Measurement of the Properties of the top Quark at DØ
To appear in the Proceedings of the
XIX. International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2011, April 11-15, Newport News, USA)
Different measurements of the properties of the top quark using up to $5.4 fb^{-1}$ collected with the D{\O} detector... more Different measurements of the properties of the top quark using up to $5.4 fb^{-1}$ collected with the D{\O} detector at the Fermilab Tevatron collider are presented. The top mass is obtained from a study of dilepton and lepton+jets final states, while the width is obtained from a combination of the measurements of the single top production via t-channel exchange and the determination of the t \rightarrow Wb branching ratio. Furthermore the measurement of the helicity of the W boson from top quark decays, a measurement of $t\bar{t}$ spin correlations and a measurement of the jet pull (color flow) in $t\bar{t}$ events are presented.
D* production in deep-inelastic scattering at low Q^2
To appear in the Proceedings of the DIS2011 conference held in Virginia, USA.
Inclusive production of D* mesons in deep-inelastic scattering at HERA is studied in the range 5 < Q^2 < 100... more
Inclusive production of D* mesons in deep-inelastic scattering at HERA is studied in the range 5 < Q^2 < 100 GeV^2 of the photon virtuality and 0.02 < y < 0.70 of the inelasticity of the scattering process. The visible range for the D* meson is pT (D*) > 1.25 GeV and |h(D*)| < 1.8.
The data were taken with the H1 detector in the years 2004 to 2007 and correspond to an integrated luminosity of 347 pb^−1. Single and double differential cross sections are measured. The results are compared to QCD predictions.
Top differential cross section measurements (Tevatron)
To appear in the Proceedings of TOP2011, 4th International Workshop on Top Quark Physics, Spain, 2011
Differential cross sections in the top quark sector measured at the Fermilab Tevatron collider are presented. CDF used... more Differential cross sections in the top quark sector measured at the Fermilab Tevatron collider are presented. CDF used 2.7 fb$^{-1}$ of data and measured the differential cross section as a function of the invariant mass of the $t\bar{t}$ system. The measurement shows good agreement with the standard model and furthermore is used to derive limits on the ratio $\kappa /M_{Pl}$ for gravitons which decay to top quarks in the Randall-Sundrum model. D0 used 1.0 fb$^{-1} of data to measure the differential cross section as a function of the transverse momentum of the top quark. The measurement shows a good agreement to the higher order perturbative QCD prediction and various predictions based on various Monte-Carlo generators.
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D* (+jets) in Deep Inelastic Scattering and Photoproduction
To appear in the Proceedings of the ICHEP 2010 (Paris).
New results on charm quark production at HERA in an increased phase space in deep-inelastic scattering and... more New results on charm quark production at HERA in an increased phase space in deep-inelastic scattering and photoproduction are discussed. Single & double-differential cross section distributions are compared to next-to-leading order QCD calculations as well as to MC@NLO in the photoproduction regime. The charm contribution to the proton structure, F_2^c(x,Q^2), is determined with different experimental techniques and finally combined.
Analytical Calculation of the Neutron Spectrum for Direct Measurement of NN Scattering at Pulsed Reactor Yaguar.
Published in Physics of Atomic Nuclei (Yadernaya Fizika v.72, n.1, p.1-6), v.72, n.1, p.36-41, 2009; Proc. XVI International seminar on Interaction of Neutrons with Nuclei, Dubna June 11-14 2008. Dubna 2009.
Instead of Monte Carlo calculations performed by groups with numerous authors I used a standard analytical approach of neutron interaction with a gas composed by other neutrons. It is much simpler and everyone can check my calculations.
The paper was first submitted to J. Phys. G, where Monte Carlo calculations were published. And the referee rejected it because analytical solution, he believes, adds nothing new to Monte-Carlo calculation made by a large group of ambitious people. I tried to publish this referee report in Physics of Atomic Nuclei, when the paper was accepted there, but failed. I was not able to publish it not in arXiv, and not in JINR Communication E3-2008-49. The story of myattempts can be found here at the end of the paper in section: history of submissions and rejections.
Analytical calculation of a single neutron detector counts per
YAGUAR reactor pulse is presented and comparison... more
Analytical calculation of a single neutron detector counts per
YAGUAR reactor pulse is presented and comparison with coincidence scheme is given.
Limits on a nucleon-nucleon monopole-dipole coupling from spin relaxation of polarized ultra-cold neutrons in traps
Co-authored with Yu.N. Pokotilovskiy
Published in European Physical Journal C - Particles and Fields, v. 64, n. 1, pp. 19-23 (2009).
We calculated probability of UCN depolarization at reflection from a nonmagnetic walls in presence of axion field, and then extracted the limits of this field from comparison with the limits of depolarisation in EDM experiments.
A new limit is presented on the axion-like monopole-dipole
P,T-non-invariant interaction in a range $(10^{-4} ---... more
A new limit is presented on the axion-like monopole-dipole
P,T-non-invariant interaction in a range $(10^{-4} --- 1)$ cm.
The spin-dependent nucleon-nucleon potential between neutrons
and nucleons of the walls of the cavity containing ultra-cold
neutrons should affect the neutron depolarization probability at
their reflection from the walls.
The limit is obtained from existing data on the ultra-cold neutron
depolarization probability per one collision with the walls.
From Flavour to SUSY Flavour Models
Co-authored with Stefan Antusch, Lorenzo Calibbi, Vinzenz Maurer; published in Nucl.Phys. B852 (2011) 108-148
If supersymmetry (SUSY) will be discovered, successful models of flavour not only have to provide an explanation of... more If supersymmetry (SUSY) will be discovered, successful models of flavour not only have to provide an explanation of the flavour structure of the Standard Model fermions, but also of the flavour structure of their scalar superpartners. We discuss aspects of such "SUSY flavour" models, towards predicting both flavour structures, in the context of supergravity (SUGRA). We point out the importance of carefully taking into account SUSY-specific effects, such as 1-loop SUSY threshold corrections and canonical normalization, when fitting the model to the data for fermion masses and mixings. This entangles the flavour model with the SUSY parameters and leads to interesting predictions for the sparticle spectrum. We demonstrate these effects by analyzing an example class of flavour models in the framework of an SU(5) Grand Unified Theory with a family symmetry with real triplet representations. For flavour violation through the SUSY soft breaking terms, the class of models realizes a scheme we refer to as "Trilinear Dominance", where flavour violation effects are dominantly induced by the trilinear terms.
Right unitarity triangles and tri-bimaximal mixing from discrete symmetries and unification
Co-authored with Stefan Antusch, Stephen F. King, Christoph Luhn; published in Nucl.Phys. B850 (2011) 477-504
We propose new classes of models which predict both tri-bimaximal lepton mixing and a right-angled... more We propose new classes of models which predict both tri-bimaximal lepton mixing and a right-angled Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle, alpha approximately 90 degrees. The ingredients of the models include a supersymmetric (SUSY) unified gauge group such as SU(5), a discrete family symmetry such as A4 or S4, a shaping symmetry including products of Z2 and Z4 groups as well as spontaneous CP violation. We show how the vacuum alignment in such models allows a simple explanation of alpha approximately 90 degrees by a combination of purely real or purely imaginary vacuum expectation values (vevs) of the flavons responsible for family symmetry breaking. This leads to quark mass matrices with 1-3 texture zeros that satisfy the phase sum rule and lepton mass matrices that satisfy the lepton mixing sum rule together with a new prediction that the leptonic CP violating oscillation phase is close to either 0, 90, 180, or 270 degrees depending on the model, with neutrino masses being purely real (no complex Majorana phases). This leads to the possibility of having right-angled unitarity triangles in both the quark and lepton sectors.
A Case Study on ΣΛ Conversion In P-Shell Hypernuclei
MHS Bukhari, Turk. J. Physics 34, 65-71 (2010)
The important process of Sigma-Lambda conversion is presented and discussed in this report and a case example has been... more
The important process of Sigma-Lambda conversion is presented and discussed in this report and a case example has been presented reviewing some cross sections and decay widths calculated for the process in a p-shell hypernucleus in recent studies.
Key Words: Sigma-Lambda conversion, hypernucleus
Quark mixing sum rules and the right unitarity triangle
Co-authored with Stefan Antusch, Stephen F. King, Michal Malinsky, published under Phys.Rev.D81:033008,2010
In analogy with the recently proposed lepton mixing sum rules, we derive quark mixing sum rules for the case of... more In analogy with the recently proposed lepton mixing sum rules, we derive quark mixing sum rules for the case of hierarchical quark mass matrices with 1-3 texture zeros, in which the separate up and down type 1-3 mixing angles are approximately zero, and $V_{ub}$ is generated from $V_{cb}$ as a result of 1-2 up type quark mixing. Using the sum rules, we discuss the phenomenological viability of such textures, including up to four texture zeros, and show how the right-angled unitarity triangle, i.e., $\alpha \approx 90^\circ$, can be accounted for by a remarkably simple scheme involving real mass matrices apart from a single element being purely imaginary. In the framework of grand unified theories we show how the quark and lepton mixing sum rules may combine to yield an accurate prediction for the reactor angle.
Large corrections to electroweak parameters in technicolor theories
by John Terning
Co-authored with B. Holdom
We study the leading radiative corrections to various weak interaction parameters due to new heavy particles. We use... more We study the leading radiative corrections to various weak interaction parameters due to new heavy particles. We use an effective chiral lagrangian and input from low energy QCD to confirm the large size of these effects in technicolor theories.
Cosmology of Brane Models with Radion Stabilization
by John Terning
Co-authored with Csaba Csaki, Michael Graesser, Lisa Randall
We analyze the cosmology of the Randall-Sundrum model and that of compact brane models in general in the presence of a... more We analyze the cosmology of the Randall-Sundrum model and that of compact brane models in general in the presence of a radius stabilization mechanism. We find that the expansion of our universe is generically in agreement with the expected effective four dimensional description. The constraint (which is responsible for the appearance of non-conventional cosmologies in these models) that must be imposed on the matter densities on the two branes in the theory without a stabilized radius is a consequence of requiring a static solution even in the absence of stabilization. Such constraints disappear in the presence of a stablizing potential, and the ordinary FRW (Friedmann-Robertson-Walker) equations are reproduced, with the expansion driven by the sum of the physical values of the energy densities on the two branes and in the bulk. For the case of the Randall-Sundrum model we examine the kinematics of the radion field, and find that corrections to the standard FRW equations are small for temperatures below the weak scale. We find that the radion field has renormalizable and unsuppressed couplings to Standard Model particles after electroweak symmetry breaking. These couplings may have important implications for collider searches. We comment on the possibility that matter off the TeV brane could serve as a dark matter candidate.
Gauge Theories on an Interval: Unitarity without a Higgs
by John Terning
Co-authored with C.Csaki, C.Grojean, H.Murayama, L.Pilo
We consider extra dimensional gauge theories on an interval. We first review the derivation of the consistent boundary... more We consider extra dimensional gauge theories on an interval. We first review the derivation of the consistent boundary conditions (BC's) from the action principle. These BC's include choices that give rise to breaking of the gauge symmetries. The boundary conditions could be chosen to coincide with those commonly applied in orbifold theories, but there are many more possibilities. To investigate the nature of gauge symmetry breaking via BC's we calculate the elastic scattering amplitudes for longitudinal gauge bosons. We find that using a consistent set of BC's the terms in these amplitudes that explicitly grow with energy always cancel without having to introduce any additional scalar degree of freedom, but rather by the exchange of Kaluza--Klein (KK) gauge bosons. This suggests that perhaps the SM Higgs could be completely eliminated in favor of some KK towers of gauge fields. We show that from the low-energy effective theory perspective this seems to be indeed possible. We display an extra dimensional toy model, where BC's introduce a symmetry breaking pattern and mass spectrum that resembles that in the standard model.
Towards a Realistic Model of Higgsless Electroweak Symmetry Breaking
by John Terning
Co-authored with Csaba Csaki, Christophe Grojean, Luigi Pilo
We present a 5D gauge theory in warped space based on a bulk SU(2)_L x SU(2)_R x U(1)_(B-L) gauge group where the... more We present a 5D gauge theory in warped space based on a bulk SU(2)_L x SU(2)_R x U(1)_(B-L) gauge group where the gauge symmetry is broken by boundary conditions. The symmetry breaking pattern and the mass spectrum resembles that in the standard model (SM). To leading order in the warp factor the rho parameter and the coupling of the Z (or equivalently the S-parameter) are as in the SM, while corrections are expected at the level of a percent. From the AdS/CFT point of view the model presented here can be viewed as the AdS dual of a (walking) technicolor-like theory, in the sense that it is the presence of the IR brane itself that breaks electroweak symmetry, and not a localized Higgs on the IR brane (which should be interpreted as a composite Higgs model). This model predicts the lightest W, Z and photon resonances to be at around 1.2 TeV, and no fundamental (or composite) Higgs particles.
The AdS/QCD Correspondence: Still Undelivered
by John Terning
Co-authored with Csaba Csaki and Matthew Reece
We consider the particle spectrum and event shapes in large N gauge theories in different regimes of the... more We consider the particle spectrum and event shapes in large N gauge theories in different regimes of the short-distance 't Hooft coupling, lambda. The mesons in the small lambda limit should have a Regge spectrum in order to agree with perturbation theory, while generically the large lambda theories with gravity duals produce spectra reminiscent of KK modes. We argue that these KK-like states are qualitatively different from QCD modes: they are deeply bound states which are sensitive to short distance interactions rather than the flux tube-like states expected in asymptotically free, confining gauge theories. In addition, we also find that the characteristic event shapes for the large lambda theories with gravity duals are close to spherical, very different from QCD-like (small lambda, small N) and Nambu-Goto-like (small lambda, large N) theories which have jets. This observation is in agreement with the conjecture of Strassler on event shapes in large 't Hooft coupling theories, which was recently proved by Hofman and Maldacena for the conformal case. This conclusion does not change even when considering soft-wall backgrounds in the gravity dual. The picture that emerges is the following: theories with small and large lambda are qualitatively different, while theories with small and large N are qualitatively similar. Thus it seems that it is the relative smallness of the 't Hooft coupling in QCD that prevents a reliable AdS/QCD correspondence from emerging, and that reproducing characteristic QCD-like behavior will require genuine stringy dynamics to be incorporated into any putative dual theory.
Electroweak Symmetry Breaking From Monopole Condensation
by John Terning
Co-authored with Csaba Csaki, Yuri Shirman,
We examine models where massless chiral fermions with both "electric" and "magnetic" hypercharges... more We examine models where massless chiral fermions with both "electric" and "magnetic" hypercharges could form condensates. When some of the fermions are also electroweak doublets such condensates can break the electroweak gauge symmetry down to electromagnetism in the correct way. Since ordinary hypercharge is weakly coupled at the TeV scale, magnetic hypercharge is strongly coupled and can potentially drive the condensation. Such models are similar to technicolor, but with hypercharge playing the role of the technicolor gauge group, so the standard model gauge group breaks itself. A heavy top mass can be generated via the Rubakov-Callan effect and could thus decouple the scale of flavor physics from the electroweak scale.