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Full-Text Articles in Physics

Calculation Of Physical Processes At The Lhc, Usama Adnan Al-Binni Dec 2011

Calculation Of Physical Processes At The Lhc, Usama Adnan Al-Binni

Doctoral Dissertations

With the start of the age of the Large Hadron Collider (LHC) two challenges face theoreticians and computational physicists. The first is about understanding theories beyond the Standard Model and producing verifiable predictions that can be tested against what the LHC and subsequent machines would produce. The second is to improve computational methods so that the new experimental precision is matched by a theoretical one. But this improvement is also crucial for the detection of potential deviations from Standard Model predictions and possibly also finding the elusive Higgs. This work tries to address problems in both areas. In the first …


Search For Contact Interactions With Dimuons At The Atlas Detector, Emily Thompson Sep 2011

Search For Contact Interactions With Dimuons At The Atlas Detector, Emily Thompson

Open Access Dissertations

The Standard Model has been very successful over the last few decades in its agreement with experimental evidence; however there are some remaining puzzles in our understanding of the Universe which have yet to be solved. Even if the Higgs boson and Super Symmetry are discovered, questions still arise, such as why Nature is primarily made of matter when antimatter should have been produced in equal amounts at the beginning of the Universe, why the fundamental particles have the mass hierarchy that they do, what the nature of dark matter is, or whether or not quarks and leptons are themselves …


Analysis Of Prominent Decay Modes For The Higgs Boson At The Lhc, Matthew Parenti May 2011

Analysis Of Prominent Decay Modes For The Higgs Boson At The Lhc, Matthew Parenti

Physics

No abstract provided.


Direct Photons As Probes Of Low Mass Strings At The Lhc, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Tomasz Taylor Feb 2011

Direct Photons As Probes Of Low Mass Strings At The Lhc, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Tomasz Taylor

Tomasz Taylor

The LHC program will include the identification of events with single prompt high-k_\perp photons as probes of new physics. We show that this channel is uniquely suited to search for experimental evidence of TeV-scale open string theory. At the parton level, we analyze single photon production in gluon fusion, gg \to \gamma g, with open string states propagating in intermediate channels. If the photon mixes with the gauge boson of the baryon number, which is a common feature of D-brane quivers, the amplitude appears already at the string disk level. It is completely determined by the mixing parameter (which is …


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 Photons As Probes Of Low Mass Strings At The Lhc, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Tomasz Taylor Feb 2011

Direct Photons As Probes Of Low Mass Strings At The Lhc, Luis Anchordoqui, Haim Goldberg, Satoshi Nawata, Tomasz Taylor

Haim Goldberg

The LHC program will include the identification of events with single prompt high-k_\perp photons as probes of new physics. We show that this channel is uniquely suited to search for experimental evidence of TeV-scale open string theory. At the parton level, we analyze single photon production in gluon fusion, gg \to \gamma g, with open string states propagating in intermediate channels. If the photon mixes with the gauge boson of the baryon number, which is a common feature of D-brane quivers, the amplitude appears already at the string disk level. It is completely determined by the mixing parameter (which is …


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 …


Dark Matter As A Guide Toward A Light Gluino At The Lhc, Daniel Feldman, Gordon Kane, Ran Lu, Brent T. Nelson Jan 2011

Dark Matter As A Guide Toward A Light Gluino At The Lhc, Daniel Feldman, Gordon Kane, Ran Lu, Brent T. Nelson

Brent Nelson

Motivated by specific connections to dark matter signatures, we study the prospects of observing the presence of a relatively light gluino whose mass is in the range ~ (500 − 900) GeV with a wino-like lightest supersymmetric particle with mass in the range of ~ (170 − 210) GeV. The light gaugino spectra studied here is generally different from other models, and in particular those with a wino dominated LSP, in that here the gluinos can be significantly lighter. The positron excess reported by the PAMELA satellite data is accounted for by annihilations of the wino LSP and their relic …


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 …


Decoding The Mechanism For The Origin Of Dark Matter In The Early Universe Using Lhc Data, Daniel Feldman, Zuowei Liu, Pran Nath Jan 2011

Decoding The Mechanism For The Origin Of Dark Matter In The Early Universe Using Lhc Data, Daniel Feldman, Zuowei Liu, Pran Nath

Pran Nath

It is shown that LHC data can allow one to decode the mechanism by which dark matter is generated in the early universe in supersymmetric theories. We focus on two of the major mechanisms for such generation of dark matter which are known to be the Stau Coannihilation (Stau-Co) where the neutralino is typically Bino like and annihilation on the Hyperbolic Branch (HB) where the neutralino has a significant Higgsino component. An investigation of how one may discriminate between the Stau-Co region and the HB region using LHC data is given for the mSUGRA model. The analysis utilizes several signatures …


Connecting The Direct Detection Of Dark Matter With Observation Of Sparticles At The Lhc, Daniel Feldman, Zuowei Liu, Pran Nath Jan 2011

Connecting The Direct Detection Of Dark Matter With Observation Of Sparticles At The Lhc, Daniel Feldman, Zuowei Liu, Pran Nath

Pran Nath

An analysis is given connecting event rates for the direct detection of neutralino dark matter with the possible signatures of supersymmetry at the LHC. It is shown that if an effect is seen in the direct detection experiments at a level of O(10⁻⁴⁴) cm² for the neutralino-proton cross section, then within the mSUGRA model the next heavier particle above the neutralino is either a stau, a chargino, or a CP odd/CP even (A/H) Higgs boson. Further, the collider analysis shows that models with a neutralino-proton cross section at the level of (1 − 5) × 10⁻⁴⁴ cm² could be probed …