Archivi tag: New Physics

Rencontres de Blois on Particle Physics and Cosmology

Particle Physics and Cosmology will emphasize the increasing interplay between high energy accelerator based physics and cosmology. The conference will consist of plenary sessions for invited in depth oral presentations (review talks and talks on specific specialised topics), and contributed papers, in the form of relatively short talks. Continua a leggere Rencontres de Blois on Particle Physics and Cosmology

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Off-the-Beaten-Track Dark Matter and Astrophysical Probes of Fundamental Physics

The workshop will bring together experimental, observational and theoretical communities, in the fields of astro-particle physics, early universe cosmology and dark matter searches and phenomenology. Continua a leggere Off-the-Beaten-Track Dark Matter and Astrophysical Probes of Fundamental Physics

Looking for ‘new physics’ in the Universe

Con il termine “nuova fisica” si intende un nuovo campo di ricerca che tenta di spiegare quei fenomeni della natura che i fisici non sono ancora in grado di descrivere. Oggi, sta prendendo piede sempre più l’idea in base alla quale l’Universo può essere caratterizzato da una struttura diversa rispetto a quanto previsto dagli attuali modelli o teorie. In tal senso, un gruppo di fisici hanno avviato uno studio che avrà lo scopo di aiutare gli scienziati a rendere più facile, almeno in parte, la comprensione di alcuni fenomeni della fisica fondamentale.

New physics is about searching for unknown physical phenomena not known from the current perception of the Universe. Such phenomena are inherently very difficult to detect“, explains Matin Mojaza from CP3-Origins. Together with colleagues Stanley J. Brodsky from Stanford University in the U.S. and Xing-Gang Wu from Chongqing University in China, Mojaza has now succeeding in creating a new method that can make it easier to search for new physics in the Universe (post).

The method is a so called scalesetting procedure, and it fills out some empty, but very important, holes in the theories, models and simulations, which form the basis for all particle physics today.

With this method we can eliminate much of the uncertainty in theories and models of today“, says Matin Mojaza. Many theories and models in particle physics today has the problem that they, together with their predictions, provide some parameters that scientists do not know how to set. “Physicists do not know what values they should give these parameters. For example, when we study the Standard Model and see these unknown parameters, we cannot know whether they should be interpreted as conditions that support or oppose to the Standard Model, this makes it quite difficult to study the Standard Model accurately enough to investigate its value”, explains Matin Mojaza. With the new approach researchers can now completely clean their models for the unknown parameters and thus become better at assessing whether a theory or a model holds water.

The Standard Model has for the last 50 years been the prevailing theory of how the Universe is constructed. According to this theory, 16 (17 if we include the Higgs particle) subatomic particles form the basis for everything in the Universe.

But the Standard Model is starting to fall short, so it is now necessary to look for new physics in the Universe. One of the Standard Model’s major problems is that it cannot explain gravity, and another is that it cannot explain the existence of dark matter, believed to make up 25 percent of all matter in the Universe. In addition, the properties of the newly discovered Higgs particle, as described in the Standard Model, is incompatible with a stable Universe. “A part of the Standard Model is the theory of quantum chromodynamics, and this is one of the first things, we want to review with our new method, so that we can clean it from the uncertainties“, explains Matin Mojaza. The theory of quantum chromodynamics predicts how quarks (such as protons and neutrons) and gluons (particles that keeps quarks in place inside the protons and neutrons) interact. Matin and his Chinese and American colleagues now estimate that there may be a basis for reviewing many scientific calculations to clean the results from uncertainties and thus obtain a more reliable picture of whether the results support or contradict current models and theories. “Maybe we find new indications of new physics, which we would not have exposed if we had not had this new method”, says Matin Mojaza.

He believes that the Standard Model needs to be extended so that it can explain the Higgs particle, dark matter and gravity.

One possibility in this regard is to examine the so-called technicolor theory, and another is the theory of supersymmetry. According to the supersymmetry theory, each particle has a partner somewhere in the Universe (these have not yet been found though). According to the technicolor theory there is a special techni-force that binds so-called techni-quarks, which can form other particles, perhaps this is how the Higgs particle is formed. This could explain the problems with the current model of the Higgs particle. Also Rolf-Dieter Heuer, director of CERN in Switzerland, where the famous 27 km long particle accelerator, the LHC, is situated, believes that the search for new physics is important. According to him, the Standard Model cannot be the ultimate theory, and it is only capable of describing about 35 percent of the Universe. Like CP3-Origins, also CERN has put focus on weeding out old theories and search for new physics, this happening in 2015, when the accelerator starts up again (post).

University of Southern Denmark: New groundbreaking research may expose new aspects of the Universe

arXiv: A Systematic All-Orders Method to Eliminate Renormalization-Scale and Scheme Ambiguities in PQCD

Primi segnali di una ‘nuova’ fisica?

Finora, il modello standard rappresenta la miglior descrizione delle proprietà e del comportamento delle particelle elementari e delle interazioni fondamentali. Tuttavia, esso presenta dei punti deboli poiché non spiega alcuni fenomeni come, ad esempio, la materia scura o le interazioni gravitazionali tra le particelle. Oggi i fisici sono impegnati a cercare una teoria ancora più fondamentale, che essi chiamano “nuova fisica”, anche se non abbiamo ancora una prova diretta della sua esistenza.

Un gruppo di fisici guidati da Joaquim Matias dell’Università Autonoma di Barcellona affermano che questa teoria fondamentale implichi l’esistenza di alcune deviazioni nella distribuzione di probabilità associata al decadimento di una specifica particella, il mesone B.

Dunque, la determinazione per via sperimentale di queste piccole variazioni rappresenterebbe la prima prova diretta dell’esistenza di ‘nuovi’ processi fisici.

Lo scorso 19 Luglio, gli scienziati che lavorano all’esperimento LHCb presso il grande collisore adronico LHC del CERN di Ginevra hanno presentato i risultati degli esperimenti relativi al decadimento del mesone B durante la conferenza annuale EPS 2013 che si è tenuta quest’anno a Stoccolma, in Svezia. Le loro misure presentano una deviazione standard pari a 4,5 sigma rispetto alle previsioni del modello standard e permettono di identificare la loro origine da una unica sorgente. Se confermati, si tratta di un grande evento dato che gli scienziati parlano di ‘prova scientifica’ quando si ha una deviazione standard di 3 sigma e si parla, invece, di una ‘scoperta’ quando si raggiunge una deviazione standard di 5 sigma. “Dobbiamo essere prudenti”, spiega Matias, “ma se questi risultati saranno confermati potremo parlare della prima prova diretta dell’esistenza di una nuova fisica. Inoltre, se il bosone di Higgs completa il puzzle del modello standard, allora questi risultati potranno essere considerati il primo tassello di un puzzle ancora più grande”. Inoltre, i ricercatori dichiarano che uno dei modelli che potrebbe spiegare questi risultati dovrebbe essere quello che postula l’esistenza di una nuova particella denominata “Zprima”.

UAB: First experimental signs of a "New Physics" beyond the Standard Model

arXiv: Understanding the B->K*mu+mu- Anomaly


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