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N. V. Krasnikov

Publications and source records attributed to N. V. Krasnikov.

At least 73 records · Page 4Linked to original sources
arXiv2012

The relation between frequentist confidence intervals and Bayesian credible intervals

We investigate the relation between frequentist and Bayesian approaches. Namely, we find the "frequentist" Bayes prior π_{f}(λ,x_{obs}) = -\frac{\int_{-\infty}^{x_{obs}}\frac{\partial f(x,λ)}{\partial λ}dx}{f(x_{obs},λ)} (here f(x,λ) is the probability density) for which the results of frequentist and Bayes approaches to the determination of confidence intervals coincide. In many cases (but not always) the "frequentist" prior which reproduces frequentist results coincides with the Jeffreys prior.

physics.data-an↗
arXiv2012

Modified frequentist determination of confidence intervals for Poisson distribution

We propose modified frequentist definitions for the determination of confidence intervals for the case of Poisson statistics. We require that 1-β^{'} \geq \sum_{n=o}^{n_{obs}+k} P(n|λ) \geq α^{'}. We show that this definition is equivalent to the Bayesian method with prior π(λ) \sim λ^{k}. Other generalizations are also considered. In particular, we propose modified symmetric frequentist definition which corresponds to the Bayes approach with the prior function π(λ) \sim 1/2(1 + \frac{n_{obs}}λ). Modified frequentist definitions for the case of nonzero background are proposed.

physics.data-an↗
arXiv2010

On combining significances. Some trivial examples

For Poisson distribution $Pois(n, λ)$ with $λ\gg 1$, $n \gg 1$ we propose to determine significance as $S = \frac{n_{obs}-λ}{\sqrtλ}$. The significance $S$ coincides up to sign with often used significance. For experiments which measure the same quantities the natural but not unique rule for significance combining is $S_{comb}(S_1, S_2) = \frac{S_1σ_1+S_2σ_2}{\sqrt{σ^2_1+σ^2_2}}$, where $σ_1$ and $σ_2$ are variations. We also propose the rule for significances combining for the case with systematic errors.

physics.data-an↗
arXiv2010

LHC $Z^`$ discovery potential for models with continuously distributed mass

We study the Large Hadron Collider (LHC) discovery potential for $Z^`$ models with continuously distributed mass for $\sqrt{s} = 7, 10$ and 14 TeV centre-of-mass energies. One of possible LHC signatures for such models is the existence of broad resonance in Drell-Yan reaction $pp \to Z^` + ... \to l^+l^- + ...$.

hep-ph↗
arXiv2009

Fields with continuously distributed mass

We describe local field theories with continuously distributed mass. Such models can be realized as models in d space-time with Poincare invariance only in four-dimensional space-time. We also discuss some possible phenomenological consequences. Namely, we show that the Higgs boson phenomenology in the SM extension with continuously distributed Higgs boson mass can differ in a drastic way from the SM Higgs boson phenomenology.

hep-ph↗
arXiv2009

The MSSM with Large Gluino Mass

We study the Minimal Supersymmetric Standard Model (MSSM) with large gluino mass m_{\tilde{g}} >> 1 TeV. In particular, we discuss the LHC supersymmetry discovery signatures with n leptons + jets + E^{miss}_T, n >= 0 for the MSSM with large gluino mass. We show that for some relations among squark and neutralino masses leptonic signatures with n leptons + jets + E^{miss}_T, n >= 1 do not allow to discover supersymmetry at the LHC and the only supersymmetry discovery signature remains the signature with no leptons + jets + E^{miss}_T. Moreover, for LSP mass close to squark masses the LHC discovery potential for this signature is strongly reduced.

hep-ph↗
arXiv2008

Invisible $Z\prime$ as a probe of extra dimensions at the CERN LHC

A class of extra dimensional models with a warped metric predict tunneling of a massive particle localized on our brane and escaping into additional dimensions. The experimental signature of this effect is the disappearance of the particle from our world, i.e. the particle $\to invisible$ decay. We point out that measurements of $Z\prime \to invisible$ decay width of a new heavy gauge boson $Z\prime$ at the CERN LHC can be effectively used to probe the existence of large extra dimensions. This result enhances motivations for a more sensitive search and study for this decay mode and suggests additional direction for testing extra dimensions in collider experiments.

hep-ph↗
arXiv2008

LHC signatures for Z` models with continuously distributed mass

We discuss phenomenological consequences of renormalizable Z` models with continuously distributed mass. We point out that one of possible LHC signatures for such nodel is the existence of broad resonance in Drell-Yan reaction $pp \to Z^{`} \to l^+l^-$.

hep-ph↗
arXiv2007

Unparticle as a field with continuously distributed mass

We point out that the notion of an unparticle, recently introduced by Georgi, can be interpreted as a particular case of a field with continuously distributed mass considered in ref.\cite{14}. We also point out that the simplest renormalizable extension of the $SU_c(3)\otimes SU_L(2)\otimes U(1)$ Standard Model is the extension with the replacement of the U(1) gauge propagator $\frac{1}{k^2} \to \frac{1}{k^2} + \int _0^{\infty}\frac{ρ(t)}{-t+k^2 +iε}dt$ with $\int_0^{\infty}ρ(t)dt < \infty $.

hep-ph↗
arXiv2007

Searching for energetic cosmic axions in a laboratory experiment: testing the PVLAS anomaly

Astrophysical sources of energetic gamma rays provide the right conditions for maximal mixing between (pseudo)scalar (axion-like) particles and photons if their coupling is as strong as suggested by the PVLAS claim. This is independent of whether or not the axion interaction is standard at all energies or becomes supressed in the extreme conditions of the stellar interior. The flux of such particles through the Earth could be observed using a metre long, Tesla strength superconducting solenoid thus testing the axion interpretation of the PVLAS anomaly. The rate of events in CAST caused by axions from the Crab pulsar is also estimated for the PVLAS-favoured parameters.

hep-ph↗
arXiv2007

Search for millicharged particles in reactor neutrino experiments: a probe of the PVLAS anomaly

It has been recently suggested that the vacuum magnetic dichroism observed by the PVLAS experiment could be explained by the pair production of a new light, m ~0.1 eV, millicharged, q ~ 3 10^{-6} e, fermions. In addition, it has been pointed out that millicharged particles with q > 10^{-9} e appear naturally in models based on the string theory. We show that low energy reactor neutrino experiments provide a sensitive probe of millicharged particles. Considering, as an example, recent results of the TEXONO experiment searching for neutrino magnetic moment, a new upper bound q < 10^{-5} e for the mass region m < 1 keV is derived. These results enhance motivations for a more sensitive search for such particles in near future experiments. Furthemore, a direct experimental limit on the electric charge of the electron antineutrino q < 3.7 10^{-12} e is obtained.

hep-ph↗
arXiv2006

Using the e^{+/-} mu^{-/+} + E^{miss}_T signature in the search for supersymmetry and lepton flavour violation in neutralino decays

The LHC (CMS) discovery potential of the $e^{\pm}μ^{\mp} + E^{miss}_T$ signature in the search for supersymmetry and lepton flavour violation in neutralino decays is studied. A detailed study is done for the CMS test points LM1-LM9. It is shown that for the point LM1 it is possible to detect lepton flavour violation in neutralino decays with lepton flavour violating branching $Br(\tildeχ^0_2 \to μ^{\pm}e^{\mp}\tildeχ^0_1) \geq 0.04 Br(\tildeχ^0_2 \to e^{+}e^{-}\tildeχ^0_1, μ^{+}μ^{-} \tildeχ^0_1)$ for an integral luminosity $10 fb^{-1}$. A discovery potential in the mSUGRA-SUSY scenario with $\tan β= 10, ~sign(μ) = +$ in the $(m_0, m_{1/2})$ plane using the $e^{\pm}μ^{\mp} + E^{miss}_T$ signature is determined.

hep-ph↗
arXiv2005

The Bayesian Effects in Measurement of the Asymmetry of Poisson Flows

As it follows from the interrelation of Gamma and Poisson distributions the observed value of asymmetry for Poisson flows of events has the bias. The Monte Carlo experiment confirms the presence of this bias between the observed and initial asymmetries. The obtained results allow to correct the estimation of the asymmetry of flow rates.

physics.data-an↗
arXiv2004

Sleptons at post-WMAP benchmark points at LHC(CMS)

We study a possibility to detect sleptons at post-WMAP benchmark points at LHC(CMS). We find that at $L_{tot}=30 fb^{-1}$ it would be possible to detect sleptons at points A, B, C, D, G. We also investigate the production and decays of right and left sleptons separately. We find that at $L_{tot}=30 fb^{-1}$ it would be possible to detect right sleptons with a mass up to 200 GeV and left ones with a mass up to 300 GeV.

hep-ph↗
arXiv2003

The probability of making a correct decision in hypotheses testing as estimator of quality of planned experiments

In the report the approach to estimation of quality of planned experiments is considered. This approach is based on the analysis of uncertainty, which will take place under the future hypotheses testing about the existence of a new phenomenon in Nature. The probability of making a correct decision in hypotheses testing is proposed as estimator of quality of planned experiments. This estimator allows to take into account systematics and statistical uncertainties in determination of signal and background rates.

physics.data-an↗
arXiv2003

Prospects of detecting massive isosinglet neutrino at LHC in the CMS detector

A possibility to search for a heavy isosinglet (sterile) neutrino using its decay mode $ν_s \to l^{\pm} + 2 jets$ in the $S$ - channel production $pp \to W^* + X \to l^{\pm}ν_s + X$ in the CMS experiment is studied. The only assumption about the heavy neutrino is its nonzero mixing with $ν_e$ or $ν_μ$. The corresponding CMS discovery potential expressed in terms of the heavy neutrino mass and the mixing parameter between the heavy and light neutrino is determined. It is shown that the heavy neutrino with a mass up to 800 $GeV$ could be detected in CMS. We also investigate the production of the heavy neutrino $N_l$ mixed with $ν_e$ and/or $ν_μ$ in the $SU_C(3) \otimes SU_L(2) \otimes SU_R(2)\otimes U(1)$ model through the reaction $pp \to W_R + X \to l^{\pm}N_l + X$ with the same heavy neutrino decay channel as above. We find that for $M_{W_R} < 3 TeV$ it is possible to discover the heavy neutrino with a mass up to $0.75 \cdot M_{W_R}$.

hep-ph↗
arXiv2003

Search for new physics at LHC

We review the search for new physics to be performed at the Large Hadron Collider(LHC). Namely, we review the expectations for the Higgs boson, supersymmetry and exotica detection at LHC. We also describe the main parameters of the CMS and ATLAS detectors.

hep-ph↗