showed an excess in the same-sign di-muon final state. In this work we try to find out if these two seemingly uncorrelated excesses are related or not. Our analysis reveals that a lepton flavour violating Higgs decay ($H\rightarrow\mu\tau$) can partially explain the excess in the same sign di-muon final state in the $t\bar t H$ search, infact brings down the excess well within 2$\sigma$ error of the SM expectation. Probing such non-standard Higgs boson decay is of interest and might contain hints of new physics at the electroweak scale.Comment: 10 pages, 2 figures and 3 table

Study of energy deposition patterns in hadron calorimeter for prompt and displaced jets using convolutional neural network

Sophisticated machine learning techniques have promising potential in search for physics beyond Standard Model in Large Hadron Collider (LHC). Convolutional neural networks (CNN) can provide powerful tools for differentiating between patterns of calorimeter energy deposits by prompt particles of Standard Model and long-lived particles predicted in various models beyond the Standard Model. We demonstrate the usefulness of CNN by using a couple of physics examples from well motivated BSM scenarios predicting long-lived particles giving rise to displaced jets. Our work suggests that modern machine-learning techniques have potential to discriminate between energy deposition patterns of prompt and long-lived particles, and thus, they can be useful tools in such searches.Comment: 32 pages, 17 figures; version accepted for publication in JHE

A docking interaction study of the effect of critical mutations in ribonuclease a on protein-ligand binding

Enzymes with ribonucleolytic activity play a pivotal role in gene expression and cellular homeostasis by altering the levels of cellular RNA. Ribonuclease A has been the most well studied of such enzymes whose histidine residues (His12 and His119) play a crucial role in the catalytic mechanism of the protein. The ligands chosen for this study, 2′CMP and 3′CMP, act as competitive substrate analog inhibitors of this enzyme. Using molecular graphics software freely available for academic use, AutoDock and PyMol, we demonstrate that substitution of either histidine residue by alanine causes marked changes in the distances between these critical residues of the enzyme. The ligands in the docked conformation (particularly on mutation of His119 to Ala) compensate for the altered free energy and hydrogen bonding abilities in these new protein‐ligand complexes

HiSE: Hierarchical (Threshold) Symmetric-key Encryption

Threshold symmetric encryption (TSE), introduced by Agrawal et al. [DiSE, CCS 2018], provides scalable and decentralized solution for symmetric encryption by ensuring that the secret-key stays distributed at all times. They avoid having a single point of attack or failure, while achieving the necessary security requirements. TSE was further improved by Christodorescu et al. [ATSE, CCS 2021] to support an amortization feature which enables a “more privileged” client to encrypt records in bulk by interacting only once with the key servers, while decryption must be performed individually for each record, potentially by a “less privileged” client. However, typical enterprises collect or generate data once and query it several times over its lifecycle in various data processing pipelines; i.e., enterprise workloads are often decryption heavy! ATSE does not meet the bar for this setting because of linear interaction / computation (in the number of records to be decrypted) – our experiments show that ATSE provides a sub-par throughput of a few hundred records / sec. We observe that a large class of queries read a subsequence of records (e.g. a time window) from the database. With this access structure in mind, we build a new TSE scheme which allows for both encryption and decryption with flexible granularity, in that a client’s interactions with the key servers is at most logarithmic in the number of records. Our idea is to employ a binary-tree access structure over the data, where only one interaction is needed to decrypt all ciphertexts within a sub-tree, and thus only log-many for any arbitrary size sub-sequence. Our scheme incorporates ideas from binary-tree encryption by Canetti et al. [Eurocrypt 2003] and its variants, and carefully merges that with Merkle-tree commitments to fit into the TSE setting. We formalize this notion as hierarchical threshold symmetric-key encryption (HiSE), and argue that our construction satisfies all essential TSE properties, such as correctness, privacy and authenticity with respect to our definition. Our analysis relies on a well-known XDH assumption and a new assumption, that we call $\ell$-masked BDDH, over asymmetric bilinear pairing in the programmable random oracle model. We also show that our new assumption does hold in generic group model. We provide an open-source implementation of HiSE. For practical parameters, we see 65$\times$ improvement in latency and throughput over ATSE. HiSE can decrypt over 6K records / sec on server-grade hardware, but the logarithmic overhead in HiSE’s encryption (not decryption) only lets us encrypt up to 3K records / sec (about 3-4.5$\times$ slowdown) and incurs roughly 500 bytes of ciphertext expansion per record – while reducing this penalty is an important future work, we believe HiSE can offer an acceptable tradeoff in practice

A comparative study of interaction of tetracycline with several proteins using time resolved anisotropy, phosphorescence, docking and FRET

A comparative study of the interaction of an antibiotic Tetracycline hydrochloride (TC) with two albumins, Human serum albumin (HSA) and Bovine serum albumin (BSA) along with Escherichia Coli Alkaline Phosphatase (AP) has been presented exploiting the enhanced emission and anisotropy of the bound drug. The association constant at 298 K is found to be two orders of magnitude lower in BSA/HSA compared to that in AP with number of binding site being one in each case. Fluorescence resonance energy transfer (FRET) and molecular docking studies have been employed for the systems containing HSA and BSA to find out the particular tryptophan (Trp) residue and the other residues in the proteins involved in the binding process. Rotational correlation time (θc) of the bound TC obtained from time resolved anisotropy of TC in all the protein-TC complexes has been compared to understand the binding mechanism. Low temperature (77 K) phosphorescence (LTP) spectra of Trp residues in the free proteins (HSA/BSA) and in the complexes of HSA/BSA have been used to specify the role of Trp residues in FRET and in the binding process. The results have been compared with those obtained for the complex of AP with TC. The photophysical behaviour (viz., emission maximum, quantum yield, lifetime and θc) of TC in various protic and aprotic polar solvents has been determined to address the nature of the microenvironment of TC in the protein-drug complexes

Universally Composable Non-Interactive Zero-Knowledge from Sigma Protocols via a New Straight-line Compiler

Non-interactive zero-knowledge proofs (NIZK) are essential building blocks in threshold cryptosystems like multiparty signatures, distributed key generation, and verifiable secret sharing, allowing parties to prove correct behavior without revealing secrets. Furthermore, universally composable (UC) NIZKs enable seamless composition in the larger cryptosystems. A popular way to construct NIZKs is to compile interactive protocols using the Fiat-Shamir transform. Unfortunately, Fiat-Shamir transformed NIZK requires rewinding the adversary and is not $\textit{straight-line extractable}$, making it at odds with UC. Using Fischlin\u27s transform gives straight-line extractability, but at the expense of many repetitions of the underlying protocol leading to poor concrete efficiency and difficulty in setting parameters. In this work, we propose a simple new transform that compiles a Sigma protocol for an algebraic relation into a UC-NIZK protocol $\textit{without any overheads of repetition}$. - Given a Sigma protocol for proving m algebraic statements over n witnesses, we construct a compiler to transform it into a $\textit{straight-line extractable}$ protocol using an additively homomorphic encryption scheme AHE. Our prover executes the Sigma protocol\u27s prover once and computes 2n encryptions. The verification process involves running the Sigma protocol verifier once and then computing n encryptions, which are homomorphically verified against the prover generated encryptions. - We apply the Fiat-Shamir transform to the above straight-line extractable Sigma protocol to obtain a UC-NIZK. We instantiate AHE using class group-based encryption where the public key of the encryption scheme is obliviously sampled using a suitable hash function. This yields a UC-NIZK protocol in the random oracle model

New physics searches with heavy-ion collisions at the CERN Large Hadron Collider

This document summarises proposed searches for new physics accessible in the heavy-ion mode at the CERN Large Hadron Collider (LHC), both through hadronic and ultraperipheral gamma gamma interactions, and that have a competitive or, even, unique discovery potential compared to standard proton-proton collision studies. Illustrative examples include searches for new particles-such as axion-like pseudoscalars, radions, magnetic monopoles, new long-lived particles, dark photons, and sexaquarks as dark matter candidates-as well as new interactions, such as nonlinear or non-commutative QED extensions. We argue that such interesting possibilities constitute a well-justified scientific motivation, complementing standard quark-gluon-plasma physics studies, to continue running with ions at the LHC after the Run-4, i.e. beyond 2030, including light and intermediate-mass ion species, accumulating nucleon-nucleon integrated luminosities in the accessible fb(-1) range per month.Peer reviewe