# Physics Commons™

Selected Works

High energy physics phenomenology

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## Full-Text Articles in Physics

Dijet Signals For Low Mass Strings At The Lhc, Luis A. Anchordoqui, Haim Goldberg, Dieter Lüst, Satoshi Nawata, Stephan Stieberger, Tomasz T. Taylor Feb 2011

#### Dijet Signals For Low Mass Strings At The Lhc, Luis A. Anchordoqui, Haim Goldberg, Dieter Lüst, Satoshi Nawata, Stephan Stieberger, Tomasz T. Taylor

##### Tomasz Taylor

We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we discuss possible signals of string physics at the Large Hadron Collider (LHC). In such D-brane constructions, the dominant contributions to full-fledged string amplitudes for all the common QCD parton subprocesses leading to dijets are completely independent of the details of compactification, and can be evaluated in ...

Direct Production Of Lightest Regge Resonances, W. Z. Feng, D. Lüst, S. Stieberger, T. R. Taylor Feb 2011

#### Direct Production Of Lightest Regge Resonances, W. Z. Feng, D. Lüst, S. Stieberger, T. R. Taylor

##### Tomasz Taylor

We discuss direct production of Regge excitations in the collisions of massless four-dimensional superstring states, focusing on the first excited level of open strings ending on D-branes extending into higher dimensions. We construct covariant vertex operators and identify universal'' Regge states with the internal parts either trivial or determined by the world-sheet SCFT describing superstrings propagating on an arbitrary Calabi-Yau manifold. We evaluate the amplitudes involving one such massive state and up to three massless ones and express them in the helicity basis. The most important phenomenological applications of our results are in the context of low-mass string (and large ...

Effects Of Large Cp Phases On The Proton Lifetime In Supersymmetric Unification, Tarek Ibrahim, Pran Nath Feb 2011

#### Effects Of Large Cp Phases On The Proton Lifetime In Supersymmetric Unification, Tarek Ibrahim, Pran Nath

##### Pran Nath

The effects of large CP violating phases arising from the soft SUSY breaking parameters on the proton lifetime are investigated in supersymmetric grand unified models. It is found that the CP violating phases can reduce as well as enhance the proton lifetime depending on the part of the parameter space one is in. Modifications of the proton lifetime by as much as a factor of 2 due to the effects of the CP violating phases are seen. The largest effects arise for the lightest sparticle spectrum in the dressing loop integrals and the effects decrease with the increasing scale of ...

Cp Violation Effects On $B^0_{S,D}\To \It L^+\It L^-$ In Supersymmetry At Large $\Tan\Beta$, Tarek Ibrahim, Pran Nath Feb 2011

#### Cp Violation Effects On $B^0_{S,D}\To \It L^+\It L^-$ In Supersymmetry At Large $\Tan\Beta$, Tarek Ibrahim, Pran Nath

##### Pran Nath

An analytic analysis of the CP violating effects arising from the soft SUSY breaking parameters on the decays $B^0_{s,d}\to \it l^+\it l^-$ at large $\tan\beta$ is given. It is found that the phases have a strong effect on the branching ratio and in some regions of the parameter space they can lead to a variation of the branching ratio by as much as 1-2 orders of magnitude. These results have important implications for the discovery of the $B^0_{s}\to \mu^+\mu^-$ signal in RUNII of the Tevatron and further on how the ...

Effects Of Extra Space-Time Dimensions On The Fermi Constant, Pran Nath, Masahiro Yamaguchi Feb 2011

#### Effects Of Extra Space-Time Dimensions On The Fermi Constant, Pran Nath, Masahiro Yamaguchi

##### Pran Nath

Effects of Kaluza-Klein excitations associated with extra dimensions with large radius compactifications on the Fermi constant are explored. It is shown that the current precision determinations of the Fermi constant, of the fine structure constant, and of the W and Z mass put stringent constraints on the compactification radius. The analysis excludes one extra space time dimension below $\sim 1.6$ TeV, and excludes 2, 3 and 4 extra space dimensions opening simultaneously below $\sim$ 3.5 TeV, 5.7 TeV and 7.8 TeV at the $90% CL$. Implications of these results for future collider experiments are discussed.

Effects Of Kaluza-Klein Excitations On G_Μ-2, Pran Nath, Masahiro Yamaguchi Feb 2011

#### Effects Of Kaluza-Klein Excitations On G_Μ-2, Pran Nath, Masahiro Yamaguchi

##### Pran Nath

An analysis of the effects associated with the Kaluza-Klein excitations of the photon and of the W and Z bosons on g_{\mu}-2 for d number of extra dimensions with large radius compactifications is given. The Kaluza-Klein effects on g_{\mu}-2 are found to be very sensitive to the number of extra dimensions. For models where the quark-lepton generations live on the 4D wall, it is shown that when the constraints from the Kaluza-Klein corrections to the Fermi constant are included, the effects of the Kaluza-Klein excitations to g_{\mu}-2 become too small to be observable. A ...

Effects Of Cp Violation On Event Rates In The Direct Detection Of Dark Matter, Utpal Chattopadhyay, Tarek Ibrahim, Pran Nath Feb 2011

#### Effects Of Cp Violation On Event Rates In The Direct Detection Of Dark Matter, Utpal Chattopadhyay, Tarek Ibrahim, Pran Nath

##### Pran Nath

A full analytic analysis of the effects of CP violating phases on the event rates in the direct detection of dark matter in the scattering of neutralinos from nuclear targets is given. The analysis includes CP violating phases in softly broken supersymmetry in the framework of the minimal supersymmetric standard model (MSSM) when generational mixings are ignored. A numerical analysis shows that large CP violating phases including the constraints from the experimental limits on the neutron and the electron electric dipole moment (EDM) can produce substantial effects on the event rates in dark matter detectors.

Effects Of Large Cp Violating Phases On $G_{\M}-2$ In The Mssm, Tarek Ibrahim, Pran Nath Feb 2011

#### Effects Of Large Cp Violating Phases On $G_{\M}-2$ In The Mssm, Tarek Ibrahim, Pran Nath

##### Pran Nath

Effects of CP violation on the supersymmetric electro-weak correction to the anomalous magnetic moment of the muon are investigated with the most general allowed set of CP violating phases in MSSM. The analysis includes contributions from the chargino and the neutralino exchanges to the muon anomaly. The supersymmetric contributions depend only on specific combinations of CP phases. The independent set of such phases is classified. We analyse the effects of the phases under the EDM constraints and show that large CP violating phases can drastically affect the magnitude of the supersymmetric electro-weak contribution to $a_{\mu}$ and may even affect ...

#### Effective Lagrangian For $\Bar Q\Tilde Q'_I\Chi^+_J$, $\Bar Q\Tilde Q'_I\Chi^0_J$ Interactions And Fermionic Decays Of The Squarks With Cp Phases, Tarek Ibrahim, Pran Nath

##### Pran Nath

The one loop corrected effective Lagrangian for the quark-squark-chargino and quark-squark-neutralino interactions is computed. The effective Lagrangian takes into account the loop corrections arising from the exchange of the gluinos, charginos, neutralinos, W, Z, the charged Higgs, and the neutral Higgs. We further analyze the squark decays into charginos and neutralinos and discuss the effect of the loop corrections on them. The analysis takes into account CP phases in the soft parameters. It is found that the loop corrections to the stop decay widths into chargino and neutralinos can be as much as thirty percent or even larger. Further, the ...

Effects Of Gravitational Smearing On Predictions Of Supergravity Grand Unification, T. Dasgupta, P. Mamales, Pran Nath Feb 2011

#### Effects Of Gravitational Smearing On Predictions Of Supergravity Grand Unification, T. Dasgupta, P. Mamales, Pran Nath

##### Pran Nath

Limits on gravitational smearing from the dominant dimension 5 operator (with strength characterised by $cM/2M_{Planck}$) are obtained using the LEP data in supersymmetric SU(5) grand unification. Effects of c on the quasi infrared fixed point solutio ns of $m_b/m_{\tau}$ unification are also analysed. It is found that $c>0$ softens and $c<0$ stiffens the fixed point constraint. The effect of c on the upper bound of the Higgs triplet mass is analysed and the existence of a scaling induced by c is discussed. Tests for the existence of gravitational smearing are discussed.

Effective Lagrangian For The $\Chi^+_I\Chi_J^0h^-$ Interaction In The Minimal Supersymmetric Standard Model And Charged Higgs Decays, Tarek Ibrahim, Pran Nath, Anastasios Psinas Feb 2011

#### Effective Lagrangian For The $\Chi^+_I\Chi_J^0h^-$ Interaction In The Minimal Supersymmetric Standard Model And Charged Higgs Decays, Tarek Ibrahim, Pran Nath, Anastasios Psinas

We extend previous analyses of the supersymmetric loop correction to the charged Higgs couplings to include the coupling $H^{\pm}\chi^{\mp}\chi^0$. The analysis completes the previous analyses where similar corrections were computed for $H^+\bar t b$ ($H^-t\bar b$), and for $H^+\tau^- \bar\nu_{\tau}$ ($H^- \tau^+ \nu_{\tau}$) couplings within the minimal supersymmetric standard model. The effective one loop Lagrangian is then applied to the computation of the charged Higgs decays. The sizes of the supersymmetric loop correction on branching ratios of the charged Higgs $H^+(H^-)$ into the decay modes $t\bar ... Electric Dipole Moments And Polarizability In The Quark-Diquark Model Of The Neutron, Y. N. Srivastava, A. Widom, J. Swain, O. Panella Feb 2011 #### Electric Dipole Moments And Polarizability In The Quark-Diquark Model Of The Neutron, Y. N. Srivastava, A. Widom, J. Swain, O. Panella ##### John Swain For a bound state internal wave function respecting parity symmetry, it can be rigorously argued that the mean electric dipole moment must be strictly zero. Thus, both the neutron, viewed as a bound state of three quarks, and the water molecule, viewed as a bound state of ten electrons two protons and an oxygen nucleus, both have zero mean electric dipole moments. Yet, the water molecule is said to have a nonzero dipole moment strength$d=e\Lambda $with$\Lambda_{H_2O} \approx 0.385\ \dot{A}$. The neutron may also be said to have an electric dipole moment strength with ... Effects Of Anomalous Charged Current Dipole Moments Of The Tau On The Decay$\Tau^-\To\Nu_\Tau\Pi^-\Pi^0$, Maria-Teresa Dova, Pablo Lacentre, John Swain, Lucas Taylor Feb 2011 #### Effects Of Anomalous Charged Current Dipole Moments Of The Tau On The Decay$\Tau^-\To\Nu_\Tau\Pi^-\Pi^0$, Maria-Teresa Dova, Pablo Lacentre, John Swain, Lucas Taylor ##### John Swain We analyse the process$\tau^-\to\nu_\tau\pi^-\pi^0$allowing for anomalous weak charged current magnetic and electric dipole moment interactions and determine the effects on the differential and total decay rates. Using recent experimental data we determine the following values for the anomalous magnetic and electric dipole moment parameters, respectively:$\kappa = 0.16 \pm 0.08; and |\tilde\kappa| = 0.88^{+0.25}_{-0.35}.$Echoes Of The Fifth Dimension?, Luis A. Anchordoqui, Thomas P. Mccauley, Stephen Reucroft, John Swain Feb 2011 #### Echoes Of The Fifth Dimension?, Luis A. Anchordoqui, Thomas P. Mccauley, Stephen Reucroft, John Swain ##### John Swain In this article we examine the question of whether the highest energy cosmic ray primaries could be ultra relativistic magnetic monopoles. The analysis is performed within the framework of large compact dimensions and TeV scale quantum gravity. Our study indicates that while this hypothesis must be regarded as highly speculative it cannot be ruled out with present data. Effect Of The 3k Background Radiation On Ultrahigh Energy Cosmic Rays, L. A. Anchordoqui, M. T. Dova, L. N. Epele, J. D. Swain Feb 2011 #### Effect Of The 3k Background Radiation On Ultrahigh Energy Cosmic Rays, L. A. Anchordoqui, M. T. Dova, L. N. Epele, J. D. Swain ##### John Swain In this work we re-examine the opacity of the cosmic background radiation to the propagation of extremely high energy cosmic rays. We use the continuous energy loss approximation to provide spectral modification factors for several hypothesized cosmic ray sources. Earlier problems with this approximation are resolved including the effects of resonances other than the$\Delta$. Dijet Signals For Low Mass Strings At The Lhc, Luis A. Anchordoqui, Haim Goldberg, Dieter Lüst, Satoshi Nawata, Stephan Stieberger, Tomasz T. Taylor Feb 2011 #### Dijet Signals For Low Mass Strings At The Lhc, Luis A. Anchordoqui, Haim Goldberg, Dieter Lüst, Satoshi Nawata, Stephan Stieberger, Tomasz T. Taylor ##### Haim Goldberg We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we discuss possible signals of string physics at the Large Hadron Collider (LHC). In such D-brane constructions, the dominant contributions to full-fledged string amplitudes for all the common QCD parton subprocesses leading to dijets are completely independent of the details of compactification, and can be evaluated in ... Electron Neutrino Sources From The Core Of The Earth, A. Widom, E. Sassaroli, Y. N. Srivastava Feb 2011 #### Electron Neutrino Sources From The Core Of The Earth, A. Widom, E. Sassaroli, Y. N. Srivastava ##### Allan Widom The physical interpretation of extensive measurements of electron neutrinos (in laboratories located on or somewhat below the Earth's surface) often require geophysical notions concerning the possible neutrino sources. Here, we discuss the notion that the Earth's core is a substantial source of low energy electron neutrinos. Dispersive Techniques For$\Alpha_S$,$R_{Had}$And Instability Of The Perturbative Vacuum, Y. Srivastava, S. Pacetti, G. Pancheri, A. Widom Feb 2011 #### Dispersive Techniques For$\Alpha_S$,$R_{Had}$And Instability Of The Perturbative Vacuum, Y. Srivastava, S. Pacetti, G. Pancheri, A. Widom ##### Allan Widom Recent dispersive techniques developed by us are applied to discuss three problems: 1. A long standing discrepan-cy between the measurements of$R(s)$for$\sqrt{s} = (5\div 7.5)GeV$by Crystal Ball and MARK I has been analyzed and its consequences analyzed for the number of contributing quarks. 2. Noting that the perturbative$\alpha_s$has the wrong analyticity, analytic models consistent with asymptotic freedom (AF) and confinement have been constructed and applied to discuss$\tau$decay. 3. It is shown that AF leads to a wrong sign for$\im\big(\alpha(s)\big)\$ which signals an instability of ...

Electric Field Effects And The Experimental Value Of The Muon G-2 Anomaly, A. Widom, Y. N. Srivastava Feb 2011

#### Electric Field Effects And The Experimental Value Of The Muon G-2 Anomaly, A. Widom, Y. N. Srivastava

##### Allan Widom

The electric field corrections to the recently measured muon magnetic moment g-2 anomaly are considered from both the classical (BMT) and the quantum mechanical (Dirac) viewpoints. In both views, we prove that the electric field inducing the horizontal betatron tune does not renormalize the anomaly frequency. With this result kept in mind, the experimental muon magnetic moment anomaly is in closer agreement with standard model predictions than has been previously reported.

Decay Widths Of Lowest Massive Regge Excitations Of Open Strings, Luis A. Anchordoqui, Haim Goldberg, Tomasz R. Taylor Jan 2011

#### Decay Widths Of Lowest Massive Regge Excitations Of Open Strings, Luis A. Anchordoqui, Haim Goldberg, Tomasz R. Taylor

##### Tomasz Taylor

With the advent of the LHC there is widespread interest in the discovery potential for physics beyond the standard model. In TeV-scale open string theory, the new physics can be manifest in the excitation and decay of new resonant structures, corresponding to Regge recurrences of standard model particles. An essential input for the prediction of invariant mass spectra of the decay products (which could serve to identify the resonance as a string excitation) are the partial and total widths of the decay products. We present a parameter-free calculation of these widths for the first Regge recurrence of the SU(3 ...

Jan 2011

#### Constraints On The Tau Neutrino Mass And Mixing From Precise Measurements Of Tau Decay Rates, J. Swain, L. Taylor

##### John Swain

We have derived constraints on the tau neutrino mass and fourth generation mixing from an analysis of the partial widths of tau lepton decays, in particular: τ¯→e¯ν⁻eντ, τ¯→μ¯ν⁻μντ, τ →π¯ντ, and τ →K¯ντ. We present predictions for the tau decay widths, allowing for a non-zero tau neutrino mass, mντ, and for mixing with a neutrino of mass mνL > MZ/2, which is parametrised using a Cabibbo-like mixing angle, θL. By comparison of these theoretical predictions with the experimental measurements, we obtain the following bounds at the 90% confidence level: mντ < 42 MeV ...

Anomalous Charged Current Couplings Of The Tau And Implications For Tau Compositeness And Two-Higgs Doublet Models, Maria-Teresa Dova, John Swain, Lucas Taylor Jan 2011

#### Anomalous Charged Current Couplings Of The Tau And Implications For Tau Compositeness And Two-Higgs Doublet Models, Maria-Teresa Dova, John Swain, Lucas Taylor

##### John Swain

The leptonic branching fractions of the tau lepton are sensitive to anomalous charged current interactions. We use recent experimental measurements to determine the weak charged current magnetic and electric dipole moments and the Michel parameter with unprecedented precision. These results are then used to constrain the tau compositeness scale and the allowed parameter space for Higgs doublet models.

Constraints On Anomalous Charged Current Couplings, Tau Neutrino Mass And Fourth Generation Mixing From Tau Leptonic Branching Fractions, Maria Teresa Dova, John Swain, Lucas Taylor Jan 2011

#### Constraints On Anomalous Charged Current Couplings, Tau Neutrino Mass And Fourth Generation Mixing From Tau Leptonic Branching Fractions, Maria Teresa Dova, John Swain, Lucas Taylor

##### John Swain

We use recent experimental measurements of tau branching fractions to determine the weak charged current magnetic and electric dipole moments of the tau and the Michel parameter η with unprecedented precision. These results are then used to constrain the tau compositeness scale and the allowed parameter space for Higgs doublet models. We also present new constraints on the mass of the tau neutrino and its mixing with a fourth generation neutrino.

Dark Matter Prospects In Deflected Mirage Mediation, Michael Holmes, Brent T. Nelson Jan 2011

#### Dark Matter Prospects In Deflected Mirage Mediation, Michael Holmes, Brent T. Nelson

##### Brent Nelson

The recently introduced detected mirage mediation (DMM) model is a string-motivated paradigm in which all three of the major supersymmetry-breaking transmission mechanisms are operative. We begin a systematic exploration of the parameter space of this rich model context, paying special attention to the pattern of gaugino masses which arise. In this work we focus on the dark matter phenomenology of the DMM model as such signals are the least influenced by the model-dependent scalar masses. We find that a large portion of the parameter space in which the three mediation mechanisms have a similar effective mass scale of 1 TeV ...

Black Hole Chromosphere At The Cern Lhc, Luis Anchordoqui, Haim Goldberg Jan 2011

#### Black Hole Chromosphere At The Cern Lhc, Luis Anchordoqui, Haim Goldberg

##### Haim Goldberg

If the scale of quantum gravity is near a TeV, black holes will be copiously produced at the LHC. In this work we study the main properties of the light descendants of these black holes. We show that the emitted partons are closely spaced outside the horizon, and hence they do not fragment into hadrons in vacuum but more likely into a kind of quark-gluon plasma. Consequently, the thermal emission occurs far from the horizon, at a temperature characteristic of the QCD scale. We analyze the energy spectrum of the particles emerging from the "chromosphere", and find that the hard ...

Constraints On Unparticle Physics From Solar And Kamland Neutrinos, Luis Anchordoqui, Haim Goldberg Jan 2011

#### Constraints On Unparticle Physics From Solar And Kamland Neutrinos, Luis Anchordoqui, Haim Goldberg

##### Haim Goldberg

Interest has been directed recently towards low energy implications of a non-trivial conformal sector of an effective field theory with an IR fixed point (ΛU), manifest in terms of "unparticles" with bizarre properties. We re-examine the implications of the limits on decay lifetimes of solar neutrinos for unparticle interactions. We study in detail the fundamental parameter space (ΛU,M) and derive bounds on the energy scale M characterizing the new physics. We work strictly within the framework where conformal invariance holds down to low energies. We first assume that couplings of the unparticle sector to the Higgs field are suppressed ...

Cosmology From String Theory, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Carlos Nuñez Jan 2011

#### Cosmology From String Theory, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Carlos Nuñez

##### Haim Goldberg

We explore the cosmological content of Salam-Sezgin six dimensional supergravity, and find a solution to the field equations in qualitative agreement with observation of distant supernovae, primordial nucleosynthesis abundances, and recent measurements of the cosmic microwave background. The carrier of the acceleration in the present de Sitter epoch is a quintessence field slowly rolling down its exponential potential. Intrinsic to this model is a second modulus which is automatically stabilized and acts as a source of cold dark matter, with a mass proportional to an exponential function of the quintessence field (hence realizing VAMP models within a String context). However ...

Decay Widths Of Lowest Massive Regge Excitations Of Open Strings, Luis A. Anchordoqui, Haim Goldberg, Tomasz R. Taylor Jan 2011

#### Decay Widths Of Lowest Massive Regge Excitations Of Open Strings, Luis A. Anchordoqui, Haim Goldberg, Tomasz R. Taylor

##### Haim Goldberg

With the advent of the LHC there is widespread interest in the discovery potential for physics beyond the standard model. In TeV-scale open string theory, the new physics can be manifest in the excitation and decay of new resonant structures, corresponding to Regge recurrences of standard model particles. An essential input for the prediction of invariant mass spectra of the decay products (which could serve to identify the resonance as a string excitation) are the partial and total widths of the decay products. We present a parameter-free calculation of these widths for the first Regge recurrence of the SU(3 ...

Compact Lattice Qed And The Coulomb Potential, Y. N. Srivastava, A. Widom, M. H. Friedman, O. Panella Jan 2011

#### Compact Lattice Qed And The Coulomb Potential, Y. N. Srivastava, A. Widom, M. H. Friedman, O. Panella

##### Allan Widom

The potential energy of a static charge distribution on a lattice is rigorously computed in the standard compact quantum electrodynamic model. The method used follows closely that of Weyl for ordinary quantum electrodynamics in continuous space-time. The potential energy of the static charge distribution is independent of temperature and can be calculated from the lattice version of Poisson’s equation. It is the usual Coulomb potential.

Breakdown Of The Kln Theorem For Charged Particles In Condensed Matter, Y. N. Srivastava, A. Widom Jan 2011

#### Breakdown Of The Kln Theorem For Charged Particles In Condensed Matter, Y. N. Srivastava, A. Widom

##### Allan Widom

The Kinoshita-Lee-Nauenberg (KLN) theorem describes the fact that inclusive electromagnetic and weak production processes in the vacuum do not contain singularities in the ultra-relativistic limit of zero mass. When these production processes occur in condensed matter, the KLN theorem fails. One consequence of this failure is that precision lifetime determinations of stopped muons will depend on the nature of the surrounding material.