Search

We recall a resummation procedure in QED to extract the zero momentum mode in soft photon emission and present an ansatz about a possible mechanism for the forward peak characterizing elastic proton proton scattering., Comment: 8 pages, 4 figures

In the present investigation the glass forming ability of Ce65Al25Co10 metallic glass has been reported. It was successfully synthesised using melt spinning techniques. The existence of amorphous phase in Ce65Al25Co10 alloy have been proved using X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The thermal analysis of the synthesised sample using differential scanning calorimetry (DSC) shows a glass transition around 371 K, thus confirms existence of glassy phase at room temperature. The hardness of the synthesised sample at different load have been demonstrated. Moreover, the yield strength of the synthesised sample has also been calculated by means of hardness data and Meyer exponent., Comment: 16 pages, 6 figures

The present study reports on the structural and magnetic phase transitions in Pr-doped polycrystalline Tb0.6Pr0.4MnO3, using high-resolution neutron powder diffraction (NPD) collected at SINQ spallation source (PSI), to emphasize the suppression of the sinusoidal magnetic structure of pure TbMnO3 and the evolution to a collinear A-type antiferromagnetic ordering. The phase purity, Jahn-Teller distortion, and one-electron bandwidth for eg orbital of Mn3+ cation have been calculated for polycrystalline Tb0.6Pr0.4MnO3, in comparison to the parent materials TbMnO3 and PrMnO3, through the Rietveld refinement study from X-ray diffraction data at room temperature. The temperature-dependent zero field-cooled and field-cooled dc magnetization study at low temperature down to 5 K reveals a variation in the magnetic phase transition due to the effect of Pr3+ substitution at the Tb3+ site, which gives the signature of the antiferromagnetic nature of the sample, with a weak ferromagnetic component at low temperature induced by an external magnetic field. The field-dependent magnetization study at low temperatures gives the weak coercivity having the order of 2 kOe, which is expected due to canted-spin arrangement or ferromagnetic nature of Terbium ordering. The NPD data for Tb0.6Pr0.4MnO3 confirms that the nuclear structure of the synthesized sample maintains its orthorhombic symmetry down to 1.5 K. Also, the magnetic structures have been solved at 50 K, 25 K, and 1.5 K through the NPD study, which shows A-type antiferromagnetic spin arrangement., Comment: 21 Pages, 8 Figures, 7 Tables

The first time one of us (G.P.) encountered Earle was in Summer 1966, when she was directed to study Earle's papers on radiative corrections to quasi-elastic electron scattering. The suggestion had come from Bruno Touschek, at the time head of the theoretical physics group at the Frascati National Laboratories near Rome. About the same time, Earle came from MIT to visit University of Rome and Frascati. G.P. was a young post-graduate, who had studied Earle's papers and was awed by his already impressive scientific figure. After almost 40 years had passed, Earle visited Italy with his wife Ruth, making Frascati their base for an extended visit of almost a month. They were housed in what was then the laboratory hostel for foreign visitors, a small villa higher up above the hill, toward the town of Frascati. Since then, we became close friends, a friendship which included both his family and ours, and which has been very important for us. In memory of that first visit and in gratitude for the many years of friendship, we will tell here a story of infrared radiative corrections to charged particle scattering, to which Earle's papers gave an important contribution., Comment: A contribution to Earle Lomon's 90th birthday celebration, 8 pages

We examine present data for double parton scattering at LHC and discuss their energy dependence from its earliest measurements at the ISR. Different models for the effective cross-section are considered and their behavior studied for a variety of selected final states. We point out that data for pp ->4 jets or pp -> quarkonium pair indicate the effective cross-section to increase with energy. We compare this set of data with different models, including one inspired by our soft gluon resummation model for the impact parameter distribution of partons., Comment: 8 pages, 2 figures, to appear in the Proceedings for LFC19: Strong dynamics for physics within and beyond the Standard Model at LHC and Future Colliders, Frascati Physics Series Vol. 69 (2019)

An earlier forward and backward in time formalism developed by us to discuss non-relativistic electron diffraction is generalized to the relativistic case and here applied to photons. We show how naturally the zero-point energy emerges in the Planck black-body spectrum once symmetric in time motion - inherent in the Maxwell equations - is invoked for photons. Then, a detailed study is made of two-slit experiments for photons and some novel phenomena, amenable to experiments, are proposed, that arise due to the spin of the photon., Comment: 10 pages. arXiv admin note: text overlap with arXiv:1510.06272

We report the exotic photoluminescence (PL) behaviour of 3D topological insulator Bi2Te3 single crystals grown by customized self-flux method and mechanically exfoliated few layers (18 plus minus 2 nm)/thin flakes obtained by standard scotch tape method from as grown Bi2Te3 crystals.The experimental PL studies on bulk single crystal and mechanically exfoliated few layers of Bi2Te3 evidenced a broad red emission in the visible region. These findings are in good agreement with our theoretical results obtained using the ab initio density functional theory framework., Comment: Main MS (17 Pages text including 4 Figs): Suppl. info. (4 pages); Accepted Scientific Reports

We discuss a model for soft gluon re-summation based on a statistical description of independent emissions during inelastic collisions. The model is applied to estimate Survival Probabilities at the LHC. A comparison with other models and experimental data is presented., Comment: 6 pages, 6 figures, to appear in the Proceedings of LFC17: Old and New Strong Interactions from LHC to Future Colliders, ECT*, Trento, 11-15 September 2017

We update our previous search for trapped magnetic monopoles in LHC Run 2 using nearly six times more integrated luminosity and including additional models for the interpretation of the data. The MoEDAL forward trapping detector, comprising 222~kg of aluminium samples, was exposed to 2.11~fb$^{-1}$ of 13 TeV proton-proton collisions near the LHCb interaction point and analysed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges equal to the Dirac charge or above are excluded in all samples. The results are interpreted in Drell-Yan production models for monopoles with spins 0, 1/2 and 1: in addition to standard point-like couplings, we also consider couplings with momentum-dependent form factors. The search provides the best current laboratory constraints for monopoles with magnetic charges ranging from two to five times the Dirac charge., Comment: 8 pages, 5 figures, 1 table, accepted for publication in Phys. Lett. B

We present an estimate of survival probability from an eikonal mini- jet model implemented with a proposal for soft gluon resummation to all orders. We compare it with experimental data for diffractive di-jet production from LHC experiments, CMS and ATLAS, both at LO and NLO order., Comment: 6 pages, 2 figures, Presented at EDS Blois 2017, Prague, Czech Republic, June 26-30, 2017

Recent results for the total and inelastic hadronic cross-sections from LHC experiments are compared with predictions from a single channel PDF driven eikonal mini-jet model and from an empirical model. The role of soft gluon resummation in the infrared region in taming the rise of mini-jets and their contribution to the increase of the total cross-sections at high energies are discussed. Survival probabilities at LHC, whose theoretical estimates range from circa 10 percent to a few per mille, will be estimated in this model and compared with results from QCD inspired models and from multi channel eikonal models. We revisit a previous calculation and examine the origin of these discrepancies., Comment: 30 pages in single column, 6 figures

We consider the production at the LHC of exotic composite quarks of charge $Q=+(5/3) e$ and $Q=-(4/3) e$. Such states are predicted in composite models of higher isospin multiplets ($I_W=1$ or $I_W=3/2$). Given their exotic charges (such as $5/3$), their decays proceed through the electroweak interactions. We compute decay widths and rates for resonant production of the exotic quarks at the LHC. Partly motivated by the recent observation of an excess by the CMS collaboration in the $e\not p_T jj$ final state signature we focus on $ pp \to U^+ j \to W^+ + j\, j\, \to \ell^+\not p_T jj$ and then perform a fast simulation of the detector reconstruction based on DELPHES. We then scan the parameter space of the model ($m_*=\Lambda$) and study the statistical significance of the signal against the relevant standard model background ($Wjj$ followed by leptonic decay of the $W$ gauge boson) providing the luminosity curves as function of $m_*$ for discovery at 3- and 5-$\sigma$ level., Comment: 14 pages, 10 figures