arXiv subjects

S. Sahoo

Publications and source records attributed to S. Sahoo.

50 records · Page 3Linked to original sources

arXiv2013

The effect of z^prime boson on same-sign dimuon charge asymmetry in $ b_q^0 - bar b_q^0$ system

The recent observation of the same-sign dimuon charge asymmetry in the B system by the D0 collaboration has 3.9 sigma deviation from the standard model prediction. However, the recent LHCb data on B-s neutral-meson mixing do not accommodate the D0 collaboration result. In this paper, considering the effect of Z'-mediated flavour-changing neutral currents in the $ B_q^0 - bar B_q^0$ (q = d, s) mixing, the same-sign dimuon charge asymmetry is calculated. We find the same-sign dimuon charge asymmetry is enhanced from its SM prediction and provides signals for new physics beyond the SM

hep-ph↗

arXiv2013

Effect of both Z and Z^prime - mediated flavor-changing neutral currents on $B_s$ decays into $tau^+tau^-$

In recent years, $B_s$ decays into $tau^+tau^-$ has attracted a lot of attention since it is very sensitive to the structure of standard model (SM) and potential source of new physics beyond SM. In this paper, we study the effect of both Z and -mediated flavor-changing neutral currents on the $B_s$ decays into $tau^+tau^-$. We find the branching ratio of $B_s$ decays into $tau^+tau^-$ is enhanced relative to SM prediction, which would help to explain the recent observed CP-violation from like-sign dimuon charge asymmetry in the B system.

hep-ph↗

arXiv2012

Unification after 150 years

In 1861, James Clerk Maxwell unified electricity, magnetism and light. Today physicists are trying to unify everthing else theoretically as well as experimentally with a view to develop a fundamental theory.

physics.gen-ph↗

arXiv2012

String theory: big problem for small size

String theory is the most promising candidate theory for a unified description of all fundamental forces exist in the nature. It provides a mathematical framework that combine quantum theory with Einstein's general theory of relativity. But due to the extremely small size of strings, nobody has been able to detect it directly in the laboratory till today. In this article, we have presented a general introduction to string theory.

physics.gen-ph↗

arXiv2012

Time interval and lattice vibration in Raman effect, photoelectric effect and plane mirror reflection

Time interval between the incident and scattered photon in Raman effect and absorption of photon and emission of electron in photoelectric effect has not been determined till now. This is because there is no such high level instrument discovered till now to detect time interval to such a small level. But this can be calculated theoretically by applying a basic principle of physics like impulse is equal to the change in momentum. Considering the collision between electron and photon as perfect inelastic collision in photoelectric effect, elastic and inelastic collision in Raman effect and elastic collision in plane mirror reflection and the interaction between electron and photon as strong gravitational interaction we calculate the required time interval. During these phenomena there is lattice vibration which can be quantized as phonon particles.

physics.atom-ph↗

arXiv2011

Effect of both Z and Z'-mediated flavor-changing neutral currents on the baryonic rare decay $lambda_b$ decays into $lambda l^+l^- $

We study the effect of both Z and Z'-mediated flavor-changing neutral currents (FCNCs) on the $ lambda_b arrow lambda l^+l^- (l = mu, tau) $ rare decay. We find the branching ratio is reasonably enhanced from its standard model value due to the effect of both Z and Z'-mediated FCNCs, and gives the possibility of new physics beyond the standard model. The contribution of Z'-boson depends upon the precise value of the mass of Z' boson.

hep-ph↗

arXiv2011

Effect of Z'-mediated flavor-changing neutral current on B decays into Pi Pi

We study the effect of -mediated flavor-changing neutral current on the decays. The branching ratios of these decays can be enhanced remarkably in the non-universal model. Our estimated branching ratios are enhanced significantly from their standard model (SM) value. For = 1, the branching ratios are very close to the recently observed experimental values and for higher values of branching ratios are more. Our calculated branching ratios and are also enhanced from the SM value as well as the recently observed experimental values. These enhancements of branching ratios from their SM value give the possibility of new physics.

hep-ph↗

arXiv2011

The Prediction of Mass of Z'-Boson from $b_q^0-b_q^0 bar$ Mixing

$B_q^0-B_^0 bar$ mixing offers a profound probe into the effects of new physics beyond the Standard Model. In this paper, $B_s^0-B_s^0 bar$ and $B_d^0-B_d^0 bar$ mass differences are considered taking the effect of both Z-and Z' -mediated flavour-changing neutral currents in the $B_q^0-B_q^0 bar$ mixing (q = d, s). Our estimated mass of Z' boson is accessible at the experiments LHC and B-factories in near future.

hep-ph↗

arXiv2010

Visibility of dichalcogenide nanolayers

Dichalcogenides with the common formula MX2 are layered materials with electrical properties that range from semiconducting to superconducting. Here, we describe optimal imaging conditions for optical detection of ultrathin, two-dimensional dichalcogenide nanocrystals containing single, double and triple layers of MoS2, WSe2 and NbSe2. A simple optical model is used to calculate the contrast for nanolayers deposited on wafers with varying thickness of SiO2. The model is extended for imaging using the green channel of a video camera. Using AFM and optical imaging we confirm that single layers of MoS2, WSe2 and NbSe2 can be detected on 90nm and 270 nm SiO2 using optical means. By measuring contrast under broad-band green illumination we are also able to distinguish between nanostructures containing single, mono and triple layers of MoS2, WSe2 and NbSe2.

cond-mat.mes-hall↗

arXiv2005

Collective states of interacting ferromagnetic nanoparticles

Discontinuous magnetic multilayers [CoFe/Al2O3] are studied by use of magnetometry, susceptometry and numeric simulations. Soft ferromagnetic Co80Fe20 nanoparticles are embedded in a diamagnetic insulating a-Al2O3 matrix and can be considered as homogeneously magnetized superspins exhibiting randomness of size (viz. moment), position and anisotropy. Lacking intra-particle core-surface ordering, generic freezing processes into collective states rather than individual particle blocking are encountered. With increasing particle density one observes first superspin glass and then superferromagnetic domain state behavior. The phase diagram resembles that of a dilute disordered ferromagnet. Criteria for the identification of the individual phases are given.

cond-mat.mtrl-sci↗

arXiv2004

Electrical Spin Injection in Multi-Wall carbon NanoTubes with transparent ferromagnetic contacts

We report on electrical spin injection measurements on MWNTs . We use a ferromagnetic alloy Pd$_{1-x}$Ni$_{x}$ with x $\approx$ 0.7 which allows to obtain devices with resistances as low as 5.6 $kΩ$ at 300 $K$. The yield of device resistances below 100 $kΩ$, at 300 $K$, is around 50%. We measure at 2 $K$ a hysteretic magneto-resistance due to the magnetization reversal of the ferromagnetic leads. The relative difference between the resistance in the antiparallel (AP) orientation and the parallel (P) orientation is about 2%.

cond-mat.mes-hall↗

arXiv2004

The role of inner-shell excitations in electron recombination with multiply charged complex ions

We performed an overview of the inner shell excitation phenomena in the study of electron recombination with multiply charged complex ions such as Au$^{q+}$ (q=49-52) and Pb$^{53+}$. It is found the the inner shell excitations play a significant role in the low energy electron recombination. Taking into account these inner shell excitations we have calculated the energy avaraged capture cross sections. The dielectronic rate coefficients are found to be in good agreement with the experiment. We show that the contribution from the inner-shell enhances the recombinmation rate by an order of magitude. We also made an attempt to identify the resonaces observed by the experiment in Au$^{50+}$ and Pb$^{53+}$. A prediction is made for the rate enhancement in Au$^{52+}$ in which we found the configuration mixing between the doubly and the complex multiply excited states. Analyzing the statistics of eigenstate components we estimated the spreading width is about 0.85 a.u. which defines the energy range within which strong mixing takes place.

physics.atom-ph↗

arXiv2003

Intrinsic thermal vibrations of suspended doubly clamped single-wall carbon nanotubes

We report the observation of thermally driven mechanical vibrations of suspended doubly clamped carbon nanotubes, grown by chemical vapor deposition (CVD). Several experimental procedures are used to suspend carbon nanotubes. The vibration is observed as a blurring in images taken with a scanning electron microscope. The measured vibration amplitudes are compared with a model based on linear continuum mechanics.

cond-mat.mes-hall↗

arXiv2002

Cole-Cole analysis of the superspin glass system Co80Fe20/Al2O3

Ac susceptibility measurements were performed on discontinuous magnetic multilayers [Co80Fe20(t)/Al2O3(3nm)]x10, t = 0.9 and 1.0nm, by Superconducting Quantum Interference Device (SQUID) magnetometry. The CoFe forms nearly spherical ferromagnetic single-domain nanoparticles in the diamagnetic Al2O3 matrix. Due to dipolar interactions and random distribution of anisotropy axes the system exhibits a spin-glass phase. We measured the ac susceptibility as a function of temperature 20 < T < 100K at different dc fields and as a function of frequency 0.01 < f < 1000Hz. The spectral data were successfully analysed by use of the phenomenological Cole-Cole model, giving a power-law temperature dependence of the characteristic relaxation time tau_c and a high value for the polydispersivity exponent, alpha = 0.8, typical of spin glass systems.

cond-mat.dis-nn↗