U. Haisch - Oxford University

U. Haisch
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Name
U. Haisch
Affiliation
Oxford University
City
Oxford
Country
United States

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High Energy Physics - Phenomenology (50)
 
High Energy Physics - Experiment (39)
 
Cosmology and Nongalactic Astrophysics (3)
 
High Energy Physics - Lattice (2)
 
High Energy Physics - Theory (2)
 
High Energy Astrophysical Phenomena (1)
 
Nuclear Experiment (1)
 
Nuclear Theory (1)
 
Physics - Accelerator Physics (1)

Publications Authored By U. Haisch

Weakly-coupled TeV-scale particles may mediate the interactions between normal matter and dark matter. If so, the LHC would produce dark matter through these mediators, leading to the familiar "mono-X" search signatures, but the mediators would also produce signals without missing momentum via the same vertices involved in their production. This document from the LHC Dark Matter Working Group suggests how to compare searches for these two types of signals in case of vector and axial-vector mediators, based on a workshop that took place on September 19/20, 2016 and subsequent discussions. Read More

We study a new class of renormalisable simplified models for dark matter searches at the LHC that are based on two Higgs doublet models with an additional pseudoscalar mediator. In contrast to the spin-0 simplified models employed in analyses of Run I data these models are self-consistent, unitary and bounds from Higgs physics typically pose no constraints. Predictions for various missing transverse energy ($E_{T, \rm miss}$) searches are discussed and the reach of the 13 TeV LHC is explored. Read More

In the framework of spin-0 $s$-channel simplified models, we explore the possibility of assessing the structure of dark matter interactions through the associate production of dark matter and $t\bar{t}$ pairs. To this purpose, final states with two leptons are considered and the kinematic properties of the dilepton system is studied. We develop a realistic analysis strategy and provide a detailed evaluation of the achievable sensitivity for the dark matter signal assuming integrated luminosities of $300 \, {\rm fb}^{-1}$ and $3 \, {\rm ab}^{-1}$ at the 14 TeV LHC. Read More

We examine the constraints on the trilinear Higgs coupling $\lambda$ that originate from associated ($Vh$) and vector boson fusion (VBF) Higgs production in $pp$ collisions in the context of the Standard Model effective field theory. The 1-loop contributions to $pp \to V h$ and $pp \to jj h$ that stem from insertions of the dimension-6 operator $O_6 = - \lambda \left (H^\dagger H \right )^3$ are calculated and combined with the ${\cal O} (\lambda)$ corrections to the partial decay widths of the Higgs boson. Employing next-to-next-to-leading order QCD predictions, we analyse the sensitivity of current and forthcoming measurements of the signal strengths in $Vh$ and VBF Higgs production to changes in $\lambda$. Read More

This White Paper is an input to the ongoing discussion about the extension and refinement of simplified Dark Matter (DM) models. Based on two concrete examples, we show how existing simplified DM models (SDMM) can be extended to provide a more accurate and comprehensive framework to interpret and characterise collider searches. In the first example we extend the canonical SDMM with a scalar mediator to include mixing with the Higgs boson. Read More

In the framework of the Standard Model effective field theory, we examine the indirect constraints on the trilinear Higgs coupling $\lambda$ that arise from Higgs production in gluon-gluon-fusion and diphoton Higgs decays. We calculate 2-loop contributions to the $gg \to h$ and $h \to \gamma \gamma$ amplitudes that are affected by modifications of the trilinear Higgs-boson vertex. This calculation involves both the computation of anomalous dimensions and finite matching corrections. Read More

We propose a novel strategy to constrain the bottom and charm Yukawa couplings by exploiting LHC measurements of transverse momentum distributions in Higgs production. Our method does not rely on the reconstruction of exclusive final states or heavy-flavour tagging. Compared to other proposals it leads to an enhanced sensitivity to the Yukawa couplings due to distortions of the differential Higgs spectra from emissions which either probe quark loops or are associated to quark-initiated production. Read More

Natural realisations of supersymmetry require light stops ${\tilde t}_1$, making them a prime target of LHC searches for physics beyond the Standard Model. Depending on the kinematic region, the main search channels are ${\tilde t_1}\to t \tilde \chi^0_1$, ${\tilde t_1}\to W b \tilde \chi^0_1$ and ${\tilde t_1}\to c \tilde \chi^0_1$. We first examine the interplay of these decay modes with ${\tilde c_1}\to c \tilde \chi^0_1$ in a model-independent fashion, revealing the existence of large regions in parameter space which are excluded for any ${\tilde t_1}\to c \tilde \chi^0_1$ branching ratio. Read More

The potential sensitivity to isospin-breaking effects makes LHC searches for mono-W signatures promising probes of the coupling structure between the Standard Model and dark matter. It has been shown, however, that the strong sensitivity of the mono-W channel to the relative magnitude and sign of the up-type and down-type quark couplings to dark matter is an artefact of unitarity violation. We provide three different solutions to this mono-W problem in the context of spin-1 simplified models and briefly discuss the impact that our findings have on the prospects of mono-W searches at future LHC runs. Read More

We study the phenomenology of light spin-0 particles and stress that they can be efficiently searched for at the LHCb experiment in the form of dimuon resonances. Given the large production cross sections in the forward rapidity region together with the efficient triggering and excellent mass resolution, it is argued that LHCb can provide unique sensitivity to such states. We illustrate our proposal using the recent measurement of Upsilon production by LHCb, emphasising the importance of mixing effects in the bottomonium resonance region. Read More

A personal account of possible implications of recent heavy flavour measurements is given. Read More

2015Jul
Authors: Daniel Abercrombie, Nural Akchurin, Ece Akilli, Juan Alcaraz Maestre, Brandon Allen, Barbara Alvarez Gonzalez, Jeremy Andrea, Alexandre Arbey, Georges Azuelos, Patrizia Azzi, Mihailo Backović, Yang Bai, Swagato Banerjee, James Beacham, Alexander Belyaev, Antonio Boveia, Amelia Jean Brennan, Oliver Buchmueller, Matthew R. Buckley, Giorgio Busoni, Michael Buttignol, Giacomo Cacciapaglia, Regina Caputo, Linda Carpenter, Nuno Filipe Castro, Guillelmo Gomez Ceballos, Yangyang Cheng, John Paul Chou, Arely Cortes Gonzalez, Chris Cowden, Francesco D'Eramo, Annapaola De Cosa, Michele De Gruttola, Albert De Roeck, Andrea De Simone, Aldo Deandrea, Zeynep Demiragli, Anthony DiFranzo, Caterina Doglioni, Tristan du Pree, Robin Erbacher, Johannes Erdmann, Cora Fischer, Henning Flaecher, Patrick J. Fox, Benjamin Fuks, Marie-Helene Genest, Bhawna Gomber, Andreas Goudelis, Johanna Gramling, John Gunion, Kristian Hahn, Ulrich Haisch, Roni Harnik, Philip C. Harris, Kerstin Hoepfner, Siew Yan Hoh, Dylan George Hsu, Shih-Chieh Hsu, Yutaro Iiyama, Valerio Ippolito, Thomas Jacques, Xiangyang Ju, Felix Kahlhoefer, Alexis Kalogeropoulos, Laser Seymour Kaplan, Lashkar Kashif, Valentin V. Khoze, Raman Khurana, Khristian Kotov, Dmytro Kovalskyi, Suchita Kulkarni, Shuichi Kunori, Viktor Kutzner, Hyun Min Lee, Sung-Won Lee, Seng Pei Liew, Tongyan Lin, Steven Lowette, Romain Madar, Sarah Malik, Fabio Maltoni, Mario Martinez Perez, Olivier Mattelaer, Kentarou Mawatari, Christopher McCabe, Théo Megy, Enrico Morgante, Stephen Mrenna, Siddharth M. Narayanan, Andy Nelson, Sérgio F. Novaes, Klaas Ole Padeken, Priscilla Pani, Michele Papucci, Manfred Paulini, Christoph Paus, Jacopo Pazzini, Björn Penning, Michael E. Peskin, Deborah Pinna, Massimiliano Procura, Shamona F. Qazi, Davide Racco, Emanuele Re, Antonio Riotto, Thomas G. Rizzo, Rainer Roehrig, David Salek, Arturo Sanchez Pineda, Subir Sarkar, Alexander Schmidt, Steven Randolph Schramm, William Shepherd, Gurpreet Singh, Livia Soffi, Norraphat Srimanobhas, Kevin Sung, Tim M. P. Tait, Timothee Theveneaux-Pelzer, Marc Thomas, Mia Tosi, Daniele Trocino, Sonaina Undleeb, Alessandro Vichi, Fuquan Wang, Lian-Tao Wang, Ren-Jie Wang, Nikola Whallon, Steven Worm, Mengqing Wu, Sau Lan Wu, Hongtao Yang, Yong Yang, Shin-Shan Yu, Bryan Zaldivar, Marco Zanetti, Zhiqing Zhang, Alberto Zucchetta

This document is the final report of the ATLAS-CMS Dark Matter Forum, a forum organized by the ATLAS and CMS collaborations with the participation of experts on theories of Dark Matter, to select a minimal basis set of dark matter simplified models that should support the design of the early LHC Run-2 searches. A prioritized, compact set of benchmark models is proposed, accompanied by studies of the parameter space of these models and a repository of generator implementations. This report also addresses how to apply the Effective Field Theory formalism for collider searches and present the results of such interpretations. Read More

2015Jun
Authors: Jalal Abdallah, Henrique Araujo, Alexandre Arbey, Adi Ashkenazi, Alexander Belyaev, Joshua Berger, Celine Boehm, Antonio Boveia, Amelia Brennan, Jim Brooke, Oliver Buchmueller, Matthew Buckley, Giorgio Busoni, Lorenzo Calibbi, Sushil Chauhan, Nadir Daci, Gavin Davies, Isabelle De Bruyn, Paul De Jong, Albert De Roeck, Kees de Vries, Daniele Del Re, Andrea De Simone, Andrea Di Simone, Caterina Doglioni, Matthew Dolan, Herbi K. Dreiner, John Ellis, Sarah Eno, Erez Etzion, Malcolm Fairbairn, Brian Feldstein, Henning Flaecher, Eric Feng, Patrick Fox, Marie-Hélène Genest, Loukas Gouskos, Johanna Gramling, Ulrich Haisch, Roni Harnik, Anthony Hibbs, Siewyan Hoh, Walter Hopkins, Valerio Ippolito, Thomas Jacques, Felix Kahlhoefer, Valentin V. Khoze, Russell Kirk, Andreas Korn, Khristian Kotov, Shuichi Kunori, Greg Landsberg, Sebastian Liem, Tongyan Lin, Steven Lowette, Robyn Lucas, Luca Malgeri, Sarah Malik, Christopher McCabe, Alaettin Serhan Mete, Enrico Morgante, Stephen Mrenna, Yu Nakahama, Dave Newbold, Karl Nordstrom, Priscilla Pani, Michele Papucci, Sophio Pataraia, Bjoern Penning, Deborah Pinna, Giacomo Polesello, Davide Racco, Emanuele Re, Antonio Walter Riotto, Thomas Rizzo, David Salek, Subir Sarkar, Steven Schramm, Patrick Skubic, Oren Slone, Juri Smirnov, Yotam Soreq, Timothy Sumner, Tim M. P. Tait, Marc Thomas, Ian Tomalin, Christopher Tunnell, Alessandro Vichi, Tomer Volansky, Neal Weiner, Stephen M. West, Monika Wielers, Steven Worm, Itay Yavin, Bryan Zaldivar, Ning Zhou, Kathryn Zurek

This document outlines a set of simplified models for dark matter and its interactions with Standard Model particles. It is intended to summarize the main characteristics that these simplified models have when applied to dark matter searches at the LHC, and to provide a number of useful expressions for reference. The list of models includes both s-channel and t-channel scenarios. Read More

I briefly discuss recent theoretical advances in the description of mono-X signals at the LHC. Read More

The LHCb collaboration has recently performed a first measurement of the angular production asymmetry in the distribution of beauty quarks and anti-quarks at a hadron collider. We calculate the corresponding standard model prediction for this asymmetry at fixed-order in perturbation theory. Our results show good agreement with the data, which is provided differentially for three bins in the invariant mass of the $b \bar b$ system. Read More

We consider the three CP-conserving dimension-6 operators that encode the leading new-physics effects in the triple gauge couplings. The contributions to the standard-model electromagnetic dipole and semi-leptonic vector and axial-vector interactions that arise from the insertions of these operators are calculated. We show that radiative and rare $B$-meson decays provide, under certain assumptions, constraints on two out of the three anomalous couplings that are competitive with the restrictions obtained from LEP II, Tevatron and LHC data. Read More

Weak radiative decays of the B mesons belong to the most important flavor changing processes that provide constraints on physics at the TeV scale. In the derivation of such constraints, accurate standard model predictions for the inclusive branching ratios play a crucial role. In the current Letter we present an update of these predictions, incorporating all our results for the O(alpha_s^2) and lower-order perturbative corrections that have been calculated after 2006. Read More

Stringent limits on the interactions between dark matter (DM) and the standard model can be set by studying how initial-state or final-state particles recoil against missing transverse energy (MET). In this work, we improve, extend and correct LHC constraints on the interactions between DM and top quarks that are mediated by the exchange of spin-0 s-channel resonances. A comparison of the LHC run-1 sensitivity of the two main search channels is presented, which shows that mono-jet searches are typically more restrictive than the MET + tbar t searches. Read More

Collider searches for energetic particles recoiling against missing transverse energy allow to place strong bounds on the interactions between dark matter (DM) and standard model particles. In this article we update and extend LHC constraints on effective dimension-7 operators involving DM and electroweak gauge bosons. A concise comparison of the sensitivity of the mono-photon, mono-W, mono-Z, mono-W/Z, invisible Higgs-boson decays in the vector boson fusion mode and the mono-jet channel is presented. Read More

While many interactions of dark matter (DM) with the standard model (SM) affect direct detection and LHC searches, there are only a few operators generating annihilation of DM into photons. All of these operators, except four of them, give rise to unsuppressed rates, rendering indirect detection superior to other search strategies. For two of the four effective interactions with velocity-suppressed annihilation cross sections, we identify a new type of loop effect which significantly enhances the associated direct detection rates. Read More

A discovery of flavour-changing Higgs-boson decays would constitute an undeniable signal of new physics. We derive model-independent constraints on the tch and tuh couplings that arise from the bounds on hadronic electric dipole moments. Comparisons of the present and future sensitivities with both the direct LHC constraints and the indirect limits from D-meson physics are also presented. Read More

Motivated by the recent measurement of the dimuon asymmetry by the D{\O} collaboration, which could be interpreted as an enhanced decay rate difference in the neutral $B_d$-meson system, we investigate the possible size of new-physics contributions to $\Delta \Gamma_d$. In particular, we perform model-independent studies of non-standard effects associated to the dimension-six current-current operators $(\bar{d} p)(\bar p^{\hspace{0.25mm}\prime} b)$ with $p,p^\prime= u,c$ as well as $(\bar{d}b) (\bar\tau\tau)$. Read More

The latest LHC mono-jet searches place stringent bounds on the pp -> chibar chi cross section of dark matter. Further properties such as the dark matter mass or the precise structure of the interactions between dark matter and the standard model can however not be determined in this manner. We point out that measurements of the azimuthal angle correlations between the two jets in 2 j + chibar chi events may be used to disentangle whether dark matter pair production proceeds dominantly through tree or loop diagrams. Read More

LHC searches for missing transverse energy in association with a jet allow to place strong bounds on the interactions between dark matter and quarks. In this article, we present an extension of the POWHEG BOX capable of calculating the underlying cross sections at the next-to-leading order level. This approach enables us to consistently include the effects of parton showering and to apply realistic experimental cuts. Read More

Discovering CP-violating effects in the Higgs sector would constitute an indisputable sign of physics beyond the Standard Model. We derive constraints on the CP-violating Higgs-boson couplings to top and bottom quarks as well as to tau leptons from low-energy bounds on electric dipole moments, resumming large logarithms when necessary. The present and future projections of the sensitivities and comparisons with the LHC constraints are provided. Read More

A global fit to the recent B->K*mu+mu- data shows indications for a large new-physics contribution to the Wilson coefficient of the semi-leptonic vector operator. In this article we consider a simple Z'-boson model of 3-3-1 type that can accommodate such an effect without violating any other constraint from quark-flavour physics. Implications for yet unobserved decay modes such as B->Xsnunubar and longstanding puzzles like B->piK are also discussed. Read More

Recently LHCb has announced a discrepancy of 3.7 sigma in one of the theoretically clean observables accessible through studies of angular correlations in B->K*mu+mu-. We point out that in the most minimal Z' setup that can address this anomaly there is a model-independent triple-correlation between new physics (NP) in B->K*mu+mu-, B_s-Bbar_s mixing, and non-unitarity of the quark-mixing matrix. Read More

2013Jun
Authors: Andreas S. Kronfeld1, Robert S. Tschirhart2, Usama Al-Binni, Wolfgang Altmannshofer, Charles Ankenbrandt, Kaladi Babu, Sunanda Banerjee, Matthew Bass, Brian Batell, David V. Baxter, Zurab Berezhiani, Marc Bergevin, Robert Bernstein, Sudeb Bhattacharya, Mary Bishai, Thomas Blum, S. Alex Bogacz, Stephen J. Brice, Joachim Brod, Alan Bross, Michael Buchoff, Thomas W. Burgess, Marcela Carena, Luis A. Castellanos, Subhasis Chattopadhyay, Mu-Chun Chen, Daniel Cherdack, Norman H. Christ, Tim Chupp, Vincenzo Cirigliano, Pilar Coloma, Christopher E. Coppola, Ramanath Cowsik, J. Allen Crabtree, André de Gouvêa, Jean-Pierre Delahaye, Dmitri Denisov, Patrick deNiverville, Ranjan Dharmapalan, Markus Diefenthaler, Alexander Dolgov, Georgi Dvali, Estia Eichten, Jürgen Engelfried, Phillip D. Ferguson, Tony Gabriel, Avraham Gal, Franz Gallmeier, Kenneth S. Ganezer, Susan Gardner, Douglas Glenzinski, Stephen Godfrey, Elena S. Golubeva, Stefania Gori, Van B. Graves, Geoffrey Greene, Cory L. Griffard, Ulrich Haisch, Thomas Handler, Brandon Hartfiel, Athanasios Hatzikoutelis, Ayman Hawari, Lawrence Heilbronn, James E. Hill, Patrick Huber, David E. Jaffe, Xiaodong Jiang, Christian Johnson, Yuri Kamyshkov, Daniel M. Kaplan, Boris Kerbikov, Brendan Kiburg, Harold G. Kirk, Andreas Klein, Kyle Knoepfel, Boris Kopeliovich, Vladimir Kopeliovich, Joachim Kopp, Wolfgang Korsch, Graham Kribs, Ronald Lipton, Chen-Yu Liu, Wolfgang Lorenzon, Zheng-Tian Lu, Naomi C. R. Makins, David McKeen, Geoffrey Mills, Michael Mocko, Rabindra Mohapatra, Nikolai V. Mokhov, Guenter Muhrer, Pieter Mumm, David Neuffer, Lev Okun, Mark A. Palmer, Robert Palmer, Robert W. Pattie Jr., David G. Phillips II, Kevin Pitts, Maxim Pospelov, Vitaly S. Pronskikh, Chris Quigg, Erik Ramberg, Amlan Ray, Paul E. Reimer, David G. Richards, Adam Ritz, Amit Roy, Arthur Ruggles, Robert Ryne, Utpal Sarkar, Andy Saunders, Yannis K. Semertzidis, Anatoly Serebrov, Hirohiko Shimizu, Robert Shrock, Arindam K. Sikdar, Pavel V. Snopok, William M. Snow, Aria Soha, Stefan Spanier, Sergei Striganov, Zhaowen Tang, Lawrence Townsend, Jon Urheim, Arkady Vainshtein, Richard Van de Water, Ruth S. Van de Water, Richard J. Van Kooten, Bernard Wehring, William C. Wester III, Lisa Whitehead, Robert J. Wilson, Elizabeth Worcester, Albert R. Young, Geralyn Zeller
Affiliations: 1Editors, 2Editors

Part 2 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". In this Part, we outline the particle-physics program that can be achieved with Project X, a staged superconducting linac for intensity-frontier particle physics. Topics include neutrino physics, kaon physics, muon physics, electric dipole moments, neutron-antineutron oscillations, new light particles, hadron structure, hadron spectroscopy, and lattice-QCD calculations. Read More

In large volume models reheating is driven by the decays of the volume modulus to the visible sector, while the decays to its axion partners result in dark radiation. In this article we discuss the impact of loop corrections on the only model-independent visible decay channel: the decay into Higgs pairs via a Giudice-Masiero term. Including such radiative effects leads to a more precise determination of the relative fraction of dark radiation, since by contrast all loop corrections to the volume axion decay mode are Planck suppressed. Read More

A brief review of theoretical aspects of new-physics searches in flavor physics is given. Special attention is thereby devoted to B_s mixing and the interplay of high- and low-p_T observations. Read More

The latest results from LHC searches for jets in association with missing transverse energy place strong bounds on the scattering cross section of dark matter. For the case of spin-dependent or momentum suppressed interactions these limits seem to be superior to the bounds from direct detection experiments. In this article, we show that loop contributions can significantly alter this conclusion and boost direct detection bounds, whenever they induce spin-independent interactions. Read More

Inspired by the latest results of ATLAS and CMS on the search for the standard model (SM) Higgs scalar, we discuss in this article the correlations between Higgs-boson properties, low-energy observables, such as B -> X_sgamma, B_s -> mu^+mu^-, and (g-2)_mu, and the dark matter (DM) relic density. We focus on the corners of the MSSM parameter space where the pp -> h -> gammagamma signal is enhanced due to the presence of a light stau state. In this region tan(beta), M_A, A_t, and mu take large values, and we find striking correlations between many of the considered observables. Read More

If only tree-level processes are included in the analysis, LHC monojet searches give weak constraints on the dark matter-proton scattering cross section arising from the exchange of a new heavy scalar or pseudoscalar mediator with Yukawa-like couplings to quarks. In this letter we calculate the constraints on these interactions from the CMS 5.0/fb and ATLAS 4. Read More

Improved limits as well as tentative claims for dark matter annihilation into gamma-ray lines have been presented recently. We study the direct detection cross section induced from dark matter annihilation into two photons in a model-independent fashion, assuming no additional couplings between dark matter and nuclei. We find a striking non-standard recoil spectrum due to different destructively interfering contributions to the dark matter nucleus scattering cross section. Read More

The status of possible new-physics signals in B_s,d-meson mixing and decay is reviewed. In particular, it is emphasized that the recent LHCb results, that find no evidence for a non-standard phase in B_s-barB_s mixing, make a consistent explanation of the D0 data on the like-sign dimuon charge asymmetry notoriously difficult. In order to clarify the inconclusive experimental situation, independent measurements of the semileptonic asymmetries are needed. Read More

2012Mar

Measurements of the Higgs-boson production cross section at the LHC are an important tool for studying electroweak symmetry breaking at the quantum level, since the main production mechanism gg-->h is loop-suppressed in the Standard Model (SM). Higgs production in extra-dimensional extensions of the SM is sensitive to the Kaluza-Klein (KK) excitations of the quarks, which can be exchanged as virtual particles in the loop. In the context of the minimal Randall-Sundrum (RS) model with bulk fields and a brane-localized Higgs sector, we derive closed analytical expressions for the gluon-gluon fusion process, finding that the effect of the infinite tower of virtual KK states can be described in terms of a simple function of the fundamental (5D) Yukawa matrices. Read More

2012Mar
Authors: G. Brooijmans, B. Gripaios, F. Moortgat, J. Santiago, P. Skands, D. Albornoz Vásquez, B. C. Allanach, A. Alloul, A. Arbey, A. Azatov, H. Baer, C. Balázs, A. Barr, L. Basso, M. Battaglia, P. Bechtle, G. Bélanger, A. Belyaev, K. Benslama, L. Bergström, A. Bharucha, C. Boehm, M. Bondarenko, O. Bondu, E. Boos, F. Boudjema, T. Bringmann, M. Brown, V. Bunichev, S. Calvet, M. Campanelli, A. Carmona, D. G. Cerdeño, M. Chala, R. S. Chivukula, D. Chowdhury, N. D. Christensen, M. Cirelli, S. Cox, K. Cranmer, J. Da Silva, T. Delahaye, A. De Roeck, A. Djouadi, E. Dobson, M. Dolan, F. Donato, G. Drieu La Rochelle, G. Duda, C. Duhr, B. Dumont, J. Edsjö, J. Ellis, C. Evoli, A. Falkowski, M. Felcini, B. Fuks, E. Gabrielli, D. Gaggero, S. Gascon-Shotkin, D. K. Ghosh, A. Giammanco, R. M. Godbole, P. Gondolo, T. Goto, D. Grasso, P. Gris, D. Guadagnoli, J. F. Gunion, U. Haisch, L. Hartgring, S. Heinemeyer, M. Hirsch, J. Hewett, A. Ismail, T. Jeltema, M. Kadastik, M. Kakizaki, K. Kannike, S. Khalil, J-L. Kneur, M. Krämer, S. Kraml, S. Kreiss, J. Lavalle, R. Leane, J. Lykken, L. Maccione, F. Mahmoudi, M. Mangano, S. P. Martin, D. Maurin, G. Moreau, S. Moretti, I. Moskalenko, G. Moultaka, M. Muhlleitner, I. Niessen, B. O'Leary, E. Orlando, P. Panci, G. Polesello, W. Porod, T. Porter, S. Profumo, H. Prosper, A. Pukhov, A. Racioppi, M. Raidal, M. Rausch de Traubenberg, A. Renaud, J. Reuter, T. G. Rizzo, T. Robens, A. Y. Rodríguez-Marrero, P. Salati, C. Savage, P. Scott, S. Sekmen, A. Semenov, C. -L. Shan, C. Shepherd-Themistocleous, E. H. Simmons, P. Slavich, C. Speckner, F. Staub, A. Strong, R. Taillet, F. S. Thomas, M. C. Thomas, I. Tomalin, M. Tytgat, M. Ughetto, L. Valéry, D. G. E. Walker, A. Weiler, S. M. West, C. D. White, A. J. Williams, A. Wingerter, C. Wymant, J. -H. Yu, C. -P. Yuan, D. Zerwas

We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC search results, as well as additional phenomenological studies. Read More

We point out that the discovery of a light Higgs boson in the \gamma\gamma, ZZ and WW decay channels at the LHC, with cross sections not far from the predictions of the Standard Model, would have important implications for the parameters of warped extra-dimension models. Due to loop effects of Kaluza-Klein particles, these models predict a significant reduction of the Higgs production cross section via gluon-gluon fusion, combined with an enhancement of the ratio Br(h->\gamma\gamma)/Br(h->ZZ). LHC measurements of these decays will probe Kaluza-Klein masses up to the 10 TeV range, exceeding by far the reach for direct production. Read More

Measurements performed at the Tevatron of both the like-sign dimuon charge asymmetry in B_d,s-meson samples and the mixing-induced CP asymmetry in B_s -> J/psi phi depart from their standard model (SM) predictions. This could be an indication for new CP phases in Delta B = 2 transitions, preferentially in B_s-Bbar_s mixing. The experimental situation, however, remained inconclusive, as it favored values of the element Gamma_12^s of the decay matrix in the B_s-meson system that are notably different from the SM expectation, suggesting the presence of new physics in the Delta B = 1 sector as well. Read More

A critical survey of the existing direct and indirect constraints on massive spin-one color octets is presented. Since such new degrees of freedom appear in any extension of the color gauge group to a product of at least two SU(3) factors, we keep our discussion as independent as possible from the underlying theory. In the framework of scenarios that involve flavor non-universal couplings, we show that excessive flavor-changing neutral currents can be avoided by a suitable alignment in flavor space. Read More

We calculate the fermionic corrections to the photon-energy spectrum of Bbar -> X_sgamma which arise from the self-interference of the chromomagnetic dipole operator Q_8 at next-to-next-to-leading order by applying naive non-abelianization. The resulting O(beta_0 alpha_s^2) correction to the Bbar -> X_sgamma branching ratio amounts to a relative shift of +0.12% (+0. Read More

We calculate the ttbar forward-backward asymmetry, A_FB^t, in Randall-Sundrum (RS) models taking into account the dominant next-to-leading order (NLO) corrections in QCD. At Born level we include the exchange of Kaluza-Klein (KK) gluons and photons, the Z boson and its KK excitations, as well as the Higgs boson, whereas beyond the leading order (LO) we consider the interference of tree-level KK-gluon exchange with one-loop QCD box diagrams and the corresponding bremsstrahlungs corrections. We find that the strong suppression of LO effects, that arises due to the elementary nature and the mostly vector-like couplings of light quarks, is lifted at NLO after paying the price of an additional factor of alpha_s/(4 pi). Read More

We present the Flavour Les Houches Accord (FLHA) which specifies a unique set of conventions for flavour-related parameters and observables. The FLHA uses the generic SUSY Les Houches Accord (SLHA) file structure. It defines the relevant Standard Model masses, Wilson coefficients, decay constants, bag parameters, flavour observables, etc. Read More

We reexamine the Randall-Sundrum (RS) model with enlarged gauge symmetry SU(2)_L x SU(2)_R x U(1)_X x P_LR in the presence of a brane-localized Higgs sector. In contrast to the existing literature, we perform the Kaluza-Klein (KK) decomposition within the mass basis, which avoids the truncation of the KK towers. Expanding the low-energy spectrum as well as the gauge couplings in powers of the Higgs vacuum expectation value, we obtain analytic formulas which allow for a deep understanding of the model-specific protection mechanisms of the T parameter and the left-handed Z-boson couplings. Read More

The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem - is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Read More

A comprehensive analysis of tree-level weak interaction processes at low energy is presented for the Randall-Sundrum (RS) model with SU(2)_L * U(1)_Y bulk gauge symmetry and brane-localized Higgs sector. The complete form of the effective weak Hamiltonian is obtained, which results from tree-level exchange of Kaluza-Klein (KK) gluons and photons, the W^+- and Z^0 bosons and their KK excitations, as well as the Higgs boson. Exact expressions are used for the bulk profiles of the various fields, and for the exchange of entire towers of KK gauge-boson states. Read More

2009Jul
Authors: M. Antonelli, D. M. Asner, D. Bauer, T. Becher, M. Beneke, A. J. Bevan, M. Blanke, C. Bloise, M. Bona, A. Bondar, C. Bozzi, J. Brod, A. J. Buras, N. Cabibbo, A. Carbone, G. Cavoto, V. Cirigliano, M. Ciuchini, J. P. Coleman, D. P. Cronin-Hennessy, J. P. Dalseno, C. H. Davies, F. DiLodovico, J. Dingfelder, Z. Dolezal, S. Donati, W. Dungel, U. Egede, G. Eigen, R. Faccini, T. Feldmann, F. Ferroni, J. M. Flynn, E. Franco, M. Fujikawa, I. K. Furic, P. Gambino, E. Gardi, T. J. Gershon, S. Giagu, E. Golowich, T. Goto, C. Greub, C. Grojean, D. Guadagnoli, U. A. Haisch, R. F. Harr, A. H. Hoang, T. Hurth, G. Isidori, D. E. Jaffe, A. Jüttner, S. Jäger, A. Khodjamirian, P. Koppenburg, R. V. Kowalewski, P. Krokovny, A. S. Kronfeld, J. Laiho, G. Lanfranchi, T. E. Latham, J. Libby, A. Limosani, D. Lopes Pegna, C. D. Lu, V. Lubicz, E. Lunghi, V. G. Lüth, K. Maltman, W. J. Marciano, E. C. Martin, G. Martinelli, F. Martinez-Vidal, A. Masiero, V. Mateu, F. Mescia, G. Mohanty, M. Moulson, M. Neubert, H. Neufeld, S. Nishida, N. Offen, M. Palutan, P. Paradisi, Z. Parsa, E. Passemar, M. Patel, B. D. Pecjak, A. A. Petrov, A. Pich, M. Pierini, B. Plaster, A. Powell, S. Prell, J. Rademaker, M. Rescigno, S. Ricciardi, P. Robbe, E. Rodrigues, M. Rotondo, R. Sacco, C. J. Schilling, O. Schneider, E. E. Scholz, B. A. Schumm, C. Schwanda, A. J. Schwartz, B. Sciascia, J. Serrano, J. Shigemitsu, I. J. Shipsey, A. Sibidanov, L. Silvestrini, F. Simonetto, S. Simula, C. Smith, A. Soni, L. Sonnenschein, V. Sordini, M. Sozzi, T. Spadaro, P. Spradlin, A. Stocchi, N. Tantalo, C. Tarantino, A. V. Telnov, D. Tonelli, I. S. Towner, K. Trabelsi, P. Urquijo, R. S. Van de Water, R. J. Van Kooten, J. Virto, G. Volpi, R. Wanke, S. Westhoff, G. Wilkinson, M. Wingate, Y. Xie, J. Zupan

One of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor and measurements and theoretical interpretations of their results have advanced tremendously: apart from masses and quantum numbers of flavor particles, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. Till early 1990s observations of CP violation were confined to neutral $K$ mesons, but since then a large number of CP-violating processes have been studied in detail in neutral $B$ mesons. Read More

2008Nov
Affiliations: 1Johannes Gutenberg University Mainz, 2Johannes Gutenberg University Mainz, 3Johannes Gutenberg University Mainz, 4Johannes Gutenberg University Mainz, 5Johannes Gutenberg University Mainz

A detailed phenomenological analysis of neutral kaon mixing in "little Randall-Sundrum" models is presented. It is shown that the constraints arising from the CP-violating quantity epsilon_K can, depending on the value of the ultra-violet cutoff, be even stronger than in the original Randall-Sundrum scenario addressing the hierarchy problem up to the Planck scale. The origin of the enhancement is explained, and a bound Lambda_{UV}>several 10^3 TeV is derived, below which vast corrections to epsilon_K are generically unavoidable. Read More