The Experts below are selected from a list of 411411 Experts worldwide ranked by ideXlab platform
C Fabjan - One of the best experts on this subject based on the ideXlab platform.
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search for New Physics in events with same sign dileptons and jets in pp collisions at s 8 tev
Journal of High Energy Physics, 2014Co-Authors: S Chatrchyan, A M Sirunyan, V Khachatryan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Ero, C FabjanAbstract:A search for New Physics is performed based on events with jets and a pair of isolated, same-sign leptons. The results are obtained using a sample of proton-proton collision data collected by the CMS experiment at a centre-of-mass energy of 8 TeV at the LHC, corresponding to an integrated luminosity of 19.5 fb−1. In order to be sensitive to a wide variety of possible signals beyond the standard model, multiple search regions defined by the missing transverse energy, the hadronic energy, the number of jets and b-quark jets, and the transverse momenta of the leptons in the events are considered. No excess above the standard model background expectation is observed and constraints are set on a number of models for New Physics, as well as on the same-sign top-quark pair and quadruple-top-quark production cross sections. Information on event selection efficiencies is also provided, so that the results can be used to confront an even broader class of New Physics models.
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search for New Physics in events with same sign dileptons and b jets in pp collisions at s 8 tev
Journal of High Energy Physics, 2013Co-Authors: S Chatrchyan, A M Sirunyan, V Khachatryan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Ero, C FabjanAbstract:A search for New Physics is performed using isolated same-sign dileptons with at least two b-quark jets in the final state. Results are based on a 4.98 inverse femtobarn sample of proton-proton collisions at a centre-of-mass energy of 7 TeV collected by the CMS detector. No excess above the standard model background is observed. Upper limits at 95% confidence level are set on the number of events from non-standard-model sources. These limits are used to set constraints on a number of New Physics models. Information on acceptance and efficiencies are also provided so that the results can be used to confront additional models in an approximate way.
Diptimoy Ghosh - One of the best experts on this subject based on the ideXlab platform.
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diagnosing New Physics in b to c tau nu_ tau decays in the light of the recent babar result
Physical Review D, 2012Co-Authors: Alakabha Datta, Murugeswaran Duraisamy, Diptimoy GhoshAbstract:The BABAR Collaboration has recently reported the measurement of the ratio of the branching fractions of $\overline{B}\ensuremath{\rightarrow}D({D}^{*}){\ensuremath{\tau}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ to $\overline{B}\ensuremath{\rightarrow}D({D}^{*}){\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}}$ which deviates from the Standard Model prediction by $2\ensuremath{\sigma}$ ($2.7\ensuremath{\sigma}$). This deviation goes up to $3.4\ensuremath{\sigma}$ level when the two measurements in the $D$ and ${D}^{*}$ modes are taken together and could indicate New Physics. Using an effective Lagrangian for the New Physics, we study the implication of these results and calculate other observables that can shed light on the nature of the New Physics. We show that the measurements of the forward-backward asymmetries and the $\ensuremath{\tau}$ and ${D}^{*}$ polarization fractions can be distinguished among the various couplings of the New Physics operators.
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diagnosing New Physics in b to c tau nu_ tau decays in the light of the recent babar result
Physical Review D, 2012Co-Authors: Alakabha Datta, Murugeswaran Duraisamy, Diptimoy GhoshAbstract:The BaBar Collaboration has recently reported the measurement of the ratio of the branching fractions of $\bar{B} \to D(D^{*}) \tau^{-} \bar{\nu_\tau}$ to $\bar{B} \to D(D^{*}) \ell^{-} \bar{\nu_\ell}$ which deviates from the Standard Model prediction by 2$\sigma$(2.7$\sigma$). This deviation goes up to 3.4$\sigma$ level when the two measurements in the $D$ and $D^*$ modes are taken together and could indicate New Physics. Using an effective Lagrangian for the New Physics we study the implication of these results and calculate other observables that can shed light on the nature of the New Physics. We show that the measurements of the forward-backward asymmetries and the $\tau$ and $D^*$ polarization fractions can distinguish among the various couplings of the New Physics operators.
S Chatrchyan - One of the best experts on this subject based on the ideXlab platform.
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search for New Physics in events with same sign dileptons and jets in pp collisions at s 8 tev
Journal of High Energy Physics, 2014Co-Authors: S Chatrchyan, A M Sirunyan, V Khachatryan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Ero, C FabjanAbstract:A search for New Physics is performed based on events with jets and a pair of isolated, same-sign leptons. The results are obtained using a sample of proton-proton collision data collected by the CMS experiment at a centre-of-mass energy of 8 TeV at the LHC, corresponding to an integrated luminosity of 19.5 fb−1. In order to be sensitive to a wide variety of possible signals beyond the standard model, multiple search regions defined by the missing transverse energy, the hadronic energy, the number of jets and b-quark jets, and the transverse momenta of the leptons in the events are considered. No excess above the standard model background expectation is observed and constraints are set on a number of models for New Physics, as well as on the same-sign top-quark pair and quadruple-top-quark production cross sections. Information on event selection efficiencies is also provided, so that the results can be used to confront an even broader class of New Physics models.
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search for New Physics in events with same sign dileptons and b jets in pp collisions at s 8 tev
Journal of High Energy Physics, 2013Co-Authors: S Chatrchyan, A M Sirunyan, V Khachatryan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Ero, C FabjanAbstract:A search for New Physics is performed using isolated same-sign dileptons with at least two b-quark jets in the final state. Results are based on a 4.98 inverse femtobarn sample of proton-proton collisions at a centre-of-mass energy of 7 TeV collected by the CMS detector. No excess above the standard model background is observed. Upper limits at 95% confidence level are set on the number of events from non-standard-model sources. These limits are used to set constraints on a number of New Physics models. Information on acceptance and efficiencies are also provided so that the results can be used to confront additional models in an approximate way.
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Search for New Physics with same-sign isolated dilepton events with jets and missing transverse energy
Physical Review Letters, 2012Co-Authors: S Chatrchyan, M. Besancon, S. Choudhury, M. Dejardin, D. Denegri, B. Fabbro, J.l. Faure, F. Ferri, S. Ganjour, A. GivernaudAbstract:A search for New Physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for New Physics is found. The observations are used to set upper limits on possible New Physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of New Physics scenarios, information on the event selection, detector response, and efficiencies is provided.
M Lindner - One of the best experts on this subject based on the ideXlab platform.
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atmospheric trident production for probing New Physics
Physics Letters B, 2017Co-Authors: M Lindner, Werner RodejohannAbstract:Abstract We propose to use atmospheric neutrinos as a powerful probe of New Physics beyond the Standard Model via neutrino trident production. The final state with double muon tracks simultaneously produced from the same vertex is a distinctive signal at large Cherenkov detectors. We calculate the expected event numbers of trident production in the Standard Model. To illustrate the potential of this process to probe New Physics we obtain the sensitivity on New vector/scalar bosons with coupling to muon and tau neutrinos.
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New Physics effects on neutrinoless double beta decay from right handed current
Journal of High Energy Physics, 2015Co-Authors: M Lindner, Sudhanwa PatraAbstract:We study the impact of New Physics contributions to neutrinoless double beta decay arising from right-handed current in comparison with the standard mechanism. If the light neutrinos obtain their masses from Type-II seesaw within left-right symmetric model, where the Type-I contribution is suppressed to negligible extent, the right-handed PMNS matrix is the same as its left-handed counterpart, making it highly predictable and testable at next-generation experiments. It is very attractive, especially with recent cosmological constraint favoring the normal hierarchy under which the neutrinoless double beta decay is too small to be observed unless New Physics appears as indicated by the recent diboson excess observed at ATLAS. The relative contributions from left- and right-handed currents can be reconstructed with the ratio between lifetimes of two different isotopes as well as the ratio of nuclear matrix elements. In this way, the theoretical uncertainties in the calculation of nuclear matrix elements can be essentially avoided. We also discuss the interplay of neutrinoless double beta decay measurements with cosmology, beta decay, and neutrino oscillation.
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New Physics effects on neutrinoless double beta decay from right handed current
arXiv: High Energy Physics - Phenomenology, 2015Co-Authors: M Lindner, Sudhanwa PatraAbstract:We study the impact of New Physics contributions to neutrinoless double beta decay arising from right-handed current in comparison with the standard mechanism. If the light neutrinos obtain their masses from Type-II seesaw within left-right symmetric model, where the Type-I contribution is suppressed to negligible extent, the right-handed PMNS matrix is the same as its left-handed counterpart, making it highly predictable and can be tested at next-generation experiments. It is very attractive, especially with recent cosmological constraint favoring the normal hierarchy under which the neutrinoless double beta decay is too small to be observed unless New Physics appears as indicated by the recent diboson excess observed at ATLAS. The relative contributions from left- and right-handed currents can be reconstructed with the ratio between lifetimes of two different isotopes as well as the ratio of nuclear matrix elements. In this way, the theoretical uncertainties in the calculation of nuclear matrix elements can be essentially avoided. We also discuss the interplay of neutrinoless double beta decay measurements with cosmology, beta decay, and neutrino oscillation.
Martin Gonzalezalonso - One of the best experts on this subject based on the ideXlab platform.
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New Physics searches in nuclear and neutron beta decay arxiv
Progress in Particle and Nuclear Physics, 2019Co-Authors: Martin Gonzalezalonso, O Naviliatcuncic, N SeverijnsAbstract:Abstract The status of tests of the standard electroweak model and of searches for New Physics in allowed nuclear β decay and neutron decay is reviewed including both theoretical and experimental developments. The sensitivity and complementarity of recent and ongoing experiments are discussed with emphasis on their potential to look for New Physics. Measurements are interpreted using a model-independent effective field theory approach enabling to recast the outcome of the analysis in many specific New Physics models. Special attention is given to the connection that this approach establishes with high-energy Physics. A New global fit of available β -decay data is performed incorporating, for the first time in a consistent way, superallowed 0 + → 0 + transitions, neutron decay and nuclear decays. The constraints on exotic scalar and tensor couplings involving left- or right-handed neutrinos are determined while a constraint on the pseudoscalar coupling from neutron decay data is obtained for the first time as well. The values of the vector and axial–vector couplings, which are associated within the standard model to V u d and g A respectively, are also updated. The ratio between the axial and vector couplings obtained from the fit under standard model assumptions is C A ∕ C V = − 1 . 27510 ( 66 ) . The relevance of the various experimental inputs and error sources is critically discussed and the impact of ongoing measurements is studied. The complementarity of the obtained bounds with other low- and high-energy probes is presented including ongoing searches at the Large Hadron Collider.
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New Physics searches in nuclear and neutron beta decay
arXiv: High Energy Physics - Phenomenology, 2018Co-Authors: Martin Gonzalezalonso, O Naviliatcuncic, N SeverijnsAbstract:The status of tests of the standard electroweak model and of searches for New Physics in allowed nuclear $\beta$ decay and neutron decay is reviewed including both theoretical and experimental developments. The sensitivity and complementarity of recent and ongoing experiments are discussed with emphasis on their potential to look for New Physics. Measurements are interpreted using a model-independent effective field theory approach enabling to recast the outcome of the analysis in many specific New Physics models. Special attention is given to the connection that this approach establishes with high-energy Physics. A New global fit of available $\beta$-decay data is performed incorporating, for the first time in a consistent way, superallowed $0^+\to 0^+$ transitions, neutron decay and nuclear decays. The constraints on exotic scalar and tensor couplings involving left- or right-handed neutrinos are determined while a constraint on the pseudoscalar coupling from neutron decay data is obtained for the first time as well. The values of the vector and axial-vector couplings, which are associated within the standard model to $V_{ud}$ and $g_A$ respectively, are also updated. The ratio between the axial and vector couplings obtained from the fit under standard model assumptions is $C_A/C_V = -1.27510(66)$. The relevance of the various experimental inputs and error sources is critically discussed and the impact of ongoing measurements is studied. The complementarity of the obtained bounds with other low- and high-energy probes is presented including ongoing searches at the Large Hadron Collider.
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renormalization group evolution of New Physics contributions to semi leptonic meson decays
Physics Letters B, 2017Co-Authors: Martin Gonzalezalonso, Jorge Martin Camalich, Kin MimouniAbstract:Abstract We study the renormalization group evolution (RGE) of New Physics contributions to (semi)leptonic charged-current meson decays, focusing on operators involving a chirality flip at the quark level. We calculate their evolution under electroweak and electromagnetic interactions, including also the three-loop QCD running and provide numerical formulas that allow us to connect the values of the corresponding Wilson coefficients from scales at the TeV to the low-energy scales. The large mixing of the tensor operator into the (pseudo)scalar ones has important phenomenological implications, such as the RGE of New Physics bounds obtained from light quark decays or in b → c l ν transitions. For instance, we study scenarios involving tensor effective operators, which have been proposed in the literature to address the B -decay anomalies, most notably those concerning the R D ( ⁎ ) ratios. We conclude that the loop effects are important and should be taken into account in the analysis of these processes, especially if the operators are generated at an energy scale of ∼1 TeV or higher.
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global effective field theory analysis of New Physics effects in semi leptonic kaon decays
Journal of High Energy Physics, 2016Co-Authors: Martin Gonzalezalonso, Jorge Martin CamalichAbstract:We analyze the decays K → πlν and P → lν (P = K, π, l = e, μ) using a low-energy Effective-Field-Theory approach to parametrize New Physics and study the complementarity with baryon β decays. We then provide a road map for a global analysis of the experimental data, with all the Wilson coefficients simultaneously, and perform a fit leading to numerical bounds for them and for V us . A prominent result of our analysis is a reinterpretation of the well-known V ud − V us diagram as a strong constraint on New Physics. Finally, we reinterpret our bounds in terms of the SU(2) L × U(1) Y -invariant operators, provide bounds to the corresponding Wilson coefficients at the TeV scale and compare our results with collider searches at the LHC.
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global effective field theory analysis of New Physics effects in semi leptonic kaon decays
Journal of High Energy Physics, 2016Co-Authors: Martin Gonzalezalonso, Jorge Martin CamalichAbstract:We analyze the decays $K\to\pi\ell\nu$ and $P\to\ell\nu$ ($P=K,\pi$, $\ell=e,\,\mu$) using a low-energy Effective-Field-Theory approach to parametrize New Physics and study the complementarity with baryon $\beta$ decays. We then provide a road map for a global analysis of the experimental data, with all the Wilson coefficients simultaneously, and perform a fit leading to numerical bounds for them and for $V_{us}$. A prominent result of our analysis is a reinterpretation of the well-known $V_{ud}-V_{us}$ diagram as a strong constraint on New Physics. Finally, we reinterpret our bounds in terms of the $SU(2)_L\times~U(1)_Y$-invariant operators, provide bounds to the corresponding Wilson coefficients at the TeV scale and compare our results with collider searches at the LHC.
